1. School of Information Science and Technology, Guangdong University of Foreign Studies, Guangzhou, Guangdong, China
2. School of Computer Science and Technology, Guangdong University of Technology, Guangzhou, Guangdong, China
3. Institute of Health Informatics, University College London, London, U.K.
4. Guangzhou Key Laboratory of Multilingual Intelligent Processing, and the School of Information Science and Technology, Guangdong University of Foreign Studies, Guangzhou, Guangdong, China