1. School of Nursing; Fourth Military Medical University; Xi'an Shaanxi Province China
2. National Institutes of Health; Clinical Center; Bethesda Maryland USA
3. Department of Nursing; First Hospital of Lanzhou University; Lanzhou Gansu Province China
4. Department of Epidemiology; Fourth Military Medical University; Xi'an Shaanxi Province China
5. Department of Orthopedic Surgery; Xijing Hospital; Fourth Military Medical University; Xi'an Shaanxi Province China
6. Institute of Mental Health; Peking University; Beijing China