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. 2018 Feb 13;18:41. doi: 10.1186/s12886-018-0705-6

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© The Author(s). 2018

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Fig. 1 — Map of China. The map picture was created by the user “Quigley” under the Creative Code “CC BY-SA 3.0” at the wiki website of https://en.wikipedia.org/wiki/Xinjiang. It has been credited and edited with study sites being marked