The rule is that a sample is safe when its radioactivity has dropped below detection limits. And that occurs at 10 half-lives. So, if radioactive iodine-131 (which has a half-life of 8 days) is injected into the body to treat thyroid cancer, itâll be âgoneâ in 10 half-lives, or 80 days.
The term 'ratchet' has no less than two distinct meanings. As an adjective, it describes a person, usually a woman, or activity, who is out of hand, out of control, generally whack in some way, dirty, ghetto, unattractive, Crucian, or just generally disliked.
ratchÂ·et 1. (rÄchâ²Ä­t) n. 1. A mechanism consisting of a pawl that engages the sloping teeth of a wheel or bar, permitting motion in one direction only. 2. The pawl, wheel, or bar of this mechanism. v. ratchÂ·etÂ·ed, ratchÂ·etÂ·ing, ratchÂ·ets.