On 12 August I have successfully passed my PhD viva. After two hours of intensive, but pleasant, questioning, my external committee consisting of Prof Wendy Bracewell and Dr Vladimir Unkovski Korica, agreed that I pass my Viva with minor corrections. Their comments, suggestions and criticism are the most useful for the final version.

I am very grateful to my supervisor Dr Bojan Aleksov for guiding me through the PhD process. It will be very sad to leave UCL, at least temporarily.

Wilkins Building 1 UCL London - Diliff