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A Carleman estimate and the unique continuation property of solutions for a multi-terms time fractional diffusion equation up to order $\alpha\,\,(0<\alpha<2)$ and general time dependent second order strongly elliptic time elliptic operator…

Analysis of PDEs · Mathematics 2017-10-09 Ching-Lung Lin , Gen Nakamura

DNS and laboratory experiments show that the spatial distribution of straining stagnation points in homogeneous isotropic 3D turbulence has a fractal structure with dimension D_s = 2. In Kinematic Simulations the time exponent gamma in…

Fluid Dynamics · Physics 2009-11-07 Javier Davila , Christos Vassilicos

We consider a class of stochastic kinetic equations, depending on two time scale separation parameters $\epsilon$ and $\delta$: the evolution equation contains singular terms with respect to $\epsilon$, and is driven by a fast ergodic…

Probability · Mathematics 2021-06-14 Charles-Edouard Bréhier , Shmuel Rakotonirina-Ricquebourg

The spatial distribution of persistent (unvisited) sites in one dimensional $A+A\to\emptyset$ model is studied. The `empty interval distribution' $n(k,t)$, which is the probability that two consecutive persistent sites are separated by…

Statistical Mechanics · Physics 2007-05-23 G. Manoj , P. Ray

This Communication reports a geometrical factor that is necessary in the diffusion boundary condition across surface steps. Specifically, this factor relates adatom concentration to its spatial gradient at a surface step, and it describes…

Materials Science · Physics 2015-06-03 Xiaobin Niu , Hanchen Huang

In this study we present an extension of the replicator equation with diffusion to multiplex graphs. We derive an exact formula for the diffusion term, which shows that, while diffusion is linear for numbers of agents, it is necessary to…

Physics and Society · Physics 2016-08-10 Rubén J. Requejo , Albert Díaz Guilera

The paper is focused on the numerical solution of stochastic reaction-diffusion problems. A special attention is addressed to the conservation of mean-square dissipativity in the time integration of the spatially discretized problem,…

Numerical Analysis · Mathematics 2025-07-23 Helena Biščević , Raffaele D'Ambrosio

In this paper we consider the time dependent one-dimensional Schr\"odinger equation with multiple Dirac delta potentials {of different strengths}. We prove that the classical dispersion property holds under some restrictions on the…

Analysis of PDEs · Mathematics 2016-01-20 V. Banica , L. I. Ignat

In this paper the author studies the problem of the homogenization of a diffusion perturbed by a periodic reflection invariant vector field. The vector field is assumed to have fixed direction but varying amplitude. The existence of a…

Analysis of PDEs · Mathematics 2007-05-23 Joseph G. Conlon

This article concerns second-order time discretization of subdiffusion equations with time-dependent diffusion coefficients. High-order differentiability and regularity estimates are established for subdiffusion equations with…

Numerical Analysis · Mathematics 2020-06-05 Bangti Jin , Buyang Li , Zhi Zhou

We study the scale dependence of effective diffusion of fluid tracers, specifically, its dependence on the P\'{e}clet number, a dimensionless parameter of the ratio between advection and molecular diffusion. Here, we address the case that…

Fluid Dynamics · Physics 2022-04-13 Yohei Kono , Yoshihiko Susuki , Takashi Hikihara

We consider the time dependent dispersion properties of overdamped tracer particles diffusing in a one dimensional periodic potential under the influence of an additional constant tilting force $F$. The system is studied in the region where…

Statistical Mechanics · Physics 2017-02-01 T. Guérin , D. S. Dean

We study lower and upper bounds for the density of a diffusion process in ${\mathbb{R}}^n$ in a small (but not asymptotic) time, say $\delta$. We assume that the diffusion coefficients $\sigma_1,\ldots,\sigma_d$ may degenerate at the…

Probability · Mathematics 2019-12-03 Vlad Bally , Lucia Caramellino , Paolo Pigato

The diffusion equation \partial_t\phi = \nabla^2\phi is considered, with initial condition \phi( _x_ ,0) a gaussian random variable with zero mean. Using a simple approximate theory we show that the probability p_n(t_1,t_2) that \phi( _x_…

Condensed Matter · Physics 2009-10-28 Satya N. Majumdar , Clement Sire , Alan J. Bray , Stephen J. Cornell

With the help of the methods developed in our previous article [Schmitz, to appear in "Annales de l'I.H.P. Prob. & Stat.], we highlight condition (T) as a source of new examples of 'ballistic' diffusions in a random environment when d>1…

Probability · Mathematics 2007-05-23 Tom Schmitz

In this paper we investigate deterministic diffusion in systems which are spatially extended in certain directions but are restricted in size and open in other directions, consequently particles can escape. We introduce besides the…

chao-dyn · Physics 2016-08-31 Z. Kaufmann , H. Lustfeld , A. Nemeth , P. Szepfalusy

Diffusion models do not recover semantic structure uniformly over time. Instead, samples transition from semantic ambiguity to class commitment within a narrow regime. Recent theoretical work attributes this transition to dynamical…

Machine Learning · Statistics 2026-02-11 Florian Handke , Dejan Stančević , Felix Koulischer , Thomas Demeester , Luca Ambrogioni

We consider a Poisson equation in $\mathbb R^d$ for the elliptic operator corresponding to an ergodic diffusion process. Optimal regularity and smoothness with respect to the parameter are obtained under mild conditions on the coefficients.…

Probability · Mathematics 2020-09-11 Michael Röckner , Longjie Xie

To solve the obscureness in measurement brought about from the weak ergodicity breaking appeared in anomalous diffusions we have suggested the time-averaged mean squared displacement (MSD) $\bar{\delta^2 (\tau)}_\tau$ with a integral…

Statistical Mechanics · Physics 2015-06-11 Hyun-Joo Kim

Diffusion of molecules in cells plays an important role in providing a biological reaction on the surface by finding a target on the membrane surface. The water retardation (slow diffusion) near the target assists the searching molecules to…

Statistical Mechanics · Physics 2015-09-02 Takuma Akimoto , Kazuhiko Seki
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