Nonequilibrium phase transitions in active contractile polar filaments
  We study the patterning and fluctuations of a collection of active contractile polar filaments on a two dimensional substrate, using a continuum description in the presence of athermal noise, parameterised by an active temperature $T_A$. The steady states generically consist of arrays of inward pointing asters and show a continuous transition from a moving aster street to a stationary aster lattice. In contrast to its equilibrium counterpart, this active crystal shows true long range order at low $T_A$. On increasing $T_A$, the asters remodel with a distribution of lifetimes; concomitantly we find novel phase transitions characterised by polar and bond-orientational order. 
Kripa Gowrishankar and Madan Rao
cond-mat.soft cond-mat.stat-mech physics.bio-ph