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[SOURCE: https://en.wikipedia.org/wiki/Little_Implementation_Language] | [TOKENS: 158] |
Contents Little Implementation Language LIL, the Little Implementation Language, was a system programming language during the early days of Unix history on PDP-11 machines. It was written by P. J. Plauger of Bell Labs. LIL attempted to fill the gap between assemblers and machine-independent system implementation languages (such as the C programming language), by basically adding structured programming to the PDP-11 assembly language. LIL resembled PL360 with C-like flow control syntax. The LIL compiler "lc" was part of Fifth Edition Unix (1974), but was dropped by Sixth Edition Unix (1975). Plauger left Bell Labs in the same year. Plauger explains why LIL was abandoned in Bell Labs in favor of C: See also References External resources |
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[SOURCE: https://en.wikipedia.org/wiki/Galactic_habitable_zone] | [TOKENS: 3008] |
Contents Galactic habitable zone In astrobiology and planetary astrophysics, the galactic habitable zone is the region of a galaxy in which life is most likely to develop. The concept of a galactic habitable zone analyzes various factors, such as metallicity (the presence of elements heavier than hydrogen and helium) and the rate and density of major catastrophes such as supernovae, and uses these to calculate which regions of a galaxy are more likely to form terrestrial planets, initially develop simple life, and provide a suitable environment for this life to evolve and advance. According to research published in August 2015, very large galaxies may favor the birth and development of habitable planets more than smaller galaxies. In the case of the Milky Way, its galactic habitable zone is commonly believed to be an annulus with an outer radius of about 10 kiloparsecs (33,000 ly) and an inner radius close to the Galactic Center (with both radii lacking hard boundaries). Galactic habitable-zone theory has been criticized due to an inability to accurately quantify the factors making a region of a galaxy favorable for the emergence of life. In addition, computer simulations suggest that stars may change their orbits around the galactic center significantly, therefore challenging at least part of the view that some galactic areas are necessarily more life-supporting than others. History The idea of the circumstellar habitable zone was introduced in 1953 by Hubertus Strughold and Harlow Shapley and in 1959 by Su-Shu Huang as the region around a star in which an orbiting planet could retain water at its surface. From the 1970s, planetary scientists and astrobiologists began to consider various other factors required for the creation and sustenance of life, including the impact that a nearby supernova may have on the development of life. In 1981, computer scientist Jim Clarke proposed that the apparent lack of extraterrestrial civilizations in the Milky Way could be explained by Seyfert-type outbursts from an active galactic nucleus, with Earth alone being spared from this radiation by virtue of its location in the galaxy. In the same year, Wallace Hampton Tucker analyzed galactic habitability in a more general context, but later work superseded his proposals. Modern galactic habitable-zone theory was introduced in 1986 by L.S. Marochnik and L.M. Mukhin of the Russian Space Research Institute, who defined the zone as the region in which intelligent life could flourish. Donald Brownlee and palaeontologist Peter Ward expanded upon the concept of a galactic habitable zone, as well as the other factors required for the emergence of complex life, in their 2000 book Rare Earth: Why Complex Life is Uncommon in the Universe. In that book, the authors used the galactic habitable zone, among other factors, to argue that intelligent life is not a common occurrence in the Universe. The idea of a galactic habitable zone was further developed in 2001 in a paper by Ward and Brownlee, in collaboration with Guillermo Gonzalez of the University of Washington. In that paper, Gonzalez, Brownlee, and Ward stated that regions near the galactic halo would lack the heavier elements required to produce habitable terrestrial planets, thus creating an outward limit to the size of the galactic habitable zone. Being too close to the galactic center, however, would expose an otherwise habitable planet to numerous supernovae and other energetic cosmic events, as well as excessive cometary impacts caused by perturbations of the host star's Oort cloud. Therefore, the authors established an inner boundary for the galactic habitable zone, located just outside the galactic bulge. Considerations In order to identify a location in the galaxy as being a part of the galactic habitable zone, a variety of factors must be accounted for. These include the distribution of stars and spiral arms, the presence or absence of an active galactic nucleus, the frequency of nearby supernovae that can threaten the existence of life, the metallicity of that location, and other factors. Without fulfilling these factors, a region of the galaxy cannot create or sustain life with efficiency. One of the most basic requirements for the existence of life around a star is the ability of that star to produce a terrestrial planet of sufficient mass to sustain it. Various elements, such as iron, magnesium, titanium, carbon, oxygen, silicon, and others, are required to produce habitable planets, and the concentration and ratios of these vary throughout the galaxy. The most common benchmark elemental ratio is that of Fe/H, one of the factors determining the propensity of a region of the galaxy to produce terrestrial planets. The galactic bulge, the region of the galaxy closest to the Galactic Center, has an [Fe/H] distribution peaking at −0.2 decimal exponent units (dex) relative to the Sun's ratio (where −1 would be 1⁄10 such metallicity); the thin disk, in which local sectors of the local Arm are, has an average metallicity of −0.02 dex at the orbital distance of the Sun around the galactic center, reducing by 0.07 dex for every additional kiloparsec of orbital distance. The extended thick disk has an average [Fe/H] of −0.6 dex, while the halo, the region farthest from the galactic center, has the lowest [Fe/H] distribution peak, at around −1.5 dex. In addition, ratios such as [C/O], [Mg/Fe], [Si/Fe], and [S/Fe] may be relevant to the ability of a region of a galaxy to form habitable terrestrial planets, and of these [Mg/Fe] and [Si/Fe] are slowly reducing over time, meaning that future terrestrial planets are more likely to possess larger iron cores. In addition to specific amounts of the various stable elements that comprise a terrestrial planet's mass, an abundance of radionuclides such as 40K, 235U, 238U, and 232Th is required in order to heat the planet's interior and power life-sustaining processes such as plate tectonics, volcanism, and a geomagnetic dynamo. The [U/H] and [Th/H] ratios are dependent on the [Fe/H] ratio; however, a general function for the abundance of 40K cannot be created with existing data. Even on a habitable planet with enough radioisotopes to heat its interior, various prebiotic molecules are required in order to produce life; therefore, the distribution of these molecules in the galaxy is important in determining the galactic habitable zone. A 2008 study by Samantha Blair and colleagues attempted to determine the outer edge of the galactic habitable zone by means of analyzing formaldehyde and carbon monoxide emissions from various giant molecular clouds scattered throughout the Milky Way; however, the data is neither conclusive nor complete. While high metallicity is beneficial for the creation of terrestrial extrasolar planets, an excess amount can be harmful for life. Excess metallicity may lead to the formation of a large number of gas giants in a given system, which may subsequently migrate from beyond the system's frost line and become hot Jupiters, disturbing planets that would otherwise have been located in the system's circumstellar habitable zone. Thus, it was found that the Goldilocks principle applies to metallicity as well; low-metallicity systems have low probabilities of forming terrestrial-mass planets at all, while excessive metallicities cause a large number of gas giants to develop, disrupting the orbital dynamics of the system and altering the habitability of terrestrial planets in the system. As well as being in a region of the galaxy that is chemically advantageous for the development of life, a star must also avoid an excessive number of catastrophic cosmic events with the potential to damage life on its otherwise habitable planets. Nearby supernovae, for example, have the potential to severely harm life on a planet; with excessive frequency, such catastrophic outbursts have the potential to sterilize an entire region of a galaxy for billions of years. The galactic bulge, for example, experienced an initial wave of extremely rapid star formation, triggering a cascade of supernovae that for five billion years left that area almost completely unable to develop life. In addition to supernovae, gamma-ray bursts, excessive amounts of radiation, gravitational perturbations and various other events have been proposed to affect the distribution of life within the galaxy. These include, controversially, such proposals as "galactic tides" with the potential to induce cometary impacts or even cold bodies of dark matter that pass through organisms and induce genetic mutations. However, the impact of many of these events may be difficult to quantify. Various morphological features of galaxies can affect their potential for habitability. Spiral arms, for example, are the location of star formation, but they contain numerous giant molecular clouds and a high density of stars that can perturb a star's Oort cloud, sending avalanches of comets and asteroids toward any planets further in. In addition, the high density of stars and rate of massive star formation can expose any stars orbiting within the spiral arms for too long to supernova explosions, reducing their prospects for the survival and development of life. Considering these factors, the Sun is advantageously placed within the galaxy because, in addition to being outside a spiral arm, it orbits near the corotation circle, maximizing the interval between spiral-arm crossings. Spiral arms also have the ability to cause climatic changes on a planet. Passing through the dense molecular clouds of galactic spiral arms, stellar winds may be pushed back to the point that a reflective hydrogen layer accumulates in an orbiting planet's atmosphere, perhaps leading to a snowball Earth scenario. A galactic bar also has the potential to affect the size of the galactic habitable zone. Galactic bars are thought to grow over time, eventually reaching the corotation radius of the galaxy and perturbing the orbits of the stars already there. High-metallicity stars like the Sun, for example, at an intermediate location between the low-metallicity galactic halo and the high-radiation galactic center, may be scattered throughout the galaxy, affecting the definition of the galactic habitable zone. It has been suggested that for this reason, it may be impossible to properly define a galactic habitable zone. Boundaries Early research on the galactic habitable zone, including the 2001 paper by Gonzalez, Brownlee, and Ward, did not demarcate any specific boundaries, merely stating that the zone was an annulus encompassing a region of the galaxy that was both enriched with metals and spared from excessive radiation, and that habitability would be more likely in the galaxy's thin disk. However, later research conducted in 2004 by Lineweaver and colleagues did create boundaries for this annulus, in the case of the Milky Way ranging from 7 kpc to 9 kpc from the galactic center. The Lineweaver team also analyzed the evolution of the galactic habitable zone with respect to time, finding, for example, that stars close to the galactic bulge had to form within a time window of about two billion years in order to have habitable planets. Before that window, galactic-bulge stars would be prevented from having life-sustaining planets from frequent supernova events. After the supernova threat had subsided, though, the increasing metallicity of the galactic core would eventually mean that stars there would have a high number of giant planets, with the potential to destabilize star systems and radically alter the orbit of any planet located in a star's circumstellar habitable zone. Simulations conducted in 2005 at the University of Washington, however, show that even in the presence of hot Jupiters, terrestrial planets may remain stable over long timescales. A 2006 study by Milan Ćirković and colleagues extended the notion of a time-dependent galactic habitable zone, analyzing various catastrophic events as well as the underlying secular evolution of galactic dynamics. The paper considers that the number of habitable planets may fluctuate wildly with time due to the unpredictable timing of catastrophic events, thereby creating a punctuated equilibrium in which habitable planets are more likely at some times than at others. Based on the results of Monte Carlo simulations on a toy model of the Milky Way, the team found that the number of habitable planets is likely to increase with time, though not in a perfectly linear pattern. Subsequent studies saw more fundamental revision of the old concept of the galactic habitable zone as an annulus. In 2008, a study by Nikos Prantzos revealed that, while the probability of a planet escaping sterilization by supernova was highest at a distance of about 10 kpc from the galactic center, the sheer density of stars in the inner galaxy meant that the highest number of habitable planets could be found there. The research was corroborated in a 2011 paper by Michael Gowanlock, who calculated the frequency of supernova-surviving planets as a function of their distance from the galactic center, their height above the galactic plane, and their age, ultimately discovering that about 0.3% of stars in the galaxy could today support complex life, or 1.2% if one does not consider the tidal locking of red dwarf planets as precluding the development of complex life. Criticism The idea of the galactic habitable zone has been criticized by Nikos Prantzos, on the grounds that the parameters to create it are impossible to define even approximately, and that thus the galactic habitable zone may merely be a useful conceptual tool to enable a better understanding of the distribution of life, rather than an end to itself. For these reasons, Prantzos has suggested that the entire galaxy may be habitable, rather than habitability being restricted to a specific region in space and time. In addition, stars "riding" the galaxy's spiral arms may move tens of thousands of light years from their original orbits, thus supporting the notion that there may not be one specific galactic habitable zone. A Monte Carlo simulation, improving on the mechanisms used by Ćirković in 2006, was conducted in 2010 by Duncan Forgan of Royal Observatory Edinburgh. The data collected from the experiments support Prantzos's notion that there is no solidly defined galactic habitable zone, indicating the possibility of hundreds of extraterrestrial civilizations in the Milky Way, though further data will be required in order for a definitive determination to be made. See also References External links Media related to Habitable zone at Wikimedia Commons |
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[SOURCE: https://en.wikipedia.org/wiki/LilyPond] | [TOKENS: 1272] |
Contents LilyPond LilyPond is a computer program and file format for music engraving. One of LilyPond's major goals is to produce scores that are engraved with traditional layout rules, reflecting the era when scores were engraved by hand. LilyPond is cross-platform, and is available for several common operating systems; released under the terms of the GNU General Public License, LilyPond is free software and part of the GNU Project. History The LilyPond project was started in 1996 by Han-Wen Nienhuys and Jan Nieuwenhuizen, after they decided to abandon work on MPP (MusiXTeX PreProcessor), a project they began collaborating on in 1995. Its name was inspired both by the Rosegarden project and an acquaintance of Nienhuys and Nieuwenhuizen named Suzanne, a name that means lily in Hebrew (שׁוֹשַׁנָּה). LilyPond 1.0 was released on July 31, 1998, highlighting the development of a custom music font, Feta, and the complete separation of LilyPond from MusiXTeX. LilyPond 2.0 was released on September 24, 2003, announcing a simplified syntax model and a much more complete set of facilities for notating various styles of music. Design LilyPond is mostly written in C++ and uses Scheme (interpreted by GNU Guile) as its extension language, allowing for user customization. It has a relatively large codebase; as of March 10, 2017, the source includes over 600,000 lines of C++, 140,000 lines of Scheme, and 120,000 lines of Python code. It uses a simple text notation for music input, which LilyPond interprets and processes in a series of stages. In the final stage, music notation is output to PDF (via PostScript) or other graphical formats, such as SVG or PNG. LilyPond can also generate MIDI files that correspond to the music notation output. LilyPond is a text-based application, so it does not contain its own graphical user interface to assist with score creation. (However, a text-editor based "LilyPad" GUI for Windows and MacOS is included by default on these systems.) It does, however, have a flexible input language that strives to be simple, easing the learning curve for new users. LilyPond adheres to the WYSIWYM paradigm; the workflow for typesetting music notation with LilyPond is similar to that of preparing documents with LaTeX. LilyPond supports experimental musical notation. Its guitar facilities support alternative tunings, such as major-thirds tuning. Software features LilyPond's primary goal is to produce output comparable to professionally engraved scores instead of output that looks mechanical and computer-generated. An essay from the LilyPond website, written by LilyPond developers, explains some typographical issues addressed by LilyPond: Overview of input syntax The native input language for LilyPond is comprehensive, and consists of many commands needed for expressing any sort of articulation, dynamic, meter, etc. It is similar to that of TeX. The ability to embed Scheme code within a LilyPond source file permits arbitrary extensions to the input language and assists with algorithmic composition. Some general syntactic features are listed below. LilyPond's interface with Pango requires the input character encoding to be UTF-8. One benefit of this is that more than one language can be included in the same source file. Example of LilyPond input file Lilypond can also create extensively customised output. An example is the short extract of a Karlheinz Stockhausen piano piece below. Collaboration with other projects Several graphical scorewriters—such as Rosegarden, NoteEdit, Canorus, Denemo, and TuxGuitar—can export files directly to LilyPond format. Other graphical applications serve as front ends to LilyPond, including Frescobaldi (written in Python, maintained by Wilbert Berendsen) and the LilyPondTool plugin for jEdit. Denemo integrates the PDF output of LilyPond in its display, allowing some editing operations on the final typeset score. The Mutopia Project, which distributes free content sheet music, uses LilyPond to typeset its music, as does Musipedia, a collaborative music encyclopedia. Emacs' org-mode contains support for embedding LilyPond scores into documents. OOoLilyPond, a LibreOffice extension, provides support for calling LilyPond to embed scores into documents. Lilypond is available in MediaWiki via the Score extension code. This, for example, transforms the notation into The above is an excerpt from Ludwig van Beethoven's 9th Symphony, commonly known as "Ode to Joy". More complex scores, including lyrics, are also possible within MediaWiki wikis. See Pastime with Good Company or Il Canto degli Italiani for an example of this. Integration of LilyPond musical elements into various document formats (both TeX-based systems such as LaTeX and Texinfo, and also DocBook and HTML pages) is natively supported through the companion program lilypond-book, developed and maintained by the LilyPond community. This allows users to embed musical elements within texts, such as musicology, song booklets, work sheets for teaching, and school examinations. For integration into the LaTeX document preparation system, lyLuaTeX has been developed as a LuaLaTeX package to embed musical elements within texts. It includes features for matching layout and appearance of the musical elements with the surrounding text document. Music elements may consist of music symbols, song lyrics, guitar chords diagrams, lead sheets, music excerpts, guitar tablatures, or multi-page scores. Comparison to other scorewriters Finale and Sibelius are two proprietary scorewriters often compared to LilyPond. Andrew Hawryluk, a LilyPond user, wrote a series of articles comparing output quality between Finale and LilyPond. Another scorewriter with comparable features to LilyPond is SCORE, but SCORE relies on manual positioning more than Lilypond does. See also Comparison of scorewriters. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Limbo_(programming_language)] | [TOKENS: 359] |
Contents Limbo (programming language) Limbo is a programming language for writing distributed systems and is the language used to write applications for the Inferno operating system. It was designed at Bell Labs by Sean Dorward, Phil Winterbottom, and Rob Pike. The Limbo compiler generates architecture-independent object code which is then interpreted by the Dis virtual machine or compiled just before runtime to improve performance. Therefore all Limbo applications are completely portable across all Inferno platforms. Limbo's approach to concurrency was inspired by Hoare's communicating sequential processes (CSP), as implemented and amended in Pike's earlier Newsqueak language and Winterbottom's Alef. Language features Limbo supports the following features: Virtual machine The Dis virtual machine that executes Limbo code is a CISC-like VM, with instructions for arithmetic, control flow, data motion, process creation, synchronizing and communicating between processes, loading modules of code, and support for higher-level data-types: strings, arrays, lists, and communication channels. It uses a hybrid of reference counting and a real-time garbage-collector for cyclic data. Aspects of the design of Dis were inspired by the AT&T Hobbit microprocessor, as used in the original BeBox. Examples Limbo uses Ada-style definitions as in: Books The 3rd edition of the Inferno operating system and Limbo programming language are described in the textbook Inferno Programming with Limbo ISBN 0-470-84352-7 (Chichester: John Wiley & Sons, 2003), by Phillip Stanley-Marbell. Another textbook The Inferno Programming Book: An Introduction to Programming for the Inferno Distributed System, by Martin Atkins, Charles Forsyth, Rob Pike and Howard Trickey, was started, but never released. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/File:Nouvelle-France_map-en.svg] | [TOKENS: 109] |
File:Nouvelle-France map-en.svg Summary Own work using: Licensing File history Click on a date/time to view the file as it appeared at that time. File usage The following 54 pages use this file: Global file usage The following other wikis use this file: View more global usage of this file. Metadata This file contains additional information, probably added from the digital camera or scanner used to create or digitize it. If the file has been modified from its original state, some details may not fully reflect the modified file. |
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[SOURCE: https://en.wikipedia.org/wiki/Lod#cite_note-91] | [TOKENS: 4733] |
