Funding for this research was provided by:
German Federal Chancellery (VwV120516)
Received: 21 August 2017
Accepted: 28 December 2017
First Online: 1 February 2018
Ethics approval and consent to participate
: All project partners sought ethical approval within their institution of reference — university or region, depending on the regional law — and obtained it (reference numbers are Berlin: EA1/117/16, Nuremberg: 016/1511, Rostock: A2016-0142, Frankfurt a. M.: 334/16, Mainz: 837.316.16 (10635)).
: Not applicable
: The authors declare that they have no competing interests.
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