LOCALIZATION OF WAVES WITHOUT BISTABILITY - WORMS IN NEMATIC ELECTROCONVECTION

A general localization mechanism for waves in dissipative systems is i dentified that does not require the bistability of the basic state and the nonlinear plane-wave state. We conjecture that the mechanism expl ains the two-dimensional localized wave structures (''worms'') that re cently have been observed in experiments on electroconvection in nemat ic liquid crystals where the transition to extended waves is supercrit ical. The mechanism accounts for the shape of the worms, their propaga tion direction, and certain aspects of their interaction. The dynamics of the localized waves can be steady or irregular. [S0031-9007(98)065 60-0].