All praises be to "Almighty Allah" the lord of the world, the most beneficent and merciful and peace be upon his Prophet Mohammed (SAWS). Through the grace of Almighty Allah, the uphill task on my shoulder has been accomplished. The completion of this dissertation is not only fulfillment of my dreams but also of my parents who have sacrificed a lot for me in completion of this course. The writing of a dissertation is obviously not possible without the support and company of numerous people. It is a pleasant aspect that I have now the opportunity to express my gratitude...