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2018-11-07
Statistical complexity of the quasiperiodical damped systems
We consider the concept of statistical complexity to write the quasiperiodical damped systems applying the snapshot attractors. This allows us to understand the behaviour of these dynamical systems by the probability distribution of the time series making a difference between the regular, random and structural complexi...
1811.02958v1
2018-12-13
Rapid exponential stabilization of a 1-D transmission wave equation with in-domain anti-damping
We consider the problem of pointwise stabilization of a one-dimensional wave equation with an internal spatially varying anti-damping term. We design a feedback law based on the backstepping method and prove exponential stability of the closed-loop system with a desired decay rate.
1812.11035v1
2019-01-20
Stationary Solutions of Damped Stochastic 2-dimensional Euler's Equation
Existence of stationary point vortices solution to the damped and stochastically driven Euler's equation on the two dimensional torus is proved, by taking limits of solutions with finitely many vortices. A central limit scaling is used to show in a similar manner the existence of stationary solutions with white noise m...
1901.06744v1
2019-03-13
Solar $p$-mode damping rates: insight from a 3D hydrodynamical simulation
Space-borne missions CoRoT and Kepler have provided a rich harvest of high-quality photometric data for solar-like pulsators. It is now possible to measure damping rates for hundreds of main-sequence and thousands of red-giant. However, among the seismic parameters, mode damping rates remain poorly understood and thus ...
1903.05479v1
2019-04-15
Carleman estimate for an adjoint of a damped beam equation and an application to null controllability
In this article we consider a control problem of a linear Euler-Bernoulli damped beam equation with potential in dimension one with periodic boundary conditions. We derive a new Carleman estimate for an adjoint of the equation under consideration. Then using a well known duality argument we obtain explicitly the contro...
1904.07038v1
2019-05-01
Dissipative structure and diffusion phenomena for doubly dissipative elastic waves in two space dimensions
In this paper we study the Cauchy problem for doubly dissipative elastic waves in two space dimensions, where the damping terms consist of two different friction or structural damping. We derive energy estimates and diffusion phenomena with different assumptions on initial data. Particularly, we find the dominant influ...
1905.00257v1
2019-07-12
Non-Existence of Periodic Orbits for Forced-Damped Potential Systems in Bounded Domains
We prove Lr-estimates on periodic solutions of periodically-forced, linearly-damped mechanical systems with polynomially-bounded potentials. The estimates are applied to obtain a non-existence result of periodic solutions in bounded domains, depending on an upper bound on the gradient of the potential. The results are ...
1907.05778v1
2019-09-02
On the inclusion of damping terms in the hyperbolic MBO algorithm
The hyperbolic MBO is a threshold dynamic algorithm which approximates interfacial motion by hyperbolic mean curvature flow. We introduce a generalization of this algorithm for imparting damping terms onto the equation of motion. We also construct corresponding numerical methods, and perform numerical tests. We also us...
1909.00552v1
2019-09-07
Lindblad dynamics of the damped and forced quantum harmonic oscillator: General solution
The quantum dynamics of a damped and forced harmonic oscillator described by a Lindblad master equation is analyzed. The master equation is converted into a matrix-vector representation and the resulting non-Hermitian Schr\"odinger equation is solved by Lie-algebraic techniques allowing the construction of the general ...
1909.03206v1
2019-11-01
Convergence of a damped Newton's method for discrete Monge-Ampere functions with a prescribed asymptotic cone
We prove the convergence of a damped Newton's method for the nonlinear system resulting from a discretization of the second boundary value problem for the Monge-Ampere equation. The boundary condition is enforced through the use of the notion of asymptotic cone. The differential operator is discretized based on a parti...
1911.00260v2
2019-12-17
Comment on "On the Origin of Frictional Energy Dissipation"
In their interesting study (Ref. [1]) Hu et al have shown that for a simple "harmonium" solid model the slip-induced motion of surface atoms is close to critically damped. This result is in fact well known from studies of vibrational damping of atoms and molecules at surfaces. However, for real practical cases the situ...
1912.07799v1
2020-01-23
Nonlinear inviscid damping for a class of monotone shear flows in finite channel
We prove the nonlinear inviscid damping for a class of monotone shear flows in $T\times [0,1]$ for initial perturbation in Gevrey-$1/s$($s>2$) class with compact support. The main idea of the proof is to use the wave operator of a slightly modified Rayleigh operator in a well chosen coordinate system.
