1. Department of Dermatology; Xijing Hospital; Fourth Military Medical University; Xi'an 710032 China
2. Department of Dermatology; the Second Hospital of Shanxi Medical University; Taiyuan 030001 China
3. Department of Surgery; Beckman Laser Institute and Medical Clinic; University of California; Irvine CA 92617 U.S.A.
4. Department of Biomedical Engineering; University of California; Irvine CA 92617 U.S.A.