I hereby declare that this thesis is composed of my original work and that, to the best of my knowledge and belief, it reproduces no material previously published or written nor material which has been accepted for the award of any other degree or diploma, except where due acknowledgment has been made in the text. I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, and any other original research work used or reported in my thesis. I have clearly stated which parts of my thesis, if any, have been submitted to qualify for another award.