Funding for this research was provided by:
Ministry of Science, Research and Arts, state of Baden-Wuerttemberg, Germany
Article History
Received: 18 May 2017
Accepted: 15 February 2018
First Online: 21 February 2018
Ethics approval and consent to participate
: The study was approved by the ethical committee of Ulm University (application no. 318/08). All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.
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