Opportunities and challenges to non-communicable disease (NCD) research and training in Pakistan: a qualitative study from Pakistan oleh Sameen Siddiqi, Zulfiqar Ahmed Bhutta, Tazeen H Jafar, Pamela Douglas, Muhammad Imran Nisar, John Bartlett, Safia Awan, Zainab Samad, Aysha Almas, Asad Ali, Asma Ahmed, Gerald Bloomfield, Saad Hameed Shafqat, Daniel Benjamin Mark