"This book is the distillation of the research conducted during my postdoctoral period, but some of its central insights were already formed during my doctoral studies. I therefore owe an immense debt of gratitude to my supervisors, the late Juha Sihvola, Mikko Yrjonsuuri, and Taneli Kukkonen. The extremely conscientious and insightful comments of Jon McGinnis and Simo Knuuttila provided crucial corroboration and realignment at a formative stage"--