A cross-section of skeletal muscle in this light micrograph shows the individual, parallel muscle fibers (red). These fibers work in concert to power movement. Thomas Deerinck, NCMIR/ScienceSource hide caption

itoggle caption Thomas Deerinck, NCMIR/ScienceSource

Remembrance poppies honoring veterans cover a shrine in Wellington, New Zealand, on a recent April 25, when Australia and New Zealand mark ANZAC Day. A new campaign urges people to buy a minute of silence to support veterans. Hagen Hopkins/Getty Images hide caption

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A crowd gathers at the World War II Memorial to call for reopening national memorials closed by the government shutdown. The rally drew support from military veterans, Tea Party activists and Republicans. Andrew Burton/Getty Images hide caption

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After a photo of Lanny Martinson's dog tag was placed on Facebook and elsewhere, Marines and veterans helped track him down. Martinson lost the tag in Vietnam in 1968. Facebook hide caption

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Women's Correctional Community Center inmate Lilian Hussein checks on ti leaves she planted as part of the prison's farming and gardening program in Kailua, Hawaii. The green ti leaves are often used to wrap food or weave into leis. Jennifer Sinco Kelleher/AP hide caption

itoggle caption Jennifer Sinco Kelleher/AP

April 20: Soldiers from the U.S. Army 3rd Infantry Regiment, also called "The Old Guard," carry U.S. Army Corporal Justin Ross' flag-draped casket during his burial ceremony at Arlington National Cemetery. Ross, 22, of Green Bay, Wis., died March 26 in Helmand province, Afghanistan. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images