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A {\em propagation-dispersion equation} is derived for the first passage distribution function of a particle moving on a substrate with time delays. The equation is obtained as the continuous limit of the {\em first visit equation}, an…

Statistical Mechanics · Physics 2007-05-23 Jean Pierre Boon , Patrick Grosfils , James F. Lutsko

This paper is concerned with the asymptotic behavior of the generalized principal eigenvalues of elliptic operators and spreading speeds of Fisher-KPP equations in two-scale almost periodic media where one scale is fixed and another one…

Analysis of PDEs · Mathematics 2025-12-04 Xing Liang , Linfeng Xu , Tao Zhou

Our investigation focuses on the asymptotic spreading behavior of the Fisher-KPP equation with a mixed local-nonlocal operator in the diffusion (see the work by X. Cabr\'e and J.-M. Roquejoffre, 2013, ref.[8]) to the setting of mixed…

Analysis of PDEs · Mathematics 2025-09-01 Begoña Barrios , Bryan Pichucho , Alexander Quaas

We study a Fisher-KPP equation with spatially periodic diffusion and reaction terms. We identify a class of periodic media for which the equation admits an explicit, closed-form solution. Through a nonlinear change of variables, the problem…

Analysis of PDEs · Mathematics 2025-12-09 Lionel Roques

In this paper we focus on three problems about the spreading speeds of nonlocal dispersal Fisher-KPP equations. First, we study the signs of spreading speeds and find that they are determined by the asymmetry level of the nonlocal dispersal…

Analysis of PDEs · Mathematics 2020-07-31 Wen-Bing Xu , Wan-Tong Li , Shigui Ruan

In this paper, we show that all non-trivial solutions of a broad class of nonlinear dispersive equations, whose linear evolution is governed by a dispersion relation under minimal regularity assumptions, cannot remain compactly supported…

Analysis of PDEs · Mathematics 2026-02-23 Brian Choi , Steven Walton

We consider the wave propagation for a reaction-diffusion equation on the real line, with a random drift and Fisher-Kolmogorov-Petrovskii-Piscounov (FKPP) type nonlinear reaction. We show that when the average drift is positive, the…

Analysis of PDEs · Mathematics 2026-01-27 Dihang Guan , Hui He , Wenqing Hu , Jiaojiao Yang

This paper is devoted to the study of some qualitative and quantitative aspects of nonlinear propagation phenomena in diffusive media. More precisely, we consider the case a reaction-diffusion equation in a periodic medium with…

Analysis of PDEs · Mathematics 2009-04-27 Francois Hamel , Yannick Sire

In this paper, we treat the Fisher-KPP equation with a Caputo-type time fractional derivative and discuss the propagation speed of the solution. The equation is a mathematical model that describes the processes of sub-diffusion,…

Analysis of PDEs · Mathematics 2026-01-21 Hiroshi Ishii

In this paper, we study the diffusion approximation for singularly perturbed stochastic reaction-diffusion equation with a fast oscillating term. The asymptotic limit for the original system is obtained, where an extra Gaussian term…

Probability · Mathematics 2021-06-08 Longjie Xie , Li Yang

This paper is concerned with the large-time dynamics of bounded solutions of reaction-diffusion equations with bounded or unbounded initial support in R N. We start with a survey of some old and recent results on the spreading speeds of the…

Analysis of PDEs · Mathematics 2024-07-02 François Hamel , Luca Rossi

We provide an asymptotic analysis of a fractional Fisher-KPP type equation in periodic non-connected 1-dimensional media with Dirichlet conditions outside the domain. After demonstrating the existence and uniqueness of a non-trivial bounded…

Analysis of PDEs · Mathematics 2019-10-28 Alexis Léculier , Sepideh Mirrahimi , Jean-Michel Roquejoffre

We study the velocity of travelling waves of a reaction-diffusion system coupling a standard reaction-diffusion equation in a strip with a one-dimensional diffusion equation on a line. We show that it grows like the square root of the…

Analysis of PDEs · Mathematics 2015-07-02 Laurent Dietrich

The famous Fisher-KPP reaction-diffusion model combines linear diffusion with the typical KPP reaction term, and appears in a number of relevant applications in biology and chemistry. It is remarkable as a mathematical model since it…

Analysis of PDEs · Mathematics 2016-02-19 Alessandro Audrito , Juan Luis Vázquez

We develop perturbative expansions to obtain solutions for the initial-value problems of two important reaction-diffusion systems, viz., the Fisher equation and the time-dependent Ginzburg-Landau (TDGL) equation. The starting point of our…

Condensed Matter · Physics 2009-11-07 Sanjay Puri , Kay Joerg Wiese

We consider a reaction-diffusion equation in narrow random channels. We approximate the generalized solution to this equation by the corresponding one on a random graph. By making use of large deviation analysis we study the asymptotic wave…

Probability · Mathematics 2013-07-15 Mark Freidlin , Wenqing Hu

We solve a physically significant extension of a classic problem in the theory of diffusion, namely the Ornstein-Uhlenbeck process [G. E. Ornstein and L. S. Uhlenbeck, Phys. Rev. 36, 823, (1930)]. Our generalised Ornstein-Uhlenbeck systems…

Statistical Mechanics · Physics 2009-11-11 V. Bezuglyy , B. Mehlig , M. Wilkinson , K. Nakamura , E. Arvedson

The problem of diffusion in a time-dependent (and generally inhomogeneous) external field is considered on the basis of a generalized master equation with two times, introduced in [1,2]. We consider the case of the quasi Fokker-Planck…

Statistical Mechanics · Physics 2015-05-18 S. A. Trigger , G. J. F. van Heijst , O. F. Petrov , P. P. J. M. Schram

Spreading of bacteria in a highly advective, disordered environment is examined. Predictions of super-diffusive spreading for a simplified reaction-diffusion equation are tested. Concentration profiles display anomalous growth and…

Biological Physics · Physics 2007-05-23 John H. Carpenter , Karin A. Dahmen

The Fisher-KPP equation is a reaction-diffusion equation originally proposed by Fisher to represent allele propagation in genetic hosts or population. It was also proposed by Kolmogorov for more general applications. A novel method for…

Mathematical Physics · Physics 2021-08-25 Luisiana Cundin