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Ancient Egypt was a civilization of ancient Northeast Africa. It was concentrated along the lower reaches of the Nile River, situated in the place that is now the country Egypt. Ancient Egyptian civilization followed prehistoric Egypt and coalesced around 3100 BC (according to conventional Egyptian chronology) [ 1 ] with the political ...
Here () is the reflectivity, = /, is the X-ray wavelength (typically copper's K-alpha peak at 0.154056 nm), is the density deep within the material and is the angle of incidence. Below the critical angle Q < Q c {\displaystyle Q<Q_{c}} (derived from Snell's law ), 100% of incident radiation is reflected through total external reflection , R ...
38,160.87 ha. Machu Picchu[ a] is a 15th-century Inca citadel located in the Eastern Cordillera of southern Peru on a mountain ridge at 2,430 meters (7,970 ft). [ 8] Often referred to as the "Lost City of the Incas", [ 9] it is the most familiar icon of the Inca Empire. It is located in the Machupicchu District within Urubamba Province [ 10 ...
The metal silver (formerly necessary to the radiographic & photographic industries) is a non-renewable resource although silver can easily be reclaimed from spent X-ray film. [8] Where X-ray films required wet processing facilities, newer digital technologies do not. Digital archiving of images also saves physical storage space. [9]
The hypothesis of dark matter has an elaborate history. [18] [19] In the appendices of the book Baltimore lectures on molecular dynamics and the wave theory of light where the main text was based on a series of lectures given in 1884, [18] Lord Kelvin discussed the potential number of stars around the Sun from the observed velocity dispersion of the stars near the Sun, assuming that the Sun ...
Lithium. body-centered cubic (bcc) ( cI2) Lithium (from Ancient Greek λίθος (líthos) 'stone'; symbol Li and atomic number 3) is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable, and must be stored ...
Homosexuality in ancient Rome often differs markedly from the contemporary West. Latin lacks words that would precisely translate "homosexual" and "heterosexual". [ 1] The primary dichotomy of ancient Roman sexuality was active / dominant / masculine and passive / submissive / feminine. Roman society was patriarchal, and the freeborn male ...
99942 Apophis (provisional designation 2004 MN 4) is a near-Earth asteroid and a potentially hazardous object with a diameter of 370 metres (1,210 feet) [3] that caused a brief period of concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029.