Signature on PDF removed and full-text attachment replaced. LM 03/07/20 Thesis by publication. Papers which form chapters 3 &4 permitted as all 4 are Elsevier publications. Elsevier has a policy of allowing published articles to remain in theses.  https://www.elsevier.com/about/policies/copyright/permissions (click on Can I include/use my article in my thesis/dissertation). Paper which forms chapter 5 has not been published to date. LM 03/07/20