Retracting fronts induce spatio-temporal intermittency
  The intermittent route to spatio-temporal complexity is analyzed in a simple model which displays a subcritical bifurcation without hysteresis. A new type of spatio-temporal complexity is found, induced by fronts which "convectively clean" the perturbations around an unstable state. The mechanism which leads to the existence of these "retracting fronts" is analyzed in the frame of simple models. 
Pierre Coullet and Lorenz Kramer