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dissertation would not have been possible without the guidance and the support of several individuals who contributed and extended their valuable assistance in the completion of this study. First, I would like to thanks my parents and my sister who encouraged me a lot during the course of my study. I appreciate their sacrifice, support, and understanding without which my graduation would not have been feasible. Second, it would not be easy for me to find enough words to thank Tomek, my advisor, for having the belief in me and for his continuous support and motivation. He has inflamed my desire to love what I’m doing and to be more creative and successful in the scientific and in the personal manner. He motivated me and helped me to overcome many cultural obstacles that I was facing without which I will not be able to concentrate and succeed. He wasn’t only a great advisor for us; he was also a friend to us. My sincere thanks go to my best friends in Saudi Arabia, Sara, Hana, and also to Noran, and Reem for being such wonderful friends who has been extremely supportive and always there for me. I can’t be thankful enough to Sandeep for being my best friend and for his support.