An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Kristensen TN, Hoffmann AA, Overgaard J, Sørensen JG, Hallas R, Loeschcke V.Kristensen TN, et al.Proc Natl Acad Sci U S A. 2008 Jan 8;105(1):216-21. doi: 10.1073/pnas.0708074105. Epub 2007 Dec 27.Proc Natl Acad Sci U S A. 2008.PMID: 18162547Free PMC article.