Funding for this research was provided by:
Deutsche Forschungsgemeinschaft (Ku 1964/6-3)
Article History
Received: 27 November 2017
Accepted: 16 April 2018
First Online: 20 April 2018
Compliance with ethical standards
:
: All authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.