Text and Data Mining valid from 2018-03-01
Received: 22 April 2016
Revised: 4 August 2017
Accepted: 16 February 2018
First Online: 1 March 2018
Compliance with Ethical Standards
: The authors report no conflicts of interest.
: All procedures performed in the study 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.