Text and Data Mining valid from 2018-03-03
Received: 16 November 2017
Accepted: 21 February 2018
First Online: 3 March 2018
Compliance with ethical standards
: All 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.
: Informed consent was obtained from all individual participants included in the study.