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2021-07-27
Spin transport-induced damping of coherent THz spin dynamics in iron
We study the damping of perpendicular standing spin-waves (PSSWs) in ultrathin Fe films at frequencies up to 2.4 THz. The PSSWs are excited by optically generated ultrashort spin current pulses, and probed optically in the time domain. Analyzing the wavenumber and thickness dependence of the damping, we demonstrate tha...
2107.12812v2
2021-09-03
Stabilization of the damped plate equation under general boundary conditions
We consider a damped plate equation on an open bounded subset of R^d, or a smooth manifold, with boundary, along with general boundary operators fulfilling the Lopatinskii-Sapiro condition. The damping term acts on a region without imposing a geometrical condition. We derive a resolvent estimate for the generator of th...
2109.01521v2
2021-09-07
Fluid energy cascade rate and kinetic damping: new insight from 3D Landau-fluid simulations
Using an exact law for incompressible Hall magnetohydrodynamics (HMHD) turbulence, the energy cascade rate is computed from three-dimensional HMHD-CGL (bi-adiabatic ions and isothermal electrons) and Landau fluid (LF) numerical simulations that feature different intensities of Landau damping over a broad range of waven...
2109.03123v2
2021-09-24
Effect of nonlocal transformations on the linearizability and exact solvability of the nonlinear generalized modified Emden type equations
The nonlinear generalized modified Emden type equations (GMEE) are known to be linearizable into simple harmonic oscillator (HO) or damped harmonic oscillators (DHO) via some nonlocal transformations. Hereby, we show that the structure of the nonlocal transformation and the linearizability into HO or DHO determine the ...
2109.12059v1
2022-01-12
Implicit Bias of MSE Gradient Optimization in Underparameterized Neural Networks
We study the dynamics of a neural network in function space when optimizing the mean squared error via gradient flow. We show that in the underparameterized regime the network learns eigenfunctions of an integral operator $T_{K^\infty}$ determined by the Neural Tangent Kernel (NTK) at rates corresponding to their eigen...
2201.04738v1
2022-01-19
Variance-Reduced Stochastic Quasi-Newton Methods for Decentralized Learning: Part II
In Part I of this work, we have proposed a general framework of decentralized stochastic quasi-Newton methods, which converge linearly to the optimal solution under the assumption that the local Hessian inverse approximations have bounded positive eigenvalues. In Part II, we specify two fully decentralized stochastic q...
2201.07733v1
2022-01-19
Active tuning of plasmon damping via light induced magnetism
Circularly polarized optical excitation of plasmonic nanostructures causes coherent circulating motion of their electrons, which in turn, gives rise to strong optically induced magnetization - a phenomenon known as the inverse Faraday effect (IFE). In this study we report how the IFE also significantly decreases plasmo...
2201.07842v1
2022-03-02
Simplified Stability Assessment of Power Systems with Variable-Delay Wide-Area Damping Control
Power electronic devices such as HVDC and FACTS can be used to improve the damping of poorly damped inter-area modes in large power systems. This involves the use of wide-area feedback signals, which are transmitted via communication networks. The performance of the closed-loop system is strongly influenced by the dela...
2203.01362v1
2022-03-03
Forward-modulated damping estimates and nonlocalized stability of periodic Lugiato-Lefever wave
In an interesting recent analysis, Haragus-Johnson-Perkins-de Rijk have shown modulational stability under localized perturbations of steady periodic solutions of the Lugiato-Lefever equation (LLE), in the process pointing out a difficulty in obtaining standard "nonlinear damping estimates" on modulated perturbation va...
2203.01770v3
2022-03-31
Observing Particle Energization above the Nyquist Frequency: An Application of the Field-Particle Correlation Technique
The field-particle correlation technique utilizes single-point measurements to uncover signatures of various particle energization mechanisms in turbulent space plasmas. The signature of Landau damping by electrons has been found in both simulations and observations from Earth's magnetosheath using this technique, but ...
2204.00104v1
2022-04-06
A Potential Based Quantization Procedure of the Damped Oscillator
Nowadays, two of the most prospering fields of physics are quantum computing and spintronics. In both, the loss of information and dissipation plays a crucial role. In the present work we formulate the quantization of the dissipative oscillator, which aids understanding of the above mentioned, and creates a theoretical...
2204.02893v2
2022-04-19
Role of shape anisotropy on thermal gradient-driven domain wall dynamics in magnetic nanowires
We investigate the magnetic domain wall (DW) dynamics in uniaxial/biaxial nanowires under a thermal gradient (TG). The findings reveal that the DW propagates toward the hotter region in both nanowires. The main physics of such observations is the magnonic angular momentum transfer to the DW. The hard (shape) anisotropy...
