Discrete or distributed delay? Effects on stability of population growth

The growth of a population subject to maturation delay is modeled by using either a discrete delay or a delay continuously distributed over the population. The occurrence of stability switches (stable-unstable-stable) of the positive equilibrium as the delay increases is investigated in both cases....

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Main Authors: Edoardo Beretta, Dimitri Breda
Format: Article
Language:English
Published: AIMS Press 2015-09-01
Series:Mathematical Biosciences and Engineering
Subjects:
Online Access:https://www.aimspress.com/article/doi/10.3934/mbe.2016.13.19
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author Edoardo Beretta
Dimitri Breda
author_facet Edoardo Beretta
Dimitri Breda
author_sort Edoardo Beretta
collection DOAJ
description The growth of a population subject to maturation delay is modeled by using either a discrete delay or a delay continuously distributed over the population. The occurrence of stability switches (stable-unstable-stable) of the positive equilibrium as the delay increases is investigated in both cases. Necessary and sufficient conditions are provided by analyzing the relevant characteristic equations. It is shown that for any choice of parameter values for which the discrete delay model presents stability switches there exists a maximum delay variance beyond which no switch occurs for the continuous delay model: the delay variance has a stabilizing effect. Moreover, it is illustrated how, in the presence of switches, the unstable delay domain is as larger as lower is the ratio between the juveniles and the adults mortality rates.
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spelling doaj-art-7939df492ed64a86b6cc6b752a302c0f2025-01-24T02:34:05ZengAIMS PressMathematical Biosciences and Engineering1551-00182015-09-01131194110.3934/mbe.2016.13.19Discrete or distributed delay? Effects on stability of population growthEdoardo Beretta0Dimitri Breda1CIMAB, University of Milano, via C. Saldini 50, I20133 MilanoDepartment of Mathematics and Computer Science, University of Udine, via delle Scienze 206, I33100 UdineThe growth of a population subject to maturation delay is modeled by using either a discrete delay or a delay continuously distributed over the population. The occurrence of stability switches (stable-unstable-stable) of the positive equilibrium as the delay increases is investigated in both cases. Necessary and sufficient conditions are provided by analyzing the relevant characteristic equations. It is shown that for any choice of parameter values for which the discrete delay model presents stability switches there exists a maximum delay variance beyond which no switch occurs for the continuous delay model: the delay variance has a stabilizing effect. Moreover, it is illustrated how, in the presence of switches, the unstable delay domain is as larger as lower is the ratio between the juveniles and the adults mortality rates.https://www.aimspress.com/article/doi/10.3934/mbe.2016.13.19stability switches.$\delta$-dirac distributiongamma distributionpopulation growthlocal asymptotic stability analysismaturation delay
spellingShingle Edoardo Beretta
Dimitri Breda
Discrete or distributed delay? Effects on stability of population growth
Mathematical Biosciences and Engineering
stability switches.
$\delta$-dirac distribution
gamma distribution
population growth
local asymptotic stability analysis
maturation delay
title Discrete or distributed delay? Effects on stability of population growth
title_full Discrete or distributed delay? Effects on stability of population growth
title_fullStr Discrete or distributed delay? Effects on stability of population growth
title_full_unstemmed Discrete or distributed delay? Effects on stability of population growth
title_short Discrete or distributed delay? Effects on stability of population growth
title_sort discrete or distributed delay effects on stability of population growth
topic stability switches.
$\delta$-dirac distribution
gamma distribution
population growth
local asymptotic stability analysis
maturation delay
url https://www.aimspress.com/article/doi/10.3934/mbe.2016.13.19
work_keys_str_mv AT edoardoberetta discreteordistributeddelayeffectsonstabilityofpopulationgrowth
AT dimitribreda discreteordistributeddelayeffectsonstabilityofpopulationgrowth