2001.08564v1
2020-02-26
Bistability in the dissipative quantum systems I: Damped and driven nonlinear oscillator
We revisit quantum dynamics of the damped and driven nonlinear oscillator. In the classical case this system has two stationary solutions (the limit cycles) in the certain parameter region, which is the origin of the celebrated bistability phenomenon. The quantum-classical correspondence for the oscillator dynamics is ...
2002.11373v1
2020-04-08
Scattering and asymptotic order for the wave equations with the scale-invariant damping and mass
We consider the linear wave equation with the time-dependent scale-invariant damping and mass. We also treat the corresponding equation with the energy critical nonlinearity. Our aim is to show that the solution scatters to a modified linear wave solution and to obtain its asymptotic order.
2004.03832v2
2020-04-24
Infinite energy solutions for weakly damped quintic wave equations in $\mathbb{R}^3$
The paper gives a comprehensive study of infinite-energy solutions and their long-time behavior for semi-linear weakly damped wave equations in $\mathbb{R}^3$ with quintic nonlinearities. This study includes global well-posedness of the so-called Shatah-Struwe solutions, their dissipativity, the existence of a locally ...
2004.11864v1
2020-07-30
Delta shock solution to the generalized one-dimensional zero-pressure gas dynamics system with linear damping
In this paper, we propose a time-dependent viscous system and by using the vanishing viscosity method we show the existence of delta shock solution for a particular $2 \times 2$ system of conservation laws with linear damping.
2007.15184v2
2020-08-06
On global attractors for 2D damped driven nonlinear Schrödinger equations
Well-posedness and global attractor are established for 2D damped driven nonlinear Schr\"odinger equation with almost periodic pumping in a bounded region. The key role is played by a novel application of the energy equation.
2008.02741v1
2020-08-30
Influence of dissipation on extreme oscillations of a forced anharmonic oscillator
Dynamics of a periodically forced anharmonic oscillator (AO) with cubic nonlinearity, linear damping, and nonlinear damping, is studied. To begin with, the authors examine the dynamics of an AO. Due to this symmetric nature, the system has two neutrally stable elliptic equilibrium points in positive and negative potent...
2008.13172v1
2020-09-18
Vanishing viscosity limit for Riemann solutions to a $2 \times 2$ hyperbolic system with linear damping
In this paper, we propose a time-dependent viscous system and by using the vanishing viscosity method we show the existence of %delta shock solution solutions for the Riemann problem to a particular $2 \times 2$ system of conservation laws with linear damping.
2009.09041v1
2020-11-28
A Smoluchowski-Kramers approximation for an infinite dimensional system with state-dependent damping
We study the validity of a Smoluchowski-Kramers approximation for a class of wave equations in a bounded domain of $\mathbb{R}^n$ subject to a state-dependent damping and perturbed by a multiplicative noise. We prove that in the small mass limit the solution converges to the solution of a stochastic quasilinear parabol...
2011.14236v2
2020-12-13
Uniform Stabilization of the Petrovsky-Wave Nonlinear coupled system with strong damping
This paper concerns the well-posedness and uniform stabilization of the Petrovsky-Wave Nonlinear coupled system with strong damping. Existence of global weak solutions for this problem is established by using the Galerkin method. Meanwhile, under a clever use of the multiplier method, we estimate the total energy decay...
2012.07109v3
2021-03-24
On the long-time statistical behavior of smooth solutions of the weakly damped, stochastically-driven KdV equation
This paper considers the damped periodic Korteweg-de Vries (KdV) equation in the presence of a white-in-time and spatially smooth stochastic source term and studies the long-time behavior of solutions. We show that the integrals of motion for KdV can be exploited to prove regularity and ergodic properties of invariant ...
2103.12942v2
2021-04-21
On absorbing set for 3D Maxwell--Schrödinger damped driven equations in bounded region
We consider the 3D damped driven Maxwell--Schr\"odinger equations in a bounded region under suitable boundary conditions. We establish new a priori estimates, which provide the existence of global finite energy weak solutions and bounded absorbing set. The proofs rely on the Sobolev type estimates for magnetic Schr\"od...
2104.10723v1
2021-06-23
Pitt inequality for the linear structurally damped $σ$-evolution equations
This work is devoted to improve the time decay estimates for the solution and some of its derivatives of the linear structurally damped $\sigma$-evolution equations. The Pitt inequality is the main tool provided that the initial data lies in some weighted spaces.
2106.12342v1
2021-07-22
Dimension estimates for the attractor of the regularized damped Euler equations on the sphere
We prove existence of the global attractor of the damped and driven Euler--Bardina equations on the 2D sphere and on arbitrary domains on the sphere and give explicit estimates of its fractal dimension in terms of the physical parameters.
