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Seminar Details

Chaos and Levy walks in swarming bacteria

Date

24/05/2018

Lecturers

Prof. Gil Ariel - Dept. of Mathematics, Bar-Ilan University

Abstract

Individual swimming bacteria are known to bias their random trajectories in search of food and to optimize survival. The motion of bacteria within a swarm, wherein they migrate as a collective group over a solid surface, is fundamentally different as typical bacterial swarms show large-scale swirling and streaming motions involving millions to billions of cells. By tracking trajectories of fluorescently labelled individuals within such dense swarms, we find that the bacteria are performing super-diffusion, consistent with Levy walks. Levy walks are characterized by trajectories that have straight stretches for extended lengths whose variance is infinite. A simplified model suggests that the coupling between the individual and group dynamics leads to chaos, which changes the trajectories of cells from normal diffusion to a Levy walk. Mathematically, the model presents a new mechanism for Levy walks in chaotic systems. Biologically, it explains how cells can fine-tune the geometric properties of their trajectories.

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