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Diffusion probabilistic models excel at sampling new images from learned distributions. Originally motivated by drift-diffusion concepts from physics, they apply image perturbations such as noise and blur in a forward process that results…

Image and Video Processing · Electrical Eng. & Systems 2024-06-07 Pascal Peter

One century after Einstein's work, Brownian Motion still remains both a fundamental open issue and a continous source of inspiration for many areas of natural sciences. We first present a discussion about stochastic and deterministic…

Chaotic Dynamics · Physics 2009-11-10 Fabio Cecconi , Massimo Cencini , Massimo Falcioni , Angelo Vulpiani

Anomalous diffusion is discussed in the context of quantum Brownian motion with colored noise. It is shown that earlier results follow simply and directly from the fluctuation-dissipation theorem. The limits on the long-time dependence of…

Quantum Physics · Physics 2007-05-23 G. W. Ford , R. F. O'Connell

The reflection and transmission amplitudes of waves in disordered multimode waveguides are studied by means of numerical simulations based on the invariant embedding equations. In particular, we analyze the influence of surface-type…

Disordered Systems and Neural Networks · Physics 2009-10-31 J. A. Sanchez-Gil , V. Freilikher , A. A. Maradudin , I. Yurkevich

We show that when Brownian motion takes place in a heterogeneous medium, the presence of local forces and transport coefficients leads to deviations from a Gaussian probability distribution that make that the ratio between forward and…

Soft Condensed Matter · Physics 2016-12-21 Paolo Malgaretti , Ignacio Pagonabarraga Miguel J. Rubi

Light propagation in an infinite uniform turbid medium is treated as a Markov stochastic process of photons to provide an intuitive framework for photon migration. The macroscopic physical quantities of photon migration are shown to be…

Disordered Systems and Neural Networks · Physics 2007-05-23 M. Xu , W. Cai , M. Lax , R. R. Alfano

Diffusion processes in networks are increasingly used to model the spread of information and social influence. In several applications in computational sustainability such as the spread of wildlife, infectious diseases and traffic mobility…

Social and Information Networks · Computer Science 2013-09-27 Akshat Kumar , Daniel Sheldon , Biplav Srivastava

Diffusion models are loosely modelled based on non-equilibrium thermodynamics, where \textit{diffusion} refers to particles flowing from high-concentration regions towards low-concentration regions. In statistics, the meaning is quite…

Machine Learning · Computer Science 2023-12-19 Inga Strümke , Helge Langseth

No surface is perfectly planar at all scales. The notion of flatness of a surface therefore depends on the size of the probe used to observe it. As a consequence rough interfaces are abundant in nature. Here the old, but still active field…

Statistical Mechanics · Physics 2007-05-23 Ingve Simonsen

The diffusion of a pulse of small grains in an horizontal rotating drum is studied through discrete elements methods simulations. We present a theoretical analysis of the diffusion process in a one-dimensional confined space in order to…

Other Condensed Matter · Physics 2007-05-23 Nicolas Taberlet , Patrick Richard

The dispersion of a diffusive scalar in a fluid flowing through a network has many applications including to biological flows, porous media, water supply and urban pollution. Motivated by this, we develop a large-deviation theory that…

Fluid Dynamics · Physics 2016-09-14 Alexandra Tzella , Jacques Vanneste

The transformation from evanescent waves to propagation waves is the key mechanism for the realization of some super-resolution imaging methods. By using the recursive Green function and scattering-matrix theory, we investigated in details…

Mesoscale and Nanoscale Physics · Physics 2017-09-12 Dequan Zhang , Yuchen Xu , Ke Xu , Hao Zhang , Jing Li , Heyuan Zhu , Costas Soukoulis

Based on a coarse-grained model, we carry out molecular dynamics simulations to analyze the diffusion of a small tracer particle inside a cylindrical channel whose inner wall is covered with randomly grafted short polymeric chains. We…

Soft Condensed Matter · Physics 2013-06-20 Rajarshi Chakrabarti , Stefan Kesselheim , Peter Kosovan , Christian Holm

Scattering through natural porous formations (by far the most ubiquitous example of disordered media) represents a formidable tool to identify effective flow and transport properties. In particular, we are interested here in the scattering…

Soft Condensed Matter · Physics 2023-05-16 Gerardo Severino , Francesco Giannino

We introduce a location statistic for distributions on non-linear geometric spaces, the diffusion mean, serving as an extension and an alternative to the Fr\'echet mean. The diffusion mean arises as the generalization of Gaussian maximum…

Statistics Theory · Mathematics 2022-12-06 Benjamin Eltzner , Pernille Hansen , Stephan F. Huckemann , Stefan Sommer

Thermal diffusion has been studied for over 150 years. Despite of the long history and the increasing importance of the phenomenon, the physics of thermal diffusion remains poorly understood. In this paper Ludwig's thermal diffusion is…

Mathematical Physics · Physics 2013-07-18 Yong-Jung Kim

The theory of nonlinear diffraction of intensive light beams propagating through photorefractive media is developed. Diffraction occurs on a reflecting wire embedded in the nonlinear medium at relatively small angle with respect to the…

Pattern Formation and Solitons · Physics 2009-11-13 E. G. Khamis , A. Gammal , G. A. El , Yu. G. Gladush , A. M. Kamchatnov

The paradigmatic model for heterogeneous media used in diffusion studies is built from reflecting obstacles and surfaces. It is well known that the crowding effect produced by these reflecting surfaces slows the dispersion of Brownian…

Statistical Mechanics · Physics 2022-06-08 Arthur Alexandre , Matthieu Mangeat , Thomas Guérin , David S. Dean

An electromagnetic wave-packet propagating in a linear, homogeneous, and isotropic medium changes shape while its envelope travels with different velocities at different points in spacetime. In general, a wave-packet can be described as a…

Optics · Physics 2020-08-26 Masud Mansuripur

In the paper, we discuss the studies of mathematical models of diffusion scattering of waves in the phase space, and relation of these models with quantum mechanics. In the previous works it is shown that in these models of classical…

Mathematical Physics · Physics 2016-03-22 E. M. Beniaminov