Funding for this research was provided by:
Eberhard Karls Universität Tübingen
Article History
Received: 26 July 2019
Revised: 13 December 2019
Accepted: 17 February 2020
First Online: 16 March 2020
Compliance with ethical standards
: The study was approved in advance by the local ethics committee, and participants gave their written consent at the beginning of the study.