The Acknowledgements provides the author with the opportunity to express his sincere gratitude to those who have offered academic assistance, resources and moral support. Put the following disordered Acknowledgements into a logical one.A In particular I would like to thank Michael White for the suggestions he made in reference to Chapter 4 of this work.B I would also like to thank the Engineering and Physical Sciences Research Council, not only for providing the funding which allowed me to undertake this research, but also for giving me the opportunity to attend conferences and meet so many interesting people.C I would like to express my deepest gratitude to my supervisor, Prof. Nicholas Young, for the patient guidance, encouragement and advice he has provided throughout my time as his student.D Finally, I must express my gratitude to Karina, my wife, for her continued support and encouragement. E I have been extremely lucky to have a supervisor who cared so much about my work, and who responded to my questions and queries so promptly.F Besides my supervisor, I am grateful to all the members of staff at Newcastle and Lancaster Universities who helped me in my supervisor’s absence.G I was continually amazed by her willingness to proof read countless pages of meaningless mathematics, and by the patience of my mother, father and brother who experienced all of the ups and downs of my research._____-_____-_____-_____-_____-_____-_____