1 Senior Professorship on Work Stress Research, Life Science Centre, University of Düsseldorf, Merowingerplatz 1a, 40225 Düsseldorf, Germany. johannes.siegrist@med.uni-duesseldorf.de.
2 Institute of Occupational, Social and Environmental Medicine, Centre for Health and Society, Faculty of Medicine, University of Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany. jian.li@uni-duesseldorf.de.