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In this work, we consider the numerical recovery of a spatially dependent diffusion coefficient in a subdiffusion model from distributed observations. The subdiffusion model involves a Caputo fractional derivative of order $\alpha\in(0,1)$…

Numerical Analysis · Mathematics 2021-01-12 Bangti Jin , Zhi Zhou

We discuss the dynamics of particles in one dimension in potentials that are random both in space and in time. The results are applied to recent optics experiments on Anderson localization, in which the transverse spreading of a beam is…

Disordered Systems and Neural Networks · Physics 2013-08-30 Yevgeny Krivolapov , Liad Levi , Shmuel Fishman , Mordechai Segev , Michael Wilkinson

Strong anomalous diffusion is characterized by asymptotic power-law growth of the moments of displacement, with exponents that do not depend linearly on the order of the moment. The exponents concerning small-order moments are dominated by…

Statistical Mechanics · Physics 2021-01-27 Jürgen Vollmer , Lamberto Rondoni , Muhammad Tayyab , Claudio Giberti , Carlos Mejía-Monasterio

We study the long-time behavior of a particle in $\mathbb{R}^d$, $d \geq 2$, subject to molecular diffusion and advection by a random incompressible flow. The velocity field is the divergence of a stationary random stream matrix $\mathbf{k}…

Probability · Mathematics 2026-01-30 Scott Armstrong , Ahmed Bou-Rabee , Tuomo Kuusi

Denoising diffusions are a powerful method to generate approximate samples from high-dimensional data distributions. Recent results provide polynomial bounds on their convergence rate, assuming $L^2$-accurate scores. Until now, the tightest…

Machine Learning · Statistics 2024-03-07 Joe Benton , Valentin De Bortoli , Arnaud Doucet , George Deligiannidis

We investigate through a Generalized Langevin formalism the phenomenon of anomalous diffusion for asymptotic times, and we generalized the concept of the diffusion exponent. A method is proposed to obtain the diffusion coefficient…

Statistical Mechanics · Physics 2015-03-20 R. M. S. Ferreira , M. V. S. Santos , C. C. Donato , J. S. Andrade , F. A. Oliveira

Using granular experiments and computer simulations, we investigate the long-time diffusion of active tracers in a broad class of complex media composed of frozen obstacles of diverse structures. By introducing a dimensionless persistence…

Soft Condensed Matter · Physics 2025-05-06 Qun Zhang , Yuxin Tian , Xue Zhang , Xiaoting Yu , Hongwei Zhu , Ning Zheng , Luhui Ning , Ran Ni , Mingcheng Yang , Peng Liu

We study the dynamics of spin currents in the XX spin-1/2 ladder at finite temperature. Within the framework of linear response theory, we numerically calculate autocorrelation functions for quantum systems larger than what is accessible…

Strongly Correlated Electrons · Physics 2014-09-29 R. Steinigeweg , F. Heidrich-Meisner , J. Gemmer , K. Michielsen , H. De Raedt

We study the Arnold diffusion in a priori unstable near-integrable systems in a neighbourhood of a resonance of low order. We consider a non-autonomous near-integrable Hamiltonian system with $n+1/2$ degrees of freedom, $n\ge 2$. Let the…

Dynamical Systems · Mathematics 2018-07-23 Mars Davletshin , Dmitry Treschev

The short--time self diffusion coefficient of a sphere in a suspension of rigid rods is calculated in first order in the rod volume fraction. For low rod concentrations the correction to the Einstein diffusion constant of the sphere is a…

Soft Condensed Matter · Physics 2008-12-03 J. Guzowski , B. Cichocki , E. Wajnryb , G. C. Abade

We formulate a scaling theory for the long-time diffusive motion in a space occluded by a high density of moving obstacles in dimensions 1, 2 and 3. Our tracers diffuse anomalously over many decades in time, before reaching a diffusive…

Statistical Mechanics · Physics 2024-10-22 H. Bendekgey , G. Huber , D. Yllanes

The non-crossing approximation (NCA) is generalized for the Anderson model with finite Coulomb repulsion U. Resummation of infinite number of terms is performed so as to incorporate all leading contributions in the limit of large degeneracy…

Strongly Correlated Electrons · Physics 2007-05-23 J. Otsuki , Y. Kuramoto

We find that Anderson localization ceases to exist when a random medium begins to move, but another type of fundamental quantum effect, Planckian diffusion $D = \alpha\hbar/m$, rises to replace it, with $\alpha $ of order of unity.…

Quantum Physics · Physics 2024-12-02 Yubo Zhang , Anton M. Graf , Alhun Aydin , Joonas Keski-Rahkonen , Eric J. Heller

We study a class of reflected McKean-Vlasov diffusions over a convex domain with self-stabilizing coefficients. This includes coefficients that do not satisfy the classical Wasserstein Lipschitz condition. Further, the process is…

Probability · Mathematics 2022-01-19 Daniel Adams , Gonçalo dos Reis , Romain Ravaille , William Salkeld , Julian Tugaut

We studied the self-diffusion of colloidal ellipsoids in a monolayer near a flat wall by video microscopy. The image processing algorithm can track the positions and orientations of ellipsoids with sub-pixel resolution. The translational…

Soft Condensed Matter · Physics 2015-05-19 Zhongyu Zheng , Yilong Han

Score-based diffusion models have demonstrated outstanding empirical performance in machine learning and artificial intelligence, particularly in generating high-quality new samples from complex probability distributions. Improving the…

Machine Learning · Statistics 2025-05-30 Yuchen Jiao , Gen Li

The aforementioned celebrated model, though a breakthrough in Stochastic processes and a great step toward the construction of the Brownian motion leads to a paradox: infinite propagation speed and violation of the 2nd law of…

Analysis of PDEs · Mathematics 2022-09-13 Isanka Garli Hevage , Akif Ibragimov , Zeev Sobol

We consider the increase of the spatial variance of some inhomogeneous, non-equilibrium density (particles, energy, etc.) in a periodic quantum system of condensed matter-type. This is done for a certain class of initial quantum states…

Statistical Mechanics · Physics 2009-10-23 Robin Steinigeweg , Hannu Wichterich , Jochen Gemmer

We present an analytical closed form expression, which gives a good approximate propagator for diffusion on the sphere. Our formula is the spherical counterpart of the Gaussian propagator for diffusion on the plane. While the analytical…

Statistical Mechanics · Physics 2016-10-05 Abhijit Ghosh , Joseph Samuel , Supurna Sinha

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