title: Symmetry-breaking motility.
abstract: Locomotion of bacteria by actin polymerization and in vitro motion of spherical beads coated with a protein catalyzing polymerization are examples of active motility. Starting from a simple model of forces locally normal to the surface of a bead, we construct a phenomenological equation for its motion. The singularities at a continuous transition between moving and stationary beads are shown to be related to the symmetries of its shape. Universal features of the phase behavior are calculated analytically and confirmed by simulations. Fluctuations in velocity are shown to be generically non-Maxwellian and correlated to the shape of the bead.
authors.affiliation: Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Allen
authors.initials: A
authors.lastname: Lee
authors.forename: Ha Youn
authors.initials: HY
authors.lastname: Lee
authors.forename: Mehran
authors.initials: M
authors.lastname: Kardar
mesh_terms: D000199:Actins / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D008087:Listeria / Q000378:metabolism / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism; D008954:Models, Biological; D008962:Models, Theoretical; D009068:Movement; D013269:Stochastic Processes; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism
chemical_list: D000199:Actins; D001426:Bacterial Proteins; D008565:Membrane Proteins; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; C072980:actA protein, Listeria monocytogenes