................................................................................................................................... ii Declaration by author ............................................................................................................. v Publications during candidature .......................................................................................... vi Peer-reviewed publications ............................................................................................... vi Conference abstracts – oral presentations ......................................................................... vi Conference abstract – poster ............................................................................................ vii Publications included in this thesis ..................................................................................... viii Contributions by others to the thesis.................................................................................... ix Statement of contributions by others to the thesis as a whole ........................................... x Statement of parts of the thesis submitted to qualify for the award of another degree ... x Acknowledgements................................................................................................................. xi