Defect dynamics in active nematics
  Topological defects are distinctive signatures of liquid crystals. They profoundly affect the viscoelastic behavior of the fluid by constraining the orientational structure in a way that inevitably requires global changes not achievable with any set of local deformations. In active nematic liquid crystals topological defects not only dictate the global structure of the director, but also act as local sources of motion, behaving as self-propelled particles. In this article we present a detailed analytical and numerical study of the mechanics of topological defects in active nematic liquid crystals. 
Luca Giomi, Mark J. Bowick, Prashant Mishra, Rastko Sknepnek, M.   Cristina Marchetti
cond-mat.soft