Text and Data Mining valid from 2019-07-13
Received: 31 March 2019
Accepted: 1 July 2019
First Online: 13 July 2019
Compliance with ethical standards
: The authors declare no potential conflicts of interest with respect to the authorship, and/or publication of this article.
: All procedures performed 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.
: Written informed consent obtained from the guardians of all participants.