Text and Data Mining valid from 2019-08-31
Received: 22 April 2019
Accepted: 21 August 2019
First Online: 31 August 2019
Compliance with ethical standards
: The authors declare that they have no conflicts of interest.
: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.
: 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.