NONLINEAR STAGE OF INSTABILITY EVOLUTION IN A MONOSTABLE ACTIVE MEDIUM

A theoretical analysis is made of the nonlinear stage of instability e volution in a monostable active medium described by a ''reaction-diffu sion'' type equation. The boundary of that region of the medium in whi ch instability develops propagates at constant velocity. Group-theoret ical analysis of the problem yields an analytic expression for the pro pagation velocity of this boundary. The results may be important for t he analysis of instability evolution in a wide range of active media. (C) 1998 American Institute of Physics.