Text and Data Mining valid from 2019-05-29
Received: 2 April 2019
Accepted: 18 May 2019
First Online: 29 May 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This research was performed 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.