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Article History

Received: 23 January 2019

Accepted: 30 May 2019

First Online: 22 June 2019

Ethics approval and consent to participate

: All subjects gave their informed consent to participate after agreeing to the purpose, method and importance of the study. The study conformed to the Declaration of Helsinki guidelines and was approved by the ethics Committee of Hiroshima University (H24–27 and H25–29).

: This manuscript does not contain any individual person’s data; we agree to the disclosure.

: The authors declare that they have no competing interests.

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