2204.09101v2
2022-04-25
Energy decay estimates for the wave equation with supercritical nonlinear damping
We consider a damped wave equation in a bounded domain. The damping is nonlinear and is homogeneous with degree p -- 1 with p > 2. First, we show that the energy of the strong solution in the supercritical case decays as a negative power of t; the rate of decay is the same as in the subcritical or critical cases, provi...
2204.11494v1
2022-05-07
Proposal for a Damping-Ring-Free Electron Injector for Future Linear Colliders
The current designs of future electron-positron linear colliders incorporate large and complex damping rings to produce asymmetric beams for beamstrahlung suppression. Here we present the design of an electron injector capable of delivering flat electron beams with phase-space partition comparable to the electron-beam ...
2205.03736v1
2022-06-02
Optimal Control of the 3D Damped Navier-Stokes-Voigt Equations with Control Constraints
In this paper, we consider the 3D Navier-Stokes-Voigt (NSV) equations with nonlinear damping $|u|^{r-1}u, r\in[1,\infty)$ in bounded and space-periodic domains. We formulate an optimal control problem of minimizing the curl of the velocity field in the energy norm subject to the flow velocity satisfying the damped NSV ...
2206.00988v2
2022-06-05
Stationary measures for stochastic differential equations with degenerate damping
A variety of physical phenomena involve the nonlinear transfer of energy from weakly damped modes subjected to external forcing to other modes which are more heavily damped. In this work we explore this in (finite-dimensional) stochastic differential equations in $\mathbb R^n$ with a quadratic, conservative nonlinearit...
2206.02240v1
2022-06-17
Resolvent estimates for the one-dimensional damped wave equation with unbounded damping
We study the generator $G$ of the one-dimensional damped wave equation with unbounded damping. We show that the norm of the corresponding resolvent operator, $\| (G - \lambda)^{-1} \|$, is approximately constant as $|\lambda| \to +\infty$ on vertical strips of bounded width contained in the closure of the left-hand sid...
2206.08820v2
2022-08-04
Lp-asymptotic stability of 1D damped wave equations with localized and nonlinear damping
In this paper, we study the $L^p$-asymptotic stability with $p\in (1,\infty)$ of the one-dimensional nonlinear damped wave equation with a localized damping and Dirichlet boundary conditions in a bounded domain $(0,1)$. We start by addressing the well-posedness problem. We prove the existence and the uniqueness of weak...
2208.02779v1
2022-08-07
Damping of neutrino oscillations, decoherence and the lengths of neutrino wave packets
Spatial separation of the wave packets (WPs) of neutrino mass eigenstates leads to decoherence and damping of neutrino oscillations. Damping can also be caused by finite energy resolution of neutrino detectors or, in the case of experiments with radioactive neutrino sources, by finite width of the emitted neutrino line...
2208.03736v2
2022-08-23
Fate of exceptional points in the presence of nonlinearities
The non-Hermitian dynamics of open systems deal with how intricate coherent effects of a closed system intertwine with the impact of coupling to an environment. The system-environment dynamics can then lead to so-called exceptional points, which are the open-system marker of phase transitions, i.e., the closing of spec...
2208.11205v2
2022-09-10
Data-driven, multi-moment fluid modeling of Landau damping
Deriving governing equations of complex physical systems based on first principles can be quite challenging when there are certain unknown terms and hidden physical mechanisms in the systems. In this work, we apply a deep learning architecture to learn fluid partial differential equations (PDEs) of a plasma system base...
2209.04726v1
2022-09-25
Formation of the cosmic-ray halo: The role of nonlinear Landau damping
We present a nonlinear model of self-consistent Galactic halo, where the processes of cosmic ray (CR) propagation and excitation/damping of MHD waves are included. The MHD-turbulence, which prevents CR escape from the Galaxy, is entirely generated by the resonant streaming instability. The key mechanism controlling the...
2209.12302v1
2022-10-14
Landau damping for gravitational waves in parity-violating theories
We discuss how tensor polarizations of gravitational waves can suffer Landau damping in the presence of velocity birefringence, when parity symmetry is explicitly broken. In particular, we analyze the role of the Nieh-Yan and Chern-Simons terms in modified theories of gravity, showing how the gravitational perturbation...
2210.07673v2
2022-10-25
Formation of shifted shock for the 3D compressible Euler equations with damping
In this paper, we show the shock formation of the solutions to the 3-dimensional (3D) compressible isentropic and irrotational Euler equations with damping for the initial short pulse data which was first introduced by D.Christodoulou\cite{christodoulou2007}. Due to the damping effect, the largeness of the initial data...
2210.13796v1
2022-10-30
Dynamics of a class of extensible beams with degenerate and non-degenerate nonlocal damping
This work is concerned with new results on long-time dynamics of a class of hyperbolic evolution equations related to extensible beams with three distinguished nonlocal nonlinear damping terms. In the first possibly degenerate case, the results feature the existence of a family of compact global attractors and a thickn...
