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I owe a debt of gratitude to many people for their help and support during the preparation of this thesis.
I am deeply grateful to my two supervisors, Professor Dáithí Ó hÓgáin and Professor Neil Davie, who have been extremely helpful, offering invaluable assistance, encouragement and guidance. Without their constant support and stimulating suggestions, this research would not have been possible. Thanks is also due to Pierre-Yves Lambert and Matthieu Poux for their valuable suggestions and their constructive comments. I am grateful that, in the midst of all their other commitments, they agreed to be members of the dissertation committee.
I also wish to express my gratitude to my parents, for their understanding and endless love, throughout my studies.