Motion of Euglena gracilis: Active fluctuations and velocity distribution

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Title: Motion of Euglena gracilis: Active fluctuations and velocity distribution
Authors: Romanczuk, M.
Romensky, Maksym
Scholz, Dimitri
Lobaskin, Vladimir
Schimansky-Geier, L.
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Date: Jul-2015
Abstract: We study the velocity distribution of unicellular swimming algae Euglena gracilis using optical microscopy and active Brownian particle theory. To characterize a peculiar feature of the experimentally observed distribution at small velocities we use the concept of active fluctuations, which was recently proposed for the description of stochastically self-propelled particles [Romanczuk, P. and Schimansky-Geier, L., Phys. Rev. Lett. 106, 230601 (2011)]. In this concept, the fluctuating forces arise due to internal random performance of the propulsive motor. The fluctuating forces are directed in parallel to the heading direction, in which the propulsion acts. In the theory, we introduce the active motion via the depot model [Schweitzer, et al., Phys. Rev. Lett. 80(23), 5044 (1998)]. We demonstrate that the theoretical predictions based on the depot model with active fluctuations are consistent with the experimentally observed velocity distributions. In addition to the model with additive active noise, we obtain theoretical results for a constant propulsion with multiplicative noise.
Type of material: Journal Article
Publisher: Springer
Copyright (published version): 2015 EDP Sciences, Springer
Keywords: Euglena gracilis;Behaviour
DOI: 10.1140/epjst/e2015-02456-1
Language: en
Status of Item: Peer reviewed
Appears in Collections:Conway Institute Research Collection
Physics Research Collection
CASL Research Collection

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