1. Department of Sociology, University of Surrey, Guildford GU2 7XH, UK;
2. Department of Geography, University College London, London WC1E 6BT, UK;
3. Institute of Sociology and Social Psychology, University of Cologne, 50939 Cologne, Germany;
4. Centre for Demographic Studies, Autonomous University of Barcelona, Ca n’Altayo, Edifici E2, 08193, Bellaterra/Barcelona, Spain