Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 12: Joint focus session (with BP): Statistics of Cellular Motion

DY 12.5: Vortrag

Dienstag, 27. März 2012, 11:45–12:00, H 1028

Describing Run and Tumble Motion with Alternating Random Walks — •Felix Thiel, Lutz Schimansky-Geier, and Igor M. Sokolov — Institut für Physik der Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin

Run and tumble motion is the motile behaviour of flagellated bacteria like E.Coli. Much effort has been made in order to understand and describe such motion. Continuous time random walks (CTRW) are a common tool for description, but lack the possibility of incorporating different kinds of motion. In order to fill this gap, we present a modification of the usually considered CTRW: the alternating random walk. We explicitly distinguish between the run and the tumble phase. By using the techniques of CTRW -- integral transforms and asymptotic analysis -- we are able to obtain the short-time as well as the long-time behaviour of the mean squared displacement of the process. The main free parameters of the process governing the diffusive behaviour are the waiting-time-PDFs describing the dwelling time in run resp. tumble mode. It is shown that models constructed as above may exhibit a transition in diffusive behaviour from normal to superdiffusion and a change of the effective diffusion coefficient. They may thus be suitable to describe other situations which are known for those phenomena.

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