Text and Data Mining valid from 2019-11-25
Received: 30 July 2019
Revised: 17 October 2019
Accepted: 21 October 2019
First Online: 25 November 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: Informed consent was obtained from all individual participants included in the study.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.