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Archimedes Palimpsest
The Archimedes Palimpsest is a parchment codex palimpsest, originally a Byzantine Greek copy of a compilation of Archimedes and other authors. It contains two works of Archimedes that were thought to have been lost (the '' Ostomachion'' and the ''Method of Mechanical Theorems'') and the only surviving original Greek edition of his work '' On Floating Bodies''. The first version of the compilation is believed to have been produced by Isidorus of Miletus, the architect of the geometrically complex Hagia Sophia cathedral in Constantinople, sometime around AD 530. The copy found in the palimpsest was created from this original, also in Constantinople, during the Macedonian Renaissance (c. AD 950), a time when mathematics in the capital was being revived by the former Greek Orthodox bishop of Thessaloniki Leo the Geometer, a cousin of the Patriarch. Following the sack of Constantinople by Western crusaders in 1204, the manuscript was taken to an isolated Greek monastery in Palestin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sack Of Constantinople
The sack of Constantinople occurred in April 1204 and marked the culmination of the Fourth Crusade. Crusader armies captured, looted, and destroyed parts of Constantinople, then the capital of the Byzantine Empire. After the capture of the city, the Latin Empire (known to the Byzantines as the ''Frankokratia'' or the Latin Occupation) was established and Baldwin of Flanders was crowned Emperor Baldwin I of Constantinople in the Hagia Sophia. After the city's sacking, most of the Byzantine Empire's territories were divided up among the Crusaders. Byzantine aristocrats also established a number of small independent splinter states, one of them being the Empire of Nicaea, which would eventually recapture Constantinople in 1261 and proclaim the reinstatement of the Empire. However, the restored Empire never managed to reclaim its former territorial or economic strength, and eventually fell to the rising Ottoman Empire in the 1453 Siege of Constantinople. The Byzantine Empire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Public Domain
The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because those rights have expired, anyone can legally use or reference those works without permission. As examples, the works of William Shakespeare, Ludwig van Beethoven, Leonardo da Vinci and Georges Méliès are in the public domain either by virtue of their having been created before copyright existed, or by their copyright term having expired. Some works are not covered by a country's copyright laws, and are therefore in the public domain; for example, in the United States, items excluded from copyright include the formulae of Newtonian physics, cooking recipes,Copyright Protection No ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Pennsylvania Libraries
The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universities by numerous organizations and scholars. While the university dates its founding to 1740, it was created by Benjamin Franklin and other Philadelphia citizens in 1749. It is a member of the Ivy League. The university has four undergraduate schools as well as twelve graduate and professional schools. Schools enrolling undergraduates include the College of Arts and Sciences, the School of Engineering and Applied Science, the Wharton School, and the School of Nursing. Among its highly ranked graduate schools are its law school, whose first professor wrote the first draft of the United States Constitution, its medical school, the first in North America, and Wharton, the first collegiate business school. Penn's endowment is US$20.7 billion, p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CC BY
A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work".A "work" is any creative material made by a person. A painting, a graphic, a book, a song/lyrics to a song, or a photograph of almost anything are all examples of "works". A CC license is used when an author wants to give other people the right to share, use, and build upon a work that the author has created. CC provides an author flexibility (for example, they might choose to allow only non-commercial uses of a given work) and protects the people who use or redistribute an author's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work. There are several types of Creative Commons licenses. Each license differs by several combinations that condition the terms of distribution. They were initially released on December 16, 2002, by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Creative Commons License
