From the bottom of my heart, I express my gratefulness to the following people for their contribution in this thesis: Professor IEM Coetzee, who guided me throughout this study unselfishly, encouraged and supported me patiently and excellently with her expertise. Professor CJ White, for laying the foundation for me as a student researcher. My family members, my daughter Amogelang Ofentse Maake who is my inspiration and a reason to hang on to dear life. My mother Moipone for her continuous and tireless parental care up to date, my wife and partner in studies, Kelebogile for prompting me to study further. My elder brother, Melato (br. Chalie) for being my bosom friend which kept me going during stormy weathers and Lephai, my younger brother, ...