1. University of Bern, Bern 3012, Switzerland
2. Federal Institute of Metrology METAS, Bern-Wabern 3003, Switzerland
3. University of Applied Sciences Northwestern Switzerland, Windisch 5210, Switzerland
4. University of Manchester, Manchester M13 9PL, United Kingdom
5. Finnish Meteorological Institute, Helsinki 00101, Finland
6. National Physical Laboratory, Teddington TW11 0LW, United Kingdom
7. Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas 66160, United States