Funding for this research was provided by:
Velux Fonden (# 000121540)
Received: 7 November 2018
Accepted: 24 January 2019
First Online: 8 February 2019
Ethics approval and consent to participate
: Ethics permission for the study protocol was obtained from the Multi-Centre Research Ethics Committee for Scotland (MREC/01/0/56) and from Lothian Research Ethics Committee (LREC/2003/2/29).
: Written consent was obtained for all authors.
: The authors declare that they have no competing interests.
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