2210.16851v1
2022-11-11
Nonlinear fractional damped wave equation on compact Lie groups
In this paper, we deal with the initial value fractional damped wave equation on $G$, a compact Lie group, with power-type nonlinearity. The aim of this manuscript is twofold. First, using the Fourier analysis on compact Lie groups, we prove a local in-time existence result in the energy space for the fractional damped...
2211.06155v1
2022-11-16
Controlling the motional quality factor of a diamagnetically levitated graphite plate
Researchers seek methods to levitate matter for a wide variety of purposes, ranging from exploring fundamental problems in science, through to developing new sensors and mechanical actuators. Many levitation techniques require active driving and most can only be applied to objects smaller than a few micrometers. Diamag...
2211.08764v1
2022-12-03
Strong On-Chip Microwave Photon-Magnon Coupling Using Ultra-low Damping Epitaxial Y3Fe5O12 Films at 2 Kelvin
Y3Fe5O12 is arguably the best magnetic material for magnonic quantum information science (QIS) because of its extremely low damping. We report ultralow damping at 2 K in epitaxial Y3Fe5O12 thin films grown on a diamagnetic Y3Sc2Ga3O12 substrate that contains no rare-earth elements. Using these ultralow damping YIG film...
2212.01708v1
2022-12-21
Fractional damping effects on the transient dynamics of the Duffing oscillator
We consider the nonlinear Duffing oscillator in presence of fractional damping which is characteristic in different physical situations. The system is studied with a smaller and larger damping parameter value, that we call the underdamped and overdamped regimes. In both we have studied the relation between the fraction...
2212.11023v1
2023-01-19
Damped harmonic oscillator revisited: the fastest route to equilibrium
Theoretically, solutions of the damped harmonic oscillator asymptotically approach equilibrium, i.e., the zero energy state, without ever reaching it exactly, and the critically damped solution approaches equilibrium faster than the underdamped or the overdamped solution. Experimentally, the systems described with this...
2301.08222v2
2023-01-22
Boundary stabilization of a vibrating string with variable length
We study small vibrations of a string with time-dependent length $\ell(t)$ and boundary damping. The vibrations are described by a 1-d wave equation in an interval with one moving endpoint at a speed $\ell'(t)$ slower than the speed of propagation of the wave c=1. With no damping, the energy of the solution decays if t...
2301.09086v1
2023-02-24
Asymptotic behaviour of the semidiscrete FE approximations to weakly damped wave equations with minimal smoothness on initial data
Exponential decay estimates of a general linear weakly damped wave equation are studied with decay rate lying in a range. Based on the $C^0$-conforming finite element method to discretize spatial variables keeping temporal variable continuous, a semidiscrete system is analysed, and uniform decay estimates are derived w...
2302.12476v1
2023-02-27
Nonlinear acoustic imaging with damping
In this paper, we consider an inverse problem for a nonlinear wave equation with a damping term and a general nonlinear term. This problem arises in nonlinear acoustic imaging and has applications in medical imaging and other fields. The propagation of ultrasound waves can be modeled by a quasilinear wave equation with...
2302.14174v1
2023-04-11
Sizable suppression of magnon Hall effect by magnon damping in Cr$_2$Ge$_2$Te$_6$
Two-dimensional (2D) Heisenberg honeycomb ferromagnets are expected to have interesting topological magnon effects as their magnon dispersion can have Dirac points. The Dirac points are gapped with finite second nearest neighbor Dzyaloshinskii-Moriya interaction, providing nontrivial Berry curvature with finite magnon ...
2304.04922v1
2023-05-22
Semi-active damping optimization of vibrational systems using the reduced basis method
In this article, we consider vibrational systems with semi-active damping that are described by a second-order model. In order to minimize the influence of external inputs to the system response, we are optimizing some damping values. As minimization criterion, we evaluate the energy response, that is the $\cH_2$-norm ...
2305.12946v1
2023-06-01
A combined volume penalization / selective frequency damping approach for immersed boundary methods: application to moving geometries
This work extends, to moving geometries, the immersed boundary method based on volume penalization and selective frequency damping approach [J. Kou, E. Ferrer, A combined volume penalization/selective frequency damping approach for immersed boundary methods applied to high-order schemes, Journal of Computational Physic...
2306.00504v1
2023-06-09
Damped nonlinear Schrödinger equation with Stark effect
We study the $L^2$-critical damped NLS with a Stark potential. We prove that the threshold for global existence and finite time blowup of this equation is given by $\|Q\|_2$, where $Q$ is the unique positive radial solution of $\Delta Q + |Q|^{4/d} Q = Q$ in $H^1(\mathbb{R}^d)$. Moreover, in any small neighborhood of $...
2306.05931v1
2023-06-19
New Perspectives and Systematic Approaches for Analyzing Negative Damping-Induced Sustained Oscillation
Sustained oscillations (SOs) are commonly observed in systems dominated by converters. Under specific conditions, even though the origin of SOs can be identified through negative damping modes using conventional linear analysis, utilizing the describing function to compute harmonic amplitude and frequency remains incom...
