In 1905, Levene was appointed as head of the biochemical laboratory at the Rockefeller Institute of Medical Research. He spent the rest of his career at this institute, and it was there that he identified the components of DNA.
It also takes anywhere from 18 to 24 months to get promoted to O-2 following entry to the Army, so the effective minimum age to join the Rangers for officers is around 23 to 24 years old. Officers can then continue to apply until they are promoted to O-5.
Body Fat Percentage. Army Rangers, as well as other soldiers, can vary from the height and weight charts if their body fat still meets the requirements. In general, soldiers must maintain no more than 20 percent body fat in the 17 to 20 age range and 22 percent if they are ages 21 to 27.