A bioeconomic simulation model of the two interacting fish species cod (Gadus morhua) and capelin (Mallotus villosus) and their fisheries is presented and applied to assess the consequences of changes in the population dynamics of these important fish stocks in the Barents Sea. In each scenario, the population dynamics of the fish species are changed by reducing the reproduction-induced product...

By the use of Perron-Frobenius theory, simple proofs are given of the Fundamental Theorem of Demography and of a theorem of Cushing and Yicang on the net reproductive rate occurring in matrix models of population dynamics. The latter result is further refined with some additional nonnegative matrix theory. When the fertility matrix is scaled by the net reproductive rate, the growth rate of the ...

population dynamics is not confined to arrivals: immigrants have children after they arrive in France. These children by definition do not appear in the net migration count, but in the rate of natural increase [1]. How do we account for them in estimating the share of the French birth rate due to immigration? There are three ways of doing so, corresponding to three distinct questions. First, wh...

The gypsy moth, Lymantria dispar, is a major defoliator of deciduous trees throughout the northern hemisphere. Introduced into eastern Massachusetts from Europe in 1868 or 1869, it has gradually spread south and west and will soon occupy most of the hardwood forests in the eastern United States and Canada. The gypsy moth has been the subject of intensive study by scientists throughout the world...

A bioeconomic simulation model of the two interacting fish species cod (Gadus morhua) and capelin (Mallotus villosus) and their fisheries is presented and applied to assess the consequences of changes in the population dynamics of these important fish stocks in the Barents Sea. In each scenario, the population dynamics of the fish species are changed by an external reduction of the reproductive...

We generalize the Kolmogorov continuity theorem and prove of a class stochastic fields with parameter. As an application, we derive solutions for nonlocal parabolic equations driven by non-Gaussian Lévy noises.

The discussion on the relation between the Kolmogorov system, considered as low-order approximation of Navier–Stokes equations, and the well-known Lorenz equations is still not completely understood. In this Letter, referring to the mathematical theory of motion on Lie groups, a particular class of Kolmogorov systems, largely studied in low-dimensional models of geophysical fluid dynamics, is e...

We study the global existence and uniqueness of weak solutions to kinetic Kolmogorov–Vicsekmodels that canbe considered as non-local, non-linear, Fokker– Planck type equations describing the dynamics of individuals with orientational interactions. This model is derived from the discrete Couzin–Vicsek algorithm as mean-field limit (Bolley et al., Appl Math Lett, 25:339–343, 2012; Degond et al., ...

Extended systems governed by partial differential equations can, under suitable conditions, be approximated by means of sets of ordinary differential equations for global quantities capturing the essential features of the systems dynamics. Here we obtain a small number of effective equations describing the dynamics of single-front and localized solutions of Fisher-Kolmogorov type equations. The...