2306.10839v2
2023-06-24
Numerical approximation of the invariant distribution for a class of stochastic damped wave equations
We study a class of stochastic semilinear damped wave equations driven by additive Wiener noise. Owing to the damping term, under appropriate conditions on the nonlinearity, the solution admits a unique invariant distribution. We apply semi-discrete and fully-discrete methods in order to approximate this invariant dist...
2306.13998v1
2023-07-31
Estimation of Power in the Controlled Quantum Teleportation through the Witness Operator
Controlled quantum teleportation (CQT) can be considered as a variant of quantum teleportation in which three parties are involved where one party acts as the controller. The usability of the CQT scheme depends on two types of fidelities viz. conditioned fidelity and non-conditioned fidelity. The difference between the...
2307.16574v1
2023-08-03
Triple-Spherical Bessel Function Integrals with Exponential and Gaussian Damping: Towards an Analytic N-Point Correlation Function Covariance Model
Spherical Bessel functions appear commonly in many areas of physics wherein there is both translation and rotation invariance, and often integrals over products of several arise. Thus, analytic evaluation of such integrals with different weighting functions (which appear as toy models of a given physical observable, su...
2308.01955v2
2023-08-28
Quantized damped transversal single particle mechanical waves
In information transfer, the dissipation of a signal may have crucial importance. The feasibility of reconstructing the distorted signal also depends on this. That is why the study of quantized dissipative transversal single particle mechanical waves may have an important role. It may be true, particularly on the nanos...
2308.14820v1
2023-11-15
Integrated Local Energy Decay for Damped Magnetic Wave Equations on Stationary Space-Times
We establish local energy decay for damped magnetic wave equations on stationary, asymptotically flat space-times subject to the geometric control condition. More specifically, we allow for the addition of time-independent magnetic and scalar potentials, which negatively affect energy coercivity and may add in unwieldy...
2311.08628v1
2023-11-15
Applications of $L^p-L^q$ estimates for solutions to semi-linear $σ$-evolution equations with general double damping
In this paper, we would like to study the linear Cauchy problems for semi-linear $\sigma$-evolution models with mixing a parabolic like damping term corresponding to $\sigma_1 \in [0,\sigma/2)$ and a $\sigma$-evolution like damping corresponding to $\sigma_2 \in (\sigma/2,\sigma]$. The main goals are on the one hand to...
2311.09085v1
2023-12-07
Generalized Damping Torque Analysis of Ultra-Low Frequency Oscillation in the Jerk Space
Ultra low frequency oscillation (ULFO) is significantly threatening the power system stability. Its unstable mechanism is mostly studied via generalized damping torque analysis method (GDTA). However, the analysis still adopts the framework established for low frequency oscillation. Hence, this letter proposes a GDTA a...
2312.04148v1
2023-12-08
Selective damping of plasmons in coupled two-dimensional systems by Coulomb drag
The Coulomb drag is a many-body effect observed in proximized low-dimensional systems. It appears as emergence of voltage in one of them upon passage of bias current in another. The magnitude of drag voltage can be strongly affected by exchange of plasmonic excitations between the layers; however, the reverse effect of...
2312.05097v1
2023-12-13
Geometrical Interpretation of Neutrino Oscillation with decay
The geometrical representation of two-flavor neutrino oscillation represents the neutrino's flavor eigenstate as a magnetic moment-like vector that evolves around a magnetic field-like vector that depicts the Hamiltonian of the system. In the present work, we demonstrate the geometrical interpretation of neutrino in a ...
2312.08178v1
2024-01-01
Magnon Damping Minimum and Logarithmic Scaling in a Kondo-Heisenberg Model
Recently, an anomalous temperature evolution of spin wave excitations has been observed in a van der Waals metallic ferromagnet Fe$_3$GeTe$_2$ (FGT) [S. Bao, et al., Phys. Rev. X 12, 011022 (2022)], whose theoretical understanding yet remains elusive. Here we study the spin dynamics of a ferromagnetic Kondo-Heisenberg ...
2401.00758v1
2024-01-04
Simplified Information Geometry Approach for Massive MIMO-OFDM Channel Estimation -- Part II: Convergence Analysis
In Part II of this two-part paper, we prove the convergence of the simplified information geometry approach (SIGA) proposed in Part I. For a general Bayesian inference problem, we first show that the iteration of the common second-order natural parameter (SONP) is separated from that of the common first-order natural p...
2401.02037v1
2024-01-05
Solving convex optimization problems via a second order dynamical system with implicit Hessian damping and Tikhonov regularization
This paper deals with a second order dynamical system with a Tikhonov regularization term in connection to the minimization problem of a convex Fr\'echet differentiable function. The fact that beside the asymptotically vanishing damping we also consider an implicit Hessian driven damping in the dynamical system under s...
