Funding for this research was provided by:
Norwegian Research Council (185209)
Article History
Received: 10 May 2017
Accepted: 20 July 2018
First Online: 25 July 2018
Compliance with ethical standards
:
: Jolien Vleeshouwers, Stein Knardahl and Jan Olav Christensen declare that they have no conflict of interest.
: 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.