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.
Average age during World War 2 was 26 years. 3 The infantry soldier in the South Pacific in WW2 saw about 40 days of combat in four years. 4 The American infantry soldier in Vietnam saw about 240 days of combat in 1 year. 5 The Australian infantry soldier saw an average of 314 days combat in 1 year.