It is a great pleasure for me to thank the people who have helped me during my PhD. First and foremost, I am indebted to my supervisor, Dr. Ramakrishna Kakarala. I am thankful to him for the amount of independence he gave me during my PhD, which allowed me to grow as a researcher. I would also like to thank him for the confidence he has showed in me and the patience that he had during some of the difficult times in my research. I am also thankful to him for always keeping his door open for me to discuss my research problems, many of which have gone on for long periods of time. Finally, I am grateful for the support and motivation that he has provided during the course of my PhD. Secondly, I would like to thank my parents, V. R. Premachandran and Priya Premachandran, for all the help, motivation, love and support that they have provided. I am thankful to them for supporting me in my decision to embark on doctoral studies. It would have been impossible to complete this thesis without the confidence that I had the support, and help, of my parents during the entire period of my PhD.