Population dynamics control in regard to minimizing the time necessary for the regeneration of a biomass taken away from the population
Population dynamics of Bithynia tentaculata
Population Dynamics of Grayling: Modelling Temperature and Discharge Effects
We propose a matrix population modelling approach in order to describe the dynamics of a grayling (Thymallus thymallus, L. 1758) population living in the Ain river (France). We built a Leslie like model, which integrates the climate changes in terms of temperature and discharge. First, we show how temperature and discharge can be related to life history traits like survival and reproduction. Second, we show how to use the population model to precisely examine the life cycle of grayling : estimated...
Population dynamics with symmetric and asymmetric harvesting.
Population genetics models for the statistics of DNA samples under different demographic scenarios - Maximum likelihood versus approximate methods
The paper reviews the basic mathematical methodology of modeling neutral genetic evolution, including the statistics of the Fisher-Wright process, models of mutation and the coalescence method under various demographic scenarios. The basic approach is the use of maximum likelihood techniques. However, due to computational problems, intuitive or approximate methods are also of great importance.
Population growth and environment as a self-organizing system.
Population Growth and Persistence in a Heterogeneous Environment: the Role of Diffusion and Advection
The spatio-temporal dynamics of a population present one of the most fascinating aspects and challenges for ecological modelling. In this article we review some simple mathematical models, based on one dimensional reaction-diffusion-advection equations, for the growth of a population on a heterogeneous habitat. Considering a number of models of increasing complexity we investigate the often contrary roles of advection and diffusion for the persistence of the population. When it is possible we demonstrate...
Population growth and the environment: Can we eat the cake and have it?
Populational adaptive evolution, chemotherapeutic resistance and multiple anti-cancer therapies
Resistance to chemotherapies, particularly to anticancer treatments, is an increasing medical concern. Among the many mechanisms at work in cancers, one of the most important is the selection of tumor cells expressing resistance genes or phenotypes. Motivated by the theory of mutation-selection in adaptive evolution, we propose a model based on a continuous variable that represents the expression level of a resistance gene (or genes, yielding a phenotype) influencing in healthy and tumor cells birth/death...
Population-size-dependent branching processes.
Positive almost automorphic solutions for some nonlinear delay integral equations.
Positive almost periodic solutions of non-autonomous delay competitive systems with weak allee effect.
Positive and Negative Feedback in Engineering and Biology
No other concepts have shaken so deeply the bases of engineering like those of positive and negative feedback. They have played a most prominent role in engineering since the beginning of the previous century. The birth certificate of positive feedback can be traced back to a pair of patents by Edwin H. Armstrong in 1914 and 1922, whereas that of negative feedback is already lost in time. We present in this paper a short review on the feedback's origins in the fields of engineering and biology....
Positive fixed point theorems arising from seeking steady states of neural networks
Biological systems are able to switch their neural systems into inhibitory states and it is therefore important to build mathematical models that can explain such phenomena. If we interpret such inhibitory modes as `positive' or `negative' steady states of neural networks, then we will need to find the corresponding fixed points. This paper shows positive fixed point theorems for a particular class of cellular neural networks whose neuron units are placed at the vertices of a regular polygon. The...
Positive global solutions for a general model of size-dependent population dynamics.
Positive periodic solution for ratio-dependent -species discrete time system
In this paper, sharp a priori estimate of the periodic solutions is obtained for the discrete analogue of the continuous time ratio-dependent predator-prey system, which is governed by nonautonomous difference equations, modelling the dynamics of the competing preys and one predator having nonoverlapping generations. Based on more precise a priori estimate and the continuation theorem of the coincidence degree, an easily verifiable sufficient criterion of the existence of positive periodic solutions...
Positive periodic solutions for a predator-prey model with time delays and impulsive effect.
Positive periodic solutions for an impulsive ratio-dependent predator-prey system with delays.
Positive periodic solutions for nonlinear difference equations via a continuation theorem.
Positive periodic solutions of a discrete mutualism model with time delays.