Contents Lod Lod (Hebrew: לוד, fully vocalized: לֹד), also known as Lydda (Ancient Greek: Λύδδα) and Lidd (Arabic: اللِّدّ, romanized: al-Lidd, or اللُّدّ, al-Ludd), is a city 15 km (9+1⁄2 mi) southeast of Tel Aviv and 40 km (25 mi) northwest of Jerusalem in the Central District of Israel. It is situated between the lower Shephelah on the east and the coastal plain on the west. The city had a population of 90,814 in 2023. Lod has been inhabited since at least the Neolithic period. It is mentioned a few times in the Hebrew Bible and in the New Testament. Between the 5th century BCE and up until the late Roman period, it was a prominent center for Jewish scholarship and trade. Around 200 CE, the city became a Roman colony and was renamed Diospolis (Ancient Greek: Διόσπολις, lit. 'city of Zeus'). Tradition identifies Lod as the 4th century martyrdom site of Saint George; the Church of Saint George and Mosque of Al-Khadr located in the city is believed to have housed his remains. Following the Arab conquest of the Levant, Lod served as the capital of Jund Filastin; however, a few decades later, the seat of power was transferred to Ramla, and Lod slipped in importance. Under Crusader rule, the city was a Catholic diocese of the Latin Church and it remains a titular see to this day.[citation needed] Lod underwent a major change in its population in the mid-20th century. Exclusively Palestinian Arab in 1947, Lod was part of the area designated for an Arab state in the United Nations Partition Plan for Palestine; however, in July 1948, the city was occupied by the Israel Defense Forces, and most of its Arab inhabitants were expelled in the Palestinian expulsion from Lydda and Ramle. The city was largely resettled by Jewish immigrants, most of them expelled from Arab countries. Today, Lod is one of Israel's mixed cities, with an Arab population of 30%. Lod is one of Israel's major transportation hubs. The main international airport, Ben Gurion Airport, is located 8 km (5 miles) north of the city. The city is also a major railway and road junction. Religious references The Hebrew name Lod appears in the Hebrew Bible as a town of Benjamin, founded along with Ono by Shamed or Shamer (1 Chronicles 8:12; Ezra 2:33; Nehemiah 7:37; 11:35). In Ezra 2:33, it is mentioned as one of the cities whose inhabitants returned after the Babylonian captivity. Lod is not mentioned among the towns allocated to the tribe of Benjamin in Joshua 18:11–28. The name Lod derives from a tri-consonantal root not extant in Northwest Semitic, but only in Arabic (“to quarrel; withhold, hinder”). An Arabic etymology of such an ancient name is unlikely (the earliest attestation is from the Achaemenid period). In the New Testament, the town appears in its Greek form, Lydda, as the site of Peter's healing of Aeneas in Acts 9:32–38. The city is also mentioned in an Islamic hadith as the location of the battlefield where the false messiah (al-Masih ad-Dajjal) will be slain before the Day of Judgment. History The first occupation dates to the Neolithic in the Near East and is associated with the Lodian culture. Occupation continued in the Levant Chalcolithic. Pottery finds have dated the initial settlement in the area now occupied by the town to 5600–5250 BCE. In the Early Bronze, it was an important settlement in the central coastal plain between the Judean Shephelah and the Mediterranean coast, along Nahal Ayalon. Other important nearby sites were Tel Dalit, Tel Bareqet, Khirbat Abu Hamid (Shoham North), Tel Afeq, Azor and Jaffa. Two architectural phases belong to the late EB I in Area B. The first phase had a mudbrick wall, while the late phase included a circulat stone structure. Later excavations have produced an occupation later, Stratum IV. It consists of two phases, Stratum IVb with mudbrick wall on stone foundations and rounded exterior corners. In Stratum IVa there was a mudbrick wall with no stone foundations, with imported Egyptian potter and local pottery imitations. Another excavations revealed nine occupation strata. Strata VI-III belonged to Early Bronze IB. The material culture showed Egyptian imports in strata V and IV. Occupation continued into Early Bronze II with four strata (V-II). There was continuity in the material culture and indications of centralized urban planning. North to the tell were scattered MB II burials. The earliest written record is in a list of Canaanite towns drawn up by the Egyptian pharaoh Thutmose III at Karnak in 1465 BCE. From the fifth century BCE until the Roman period, the city was a centre of Jewish scholarship and commerce. According to British historian Martin Gilbert, during the Hasmonean period, Jonathan Maccabee and his brother, Simon Maccabaeus, enlarged the area under Jewish control, which included conquering the city. The Jewish community in Lod during the Mishnah and Talmud era is described in a significant number of sources, including information on its institutions, demographics, and way of life. The city reached its height as a Jewish center between the First Jewish-Roman War and the Bar Kokhba revolt, and again in the days of Judah ha-Nasi and the start of the Amoraim period. The city was then the site of numerous public institutions, including schools, study houses, and synagogues. In 43 BC, Cassius, the Roman governor of Syria, sold the inhabitants of Lod into slavery, but they were set free two years later by Mark Antony. During the First Jewish–Roman War, the Roman proconsul of Syria, Cestius Gallus, razed the town on his way to Jerusalem in Tishrei 66 CE. According to Josephus, "[he] found the city deserted, for the entire population had gone up to Jerusalem for the Feast of Tabernacles. He killed fifty people whom he found, burned the town and marched on". Lydda was occupied by Emperor Vespasian in 68 CE. In the period following the destruction of Jerusalem in 70 CE, Rabbi Tarfon, who appears in many Tannaitic and Jewish legal discussions, served as a rabbinic authority in Lod. During the Kitos War, 115–117 CE, the Roman army laid siege to Lod, where the rebel Jews had gathered under the leadership of Julian and Pappos. Torah study was outlawed by the Romans and pursued mostly in the underground. The distress became so great, the patriarch Rabban Gamaliel II, who was shut up there and died soon afterwards, permitted fasting on Ḥanukkah. Other rabbis disagreed with this ruling. Lydda was next taken and many of the Jews were executed; the "slain of Lydda" are often mentioned in words of reverential praise in the Talmud. In 200 CE, emperor Septimius Severus elevated the town to the status of a city, calling it Colonia Lucia Septimia Severa Diospolis. The name Diospolis ("City of Zeus") may have been bestowed earlier, possibly by Hadrian. At that point, most of its inhabitants were Christian. The earliest known bishop is Aëtius, a friend of Arius. During the following century (200-300CE), it's said that Joshua ben Levi founded a yeshiva in Lod. In December 415, the Council of Diospolis was held here to try Pelagius; he was acquitted. In the sixth century, the city was renamed Georgiopolis after St. George, a soldier in the guard of the emperor Diocletian, who was born there between 256 and 285 CE. The Church of Saint George and Mosque of Al-Khadr is named for him. The 6th-century Madaba map shows Lydda as an unwalled city with a cluster of buildings under a black inscription reading "Lod, also Lydea, also Diospolis". An isolated large building with a semicircular colonnaded plaza in front of it might represent the St George shrine. After the Muslim conquest of Palestine by Amr ibn al-'As in 636 CE, Lod which was referred to as "al-Ludd" in Arabic served as the capital of Jund Filastin ("Military District of Palaestina") before the seat of power was moved to nearby Ramla during the reign of the Umayyad Caliph Suleiman ibn Abd al-Malik in 715–716. The population of al-Ludd was relocated to Ramla, as well. With the relocation of its inhabitants and the construction of the White Mosque in Ramla, al-Ludd lost its importance and fell into decay. The city was visited by the local Arab geographer al-Muqaddasi in 985, when it was under the Fatimid Caliphate, and was noted for its Great Mosque which served the residents of al-Ludd, Ramla, and the nearby villages. He also wrote of the city's "wonderful church (of St. George) at the gate of which Christ will slay the Antichrist." The Crusaders occupied the city in 1099 and named it St Jorge de Lidde. It was briefly conquered by Saladin, but retaken by the Crusaders in 1191. For the English Crusaders, it was a place of great significance as the birthplace of Saint George. The Crusaders made it the seat of a Latin Church diocese, and it remains a titular see. It owed the service of 10 knights and 20 sergeants, and it had its own burgess court during this era. In 1226, Ayyubid Syrian geographer Yaqut al-Hamawi visited al-Ludd and stated it was part of the Jerusalem District during Ayyubid rule. Sultan Baybars brought Lydda again under Muslim control by 1267–8. According to Qalqashandi, Lydda was an administrative centre of a wilaya during the fourteenth and fifteenth century in the Mamluk empire. Mujir al-Din described it as a pleasant village with an active Friday mosque. During this time, Lydda was a station on the postal route between Cairo and Damascus. In 1517, Lydda was incorporated into the Ottoman Empire as part of the Damascus Eyalet, and in the 1550s, the revenues of Lydda were designated for the new waqf of Hasseki Sultan Imaret in Jerusalem, established by Hasseki Hurrem Sultan (Roxelana), the wife of Suleiman the Magnificent. By 1596 Lydda was a part of the nahiya ("subdistrict") of Ramla, which was under the administration of the liwa ("district") of Gaza. It had a population of 241 households and 14 bachelors who were all Muslims, and 233 households who were Christians. They paid a fixed tax-rate of 33,3 % on agricultural products, including wheat, barley, summer crops, vineyards, fruit trees, sesame, special product ("dawalib" =spinning wheels), goats and beehives, in addition to occasional revenues and market toll, a total of 45,000 Akçe. All of the revenue went to the Waqf. In 1051 AH/1641/2, the Bedouin tribe of al-Sawālima from around Jaffa attacked the villages of Subṭāra, Bayt Dajan, al-Sāfiriya, Jindās, Lydda and Yāzūr belonging to Waqf Haseki Sultan. The village appeared as Lydda, though misplaced, on the map of Pierre Jacotin compiled in 1799. Missionary William M. Thomson visited Lydda in the mid-19th century, describing it as a "flourishing village of some 2,000 inhabitants, imbosomed in noble orchards of olive, fig, pomegranate, mulberry, sycamore, and other trees, surrounded every way by a very fertile neighbourhood. The inhabitants are evidently industrious and thriving, and the whole country between this and Ramleh is fast being filled up with their flourishing orchards. Rarely have I beheld a rural scene more delightful than this presented in early harvest ... It must be seen, heard, and enjoyed to be appreciated." In 1869, the population of Ludd was given as: 55 Catholics, 1,940 "Greeks", 5 Protestants and 4,850 Muslims. In 1870, the Church of Saint George was rebuilt. In 1892, the first railway station in the entire region was established in the city. In the second half of the 19th century, Jewish merchants migrated to the city, but left after the 1921 Jaffa riots. In 1882, the Palestine Exploration Fund's Survey of Western Palestine described Lod as "A small town, standing among enclosure of prickly pear, and having fine olive groves around it, especially to the south. The minaret of the mosque is a very conspicuous object over the whole of the plain. The inhabitants are principally Moslim, though the place is the seat of a Greek bishop resident of Jerusalem. The Crusading church has lately been restored, and is used by the Greeks. Wells are found in the gardens...." From 1918, Lydda was under the administration of the British Mandate in Palestine, as per a League of Nations decree that followed the Great War. During the Second World War, the British set up supply posts in and around Lydda and its railway station, also building an airport that was renamed Ben Gurion Airport after the death of Israel's first prime minister in 1973. At the time of the 1922 census of Palestine, Lydda had a population of 8,103 inhabitants (7,166 Muslims, 926 Christians, and 11 Jews), the Christians were 921 Orthodox, 4 Roman Catholics and 1 Melkite. This had increased by the 1931 census to 11,250 (10,002 Muslims, 1,210 Christians, 28 Jews, and 10 Bahai), in a total of 2475 residential houses. In 1938, Lydda had a population of 12,750. In 1945, Lydda had a population of 16,780 (14,910 Muslims, 1,840 Christians, 20 Jews and 10 "other"). Until 1948, Lydda was an Arab town with a population of around 20,000—18,500 Muslims and 1,500 Christians. In 1947, the United Nations proposed dividing Mandatory Palestine into two states, one Jewish state and one Arab; Lydda was to form part of the proposed Arab state. In the ensuing war, Israel captured Arab towns outside the area the UN had allotted it, including Lydda. In December 1947, thirteen Jewish passengers in a seven-car convoy to Ben Shemen Youth Village were ambushed and murdered.In a separate incident, three Jewish youths, two men and a woman were captured, then raped and murdered in a neighbouring village. Their bodies were paraded in Lydda’s principal street. The Israel Defense Forces entered Lydda on 11 July 1948. The following day, under the impression that it was under attack, the 3rd Battalion was ordered to shoot anyone "seen on the streets". According to Israel, 250 Arabs were killed. Other estimates are higher: Arab historian Aref al Aref estimated 400, and Nimr al Khatib 1,700. In 1948, the population rose to 50,000 during the Nakba, as Arab refugees fleeing other areas made their way there. A key event was the Palestinian expulsion from Lydda and Ramle, with the expulsion of 50,000-70,000 Palestinians from Lydda and Ramle by the Israel Defense Forces. All but 700 to 1,056 were expelled by order of the Israeli high command, and forced to walk 17 km (10+1⁄2 mi) to the Jordanian Arab Legion lines. Estimates of those who died from exhaustion and dehydration vary from a handful to 355. The town was subsequently sacked by the Israeli army. Some scholars, including Ilan Pappé, characterize this as ethnic cleansing. The few hundred Arabs who remained in the city were soon outnumbered by the influx of Jews who immigrated to Lod from August 1948 onward, most of them from Arab countries. As a result, Lod became a predominantly Jewish town. After the establishment of the state, the biblical name Lod was readopted. The Jewish immigrants who settled Lod came in waves, first from Morocco and Tunisia, later from Ethiopia, and then from the former Soviet Union. Since 2008, many urban development projects have been undertaken to improve the image of the city. Upscale neighbourhoods have been built, among them Ganei Ya'ar and Ahisemah, expanding the city to the east. According to a 2010 report in the Economist, a three-meter-high wall was built between Jewish and Arab neighbourhoods and construction in Jewish areas was given priority over construction in Arab neighborhoods. The newspaper says that violent crime in the Arab sector revolves mainly around family feuds over turf and honour crimes. In 2010, the Lod Community Foundation organised an event for representatives of bicultural youth movements, volunteer aid organisations, educational start-ups, businessmen, sports organizations, and conservationists working on programmes to better the city. In the 2021 Israel–Palestine crisis, a state of emergency was declared in Lod after Arab rioting led to the death of an Israeli Jew. The Mayor of Lod, Yair Revivio, urged Prime Minister of Israel Benjamin Netanyahu to deploy Israel Border Police to restore order in the city. This was the first time since 1966 that Israel had declared this kind of emergency lockdown. International media noted that both Jewish and Palestinian mobs were active in Lod, but the "crackdown came for one side" only. Demographics In the 19th century and until the Lydda Death March, Lod was an exclusively Muslim-Christian town, with an estimated 6,850 inhabitants, of whom approximately 2,000 (29%) were Christian. According to the Israel Central Bureau of Statistics (CBS), the population of Lod in 2010 was 69,500 people. According to the 2019 census, the population of Lod was 77,223, of which 53,581 people, comprising 69.4% of the city's population, were classified as "Jews and Others", and 23,642 people, comprising 30.6% as "Arab". Education According to CBS, 38 schools and 13,188 pupils are in the city. They are spread out as 26 elementary schools and 8,325 elementary school pupils, and 13 high schools and 4,863 high school pupils. About 52.5% of 12th-grade pupils were entitled to a matriculation certificate in 2001.[citation needed] Economy The airport and related industries are a major source of employment for the residents of Lod. Other important factories in the city are the communication equipment company "Talard", "Cafe-Co" - a subsidiary of the Strauss Group and "Kashev" - the computer center of Bank Leumi. A Jewish Agency Absorption Centre is also located in Lod. According to CBS figures for 2000, 23,032 people were salaried workers and 1,405 were self-employed. The mean monthly wage for a salaried worker was NIS 4,754, a real change of 2.9% over the course of 2000. Salaried men had a mean monthly wage of NIS 5,821 (a real change of 1.4%) versus NIS 3,547 for women (a real change of 4.6%). The mean income for the self-employed was NIS 4,991. About 1,275 people were receiving unemployment benefits and 7,145 were receiving an income supplement. Art and culture In 2009-2010, Dor Guez held an exhibit, Georgeopolis, at the Petach Tikva art museum that focuses on Lod. Archaeology A well-preserved mosaic floor dating to the Roman period was excavated in 1996 as part of a salvage dig conducted on behalf of the Israel Antiquities Authority and the Municipality of Lod, prior to widening HeHalutz Street. According to Jacob Fisch, executive director of the Friends of the Israel Antiquities Authority, a worker at the construction site noticed the tail of a tiger and halted work. The mosaic was initially covered over with soil at the conclusion of the excavation for lack of funds to conserve and develop the site. The mosaic is now part of the Lod Mosaic Archaeological Center. The floor, with its colorful display of birds, fish, exotic animals and merchant ships, is believed to have been commissioned by a wealthy resident of the city for his private home. The Lod Community Archaeology Program, which operates in ten Lod schools, five Jewish and five Israeli Arab, combines archaeological studies with participation in digs in Lod. Sports The city's major football club, Hapoel Bnei Lod, plays in Liga Leumit (the second division). Its home is at the Lod Municipal Stadium. The club was formed by a merger of Bnei Lod and Rakevet Lod in the 1980s. Two other clubs in the city play in the regional leagues: Hapoel MS Ortodoxim Lod in Liga Bet and Maccabi Lod in Liga Gimel. Hapoel Lod played in the top division during the 1960s and 1980s, and won the State Cup in 1984. The club folded in 2002. A new club, Hapoel Maxim Lod (named after former mayor Maxim Levy) was established soon after, but folded in 2007. Notable people Twin towns-sister cities Lod is twinned with: See also References Bibliography External links |
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[SOURCE: https://en.wikipedia.org/w/index.php?title=OpenAI&action=edit§ion=8] | [TOKENS: 1430] |
Editing OpenAI (section) Copy and paste: – — ° ′ ″ ≈ ≠ ≤ ≥ ± − × ÷ ← → · § Cite your sources: <ref></ref> {{}} {{{}}} | [] [[]] [[Category:]] #REDIRECT [[]] <s></s> <sup></sup> <sub></sub> <code></code> <pre></pre> <blockquote></blockquote> <ref></ref> <ref name="" /> {{Reflist}} <references /> <includeonly></includeonly> <noinclude></noinclude> {{DEFAULTSORT:}} <nowiki></nowiki> <!-- --> <span class="plainlinks"></span> Symbols: ~ | ¡ ¿ † ‡ ↔ ↑ ↓ • ¶ # ∞ ‹› «» ¤ ₳ ฿ ₵ ¢ ₡ ₢ $ ₫ ₯ € ₠ ₣ ƒ ₴ ₭ ₤ ℳ ₥ ₦ ₧ ₰ £ ៛ ₨ ₪ ৳ ₮ ₩ ¥ ♠ ♣ ♥ ♦ 𝄫 ♭ ♮ ♯ 𝄪 © ¼ ½ ¾ Latin: A a Á á À à  â Ä ä Ǎ ǎ Ă ă Ā ā à ã Å å Ą ą Æ æ Ǣ ǣ B b C c Ć ć Ċ ċ Ĉ ĉ Č č Ç ç D d Ď ď Đ đ Ḍ ḍ Ð ð E e É é È è Ė ė Ê ê Ë ë Ě ě Ĕ ĕ Ē ē Ẽ ẽ Ę ę Ẹ ẹ Ɛ ɛ Ǝ ǝ Ə ə F f G g Ġ ġ Ĝ ĝ Ğ ğ Ģ ģ H h Ĥ ĥ Ħ ħ Ḥ ḥ I i İ ı Í í Ì ì Î î Ï ï Ǐ ǐ Ĭ ĭ Ī ī Ĩ ĩ Į į Ị ị J j Ĵ ĵ K k Ķ ķ L l Ĺ ĺ Ŀ ŀ Ľ ľ Ļ ļ Ł ł Ḷ ḷ Ḹ ḹ M m Ṃ ṃ N n Ń ń Ň ň Ñ ñ Ņ ņ Ṇ ṇ Ŋ ŋ O o Ó ó Ò ò Ô ô Ö ö Ǒ ǒ Ŏ ŏ Ō ō Õ õ Ǫ ǫ Ọ ọ Ő ő Ø ø Œ œ Ɔ ɔ P p Q q R r Ŕ ŕ Ř ř Ŗ ŗ Ṛ ṛ Ṝ ṝ S s Ś ś Ŝ ŝ Š š Ş ş Ș ș Ṣ ṣ ß T t Ť ť Ţ ţ Ț ț Ṭ ṭ Þ þ U u Ú ú Ù ù Û û Ü ü Ǔ ǔ Ŭ ŭ Ū ū Ũ ũ Ů ů Ų ų Ụ ụ Ű ű Ǘ ǘ Ǜ ǜ Ǚ ǚ Ǖ ǖ V v W w Ŵ ŵ X x Y y Ý ý Ŷ ŷ Ÿ ÿ Ỹ ỹ Ȳ ȳ Z z Ź ź Ż ż Ž ž ß Ð ð Þ þ Ŋ ŋ Ə ə Greek: Ά ά Έ έ Ή ή Ί ί Ό ό Ύ ύ Ώ ώ Α α Β β Γ γ Δ δ Ε ε Ζ ζ Η η Θ θ Ι ι Κ κ Λ λ Μ μ Ν ν Ξ ξ Ο ο Π π Ρ ρ Σ σ ς Τ τ Υ υ Φ φ Χ χ Ψ ψ Ω ω {{Polytonic|}} Cyrillic: А а Б б В в Г г Ґ ґ Ѓ ѓ Д д Ђ ђ Е е Ё ё Є є Ж ж З з Ѕ ѕ И и І і Ї ї Й й Ј ј К к Ќ ќ Л л Љ љ М м Н н Њ њ О о П п Р р С с Т т Ћ ћ У у Ў ў Ф ф Х х Ц ц Ч ч Џ џ Ш ш Щ щ Ъ ъ Ы ы Ь ь Э э Ю ю Я я ́ IPA: t̪ d̪ ʈ ɖ ɟ ɡ ɢ ʡ ʔ ɸ β θ ð ʃ ʒ ɕ ʑ ʂ ʐ ç ʝ ɣ χ ʁ ħ ʕ ʜ ʢ ɦ ɱ ɳ ɲ ŋ ɴ ʋ ɹ ɻ ɰ ʙ ⱱ ʀ ɾ ɽ ɫ ɬ ɮ ɺ ɭ ʎ ʟ ɥ ʍ ɧ ʼ ɓ ɗ ʄ ɠ ʛ ʘ ǀ ǃ ǂ ǁ ɨ ʉ ɯ ɪ ʏ ʊ ø ɘ ɵ ɤ ə ɚ ɛ œ ɜ ɝ ɞ ʌ ɔ æ ɐ ɶ ɑ ɒ ʰ ʱ ʷ ʲ ˠ ˤ ⁿ ˡ ˈ ˌ ː ˑ ̪ {{IPA|}} This page is a member of 8 hidden categories (help): |
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[SOURCE: https://en.wikipedia.org/wiki/Special:BookSources/978-4909977199] | [TOKENS: 380] |
Contents Book sources This page allows users to search multiple sources for a book given a 10- or 13-digit International Standard Book Number. Spaces and dashes in the ISBN do not matter. This page links to catalogs of libraries, booksellers, and other book sources where you will be able to search for the book by its International Standard Book Number (ISBN). Online text Google Books and other retail sources below may be helpful if you want to verify citations in Wikipedia articles, because they often let you search an online version of the book for specific words or phrases, or you can browse through the book (although for copyright reasons the entire book is usually not available). At the Open Library (part of the Internet Archive) you can borrow and read entire books online. Online databases Subscription eBook databases Libraries Alabama Alaska California Colorado Connecticut Delaware Florida Georgia Illinois Indiana Iowa Kansas Kentucky Massachusetts Michigan Minnesota Missouri Nebraska New Jersey New Mexico New York North Carolina Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Washington state Wisconsin Bookselling and swapping Find your book on a site that compiles results from other online sites: These sites allow you to search the catalogs of many individual booksellers: Non-English book sources If the book you are looking for is in a language other than English, you might find it helpful to look at the equivalent pages on other Wikipedias, linked below – they are more likely to have sources appropriate for that language. Find other editions The WorldCat xISBN tool for finding other editions is no longer available. However, there is often a "view all editions" link on the results page from an ISBN search. Google books often lists other editions of a book and related books under the "about this book" link. You can convert between 10 and 13 digit ISBNs with these tools: Find on Wikipedia See also Get free access to research! Research tools and services Outreach Get involved |
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[SOURCE: https://en.wikipedia.org/wiki/Andesitic] | [TOKENS: 2239] |
