for their time, support and guidance. I would like to express my gratitude to my co-major professors: Dr. Kannan Raghunandan and Dr. Dasaratha Rama for their gentle support, useful comments and tireless supervision. I would like to thank my wife, Lemane Kaba, for staying by my side throughout this journey. Without her never-failing sympathy, patience, endurance, encouragement and even sacrifice, this journey wouldn't have been possible. v