Text and Data Mining valid from 2018-05-30
Received: 19 March 2018
Accepted: 24 May 2018
First Online: 30 May 2018
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This article does not contain any studies with animals performed by any of the authors. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and 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.