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Ashby FG, Maddox WT.Ashby FG, et al.Ann N Y Acad Sci. 2011 Apr;1224:147-161. doi: 10.1111/j.1749-6632.2010.05874.x. Epub 2010 Dec 23.Ann N Y Acad Sci. 2011.PMID: 21182535Free PMC article.Review.