Fisher Equation for a Decaying Brane
  We consider the inhomogeneous decay of an unstable D-brane. The dynamical equation that describes this process (in light-cone time) is a variant of the non-linear reaction-diffusion equation that first made its appearance in the pioneering work of (Luther and) Fisher and appears in a variety of natural phenomena. 
Debashis Ghoshal
hep-th cond-mat.stat-mech