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iii Acknowledgements This work would not have been possible without the help and support of numerous people that have guided me through various phases of graduate school. I am very grateful to them and would like to thank them from bottom of my heart. First and foremost, I would like to express my deep gratitude to my advisor Dr. David Williams for his unparalleled support and guidance. This piece of work would not have been accomplished without his knowledge, insight and wisdom. He has been a great role model and I have learned valuable lessons from him that have given me the right attitude to pursue a career in science. I am thankful for his patience and support through all the ups and downs faced during this journey