OF THE UNIVERSITY OF MINNESOTA BY

First of all, I would like to thank my thesis advisor Prof. Demoz Gebre-Egziabher for his invaluable help and guidance throughout my PhD. He kept me focused and yet gave me wide latitude to explore new avenues which not only nourished my intellect, but provided me with the opportunity to savor every phase of my research. His insightful comments on a diverse range of topics- both technical and non-technical- have always enriched me and helped me broaden my perspectives. His help and initiatives to collect data for the last part of this thesis are greatly appreciated. I also owe him a great debt of gratitude for his careful reading of my thesis and for his thorough comments and suggestions. I would like to acknowledge the comments and suggestions of my defense com-mittee members Prof. Yiyuan Zhao, Prof. Peter Seiler and Prof. Max Donath. Special thanks are due to Prof. Seiler for his meticulous reading of my thesis. I also owe great thanks to Prof. Gary Balas whose constructive criticism during my Preliminary Oral Examination and group seminars has contributed greatly to improving the quality of my research. I would like to thank all my colleagues, past and present, (Chen-Chi Chu