The new transportation and communication possibilities have triggered an extensive and rapidly growing international network of scientific collaboration. In this volume, the contributions cover a variety of topics as can be seen from the contents. Despite this manifest disparity between the different topics, there is of course a unifying methodological factor in the theory of dynamical systems, which plays a paramount role in all the studies presented here. So the diversity of subjects is just one expression of the enormous spectrum of areas where the theory of dynamical systems has found applications during the past two decades.