IAM-PIMS-MITACS Distinguished Colloquium Series: Herbert Levine, Department of Physics (University of California at San Diego)

Individual biological cells make decisions as to where to go for food, when and how to divide, and when to engage in cooperative activities. These choices must be made by nonlinear dynamical systems often buffeted by large stochastic fluctuations. Understanding how this works, therefore, requires a novel blend of non-equilibrium statistical mechanics, mathematical modeling and cell biology. This talk will focus on several prototypical examples, all from the world of microorganisms. These include: amoeba chemotaxis (motion up chemical gradients) during aggregation; E. Coli cell division, where the challenge is to divide in a symmetric manner; and cooperative transitions between different types of branching patterns seen in Paenibacillus colony growth.

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Herb Levine received his doctoral degree from Princeton in 1979. He is currently a Professor of Physics at UCSD and a member of the Biophysics, Condensed Matter Physics, and Nonlinear Dynamics research groups. He is interested in the physics of nonequilibrium systems, especially in how these systems create nontrivial spatial patterns. Nonequilibrium dynamics usually involves the time evolution of a spatially extended set of degrees of freedom which evolve nonlinearly while interacting with each other via transport processes. Falling within this framework are problems that arise in physics and material science, chemical reaction kinetics and biological morphogenesis. Most recently, Herb's work has emphasized structures formed in micro-organism aggregation (both bacteria colonies and cellular slime mold), rotating waves that appear in a variety of nonlinear chemical systems (eg., CO catalysis on a metal surface), and the use of field theoretic approaches for the study of disordered and fractal patterns in crystallization.