3:00 pm: Refreshments in LD 259
3:30 pm: Colloquium in LD 229
The ability of animals to self-organize into remarkable patterns of movement is seen throughout nature from herds of large mammals, to flocks of birds, schools of fish, and swarms of insects. Remarkably, patterns of collective movement can be seen even in the simplest forms of life such as bacteria. M. xanthus are common soil bacteria that are among the most "social" bacteria in nature. In this talk clustering mechanism of swarming M. xanthus will be described using combination of experimental movies and model simulations. Population of bacteria P. aeruginosa, main infection in hospitals, will be also shown to propagate as high density waves that move symmetrically as rings within swarms towards the extending tendrils. Biologically-justified cell-based multiscale model simulations suggest a mechanism of wave propagation as well as branched tendril formation at the edge of the population that depend upon competition between the changing viscosity of the bacterial liquid suspen sion and the liquid film boundary expansion caused by Marangoni forces. The model predictions of wave speed and swarm expansion rate as well as cell alignment in tendrils were confirmed experimentally. In the second half of the talk, derivation of continuous limits of discrete stochastic dynamical systems describing cell aggregation will be described in the form of reaction-diffusion and nonlinear diffusion equations. Existence and stability of different classes of solutions of such equations will be also discussed.
Note: If you would like to meet with Dr. Alber, please contact Alexey Kuznetsov at email@example.com.
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