primary x-rays
91dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …
92X-ray crystallography — can locate every atom in a zeolite, an aluminosilicate with many important applications, such as water purification. X ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X rays strikes a… …
93Tampa, Florida — Tampa redirects here. For other uses, see Tampa (disambiguation). Tampa   City   Images from top, left to right: Skyline of D …
94Cassegrain reflector — The Cassegrain reflector is a combination of two coaxial reflectors used in Cassegrain telescopes and radio antennas.First developed in 1672 by Laurent Cassegrain, this reflector is a combination of a primary concave mirror and a secondary convex …
95electromagnetic radiation — Physics. radiation consisting of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, x rays, and gamma rays. [1950 55] * * * Energy propagated through free space or through a material medium in the form of… …
96chemical element — Introduction also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed. This article considers the… …
97isotope — isotopic /uy seuh top ik/, adj. isotopically, adv. /uy seuh tohp /, n. Chem. any of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number, but having different numbers of neutrons in… …
98photoreception — photoreceptive, adj. /foh toh ri sep sheuhn/, n. the physiological perception of light. [1905 10; PHOTO + RECEPTION] * * * Biological responses to stimulation by light, most often referring to the mechanism of vision. In one celled organisms such …
99Nobel Prizes — ▪ 2009 Introduction Prize for Peace The 2008 Nobel Prize for Peace was awarded to Martti Ahtisaari, former president (1994–2000) of Finland, for his work over more than 30 years in settling international disputes, many involving ethnic,… …
100Chiropractic — Intervention A chiropract …
