['Whereas', 'photo', '-', 'radiation', 'causes', 'DSBs', 'through', 'two', 'step', 'mechanism', '(', 'Figure', '3a', ')', 'by', 'reflecting', 'that', 'each', 'single', 'photon', 'causes', 'mostly', 'single', 'ROS', 'and', 'thus', 'induces', 'only', 'single', 'strand', 'break', '.']