It was less than a week ago that we noted General Dynamics had landed a Pentagon contract to help tend to the bruised brains of troops suffering from Traumatic Brain Injury. We took note of it because we’ve seen big defense contractors increasingly move into the medical field in recent years. The latest evidence surfaced Tuesday, when Lockheed Martin, the nation’s biggest defense contractor, announced it had bought QTC Holdings Inc., which evaluates claims made by veterans seeking benefits from the Department of Veterans Affairs, among other military-medical missions. QTC is the largest company evaluating veterans’ claims for the VA; last year it handled nearly a half-million cases. Sales price was not disclosed.