New Insights into Population Dynamics from the Continuous McKendrick Model

Fuente: arXiv
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Auteur principal: Covei, Dragos-Patru
Format: Preprint
Publié: 2025
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author Covei, Dragos-Patru
author_facet Covei, Dragos-Patru
contents This article presents a comprehensive study of the continuous McKendrick model, which serves as a foundational framework in population dynamics and epidemiology. The model is formulated through partial differential equations that describe the temporal evolution of the age distribution of a population using continuously defined birth and death rates. In this work, we provide rigorous derivations of the renewal equation, establish the appropriate boundary conditions, and perform a detailed analysis of the survival functions. The central result demonstrates that the population approaches extinction if and only if the net reproduction number $R_{n}$ is strictly less than unity. We present two independent proofs: one based on Laplace transform techniques and Tauberian theorems, and another employing a reformulation as a system of ordinary differential equations with eigenvalue analysis. Additionally, we establish the connection between the deterministic framework and stochastic process formulations, showing that the McKendrick equation emerges as the fluid limit of an individual-based stochastic model.
format Preprint
id arxiv_https___arxiv_org_abs_2504_21103
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle New Insights into Population Dynamics from the Continuous McKendrick Model
Covei, Dragos-Patru
Populations and Evolution
Dynamical Systems
35Q92, 35F16, 92D25, 45D05
This article presents a comprehensive study of the continuous McKendrick model, which serves as a foundational framework in population dynamics and epidemiology. The model is formulated through partial differential equations that describe the temporal evolution of the age distribution of a population using continuously defined birth and death rates. In this work, we provide rigorous derivations of the renewal equation, establish the appropriate boundary conditions, and perform a detailed analysis of the survival functions. The central result demonstrates that the population approaches extinction if and only if the net reproduction number $R_{n}$ is strictly less than unity. We present two independent proofs: one based on Laplace transform techniques and Tauberian theorems, and another employing a reformulation as a system of ordinary differential equations with eigenvalue analysis. Additionally, we establish the connection between the deterministic framework and stochastic process formulations, showing that the McKendrick equation emerges as the fluid limit of an individual-based stochastic model.
title New Insights into Population Dynamics from the Continuous McKendrick Model
topic Populations and Evolution
Dynamical Systems
35Q92, 35F16, 92D25, 45D05
url https://arxiv.org/abs/2504.21103