Funding for this research was provided by:
National Institute on Drug Abuse (1DP1DA039542)
Estonian Ministry of Education and Research (IUT34-17)
Article History
Received: 22 January 2018
Accepted: 21 February 2018
First Online: 5 March 2018
Ethics approval and consent to participate
: Ethical approvals were obtained from the Tallinn Medical Research Ethics Committee (2007) and Ethics Review Board of the University of Tartu (2009–2013) and the Beth Israel Medical Center Institutional Review Board for 2007–2013 in New York, USA. Written informed consent was secured from all participants.
: Not applicable
: The authors declare that they have no competing interests.
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