BY

This dissertation would have been possible without the assistance, guidance and support I received from so many people along the way. It is not possible to acknowledge everyone who enlightened, encouraged, and helped me complete this work, but I would like to make special mention of the following people and institutions. First of all, I would like to express my deep gratitude to my advisor, Dr. Fred Finley, for the source of knowledge, guidance and support that he has given me during my graduate studies. His understanding, immense guidance, and continuous encouragement helped me go through the difficulties and challenges that inevitably arise throughout a graduate student's life at the University of Minnesota. He always guided me in the right direction, but allowed me to develop at my own pace. I would like to send my sincere thanks to my doctoral committee members, Dr. Bhaskar Upadhyay, Dr. Gillian Roehrig, and Dr. Kenneth Heller, for their interest in my thesis work and for their helpful suggestions. I also want to thank all the professors at the University of Minnesota who provided me with great education and knowledge. I always feel very proud of being a graduate student there