2107.10779v1
2021-09-22
State-space representation of Matérn and Damped Simple Harmonic Oscillator Gaussian processes
Gaussian processes (GPs) are used widely in the analysis of astronomical time series. GPs with rational spectral densities have state-space representations which allow O(n) evaluation of the likelihood. We calculate analytic state space representations for the damped simple harmonic oscillator and the Mat\'ern 1/2, 3/2...
2109.10685v1
2021-10-21
Stability properties of dissipative evolution equations with nonautonomous and nonlinear damping
In this paper, we obtain some stability results of (abstract) dissipative evolution equations with a nonautonomous and nonlinear damping using the exponential stability of the retrograde problem with a linear and autonomous feedback and a comparison principle. We then illustrate our abstract statements for different co...
2110.11122v1
2021-11-23
Logistic damping effect in chemotaxis models with density-suppressed motility
This paper is concerned with a parabolic-elliptic chemotaxis model with density-suppressed motility and general logistic source in an $n$-dimensional smooth bounded domain with Neumann boundary conditions. Under the minimal conditions for the density-suppressed motility function, we explore how strong the logistic damp...
2111.11669v1
2022-01-04
Global existence and decay estimates for a viscoelastic plate equation with nonlinear damping and logarithmic nonlinearity
In this article, we consider a viscoelastic plate equation with a logarithmic nonlinearity in the presence of nonlinear frictional damping term. Using the the Faedo-Galerkin method we establish the global existence of the solution of the problem and we also prove few general decay rate results.
2201.00983v1
2022-01-20
Long Time Decay of Leray Solution of 3D-NSE With Damping
In \cite{CJ}, the authors show that the Cauchy problem of the Navier-Stokes equations with damping $\alpha|u|^{\beta-1}u(\alpha>0,\;\beta\geq1)$ has global weak solutions in $L^2(\R^3)$. In this paper, we prove the uniqueness, the continuity in $L^2$ for $\beta>3$, also the large time decay is proved for $\beta\geq\fra...
2201.08427v1
2022-02-20
On a non local non-homogeneous fractional Timoshenko system with frictional and viscoelastic damping terms
We are devoted to the study of a nonhomogeneous time-fractional Timoshenko system with frictional and viscoelastic damping terms. We are concerned with the well-posedness of the given problem. The approach relies on some functional-analysis tools, operator theory, a prori estimates, and density arguments.
2202.09879v1
2022-04-05
Large time behavior of solutions to nonlinear beam equations
In this note we analyze the large time behavior of solutions to a class of initial/boundary problems involving a damped nonlinear beam equation. We show that under mild conditions on the damping term of the equation of motions the solutions of the dynamical problem converge to the solution of the stationary problem. We...
2204.02151v1
2022-05-09
Energy asymptotics for the strongly damped Klein-Gordon equation
We consider the strongly damped Klein Gordon equation for defocusing nonlinearity and we study the asymptotic behaviour of the energy for periodic solutions. We prove first the exponential decay to zero for zero mean solutions. Then, we characterize the limit of the energy, when the time tends to infinity, for solution...
2205.04205v1
2022-06-07
Asymptotic study of Leray Solution of 3D-NSE With Exponential Damping
We study the uniqueness, the continuity in $L^2$ and the large time decay for the Leray solutions of the $3D$ incompressible Navier-Stokes equations with the nonlinear exponential damping term $a (e^{b |u|^{\bf 2}}-1)u$, ($a,b>0$) studied by the second author in \cite{J1}.
2206.03138v1
2022-06-25
Decay estimate in a viscoelastic plate equation with past history, nonlinear damping, and logarithmic nonlinearity
In this article, we consider a viscoelastic plate equation with past history, nonlinear damping, and logarithmic nonlinearity. We prove explicit and general decay rate results of the solution to the viscoelastic plate equation with past history. Convex properties, logarithmic inequalities, and generalised Young's inequ...
2206.12561v1
2022-09-07
Blow up and lifespan estimates for systems of semi-linear wave equations with dampings and potentials
In this paper, we consider the semi-linear wave systems with power-nonlinearities and space-dependent dampings and potentials. We obtain the blow-up regions for three types wave systems as well as the lifespan estimates.
2209.02920v1
2022-12-14
Gevrey regularity for the Euler-Bernoulli beam equation with localized structural damping
We study a Euler-Bernoulli beam equation with localized discontinuous structural damping. As our main result, we prove that the associated $C_0$-semigroup $(S(t))_{t\geq0}$ is of Gevrey class $\delta>24$ for $t>0$, hence immediately differentiable. Moreover, we show that $(S(t))_{t\geq0}$ is exponentially stable.
