Text and Data Mining valid from 2018-05-29
Received: 7 February 2018
Accepted: 15 May 2018
First Online: 29 May 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.