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We study the Brownian motion of a classical particle in one-dimensional inhomogeneous environments where the transition probabilities follow quasiperiodic or aperiodic distributions. Exploiting an exact correspondence with the…

Statistical Mechanics · Physics 2009-10-31 F. Igloi , L. Turban , H. Rieger

Diffusive motion is a fundamental transport mechanism in physical and biological systems, governing dynamics across a wide range of scales -- from molecular transport to animal foraging. In many complex systems, however, diffusion deviates…

Statistical Mechanics · Physics 2026-05-01 Takuma Akimoto , Jae-Hyung Jeon , Ralf Metzler , Tomoshige Miyaguchi , Takashi Uneyama , Eiji Yamamoto

The non-Gaussian normal diffusion, i.e., the probability distribution function (PDF) is non-Gaussian but the mean squared displacement (MSD) depends on time linearly, has been observed in particle motions. Here we show by numerical…

Disordered Systems and Neural Networks · Physics 2016-04-06 Jianjin Wang , Yong Zhang , Hong Zhao

Representing the nodes of continuous-time temporal graphs in a low-dimensional latent space has wide-ranging applications, from prediction to visualization. Yet, analyzing continuous-time relational data with timestamped interactions…

Machine Learning · Computer Science 2024-05-28 Raphaël Romero , Jefrey Lijffijt , Riccardo Rastelli , Marco Corneli , Tijl De Bie

Accurate forecasting of spatiotemporal data remains challenging due to complex spatial dependencies and temporal dynamics. The inherent uncertainty and variability in such data often render deterministic models insufficient, prompting a…

Machine Learning · Computer Science 2024-11-05 Mingze Gong , Lei Chen , Jia Li

Diffusion-based generative models use stochastic differential equations (SDEs) and their equivalent ordinary differential equations (ODEs) to establish a smooth connection between a complex data distribution and a tractable prior…

Machine Learning · Computer Science 2024-08-25 Defang Chen , Zhenyu Zhou , Can Wang , Chunhua Shen , Siwei Lyu

Random geometric graphs (RGG) can be formalized as hidden-variables models where the hidden variables are the coordinates of the nodes. Here we develop a general approach to extract the typical configurations of a generic hidden-variables…

Disordered Systems and Neural Networks · Physics 2015-04-28 Massimo Ostilli , Ginestra Bianconi

We propose a generalized diffusion equation for a flat Euclidean space subjected to a continuous infinitesimal scale transform. For the special cases of an algebraic or exponential expansion/contraction, governed by time-dependent scale…

Statistical Mechanics · Physics 2018-04-17 Manuel Schrauth , Maximilian Schneider

The presence of global conserved quantities in interacting systems generically leads to diffusive transport at late times. Here, we show that systems conserving the dipole moment of an associated global charge, or even higher moment…

Strongly Correlated Electrons · Physics 2020-12-22 Johannes Feldmeier , Pablo Sala , Giuseppe de Tomasi , Frank Pollmann , Michael Knap

Spatial reaction-diffusion models have been employed to describe many emergent phenomena in biological systems. The modelling technique most commonly adopted in the literature implements systems of partial differential equations (PDEs),…

Quantitative Methods · Quantitative Biology 2015-10-05 Christian A. Yates , Mark B. Flegg

Motivated by experimental progress in strongly coupled atom-photon systems in optical cavities, we study theoretically the quantum dynamics of atoms coupled to a one-dimensional dynamical optical lattice. The dynamical lattice is chosen to…

Quantum Gases · Physics 2018-02-14 Wei Zheng , Nigel R. Cooper

Uchaikin suggested a mathematical model of an anomalous diffusion in a space was suggested. This model origins in an investigation of processes in complex systems with variable structure: glasses, liquid crystals, biopolymers, proteins and…

Probability · Mathematics 2007-05-23 G. Sh. Tsitsiashvili , A. E. Yashin

We address the problem of the statistical analysis of a time series generated by complex dynamics with a new method: the Diffusion Entropy Analysis (DEA) (Fractals, {\bf 9}, 193 (2001)). This method is based on the evaluation of the Shannon…

Statistical Mechanics · Physics 2016-08-31 Nicola Scafetta , Vito Latora , Paolo Grigolini

In a recent paper, Michael J. Saxton proposes to interpret as anomalous diffusion the occurrence of apparent transient sub-diffusive regimes in mean-squared displacements (MSD) plots, calculated from experimental trajectories of molecules…

Subcellular Processes · Quantitative Biology 2009-11-13 Nicolas Destainville , Aude Sauliere , Laurence Salome

The forward model in diffuse optical tomography (DOT) describes how light propagates through a turbid medium. It is often approximated by a diffusion equation (DE) that is numerically discretized by the classical finite element method…

Computational Physics · Physics 2019-06-04 Wenqi Lu , Jinming Duan , Joshua Deepak Veesa , Iain B. Styles

We present a concise, self-contained derivation of diffusion-based generative models. Starting from basic properties of Gaussian distributions (densities, quadratic expectations, re-parameterisation, products, and KL divergences), we…

Machine Learning · Computer Science 2025-11-18 Sepehr Maleki , Negar Pourmoazemi

There is a class of problems that exhibit smooth behavior on macroscopic scales, where only a microscopic evolution law is known. Patch dynamics scheme of `equation-free multiscale modelling' is one of the techniques, which aims to extract…

Numerical Analysis · Mathematics 2024-01-17 T. K. Karmakar , D. C. Dalal

This paper uses dynamical invariants to describe the evolution of collisionless systems subject to time-dependent gravitational forces without resorting to maximum-entropy probabilities. We show that collisionless relaxation can be viewed…

Astrophysics of Galaxies · Physics 2015-06-03 Jorge Peñarrubia

Diffusion models have recently emerged as powerful stochastic frameworks for high-dimensional inference and generation. However, existing applications to partial differential equations (PDEs) predominantly rely on physics-informed training…

Numerical Analysis · Mathematics 2026-04-03 Yi Bing , Liu Jia , Fu Jinyang , Peng Xiang

We study the relaxation process in normal and anomalous diffusion regimes for systems described by a generalized Langevin equation (GLE). We demonstrate the existence of a very general correlation function which describes the relaxation…

Disordered Systems and Neural Networks · Physics 2007-05-23 Mendeli H. Vainstein , Ismael V. L. Costa , Rafael Morgado , Fernando A. Oliveira