Interaction of coherent structures

The motivation for this work are "period-doubling" bifurcations of spiral waves in excitable media. The bifurcating spirals exhibit line defects across which the temporal phase of the period-doubling mode jumps. If there are several line defects present, then they begin to interact and, in fact, attract each other. Interacting coherent structures have been observed in many other situations as well. After giving an overview of the different types of coherent structures, I will describe an attempt to explain (some of) their interaction properties phenomena by spectral analyses.