Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (01EE1409F)
Received: 20 November 2018
Accepted: 28 January 2019
First Online: 1 February 2019
Ethics approval and consent to participate
: The study protocol was reviewed and approved by the Commission for Impact Assessment Research and Ethics, Carl von Ossietzky University Oldenburg (reference number DRs. 23/2015); and by the concerned institutional ethic committees (Heidelberg University: reference number 2015–607 N-MA; Marburg University: reference number 148/15; Berlin University: reference number 941/15; Dresden University: reference number EK6012016). The data protection concept was additionally coordinated with the Data Protection Officer of the Carl von Ossietzky University, Oldenburg. All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.
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