Text and Data Mining valid from 2017-01-09
Received: 20 August 2016
Accepted: 13 December 2016
First Online: 9 January 2017
Compliance with ethical standards
: On behalf of all authors, the corresponding author states that there is 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.