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Survival analysis aims to estimate a time-to-event distribution from data with censored observations. Many existing methods either impose structural assumptions on the hazard function or discretize the time axis, which may limit flexibility…

Machine Learning · Computer Science 2026-05-22 Stanislav R. Kirpichenko , Andrei V. Konstantinov , Lev V. Utkin

In this work, we explore a time-fractional diffusion equation of order $\alpha \in (0,1)$ with a stochastic diffusivity parameter. We focus on efficient estimation of the expected values (considered as an infinite dimensional integral on…

Numerical Analysis · Mathematics 2024-09-04 Josef Dick , Hecong Gao , William McLean , Kassem Mustapha

Predicting species persistence within ecological communities is a fundamental challenge for both empirical and theoretical ecology. Existing methods span from mechanistic models, whose parameters are difficult to estimate from data, to…

Populations and Evolution · Quantitative Biology 2026-04-30 Davide Bernardi , Giorgio Nicoletti , Prajwal Padmanabha , Samir Suweis , Sandro Azaele , Simon A. Levin , Andrea Rinaldo , Amos Maritan

We study an initial-boundary value problem of variable-order time-fractional diffusion equations in one space dimension. Based on the wellposedness of the proposed model and the smoothing properties of its solutions, which are shown to be…

Analysis of PDEs · Mathematics 2020-01-08 Xiangcheng Zheng , Jin Cheng , Hong Wang

Animals use various processes to inform themselves about their environment and make decisions about how to move and form their territory. In some cases, populations inform themselves of competing groups through observations at distances,…

Populations and Evolution · Quantitative Biology 2022-11-17 Erin Ellefsen , Nancy Rodriguez

Systems of reaction-diffusion equations are commonly used in biological models of food chains. The populations and their complicated interactions present numerous challenges in theory and in numerical approximation. In particular,…

Numerical Analysis · Mathematics 2015-10-28 Matthew Beauregard , Joshua Padgett , Rana Parshad

This paper is devoted to the study of propagation dynamics for a large class of non-monotone evolution systems. In two directions of the spatial variable, such a system has two limiting systems admitting the spatial translation invariance.…

Dynamical Systems · Mathematics 2023-10-23 Taishan Yi , Xiao-Qiang Zhao

This is the first of two papers where we discuss the limits imposed by competition to the biodiversity of species communities. In this first paper we study the coexistence of competing species at the fixed point of population dynamic…

Populations and Evolution · Quantitative Biology 2007-05-23 Ugo Bastolla , Michael Lässig , Susanna C. Manrubia , Angelo Valleriani

Diffusion models have recently emerged as powerful learners for simulation-based inference (SBI), enabling fast and accurate estimation of latent parameters from simulated and real data. Their score-based formulation offers a flexible way…

Machine Learning · Statistics 2026-01-30 Jonas Arruda , Niels Bracher , Ullrich Köthe , Jan Hasenauer , Stefan T. Radev

We investigate the super-linear spreading in a reaction-diffusion model analogous to the Fisher-KPP equation, but in which the population is heterogeneous with respect to the dispersal ability of individuals, and the saturation factor is…

Analysis of PDEs · Mathematics 2019-10-15 Vincent Calvez , Christopher Henderson , Sepideh Mirrahimi , Olga Turanova , Thierry Dumont

We present properties of Lotka-Volterra equations describing ecological competition among a large number of competing species. First we extend to the case of a non-homogeneous niche space stability conditions for solutions representing…

Populations and Evolution · Quantitative Biology 2009-07-22 Emilio Hernandez-Garcia , Cristobal Lopez , Simone Pigolotti , Ken H. Andersen

Spatially extended population dynamics models that incorporate intrinsic noise serve as case studies for the role of fluctuations and correlations in biological systems. Including spatial structure and stochastic noise in predator-prey…

Statistical Mechanics · Physics 2018-01-09 Ulrich Dobramysl , Mauro Mobilia , Michel Pleimling , Uwe C. Täuber

We are concerned with the persistence of both predator and prey in a diffusive predator-prey system with a climate change effect, which is modeled by a spatial-temporal heterogeneity depending on a moving variable. Moreover, we consider…

Analysis of PDEs · Mathematics 2021-05-10 Wonhyung Choi , Thomas Giletti , Jong-Shenq Guo

Ecosystems display a complex spatial organization. Ecologists have long tried to characterize them by looking at how different measures of biodiversity change across spatial scales. Ecological neutral theory has provided simple predictions…

Populations and Evolution · Quantitative Biology 2017-12-13 Simone Pigolotti , Massimo Cencini , Daniel Molina , Miguel A. Muñoz

The Fisher-KPP partial differential equation has been employed in science to model various biological, chemical, and thermal phenomena. Time fractional extensions of Fisher's equation have also appeared in the literature, aiming to model…

Numerical Analysis · Mathematics 2025-08-25 Theodore V. Gortsas

The main objective of this paper is analysis of the initial-boundary value problems for the linear time-fractional diffusion equations with a uniformly elliptic spatial differential operator of the second order and the Caputo type…

Analysis of PDEs · Mathematics 2023-04-18 Yuri Luchko , Masahiro Yamamoto

We investigate the problem of speciation and coexistence in simple ecosystems when the competition among individuals is included in the Eigen model for quasi-species. By suggesting an analogy between the competition among strains and the…

Statistical Mechanics · Physics 2008-02-03 Franco Bagnoli , Michele Bezzi

We present new theoretical and empirical results on the probability distributions of species persistence times in natural ecosystems. Persistence times, defined as the timespans occurring between species' colonization and local extinction…

Populations and Evolution · Quantitative Biology 2012-03-21 S. Suweis , E. Bertuzzo , L. Mari , I. Rodriguez-Iturbe , A. Maritan , A. Rinaldo

This paper investigates the large time behaviour of a three species reaction-diffusion system, modelling the spatial invasion of two predators feeding on a single prey species. In addition to the competition for food, the two predators…

Analysis of PDEs · Mathematics 2020-07-07 Arnaud Ducrot , Thomas Giletti , Jong-Shenq Guo , Masahiko Shimojo

By considering the master equation of asymmetric exclusion process on a one-dimensional lattice, we obtain the most general boundary condition of the multi-species exclusion processes in which the number of particles is constant in time.…

Statistical Mechanics · Physics 2009-11-10 Masoud Alimohammadi