Funding for this research was provided by:
Spanish Ministry of Education, Culture and Sport (CAST17/00072)
Text and Data Mining valid from 2019-01-18
Received: 8 March 2018
Accepted: 14 January 2019
First Online: 18 January 2019
Ethics approval and consent to participate
: Written informed consent was obtained from the parents or legal guardians of the students involved in the study. This study was conducted according to the guidelines laid down in the Declaration of Helsinki and was approved by the regional Ethics Committee for Medical Research Ethics Committee of The National University of Chimborazo (code: 46-CI-2015-07-02).
: Not applicable.
: The authors declare that they have no competing interests. In order to ensure transparency, we declare that the EV-G is a member of the Editorial Board of this journal.
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