Organization and instabilities of entangled active polar filaments
  We study the dynamics of an entangled, isotropic solution of polar filaments coupled by molecular motors which generate relative motion of the filaments in two and three dimensions. We investigate the stability of the homogeneous state for constant motor concentration taking into account excluded volume and entanglement. At low filament density the system develops a density instability, while at high filament density entanglement effects drive the instability of orientational fluctuations. 
Tanniemola B. Liverpool (Imperial College) and M. Cristina Marchetti   (Syracuse University)