1. College of Computer Science, Sichuan University, Chengdu, China
2. Department of Computing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
3. College of Computer Science, Chongqing University, Chongqing, China
4. Key Laboratory of Birth Defects and Related Maternal and Child Diseases, theWest China Second Hospital, and the College of Computer Science, Sichuan University, Chengdu, Sichuan, China
5. Department of Computer Science, City University of Hong Kong, Hong Kong, China
6. College of Computer Science and Technology, Zhejiang University of Technology, Hangzhou, China
7. Department of Computer Science, Missouri University of Science and Technology, Rolla, MO, USA