aDepartment of Epidemiology and Biostatistics, School of Public Health, Jilin University, Changchun, China
bApplied Research/Psychiatry, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
*Xiangfei Meng and Changgui Kou contributed equally to the writing of this article.
Correspondence to Xiangfei Meng, PhD, Applied Research/Psychiatry, University of Saskatchewan, Box 92 RUH, 103 Hospital Drive, Saskatoon, SK, Canada S7N 0W8Tel: +1 306 966 8772; fax:+1 306 966 8774; e-mail: email@example.com
Received August 2, 2011
Accepted February 27, 2012