Received: 27 August 2018
Accepted: 20 December 2018
First Online: 31 January 2019
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of the province Salzburg, which waived the requirement to obtain informed consent (IRB number: 415-EP/73/648–2016).
: Not applicable.
: The authors declare that they have no competing interests.
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