KTH/SU Mathematics Colloquium

2005-04-27

Henri Berestycki (EHESS - Paris)

Reaction - diffusion equations and propagation phenomena

Front or pulse propagation phenomena arise in a variety of contexts such as flames, chemical reactions, phase transitions, biological invasions and even social behaviors. Equations and systems of reaction-diffusion (possibly with transport or advection terms) have long been used to describe these phenomena. In this lecture, after recalling these models, I will survey some of the classical results dealing with the homogeneous reaction-diffusion equation, focusing on propagation of fronts and asymptotic speed of spreading. Then I will present some generalizations regarding propagation in heterogeneous media. I will discuss in particular biological invasions in periodic heterogeneous media as well as a model for species facing a climate change. The results emphasize some new effects due to heterogeneity.