2212.07110v1
2022-12-28
On extended lifespan for 1d damped wave equation
In this manuscript, a sharp lifespan estimate of solutions to semilinear classical damped wave equation is investigated in one dimensional case, when the sum of initial position and speed is $0$ pointwisely. Especially, an extension of lifespan is shown in this case. Moreover, existence of some global solutions are obt...
2212.13845v1
2023-02-06
Uniform stabilization of an acoustic system
We study the problem of stabilization for the acoustic system with a spatially distributed damping. With imposing hypothesis on the structural properties of the damping term, we identify exponential decay of solutions with growing time.
2302.02726v1
2023-05-22
Fast energy decay for wave equation with a monotone potential and an effective damping
We consider the total energy decay of the Cauchy problem for wave equations with a potential and an effective damping. We treat it in the whole one-dimensional Euclidean space. Fast energy decay is established with the help of potential. The proofs of main results rely on a multiplier method and modified techniques ado...
2305.12666v1
2023-08-03
Blow-up for semilinear wave equations with damping and potential in high dimensional Schwarzschild spacetime
In this work, we study the blow up results to power-type semilinear wave equation in the high dimensional Schwarzschild spacetime, with damping and potential terms. We can obtain the upper bound estimates of lifespan without the assumption that the support of the initial date should be far away from the black hole.
2308.01691v1
2023-08-22
Lifespan estimates for 1d damped wave equation with zero moment initial data
In this manuscript, a sharp lifespan estimate of solutions to semilinear classical damped wave equation is investigated in one dimensional case when the Fourier 0th moment of sum of initial position and speed is $0$. Especially, it is shown that the behavior of lifespan changes with $p=3/2$ with respect to the size of ...
2308.11113v1
2023-09-01
Damped Euler system with attractive Riesz interaction forces
We consider the barotropic Euler equations with pairwise attractive Riesz interactions and linear velocity damping in the periodic domain. We establish the global-in-time well-posedness theory for the system near an equilibrium state. We also analyze the large-time behavior of solutions showing the exponential rate of ...
2309.00210v1
2023-10-02
The damped wave equation and associated polymer
Considering the damped wave equation with a Gaussian noise $F$ where $F$ is white in time and has a covariance function depending on spatial variables, we will see that this equation has a mild solution which is stationary in time $t$. We define a weakly self-avoiding polymer with intrinsic length $J$ associated to thi...
2310.01631v1
2023-10-17
Indirect boundary stabilization for weakly coupled degenerate wave equations under fractional damping
In this paper, we consider the well-posedness and stability of a one-dimensional system of degenerate wave equations coupled via zero order terms with one boundary fractional damping acting on one end only. We prove optimal polynomial energy decay rate of order $1/t^{(3-\tau)}$. The method is based on the frequency dom...
2310.11174v1
2024-03-11
Uniform estimates for solutions of nonlinear focusing damped wave equations
For a damped wave (or Klein-Gordon) equation on a bounded domain, with a focusing power-like nonlinearity satisfying some growth conditions, we prove that a global solution is bounded in the energy space, uniformly in time. Our result applies in particular to the case of a cubic equation on a bounded domain of dimensio...
2403.06541v1
1995-10-27
A modified R1 X R1 method for helioseismic rotation inversions
We present an efficient method for two dimensional inversions for the solar rotation rate using the Subtractive Optimally Localized Averages (SOLA) method and a modification of the R1 X R1 technique proposed by Sekii (1993). The SOLA method is based on explicit construction of averaging kernels similar to the Backus-Gi...
9510143v1
1997-10-22
Globular Cluster Microlensing: Globular Clusters as Microlensing Targets
We investigate the possibility of using globular clusters as targets for microlensing searches. Such searches will be challenging and require more powerful telescopes than now employed, but are feasible in the 0 future. Although expected event rates are low, we show that the wide variety of lines of sight to globular c...
9710251v1
2002-12-17
An Intrinsic Baldwin Effect in the H-beta Broad Emission Line in the Spectrum of NGC 5548
We investigate the possibility of an intrinsic Baldwin Effect (i.e.,nonlinear emission-line response to continuum variations) in the broad H-beta emission line of the active galaxy NGC 5548 using cross-correlation techniques to remove light travel-time effects from the data. We find a nonlinear relationship between the...
0212379v1
2002-12-28
Detecting supersymmetric dark matter in M31 with CELESTE ?
It is widely believed that dark matter exists within galaxies and clusters of galaxies. Under the assumption that this dark matter is composed of the lightest, stable supersymmetric particle, assumed to be the neutralino, the feasibility of its indirect detection via observations of a diffuse gamma-ray signal due to ne...
