1. Department of Social Medicine; School of Public Health; Harbin Medical University; Harbin China
2. Department of Community Health Sciences; University of Calgary; Calgary Alberta Canada
3. Wenhua Community Clinics; Qiqihar China
4. The First Hospital of Qiqihar; Heilongjiang Province China
5. Department of Preventive Medicine; Medical School of Ningbo University; Ningbo Zhejiang Province China