Text and Data Mining valid from 2019-02-12
Received: 11 October 2018
Revised: 7 January 2019
Accepted: 28 January 2019
First Online: 12 February 2019
Compliance with ethical standards
: The 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. The study described has been carried out in accordance with the abovementioned standards and has been approved by the institutional ethic committee.
: Informed consent was obtained from all individual participants included in the study.