- Correspondence to Dr Kevin L Winthrop, CEI/OHSU, 3375 SW Terwilliger Blvd, Portland, OR 97239, USA;
- Received January 16, 2015
- Revised July 2, 2015
- Accepted July 5, 2015
- First published August 28, 2015.
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- Data supplement 1 - Online supplement
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