Crystal Hogg (left) adjusts the IV tube on Senior Airman Brandon Williams' arm while he donates red blood cells at an Oklahoma Blood Institute mobile blood drive at Tinker Air Force Base, Okla., on July 20, 2011. The blood goes to an apheresis machine, which separates red blood cells from his blood, then returns the plasma and platelets back to his body. (U.S. Air Force photo by Tech. Sgt. Zach Jacobs)