Text and Data Mining valid from 2016-12-30
Received: 8 September 2016
Accepted: 16 December 2016
First Online: 30 December 2016
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.