Biomedical subjects

W S Gurney

Publications and source records attributed to W S Gurney.

11 recordsLinked to original sources

PubMed1985

Stage-structure models of populations with distinct growth and development processes.

We extend the repertoire of stage-structure models which can be described in terms of delay-differential equations, by analysing models where the processes of growth and development within a stage are distinct. This permits the use of delay-differential equation models in situations where both population numbers and total biomass are dynamically significant.

Aging↗

PubMed1984

The dynamics of population models with distributed maturation periods.

An integro-differential equation for the dynamics of a subpopulation of adults in a closed system where only the adults compete and where there is a distribution of maturation periods is described. We show how the careful choice of a general weighting function based on the gamma distribution with a shift in origin enables us to characterize adequately some observed maturation-period distributions, and also makes local stability and numerical analyses straightforward. Using these results we examine the progression in the behavior of the distributed-delay model as the distribution is narrowed toward the limit of a discrete delay. We conclude that while local stability properties approach those of the limiting equation very rapidly, the persistent fluctuation behavior converges more slowly, with the dominant period and maximum amplitude being least affected by the details of the distribution, and the fine structure of solutions being most sensitive. Finally, we examine the consequences for population modeling, and using several examples of insect populations, conclude that although quite often a full maturation-period distribution should be incorporated in a given model, in many cases a discrete-delay approximation will suffice.

Age Factors↗

PubMed1980