I would like to express my sincere gratitude to God for the wisdom and perseverance He has bestowed upon me during this research project and throughout my life. The success of this work was a result of the valuable help from various persons. First, is Dr. H. Mvula from University of Malawi for his spiritual and constant encouragement to complete the work. His supervision and thorough analysis of my work consequently widened my scope of scholarship. Lastly, I would like to thank my parents, siblings, my daughter and friends for the emotional and financial support during this course.