Excitable patterns in active nematics
Original Entry: Peter Foster, AP 225, Fall 2011 In Progress...
Authors: L. Giomi, L. Mahadevan, B. Chakraborty, and M. F. Hagan
Publication: Giomi et al. Excitable Patterns in Active Nematics. Phys Rev Lett (2011)
This paper consists simulations of the dynamics of a two dimensional system of mutually propelled rods immersed in a solved. The modeling of this system is very similar to traditional models used to describe liquid crystals, but with terms added in order to accommodate the active nature of the mutual propulsion of the rods. It's the active nature of many biological systems (i.e. microtubule/motor systems) that differentiates them from passive liquid crystal systems and characterizes how the energy released by the consumption of fuel (ATP) is converted into mechanical motion.
The dynamics of an active system are governed by several timescales, including the timescale of active forcing (ta), the relaxation time of the nematic degrees of freedom (tp), the diffusive timescale, and the dissipative time scale of the solvent (td). When tp ~ta, a sort of balance can exist between the active forces, elastic distortion, and flow. When ta<<tp, the passive relaxation cannot keep up with the active driving and there will be a dynamic interplay between the active and passive forces. ==Discussion==,
 Giomi et al. Excitable Patterns in Active Nematics. Phys Rev Lett (2011)