1 Institute and Policlinic for Occupational Medicine, Environmental Medicine and Prevention Research, Uniklinik Köln, University of Cologne, Cologne, Germany. Electronic address: tim.erren@uni-koeln.de.
2 Institute and Policlinic for Occupational Medicine, Environmental Medicine and Prevention Research, Uniklinik Köln, University of Cologne, Cologne, Germany.
3 Institute of Geophysics and Meteorology, University of Cologne, 50923, Köln, Germany.
4 Research Institute of Luminous Organisms, Hachijojima, Tokyo, Japan.