Probiotics such as bifidobacteria are typically used in cases when a disease occurs or might occur due to a kill-off of normal bacteria. For example, treatment with antibiotics can destroy disease-causing bacteria, but also normal bacteria in the GI (gastrointestinal) and urinary tracts.
The 3-place Hiller Model 360, military H-23 Raven, was based on the U.S. Navy UH-12, which was first flown in 1948. The H-23 Raven performed as a utility, observation, and MedEvac helicopter during the Korean war.
During the Vietnam War, the use of the helicopter, known as Air Mobile, was an essential tool for conducting the war. In fact, the whole conduct and strategy of the war depended on it. Vietnam was the first time the helicopter was used on a major scale, and in such important roles.