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Applied Mathematics Colloquium
Friday, October 3, 11:30 am
Cullimore Lecture Hall II
New
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Group Dynamics in Phototaxis
Doron Levy
Department of Mathematics and CSCAMM
College Park, MD
Abstract
Microbes live in environments that are often limiting for growth. They have evolved sophisticated mechanisms to
sense changes in
environmental parameters such as
light and nutrients, after which they swim
or crawl into optimal conditions. This phenomenon is known as
''chemotaxis'' or
''phototaxis.'' Using time-lapse video
microscopy we have monitored the movement of phototactic bacteria, i.e.,
bacteria
that move towards light. These
movies suggest that single cells are able to move directionally but at the same
time, the group dynamics is
equally important. Following these observations, in this talk
we will present a hierarchy of mathematical models for phototaxis: a
stochastic model, an interacting particle
system, and a system of PDEs. We will discuss the models, their
simulations, and our theorems
that show how the system of PDEs
can be considered as the limit dynamics of the particle system. This is a joint work with Devaki
Bhaya (Department of Plant Biology, Carnegie Institute) and Tiago Requeijo (Math, Stanford).