2401.02676v1
2024-01-16
Influence of temperature, doping, and amorphization on the electronic structure and magnetic damping of iron
Hybrid magnonic quantum systems have drawn increased attention in recent years for coherent quantum information processing, but too large magnetic damping is a persistent concern when metallic magnets are used. Their intrinsic damping is largely determined by electron-magnon scattering induced by spin-orbit interaction...
2401.08076v1
2024-03-13
Effects of wave damping and finite perpendicular scale on three-dimensional Alfvén wave parametric decay in low-beta plasmas
Shear Alfven wave parametric decay instability (PDI) provides a potential path toward significant wave dissipation and plasma heating. However, fundamental questions regarding how PDI is excited in a realistic three-dimensional (3D) open system and how critically the finite perpendicular wave scale -- as found in both ...
2403.08179v1
2024-03-19
Polarization Dynamics in Paramagnet of Charged Quark-Gluon Plasma
It is commonly understood that the strong magnetic field produced in heavy ion collisions is short-lived. The electric conductivity of the quark-gluon plasma is unable to significantly extend the life time of magnetic field. We propose an alternative scenario to achieve this: with finite baryon density and spin polariz...
2403.12615v1
2006-04-14
The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System
As large optical quasar surveys for damped Lya become a reality and the study of star forming gas in the early Universe achieves statistical robustness, it is now vital to identify and quantify the sources of systematic error. Because the nature of optically-selected quasar surveys makes them vulnerable to dust obscura...
0604334v1
2012-04-12
Evidence of Gunn-Peterson damping wings in high-z quasar spectra: strengthening the case for incomplete reionization
The spectra of several high-redshift (z>6) quasars have shown evidence for a Gunn-Peterson (GP) damping wing, indicating a substantial mean neutral hydrogen fraction (x_HI > 0.03) in the z ~ 6 intergalactic medium (IGM). However, previous analyses assumed that the IGM was uniformly ionized outside of the quasar's HII r...
1204.2838v2
2013-05-31
Highly inclined and eccentric massive planets I: Planet-disc interactions
In the Solar System, planets have a small inclination with respect to the equatorial plane of the Sun, but there is evidence that in extrasolar systems the inclination can be very high. This spin-orbit misalignment is unexpected, as planets form in a protoplanetary disc supposedly aligned with the stellar spin. Planet-...
1305.7330v1
2014-10-20
Frequency-dependent attenuation and elasticity in unconsolidated earth materials: effect of damping
We use the Discrete Element Method (DEM) to understand the underlying attenuation mechanism in granular media, with special applicability to the measurements of the so-called effective mass developed earlier. We consider that the particles interact via Hertz-Mindlin elastic contact forces and that the damping is descri...
1410.5484v2
2020-08-05
Fast optimization via inertial dynamics with closed-loop damping
In a Hilbert space $H$, in order to develop fast optimization methods, we analyze the asymptotic behavior, as time $t$ tends to infinity, of inertial continuous dynamics where the damping acts as a closed-loop control. The function $f: H \to R$ to be minimized (not necessarily convex) enters the dynamic through it grad...
2008.02261v3
2023-01-10
Cosmic Ray Drag and Damping of Compressive Turbulence
While it is well-known that cosmic rays (CRs) can gain energy from turbulence via second order Fermi acceleration, how this energy transfer affects the turbulent cascade remains largely unexplored. Here, we show that damping and steepening of the compressive turbulent power spectrum are expected once the damping time $...
2301.04156v2
2024-02-12
Relaxation of weakly collisional plasma: continuous spectra, Landau eigenmodes, and transition from the collisionless to the fluid limit
The relaxation of a weakly collisional plasma is described by the Boltzmann-Poisson equations with the Lenard-Bernstein collision operator. We perform a perturbative analysis of these equations, and obtain, for the first time, exact analytic solutions, enabling definitive resolutions to long-standing controversies rega...
2402.07992v1
2008-06-23
On multi F-nomial coefficients and Inversion formula for F-nomial coefficients
In response to [6], we discover the looked for inversion formula for F-nomial coefficients. Before supplying its proof, we generalize F-nomial coefficients to multi F-nomial coefficients and we give their combinatorial interpretation in cobweb posets language, as the number of maximal-disjoint blocks of the form sP_{k_...
0806.3626v2
2015-07-06
On the Kendall Correlation Coefficient
In the present paper, we first discuss the Kendall rank correlation coefficient. In continuous case, we define the Kendall rank correlation coefficient in terms of the concomitants of order statistics, find the expected value of the Kendall rank correlation coefficient and show that the later is free of n. We also prov...
