Aichmophobia Aichmophobia Aichmophobia () is a kind of specific phobia, the morbid fear of sharp things, such as pencils, needles, knives, a pointing finger, or even the sharp end of an umbrella and different sorts of protruding corners or sharp edges in furnitures and building constructions/materials. It is derived from the Greek "aichmē" (point) and "phobos" (fear). This fear may also be referred to as belonephobia or enetophobia. Sometimes this general term is used to refer to what is more specifically called fear of needles, or needle phobia. Fear of needles is the extreme and irrational fear of medical procedures involving
Irrational rotation Irrational rotation In the mathematical theory of dynamical systems, an irrational rotation is a map where "θ" is an irrational number. Under the identification of a circle with R/Z, or with the interval [0, 1] with the boundary points glued together, this map becomes a rotation of a circle by a proportion "θ" of a full revolution (i.e., an angle of 2"πθ" radians). Since "θ" is irrational, the rotation has infinite order in the circle group and the map "T" has no periodic orbits. Alternatively, we can use multiplicative notation for an irrational rotation by introducing the map The relationship