0212560v1
2003-03-18
Model-Independent Reionization Observables in the CMB
We represent the reionization history of the universe as a free function in redshift and study the potential for its extraction from CMB polarization spectra. From a principal component analysis, we show that the ionization history information is contained in 5 modes, resembling low-order Fourier modes in redshift spac...
0303400v1
2006-05-08
Discovery of an Extended Halo of Metal-poor Stars in the Andromeda Spiral Galaxy
This paper has been withdrawn. Please see astro-ph/0502366.
0605172v3
1995-01-02
Dynamics of homogeneous magnetizations in strong transverse driving fields
Spatially homogeneous solutions of the Landau--Lifshitz--Gilbert equation are analysed. The conservative as well as the dissipative case is considered explicitly. For the linearly polarized driven Hamiltonian system we apply canonical perturbation theory to uncover the main resonances as well as the global phase space ...
9501002v1
2000-09-18
Electronic properties of the degenerate Hubbard Model : A dynamical mean field approach
We have investigated electronic properties of the degenerate multi-orbital Hubbard model, in the limit of large spatial dimension. A new local model, including a doubly degenerate strongly correlated site has been introduced and solved in the framework of the non-crossing approximation (NCA). Mott-Hubbard transitions h...
0009253v1
2001-01-11
Theoretical and Experimental Approach to Spin Dynamics in Thin Magnetic Films
The Landau-Lifshitz (L-L) equation describing the time dependence of the magnetisation vector is numerically integrated fully without any simplifying assumptions in the time domain and the magnetisation time series obtained is Fourier transformed (FFT) to yield the permeability spectrum up to 10 GHz. The non linear res...
0101154v1
2004-08-13
Finite lattice size effect in the ground state phase diagram of quasi-two-dimensional magnetic dipolar dots array with perpendicular anisotropy
A prototype Hamiltonian for the generic patterned magnetic structures, of dipolar interaction with perpendicular anisotropy, is investigated within the finite-size framework by Landau-Lifshift-Gilbert classical spin dynamics. Modifications on the ground state phase diagram are discussed with an emphasis on the disappea...
0408324v1
2004-10-01
Current-spin coupling for ferromagnetic domain walls in fine wires
The coupling between a current and a domain wall is examined. In the presence of a finite current and the absence of a potential which breaks the translational symmetry, there is a perfect transfer of angular momentum from the conduction electrons to the wall. As a result, the ground state is in uniform motion. This re...
0410035v1
2004-12-17
Hysteresis loops of magnetic thin films with perpendicular anisotropy
We model the magnetization of quasi two-dimensional systems with easy perpendicular (z-)axis anisotropy upon change of external magnetic field along z. The model is derived from the Landau-Lifshitz-Gilbert equation for magnetization evolution, written in closed form in terms of the z component of the magnetization only...
0412461v1
2006-01-11
Relaxing-Precessional Magnetization Switching
A new way of magnetization switching employing both the spin-transfer torque and the torque by a magnetic field is proposed. The solution of the Landau-Lifshitz-Gilbert equation shows that the dynamics of the magnetization in the initial stage of the switching is similar to that in the precessional switching, while tha...
0601227v1
2006-04-01
Magnetization reversal through synchronization with a microwave
Based on the Landau-Lifshitz-Gilbert equation, it can be shown that a circularly-polarized microwave can reverse the magnetization of a Stoner particle through synchronization. In comparison with magnetization reversal induced by a static magnetic field, it can be shown that when a proper microwave frequency is used th...
0604013v1
2006-06-26
Self Consistent NEGF-LLG Model for Spin-Torque Based Devices
We present here a self consistent solution of quantum transport, using the Non Equilibrium Green's Function (NEGF) method, and magnetization dynamics, using the Landau-Lifshitz-Gilbert (LLG) formulation. We have applied this model to study current induced magnetic switching due to `spin torque' in a device where the el...
0606648v2
2006-07-25
Thermally-Assisted Current-Driven Domain Wall Motion
Starting from the stochastic Landau-Lifschitz-Gilbert equation, we derive Langevin equations that describe the nonzero-temperature dynamics of a rigid domain wall. We derive an expression for the average drift velocity of the domain wall as a function of the applied current, and find qualitative agreement with recent m...
0607663v1
2006-09-08
Large cone angle magnetization precession of an individual nanomagnet with dc electrical detection
We demonstrate on-chip resonant driving of large cone-angle magnetization precession of an individual nanoscale permalloy element. Strong driving is realized by locating the element in close proximity to the shorted end of a coplanar strip waveguide, which generates a microwave magnetic field. We used a microwave frequ...
