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In this paper we develop a model to describe the diffusion process in a porous medium. For the observed decrease in current yield, we propose other causes than difference in diffusivity, which we consider unaltered by the porous medium. The…

Chemical Physics · Physics 2012-05-10 P. C. T. DÁjello , G. L. Nunes , J. J. Piacentini , L. Lauck

We consider the diffusion of markers in a layered medium, with the lateral diffusion coefficient being the function of hight. We show that the probability density of the lateral displacements follows one-dimensional Batchelor's equation…

Mesoscale and Nanoscale Physics · Physics 2014-04-28 Eugene B. Postnikov , Igor M. Sokolov

We discuss diffusion of particles in a spatially inhomogeneous medium. From the microscopic viewpoint we consider independent particles randomly evolving on a lattice. We show that the reversibility condition has a discrete geometric…

Statistical Mechanics · Physics 2018-11-14 Daniele Andreucci , Emilio N. M. Cirillo , Matteo Colangeli , Davide Gabrielli

This paper considers the problem of regression analysis with random covariance matrix as outcome and Euclidean covariates in the framework of Fr\'echet regression on the Bures-Wasserstein manifold. Such regression problems have many…

Methodology · Statistics 2024-09-17 Haoshu Xu , Hongzhe Li

The scaling invariance for chaotic orbits near a transition from unlimited to limited diffusion in a dissipative standard mapping is explained via the analytical solution of the diffusion equation. It gives the probability of observing a…

Chaotic Dynamics · Physics 2020-12-02 Edson D. Leonel , Celia Mayumi Kuwana , Makoto Yoshida , Juliano Antonio de Oliveira

In this paper we introduce a new approach to the diffusive limit of the weakly random Schrodinger equation, first studied by L. Erdos, M. Salmhofer, and H.T. Yau. Our approach is based on a wavepacket decomposition of the evolution…

Mathematical Physics · Physics 2024-12-11 Felipe Hernández

We derive an anomalous, sub-diffusive scaling limit for a one-dimensional version of the Mott random walk. The limiting process can be viewed heuristically as a one-dimensional diffusion with an absolutely continuous speed measure and a…

Probability · Mathematics 2024-04-19 David A. Croydon , Ryoki Fukushima , Stefan Junk

We review our proof that in a scaling limit, the time evolution of a quantum particle in a static random environment leads to a diffusion equation. In particular, we discuss the role of Feynman graph expansions and of renormalization.

Mathematical Physics · Physics 2008-07-01 Laszlo Erdoes , Manfred Salmhofer , Horng-Tzer Yau

Employing a phase space which includes the (Riemann-Liouville) fractional derivative of curves evolving on real space, we develop a restricted variational principle for Lagrangian systems yielding the so-called restricted fractional…

Mathematical Physics · Physics 2018-03-01 Fernando Jiménez , Sina Ober-Blöbaum

We expand the classic variational formulation of $-\log\mathbb{E}\left[e^{-f}\right]$ to the case where f depends on a diffusion, and not only a on Brownian motion, while decreasing the integrability hypothesis on f. We also give an…

Probability · Mathematics 2016-12-02 Kévin Hartmann

We analyze spreading of a density front in the K\"untz-Lavall\'ee model of porous media. In contrast to previous studies, where unusual properties of the front were attributed to anomalous diffusion, we find that the front evolution is…

Fluid Dynamics · Physics 2009-11-13 Maciej Matyka , Zbigniew Koza

Practical diffusion sampling is a numerical approximation problem: under a fixed inference budget, one must simulate a reverse-time ODE or SDE using only a limited number of denoising steps, so discretization error is often the dominant…

Machine Learning · Computer Science 2026-05-12 Samuel Hurault , Thomas Moreau , Gabriel Peyré

We investigate the asymptotic behavior, in the long time limit, of the random homology associated to realizations of stochastic diffusion processes on a compact Riemannian manifold. In particular a rigidity result is established: if the…

Probability · Mathematics 2024-06-26 Artem Galkin , Mauro Mariani

We study the small-time asymptotics for hypoelliptic diffusion processes conditioned by their initial and final positions, in a model class of diffusions satisfying a weak H\"ormander condition where the diffusivity is constant and the…

Probability · Mathematics 2019-02-20 Karen Habermann

We study the problem of the computation of the effective diffusion constant of a Brownian particle diffusing in a random potential which is given by a function $V(\phi)$ of a Gaussian field $\phi$. A self similar renormalization group…

Statistical Mechanics · Physics 2009-01-27 David S. Dean , Clement Touya

Diffusion is a fundamental physical phenomenon with critical applications in fields such as metallurgy, cell biology, and population dynamics. While standard diffusion is well-understood, anomalous diffusion often requires complex non-local…

Statistical Mechanics · Physics 2026-01-16 Gabriel Barreiro , Vladimir Pérez-Veloz

Diffusion magnetic resonance imaging (dMRI) is a relatively modern technique used to study tissue microstructure in a non-invasive way. Non-Gaussian diffusion representation is related to the restricted diffusion and can provide information…

Signal Processing · Electrical Eng. & Systems 2020-09-17 Tomasz Pieciak , Maryam Afzali , Fabian Bogusz , Aja-Fernández , Derek K. Jones

Diffusion models excel in content generation by implicitly learning the data manifold, yet they lack a practical method to leverage this manifold - unlike other deep generative models equipped with latent spaces. This paper introduces a…

Computer Vision and Pattern Recognition · Computer Science 2025-04-30 Shinnosuke Saito , Takashi Matsubara

Exact results of the finite-size behavior of the susceptibility in three-dimensional mean spherical model films under Dirichlet-Dirichlet, Dirichlet-Neumann and Neumann-Neumann boundary conditions are presented. The corresponding scaling…

Statistical Mechanics · Physics 2009-11-10 Daniel M. Dantchev , Jordan G. Brankov

Using coherent-state techniques, we prove a sampling theorem for Majorana's (holomorphic) functions on the Riemann sphere and we provide an exact reconstruction formula as a convolution product of $N$ samples and a given reconstruction…

Mathematical Physics · Physics 2011-09-13 Manuel Calixto , Julio Guerrero , Juan Carlos Sánchez-Monreal