Contents Andesite Andesite (/ˈændəzaɪt/) is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende. Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Martian crust. The name andesite is derived from the Andes mountain range, where this rock type is found in abundance. It was first applied by Christian Leopold von Buch in 1826. Description Andesite is an aphanitic (fine-grained) to porphyritic (coarse-grained) igneous rock that is intermediate in its content of silica and low in alkali metals. It has less than 20% quartz and 10% feldspathoid by volume, with at least 65% of the feldspar in the rock consisting of plagioclase. This places andesite in the basalt/andesite field of the QAPF diagram. Andesite is further distinguished from basalt by its silica content of over 52%. However, it is often not possible to determine the mineral composition of volcanic rocks, due to their very fine grain size, and andesite is then defined chemically as volcanic rock with a content of 57% to 63% silica and not more than about 6% alkali metal oxides. This places the andesite in the O2 field of the TAS classification. Basaltic andesite, with a content of 52% to 57% silica, is represented by the O1 field of the TAS classification but is not a distinct rock type in the QAPF classification. Andesite is usually light to dark grey in colour, due to its content of hornblende or pyroxene minerals. but can exhibit a wide range of shading. Darker andesite can be challenging to distinguish from basalt, but a common rule of thumb, used away from the laboratory, is that andesite has a color index less than 35. The plagioclase in andesite varies widely in sodium content, from anorthite to oligoclase, but is typically andesine, in which anorthite makes up about 40 mol% of the plagioclase. The pyroxene minerals that may be present include augite, pigeonite, or orthopyroxene. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals. Alkali feldspar may be present in minor amounts. Andesite is usually porphyritic, containing larger crystals (phenocrysts) of plagioclase formed prior to the extrusion that brought the magma to the surface, embedded in a finer-grained matrix. Phenocrysts of pyroxene or hornblende are also common. These minerals have the highest melting temperatures of the typical minerals that can crystallize from the melt and are therefore the first to form solid crystals. Classification of andesites may be refined according to the most abundant phenocryst. For example, if hornblende is the principal phenocryst mineral, the andesite will be described as a hornblende andesite. Andesitic volcanism Andesite lava typically has a viscosity of 3.5 million cP (3500 Pa⋅s) at 1,200 °C (2,190 °F). This is slightly greater than the viscosity of smooth peanut butter. As a result, andesitic volcanism is often explosive, forming tuffs and agglomerates. Andesite vents tend to build up composite volcanoes rather than the shield volcanoes characteristic of basalt, with its much lower viscosity resulting from its lower silica content and higher eruption temperature. Block lava flows are typical of andesitic lavas from composite volcanoes. They behave in a similar manner to ʻaʻā flows but their more viscous nature causes the surface to be covered in smooth-sided angular fragments (blocks) of solidified lava instead of clinkers. As with ʻaʻā flows, the molten interior of the flow, which is kept insulated by the solidified blocky surface, advances over the rubble that falls off the flow front. They also move much more slowly downhill and are thicker in depth than ʻaʻā flows. Generation of melts in island arcs Though andesite is common in other tectonic settings, it is particularly characteristic of convergent plate margins. Even before the Plate Tectonics Revolution, geologists had defined an andesite line in the western Pacific that separated basalt of the central Pacific from andesite further west. This coincides with the subduction zones at the western boundary of the Pacific Plate. Magmatism in island arc regions comes from the interplay of the subducting plate and the mantle wedge, the wedge-shaped region between the subducting and overriding plates. The presence of convergent margins dominated by andesite is so characteristic of the Earth's unique plate tectonics that the Earth has been described as an "andesite planet". During subduction, the subducted oceanic crust is subjected to increasing pressure and temperature, leading to metamorphism. Hydrous minerals such as amphibole, zeolites, or chlorite (which are present in the oceanic lithosphere) dehydrate as they change to more stable, anhydrous forms, releasing water and soluble elements into the overlying wedge of mantle. Fluxing water into the wedge lowers the solidus of the mantle material and causes partial melting. Due to the lower density of the partially molten material, it rises through the wedge until it reaches the lower boundary of the overriding plate. Melts generated in the mantle wedge are of basaltic composition, but they have a distinctive enrichment of soluble elements (e.g. potassium (K), barium (Ba), and lead (Pb)) which are contributed from sediment that lies at the top of the subducting plate. Although there is evidence to suggest that the subducting oceanic crust may also melt during this process, the relative contribution of the three components (crust, sediment, and wedge) to the generated basalts is still a matter of debate. Basalt thus formed can contribute to the formation of andesite through fractional crystallization, partial melting of crust, or magma mixing, all of which are discussed next. Genesis Intermediate volcanic rocks are created via several processes: To achieve andesitic composition via fractional crystallization, a basaltic magma must crystallize specific minerals that are then removed from the melt. This removal can take place in a variety of ways, but most commonly this occurs by crystal settling. The first minerals to crystallize and be removed from a basaltic parent are olivines and amphiboles. These mafic minerals settle out of the magma, forming mafic cumulates. There is geophysical evidence from several arcs that large layers of mafic cumulates lie at the base of the crust. Once these mafic minerals have been removed, the melt no longer has a basaltic composition. The silica content of the residual melt is enriched relative to the starting composition. The iron and magnesium contents are depleted. As this process continues, the melt becomes more and more evolved eventually becoming andesitic. Without continued addition of mafic material, however, the melt will eventually reach a rhyolitic composition. This produces the characteristic basalt-andesite-rhyolite association of island arcs, with andesite the most distinctive rock type. Partially molten basalt in the mantle wedge moves upwards until it reaches the base of the overriding crust. Once there, the basaltic melt can either underplate the crust, creating a layer of molten material at its base, or it can move into the overriding plate in the form of dykes. If it underplates the crust, the basalt can (in theory) cause partial melting of the lower crust due to the transfer of heat and volatiles. Models of heat transfer, however, show that arc basalts emplaced at temperatures 1100–1240 °C cannot provide enough heat to melt lower crustal amphibolite. Basalt can, however, melt pelitic upper crustal material. In continental arcs, such as the Andes, magma often pools in the shallow crust creating magma chambers. Magmas in these reservoirs become evolved in composition (dacitic to rhyolitic) through both the process of fractional crystallization and partial melting of the surrounding country rock. Over time as crystallization continues and the system loses heat, these reservoirs cool. In order to remain active, magma chambers must have continued recharge of hot basaltic melt into the system. When this basaltic material mixes with the evolved rhyolitic magma, the composition is returned to andesite, its intermediate phase. Evidence of magma mixing is provided by the presence of phenocrysts in some andesites that are not in chemical equilibrium with the melt in which they are found. High-magnesium andesites (boninites) in island arcs may be primitive andesites, generated from metasomatized mantle. Experimental evidence shows that depleted mantle rock exposed to alkali fluids such as might be given off by a subducting slab generates magma resembling high-magnesium andesites. Notable andesite structures Notable stonemasonry structures built with andesite include: Extraterrestrial samples In 2009, researchers revealed that andesite was found in two meteorites (numbered GRA 06128 and GRA 06129) that were discovered in the Graves Nunataks icefield during the US Antarctic Search for Meteorites 2006/2007 field season. This possibly points to a new mechanism to generate andesite crust. Along with basalts, andesites are a component of the Martian crust. The presence of distinctive steep-sided domes on Venus suggests that andesite may have been erupted from large magma chambers where crystal settling could take place. See also References External links Volcanic rocks:Subvolcanic rocks:Plutonic rocks: Picrite basaltPeridotite BasaltDiabase (Dolerite)Gabbro AndesiteMicrodioriteDiorite DaciteMicrogranodioriteGranodiorite RhyoliteMicrograniteGranite |
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File:Moreno Sociogram 2nd Grade.png Summary Licensing File history Click on a date/time to view the file as it appeared at that time. File usage The following 6 pages use this file: Global file usage The following other wikis use this file: |
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[SOURCE: https://en.wikipedia.org/wiki/Prime_Minister_of_Israel] | [TOKENS: 2926] |
Contents Prime Minister of Israel The prime minister of Israel (Hebrew: רֹאשׁ הַמֶּמְשָׁלָה, romanised: Rosh HaMemshala, lit. 'Head of the Government', Hebrew abbreviation: רה״מ; Arabic: رئيس الحكومة, romanised: Ra'īs al-Ḥukūma) is the head of government and chief executive of the State of Israel. Israel is a parliamentary republic with a president as the head of state. The president's powers are largely ceremonial, while the prime minister holds the executive power. The official residence of the prime minister, Beit Aghion, is in Jerusalem. The current prime minister is Benjamin Netanyahu of Likud, the ninth person to hold the position (excluding caretakers). Following an election, the president nominates a member of the Knesset to become prime minister after asking party leaders whom they support for the position. The first candidate the president nominates has 28 days to form a viable government that can command a majority in the Knesset. He then presents a government platform and must receive a vote of confidence from the Knesset to take office. In practice, the prime minister is usually the leader of the largest party in the governing coalition. Since it is all but impossible for one party to win a majority in the Knesset, all Israeli governments have been coalitions between two or more parties. Between 1996 and 2001, the prime minister was directly elected, separately from the Knesset. The prime minister's position is greatly enhanced compared to his counterparts in other parliamentary republics because he is both de jure and de facto chief executive. This is because Basic Law: The Government explicitly vests executive power in the Government, of which the prime minister is the leader. In most other parliamentary republics, the president is at least nominal chief executive, while usually required by convention to act on the advice of the cabinet. History The office of Prime Minister came into existence on 14 May 1948, the date of the Declaration of the Establishment of the State of Israel, when the provisional government was created. David Ben-Gurion, leader of Mapai and head of the Jewish Agency, became Israel's first prime minister. The position became permanent on 8 March 1949, when the first government was formed. Ben-Gurion retained his role until late 1953, when he resigned to settle in the Kibbutz of Sde Boker. He was replaced by Moshe Sharett. However, Ben-Gurion returned in a little under two years to reclaim his position. He resigned for a second time in 1963, breaking away from Mapai to form Rafi. Levi Eshkol took over as head of Mapai and prime minister. He became the first prime minister to head the country under the banner of two parties when Mapai formed the Alignment with Ahdut HaAvoda in 1965. In 1968 he also became the only party leader to command an absolute majority in the Knesset, after Mapam and Rafi merged into the Alignment, giving it 63 seats in the 120-seat Knesset. On 26 February 1969, Eshkol became the first prime minister to die in office. He was temporarily replaced by Yigal Allon, whose stint lasted less than a month, as the party persuaded Golda Meir to return to political life and become prime minister in March 1969. Meir was Israel's first woman prime minister, and the third in the world (after Sirimavo Bandaranaike and Indira Gandhi). Meir resigned in 1974 after the Agranat Commission published its findings on the Yom Kippur War, even though it had absolved her of blame. Yitzhak Rabin took over, though he also resigned towards the end of the eighth Knesset's term following a series of scandals. Those included the suicide of Housing Minister Avraham Ofer after police began investigating allegations that he had used party funds illegally, and the affair involving Asher Yadlin (the governor-designate of the Bank of Israel), who was sentenced to five years in prison for having accepted bribes. Rabin's wife, Leah, was also found to have had an overseas bank account, which was illegal in Israel at the time. Menachem Begin became the first right-wing prime minister when his Likud won the 1977 elections, and retained the post in the 1981 elections. He resigned in 1983 for health reasons, passing the reins of power to Yitzhak Shamir. After the 1984 elections had proved inconclusive with neither the Alignment nor Likud able to form a government, a national unity government was formed with a rotating prime ministership – Shimon Peres took the first two years, and was replaced by Shamir midway through the Knesset term. Although the 1988 elections produced another national unity government, Shamir was able to take the role alone. Peres made an abortive bid to form a left-wing government in 1990, but failed, leaving Shamir in power until 1992. Rabin became prime minister for the second time when he led Labour to victory in the 1992 elections. After his assassination on 4 November 1995, Peres took over as prime minister. During the thirteenth Knesset (1992–1996) it was decided to hold a separate ballot for prime minister modelled after American presidential elections. This system was instituted in part because the Israeli electoral system makes it all but impossible for one party to win a majority. While only two parties—Mapai/Labour and Likud—had ever led governments, the large number of parties or factions in a typical Knesset usually prevents one party from winning the 61 seats needed for a majority. In 1996, when the first such election took place, the outcome was a surprise win for Benjamin Netanyahu after election polls predicted that Peres was the winner. However, in the Knesset election held at the same time, Labour won more votes than any other party (27%). Thus Netanyahu, despite his theoretical position of power, needed the support of the religious parties to form a viable government. Ultimately Netanyahu failed to hold the government together, and early elections for both prime minister and the Knesset were called in 1999. Although five candidates intended to run, the three representing minor parties (Benny Begin of Herut – The National Movement, Azmi Bishara of Balad, and Yitzhak Mordechai of the Centre Party) dropped out before election day, and Ehud Barak beat Netanyahu in the election. However, the new system again appeared to have failed; although Barak's One Israel alliance (an alliance of Labour, Gesher, and Meimad) won more votes than any other party in the Knesset election, they garnered only 26 seats, the lowest ever by a winning party or alliance. Barak needed to form a coalition with six smaller parties to form a government. In early 2001, Barak resigned following the outbreak of the al-Aqsa Intifada. However, the government was not brought down, and only elections for prime minister were necessary. In the election itself, Ariel Sharon of Likud comfortably beat Barak, taking 62.4% of the vote. However, because Likud only had 21 seats in the Knesset, Sharon had to form a national unity government. Following Sharon's victory, it was decided to do away with separate elections for prime minister and return to the previous system. The 2003 elections were carried out in the same manner as prior to 1996. Likud won 38 seats, the highest by a party for over a decade, and as party leader Sharon was duly appointed Prime Minister. However, towards the end of his term and largely as a result of the deep divisions within Likud over Israel's unilateral disengagement plan, Sharon broke away from his party to form Kadima, managing to maintain his position as prime minister and also becoming the first prime minister not to be a member of either Labour or Likud (or their predecessors). However, he suffered a stroke in January 2006, in the midst of election season, leading Ehud Olmert to become acting prime minister in the weeks leading to the elections. He was voted by the cabinet to be interim prime minister just after the 2006 elections, when Sharon had reached 100 days of incapacitation. He thus became Israel's third interim prime minister, only days before forming his own new government as the official Prime Minister of Israel. In 2008, amid accusations of corruption and challenges from his own party, Olmert resigned. However, his successor Tzipi Livni was unable to form a coalition government. In the election in the following year, while Kadima won the most seats, it was the Likud leader Benjamin Netanyahu who was given the task of forming a government. He was able to do so, thus beginning his second term as Prime Minister of Israel. In the 2013 election, the Likud Yisrael Beiteinu alliance emerged as the largest faction. After forming a coalition, Netanyahu secured his third prime ministership. In 2015, Netanyahu managed to stay in power. Multiple disagreements with his coalition members led to the 2019–2022 Israeli political crisis. In 2021, Naftali Bennett became prime minister. He was succeeded in July 2022 by his coalition partner, Yair Lapid. In December 2022, Benjamin Netanyahu returned to the prime ministership, as a result of the previous month's election. Order of succession If the prime minister dies in office, the cabinet chooses an interim prime minister to run the government until a new government is placed in power. Yigal Allon served as interim prime minister following Levi Eshkol's death, as did Shimon Peres following the assassination of Yitzhak Rabin. According to Israeli law, if a prime minister is temporarily incapacitated rather than dies (as was the case following Ariel Sharon's stroke in early 2006), power is transferred to the acting prime minister, until the prime minister recovers (Ehud Olmert took over from Sharon), for up to 100 days. If the prime minister is declared permanently incapacitated, or that period expires, the president of Israel oversees the process of assembling a new governing coalition, and in the meantime the acting prime minister or other incumbent minister is appointed by the cabinet to serve as interim prime minister. In the case of Sharon, elections were already due to occur within 100 days of the beginning of his coma; thus, the post-election coalition-building process pre-empted the emergency provisions for the selection of a new prime minister. Nevertheless, Olmert was appointed interim prime minister on 16 April 2006, after the elections, just days before he formed a government on 4 May 2006, becoming the official prime minister. Aside from the position of Acting Prime Minister, there are also vice prime ministers and deputy prime ministers. The interim prime minister (Hebrew: ראש הממשלה בפועל, Rosh HaMemshala Ba-foal lit. "prime minister de facto") is appointed by the government if the incumbent is dead or permanently incapacitated, or if his tenure was ended due to a criminal conviction. Israeli law distinguishes the terms acting prime minister (מלא מקום ראש הממשלה), filling in for the incumbent prime minister, temporarily, and acting in the incumbent's office, while the incumbent is in office, and an interim prime minister in office. Only if the incumbent prime minister becomes temporarily incapacitated will the acting prime minister act in the incumbent's office and will be standing in for him for up to 100 consecutive days, while the incumbent is in office. Legally, the "100 consecutive days" limit, in the language of the law, only stipulates that the incumbent then is deemed to be permanently incapacitated and that the limited time for an acting prime minister to act in the incumbent's office is over. In 2006, Ehud Olmert, after standing in for Prime Minister Sharon for 100 consecutive days, as acting prime minister, did not automatically assume office as an interim prime minister. The government voted to appoint him, and in addition, he was also a member of prime minister's party, which enabled them to appoint him to the role. Shimon Peres was the foreign minister when Prime Minister Yitzhak Rabin was assassinated, and was voted unanimously to assume office as an interim prime minister until a new Government would be placed in power (that he later formed by himself). Yigal Allon was also voted to be the interim prime minister after Prime Minister Levi Eshkol suddenly died and served until Golda Meir formed her government. Both the interim and acting prime ministers' authorities are identical to those of a prime minister, with the exception of not having the authority to dissolve the Knesset. An 'interim government' (Hebrew: ממשלת מעבר, Memshelet Ma'avar lit. "transitional government") is the same government, having been changed in their legal status, after the death, resignation, permanent incapacitation, or criminal conviction of the prime minister, as well as after the prime minister's request to dissolve the Knesset (Israeli parliament) was published through the president's decree, or after it was defeated by a motion of no confidence (these actions are regarded by the law as "the Government shall be deemed to have resigned"), or after election and before the forming of a new government. Prime Minister's residence Since 1974, the official residence of the prime minister is Beit Aghion, at the corner of Balfour and Smolenskin streets in Rehavia, Jerusalem. List of prime ministers of Israel See also References Further reading External links |
