The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

beam

1. A unidirectional, or approximately unidirectional emission of electromagnetic radiation or particles.

2. Any slender structure of a denture or orthodontic appliance designed to provide support to the structure and subjected to lateral stresses, such as a dental bar or an orthodontic arch wire whose curvature changes under load.

3. A large long piece of timber or metal.

4. The bar of a balance from which the scales hang.

5. The breadth of a ship at its widest part.

6. A ray or shaft of light.

7. A constant radio signal transmitted for the guidance of pilots; also, the course indicated by this signal.

8. To send out light.

9. To aim (a broadcast) by directional antennas.

10. To smile with joy.