Acetylcholine is an organic chemical that functions in the brain and body of many types of animals, including humans, as a neurotransmitterâa chemical released by nerve cells to send signals to other cells. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Parts in the body that use or are affected by acetylcholine are referred to as cholinergic. Substances that interfere with acetylcholine activity are called anticholinergics. Acetylcholine is the ...
Every interior algebra can be represented as a topological field of sets with its interior and closure operators corresponding to those of the topological space. Given a topological space the clopen sets trivially form a topological field of sets as each clopen set is its own interior and closure.
foundations of mathematics. ...1, where 0 is the empty set and 1 is the set consisting of 0 alone. Both definitions require an extralogical axiom to make them workâthe axiom of infinity, which postulates the existence of an infinite set. Since the simplest infinite set is the set of natural numbers, one cannot really say that arithmetic has been reduced to logic.