This thesis is the result of many hours of work, and was made possible by generous contributions from a number of people.

The ideas and guidance of Professor R.O. Buchal were a valuable asset. Suggestions and feedback from fellow graduate students also aided in the work, in particular from Mr. Douglas Lee, and Mr. Peter Budgell. Valuable computer support by Mr. Dan Corrin made many tasks much easier. A thanks should be extended to all those who did not contribute directly, but enhanced the environment which made this work possible.

Finally, a thanks goes to Alicia, for her patience and understanding.