A Creative Commons (CC) license is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted "work".A "work" is any creative material made by a person. A painting, a graphic, a book, a song/lyrics to a song, or a photograph of almost anything are all examples of "works". A CC license is used when an author wants to give other people the right to share, use, and build upon a work that the author has created. CC provides an author flexibility (for example, they might choose to allow only non-commercial uses of a given work) and protects the people who use or redistribute an author's work from concerns of copyright infringement as long as they abide by the conditions that are specified in the license by which the author distributes the work. There are several types of Creative Commons licenses. Each license differs by several combinations that condition the terms of distribution. They were initially released on December 16, 2002, by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . X-ray wavelengths are shorter than those of ultraviolet rays and longer than those of gamma rays. There is no universally accepted, strict definition of the bounds of the X-ray band. Roughly, X-rays have a wavelength ranging from 10 nanometers to 10 picometers, corresponding to frequencies in the range of 30 petahertz to 30 exahertz ( to ) and photon energies in the range of 100 eV to 100 keV, respectively. X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography is widely used in medi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raking Light
Raking light, the illumination of objects from a light source at an oblique angle or almost parallel to the surface, provides information on the surface topography and relief of the artefact thus lit. It is widely used in the examination of works of art. Examination of paintings Using raking light, the effects of impasto and the surface texture of a painting are accentuated by the increased illumination of surfaces facing the light source and the exaggeration of shadows on surfaces facing away from the light source. In some instances raking light may help reveal pentimenti (changes in an artist's intention). In the case of wall paintings, raking light helps show preparatory techniques such as incisions in the plaster support. Conservation Conservators examine objects under raking light during visual inspection and for condition recording. In the examination of easel paintings, raking light may help document craquelure, paint cupping, uneven tension in a canvas, or warp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Infrared
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around 1 millimeter (300 GHz) to the nominal red edge of the visible spectrum, around 700 nanometers (430 THz). Longer IR wavelengths (30 μm-100 μm) are sometimes included as part of the terahertz radiation range. Almost all black-body radiation from objects near room temperature is at infrared wavelengths. As a form of electromagnetic radiation, IR propagates energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon. It was long known that fires emit invisible heat; in 1681 the pioneering experimenter Edme Mariotte showed that glass, though transparent to sunlight, obstructed radiant heat. In 1800 the astronomer Sir William Herschel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionize atoms, it can cause chemical reactions and causes many substances to glow or fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surfaces with which it comes into contac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeff Bezos
Jeffrey Preston Bezos ( ;; and Robinson (2010), p. 7. ''né'' Jorgensen; born January 12, 1964) is an American entrepreneur, media proprietor, investor, and commercial astronaut. He is the founder, executive chairman, and former president and CEO of Amazon. With a net worth of US$114.5 billion as of November 2022, Bezos is the fourth-wealthiest person in the world and was the wealthiest from 2017 to 2021 according to both Bloomberg's '' Billionaires Index'' and ''Forbes''. Born in Albuquerque and raised in Houston and Miami, Bezos graduated from Princeton University in 1986. He holds a degree in electrical engineering and computer science. He worked on Wall Street in a variety of related fields from 1986 to early 1994. Bezos founded Amazon in late 1994 on a road trip from New York City to Seattle. The company began as an online bookstore and has since expanded to a variety of other e-commerce products and services, including video and audio streaming, cloud computing, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Johan Ludvig Heiberg (historian)
Johan Ludvig Heiberg (27 November 1854 – 4 January 1928) was a Danish philologist and historian. He is best known for his discovery of previously unknown texts in the Archimedes Palimpsest, and for his edition of ''Euclid's Elements'' that T. L. Heath translated into English. He also published an edition of Ptolemy's ''Almagest''. Early life and education Heiberg was born in Aalborg, the son of medical doctor Emil Theodor Heiberg (1820–93) and Johanne (Hanne) Henriette Jacoba Schmidt (1821–83). He was related to 19th-century Danish poet Johan Ludvig Heiberg (1791-1860). His sister, Johanne Louise Heiberg (1860–1934), married biochemist Max Henius (1859–1935). Heiberg matriculated from Aalborg Cathedral School in 1871. He and acquired a degree in classical philology from the University of Copenhagen in 1876 and spent the next few years teaching. He acquired a doctorate degree with the dissertation ''Quæstiones Archimedeæ'' in 1879. Career From 1884 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