1507.01427v1
2017-10-12
The co-Pieri rule for Kronecker coefficients
A fundamental problem in the representation theory of the symmetric group, Sn, is to describe the coefficients in the decomposition of a tensor product of two simple representations. These coefficients are known in the literature as the Kronecker coefficients. The Littlewood--Richardson coefficients appear as an import...
1710.04523v3
2023-05-04
All Kronecker coefficients are reduced Kronecker coefficients
We settle the question of where exactly the reduced Kronecker coefficients lie on the spectrum between the Littlewood-Richardson and Kronecker coefficients by showing that every Kronecker coefficient of the symmetric group is equal to a reduced Kronecker coefficient by an explicit construction. This implies the equival...
2305.03003v1
1995-09-21
Damped Lyman-alpha and Lyman Limit Absorbers in the Cold Dark Matter Model
We study the formation of damped \lya and Lyman limit absorbers in a hierarchical clustering scenario using a gas dynamical simulation of an $\Omega = 1$, cold dark matter universe. In the simulation, these high column density systems are associated with forming galaxies. Damped \lya absorption, $N_{HI} \simgt 10^{20.2...
9509106v1
1995-09-21
Nonlinear Damping of Oscillations in Tidal-Capture Binaries
We calculate the damping of quadrupole f and low order g modes (primary modes) by nonlinear coupling to other modes of the star. This damping is orders of magnitude more rapid than direct radiative damping when the primary amplitude is large, as in tidal capture. Primary modes destabilize high degree g-modes of half ...
9509112v1
1997-08-12
Spectroscopy of PKS 0528-260: New Limits on CO Absorption and Emission
We have obtained a moderate resolution spectrum of the quasar PKS 0528-250 with the Red Channel Spectrograph on the Multiple Mirror Telescope (MMT) in order to study a damped Lyman alpha absorption line system at z = 2.8115. We obtain a new upper limit for the CO column density for the z = 2.8108 velocity component i...
9708104v1
1998-11-04
GMRT Observations of Low z Damped Lyman-alpha Absorbers
We present Giant Metrewave Radio Telescope (GMRT) observations of redshifted HI 21cm absorption in two low redshift (z=0.2212, z=0.0912) damped Lyman-alpha systems seen towards the gigahertz peaked source OI 363 (z_em = 0.630). The object at z=0.0912 is the lowest redshift damped Lyman-alpha system known to date. Groun...
9811068v1
2002-01-25
Galaxies Associated with z~4 Damped Lya Systems: I. Imaging and Photometric Selection
This paper describes the acquisition and analysis of imaging data for the identification of galaxies associated with z~4 damped Lya systems. We present deep BRI images of three fields known to contain four z~4 damped systems. We discuss the reduction and calibration of the data, detail the color criteria used to identi...
0201417v2
2002-02-25
Eccentricity Evolution for Planets in Gaseous Disks
We investigate the hypothesis that interactions between a giant planet and the disk from which it forms promote eccentricity growth. These interactions are concentrated at discrete Lindblad and corotation resonances. Interactions at principal Lindblad resonances cause the planet's orbit to migrate and open a gap in the...
0202462v1
2003-07-23
Dusty Molecular Cloud Collapse in the Presence of Alfvén Waves
It has been shown that magnetic fields play an important role in the stability of molecular clouds, mainly perpendicularly to the field direction. However, in the parallel direction the stability is a serious problem still to be explained. Interstellar turbulence may allow the generation of Alfv\'en waves that propagat...
0307411v1
2005-02-28
Thermal Evolution of a Pulsating Neutron Star
We have derived a set of equations to describe the thermal evolution of a neutron star which undergoes small-amplitude radial pulsations. We have taken into account, in the frame of the General Theory of Relativity, the pulsation damping due to the bulk and shear viscosity and the accompanying heating of the star. The ...
0502583v2
2005-05-02
Collisionless Damping of Fast MHD Waves in Magneto-rotational Winds
We propose collisionless damping of fast MHD waves as an important mechanism for the heating and acceleration of winds from rotating stars. Stellar rotation causes magnetic field lines anchored at the surface to form a spiral pattern and magneto-rotational winds can be driven. If the structure is a magnetically dominat...
0505013v5
2006-08-05
The nature of damped Lyman alpha and sub-damped Lyman alpha absorbers
We present arguments based on the measured abundances in individual damped Lyman alpha systems (DLAs) and sub-damped Lyman alpha systems (sub-DLAs), and also the average abundances inferred in large samples of QSO absorption line systems, to suggest that the amount of dust in intervening QSO absorbers is small and is n...
0608127v2
2007-02-12
The Ucsd/Keck Damped Lya Abundance Database: A Decade of High Resolution Spectroscopy
We publish the Keck/HIRES and Keck/ESI spectra that we have obtained during the first 10 years of Keck observatory operations. Our full sample includes 42 HIRES spectra and 39 ESI spectra along 65 unique sightlines providing abundance measurements on ~85 damped Lya systems. The normalized data can be downloaded from th...
