title: Spiral and never-settling patterns in active systems.
abstract: We present a combined numerical and analytical study of pattern formation in an active system where particles align, possess a density-dependent motility, and are subject to a logistic reaction. The model can describe suspensions of reproducing bacteria, as well as polymerizing actomyosin gels in vitro or in vivo. In the disordered phase, we find that motility suppression and growth compete to yield stable or blinking patterns, which, when dense enough, acquire internal orientational ordering to give asters or spirals. We predict these may be observed within chemotactic aggregates in bacterial fluids. In the ordered phase, the reaction term leads to previously unobserved never-settling patterns which can provide a simple framework to understand the formation of motile and spiral patterns in intracellular actin systems.
authors.affiliation: Physics Department, Syracuse University, Syracuse, New York 13244, USA.
authors.forename: X
authors.initials: X
authors.lastname: Yang
authors.affiliation: SUPA, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh EH93JZ, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Marenduzzo
authors.affiliation: Physics Department and Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York 13244, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Marchetti
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000502:physiology*; D001683:Biological Clocks / Q000502:physiology*; D003102:Colloids / Q000737:chemistry*; D003198:Computer Simulation; D008954:Models, Biological; D008956:Models, Chemical; D009038:Motion
chemical_list: D003102:Colloids