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Contents New France New France[d] was the territory colonized by France in North America, beginning with the exploration of the Gulf of Saint Lawrence by Jacques Cartier in 1534 and ending with the cession of New France to Great Britain and Spain in 1763 under the Treaty of Paris. A vast viceroyalty, New France consisted of five colonies at its peak in 1712, each with its own administration: Canada, the most developed colony, which was divided into the districts of Quebec (around what is now called Quebec City), Trois-Rivières, and Montreal; Hudson Bay; Acadia in the northeast; Terre-Neuve on the island of Newfoundland; and Louisiana. It extended from Newfoundland to the Canadian Prairies and from Hudson Bay to the Gulf of Mexico, including all the Great Lakes of North America. The continent-traversing Saint Lawrence and Mississippi rivers were means of carrying French influence through much of North America. In the 16th century, the lands were used primarily to extract natural resources, such as furs, through trade with the various indigenous peoples. In the seventeenth century, successful settlements began in Acadia and in Quebec. In the 1713 Treaty of Utrecht, France ceded to Great Britain its claims over mainland Acadia, Hudson Bay, and Newfoundland. France established the colony of Île Royale on Cape Breton Island, where they built the Fortress of Louisbourg. The population rose slowly but steadily. In 1754, New France's population consisted of 10,000 Acadians, 55,000 Canadiens, and about 4,000 settlers in upper and lower Louisiana; 69,000 in total. The British expelled the Acadians in the Great Upheaval from 1755 to 1764, and their descendants are dispersed in the Maritime provinces of Canada and in Maine and Louisiana, with small populations in Chéticamp, Nova Scotia, and the Magdalen Islands. Some also went to France. After the Seven Years' War (which included the French and Indian War in America), France ceded the rest of New France to Great Britain and Spain in the Treaty of Paris of 1763, although fishing rights around Newfoundland were retained. To assist with those fishing rights, Great Britain returned the islands of Saint Pierre and Miquelon, which had been lost in 1713. Britain acquired Canada, Acadia, and French Louisiana east of the Mississippi River, except for the Île d'Orléans, which was granted to Spain with the territory to the west. In 1800, Spain returned its portion of Louisiana to France under the secret Treaty of San Ildefonso, and Napoleon Bonaparte sold it to the United States in the Louisiana Purchase of 1803, permanently ending French colonial efforts on the North American mainland. New France eventually became absorbed within the United States and Canada, with the only vestige of French rule being the tiny islands of Saint Pierre and Miquelon, an overseas collectivity of France, although Quebec remains predominantly French-speaking. In the United States, the legacy of New France includes numerous place names as well as small pockets of French-speaking communities. Settlements of New France New France had five colonies or territories, each with its own administration: Canada (the Great Lakes region, the Ohio Valley, and the St. Lawrence River Valley), Acadia (the Gaspé Peninsula, New Brunswick, Nova Scotia, St. John's Island, and Île Royale-Cape Breton), Hudson Bay (and James Bay), Terre-Neuve (south Newfoundland), and Louisiana. The 1715 Treaty of Utrecht resulted in the relinquishing of French claims to mainland Acadia, the Hudson Bay and Newfoundland, and the establishment of the colony of Île Royale, now called Cape Breton Island, where the French built the Fortress of Louisbourg. The European population grew slowly under French rule, thus remained relatively low as growth was largely achieved through natural births, rather than by immigration. Most of the French were farmers, and the rate of natural increase among the settlers themselves was very high. The women had about 30 per cent more children than their counterparts who remained in France. Yves Landry says, "Canadians had an exceptional diet for their time." The 1666 census of New France was the first census conducted in North America. It was organized by Jean Talon, the first Intendant of New France, between 1665 and 1666. According to Talon's census there were 3,215 people in New France, comprising 538 separate families. The census showed a great difference in the number of men at 2,034 versus 1,181 women. The French government sought to rectify this over the next few years by sending approximately 800 unmarried women, known as the Filles du Roi ("King's Daughters"), to the colony. By the early 1700s, the New France settlers were well established along the Saint Lawrence River and Acadian Peninsula with a population around 15,000-16,000. The first population figures for Acadia are from 1671, which enumerated only 450 people. After the Treaty of Utrecht in 1713, New France began to prosper. Industries such as fishing and farming, which had failed under Talon, began to flourish. A "King's Highway" (Chemin du Roy) was built between Montreal and Quebec to encourage faster trade. The shipping industry also flourished as new ports were built and old ones were upgraded. The number of colonists greatly increased. By 1720, Canada had become a self-sufficient colony with a population of 24,594. Mainly due to natural increase and modest immigration from Northwest France (Brittany, Normandy, Île-de-France, Poitou-Charentes and Pays de la Loire) the population of Canada increased to 55,000 according to the last French census of 1754. This was an increase from 42,701 in 1730. By 1765, the population approached 70,000. By 1714, the Acadian population had expanded to over 2,500, and by the end of the 1750s it had reached about 13,000. This was mostly from natural increase rather than immigration that affected other French settlements. The European population of Louisiana is estimated at 5,000 by the 1720s. However, by the mid-1730s the colony had suffered the loss of 2,000 French settlers, though it added African slaves. Enslaved men, women and children represented approximately 65 percent of the 6,000 non-indigenous population of Louisiana by the end of French rule. History Around 1523, the Florentine navigator Giovanni da Verrazzano convinced King Francis I to commission an expedition to find a western route to Cathay (China). Late that year, Verrazzano set sail in Dieppe, crossing the Atlantic on a small caravel with 50 men. After exploring the coast of the present-day Carolinas early the following year, he headed north along the coast, eventually anchoring in the Narrows of New York Bay. The first European to visit the site of present-day New York, Verrazzano named it Nouvelle-Angoulême in honour of the king, the former count of Angoulême. Verrazzano's voyage convinced the king to seek to establish a colony in the newly discovered land. Verrazzano gave the names Francesca and Nova Gallia to that land between New Spain (Mexico) and English Newfoundland. In 1534, Jacques Cartier planted a cross in the Gaspé Peninsula and claimed the land in the name of King Francis I.[failed verification] It was the first province of New France. The first settlement of 400 people, Fort Charlesbourg-Royal (present-day Quebec City), was attempted in 1541 but lasted only two years. French fishing fleets continued to sail to the Atlantic coast and into the St. Lawrence River, making alliances with Canadian First Nations that became important once France began to occupy the land. French merchants soon realized the St. Lawrence region was full of valuable fur-bearing animals, especially the beaver, which were becoming rare in Europe. Eventually, the French crown decided to colonize the territory to secure and expand its influence in America.[citation needed] Acadia and Canada (New France) were inhabited by indigenous nomadic Algonquian peoples and sedentary Iroquoian peoples. These lands were full of unexploited and valuable natural resources, which attracted all of Europe. By the 1580s, French trading companies had been set up, and ships were contracted to bring back furs. Much of what transpired between the indigenous population and their European visitors around that time is not known, for lack of historical records. Other attempts at establishing permanent settlements were also failures. In 1598, a French trading post was established on Sable Island, off the coast of Acadia, but was unsuccessful. In 1600, a trading post was established at Tadoussac, but only five settlers survived the winter. In 1604, King Henri IV sponsored Pierre Dugua, Sieur de Mons to found a settlement in New France. It was initially located at Île-Saint-Croix in modern-day Maine, which was moved to Port-Royal, Acadia, in modern day Nova Scotia, in 1605. Early participants in Port Royal included Samuel de Champlain and Jean de Biencourt de Poutrincourt et de Saint-Just. The first seigneury in New France, was granted to Poutrincourt in 1604, who actively promoted its development. By 1607, New France's first grist mill was established on the seigneury. Poutrincourt invited Louis Hébert to Port Royal where he pioneered many European agricultural practices in the New World, including viticulture, arboriculture and cereal farming, before relocating to Quebec in 1617. The principal structure of early Port Royal, the habitation, was destroyed in 1613, after which settlers moved to other nearby locations. Port Royal was the first successful attempt by Europeans to establish a permanent settlement in New France. Although the French, notably Charles de Saint-Étienne de la Tour, remained active after 1613, official support for Port Royal resumed only in 1632. Control of Port Royal and Acadia shifted between Britain and France until Britain permanently took it in 1712. The Acadians remained dominant until their deportation began in 1755. Allowed to return in 1764 if they swore allegiance, Acadians today form a significant French-speaking community in New Brunswick and Nova Scotia. In 1608, King Henry IV sponsored Pierre Dugua, Sieur de Mons and Samuel de Champlain as founders of the city of Quebec with 28 men. This was the second permanent French settlement in the colony of Canada. Colonization was slow and difficult. Many settlers died early because of harsh weather and diseases. In 1630, there were only 103 colonists living in the settlement, but by 1640, the population had reached 355. Champlain allied himself with the Algonquin and Montagnais peoples in the area, who were at war with the Iroquois, as soon as possible. In 1609, Champlain and two French companions accompanied his Algonquin, Montagnais, and Huron allies south from the St. Lawrence Valley to Lake Champlain. He participated decisively in a battle against the Iroquois there, killing two Iroquois chiefs with the first shot of his arquebus. This military engagement against the Iroquois solidified Champlain's status with New France's Huron and Algonquin allies, enabling him to maintain bonds essential to New France's interests in the fur trade. Champlain also arranged to have young French men live with local indigenous people, to learn their language and customs and help the French adapt to life in North America. These coureurs des bois ("runners of the woods"), including Étienne Brûlé, extended French influence south and west to the Great Lakes and among the Huron tribes who lived there. Ultimately, for the better part of a century, the Iroquois and French clashed in a series of attacks and reprisals. During the first decades of the colony's existence, only a few hundred French people lived there, while the English colonies to the south were much more populous and wealthy. Cardinal Richelieu, adviser to Louis XIII, wished to make New France as significant as the English colonies. In 1627, Richelieu founded the Company of One Hundred Associates to invest in New France, promising land parcels to hundreds of new settlers and to turn Canada into an important mercantile and farming colony. He named Champlain as the Governor of New France and forbade non-Catholics to live there. Consequently, any Protestant emigrants to New France were forced to convert to Catholicism, prompting many of them to relocate to the English colonies instead. The Catholic Church, and missionaries such as the Recollets and the Jesuits, became firmly established in the territory. Richelieu also expanded the seigneurial system from its beginnings at Port-Royal. This was a semi-feudal system of farming based on ribbon farms that remained a characteristic feature of the St. Lawrence valley until the 19th century. While Richelieu's efforts did little to increase the French presence in New France, they did pave the way for the success of later efforts. Simultaneously, during the Anglo-French War (1627–1629) the English colonies to the south began raiding the St. Lawrence Valley, Champlain surrendered Quebec on 19 July 1629. The British held New France with Kirke as governor until 1632, when Treaty of Saint-Germain-en-Laye (1632) was signed on March 29, 1632, which returned New France (Quebec, Acadia and Cape Breton Island) to French control. Champlain returned to Canada that year and requested that Sieur de Laviolette found another trading post at Trois-Rivières, which Laviolette did in 1634. Champlain died in 1635. On 23 September 1646, under the command of Pierre LeGardeur, Le Cardinal arrived to Quebec with Jules (Gilles) Trottier II and his family. Le Cardinal, commissioned by the Communauté des Habitants, had arrived from La Rochelle, France. Communauté des Habitants at the time of Trottier traded fur primarily. On 4 July 1646, by Pierre Teuleron, sieur de Repentigny, granted Trottier land in La Rochelle to build and develop New France, under the authorization Jacques Le Neuf de la Poterie. In 1650, New France had seven hundred colonists and Montreal had only a few dozen settlers. Because the First Nations people did most of the work of beaver hunting, the company needed few French employees. The sparsely populated New France almost fell to hostile Iroquois forces completely as well. In 1660, settler Adam Dollard des Ormeaux led a Canadian and Huron militia against a much larger Iroquois force; none of the Canadians survived, although they did turn back the Iroquois invasion. In 1627, Quebec had only eighty-five French colonists and was easily overwhelmed two years later when three English privateers plundered the settlement. In 1663, New France finally became more secure when Louis XIV made it a royal province, taking control away from the Company of One Hundred Associates. In the same year the Société Notre-Dame de Montréal ceded its possessions to the Seminaire de Saint-Sulpice. The Crown paid for transatlantic passages and offered other incentives to those willing to move to New France as well, after which the population of New France grew to three thousand. In 1665, Louis XIV sent a French garrison, the Carignan-Salières Regiment, to Quebec. The colonial government was reformed along the lines of the government of France, with the Governor General and Intendant subordinate to the French Minister of the Marine. In 1665, Jean Talon Minister of the Marine accepted an appointment from Jean-Baptiste Colbert as the first Intendant of New France. These reforms limited the power of the Bishop of Quebec, who had held the greatest amount of power after the death of Champlain. Talon tried reforming the seigneurial system by forcing the seigneurs to reside on their land and limiting the size of the seigneuries, intending to make more land available to new settlers. Talon's attempts failed since very few settlers arrived and the various industries he established failed to surpass the importance of the fur trade. The first settler, brought to Quebec by Champlain, was the apothecary Louis Hébert and his family of Paris. They expressly came to settle and remain in New France so as to make the settlement viable. Waves of recruits came in response to the requests for men with specific skills, e.g., farmers, architects, and blacksmiths. At the same time, the government encouraged intermarriages with the indigenous peoples and welcomed indentured servants, or engagés sent to New France. As couples married, cash incentives to have large families were put in place and proved effective. To further strengthen the nascent France's colonial empire, Louis XIV sponsored single women, virtuous, physically fit, and aged between 15 and 30 years, known as the King's Daughters, or, in French, les filles du roi, to move to New France. The King paid for their passage and granted goods or money as their dowries upon their marriage to single settlers. Approximately 800 women, primarily from the impoverished Parisian, Norman, and West-Central families, relocated during 1663–1673. By 1672, the population of New France had risen to 6,700 people, a marked increase from the population of 3,200 people in 1663. This rapid demographic growth was predicated both on the high demand for children and on the ready supply of natural resources to support them. According to Landry, "Canadians had an exceptional diet for their time. This was due to the natural abundance of meat, fish, and pure water; the good food conservation conditions during the winter; and an adequate wheat supply in most years." Consequently, colonial women bore about 30% more children than comparable women in France. Besides household duties, some women participated in the fur trade, the major source of money in New France. They worked at home alongside their husbands or fathers as merchants, clerks, and provisioners. Some were widows who took over their husbands' roles. Some even became independent and active entrepreneurs. The French extended their territorial claim to the south and to the west of the American colonies late in the 17th century, naming it for King Louis XIV, as La Louisiane. In 1682, René-Robert Cavelier, Sieur de La Salle explored the Ohio River Valley and the Mississippi River Valley, and he claimed the entire territory for France as far south as the Gulf of Mexico. La Salle attempted to establish the first southern colony in the new territory in 1685, but inaccurate maps and navigational issues led him to instead establish his Fort Saint Louis in what is now Texas. The colony was devastated by disease, and the surviving settlers were killed in 1688, in an attack by the area's indigenous population. Other parts of Louisiana were settled and developed with success, such as New Orleans and southern Illinois, leaving a strong French influence in these areas long after the Louisiana Purchase. Many strategic forts were built there, under the orders of Governor Louis de Buade de Frontenac. Forts were also built in the older portions of New France that had not yet been settled. Many of these forts were garrisoned by the Troupes de la Marine, the only regular soldiers in New France between 1683 and 1755. The conquest of New France (French: La Conquête) was the military conquest of New France by Great Britain during the French and Indian War. It started with a British campaign in 1758 and ended with the region being put under a British military regime between 1760 and 1763. Britain's acquisition of the New France colony of Canada, which the Kingdom of France had established in 1535, became official with the 1763 Treaty of Paris that concluded the Seven Years' War. The term is usually used when discussing the impact of the British conquest on the 70,000 French inhabitants, as well as on the First Nations. At issue in popular and scholarly debate ever since is the British treatment of the French settler population along with the long-term historical impacts of the conquest. Fur trade and economy According to the staples thesis, the economic development of New France was marked by the emergence of successive economies based on staple commodities, each of which dictated the political and cultural settings of the time. During the 16th and early 17th centuries New France's economy was heavily centered on its Atlantic fisheries. This would change in the later half of the 17th and 18th centuries as French settlement penetrated further into the continental interior. Here French economic interests would shift and concentrate itself on the development of the North American fur trade. It would soon become the new staple good that would strengthen and drive New France's economy, in particular that of Montreal, for the next century. The trading post of Ville-Marie, established on the current island of Montreal, quickly became the economic hub for the French fur trade. It achieved this in great part due to its particular location along the St. Lawrence River. From here a new economy emerged, one of size and density that provided increased economic opportunities for the inhabitants of New France. In December 1627 the Company of New France was recognized and given commercial rights to the gathering and export of furs from French territories. By trading with various indigenous populations and securing the main markets its power grew steadily for the next decade. As a result, it was able to set specific price points for furs and other valuable goods, often doing so to protect its economic hegemony over other trading partners and other areas of the economy. The fur trade itself was based on a commodity of small bulk but high value. Because of this it managed to attract increased attention and/or input capital that would otherwise be intended for other areas of the economy. The Montreal area witnessed a stagnant agricultural sector; it remained for the most part subsistence orientated with little or no trade purposes outside of the French colony. This was a prime example of the handicapping effect the fur trade had on its neighbouring areas of the economy. Nonetheless, by the beginning of the 1700s, the economic prosperity the fur trade stimulated slowly transformed Montreal. Economically, it was no longer a town of small traders or of fur fairs but rather a city of merchants and of bright lights. The primary sector of the fur trade, the act of acquiring and the selling of the furs, quickly promoted the growth of complementary second and tertiary sectors of the economy. For instance a small number of tanneries was established in Montreal as well as a larger number of inns, taverns and markets that would support the growing number of inhabitants whose livelihood depended on the fur trade. Already by 1683 there were well over 140 families and there may have been as many as 900 people living in Montreal. The founding of John Law's Company in 1717, once again highlighted the economic importance of the fur trade. This merchant association, like its predecessor the Compagnie des Cent Associés, regulated the fur trade to the best of its abilities imposing price points, supporting government sale taxes and combating black market practices. However, by the middle half of the 18th century the fur trade was in a slow decline. The natural abundance of furs had passed and it could no longer meet market demand. This eventually resulted in the repeal of the 25 percent sales tax that had previously aimed at curbing the administrative costs New France had accumulated. In addition, dwindling supply increased black market trading. A greater number of indigenous groups and fur traders began circumventing Montreal and New France altogether; many began trading with either British or Dutch merchants to the south. By the end of French rule in New France in 1763, the fur trade had significantly lost its importance as the key staple good that supported much of New France's economy for more than the last century. Even so, it did serve as the fundamental force behind the establishment and vast growth of Montreal and the French colony. The coureurs des bois were responsible for starting the flow of trade from Montreal, carrying French goods into upper territories while indigenous people were bringing down their furs. The coureurs traveled with intermediate trading tribes, and found that they were anxious to prevent French access to the more distant fur-hunting tribes. Still, the coureurs kept thrusting outwards using the Ottawa River as their initial step upon the journey and keeping Montreal as their starting point. The Ottawa River was significant because it offered a route that was practical for Europeans, by taking the traders northward out of the territory dominated by the Iroquois. It was for this reason that Montreal and the Ottawa River was a central location of indigenous warfare and rivalry. Montreal faced difficulties by having too many coureurs out in the woods. The furs coming down were causing an oversupply on the markets of Europe. This challenged the coureurs trade because they so easily evaded controls, monopolies, and taxation, and additionally because the coureurs trade was held to debauch both French and various indigenous groups. The coureur debauched Frenchmen by accustoming them to fully live with indigenous, and indigenous by trading on their desire for alcohol. The issues caused a great rift in the colony, and in 1678, it was confirmed by a General Assembly that the trade was to be made in public so as to better assure the safety of the indigenous population. It was also forbidden to take spirits inland to trade with indigenous groups. However, these restrictions on the coureurs, for a variety of reasons, never worked. The fur trade remained dependent on spirits, and increasingly in the hands of the coureurs who journeyed north in search of furs. As time passed, the Coureurs des bois were partially replaced by licensed fur trading endeavors, and the main canoe travel workers of those endeavors were called voyageurs. The French and Algonquins first encountered one another in 1603 after Samuel de Champlain established France's first permanent North American settlement along the St. Lawrence River. In 1610, the Algonquins continued to solidify their relations with the French by guiding Étienne Brûlé into the interiors of Canada. The relationship between the Iroquois and the French first began in 1609, when Samuel De Champlain engaged in battle against the Iroquois. Champlain travelled from the St. Lawrence Valley, accompanied by his Algonquin, Montagnais, and Huron allies, and managed to kill three Iroquoian chiefs on Lake Champlain with the first shots of his arquebus. Subsequently, the two factions (Iroquois and French) were constantly at war with one another until the Great Peace of Montréal in 1701. The French were interested in exploiting the land through the fur trade as well as the timber trade later on. Despite having tools and guns, the French settlers were dependent on Indigenous people to survive in the difficult climate in this part of North America. Many settlers did not know how to survive through the winter; the Indigenous people showed them how to survive in the New World. They showed the settlers how to hunt for food and to use the furs for clothing that would protect them during the winter months. Modern historians have highlighted that despite largely functional relations with indigenous peoples, administrators in France viewed co-operation as a wholly irritating task. Geographically removed from the colonies, Parisian courtiers viewed indigenous peoples as 'sauvages', often criticising New French officials for even interacting with nations. As the fur trade became the dominant economy in the New World, French voyageurs, trappers and hunters often married