String Propagation in Bianchi Type I models: Dynamical anisotropy   Damping and Consequences
  A generic ansatz is introduced which provides families of exact solutions to the equations of motion and constraints for null-strings in Bianchi type I cosmological models. This is achieved irrespective of the form of the metric. Within classes of dilaton cosmologies a backreaction mapping relation is established where the null string leads to more or less anisotropic members of the family. The equations of motion and constraints for the generic model are casted in their first order form and integrated both analytically and numerically. 
A. Kuiroukidis, K. Kleidis and D. B. Papadopoulos