dorsal/arxiv
View SchemaActive Brownian Particle and Random Walk Theories of the Motions of Zooplankton: Application to Experiments with Swarms of Daphnia
| Authors | Udo Erdmann, Werner Ebeling, Lutz Schimansky-Geier, Anke Ordemann, Frank Moss |
|---|---|
| Categories | |
| ArXiv ID | q-bio/0404018 |
| URL | https://arxiv.org/abs/q-bio/0404018 |
Abstract
Active Brownian Particles are self-propelled particles that move in a dissipative medium subject to random forces, or noise . Additionally, they can be confined by an external field and/or they can interact with one another. The external field may actually be an attractive marker, for example a light field (as in the experiment) or an energy potential or a chemical gradient (as in the theory). The potential energy can also be the result of interparticle attractive and/or repulsive forces summed over all particles (a mean field potential). Four, qualitatively different motions of the particles are possible: at small particle density their motions are approximately independent of one another subject only to the external field and the noise, which results in moving randomly through or performing rotational motions about a central point in space. At increasing densities interactions play an important role and individuals form a swarm performing several types of self-organized collective motion. We apply this model for the description of zooplankton Daphnia swarms. In the case of the zooplankton Daphnia (and probably many other aquatic animals that form similar motions as well) this vortex is hydrodynamical but motivated by the self-propelled motion of the individuals. Similar vortex-type motions have been observed for other creatures ranging in size from bacteria to flocks of birds and schools of fish. However, our experiment with Daphnia is unique in that all four motions can be observed in controlled laboratory conditions with the same animal. Moreover, the theory, presented in both continuous differential equation and random walk forms, offers a quantitative, physically based explanation of the four motions.
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"abstract": "Active Brownian Particles are self-propelled particles that move in a\ndissipative medium subject to random forces, or noise . Additionally, they can\nbe confined by an external field and/or they can interact with one another. The\nexternal field may actually be an attractive marker, for example a light field\n(as in the experiment) or an energy potential or a chemical gradient (as in the\ntheory). The potential energy can also be the result of interparticle\nattractive and/or repulsive forces summed over all particles (a mean field\npotential). Four, qualitatively different motions of the particles are\npossible: at small particle density their motions are approximately independent\nof one another subject only to the external field and the noise, which results\nin moving randomly through or performing rotational motions about a central\npoint in space. At increasing densities interactions play an important role and\nindividuals form a swarm performing several types of self-organized collective\nmotion. We apply this model for the description of zooplankton Daphnia swarms.\nIn the case of the zooplankton Daphnia (and probably many other aquatic animals\nthat form similar motions as well) this vortex is hydrodynamical but motivated\nby the self-propelled motion of the individuals. Similar vortex-type motions\nhave been observed for other creatures ranging in size from bacteria to flocks\nof birds and schools of fish. However, our experiment with Daphnia is unique in\nthat all four motions can be observed in controlled laboratory conditions with\nthe same animal. Moreover, the theory, presented in both continuous\ndifferential equation and random walk forms, offers a quantitative, physically\nbased explanation of the four motions.",
"arxiv_id": "q-bio/0404018",
"authors": [
"Udo Erdmann",
"Werner Ebeling",
"Lutz Schimansky-Geier",
"Anke Ordemann",
"Frank Moss"
],
"categories": [
"q-bio.PE",
"cond-mat.stat-mech",
"physics.bio-ph"
],
"title": "Active Brownian Particle and Random Walk Theories of the Motions of Zooplankton: Application to Experiments with Swarms of Daphnia",
"url": "https://arxiv.org/abs/q-bio/0404018"
},
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