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Darwinian evolution can be modeled in general terms as a flow in the space of fitness (i.e. reproductive rate) distributions. In the diffusion approximation, Tsimring et al. have showed that this flow admits "fitness wave" solutions:…

Populations and Evolution · Quantitative Biology 2017-01-30 Matteo Smerlak , Ahmed Youssef

By generalizing a class of models recently introduced to account for protracted transients in biological systems, we identify a novel mechanism for hyperuniformity. In this model, competition of particles over a shared resource guides the…

Statistical Mechanics · Physics 2025-12-11 Tal Agranov , Natan Wiegenfeld , Omer Karin , Benjamin D. Simons

The nonlocal Fisher equation is a diffusion-reaction equation with a nonlocal quadratic competition, which describes the reaction between distant individuals. This equation arises in evolutionary biological systems, where the arena for the…

Pattern Formation and Solitons · Physics 2018-04-25 Yehuda A. Ganan , David A. Kessler

Diffusion models have recently exhibited remarkable abilities to synthesize striking image samples since the introduction of denoising diffusion probabilistic models (DDPMs). Their key idea is to disrupt images into noise through a fixed…

Computer Vision and Pattern Recognition · Computer Science 2023-03-28 Zijian Zhang , Zhou Zhao , Jun Yu , Qi Tian

Diffusion is a fundamental phenomenon that occurs ubiquitously in nature and remains the subject of continuous research interest. Understanding diffusion is a key to understanding leaving systems. In this Chapter, I discuss diffusion of…

Soft Condensed Matter · Physics 2018-10-15 Svyatoslav Kondrat

We propose a mathematical model, namely a reaction-diffusion system, to describe social behaviour of cockroaches. An essential new aspect in our model is that the dispersion behaviour due to overcrowding effect is taken into account {as a…

Analysis of PDEs · Mathematics 2021-11-16 Jan Elias , Hirofumi Izuhara , Masayasu Mimura , Bao Quoc Tang

In various situations where wave transport is preeminent, like in wireless communication, a strong established transmission is present in a complex scattering environment. We develop a novel approach to describe emerging fluctuations, which…

Mesoscale and Nanoscale Physics · Physics 2020-10-08 Dmitry V. Savin , Martin Richter , Ulrich Kuhl , Olivier Legrand , Fabrice Mortessagne

We develop a straightforward analytical framework for the propagation of spatial light modes through a turbulent atmosphere. Built upon the split-step approach with the mode-based optical field representation, it directly assesses how…

Quantum Physics · Physics 2026-05-29 Konstantin Kravtsov

Living entities in a group communicate and transfer information to one another for a variety of reasons. It might be for foraging food, migration, or escaping threats and obstacles, etc. They do so by interacting with each other and also…

Biological Physics · Physics 2024-04-03 Md. Samsuzzaman , Mohammad Hasanuzzaman , Ahmed Sayeed , Arnab Saha

Railway systems form an important means of transport across the world. However, congestions or disruptions may significantly decrease these systems' efficiencies, making predicting and understanding the resulting train delays a priority for…

Physics and Society · Physics 2021-05-14 Mark M. Dekker , Alexey N. Medvedev , Jan Rombouts , Grzegorz Siudem , Liubov Tupikina

A one-dimensional rule-based model for flocking, that combines velocity alignment and long-range centering interactions, is presented and studied. The induced cohesion in the collective motion of the self-propelled agents leads to a unique…

Statistical Mechanics · Physics 2015-01-19 V. Dossetti

We investigate front propagation in a reacting particle system in which particles perform scale-free random walks known as Levy flights. The system is described by a fractional generalization of a reaction-diffusion equation. We focus on…

Statistical Mechanics · Physics 2007-05-23 D. Brockmann , L. Hufnagel

We present a simple model of protesters scattered throughout a city who want to gather into large and mobile groups. This model relies on random walkers on a street network that follow tactics built from a set of basic rules. Our goal is to…

Multiagent Systems · Computer Science 2025-12-16 Guillaume Moinard , Matthieu Latapy

We study competition between two biological species advected by a compressible velocity field. Individuals are treated as discrete Lagrangian particles that reproduce or die in a density-dependent fashion. In the absence of a velocity field…

Populations and Evolution · Quantitative Biology 2012-04-24 Simone Pigolotti , Roberto Benzi , Mogens H. Jensen , David R. Nelson

We simulate the granular flow in a narrow pipe with a lattice-gas automaton model. We find that the density in the system is characterized by two features. One is that spontaneous density waves propagate through the system with well-defined…

Condensed Matter · Physics 2009-10-22 Gongwen Peng , Hans J. Herrmann

We investigate the influence of a shifting environment on the spreading of an invasive species through a model given by the diffusive logistic equation with a free boundary. When the environment is homogeneous and favourable, this model was…

Analysis of PDEs · Mathematics 2015-08-27 Yihong Du , Lei Wei , Ling Zhou

We study the persistence and propagation (or blocking) phenomena for a species in periodically hostile environments. The problem is described by a reaction-diffusion equation with zero Dirichlet boundary condition. We first derive the…

Analysis of PDEs · Mathematics 2015-05-28 Jong-Shenq Guo , Francois Hamel

We investigate the propagation of scalar waves induced by matter sources in the context of scalar-tensor theories of gravity which include screening mechanisms for the scalar degree of freedom. The usual approach when studying these…

General Relativity and Quantum Cosmology · Physics 2016-02-24 Jan Ø. Lindroos , Claudio Llinares , David F. Mota

Recently it has been shown that when an equation that allows so-called pulled fronts in the mean-field limit is modelled with a stochastic model with a finite number $N$ of particles per correlation volume, the convergence to the speed…

Statistical Mechanics · Physics 2009-11-07 Debabrata Panja

The effect of advection on the critical minimal speed of traveling waves is studied. Previous theoretical studies estimated the effect on the velocity of stable fast waves and predicted the existence of a critical advection strength below…

Pattern Formation and Solitons · Physics 2014-04-24 Frederike Kneer , Klaus Obermayer , Markus A. Dahlem