A many-body field theory approach to stochastic models in population biology.

Many models used in theoretical ecology, or mathematical epidemiology are stochastic, and may also be spatially-explicit. Techniques from quantum field theory have been used before in reaction-diffusion systems, principally to investigate their critical behavior. Here we argue that they make many ca...

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Main Authors: Peter J Dodd, Neil M Ferguson
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2009-09-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC2734401?pdf=render
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author Peter J Dodd
Neil M Ferguson
author_facet Peter J Dodd
Neil M Ferguson
author_sort Peter J Dodd
collection DOAJ
description Many models used in theoretical ecology, or mathematical epidemiology are stochastic, and may also be spatially-explicit. Techniques from quantum field theory have been used before in reaction-diffusion systems, principally to investigate their critical behavior. Here we argue that they make many calculations easier and are a possible starting point for new approximations.We review the many-body field formalism for Markov processes and illustrate how to apply it to a 'Brownian bug' population model, and to an epidemic model. We show how the master equation and the moment hierarchy can both be written in particularly compact forms. The introduction of functional methods allows the systematic computation of the effective action, which gives the dynamics of mean quantities. We obtain the 1-loop approximation to the effective action for general (space-) translation invariant systems, and thus approximations to the non-equilibrium dynamics of the mean fields.The master equations for spatial stochastic systems normally take a neater form in the many-body field formalism. One can write down the dynamics for generating functional of physically-relevant moments, equivalent to the whole moment hierarchy. The 1-loop dynamics of the mean fields are the same as those of a particular moment-closure.
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spelling doaj.art-76a16c2ce70d4d30b59e2798368aba912022-12-21T19:09:54ZengPublic Library of Science (PLoS)PLoS ONE1932-62032009-09-0149e685510.1371/journal.pone.0006855A many-body field theory approach to stochastic models in population biology.Peter J DoddNeil M FergusonMany models used in theoretical ecology, or mathematical epidemiology are stochastic, and may also be spatially-explicit. Techniques from quantum field theory have been used before in reaction-diffusion systems, principally to investigate their critical behavior. Here we argue that they make many calculations easier and are a possible starting point for new approximations.We review the many-body field formalism for Markov processes and illustrate how to apply it to a 'Brownian bug' population model, and to an epidemic model. We show how the master equation and the moment hierarchy can both be written in particularly compact forms. The introduction of functional methods allows the systematic computation of the effective action, which gives the dynamics of mean quantities. We obtain the 1-loop approximation to the effective action for general (space-) translation invariant systems, and thus approximations to the non-equilibrium dynamics of the mean fields.The master equations for spatial stochastic systems normally take a neater form in the many-body field formalism. One can write down the dynamics for generating functional of physically-relevant moments, equivalent to the whole moment hierarchy. The 1-loop dynamics of the mean fields are the same as those of a particular moment-closure.http://europepmc.org/articles/PMC2734401?pdf=render
spellingShingle Peter J Dodd
Neil M Ferguson
A many-body field theory approach to stochastic models in population biology.
PLoS ONE
title A many-body field theory approach to stochastic models in population biology.
title_full A many-body field theory approach to stochastic models in population biology.
title_fullStr A many-body field theory approach to stochastic models in population biology.
title_full_unstemmed A many-body field theory approach to stochastic models in population biology.
title_short A many-body field theory approach to stochastic models in population biology.
title_sort many body field theory approach to stochastic models in population biology
url http://europepmc.org/articles/PMC2734401?pdf=render
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