1. Norwegian Institute of Urban and Regional Research, Oslo and Akershus University College of Applied Sciences, P.O. Box 4 St. Hanshaugen, N-0130, Oslo, Norway
2. Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, Norway
3. Department of Public Policy, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR
4. Institute of Chinese Borderland Research, Chinese Academy of Social Science, No. 10 Xianxiao HuTong, Dongcheng District, Beijing 100005, China