This monograph evolved over the past five years. It had its origin as a
set of lecture notes prepared for the Ninth Summer School of
Mathematical Physics held at Ravello, Italy, in 1984 and was further
refined in seminars and lectures given primarily at the University of
Colorado. The material presented is the product of a single mathematical
question raised by Dave Kassoy over ten years ago. This question and its
partial resolution led to a successful, exciting, almost unique
interdisciplinary col- laborative scientific effort. The mathematical
models described are often times deceptively simple in appearance. But
they exhibit a mathematical richness and beauty that belies that
simplicity and affirms their physical significance. The mathe- matical
tools required to resolve the various problems raised are diverse, and
no systematic attempt is made to give the necessary mathematical
background. The unifying theme of the monograph is the set of models
themselves. This monograph would never have come to fruition without the
enthu- siasm and drive of Dave Eberly-a former student, now collaborator
and coauthor-and without several significant breakthroughs in our
understand- ing of the phenomena of blowup or thermal runaway which
certain models discussed possess. A collaborator and former student who
has made significant contribu- tions throughout is Alberto Bressan.
There are many other collaborators- William Troy, Watson Fulks, Andrew
Lacey, Klaus Schmitt-and former students-Paul Talaga and Richard Ely-who
must be acknowledged and thanked.