This book covers work in the broad area of the scientific interests of Rainer Picard's research work marking Rainer's 80th birthday. Thus, it contains numerous articles provided by his friends and colleagues from the areas of partial differential equations-both time-dependent and time-independent-from operator theory including topics such as monotonicity and particular operator theoretic applications to questions arising in partial differential equations or numerics, and from mathematical physics detailing the impact of functional analysis to the most recent models describing physical processes in nature.