Text and Data Mining valid from 2019-02-13
Received: 4 December 2018
Accepted: 11 January 2019
First Online: 13 February 2019
Compliance with ethical standards
: The authors declare no potential conflicts of interests associated with this study.
: 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.