Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (01GL1706A, 01GL1760C, 01GL1706B)
Received: 18 October 2018
Accepted: 26 April 2019
First Online: 29 May 2019
Ethics approval and consent to participate
: Ethical approval was granted by the ethics committees of Martin Luther University of Halle-Wittenberg in June 2018 (2018–63) and Ludwig Maximilian University of Munich in July 2018 (18–356). Each participant must sign a written informed consent form prior to enrolment. Approval for the informed consent materials was received from both ethics committees.
: Not applicable.
: The authors declare that they have no competing interests.
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