or formed relationships with Indigenous women. This allowed the French to develop relations with their wives' Indigenous nations, which in turn provided protection and access to their hunting and trapping grounds. One specific Indigenous group borne of these relationships are the Métis people, who are descendants of marriages between French men and Indigenous women. Their name originates from an old French term for “person of mixed parentage.” At the beginning of the fur trade, these relationships were encouraged by the French as a way to encourage the First Nations to adopt French culture and solidify alliances, but as the Métis began to emerge as an independent culture around the 1700s, it began to be discouraged by the French. Many Métis families moved to western Canada in response to this, as well as for other reasons, such as fur trading opportunities. One major settlement at this time was in the Red River Valley, strategically placed in a significant area for the fur trade. This was the origin of the modern Métis nation, which was legally recognized by modern Canada as a protected Indigenous group in the Constitution Act, 1982. Its prior legal history has its roots in acts such as the Manitoba Act, 1870, which began to recognize the Métis nation as a separate group with various rights and protections, but was not supported by the vast majority of Métis as it removed many from land that was rightfully theirs. The fur trade benefited Indigenous people as well. They traded furs for metal tools and other European-made items that made their lives easier. Tools such as knives, pots and kettles, nets, firearms and hatchets improved the general welfare of indigenous peoples. At the same time, while everyday life became easier, some traditional ways of doing things were abandoned or altered, and while Indigenous people embraced many of these implements and tools, they also were exposed to less vital trade goods, such as alcohol and sugar, sometimes with deleterious effects. The Iroquois, like most tribes, began to rely on the importation of European goods, like firearms, which contributed significantly to a decrease in the beaver population of the Hudson Valley. This decline resulted in the fur trade moving further north, along the St. Lawrence River. Since Henry Hudson had claimed Hudson Bay, and the surrounding lands for England in 1611, English colonists had begun expanding their boundaries across what is now the Canadian north beyond the French-held territory of New France. In 1670, King Charles II of England issued a charter to Prince Rupert and "the Company of Adventurers of England trading into Hudson Bay" for an English monopoly in harvesting furs in Rupert's Land, a portion of the land draining into Hudson Bay. This is the start of the Hudson's Bay Company, ironically aided by French coureurs des bois, Pierre-Esprit Radisson and Médard des Groseilliers, frustrated with French license rules. Now both France and England were formally in the Canadian fur trade. The major commercial importance of the Louisiana Purchase territory was the Mississippi River. New Orleans, the largest and most important city in the territory, was the most commercial city in the United States until the Civil War, with most jobs there being related to trade and shipping; there was little manufacturing. The first commercial shipment to come down the Mississippi River was of deer and bear hides in 1705. The area, always loosely defined in those early times of European claims and settlements, extended as far east as the city that is now Mobile, Alabama, begun by French settlers in 1702. The French (later Spanish) Louisiana Territory was owned by France for a number of years before the money-losing territory was transferred to French banker Antoine Crozat in 1713 for 15 years. After losing four times his investment, Crozat gave up his charter in 1717. Control of Louisiana and its 700 inhabitants was given to the Company of the Indies in 1719. The company conducted a major settlement program by recruiting European settlers to locate in the territory. Unemployed persons, convicts and prostitutes were also sent to the Louisiana Territory. After the bankruptcy of the company in 1720, control was returned to the king. Louis XV saw little value in Louisiana, and to compensate Spain for its losses in the Seven Years' War, he transferred Louisiana to his cousin Charles III in 1762. Louisiana remained under the control of Spain until it was demanded to be turned over to France by Napoleon. Although Louisiana was property of France by the Third Treaty of San Ildefonso in 1800, Louisiana continued to be administered by Spain until the Louisiana Purchase in 1803. Following the American acquisition of the territory, its population tripled between 1803 and Louisiana statehood in 1812. Religion Before the arrival of European colonists and explorers, First Nations followed a wide array of mostly animistic religions. As of 1607, official support for the first settlement at Port Royal was conditional based on efforts to convert the local First Nations people to Christianity. The French who later settled along the shores of the Saint Lawrence River, specifically Catholics, including a number of Jesuits dedicated to converting the indigenous population; an effort that eventually proved successful. Starting from 1627 in Quebec and 1659 in Acadia, all other forms of Christianity other than Roman Catholicism were forbidden to be worshipped or taught in New France and only French-born Roman Catholics were allowed to immigrate. This put an end to religious tolerance in the colony, notwithstanding the fact that both Port Royal and Quebec City were both founded by protestant Huguenot Pierre Dugua. After 1610, Dugua was banished from the French court due to his protestant faith and could only be represented through Champlain. As a result of official policy, the Catholic Church became the dominant force in New France. In 1642, they sponsored a group of settlers, led by Paul Chomedey de Maisonneuve, who founded Ville-Marie, precursor to present-day Montreal, farther up the St. Lawrence. Throughout the 1640s, Jesuit missionaries penetrated the Great Lakes region and converted many of the Huron. The missionaries came into conflict with the Iroquois, who frequently attacked Montreal. The presence of Jesuit missionaries in Huron society was nonnegotiable. The Huron relied on French goods to facilitate life and warfare. Because the French would refuse trade to all indigenous societies that denied relations with missionaries, the Huron had more of a propensity towards Christian conversion. The Huron heavily relied on European goods to perform burial ceremonies known as The Huron Feast of the Dead. Trading with the French allowed for larger amounts of decorative goods to be buried during ceremonies as opposed to only a bare minimum. With the growing epidemics and high number of deaths, the Huron could not afford to lose relations with the French, fearing to anger their ancestors. Jesuit missionaries explored the Mississippi River, including the Illinois Country. Father Jacques Marquette and explorer Louis Jolliet traveled in a small party, starting from Green Bay down the Wisconsin River to the Mississippi River, communicating with the tribes they met en route. Although Spanish trade goods had reached most of the indigenous peoples, these were the first Frenchmen to connect in the area named for the Illinois, including the Kaskaskia. They kept detailed records of what they saw and the people they met, sketching what they could, and mapped the Mississippi River in 1673. Their travels were described as first contacts with the indigenous peoples, though evidence of contact with Spanish from the south was clear. Subsequent to the arrival of French children in Quebec in 1634, measles was also brought along with them, which quickly spread among the indigenous peoples. Jesuit priest Jean de Brébeuf described the symptoms as being severe. Brebeuf stated that the fearlessness of the indigenous peoples towards death upon this disease made them perfect candidates for conversion to Christianity. The indigenous peoples believed that if they did not convert to Christianity, they would be exposed to the evil magic of the priests that caused the illness. Jesuit missionaries were troubled by the absence of patriarchy in indigenous communities. Indigenous women were highly regarded within their societies and participated in political and military decisions. Jesuits attempted to eliminate the matriarchy and shift the powers of men and women to accommodate those of European societies. "In France, women are to be obedient to their masters, their husbands." Jesuits would attempt to justify this to the indigenous women in hopes to enlighten them on proper European behavior. In response, Indigenous women grew worrisome of the presence of these missionaries fearing they would lose power and freedom within their communities. By 1649, both the Jesuit mission and the Huron society were almost destroyed by Iroquois invasions (see Canadian Martyrs). In 1653, a peace invitation was extended by the Onondaga Nation, one of the five nations of the Iroquois Confederacy, to New France, and an expedition of Jesuits, led by Simon Le Moyne, established Sainte Marie de Ganentaa in 1656. The Jesuits were forced to abandon the mission by 1658, as hostilities with the Iroquois resumed. The second article of the charter of the Compagnie des Cent-Associés stated that New France could only be Catholic. This resulted in Huguenots facing legal restrictions to enter the colony when Cardinal Richelieu transferred the control of the colony to Compagnie des Cent-Associés in 1627. Protestantism was then outlawed in France and all its overseas possessions by the Edict of Fontainebleau in 1685. In spite of that, approximately 15,000 Protestants settled in New France by using socioeconomic pretexts while at the same time concealing their religious background. The Huguenots (a name used to designate French-Speaking Protestants) were a mercantile group, originating from the coastal cities of North-Western France, and had a significant impact on the early development of New France, especially in the regions of Quebec and Acadia, where many people still hold Huguenot surnames to this day. Huguenots were famous for their large and interconnected trading and communication network that spanned throughout France, and most of her colonies. This network was also known for trading with the Dutch Republic, and the Kingdom of England; two of France's most important rivals, that also happened to be Protestant nations. Initially, King Henri IV recognised Protestants as a significant minority within France, and allowed them a certain degree of freedom within their religion. After several years of various skirmishes within Metropolitan France, the Huguenots were deemed to not be "faithful servants of the king", and their mercantile powers stripped, their trading network disbanded, and widespread governmental persecutory policies were enacted both within mainland France and Nouvelle France. In 1661, Louis XIV was able to enact self-rule as his regency ended, and he instituted a variety of anti-Protestant conventions throughout the greater French Empire. Under these new rules, Protestant children were forcibly converted to Catholicism, implemented direct governmental jurisdiction over what were formerly Huguenot-controlled trade routes, and labelled the Protestant communities throughout Nouvelle France (specifically Quebec and Acadia) as significant threats to the colonies, as they might sympathise with English Protestants competing in the same areas and trades. Eventually, Protestants were banned from settling in Nouvelle France, and the existing ones were only allowed to "summer" in the colonies, not "winter" there. Health Public health in New France was generally inadequate, despite the presence of a relatively good medical infrastructure. An apothecary, Louis Hébert In 1617 was engaged by Samuel de Champlain to serve the new colony as physician, surgeon and dispenser of medicines and herbs. After 1685 Michel Sarrazin and François Gaultier served as the King's physician of the colony. The colony opened small hospitals known as "Hôtel-Dieu" in Montréal, Quebec City and Trois-Rivières. These institutions were managed by Catholic Church congregations included surgeons, doctors, apothecaries and healers. They provided care to settlers, soldiers, sailors, and occasionally Native populations. The Hôtel-Dieu in Quebec City cared for an average of 589 people per year from 1689, to 1759. The Congregations organized and financed healthcare services. Their care aimed at both spiritual and physical healing. The colony faced high mortality rates due to infectious diseases. Epidemics imported from France were deadly. In 1687, measles and typhoid fever killed about 500 people. In 1702-1703, about 8% of the population died of smallpox. Major epidemics hit in 1715, 1731 and 1785. Medical knowledge was limited, and treatments were often based on old French traditions. The towns were unsanitary, with unpaved streets, free-roaming animals, and lack of proper waste disposal. This led to frequent outbreaks of infectious diseases. Outside the towns the low population density mitigated the spread of diseases and conditions were better than France itself. The "Conseil supérieur" introduced laws to improve urban sanitation, such as requiring latrines and proper waste disposal. The British after 1759 made few changes in public health matters. They did bring in a few British military surgeons. Most of the French medical personnel remained and they followed the old routines, but no longer had replacements from Paris. Judiciary of New France In the early stage of French settlement, legal matters fell within the Governor of New France's purview. Under this arrangement, legal disputes were settled in an incoherent fashion due to the Governor's arbitrariness in issuing verdicts. Since 1640, a Seneschal (sénéchal), a Judge (juge d'épée, which literally means 'sword-bearing judge'), and a jurisdiction in Trois-Rivières were created. However, the Seneschal was under the oversight by the Governor, hence the Governor still had rather extensive control over legal matters in New France. In 1651, the Company of New France made the Great Seneschal (Grand Sénéchal) the chief justice. However, the Island of Montreal had its special Governor at that time, who also administered justice on the Island, and had not handed over justice to the Grand Seneschal until 1652. In practice, though, the Great Seneschal was awarded as an honorary title to the son of Jean de Lauson, then Governor of New France; judicial functions were in fact carried out by the Seneschal's deputies. These deputies included such officials as the civil and criminal lieutenant general (lieutenant général civil et criminel), the special lieutenant (lieutenant particulier, acting as assistant royal judge), and the lieutenant fiscal (lieutenant fiscal, acting as tax magistrate). The Civil and Criminal Lieutenant General sat as judge in trials at first instance, whereas appeals would be adjudicated by the Governor, who held the sovereign right to settle final appeals on behalf of the French king. The Great Seneschal also had a magistrate in Trois-Rivières, as well as a bailiff formed by the Society of Priests of Saint Sulpice on the Island of Montreal. Apart from judicial responsibilities, the Great Seneschal was also in charge of convening local nobility in New France, as well as issuing declarations of war if necessary. However, such alternative role of the Great Seneschal was much weakened soon after by having the rights to declare war and to administer finances stripped off from the office because the French crown feared that colonial officers held too much authority. On 13 October 1663, the royal court replaced the Seneschal Office (sénéchaussée). Canada was divided into three districts: the district of Quebec City, the district of Trois-Rivières, and the district of Montreal. Each district had its own separate jurisdiction with a judge appointed by the Crown, known as the civil and criminal lieutenants general. They were responsible for all legal matters, civil and criminal, in each of the districts. In addition to the royal judges, there were other judicial officers in each district. The clerk of court (registrar) was responsible for transcribing all court proceedings as well as other documents relevant to each of the cases. The king's attorney (procureur du roi) was responsible for inquiring into the facts and preparing the case against the accused. In the districts of Quebec City and Montreal, the royal judges had special lieutenants to substitute them whenever they were absent or sick. Feudal courts heard minor cases. The reform also brought the Sovereign Council of New France (Conseil souverain) into existence, which was later renamed the Superior Council (Conseil supérieur). The Sovereign Council effectively acted as the functional equivalent of a Council of State (Conseil d'État) for New France, having the authority to hand down verdicts on final appeal. Initially, the Council convened once every week, and the quorum of the Sovereign Council was seven for criminal matters, or five for civil cases. The council's practices evolved over time. At the Sovereign Council there was a king's attorney-general (procureur général du roi) in charge of the similar tasks as the district king's attorneys. He was also responsible for supervising the king's attorneys' daily operations as well as execution of royal edicts and regulations passed by the council in their respective districts. In 1664, the Custom of Paris (coutume de Paris) was formally set as the main source of law for civil law in France's overseas empire. All royal judges and king's attorneys in New France had to be thoroughly familiar with this compilation of rules. The Custom governed various civil aspects of the daily life in New France, including property, marriage, inheritance, and so on. The Island of Montreal was a special case because its judiciary had been previously held by the Society of St-Sulpice. In 1663, Governor-General of New France Augustin de Saffray de Mésy originally considered appointing Paul de Chomedey, Sieur de Maisonneuve the Governor of the Island of Montreal and consolidating a royal jurisdiction on the island, but the plan garnered the St-Sulpicians' disapproval, who held the Island as its own fiefdom and effectively acted as the island's governor. In other words, the Sovereign Council had not been able to seize effective control over the legal matters of the Island; instead, the St-Sulpicians administered justice on the island. It was not until 16 September 1666, that the St-Sulpicians finally handed over the justice of the Island of Montreal to the Intendant of New France. In 1693, the French king commanded the replacement of the ecclesiastical courts in Montreal with a royal court composed of one royal judge, with appeals going to the Sovereign Council. The introduction of a royal court on the Montreal Island also resulted in the abolition of the feudal court in the fief of Trois-Rivières (then held by the Jesuits). In the Quebec City district, the lower court (tribunal antérieur) was established in 1664 and had jurisdiction to try cases at first instance, but then it was abolished in 1674. The Sovereign Council appointed trial judges (juges inférieurs) to adjudicate cases at first instance until the Provostry of Quebec (prévôté de Québec) was created in May 1677. The Provostry of Quebec was located in the Hall of Justice (palais de justice) in Quebec City and had only one royal judge, also known as the civil and criminal lieutenant general of Quebec City, who heard both civil and criminal cases, as well as district police. Additionally, a court clerk and a king's attorney were appointed to the court; if either of these two officers could not attend the trials due to illness or other untenable circumstances, the Intendant would appoint a temporary substitute. In the early stages of French colonization, the execution of criminal justice in New France was rather arbitrary. The Governor of New France served as the judge to the colonists as well as soldiers. He would announce his verdict at the presence of the chiefs of the Company of One Hundred Associates and that would be final. After the Sovereign Council was established in Quebec in 1663, the Council carried out criminal justice according to the general ordinances of France. In 1670, the Criminal Ordinance was enacted in New France by order of the French king as a codification of the previous criminal laws passed by the Sovereign Council. The ecclesiastical court (tribunal ecclésiastique, or Officialité) was a special court for hearing first instance trials on both religious and secular affairs involving members of the Church. It first appeared in around 1660 but was not officially recognized by state authorities for it was not administered by a bishop, until 1684. Appeals from this court lay with the Sovereign Council. The court of admiralty was created on 12 January 1717 and was the last judicial body set up in Canada during the French colonial period. The court had a judge (also known as the lieutenant-general of the court) appointed by the French admiralty, a king's attorney, a clerk of court, and one or two bailiffs (huissiers). The admiralty court was located in Quebec City and had jurisdiction over all of New France except Louisiana and Louisbourg. The court heard first instance trials on maritime affairs, including commerce and seamen's conduct. During wartime, it also commanded maritime police. Before 1717, the Quebec Provostry performed the duties of the admiralty court. Unlike Canada, Acadia's judicial system was somewhat under-developed during the New France period. Prior to 1670, Acadia was in a state of being contested between various European colonists. None of the European countries—France, England, the Netherlands—were able to put in place a stable jurisdiction there. In 1670, France regained control of Acadia and appointed Mathieu de Goutin as the Civil and Criminal Lieutenant (lieutenant civil et criminel) of Acadia. Simultaneously, the Governor of Acadia was set up and his job was primarily the defense of Acadia from English attacks. The Civil and Criminal Lieutenant was essentially supervised by the Governor, who held superior judicial authority over the Lieutenant, but for most of the time would let the Lieutenant mediate and decide legal affairs. Due to the situation in Acadia as a small settlement of around 399 settlers in 1670–71, vulnerable to foreign invasion, courts were minimal, consisting of only a Civil and Criminal Lieutenant and a king's attorney. There was not an official court in Acadia, although the king's attorney of Acadia performed very similar duties as his counterpart in New France. Yet since Acadia never actually had a court, there was no clerk of court; instead, trials were recorded by a local notary. It is difficult to trace the judicial history of French Acadia as the relevant archives were destroyed in a fire in 1708. Military conflicts The presence of settlers, of businesses from several European countries harvesting furs, along with the interests of the indigenous people in this new competition for North American resources set the scene for significant military conflicts among all parties in New France beginning in 1642, and ending with the Seven Years' War, 1756–1763. Ville-Marie was a noteworthy site for it was the center of defence against the Iroquois, the point of departure for all western and northern journeys, and the meeting point to which the trading Indians brought their annual furs. This placed Ville-Marie, later known as Montreal, at the forefront against the Iroquois, which resulted in its trade being easily and frequently interrupted. The Iroquois were in alliance with the Dutch and English, which allowed them to interrupt the French fur trade and send the furs down the Hudson River to the Dutch and English traders. This also put the Iroquois at warfare against the Hurons, the Algonquians, and any other tribes that were in alliance with the French. If the Iroquois could destroy New France and its Indian allies, they would be able to trade freely and profitably with the Dutch and English on the Hudson River. The Iroquois formally attacked the settlement at today's Quebec City in its foundation year of 1642, and in almost every subsequent year thereafter. A militant theocracy maintained Montreal. In 1653 and 1654, reinforcements arrived at Montreal, which allowed the Iroquois to be halted.