The interaction between a pair of Bloch fronts forming a traveling dom
ain in a bistable medium is studied. A parameter range beyond the none
quilibrium Ising-Bloch bifurcation is found where traveling domains co
llapse. Only beyond a second threshold the repulsive front interaction
s become strong enough to balance attractive interactions and asymmetr
ies in front speeds, and form stable traveling pulses, The analysis is
carried out for the forced complex Ginzburg-Landau equation. Similar
qualitative behavior is found in the bistable FitzHugh-Nagumo model. (
C) 1997 Published by Elsevier Science B.V.