Thesis by publication. Author has inserted citations for included papers. Ch.4 study 1, Ch. 4 study 2, Ch. 5 study 4, Ch. 6 study 5 permitted. All published versions have CC by licences. Ch.6 study 4 requires licence acknowledgment and link to published version via DOI. The citation included by author initially lists incorrect journal of publication. Additional citation page inserted. Sherpa/Romeo indicates permitted: https://v2.sherpa.ac.uk/id/publication/12687 https://v2.sherpa.ac.uk/id/publication/27918 https://v2.sherpa.ac.uk/id/publication/2477 Ch 5 study 3 not yet published. Paper which forms this chapter is a pre-print. The journal it has been submitted to has a licence agreement (https://www.biomedcentral.com/about/policies/license-agreement) which states "if editorially accepted for publication, shall be licensed under the Creative Commons Attribution License 4.0" indicating article can remain in the thesis. LM 07/07/2022