Text and Data Mining valid from 2018-06-07
Received: 24 January 2018
Accepted: 25 May 2018
First Online: 7 June 2018
Compliance with ethical standards
: Conflict of interest.
: The authors declare that they have no conflict of interest.
: Ethical approval
: 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
: Informed consent was obtained from all individual participants included in the study.