[self-published source] In that year the Iroquois made peace with the French. Adam Dollard des Ormeaux, a colonist and soldier of New France, was a notable figure regarding the Iroquois attacks against Montreal. The Iroquois soon resumed their assaults against Montreal, and the few settlers of Montreal fell almost completely to hostile Iroquois forces. The Iroquois did not use typical raiding tactics of moving swiftly and silently. Instead, they captured individuals and brought them back to their own territory. Women and children were made a part of the village, and men encountered slow torturous deaths. In the 1660s, warfare changed, and France began to counterattack. Professional French soldiers had arrived in the New World for the first time, and Alexandre de Prouville led them to invade Iroquois territory. In the spring of 1660, Adam Dollard des Ormeaux led a small militia consisting of 16 men from Montreal against a much larger Iroquois force at the Battle of Long Sault on the Ottawa River. They succeeded in turning back the Iroquois invasion and are responsible for saving Montreal from destruction. They were able to take Chief Canaqueese as a prisoner, and in September 1660, the French returned and burned Iroquois homes and crops. Later that Winter, many Iroquois died due to starvation, and the Iroquois finally agreed to peace which lasted roughly twenty years. The encounter between Ormeaux and the Iroquois is of significance because it dissuaded the Iroquois from further attacks against Montreal. In 1688, King William's War began and the English and Iroquois launched a major assault on New France, after many years of small skirmishes throughout the English and French territories. New France and the Wabanaki Confederacy were able to thwart New England expansion into Acadia, whose border New France defined as the Kennebec River in southern Maine. King William's War ended in 1697, but a second war (Queen Anne's War) broke out in 1702. Quebec survived the English invasions of both these wars, and during the wars France seized many of the English Hudson's Bay Company fur trading centres on Hudson Bay including York Factory, which the French renamed Fort Bourbon. While Acadia defeated an English invasion attempt during King William's War, the colony was occupied by the British during Queen Anne's War. The final Conquest of Acadia happened in 1710. In 1713, peace came to New France with the Treaty of Utrecht. Although the treaty turned Hudson Bay, Newfoundland and part of Acadia (peninsular Nova Scotia) over to Great Britain, France remained in control of Île Royale (Cape Breton Island) (which also administered Île Saint-Jean (Prince Edward Island)). The northern part of Acadia, what is today New Brunswick and Maine, remained contested territory. Construction of Fortress Louisbourg on Île Royale, a French military stronghold intended to protect the approaches to the St. Lawrence River settlements, began in 1719. In Acadia, however, war continued. Father Rale's War (1722–1725) was a series of battles between New England and the Wabanaki Confederacy, who were allied with New France. New France and the Wabanaki Confederacy defended against the expansion of New England settlements into Acadia, whose border New France defined as the Kennebec River in southern Maine. After the New England Conquest of Acadia in 1710, mainland Nova Scotia was under the control of New England, but both present-day New Brunswick and virtually all of present-day Maine remained contested territory between New England and New France. To secure New France's claim to the region, it established Catholic missions among the three largest indigenous villages in the region: one on the Kennebec River (Norridgewock); one further north on the Penobscot River (Penobscot) and one on the Saint John River (Medoctec). The war began on two fronts: when New England pushed its way through Maine and when New England established itself at Canso, Nova Scotia. As a result of the war, Maine fell to the New Englanders with the defeat of Father Sébastien Rale at Norridgewock and the subsequent retreat of the indigenous peoples from the Kennebec and Penobscot rivers to St. Francis and Becancour, Quebec.[e] Peace lasted in Canada until 1744, when news of the outbreak of the War of the Austrian Succession (King George's War in North America) reached Fort Louisbourg. The French forces went on the attack first in a failed attempt to capture Annapolis Royal, the capital of British Nova Scotia. In 1745, William Shirley, governor of Massachusetts, led a counterattack on Louisbourg. Both France and New France were unable to relieve the siege, and Louisbourg fell to the British. With the famed Duc d'Anville Expedition, France attempted to retake Acadia and the fortress in 1746 but failed. The fortress was returned to France under the Treaty of Aix-la-Chapelle, but the peace treaty, which restored all colonial borders to their pre-war status, did little to end the lingering enmity between France, Britain, and their respective colonies, nor did it resolve any territorial disputes.[citation needed] Within Acadia and Nova Scotia, Father Le Loutre's War (1749–1755) began with the British founding of Halifax. During Father Le Loutre's War, New France established three forts along the border of present-day New Brunswick to protect it from a New England attack from Nova Scotia. The war continued until British victory at Fort Beausejour, which dislodged Father Le Loutre from the region, thereby ending his alliance with the Maliseet, Acadians and Mi'kmaq. Fort Duquesne, located at the confluence of the Allegheny and Monongahela Rivers at the site of present-day Pittsburgh, Pennsylvania, guarded the most important strategic location in the west at the time of the Seven Years' War. It was built to ensure that the Ohio River valley remained under French control. A small colonial force from Virginia began a fort here, but a French force under Claude-Pierre Pécaudy de Contrecœur drove them off in April 1754. New France claimed this as part of their colony, and the French were anxious to keep the British from encroaching on it. The French built Fort Duquesne here to serve as a military stronghold and as a base for developing trade and strengthening military alliances with the indigenous peoples of the area. In 1755, General Edward Braddock led an expedition against Fort Duquesne, and although they were numerically superior to the French militia and their Indian allies, Braddock's army was routed and Braddock was killed. Later that same year at the Battle of Lake George, the British General William Johnson with a force of 1700 American and Iroquois troops defeated a French force of 2800 French and Canadians and 700 Native Americans led by Baron Dieskau (Military commander of New France). The fight for control over Ohio Country led to the French and Indian War, which began as the North American phase of the Seven Years' War (which did not technically begin in Europe until 1756). The war began with the defeat of a Virginia militia contingent led by Colonel George Washington by the French troupes de la marine in the Ohio valley. As a result of that defeat, the British decided to prepare the conquest of Quebec City, the capital of New France. The British defeated France in Acadia in the Battle of Fort Beausejour (1755) and then Île Royale (Cape Breton Island) (which also administered Île Saint-Jean (Prince Edward Island) with the Siege of Louisbourg (1758). Throughout the war, the British deported the Acadians to the Thirteen Colonies and Europe, which the Acadian militias resisted with assistance from Mi'kmaq and Malisteet forces. The Great Upheaval continued from 1755 to 1764. In 1756, a large force of French, Canadians, and their Native American allies led by the Marquis de Montcalm launched an attack against the key British post at Fort Oswego on Lake Ontario from Fort Frontenac and forced the garrison to surrender. The following year Montcalm with a huge force of 7,200 French and Canadian troops and 2,400 Native Americans laid siege to Fort William Henry on the southern shores of Lake George, and after three weeks of fighting the British commander Monroe surrendered. Montcalm gave him honorable terms to return to England and not to fight for 18 months. And yet, when the British force with civilians was three miles from the fort, the Native American allies massacred about 1,100 of the 1,500 strong force. In 1758, the French suffered a defeat when the British captured the fortress city of Louisborg in July, while gaining a victory at Fort Carillon in July. The Battle of Carillon was fought at the fortress of the same name, which is located on a strip of land between Lake Champlain and Lake George, and which was defended by 3,400 French regular troops and marines, with minimal support from militia and indigenous peoples. The battle was the largest seen in North America up to that time, as General James Abercrombie assembled a force of 16,200 British, American, and Iroquois troops. A spirited French defense led the British to withdraw after a fierce battle on the 8th of July, 1758. During the battle, the British suffered 2,200 casualties and lost several artillery pieces, while the French received roughly 104 killed and 273 wounded. While the British Conquest of Acadia happened in 1710, the French continued to remain a significant force in the region with Fort Beausejour and Fortress Louisbourg. The dominant population in the region remained Acadian, that is to say, not British. In 1755, the British were successful in the Battle of Beausejour and immediately after began the expulsion of the Acadians. In the meantime the French continued to explore westwards and expand their trade alliances with indigenous peoples. Fort de la Corne was built in 1753, by Louis de la Corne, Chevalier de la Corne just east of the Saskatchewan River Forks in what is today the Canadian province of Saskatchewan. This was the furthest westward outpost of the French Empire in North America to be established before its fall. Treaties of cession In 1758, British forces again captured Louisbourg, allowing them to blockade the entrance to the St. Lawrence River. This proved decisive in the war. In 1759, the British besieged Quebec by sea, and an army under General James Wolfe defeated the French under General Louis-Joseph de Montcalm at the Battle of the Plains of Abraham in September. The garrison in Quebec surrendered on 18 September, and by the next year New France had been conquered by the British after the attack on Montreal, which had refused to acknowledge the fall of Canada. The last French governor-general of New France, Pierre François de Rigaud, Marquis de Vaudreuil-Cavagnal, surrendered to British Major General Jeffery Amherst on 8 September 1760. France formally ceded Canada to the British in the Treaty of Paris, signed 10 February 1763. Aftermath The expelled Acadians were initially dispersed across much of eastern North America (including the Thirteen Colonies) and some were sent to France. Many eventually settled in Quebec or Louisiana, while others returned to the regions of New Brunswick and Nova Scotia. Chéticamp, Nova Scotia, and the Magdalen Islands have significant communities. In Louisiana their descendants became known as the Cajuns, a corruption of the French Acadiens. By the mid-1700s, the French settlers were well established with a population around 70,000, mainly due to natural increase. The European population had grown slowly under French rule. The British Thirteen Colonies to the south along the Atlantic coast grew in population from natural increase and more new settlers from Europe. By 1760, almost 1.6 million people lived in the British colonies, a ratio of approximately twenty-three to one compared to New France. The population of the New England colonies alone in 1760 was nearly 450,000. French culture and religion remained dominant in most of the former territory of New France until the arrival of British settlers led to the later creation of Upper Canada (today Ontario) and New Brunswick. The Louisiana Territory, under Spanish control since the end of the Seven Years' War, remained off-limits to settlement from the thirteen American colonies. Twelve years after the British defeated the French, the American Revolutionary War broke out in the Thirteen Colonies. Many French Canadians would take part in the war, including Major Clément Gosselin and Admiral Louis-Philippe de Vaudreuil. After the British surrender at Yorktown in 1781, the Treaty of Versailles gave all former British claims in New France below the Great Lakes into the possession of the nascent United States. A Franco-Spanish alliance treaty returned Louisiana to France in 1801, but French leader Napoleon Bonaparte sold it to the United States in the Louisiana Purchase in 1803, ending French colonial efforts in North America. The portions of the former New France that remained under British rule were administered as Upper Canada and Lower Canada, 1791–1841, and then those regions were merged as the Province of Canada during 1841–1867, when the passage of the British North America Act 1867 instituted home rule for most of British North America and established French-speaking Quebec (the former Lower Canada) as one of the original provinces of the Dominion of Canada. The former French colony of Acadia was first designated the Colony of Nova Scotia but shortly thereafter the Colony of New Brunswick, which then included Prince Edward Island, was split off from it. In Canada, the legacy of New France can be seen in the enduring Francophone identity of its descendants, which has led to institutional bilingualism in Canada as a whole. The French overseas collectivity of Saint Pierre and Miquelon (French: Collectivité territoriale de Saint-Pierre-et-Miquelon), consisting of a group of small islands 25 kilometres (16 mi; 13 nmi) off the coast of Newfoundland, were ceded to France by Britain in 1763 to assist with existing French fishing rights: the islands are not remnants of New France.[citation needed] Historiography The Conquest (referring to the fall of New France to the British, and specifically the events of 1759–60) has always been a central and contested theme of Canadian memory. Some Anglophone historians portray the Conquest as a victory for "British military, political and economic superiority" and argue that it ultimately brought benefits to the French settlers. However, Cornelius Jaenen notes that French-Canadian historians remain strongly divided on the subject. One group sees it as a highly negative economic, political and ideological disaster that threatened a way of life with materialism and Protestantism. At the other pole are those historians who see the positive benefit of enabling the preservation of language, and religion and traditional customs under British rule. French-Canadian debates have escalated since the 1960s, as the conquest is seen as a pivotal moment in the history of Québec's nationalism. Francophone historian Jocelyn Létourneau suggested in 2009, that today, "1759 does not belong primarily to a past that we might wish to study and understand, but, rather, to a present and a future that we might wish to shape and control." The enduring contestation of the legacy of the Conquest can be exemplified by an episode in 2009, when an attempt to commemorate the 250th anniversary of the battle of the Plains of Abraham was cancelled. The explanation for the cancellation was that it was over security concerns, but activist Sylvain Rocheleau stated, "[I think] they had to cancel the event because it was insulting a majority of Francophones. They had to cancel it because it was a bad idea.". See also Notes References Further reading External links |
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[SOURCE: https://en.wikipedia.org/wiki/Plagioclase_feldspar] | [TOKENS: 3006] |
Contents Plagioclase Plagioclase (/ˈplædʒ(i)əˌkleɪs, ˈpleɪdʒ-, -ˌkleɪz/ PLAJ-(ee)-ə-klayss, PLAYJ-, -klayz) is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more properly known as the plagioclase feldspar series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel (1796–1872) in 1826. The series ranges from albite to anorthite endmembers (with respective compositions NaAlSi3O8 to CaAl2Si2O8), where sodium and calcium atoms can substitute for each other in the mineral's crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or "record-groove" effect. Plagioclase is a major constituent mineral in Earth's crust and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolution of igneous rocks. Plagioclase is also a major constituent of rock in the highlands of the Moon. Analysis of thermal emission spectra from the surface of Mars suggests that plagioclase is the most abundant mineral in the crust of Mars. Its name comes from Ancient Greek πλάγιος (plágios) 'oblique' and κλάσις (klásis) 'fracture', in reference to its two cleavage angles. Properties Plagioclase is the most common and abundant mineral group in the Earth's crust. Part of the feldspar family of minerals, it is abundant in igneous and metamorphic rock, and it is also common as a detrital mineral in sedimentary rock. It is not a single mineral, but is a solid solution of two end members, albite or sodium feldspar (NaAlSi3O8) and anorthite or calcium feldspar (CaAl2Si2O8). These can be present in plagioclase in any proportion from pure anorthite to pure albite. The composition of plagioclase can thus be written as Na1−xCaxAl1+xSi3−xO8 where x ranges from 0 for pure albite to 1 for pure anorthite. This solid solution series is known as the plagioclase series. The composition of a particular sample of plagioclase is customarily expressed as the mol% of anorthite in the sample. For example, plagioclase that is 40 mol% anorthite would be described as An40 plagioclase. The ability of albite and anorthite to form solid solutions in any proportions at elevated temperature reflects the ease with which calcium and aluminium can substitute for sodium and silicon in the plagioclase crystal structure. Although a calcium ion has a charge of +2, versus +1 for a sodium ion, the two ions have very nearly the same effective radius. The difference in charge is accommodated by the coupled substitution of aluminium (charge +3) for silicon (charge +4), both of which can occupy tetrahedral sites (surrounded by four oxygen ions). This contrasts with potassium, which has the same charge as sodium, but is a significantly larger ion. As a result of the size and charge difference between potassium and calcium, there is a very wide miscibility gap between anorthite and potassium feldspar, (KAlSi3O8), the third common rock-forming feldspar end member. Potassium feldspar does form a solid solution series with albite, due to the identical charges of sodium and potassium ions, which is known as the alkali feldspar series. Thus, almost all feldspar found on Earth is either plagioclase or alkali feldspar, with the two series overlapping for pure albite. When a plagioclase composition is described by its anorthite mol% (such as An40 in the previous example) it is assumed that the remainder is albite, with only a minor component of potassium feldspar. Plagioclase of any composition shares many basic physical characteristics, while other characteristics vary smoothly with composition. The Mohs hardness of all plagioclase species is 6 to 6.5, and cleavage is perfect on and good on , with the cleavage planes meeting at an angle of 93 to 94 degrees. It is from this slightly oblique cleavage angle that plagioclase gets its name, Ancient Greek plágios (πλάγιος 'oblique') + klásis (κλάσις 'fracture'). The name was introduced by August Breithaupt in 1847. There is also a poor cleavage on rarely seen in hand samples. The luster is vitreous to pearly and the diaphaneity is transparent to translucent. The tenacity is brittle, and the fracture is uneven or conchoidal, but the fracture is rarely observed due to the strong tendency of the mineral to cleave instead. At low temperature, the crystal structure belongs to the triclinic system, space group P1 Well-formed crystals are rare and are most commonly sodic in composition. Well-shaped samples are instead typically cleavage fragments. Well-formed crystals are typically bladed or tabular parallel to . Plagioclase is usually white to greyish-white in color, with a slight tendency for more calcium-rich samples to be darker. Impurities can infrequently tint the mineral greenish, yellowish, or flesh-red. Ferric iron (Fe3+) gives a pale yellow color in plagioclase feldspar from Lake County, Oregon. The specific gravity increases smoothly with calcium content, from 2.62 for pure albite to 2.76 for pure anorthite, and this can provide a useful estimate of composition if measured accurately. The index of refraction likewise varies smoothly from 1.53 to 1.58, and, if measured carefully, this also gives a useful composition estimate. Plagioclase almost universally shows a characteristic polysynthetic twinning that produces twinning striations on . These striations allow plagioclase to be distinguished from alkali feldspar. Plagioclase often also displays Carlsbad, Baveno, and Manebach Law twinning. Plagioclase series members The composition of a plagioclase feldspar is typically denoted by its overall fraction of anorthite (%An) or albite (%Ab). There are several named plagioclase feldspars that fall between albite and anorthite in the series. The following table shows their compositions in terms of constituent anorthite and albite percentages. The distinction between these minerals cannot easily be made in the field. The composition can be roughly determined by specific gravity, but accurate measurement requires chemical or optical tests. The composition in a crushed grain mount can be obtained by the Tsuboi method, which yields an accurate measurement of the minimum refractive index that in turn gives an accurate composition. In thin section, the composition can be determined by either the Michel Lévy or Carlsbad-albite methods. The former relies on accurate measure of minimum index of refraction, while the latter relies on measuring the extinction angle under a polarizing microscope. The extinction angle is an optical characteristic and varies with the albite fraction (%Ab). The intermediate members of the plagioclase group are very similar to each other and normally cannot be distinguished except by their optical properties. The specific gravity in each member (albite 2.62) increases 0.02 per 10% increase in anorthite (2.75). Petrogenesis Plagioclase is the primary aluminium-bearing mineral in mafic rocks formed at low pressure. It is normally the first and most abundant feldspar to crystallize from a cooling primitive magma. Anorthite has a much higher melting point than albite, and, as a result, calcium-rich plagioclase is the first to crystallize. The plagioclase becomes more enriched in sodium as the temperature drops, forming Bowen's continuous reaction series. However, the composition with which plagioclase crystallizes also depends on the other components of the melt, so it is not by itself a reliable thermometer. The liquidus of plagioclase (the temperature at which the plagioclase first begins to crystallize) is about 1,215 °C (2,219 °F) for olivine basalt, with a composition of 50.5 wt% silica; 1,255 °C (2,291 °F) in andesite with a silica content of 60.7 wt%; and 1,275 °C (2,327 °F) in dacite with a silica content of 69.9 wt%. These values are for dry magma. The liquidus is greatly lowered by the addition of water, and much more for plagioclase than for mafic minerals. The eutectic (minimum melting mixture) for a mixture of anorthite and diopside shifts from 40 wt% anorthite to 78 wt% anorthite as the water vapor pressure goes from 1 bar to 10 kbar. The presence of water also shifts the composition of the crystallizing plagioclase towards anorthite. The eutectic for this wet mixture drops to about 1,010 °C (1,850 °F). Crystallizing plagioclase is always richer in anorthite than the melt from which it crystallizes. This plagioclase effect causes the residual melt to be enriched in sodium and silicon and depleted in aluminium and calcium. However, the simultaneous crystallization of mafic minerals not containing aluminium can partially offset the depletion in aluminium. In volcanic rock, the crystallized plagioclase incorporates most of the potassium in the melt as a trace element. New plagioclase crystals nucleate only with difficulty, and diffusion is very slow within the solid crystals. As a result, as a magma