Staff Sgt. Carleen Wallance (left), 374th Medical Group, and Staff Sgt. Zachary Burtt, 374th Security Forces Squadron, check a victim's vital signs at Yokota Air Base, Japan, May 24, 2010, during a simulated mass casualty event during an operational readiness exercise. Yokota is conducting an exercise through May 27, 2010, to maintain operational readiness. (U.S. Air Force photo/Osakabe Yasuo)