Alexander Krämer is Professor of Public Health Medicine and a cofounder of the School of Public Health at Bielefeld University, where he has been active since 1994. During 1992-1994 he was a Visiting Assistant Professor at the Division of Epidemiology, University of Minnesota, USA. His background is in medicine, epidemiology and public health, with main research interests in infectious diseases and urban health. Mobarak Hossain Khan is Assistant Professor at the Department of Public Health Medicine at Bielefeld University since early 2007. He obtained his M.Sc. in statistics in 1990 from Jahangirnagar University, Bangladesh, and M.Sc. in Community Health and Health Management from… Heidelberg University in 2000. In 2007 he received his Ph.D. in Public Health from Sapporo Medical University, Japan.Frauke Kraas is Professor and Chair of Human Geography at the University of Cologne since 2000. She holds a PhD (1991) and a Habilitation (1996) in Geography from the Universities of Münster and Bonn where she worked as Research Fellow and Assistant Professor from 1987 to 2000. She was awarded the Gerhard-Hess-Price (1997) and the Heisenberg Postgraduate Scholarship (1998) from the German Research Council (DFG).