0609190v1
2006-12-30
Low relaxation rate in a low-Z alloy of iron
The longest relaxation time and sharpest frequency content in ferromagnetic precession is determined by the intrinsic (Gilbert) relaxation rate \emph{$G$}. For many years, pure iron (Fe) has had the lowest known value of $G=\textrm{57 Mhz}$ for all pure ferromagnetic metals or binary alloys. We show that an epitaxial i...
0701004v1
2004-09-07
Distance properties of expander codes
We study the minimum distance of codes defined on bipartite graphs. Weight spectrum and the minimum distance of a random ensemble of such codes are computed. It is shown that if the vertex codes have minimum distance $\ge 3$, the overall code is asymptotically good, and sometimes meets the Gilbert-Varshamov bound. Co...
0409010v1
1996-06-11
Radiative corrections to $e^+e^-\to H^+ H^-$
We study the 1-loop corrections to the charged Higgs production both in the Minimal Supersymmetric Standard Model (MSSM) and in a more general type II two-Higgs-doublet model (THDM-II). We consider the full set of corrections (including soft photon contributions as well as box diagrams), and define a parametrization th...
9606300v1
1997-05-15
Analytic constraints from electroweak symmetry breaking in the MSSM
We report on how a straightforward (albeit technically involved) analytic study of the 1-loop effective potential in the Minimal Supersymmetric Standard Model, modifies the usual electroweak symmetry breaking conditions involving $\tan \beta$ and the other free parameters of the model. The study implies new constraints...
9705330v1
1998-10-01
Extracting chargino/neutralino mass parameters from physical observables
I report on two papers, hep-ph/9806279 and hep-ph/9807336, where complementary strategies are proposed for the determination of the chargino/neutralino sector parameters, $M_1, M_2, \mu $ and $\tan \beta$, from the knowledge of some physical observables. This determination and the occurrence of possible ambiguities are...
9810214v1
1999-12-28
Associated H$^{-}$ W$^{+}$ Production in High Energy $e^+e^-$ Collisions
We study the associated production of charged Higgs bosons with $W$ gauge bosons in high energy $e^+ e^-$ collisions at the one loop level. We present the analytical results and give a detailed discussion for the total cross section predicted in the context of a general Two Higgs Doublet Model (THDM).
9912527v2
2001-03-25
Comment on ``Infrared Fixed Point Structure in Minimal Supersymmetric Standard Model with Baryon and Lepton Number Violation"
We reconsider the Infrared Quasi Fixed Points which were studied recently in the literature in the context of the Baryon and Lepton number violating Minimal Supersymmetric Standard Model (hep-ph/0011274). The complete analysis requires further care and reveals more structure than what was previously shown. The formalis...
0103270v1
1991-11-21
"the Instability of String-Theoretic Black Holes"
It is demonstrated that static, charged, spherically--symmetric black holes in string theory are classically and catastrophically unstable to linearized perturbations in four dimensions, and moreover that unstable modes appear for arbitrarily small positive values of the charge. This catastrophic classical instability ...
9111042v1
1997-12-09
The combinatorics of biased riffle shuffles
This paper studies biased riffle shuffles, first defined by Diaconis, Fill, and Pitman. These shuffles generalize the well-studied Gilbert-Shannon-Reeds shuffle and convolve nicely. An upper bound is given for the time for these shuffles to converge to the uniform distribution; this matches lower bounds of Lalley. A ca...
9712240v1
2000-08-16
Homotopies and automorphisms of crossed modules of groupoids
We give a detailed description of the structure of the actor 2-crossed module related to the automorphisms of a crossed module of groupoids. This generalises work of Brown and Gilbert for the case of crossed modules of groups, and part of this is needed for work on 2-dimensional holonomy to be developed elsewhere (see ...
0008117v2
2005-06-14
Transitive and Self-dual Codes Attaining the Tsfasman-Vladut-Zink Bound
We introduce - as a generalization of cyclic codes - the notion of transitive codes, and we show that the class of transitive codes is asymptotically good. Even more, transitive codes attain the Tsfasman-Vladut-Zink bound over F_q, for all aquares q=l^2. We also show that self-orthogonal and self-dual codes attain the ...
0506264v1
2005-09-01
Counting unlabelled toroidal graphs with no K33-subdivisions
We provide a description of unlabelled enumeration techniques, with complete proofs, for graphs that can be canonically obtained by substituting 2-pole networks for the edges of core graphs. Using structure theorems for toroidal and projective-planar graphs containing no K33-subdivisions, we apply these techniques to o...
