Contribution to authorship
J.H.Y. Q. Z. and T.X.N. supervised the entire study, including the
conception, design, procedures and completion. L.L.Y., T.X.N., Y.Y.Y.
and M.D.X. took the responsibility for the collection of data. L.L.Y.
and T.X.N. were responsible for the data analysis and first draft of
article. J.H.Y. T.X.N. and M.D.X. participated in the interpretation of
the study data and in revisions to the article. All authors reviewed and
approved the final version of this work.