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81UNITED STATES OF AMERICA — UNITED STATES OF AMERICA, country in N. America. This article is arranged according to the following outline: introduction Colonial Era, 1654–1776 Early National Period, 1776–1820 German Jewish Period, 1820–1880 East European Jewish Period,… …
82X-ray fluorescence — (XRF) is the emission of characteristic secondary (or fluorescent) X rays from a material that has been excited by bombarding with high energy X rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis,… …
83Structure formation — refers to a fundamental problem in physical cosmology. The universe, as is now known from observations of the cosmic microwave background radiation, began in a hot, dense, nearly uniform state approximately 13.7 Gyr ago. [cite journal |author=D.… …
84Physical Sciences — ▪ 2009 Introduction Scientists discovered a new family of superconducting materials and obtained unique images of individual hydrogen atoms and of a multiple exoplanet system. Europe completed the Large Hadron Collider, and China and India took… …
85Sound masking — For other uses of masking , see Masking (disambiguation). Sound masking is the addition of natural or artificial sound (such as as white noise or pink noise) into an environment to cover up unwanted sound by using auditory masking. This is in… …
86astronomy — /euh stron euh mee/, n. the science that deals with the material universe beyond the earth s atmosphere. [1175 1225; ME astronomie ( < AF) < L astronomia < Gk. See ASTRO , NOMY] * * * I Science dealing with the origin, evolution, composition,… …
87Observational astronomy — Mayall telescope at Kitt Peak National Observatory Observational astronomy is a division of the astronomical science that is concerned with getting data, in contrast with theoretical astrophysics which is mainly concerned with finding out the… …
88Observational cosmology — Physical cosmology Universe · Big Bang …
89Weak gravitational lensing — While the presence of any mass bends the path of light passing near it, this effect rarely produces the giant arcs and multiple images associated with strong gravitational lensing. Most lines of sight in the universe are thoroughly in the weak… …
90On Vision and Colors — (German: Über das Sehn und die Farben) is a treatise[1] by Arthur Schopenhauer that was published in May 1816 when the author was 28 years old. Schopenhauer had extensively discussed with Johann Wolfgang von Goethe about the poet s Theory of… …
