Airman 1st Class Daniel Phelps, 779th Medical Group medical laboratory technician, prepares to perform a cross match on blood on Jan. 31, 2013 at Joint Base Andrews, Md. The transfusions are used to replace lost blood during a surgery and supplement for patients who are not able to properly produce their own blood. (U.S. Air Force photo/Airman 1st Class Erin O’Shea)