Text and Data Mining valid from 2018-06-19
Received: 30 March 2018
Accepted: 29 May 2018
First Online: 19 June 2018
: The authors declare that they have no competing interests.
: This study was approved by the Institutional Ethics Committee at the University of Occupational and Environmental Health in 2013 (H25-008) and Kagoshima University Graduate School of Medical and Dental Sciences in 2014 (486).
: Written informed consents were obtained from all participants.
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