Text and Data Mining valid from 2019-02-20
Received: 13 December 2018
Accepted: 9 January 2019
First Online: 20 February 2019
Compliance with ethical standards
: The authors declare that they have no conflicts 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. For this type of study formal consent is not required.
: Informed consent was obtained from all individual participant included in the study.