Grant: Discovery Grants Program - Individual

This research program is aimed at the global dynamics of nonlinear evolution systems with spatial and temporal heterogeneities, which are inspired by population biology and epidemiology. We will study the existence, uniqueness and global stability of steady states and periodic solutions, persistence and extinction, global converegnce and attractors, the existence, uniqueness and stability of traveling waves, and asymptotic speeds of spread (in short, spreading speeds). In this project we also propose to obtain general results on spreading speeds and monostable traveling waves for abstract evolution systems, the existence and global stability of bistable waves for monotone semiflows, and basic reproduction numbers for nonautonomous epidemic models. The investigation methods involve dynamical systems, Liapunov functions, upper-lower solutions, perturbations and bifurcations, comparison principle, skew-product semiflows, linearization, nonlinear analysis, and numerical simulations. The novelty of the research lies in the dynamical systems approach to evolution equations with spatial-temporal structure. The proposed research is expected to establish the mathematical theory of spatial-temporal dynamics and biological invasions, and to develop the theory of nonautonomous dynamical systems. Progress in this project can also help to answer important questions such as whether and how a community of interacting populations can persist (avoid extinction) or whether an infectious disease becomes endemic in a population, to estimate the speeds of biological invasion and epidemic spreading, and to understand biological phenomena such as spatial-temporal patterns and wave propagations.