1. Urban and Regional Planning Department, San Jose State University, San Jose, CA 95192, USA
2. Department of Civil, Environmental, and Geomatic Engineering, University College London, Gower Street, London WC1E 6BT, England
3. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 11A Datun, Chaoyang, Beijing 100101, China
4. Department of Geography, University College London, Gower Street, London WC1E 6BT, England
5. Department of Geography and Environmental Management, University of the West of England, Coldharbour Lane, Bristol BS16 1QY, England