0509004v2
2006-05-19
Deformation spaces of trees
Let G be a finitely generated group. Two simplicial G-trees are said to be in the same deformation space if they have the same elliptic subgroups (if H fixes a point in one tree, it also does in the other). Examples include Culler-Vogtmann's outer space, and spaces of JSJ decompositions. We discuss what features are co...
0605545v2
1999-10-12
Uniform spectral properties of one-dimensional quasicrystals, III. $α$-continuity
We study the spectral properties of discrete one-dimensional Schr\"odinger operators with Sturmian potentials. It is shown that the point spectrum is always empty. Moreover, for rotation numbers with bounded density, we establish purely $\alpha$-continuous spectrum, uniformly for all phases. The proofs rely on the uniq...
9910017v1
2003-08-18
Vector Coherent States on Clifford algebras
The well-known canonical coherent states are expressed as an infinite series in powers of a complex number $z$ together with a positive sequence of real numbers $\rho(m)=m$. In this article, in analogy with the canonical coherent states, we present a class of vector coherent states by replacing the complex variable $z$...
0308020v2
2007-01-12
Non-equilibrium Lorentz gas on a curved space
The periodic Lorentz gas with external field and iso-kinetic thermostat is equivalent, by conformal transformation, to a billiard with expanding phase-space and slightly distorted scatterers, for which the trajectories are straight lines. A further time rescaling allows to keep the speed constant in that new geometry. ...
0701024v1
2006-02-23
Equivalence of two mathematical forms for the bound angular momentum of the electromagnetic field
It is shown that the mathematical form, obtained in a recent paper, for the angular momentum of the electromagnetic field in the vicinity of electric charge is equivalent to another form obtained previously by Cohen-Tannoudji, Dupont-Roc and Gilbert. In this version of the paper an improved derivation is given.
0602157v3
2006-10-13
Senescence Can Explain Microbial Persistence
It has been known for many years that small fractions of persister cells resist killing in many bacterial colony-antimicrobial confrontations. These persisters are not believed to be mutants. Rather it has been hypothesized that they are phenotypic variants. Current models allow cells to switch in and out of the persis...
0610026v1
2002-12-30
Dark propagation modes in optical lattices
We examine the stimulated light scattering onto the propagation modes of a dissipative optical lattice. We show that two different pump-probe configurations may lead to the excitation, via different mechanisms, of the same mode. We found that in one configuration the scattering on the propagation mode results in a reso...
0212157v1
2003-09-29
Phase-control of directed diffusion in a symmetric optical lattice
We demonstrate the phenomenon of directed diffusion in a symmetric periodic potential. This has been realized with cold atoms in a one-dimensional dissipative optical lattice. The stochastic process of optical pumping leads to a diffusive dynamics of the atoms through the periodic structure, while a zero-mean force whi...
0309208v1
2003-09-29
Synchronization of Hamiltonian motion and dissipative effects in optical lattices: Evidence for a stochastic resonance
We theoretically study the influence of the noise strength on the excitation of the Brillouin propagation modes in a dissipative optical lattice. We show that the excitation has a resonant behavior for a specific amount of noise corresponding to the precise synchronization of the Hamiltonian motion on the optical poten...
0309210v1
2006-06-23
Playing Quantum Physics Jeopardy with zero-energy eigenstates
We describe an example of an exact, quantitative Jeopardy-type quantum mechanics problem. This problem type is based on the conditions in one-dimensional quantum systems that allow an energy eigenstate for the infinite square well to have zero curvature and zero energy when suitable Dirac delta functions are added. Thi...
0606196v1
2006-10-18
Subsystem Codes
We investigate various aspects of operator quantum error-correcting codes or, as we prefer to call them, subsystem codes. We give various methods to derive subsystem codes from classical codes. We give a proof for the existence of subsystem codes using a counting argument similar to the quantum Gilbert-Varshamov bound....
0610153v1
2007-05-14
The dynamical response to the node defect in thermally activated remagnetization of magnetic dot array
The influence of nonmagnetic central node defect on dynamical properties of regular square-shaped 5 x 5 segment of magnetic dot array under the thermal activation is investigated via computer simulations. Using stochastic Landau-Lifshitz-Gilbert equation we simulate hysteresis and relaxation processes. The remarkable q...
0705.1889v1
2007-05-18
Steady-state conduction in self-similar billiards
The self-similar Lorentz billiard channel is a spatially extended deterministic dynamical system which consists of an infinite one-dimensional sequence of cells whose sizes increase monotonically according to their indices. This special geometry induces a nonequilibrium stationary state with particles flowing steadily ...
