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.
There are technically no specific age requirements for soldiers seeking to become Army Rangers. Thus, the effective age limits are the same as those required to join the Army in the first place. Applicants must be at least 17 years old (or 18 without parental permission) and no older than 41 years old.he Rangers do not put an age limit on officers looking to join the regiment. However, they must be ranked between first lieutenant and major (O-2 to O-4). This means newly commissioned officers are not eligible to join, while officers ranked O-5 and above are no longer able to apply.