cools, increasingly sodium-rich plagioclase is usually crystallized onto the rims of existing plagioclase crystals, which retain their more calcium-rich cores. This results in compositional zoning of plagioclase in igneous rocks. In rare cases, plagioclase shows reverse zoning, with a more calcium-rich rim on a more sodium-rich core. Plagioclase also sometimes shows oscillatory zoning, with the zones fluctuating between sodium-rich and calcium-rich compositions, though this is usually superimposed on an overall normal zoning trend. Plagioclase is very important for the classification of crystalline igneous rocks. Generally, the more silica is present in the rock, the fewer the mafic minerals, and the more sodium-rich the plagioclase. Alkali feldspar appears as the silica content becomes high. Under the QAPF classification, plagioclase is one of the three key minerals, along with quartz and alkali feldspar, used to make the initial classification of the rock type. Low-silica igneous rocks are further divided into dioritic rocks having sodium-rich plagioclase (An<50) and gabbroic rocks having calcium-rich plagioclase (An>50). Anorthosite is an intrusive rock composed of at least 90% plagioclase. Albite is an end member of both the alkali and plagioclase series. However, it is included in the alkali feldspar fraction of the rock in the QAPF classification. Plagioclase is also common in metamorphic rock. Plagioclase tends to be albite in low-grade metamorphic rock, while oligoclase to andesine are more common in medium- to high-grade metamorphic rock. Metacarbonate rock sometimes contains fairly pure anorthite. Feldspar makes up between 10 and 20 percent of the framework grains in typical sandstones. Alkali feldspar is usually more abundant than plagioclase in sandstone because Alkali feldspars are more resistant to chemical weathering and more stable, but sandstone derived from volcanic rock contains more plagioclase. Plagioclase weathers relatively rapidly to clay minerals such as smectite. The Mohorovičić discontinuity, which defines the boundary between the Earth's crust and the upper mantle, is thought to be the depth where feldspar disappears from the rock. While plagioclase is the most important aluminium-bearing mineral in the crust, it breaks down at the high pressure of the upper mantle, with the aluminium tending to be incorporated into clinopyroxene as Tschermak's molecule (CaAl2SiO6) or in jadeite NaAlSi2O6. At still higher pressure, the aluminium is incorporated into garnet. At very high temperatures, plagioclase forms a solid solution with potassium feldspar, but this becomes highly unstable on cooling. The plagioclase separates from the potassium feldspar, a process called exsolution. The resulting rock, in which fine streaks of plagioclase (lamellae) are present in potassium feldspar, is called perthite. The solid solution between anorthite and albite remains stable to lower temperatures, but ultimately becomes unstable as the rock approaches ambient surface temperatures. The resulting exsolution results in very fine lamellar and other intergrowths, normally detected only by sophisticated means. However, exsolution in the andesine to labradorite compositional range sometimes produces lamellae with thicknesses comparable to the wavelength of visible light. This acts like a diffraction grating, causing the labradorite to show the beautiful play of colors known as chatoyance. Uses In addition to its importance to geologists in classifying igneous rocks, plagioclase finds practical use as construction aggregate, as dimension stone, and in powdered form as a filler in paint, plastics, and rubber. Sodium-rich plagioclase finds use in the manufacture of glass and ceramics. Anorthosite could someday be important as a source of aluminium. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Internet#cite_note-66] | [TOKENS: 9291] |
Contents Internet The Internet (or internet)[a] is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP)[b] to communicate between networks and devices. It is a network of networks that comprises private, public, academic, business, and government networks of local to global scope, linked by electronic, wireless, and optical networking technologies. The Internet carries a vast range of information services and resources, such as the interlinked hypertext documents and applications of the World Wide Web (WWW), electronic mail, discussion groups, internet telephony, streaming media and file sharing. Most traditional communication media, including telephone, radio, television, paper mail, newspapers, and print publishing, have been transformed by the Internet, giving rise to new media such as email, online music, digital newspapers, news aggregators, and audio and video streaming websites. The Internet has enabled and accelerated new forms of personal interaction through instant messaging, Internet forums, and social networking services. Online shopping has also grown to occupy a significant market across industries, enabling firms to extend brick and mortar presences to serve larger markets. Business-to-business and financial services on the Internet affect supply chains across entire industries. The origins of the Internet date back to research that enabled the time-sharing of computer resources, the development of packet switching, and the design of computer networks for data communication. The set of communication protocols to enable internetworking on the Internet arose from research and development commissioned in the 1970s by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense in collaboration with universities and researchers across the United States and in the United Kingdom and France. The Internet has no single centralized governance in either technological implementation or policies for access and usage. Each constituent network sets its own policies. The overarching definitions of the two principal name spaces on the Internet, the Internet Protocol address (IP address) space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols is an activity of the non-profit Internet Engineering Task Force (IETF). Terminology The word internetted was used as early as 1849, meaning interconnected or interwoven. The word Internet was used in 1945 by the United States War Department in a radio operator's manual, and in 1974 as the shorthand form of Internetwork. Today, the term Internet most commonly refers to the global system of interconnected computer networks, though it may also refer to any group of smaller networks. The word Internet may be capitalized as a proper noun, although this is becoming less common. This reflects the tendency in English to capitalize new terms and move them to lowercase as they become familiar. The word is sometimes still capitalized to distinguish the global internet from smaller networks, though many publications, including the AP Stylebook since 2016, recommend the lowercase form in every case. In 2016, the Oxford English Dictionary found that, based on a study of around 2.5 billion printed and online sources, "Internet" was capitalized in 54% of cases. The terms Internet and World Wide Web are often used interchangeably; it is common to speak of "going on the Internet" when using a web browser to view web pages. However, the World Wide Web, or the Web, is only one of a large number of Internet services. It is the global collection of web pages, documents and other web resources linked by hyperlinks and URLs. History In the 1960s, computer scientists began developing systems for time-sharing of computer resources. J. C. R. Licklider proposed the idea of a universal network while working at Bolt Beranek & Newman and, later, leading the Information Processing Techniques Office at the Advanced Research Projects Agency (ARPA) of the United States Department of Defense. Research into packet switching,[c] one of the fundamental Internet technologies, started in the work of Paul Baran at RAND in the early 1960s and, independently, Donald Davies at the United Kingdom's National Physical Laboratory in 1965. After the Symposium on Operating Systems Principles in 1967, packet switching from the proposed NPL network was incorporated into the design of the ARPANET, an experimental resource sharing network proposed by ARPA. ARPANET development began with two network nodes which were interconnected between the University of California, Los Angeles and the Stanford Research Institute on 29 October 1969. The third site was at the University of California, Santa Barbara, followed by the University of Utah. By the end of 1971, 15 sites were connected to the young ARPANET. Thereafter, the ARPANET gradually developed into a decentralized communications network, connecting remote centers and military bases in the United States. Other user networks and research networks, such as the Merit Network and CYCLADES, were developed in the late 1960s and early 1970s. Early international collaborations for the ARPANET were rare. Connections were made in 1973 to Norway (NORSAR and, later, NDRE) and to Peter Kirstein's research group at University College London, which provided a gateway to British academic networks, the first internetwork for resource sharing. ARPA projects, the International Network Working Group and commercial initiatives led to the development of various protocols and standards by which multiple separate networks could become a single network, or a network of networks. In 1974, Vint Cerf at Stanford University and Bob Kahn at DARPA published a proposal for "A Protocol for Packet Network Intercommunication". Cerf and his graduate students used the term internet as a shorthand for internetwork in RFC 675. The Internet Experiment Notes and later RFCs repeated this use. The work of Louis Pouzin and Robert Metcalfe had important influences on the resulting TCP/IP design. National PTTs and commercial providers developed the X.25 standard and deployed it on public data networks. The ARPANET initially served as a backbone for the interconnection of regional academic and military networks in the United States to enable resource sharing. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded the Computer Science Network (CSNET). In 1982, the Internet Protocol Suite (TCP/IP) was standardized, which facilitated worldwide proliferation of interconnected networks. TCP/IP network access expanded again in 1986 when the National Science Foundation Network (NSFNet) provided access to supercomputer sites in the United States for researchers, first at speeds of 56 kbit/s and later at 1.5 Mbit/s and 45 Mbit/s. The NSFNet expanded into academic and research organizations in Europe, Australia, New Zealand and Japan in 1988–89. Although other network protocols such as UUCP and PTT public data networks had global reach well before this time, this marked the beginning of the Internet as an intercontinental network. Commercial Internet service providers emerged in 1989 in the United States and Australia. The ARPANET was decommissioned in 1990. The linking of commercial networks and enterprises by the early 1990s, as well as the advent of the World Wide Web, marked the beginning of the transition to the modern Internet. Steady advances in semiconductor technology and optical networking created new economic opportunities for commercial involvement in the expansion of the network in its core and for delivering services to the public. In mid-1989, MCI Mail and Compuserve established connections to the Internet, delivering email and public access products to the half million users of the Internet. Just months later, on 1 January 1990, PSInet launched an alternate Internet backbone for commercial use; one of the networks that added to the core of the commercial Internet of later years. In March 1990, the first high-speed T1 (1.5 Mbit/s) link between the NSFNET and Europe was installed between Cornell University and CERN, allowing much more robust communications than were capable with satellites. Later in 1990, Tim Berners-Lee began writing WorldWideWeb, the first web browser, after two years of lobbying CERN management. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the HyperText Transfer Protocol (HTTP) 0.9, the HyperText Markup Language (HTML), the first Web browser (which was also an HTML editor and could access Usenet newsgroups and FTP files), the first HTTP server software (later known as CERN httpd), the first web server, and the first Web pages that described the project itself. In 1991 the Commercial Internet eXchange was founded, allowing PSInet to communicate with the other commercial networks CERFnet and Alternet. Stanford Federal Credit Union was the first financial institution to offer online Internet banking services to all of its members in October 1994. In 1996, OP Financial Group, also a cooperative bank, became the second online bank in the world and the first in Europe. By 1995, the Internet was fully commercialized in the U.S. when the NSFNet was decommissioned, removing the last restrictions on use of the Internet to carry commercial traffic. As technology advanced and commercial opportunities fueled reciprocal growth, the volume of Internet traffic started experiencing similar characteristics as that of the scaling of MOS transistors, exemplified by Moore's law, doubling every 18 months. This growth, formalized as Edholm's law, was catalyzed by advances in MOS technology, laser light wave systems, and noise performance. Since 1995, the Internet has tremendously impacted culture and commerce, including the rise of near-instant communication by email, instant messaging, telephony (Voice over Internet Protocol or VoIP), two-way interactive video calls, and the World Wide Web. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1 Gbit/s, 10 Gbit/s, or more. The Internet continues to grow, driven by ever-greater amounts of online information and knowledge, commerce, entertainment and social networking services. During the late 1990s, it was estimated that traffic on the public Internet grew by 100 percent per year, while the mean annual growth in the number of Internet users was thought to be between 20% and 50%. This growth is often attributed to the lack of central administration, which allows organic growth of the network, as well as the non-proprietary nature of the Internet protocols, which encourages vendor interoperability and prevents any one company from exerting too much control over the network. In November 2006, the Internet was included on USA Today's list of the New Seven Wonders. As of 31 March 2011[update], the estimated total number of Internet users was 2.095 billion (30% of world population). It is estimated that in 1993 the Internet carried only 1% of the information flowing through two-way telecommunication. By 2000 this figure had grown to 51%, and by 2007 more than 97% of all telecommunicated information was carried over the Internet. Modern smartphones can access the Internet through cellular carrier networks, and internet usage by mobile and tablet devices exceeded desktop worldwide for the first time in October 2016. As of 2018[update], 80% of the world's population were covered by a 4G network. The International Telecommunication Union (ITU) estimated that, by the end of 2017, 48% of individual users regularly connect to the Internet, up from 34% in 2012. Mobile Internet connectivity has played an important role in expanding access in recent years, especially in Asia and the Pacific and in Africa. The number of unique mobile cellular subscriptions increased from 3.9 billion in 2012 to 4.8 billion in 2016, two-thirds of the world's population, with more than half of subscriptions located in Asia and the Pacific. The limits that users face on accessing information via mobile applications coincide with a broader process of fragmentation of the Internet. Fragmentation restricts access to media content and tends to affect the poorest users the most. One solution, zero-rating, is the practice of Internet service providers allowing users free connectivity to access specific content or applications without cost. Social impact The Internet has enabled new forms of social interaction, activities, and social associations, giving rise to the scholarly study of the sociology of the Internet. Between 2000 and 2009, the number of Internet users globally rose from 390 million to 1.9 billion. By 2010, 22% of the world's population had access to computers with 1 billion Google searches every day, 300 million Internet users reading blogs, and 2 billion videos viewed daily on YouTube. In 2014 the world's Internet users surpassed 3 billion or 44 percent of world population, but two-thirds came from the richest countries, with 78 percent of Europeans using the Internet, followed by 57 percent of the Americas. However, by 2018, Asia alone accounted for 51% of all Internet users, with 2.2 billion out of the 4.3 billion Internet users in the world. China's Internet users surpassed a major milestone in 2018, when the country's Internet regulatory authority, China Internet Network Information Centre, announced that China had 802 million users. China was followed by India, with some 700 million users, with the United States third with 275 million users. However, in terms of penetration, in 2022, China had a 70% penetration rate compared to India's 60% and the United States's 90%. In 2022, 54% of the world's Internet users were based in Asia, 14% in Europe, 7% in North America, 10% in Latin America and the Caribbean, 11% in Africa, 4% in the Middle East and 1% in Oceania. In 2019, Kuwait, Qatar, the Falkland Islands, Bermuda and Iceland had the highest Internet penetration by the number of users, with 93% or more of the population with access. As of 2022, it was estimated that 5.4 billion people use the Internet, more than two-thirds of the world's population. Early computer systems were limited to the characters in the American Standard Code for Information Interchange (ASCII), a subset of the Latin alphabet. After English (27%), the most requested languages on the World Wide Web are Chinese (25%), Spanish (8%), Japanese (5%), Portuguese and German (4% each), Arabic, French and Russian (3% each), and Korean (2%). Modern character encoding standards, such as Unicode, allow for development and communication in the world's widely used languages. However, some glitches such as mojibake (incorrect display of some languages' characters) still remain. Several neologisms exist that refer to Internet users: Netizen (as in "citizen of the net") refers to those actively involved in improving online communities, the Internet in general or surrounding political affairs and rights such as free speech, Internaut refers to operators or technically highly capable users of the Internet, digital citizen refers to a person using the Internet in order to engage in society, politics, and government participation. The Internet allows greater flexibility in working hours and location, especially with the spread of unmetered high-speed connections. The Internet can be accessed almost anywhere by numerous means, including through mobile Internet devices. Mobile phones, datacards, handheld game consoles and cellular routers allow users to connect to the Internet wirelessly.[citation needed] Educational material at all levels from pre-school (e.g. CBeebies) to post-doctoral (e.g. scholarly literature through Google Scholar) is available on websites. The internet has facilitated the development of virtual universities and distance education, enabling both formal and informal education. The Internet allows researchers to conduct research remotely via virtual laboratories, with profound changes in reach and generalizability of findings as well as in communication between scientists and in the publication of results. By the late 2010s the Internet had been described as "the main source of scientific information "for the majority of the global North population".: 111 Wikis have also been used in the academic community for sharing and dissemination of information across institutional and international boundaries. In those settings, they have been found useful for collaboration on grant writing, strategic planning, departmental documentation, and committee work. The United States Patent and Trademark Office uses a wiki to allow the public to collaborate on finding prior art relevant to examination of pending patent applications. Queens, New York has used a wiki to allow citizens to collaborate on the design and planning of a local park. The English Wikipedia has the largest user base among wikis on the World Wide Web and ranks in the top 10 among all sites in terms of traffic. The Internet has been a major outlet for leisure activity since its inception, with entertaining social experiments such as MUDs and MOOs being conducted on university servers, and humor-related Usenet groups receiving much traffic. Many Internet forums have sections devoted to games and funny videos. Another area of leisure activity on the Internet is multiplayer gaming. This form of recreation creates communities, where people of all ages and origins enjoy the fast-paced world of multiplayer games. These range from MMORPG to first-person shooters, from role-playing video games to online gambling. While online gaming has been around since the 1970s, modern modes of online gaming began with subscription services such as GameSpy and MPlayer. Streaming media is the real-time delivery of digital media for immediate consumption or enjoyment by end users. Streaming companies (such as Netflix, Disney+, Amazon's Prime Video, Mubi, Hulu, and Apple TV+) now dominate the entertainment industry, eclipsing traditional broadcasters. Audio streamers such as Spotify and Apple Music also have significant market share in the audio entertainment market. Video sharing websites are also a major factor in the entertainment ecosystem. YouTube was founded on 15 February 2005 and is now the leading website for free streaming video with more than two billion users. It uses a web player to stream and show video files. YouTube users watch hundreds of millions, and upload hundreds of thousands, of videos daily. Other video sharing websites include Vimeo, Instagram and TikTok.[citation needed] Although many governments have attempted to restrict both Internet pornography and online gambling, this has generally failed to stop their widespread popularity. A number of advertising-funded ostensible video sharing websites known as "tube sites" have been created to host shared pornographic video content. Due to laws requiring the documentation of the origin of pornography, these websites now largely operate in conjunction with pornographic movie studios and their own independent creator networks, acting as de-facto video streaming services. Major players in this field include the market leader Aylo, the operator of PornHub and numerous other branded sites, as well as other independent operators such as xHamster and Xvideos. As of 2023[update], Internet traffic to pornographic video sites rivalled that of mainstream video streaming and sharing services. Remote work is facilitated by tools such as groupware, virtual private networks, conference calling, videotelephony, and VoIP so that work may be performed from any location, such as the worker's home.[citation needed] The spread of low-cost Internet access in developing countries has opened up new possibilities for peer-to-peer charities, which allow individuals to contribute small amounts to charitable projects for other individuals. Websites, such as DonorsChoose and GlobalGiving, allow small-scale donors to direct funds to individual projects of their choice. A popular twist on Internet-based philanthropy is the use of peer-to-peer lending for charitable purposes. Kiva pioneered this concept in 2005, offering the first web-based service to publish individual loan profiles for funding. The low cost and nearly instantaneous sharing of ideas, knowledge, and skills have made collaborative work dramatically easier, with the help of collaborative software, which allow groups to easily form, cheaply communicate, and share ideas. An example of collaborative software is the free software movement, which has produced, among other things, Linux, Mozilla Firefox, and OpenOffice.org (later forked into LibreOffice).[citation needed] Content management systems allow collaborating teams to work on shared sets of documents simultaneously without accidentally destroying each other's work.[citation needed] The internet also allows for cloud computing, virtual private networks, remote desktops, and remote work.