U.S. Air Force Col. Bruce Cox, commander of the 307th Bomb Wing, at Barksdale Air Force Base, La, presides over the assumption of command ceremony where Col. Mark Nielsen takes command of the 307th Medical Squadron, April 12, 2015. Col. Nielsen is returning to the 307th Medical Squadron after a two year tour at the U.S. Air Force Academy as Individual Mobilization Augmentee to the United States Air Force Academy Command Surgeon and to the Commander of the 10th Medical Group. (U.S. Air Force photo by Master Sgt. Laura Siebert/Released)