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Article History

Received: 21 May 2017

Accepted: 25 March 2018

First Online: 3 April 2018

Ethics approval and consent to participate

: We obtained ethical approval as appropriate to each country, e.g. Ethics Commission of the Charité Universitätsmedizin; reference number EA2/069/13. We obtained written informed consent from all participants and if the participant was underage, both the participants and the parents in cases of young people below age 18 gave written informed consent.

: Not applicable.

: All authors declare no support from any organization for the submitted work; no relationship with any organization that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work. Therefore, the authors declare that they have no competing interests.

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