6 month embargo approved 3 December 2015 -MA 15/3/16. Full-text added MA 19/7/16. ------ Thesis by publication. Paper which forms chapter 2 is a pre-print, and the article was not published at the time the thesis was added. Permissions at https://academic.oup.com/journals/pages/access_purchase/rights_and_permissions/self_archiving_policy_b require that the published version be acknowledge. A note to this fact has been added to thesis. Papers which form chapters 3, 4a, 4b, and 6 are permitted, and the author has included copyright agreements for each. Paper which forms chapter 5 was never published. It wasn't realised at the time of metadata record creation that this was a thesis by publication. Copyright permissions not checked at that time. Original thesis suppressed 08/03/19 after removing signatures, and copyright note added. The complete thesis is available in the Y drive. LM 08/03/19