This paper proposes a novel chaotic reaction-diffusion model of cellular tumor growth and metastasis. The model is based on the multiscale diffusion cancer-invasion model (MDCM) and formulated by introducing strong nonlinear coupling into the MDCM. The new model exhibits temporal chaotic behavior (which resembles the classical Lorenz strange attractor) and yet retains all the characteristics of...

The classic Beverton-Holt (discrete logistic) difference equation, which arises in population dynamics, has a globally asymptotically stable equilibrium (for positive initial conditions) if its coefficients are constants. If the coefficients change in time, then the equation becomes nonautonomous and the asymptotic dynamicsmight not be as simple. One reason the coefficients can change in time i...

General dynamic models of systems with two prey and one or two predators are considered. After rescaling the equations so that both prey have the same intrinsic rate of growth, it is shown that there exists a generalist predator that can mediate permanence if and only if there is a population density of a prey at which its per-capita growth rate is positive yet less than its competitor’s invasi...

We consider a new interacting particle system on the one-dimensional lattice that interpolates between TASEP and Toom’s model: A particle cannot jump to the right if the neighboring site is occupied, and when jumping to the left it simply pushes all the neighbors that block its way. We prove that for flat and step initial conditions, the large time fluctuations of the height function of the ass...

We use feedback control methods to prove existence of globally asymptotically stable equilibria for nonlinear (density dependent) population dynamics. We focus on populations modelled in discrete size or stage classes so that the model has a natural state space of nonnegative vectors in R. Combining comparison results and small gain techniques, we characterize the situations when there is a pos...

We estimate a structural model of schooling, labor supply and life-cycle earnings in which some individuals have comparative advantage in producing skills in school while others are better at producing skills in the labor market and analyze some of its key implications. The model is estimated using a sample of white males taken from the 1979 cohort of the National Longitudinal Survey of Youth (...

We state conditions for existence and uniqueness of equilibria in dynamic microeconomic models with an infinity of locally and globally interacting agents. Agents face repeated discrete choice problems. Their utility depends on the actions of some designated neighbors and the average choice throughout the whole population. We show that the dynamics on the level of aggregate behavior can be desc...

In this paper, we study a flower population in which self-reproduction is not permitted. Individuals are diploid, that is, each cell contains two sets of chromosomes, and distylous, that is, two alleles, A and a, can be found at the considered locus S. Pollen and ovules of flowers with the same genotype at locus S cannot mate. This prevents the pollen of a given flower from fecundating its own ...

Cauchy problem in a product space (that may be particularly involved). For example, consider the heat equation  ∂u ∂t (t, x) = ∆u(t, x), t ≥ 0, x ∈ Ω, ∂w ∂t (t, z) = − ∂w ∂n (t, z), t ≥ 0, z ∈ ∂Ω, w(t, z) = u(t, z), t ≥ 0, z ∈ ∂Ω, where − ∂ ∂n denotes the outer normal derivative. This can be written as U ′(t) = ( ∆ 0 − ∂ ∂n 0 ) U(t), where U = ( u u|∂Ω ) . Observe that a relationship between ...

When a new mutant arises in a population, there is a probability it outcompetes the residents and fixes. The structure of the population can affect this fixation probability. Suppressing population structures reduce the difference between two competing variants, while amplifying population structures enhance the difference. Suppressors are ubiquitous and easy to construct, but amplifiers for th...