Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (BMBF 01EO1303)
Received: 13 March 2017
Accepted: 12 February 2018
First Online: 20 February 2018
Ethics approval and consent to participate
: The study protocol was approved by community officials and the Ethics Committee of the University of Freiburg (Ref. No. 258/11_120365). Written informed consent was obtained from all individual participants included in the study.
: No individual details or images are included in the present study. Consent to publish in not required.
: The authors declare that they have no competing interests.
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