0705.2758v1
2007-06-04
Generation of microwave radiation in planar spin-transfer devices
Current induced precession states in spin-transfer devices are studied in the case of large easy plane anisotropy (present in most experimental setups). It is shown that the effective one-dimensional planar description provides a simple qualitative understanding of the emergence and evolution of such states. Switching ...
0706.0529v1
2007-12-26
Mass and angular-momentum inequalities for axi-symmetric initial data sets. II. Angular-momentum
We extend the validity of Dain's angular-momentum inequality to maximal, asymptotically flat, initial data sets on a simply connected manifold with several asymptotically flat ends which are invariant under a U(1) action and which admit a twist potential.
0712.4064v2
2008-01-28
TER: A Robot for Remote Ultrasonic Examination: Experimental Evaluations
This chapter: o Motivates the clinical use of robotic tele-echography o Introduces the TER system o Describes technical and clinical evaluations performed with TER
0801.4355v1
2008-03-14
Spin-torque shot noise in magnetic tunnel junctions
Spin polarized current may transfer angular momentum to a ferromagnet, resulting in a spin-torque phenomenon. At the same time the shot noise, associated with the current, leads to a non-equilibrium stochastic force acting on the ferromagnet. We derive stochastic version of Landau-Lifshitz-Gilbert equation for a magnet...
0803.2101v1
2008-04-07
Paired Orbitals for Different Spins equations
Eigenvalue-type equations for Lowdin-Amos-Hall spin-paired (corresponding) orbitals are developed to provide an alternative to the standard spin-polarized Hartree-Fock or Kohn-Sham equations. Obtained equations are non-canonical unrestricted Hartree-Fock-type equations in which non-canonical orbitals are fixed to be bi...
0804.0967v1
2008-04-26
Spin-torque oscillator based on tilted magnetization of the fixed layer
The spin torque oscillator (STO), where the magnetization of the fixed layer is tilted out of the film plane, is capable of strong microwave signal generation in zero magnetic field. Through numerical simulations of the Landau-Lifshitz-Gilbert-Slonczewski equations, within a macro-spin approximation, we study the micro...
0804.4213v1
2008-07-11
Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures
We report the discovery of superconductivity at high pressure in SrFe2As2 and BaFe2As2. The superconducting transition temperatures are up to 27 K in SrFe2As2 and 29 K in BaFe2As2, making these the highest pressure-induced superconducting materials discovered thus far.
0807.1896v2
2008-07-14
An Adaptive Entanglement Distillation Scheme Using Quantum Low Density Parity Check Codes
Quantum low density parity check (QLDPC) codes are useful primitives for quantum information processing because they can be encoded and decoded efficiently. Besides, the error correcting capability of a few QLDPC codes exceeds the quantum Gilbert-Varshamov bound. Here, we report a numerical performance analysis of an a...
0807.2122v1
2008-07-16
Analytical solution of the equation of motion for a rigid domain wall in a magnetic material with perpendicular anisotropy
This paper reports the solution of the equation of motion for a domain wall in a magnetic material which exhibits high magneto-crystalline anisotropy. Starting from the Landau-Lifschitz-Gilbert equation for field-induced motion, we solve the equation to give an analytical expression, which specifies the domain wall pos...
0807.2604v3
2008-07-16
A graphical extension for the Windows version of the Parallel Finite Element Micromagnetics Package (MagParExt)
In the current paper we present a graphical user interface useful for settings input parameter of the Windows precompiled binaries for the Parallel Finite Element Micromagnetics Package (MagPar). The Package is used for magnetization dynamics analysis on a base of the Landau-Lifshitz-Gilbert (LLG) equation. In an avail...
0807.2655v1
2008-08-17
Attempt frequency of magnetization in nanomagnets with thin-film geometry
Solving the stochastic Landau-Lifshitz-Gilbert equation numerically, we investigate the effect of the potential landscape on the attempt frequency of magnetization in nanomagnets with the thin-film geometry. Numerical estimates of the attempt frequency are analyzed in comparison with theoretical predictions from the Fo...
0808.2281v1
2008-08-30
Path integral study of the role of correlation in exchange coupling of spins in double quantum dots and optical lattices
We explore exchange coupling of a pair of spins in a double dot and in an optical lattice. Our algorithm uses the frequency of exchanges in a bosonic path integral, evaluated with Monte Carlo. This algorithm is simple enough to be a "black box" calculator, yet gives insights into the role of correlation through two-par...
0809.0038v1