0702325v1
1998-06-30
Structure and Spin Dynamics of La$_{0.85}$Sr$_{0.15}$MnO$_3$
Neutron scattering has been used to study the structure and spin dynamics of La$_{0.85}$Sr$_{0.15}$MnO$_3$. The magnetic structure of this system is ferromagnetic below T_C = 235 K. We see anomalies in the Bragg peak intensities and new superlattice peaks consistent with the onset of a spin-canted phase below T_{CA} = ...
9806381v1
2002-08-29
Some notes on ideology of waves in plasmas
Our last three papers provide an occasion to make some brief notes on ideology of waves in plasmas and to rehabilitate Vlasov prescription to calculate relevant logarithmically divergent integrals in the principal value sense. In this approach asymptotical solutions of plasma oscillations are selected according to self...
0208098v7
2007-04-12
The effect of the solar corona on the attenuation of small-amplitude prominence oscillations. I. Longitudinal magnetic field
Context. One of the typical features shown by observations of solar prominence oscillations is that they are damped in time and that the values of the damping times are usually between one and three times the corresponding oscillatory period. However, the mechanism responsible for the attenuation is still not well-know...
0704.1566v2
2007-10-01
Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization
One well-known way to constrain the hydrogen neutral fraction, x_H, of the high-redshift intergalactic medium (IGM) is through the shape of the red damping wing of the Lya absorption line. We examine this method's effectiveness in light of recent models showing that the IGM neutral fraction is highly inhomogeneous on l...
0710.0371v1
2008-02-11
Eccentricity of masing disks in Active Galactic Nuclei
Observations of Keplerian disks of masers in NCG 4258 and other Seyfert galaxies can be used to obtain geometric distance estimates and derive the Hubble constant. The ultimate precision of such measurements could be limited by uncertainties in the disk geometry. Using a time-dependent linear theory model, we study the...
0802.1524v1
2008-02-20
The Effect of Charon's Tidal Damping on the Orbits of Pluto's Three Moons
Pluto's recently discovered minor moons, Nix and Hydra, have almost circular orbits, and are nearly coplanar with Charon, Pluto's major moon. This is surprising because tidal interactions with Pluto are too weak to damp their eccentricities. We consider an alternative possibility: that Nix and Hydra circularize their o...
0802.2939v1
2008-03-18
Non-adiabatic magnetohydrodynamic waves in a cylindrical prominence thread with mass flow
High-resolution observations show that oscillations and waves in prominence threads are common and that they are attenuated in a few periods. In addition, observers have also reported the presence of material flows in such prominence fine-structures. Here we investigate the time damping of non-leaky oscillations suppor...
0803.2600v2
2008-07-28
Thermal fluctuations in moderately damped Josephson junctions: Multiple escape and retrapping, switching- and return-current distributions and hysteresis
A crossover at a temperature T* in the temperature dependence of the width s of the distribution of switching currents of moderately damped Josephson junctions has been reported in a number of recent publications, with positive ds/dT and IV characteristics associated with underdamped behaviour for lower temperatures T<...
0807.4502v1
2009-02-26
Viscous propagation of mass flow variability in accretion discs
We study mass flow rate through a disc resulting from a varying mass supply rate. Variable mass supply rate occurs, e.g., during disc state transitions, and in interacting eccentric binaries. It is, however, damped by the viscosity of the disc. Here, we calculate this damping in detail. We derive an analytical descript...
0902.4530v2
2010-04-09
Oscillations of weakly viscous conducting liquid drops in a strong magnetic field
We analyse small-amplitude oscillations of a weakly viscous electrically conducting liquid drop in a strong uniform DC magnetic field. An asymptotic solution is obtained showing that the magnetic field does not affect the shape eigenmodes, which remain the spherical harmonics as in the non-magnetic case. Strong magneti...
1004.1548v2
2011-02-03
Damping of Electron Density Structures and Implications for Interstellar Scintillation
The forms of electron density structures in kinetic Alfven wave turbulence are studied in connection with scintillation. The focus is on small scales $L \sim 10^8-10^{10}$ cm where the Kinetic Alfv\'en wave (KAW) regime is active in the interstellar medium. MHD turbulence converts to a KAW cascade, starting at 10 times...
1102.0810v2
2011-09-28
Different dimensionality trends in the Landau damping of magnons in iron, cobalt and nickel: time dependent density functional study
We study the Landau damping of ferromagnetic magnons in Fe, Co, and Ni as the dimensionality of the system is reduced from three to two. We resort to the \textit{ab initio} linear response time dependent density functional theory in the adiabatic local spin density approximation. The numerical scheme is based on the Ko...
