continuous surface mirror
51Mathematics of radio engineering — A complex valued function. The mathematics of radio engineering is a pleasant and very useful subject. This article is an attempt to provide a reasonably comprehensive summary of this almost limitless topic. While the ideas have historically… …
52Global Positioning System — GPS redirects here. For other uses, see GPS (disambiguation). Geodesy Fundamentals …
53Sundial — A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style (a thin rod or a sharp, straight edge) onto a flat surface marked with lines indicating… …
54Dental caries — This article is about dental caries in humans. To read about dental caries in other animals, please see dental caries (non human). Dental caries Classification and external resources Destruction of a tooth by cervical decay from dental caries.… …
55Manifold — For other uses, see Manifold (disambiguation). The sphere (surface of a ball) is a two dimensional manifold since it can be represented by a collection of two dimensional maps. In mathematics (specifically in differential geometry and topology),… …
56china — /chuy neuh/, n. 1. a translucent ceramic material, biscuit fired at a high temperature, its glaze fired at a low temperature. 2. any porcelain ware. 3. plates, cups, saucers, etc., collectively. 4. figurines made of porcelain or ceramic material …
57China — /chuy neuh/, n. 1. People s Republic of, a country in E Asia. 1,221,591,778; 3,691,502 sq. mi. (9,560,990 sq. km). Cap.: Beijing. 2. Republic of. Also called Nationalist China. a republic consisting mainly of the island of Taiwan off the SE coast …
58digestive system, human — Introduction the system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract (alimentary canal), or the series of structures and organs through which food and liquids pass… …
59pre-Columbian civilizations — Introduction the aboriginal American Indian (Mesoamerican Indian) cultures that evolved in Meso America (part of Mexico and Central America) and the Andean region (western South America) prior to Spanish exploration and conquest in the 16th …
60technology, history of — Introduction the development over time of systematic techniques for making and doing things. The term technology, a combination of the Greek technē, “art, craft,” with logos, “word, speech,” meant in Greece a discourse on the arts, both… …
