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\section*{Acknowledgements}
\addcontentsline{toc}{chapter}{Acknowledgements}

This thesis would never have come into existence if my father had not
persuaded me to devote my PhD to gaining experience and insight into
`normal' physics research, at a time when I was inclined towards
dividing my efforts equally between physics, mathematics and
philosophy. It is therefore dedicated to him.  I am eternally grateful
for the moral support I have received from him and from my mother
throughout the 4 years I have spent on this work.

I wish to thank my supervisors Brian Pendleton and Richard Kenway for
their guidance and encouragement during my time here.  Special thanks
go to David Henty, with whom I worked both on the main projects in this
thesis, and who was always there to help when I got stuck.  Special
thanks also to Claudio Parrinello, who suggested and got me started on
the project which now comprises chapter~4, and who has given valuable
guidance up to the very end.  I would also like to thank David
Richards, who helped me when David and Claudio had left the department.

Thanks also to all those with whom I have shared offices, coffee breaks,
problems and frustrations during my years in the department, giving my
time within the walls of JCMB more than a bit of colour.

The financial support I received from the Norwegian Research Council the
first three years has been sufficient to keep me going the full four
years, and without that support this would never have seen the light of
day.

Finally, to all my friends in the Green Society and Green Student
Network, who have given me most of my life outside the department and a
purpose beyond just finishing a PhD.  My life would not have been a
tenth as interesting without all the gatherings, actions, gardening and
general social get-togethers with the rest of the `greenies'.  Thanks a
lot to you all!
