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fluorescence

(Encyclopedia)fluorescence flo͝orĕsˈəns [key], luminescence in which light of a visible color is emitted from a substance under stimulation or excitation by light or other forms of electromagnetic radiation or ...

sapodilla

(Encyclopedia)sapodilla, the edible fruit of Manilkara zapota (formerly Achras zapota), of the family Sapotaceae. The fleshy, brown fruit is the size of a small tomato, and has the flavor and texture of cinnamon, a...

happening

(Encyclopedia)happening, an artistic event of a theatrical nature, but usually improvised spontaneously without the framework of a plot. The term originated with the creation and performance in 1959 of Allan Kaprow...

Warner, Seth

(Encyclopedia)Warner, Seth, 1743–84, hero of the American Revolution, b. Roxbury, Conn. One of the group who, under Ethan Allen, resisted the New York claim to the New Hampshire Grants (now Vermont), he was outla...

gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...

angstrom

(Encyclopedia)angstrom ăngˈstrəm [key], abbr. Å, unit of length equal to 10−10 meter (0.0000000001 meter); it is used to measure the wavelengths of visible light and of other forms of electromagnetic radiatio...

polonium

(Encyclopedia)polonium pəlōˈnēəm [key], radioactive chemical element; symbol Po; at. no. 84; mass no. of most stable isotope 209; m.p. 254℃; b.p. 962℃; sp. gr. about 9.4; valence +2 or +4. Polonium is an e...

fog

(Encyclopedia)fog, aggregation of water droplets or ice crystals immediately above the surface of the earth (i.e., a cloud near the ground). A light or thin fog is usually called a mist. Fog may occur when the mois...

Ashkin, Arthur

(Encyclopedia)Ashkin, Arthur, 1922–2020, American physicist, b. Brooklyn, N.Y., Ph.D. Cornell, 1952. Ashkin worked for four decades at Bell Laboratories, retiring in 1992. Ashkin researched microwaves, nonlinear ...

Mössbauer, Rudolf Ludwig

(Encyclopedia)Mössbauer, Rudolf Ludwig, 1929–2011, German physicist, Ph.D. Max Planck Institute for Medical Research, Heidelberg, Germany, 1957. Mössbauer was a professor at the California Institute of Technolo...