Text and Data Mining valid from 2016-02-09
Received: 13 October 2015
Accepted: 22 January 2016
First Online: 9 February 2016
Compliance with ethical standards
: The research was approved by the Ethic in Research Committee from the Federal University of Rio Grande do Norte and 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 in writing was obtained from all individual participants included in the study.
: On behalf of all authors, the corresponding author states that there is no conflict of interest.