First Manamanni who spared their precious time to

First  of  all,  thanks  to  Almighty  Allah  for  granting  me  the  courage,  knowledge, determination  and  environment  to  continue  my  research  work.  I  also  pay  all  the tributes  to  the  Prophet  Muhammad  (Peace  be  Upon  Him),  for  enlightening  our conscience, who’s love is the real success of life. I  am  especially  thankful  to  my  mother  and  my  spouse  for  their  continuous  support, encouragement and patience during my doctoral studies. I  am  very  grateful  to  my  supervisor  Dr.  Aamer  Iqbal  Bhatti  and  co-supervisor  Dr. Muddassar Abbas Rizvi for all their support, guidance and discussions in finding the right  research  direction. I  owe  thanks  to  my  supervisor  Dr.  Aamer  Iqbal  Bhatti  for  his scholarly guidance, encouragement and valuable suggestions that enable me to follow the right track during my research work. I am indebted to Dr. Muddassar for his attention, guidance  and  encouragement  in  the  present  work.  He was  always  available  for discussion  and  help  on  different  issues  faced  during  this  work. It  is  his  consistent scholarly guidance that made successful completion of this work possible. I  am  thankful  to  Dr.  Kamran  Iqbal  and  Dr.  Noureddine  Manamanni  who  spared  their precious  time  to  review  this  research  work  and  provided  the  valuable  comments  for  its improvement. I  am  also  thankful  to  all  members  of  CASPR  for  their  valuable  suggestions  and support.  It  is  really  a  blessing  to  have  company  of  so  supporting  and  competent people around me who helped me out of problems I faced in this research work. I am also  thankful  to  my  colleague  and  friend  Dr.  Faisal  Nadeem  for  his  help  in  the proofreading of this thesis. Special  thanks  are  due  to  my  parent  organization  PINSTECH  for  facilitating  my studies with study leave and to HEC for funding my doctoral studies at this institute