I would like to express my gratitude to my supervisor, George Gerrity, and my co-supervisor, Lawrie Brown, for their criticisms, insights, thoughtful suggestions and continual prodding during the course of this study.
This thesis is dedicated to my fiancée Lynne Smith: without her support and encouragement, this work may not have been completed.
This thesis is set in Adobe Palatino, Computer Modern Typewriter and Computer
Modern Math using LATEX2e and dvips version 5.58. Figures were drawn
with xfig version 3.1.3, and converted to PostScript. Graphs were created
with Gnuplot version 3.5 and converted through xfig to PostScript.