A linear model for an age-structured population with random diiusion in a bounded domain R n is studied in the semigroup framework in L 2. Three diierent approaches to establishing well-posedness of the problem are presented. Two of them involve applying known results on the m-dissipativeness of the sum of two m-dissipative operators to the population operator and the diiusion operator. 1. Intr...

Existence of nontrivial nonnegative equilibrium solutions for age structured population models with nonlinear diffusion is investigated. Introducing a parameter measuring the intensity of the fertility, global bifurcation is shown of a branch of positive equilibrium solutions emanating from the trivial equilibrium. Moreover, for the parameter-independent model we establish existence of positive...

This paper is devoted to study the null controllability properties of a nonlinear age and two-sex population dynamics structured model without spatial structure. Here, nonlinearity couplage are at birth level. In this work, we consider two cases problem. The first problem related extinction male female subpopulation density. second case concerns or individuals. both cases, if <math xmlns="http:...

This paper is a contribution to the modeling–methodological development of application mathematical systems theory in population biology. A discrete-time nonlinear Leslie-type model considered, where both reproduction and survival rates decrease as total size increases. In this context, monitoring problem means that, from observation certain age classes function time, we want recover (estimate)...

In [13] Prüß investigated a very general nonlinear age-structured model consisting of n species. He proved the principle of linearized stability, which means that the asymptotic behavior of stationary solutions of the nonlinear system is determined by the spectrum of the linearized operator. In other words the stability is determined by the roots of a complex valued characteristic function as i...

Our goal in this note is to present a general approach to define the net reproduction function/functional for a large class of nonlinear physiologically structured population models. In particular, we are going to show that this can be achieved in a natural way by reformulating a general nonlinear problem as a family of linear problems; each of the linear problems describing the evolution of th...