Funding for this research was provided by:
Ministry of Education and Science of the Republic of Kazakhstan (№ 1080/ГФ4)
Received: 22 September 2017
Accepted: 5 January 2018
First Online: 12 January 2018
Ethics approval and consent to participate
: Approval for the study obtained from the local institutional ethics committee and informed consent obtained from all study participants.
: Not applicable.
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