1. Department of Geography, Michigan State University, East Lansing, MI 48824, USA
2. Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA
3. MRC/CSO Social and Public Health Sciences, University of Glasgow, Glasgow G12 8QQ, UK
4. Department of Kinesiology, Michigan State University, East Lansing, MI 48824, USA
5. Department of Kinesiology and Health Science, Utah State University, Logan, UT 84322, USA