Text and Data Mining valid from 2018-03-15
Received: 2 March 2018
Accepted: 6 March 2018
First Online: 15 March 2018
Compliance with ethical standards
: The authors declare that they have no competing interests.
: 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.