Cryogenics necessary to use a silicon diode for accuracy. Cryogenics In physics, cryogenics is the production and behaviour of materials at very low temperatures. A person who studies elements that have been subjected to extremely cold temperatures is called a "cryogenicist". It is not well-defined at what point on the temperature scale refrigeration ends and cryogenics begins, but scientists assume a gas to be cryogenic if it can be liquefied at or below . The U.S. National Institute of Standards and Technology has chosen to consider the field of cryogenics as that involving temperatures below . This is a logical dividing
Prefix order Prefix order In mathematics, especially order theory, a prefix ordered set generalizes the intuitive concept of a tree by introducing the possibility of continuous progress and continuous branching. Natural prefix orders often occur when considering dynamical systems as a set of functions from "time" (a totally ordered set) to some phase space. In this case, the elements of the set are usually referred to as "executions" of the system. The name "prefix order" stems from the prefix order on words, which is a special kind of substring relation and, because of its discrete character, a tree. A prefix order is