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We investigate Brownian motion with diffusivity alternately fluctuating between fast and slow states. We assume that sojourn-time distributions of these two states are given by exponential or power-law distributions. We develop a theory of…

Statistical Mechanics · Physics 2019-07-17 Tomoshige Miyaguchi , Takashi Uneyama , Takuma Akimoto

Fluctuation Theorems are statements about the entropy of systems far from thermal equilibrium. In this Letter relativistic Fluctuation Theorems for Brownian motion are presented and proven. Though there is a known discretization dilemma…

Statistical Mechanics · Physics 2007-05-23 Axel Fingerle

Stochastic reaction-diffusion equations are a popular modelling approach for studying interacting populations in a heterogeneous environment under the influence of environmental fluctuations. Although the theoretical basis of alternative…

Populations and Evolution · Quantitative Biology 2017-02-16 Ivo Siekmann , Michael Bengfort , Horst Malchow

The density fluctuations of nuclear matter are studied within a mean-field model in wich fluctuations are generated by an external stochastic field. The constraints imposed on the random force by the fluctuation-dissipation theorem are…

Nuclear Theory · Physics 2009-11-06 F. Matera , A. Dellafiore

We review generalized Fluctuation-Dissipation Relations which are valid under general conditions even in ``non-standard systems'', e.g. out of equilibrium and/or without a Hamiltonian structure. The response functions can be expressed in…

Statistical Mechanics · Physics 2019-09-10 A. Sarracino , A. Vulpiani

We consider the usual Langevin equation depending on an internal time. This parameter is substituted by a first passage time of a self-similar Markov process. Then the Gaussian process is parent, and the hitting time process is directing.…

Statistical Mechanics · Physics 2011-11-15 Aleksander Stanislavsky

There remains a useful relation between diffusion and mobility for a Langevin particle in a periodic medium subject to nonconservative forces. The usual fluctuation-dissipation relation easily gets modified and the mobility matrix is no…

Statistical Mechanics · Physics 2015-03-17 Marco Baiesi , Christian Maes , Bram Wynants

The Fokker-Planck equation for the probability $f(r,t)$ to find a random walker at position $r$ at time $t$ is derived for the case that the the probability to make jumps depends nonlinearly on $f(r,t)$. The result is a generalized form of…

Statistical Mechanics · Physics 2008-08-20 James F. Lutsko , Jean Pierre Boon

According to a traditional point of view Boltzmann entropy is intimately related to linear Fokker-Planck equations (Smoluchowski, Klein-Kramers, and Rayleigh equations) that describe a well-known nonequilibrium phenomenon: (normal) Brownian…

General Physics · Physics 2017-01-11 A. O. Bolivar

Based on the generalized Langevin equation for the momentum of a Brownian particle a generalized asymptotic Einstein relation is derived. It agrees with the well-known Einstein relation in the case of normal diffusion but continues to hold…

Soft Condensed Matter · Physics 2015-06-23 Hyun Kyung Shin , Bongsik Choi , Peter Talkner , Eok Kyun Lee

Fluctuations arising in nonlinear dissipative systems (diode, transistors, chemical reaction, etc.) subject to an external drive (voltage, chemical potential, etc.) are well known to elude any simple characterization such as the…

Statistical Mechanics · Physics 2023-07-10 Jean-Charles Delvenne , Léopold Van Brandt

In this article we study the trapped motion of a molecule undergoing diffusivity fluctuations inside a harmonic potential. For the same diffusing-diffusivity process, we investigate two possible interpretations. Depending on whether…

Statistical Mechanics · Physics 2023-01-04 Yann Lanoiselée , Aleksander Stanislavsky , Davide Calebiro , Aleksander Weron

Experimental and theoretical studies are made of Brownian particles trapped in a periodic potential, which is very slightly tilted due to gravity. In the presence of fluctuations, these will trigger a measurable average drift along the…

Atomic Physics · Physics 2010-10-14 M. Zelan , H. Hagman , K. Karlsson , C. M. Dion , A. Kastberg

We compare the fluctuation relations for work and entropy in underdamped and overdamped systems, when the friction coefficient of the medium is space-dependent. We find that these relations remain unaffected in both cases. However, for the…

Statistical Mechanics · Physics 2015-06-15 Sourabh Lahiri , Shubhashis Rana , A. M. Jayannavar

A Brownian particle floating in a narrow corrugated (sinusoidal) channel with fluctuating cross section exhibits non-Gaussian normal diffusion. Its displacements are distributed according to a Gaussian law for very short and asymptotically…

Statistical Mechanics · Physics 2019-10-09 Yunyun Li , Fabio Marchesoni , Debajyoti Debnath , Pulak K. Ghosh

We study the diffusive dynamics of a Brownian particle in proximity of a flat surface under non-equilibrium conditions, which are created by an anisotropic thermal environment with different temperatures being active along distinct spatial…

Statistical Mechanics · Physics 2017-09-13 Stefano Bo , Ralf Eichhorn

We derive expressions for the dispersion for two classes of random variables in Markov processes. Random variables like current and activity pertain to the first class, which is composed by random variables that change whenever a jump in…

Statistical Mechanics · Physics 2015-10-13 Andre C. Barato , Udo Seifert

We study the work fluctuations of a particle, confined to a moving harmonic potential, under the influence of friction and external Poissonian shot noise. The asymmetry of the noise induces an effective nonlinearity in the potential, which…

Statistical Mechanics · Physics 2009-11-13 A. Baule , E. G. D. Cohen

We consider a general class of nonlinear diffusive models with bulk dissipation and boundary driving, and derive its hydrodynamic description in the large size limit. Both the average macroscopic behavior and the fluctuating properties of…

Statistical Mechanics · Physics 2013-10-29 A. Prados , A. Lasanta , Pablo I. Hurtado

We construct a two-dimensional diffusion process with rank-dependent local drift and dispersion coefficients, and with a full range of patterns of behavior upon collision that range from totally frictionless interaction, to elastic…

Probability · Mathematics 2012-08-24 E. Robert Fernholz , Tomoyuki Ichiba , Ioannis Karatzas