Text and Data Mining valid from 2018-08-28
Received: 26 June 2018
Accepted: 13 August 2018
First Online: 28 August 2018
Ethics approval and consent to participate
: This study was approved by the institutional review board of Jichi Medical University (Tochigi, Japan; 16-120). Written informed consent was obtained from all participants or their nearest relatives.
: Not applicable.
: The authors declare that they have no competing interests.
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