The discovery of superconductivity at 30 K by Bednorz and Müller in 1986 ignited an explosion of interest in high temperature superconductivity. The initial development rapidly evolved into an intensive worldwide research effort — which still persists after more than a decade — to understand the phenomenon of cuprate superconductivity, to search for ways to raise the transition temperature and to produce materials which have the potential for technological applications.During the past decade of research on this subject, significant progress has been made on both the...

Nonl inear ideas of a "sol iton" variety have been a unifying influence on the na tura 1 sci ences for many decades. HO~/ever, thei r uni versa 1 a pprec i at i on in the physics community as a genuine paradigm is very much a current develop- ment. All of us who have been associated with this recent wave of enthusiasm were impressed with the variety of applications, their inevitability once the mental contraint of linear normal modes is removed, and above all by the common mathematical structures underpinning applications with quite different (and often novel) physical manifestations. This...