iii Acknowledgements I have no doubt that this thesis would never have been written without the encouragement and the aid of my professors, my parents, my friends and my colleagues. My parents, who managed to be supportive even when made into unwilling research assistants, continually listened to my issues and triumphs. My professors were invaluable: Professor Walker, with her unfailing patience, guided my writing and pointed out my small errors with the same gentle hand that showed where I had completely missed the point I was trying to make; Professor Koloski-Ostrow, always willing to give me a moment to answer yet another question I had; and my advisor, Professor Koh, who helped me transform what was just a paper into something much more...