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In this paper, we review recent developments on the derivation and properties of macroscopic models of collective motion and self-organization. The starting point is a model of self-propelled particles interacting with its neighbors through alignment. We successively derive a mean-field model and its hydrodynamic limit. The resulting macroscopic model is the Self-Organized Hydrodynamics (SOH). We review the available existence results and known properties of the SOH model and discuss it in view...
This note contains a survey of recent results concerning asymptotic properties of Markov operators and semigroups. Some biological and physical applications are given.
The cancer stem cell hypothesis has evolved to one of the most important paradigms in
biomedical research. During recent years evidence has been accumulating for the existence
of stem cell-like populations in different cancers, especially in leukemias. In the
current work we propose a mathematical model of cancer stem cell dynamics in leukemias. We
apply the model to compare cellular properties of leukemic stem cells to those of their
benign counterparts....
Modification of behaviour in response to changes in the environment or ambient
conditions, based on memory, is typical of the human and, possibly, many animal
species.One obvious example of such adaptivity is, for instance, switching to a safer
behaviour when in danger, from either a predator or an infectious disease. In human
society such switching to safe behaviour is particularly apparent during epidemics.
Mathematically, such changes of behaviour...
This contribution reviews the nonlinear
stochastic properties of turbulent velocity and passive scalar
intermittent fluctuations in Eulerian and Lagrangian turbulence.
These properties are illustrated with original data sets of (i)
velocity fluctuations collected in the field and in the
laboratory, and (ii) temperature, salinity and in vivo
fluorescence (a proxy of phytoplankton biomass, i.e. unicelled
vegetals passively advected by turbulence) sampled from highly
turbulent coastal waters. The strength...
We consider a mathematical model of nutrient-autotroph-herbivore interaction with nutrient recycling from both autotroph and herbivore. Local and global stability criteria of the model are studied in terms of system parameters. Next we incorporate the time required for recycling of nutrient from herbivore as a constant discrete time delay. The resulting DDE model is analyzed regarding stability and bifurcation aspects. Finally, we assume the recycling delay in the oscillatory form to model the...
In this paper we are interested in a mathematical model of migration of grass eels in an estuary. We first revisit a previous model proposed by O. Arino and based on a degenerate convection-diffusion equation of parabolic-hyperbolic type with time-varying subdomains. Then, we propose an adapted mathematical framework for this model, we prove a result of existence of a weak solution and we propose some numerical simulations.
We consider an ecosystem in which
spiders may be transported by the wind from vineyards into the
surrounding woods and vice versa. The model takes into account
this tranport phenomenon without building space explicitly into
the governing equations. The equilibria of the dynamical system
are analyzed together with their stability, showing that
bifurcations may occur. Then the effects of indiscriminated
spraying to keep pests under control is also investigated via
suitable simulations.
This article discusses a prey-predator system with cross-diffusion. We obtain multiple positive steady-state solutions of this system. More precisely, we prove that the set of positive steady-states possibly contains an S or ⊃-shaped branch with respect to a bifurcation parameter in the large cross-diffusion case. Next we give some criteria on the stability of these positive steady-states. Furthermore, we find the Hopf bifurcation point on the steady-state solution branch in a certain case. Our...
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