RADIUS(redirected from radii)
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arm, upper limb in humans. Three long bones form the framework of the arm: the humerus of the upper arm, and the radius (outer bone) and ulna (inner bone) of the forearm. The radius and ulna run parallel but meet at their ends in such a manner that the radius can rotate around the ulna. This arrangement permits turning the forearm to bring the hand palm up (supination) or palm down (pronation). The radius and ulna hinge with the bones of the hand at the wrist, and with the humerus at the elbow. The biceps brachii, a muscle of the upper arm, bends the arm at the elbow; the triceps brachii straightens the arm. Movement of the arm across the chest and above the head is accomplished by the pectoral muscles of the chest and deltoid muscles of the shoulder, respectively. In an adult the arm is normally five sixths as long as the leg.
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The outer of the two bones of the human forearm or of the corresponding part in vertebrates other than fish.
A line segment joining the center and a point of a circle or sphere.
The length of such a line segment.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
1. a straight line joining the centre of a circle or sphere to any point on the circumference or surface
2. the length of this line, usually denoted by the symbol r
3. the distance from the centre of a regular polygon to a vertex (long radius) or the perpendicular distance to a side (short radius)
4. Anatomy the outer and slightly shorter of the two bones of the human forearm, extending from the elbow to the wrist
5. a corresponding bone in other vertebrates
6. any of the veins of an insect's wing
7. a group of ray florets, occurring in such plants as the daisy
8. the lateral displacement of a cam or eccentric wheel
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
Remote Authentication Dial-In User Service
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)
RADIUS(Remote Authentication Dial-In User Service) An authentication, authorization and accounting (AAA) protocol developed by Livingston Enterprises (later acquired by Lucent). RADIUS uses a challenge/response method for authentication and has been widely used prior to Diameter. See Diameter, network access server and challenge/response.
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