Funding for this research was provided by:
the Japan Ministry of Education, Culture, Sports, Science and Technology (17390197)
Article History
Received: 13 August 2018
Accepted: 8 October 2018
First Online: 24 October 2018
Ethics approval and consent to participate
: This study was approved by the Ethical Committee for Human Research at the Osaka Institute of Public Health located in Osaka (0903-02). The study was completed in accordance with the Helsinki Declaration.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.