1109.6217v2
2011-10-06
Dissipative and conservative nonlinearity in carbon nanotube and graphene mechanical resonators
Graphene and carbon nanotubes represent the ultimate size limit of one and two-dimensional nanoelectromechanical resonators. Because of their reduced dimensionality, graphene and carbon nanotubes display unusual mechanical behavior; in particular, their dynamics is highly nonlinear. Here, we review several types of non...
1110.1234v1
2012-06-02
Slow Mode Oscillations and Damping of Hot Solar Coronal Loops
The effect of temperature inhomogeneity on the periods, their ratios (fundamental vs. first overtone), and the damping times of the standing slow modes in gravitationally stratified solar coronal loops are studied. The effects of optically thin radiation, compressive viscosity, and thermal conduction are considered. Th...
1206.0366v1
2012-09-15
Damped kink oscillations of flowing prominence threads
Transverse oscillations of thin threads in solar prominences are frequently reported in high-resolution observations. Two typical features of the observations are that the oscillations are damped in time and that simultaneous mass flows along the threads are detected. Flows cause the dense threads to move along the pro...
1209.3382v1
2013-04-13
Parametric survey of longitudinal prominence oscillation simulations
It is found that both microflare-sized impulsive heating at one leg of the loop and a suddenly imposed velocity perturbation can propel the prominence to oscillate along the magnetic dip. An extensive parameter survey results in a scaling law, showing that the period of the oscillation, which weakly depends on the leng...
1304.3798v1
2013-06-08
Observation of a Berry phase anti-damping spin-orbit torque
Recent observations of current-induced magnetization switching at ferromagnet/normal-conductor interfaces have important consequences for future magnetic memory technology. In one interpretation, the switching originates from carriers with spin-dependent scattering giving rise to a relativistic anti-damping spin-orbit ...
1306.1893v1
2013-08-20
Stringent constraints on the H I spin temperature in two z > 3 Damped Lyman-alpha systems from redshifted 21 cm absorption studies
Physical properties of Damped Lyman-alpha absorbers and their evolution are closely related to galaxy formation and evolution theories, and have important cosmological implications. H I 21 cm absorption study is one useful way of measuring the temperature of these systems. In this work, very strong constraints on the t...
1308.4410v1
2013-09-26
Non-Landau damping of magnetic excitations in systems with localized and itinerant electrons
We discuss the form of the damping of magnetic excitations in a metal near a ferromagnetic instability. The paramagnon theory predicts that the damping term should have the form $\Omega/\Gamma (q)$ with $\Gamma (q) \propto q$ (the Landau damping). However, the experiments on uranium metallic compounds UGe$_2$ and UCoGe...
1309.7065v3
2014-06-16
Design of the Readout Electronics for the Qualification Model of DAMPE BGO Calorimeter
The DAMPE (DArk Matter Particle Explorer) is a scientific satellite being developed in China, aimed at cosmic ray study, gamma ray astronomy, and searching for the clue of dark matter particles, with a planned mission period of more than 3 years and an orbit altitude of about 500 km. The BGO Calorimeter, which consists...
1406.3886v1
2015-04-17
Chiral damping of magnetic domain walls
Structural symmetry breaking in magnetic materials is responsible for a variety of outstanding physical phenomena. Examples range from the existence of multiferroics, to current induced spin orbit torques (SOT) and the formation of topological magnetic structures. In this letter we bring into light a novel effect of th...
1504.04411v1
2015-07-28
Spatial damping of propagating sausage waves in coronal cylinders
Sausage modes are important in coronal seismology. Spatially damped propagating sausage waves were recently observed in the solar atmosphere. We examine how wave leakage influences the spatial damping of sausage waves propagating along coronal structures modeled by a cylindrical density enhancement embedded in a unifor...
1507.07724v1
2015-10-19
On the branching of the quasinormal resonances of near-extremal Kerr black holes
It has recently been shown by Yang. et. al. [Phys. Rev. D {\bf 87}, 041502(R) (2013)] that rotating Kerr black holes are characterized by two distinct sets of quasinormal resonances. These two families of quasinormal resonances display qualitatively different asymptotic behaviors in the extremal ($a/M\to 1$) black-hole...
1510.05604v1
2016-02-16
Damping and power spectra of quasi-periodic intensity disturbances above a solar polar coronal hole
We study intensity disturbances above a solar polar coronal hole seen in the AIA 171 \AA\ and 193 \AA\ passbands, aiming to provide more insights into their physical nature. The damping and power spectra of the intensity disturbances with frequencies from 0.07 mHz to 10.5 mHz are investigated. The damping of the intens...
1602.04883v1
2016-04-20
Nonlinear wave damping due to multi-plasmon resonances
For short wavelengths, it is well known that the linearized Wigner-Moyal equation predicts wave damping due to wave-particle interaction, where the resonant velocity shifted from the phase velocity by a velocity $v_q = \hbar k/2m$. Here $\hbar$ is the reduced Planck constant, $k$ is the wavenumber and $m$ is the electr...
1604.05983v2