[citation needed] The online disinhibition effect describes the tendency of many individuals to behave more stridently or offensively online than they would in person. A significant number of feminist women have been the target of various forms of harassment, including insults and hate speech, to, in extreme cases, rape and death threats, in response to posts they have made on social media. Social media companies have been criticized in the past for not doing enough to aid victims of online abuse. Children also face dangers online such as cyberbullying and approaches by sexual predators, who sometimes pose as children themselves. Due to naivety, they may also post personal information about themselves online, which could put them or their families at risk unless warned not to do so. Many parents choose to enable Internet filtering or supervise their children's online activities in an attempt to protect their children from pornography or violent content on the Internet. The most popular social networking services commonly forbid users under the age of 13. However, these policies can be circumvented by registering an account with a false birth date, and a significant number of children aged under 13 join such sites.[citation needed] Social networking services for younger children, which claim to provide better levels of protection for children, also exist. Internet usage has been correlated to users' loneliness. Lonely people tend to use the Internet as an outlet for their feelings and to share their stories with others, such as in the "I am lonely will anyone speak to me" thread.[citation needed] Cyberslacking can become a drain on corporate resources; employees spend a significant amount of time surfing the Web while at work. Internet addiction disorder is excessive computer use that interferes with daily life. Nicholas G. Carr believes that Internet use has other effects on individuals, for instance improving skills of scan-reading and interfering with the deep thinking that leads to true creativity. Electronic business encompasses business processes spanning the entire value chain: purchasing, supply chain management, marketing, sales, customer service, and business relationship. E-commerce seeks to add revenue streams using the Internet to build and enhance relationships with clients and partners. According to International Data Corporation, the size of worldwide e-commerce, when global business-to-business and -consumer transactions are combined, equate to $16 trillion in 2013. A report by Oxford Economics added those two together to estimate the total size of the digital economy at $20.4 trillion, equivalent to roughly 13.8% of global sales. While much has been written of the economic advantages of Internet-enabled commerce, there is also evidence that some aspects of the Internet such as maps and location-aware services may serve to reinforce economic inequality and the digital divide. Electronic commerce may be responsible for consolidation and the decline of mom-and-pop, brick and mortar businesses resulting in increases in income inequality. A 2013 Institute for Local Self-Reliance report states that brick-and-mortar retailers employ 47 people for every $10 million in sales, while Amazon employs only 14. Similarly, the 700-employee room rental start-up Airbnb was valued at $10 billion in 2014, about half as much as Hilton Worldwide, which employs 152,000 people. At that time, Uber employed 1,000 full-time employees and was valued at $18.2 billion, about the same valuation as Avis Rent a Car and The Hertz Corporation combined, which together employed almost 60,000 people. Advertising on popular web pages can be lucrative, and e-commerce. Online advertising is a form of marketing and advertising which uses the Internet to deliver promotional marketing messages to consumers. It includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising. In 2011, Internet advertising revenues in the United States surpassed those of cable television and nearly exceeded those of broadcast television.: 19 Many common online advertising practices are controversial and increasingly subject to regulation. The Internet has achieved new relevance as a political tool. The presidential campaign of Howard Dean in 2004 in the United States was notable for its success in soliciting donation via the Internet. Many political groups use the Internet to achieve a new method of organizing for carrying out their mission, having given rise to Internet activism. Social media websites, such as Facebook and Twitter, helped people organize the Arab Spring, by helping activists organize protests, communicate grievances, and disseminate information. Many have understood the Internet as an extension of the Habermasian notion of the public sphere, observing how network communication technologies provide something like a global civic forum. However, incidents of politically motivated Internet censorship have now been recorded in many countries, including western democracies. E-government is the use of technological communications devices, such as the Internet, to provide public services to citizens and other persons in a country or region. E-government offers opportunities for more direct and convenient citizen access to government and for government provision of services directly to citizens. Cybersectarianism is a new organizational form that involves: highly dispersed small groups of practitioners that may remain largely anonymous within the larger social context and operate in relative secrecy, while still linked remotely to a larger network of believers who share a set of practices and texts, and often a common devotion to a particular leader. Overseas supporters provide funding and support; domestic practitioners distribute tracts, participate in acts of resistance, and share information on the internal situation with outsiders. Collectively, members and practitioners of such sects construct viable virtual communities of faith, exchanging personal testimonies and engaging in the collective study via email, online chat rooms, and web-based message boards. In particular, the British government has raised concerns about the prospect of young British Muslims being indoctrinated into Islamic extremism by material on the Internet, being persuaded to join terrorist groups such as the so-called "Islamic State", and then potentially committing acts of terrorism on returning to Britain after fighting in Syria or Iraq.[citation needed] Applications and services The Internet carries many applications and services, most prominently the World Wide Web, including social media, electronic mail, mobile applications, multiplayer online games, Internet telephony, file sharing, and streaming media services. The World Wide Web is a global collection of documents, images, multimedia, applications, and other resources, logically interrelated by hyperlinks and referenced with Uniform Resource Identifiers (URIs), which provide a global system of named references. URIs symbolically identify services, web servers, databases, and the documents and resources that they can provide. HyperText Transfer Protocol (HTTP) is the main access protocol of the World Wide Web. Web services also use HTTP for communication between software systems for information transfer, sharing and exchanging business data and logistics and is one of many languages or protocols that can be used for communication on the Internet. World Wide Web browser software, such as Microsoft Edge, Mozilla Firefox, Opera, Apple's Safari, and Google Chrome, enable users to navigate from one web page to another via the hyperlinks embedded in the documents. These documents may also contain computer data, including graphics, sounds, text, video, multimedia and interactive content. Client-side scripts can include animations, games, office applications and scientific demonstrations. Email is an important communications service available via the Internet. The concept of sending electronic text messages between parties, analogous to mailing letters or memos, predates the creation of the Internet. Internet telephony is a common communications service realized with the Internet. The name of the principal internetworking protocol, the Internet Protocol, lends its name to voice over Internet Protocol (VoIP).[citation needed] VoIP systems now dominate many markets, being as easy and convenient as a traditional telephone, while having substantial cost savings, especially over long distances. File sharing is the practice of transferring large amounts of data in the form of computer files across the Internet, for example via file servers. The load of bulk downloads to many users can be eased by the use of "mirror" servers or peer-to-peer networks. Access to the file may be controlled by user authentication, the transit of the file over the Internet may be obscured by encryption, and money may change hands for access to the file. The price can be paid by the remote charging of funds from, for example, a credit card whose details are also passed—usually fully encrypted—across the Internet. The origin and authenticity of the file received may be checked by a digital signature. Governance The Internet is a global network that comprises many voluntarily interconnected autonomous networks. It operates without a central governing body. The technical underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. While the hardware components in the Internet infrastructure can often be used to support other software systems, it is the design and the standardization process of the software that characterizes the Internet and provides the foundation for its scalability and success. The responsibility for the architectural design of the Internet software systems has been assumed by the IETF. The IETF conducts standard-setting work groups, open to any individual, about the various aspects of Internet architecture. The resulting contributions and standards are published as Request for Comments (RFC) documents on the IETF web site. The principal methods of networking that enable the Internet are contained in specially designated RFCs that constitute the Internet Standards. Other less rigorous documents are simply informative, experimental, or historical, or document the best current practices when implementing Internet technologies. To maintain interoperability, the principal name spaces of the Internet are administered by the Internet Corporation for Assigned Names and Numbers (ICANN). ICANN is governed by an international board of directors drawn from across the Internet technical, business, academic, and other non-commercial communities. The organization coordinates the assignment of unique identifiers for use on the Internet, including domain names, IP addresses, application port numbers in the transport protocols, and many other parameters. Globally unified name spaces are essential for maintaining the global reach of the Internet. This role of ICANN distinguishes it as perhaps the only central coordinating body for the global Internet. The National Telecommunications and Information Administration, an agency of the United States Department of Commerce, had final approval over changes to the DNS root zone until the IANA stewardship transition on 1 October 2016. Regional Internet registries (RIRs) were established for five regions of the world to assign IP address blocks and other Internet parameters to local registries, such as Internet service providers, from a designated pool of addresses set aside for each region:[citation needed] The Internet Society (ISOC) was founded in 1992 with a mission to "assure the open development, evolution and use of the Internet for the benefit of all people throughout the world". Its members include individuals as well as corporations, organizations, governments, and universities. Among other activities ISOC provides an administrative home for a number of less formally organized groups that are involved in developing and managing the Internet, including: the Internet Engineering Task Force (IETF), Internet Architecture Board (IAB), Internet Engineering Steering Group (IESG), Internet Research Task Force (IRTF), and Internet Research Steering Group (IRSG). On 16 November 2005, the United Nations-sponsored World Summit on the Information Society in Tunis established the Internet Governance Forum (IGF) to discuss Internet-related issues.[citation needed] Infrastructure The communications infrastructure of the Internet consists of its hardware components and a system of software layers that control various aspects of the architecture. As with any computer network, the Internet physically consists of routers, media (such as cabling and radio links), repeaters, and modems. However, as an example of internetworking, many of the network nodes are not necessarily Internet equipment per se. Internet packets are carried by other full-fledged networking protocols, with the Internet acting as a homogeneous networking standard, running across heterogeneous hardware, with the packets guided to their destinations by IP routers.[citation needed] Internet service providers (ISPs) establish worldwide connectivity between individual networks at various levels of scope. At the top of the routing hierarchy are the tier 1 networks, large telecommunication companies that exchange traffic directly with each other via very high speed fiber-optic cables and governed by peering agreements. Tier 2 and lower-level networks buy Internet transit from other providers to reach at least some parties on the global Internet, though they may also engage in peering. End-users who only access the Internet when needed to perform a function or obtain information, represent the bottom of the routing hierarchy.[citation needed] An ISP may use a single upstream provider for connectivity, or implement multihoming to achieve redundancy and load balancing. Internet exchange points are major traffic exchanges with physical connections to multiple ISPs. Large organizations, such as academic institutions, large enterprises, and governments, may perform the same function as ISPs, engaging in peering and purchasing transit on behalf of their internal networks. Research networks tend to interconnect with large subnetworks such as GEANT, GLORIAD, Internet2, and the UK's national research and education network, JANET.[citation needed] Common methods of Internet access by users include broadband over coaxial cable, fiber optics or copper wires, Wi-Fi, satellite, and cellular telephone technology.[citation needed] Grassroots efforts have led to wireless community networks. Commercial Wi-Fi services that cover large areas are available in many cities, such as New York, London, Vienna, Toronto, San Francisco, Philadelphia, Chicago and Pittsburgh. Most servers that provide internet services are today hosted in data centers, and content is often accessed through high-performance content delivery networks. Colocation centers often host private peering connections between their customers, internet transit providers, cloud providers, meet-me rooms for connecting customers together, Internet exchange points, and landing points and terminal equipment for fiber optic submarine communication cables, connecting the internet. Internet Protocol Suite The Internet standards describe a framework known as the Internet protocol suite (also called TCP/IP, based on the first two components.) This is a suite of protocols that are ordered into a set of four conceptional layers by the scope of their operation, originally documented in RFC 1122 and RFC 1123:[citation needed] The most prominent component of the Internet model is the Internet Protocol. IP enables internetworking, essentially establishing the Internet itself. Two versions of the Internet Protocol exist, IPv4 and IPv6.[citation needed] Aside from the complex array of physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts (e.g., peering agreements), and by technical specifications or protocols that describe the exchange of data over the network.[citation needed] For locating individual computers on the network, the Internet provides IP addresses. IP addresses are used by the Internet infrastructure to direct internet packets to their destinations. They consist of fixed-length numbers, which are found within the packet. IP addresses are generally assigned to equipment either automatically via Dynamic Host Configuration Protocol, or are configured.[citation needed] Domain Name Systems convert user-inputted domain names (e.g. "en.wikipedia.org") into IP addresses.[citation needed] Internet Protocol version 4 (IPv4) defines an IP address as a 32-bit number. IPv4 is the initial version used on the first generation of the Internet and is still in dominant use. It was designed in 1981 to address up to ≈4.3 billion (109) hosts. However, the explosive growth of the Internet has led to IPv4 address exhaustion, which entered its final stage in 2011, when the global IPv4 address allocation pool was exhausted. Because of the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP IPv6, was developed in the mid-1990s, which provides vastly larger addressing capabilities and more efficient routing of Internet traffic. IPv6 uses 128 bits for the IP address and was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s and is currently in growing deployment around the world, since Internet address registries began to urge all resource managers to plan rapid adoption and conversion. By design, IPv6 is not directly interoperable with IPv4. Instead, it establishes a parallel version of the Internet not directly accessible with IPv4 software. Thus, translation facilities exist for internetworking, and some nodes have duplicate networking software for both networks. Essentially all modern computer operating systems support both versions of the Internet Protocol.[citation needed] Network infrastructure, however, has been lagging in this development.[citation needed] A subnet or subnetwork is a logical subdivision of an IP network.: 1, 16 Computers that belong to a subnet are addressed with an identical most-significant bit-group in their IP addresses. This results in the logical division of an IP address into two fields, the network number or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.[citation needed] The routing prefix may be expressed in Classless Inter-Domain Routing (CIDR) notation written as the first address of a network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 198.51.100.0/24 is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. The IPv6 address specification 2001:db8::/32 is a large address block with 296 addresses, having a 32-bit routing prefix.[citation needed] For IPv4, a network may also be characterized by its subnet mask or netmask, which is the bitmask that when applied by a bitwise AND operation to any IP address in the network, yields the routing prefix. Subnet masks are also expressed in dot-decimal notation like an address. For example, 255.255.255.0 is the subnet mask for the prefix 198.51.100.0/24.[citation needed] Computers and routers use routing tables in their operating system to forward IP packets to reach a node on a different subnetwork. Routing tables are maintained by manual configuration or automatically by routing protocols. End-nodes typically use a default route that points toward an ISP providing transit, while ISP routers use the Border Gateway Protocol to establish the most efficient routing across the complex connections of the global Internet.[citation needed] The default gateway is the node that serves as the forwarding host (router) to other networks when no other route specification matches the destination IP address of a packet. Security Internet resources, hardware, and software components are the target of criminal or malicious attempts to gain unauthorized control to cause interruptions, commit fraud, engage in blackmail or access private information. Malware is malicious software used and distributed via the Internet. It includes computer viruses which are copied with the help of humans, computer worms which copy themselves automatically, software for denial of service attacks, ransomware, botnets, and spyware that reports on the activity and typing of users.[citation needed] Usually, these activities constitute cybercrime. Defense theorists have also speculated about the possibilities of hackers using cyber warfare using similar methods on a large scale. Malware poses serious problems to individuals and businesses on the Internet. According to Symantec's 2018 Internet Security Threat Report (ISTR), malware variants number has increased to 669,947,865 in 2017, which is twice as many malware variants as in 2016. Cybercrime, which includes malware attacks as well as other crimes committed by computer, was predicted to cost the world economy US$6 trillion in 2021, and is increasing at a rate of 15% per year. Since 2021, malware has been designed to target computer systems that run critical infrastructure such as the electricity distribution network. Malware can be designed to evade antivirus software detection algorithms. The vast majority of computer surveillance involves the monitoring of data and traffic on the Internet. In the United States for example, under the Communications Assistance For Law Enforcement Act, all phone calls and broadband Internet traffic (emails, web traffic, instant messaging, etc.) are required to be available for unimpeded real-time monitoring by Federal law enforcement agencies. Under the Act, all U.S. telecommunications providers are required to install packet sniffing technology to allow Federal law enforcement and intelligence agencies to intercept all of their customers' broadband Internet and VoIP traffic.[d] The large amount of data gathered from packet capture requires surveillance software that filters and reports relevant information, such as the use of certain words or phrases, the access to certain types of web sites, or communicating via email or chat with certain parties. Agencies, such as the Information Awareness Office, NSA, GCHQ and the FBI, spend billions of dollars per year to develop, purchase, implement, and operate systems for interception and analysis of data. Similar systems are operated by Iranian secret police to identify and suppress dissidents. The required hardware and software were allegedly installed by German Siemens AG and Finnish Nokia. Some governments, such as those of Myanmar, Iran, North Korea, Mainland China, Saudi Arabia and the United Arab Emirates, restrict access to content on the Internet within their territories, especially to political and religious content, with domain name and keyword filters. In Norway, Denmark, Finland, and Sweden, major Internet service providers have voluntarily agreed to restrict access to sites listed by authorities. While this list of forbidden resources is supposed to contain only known child pornography sites, the content of the list is secret. Many countries, including the United States, have enacted laws against the possession or distribution of certain material, such as child pornography, via the Internet but do not mandate filter software. Many free or commercially available software programs, called content-control software are available to users to block offensive specific on individual computers or networks in order to limit access by children to pornographic material or depiction of violence.[citation needed] Performance As the Internet is a heterogeneous network, its physical characteristics, including, for example the data transfer rates of connections, vary widely. It exhibits emergent phenomena that depend on its large-scale organization. PB per monthYear020,00040,00060,00080,000100,000120,000140,000199019952000200520102015Petabytes per monthGlobal Internet Traffic Volume The volume of Internet traffic is difficult to measure because no single point of measurement exists in the multi-tiered, non-hierarchical topology. Traffic data may be estimated from the aggregate volume through the peering points of the Tier 1 network providers, but traffic that stays local in large provider networks may not be accounted for.[citation needed] An Internet blackout or outage can be caused by local signaling interruptions. Disruptions of submarine communications cables may cause blackouts or slowdowns to large areas, such as in the 2008 submarine cable disruption. Less-developed countries are more vulnerable due to the small number of high-capacity links. Land cables are also vulnerable, as in 2011 when a woman digging for scrap metal severed most connectivity for the nation of Armenia. Internet blackouts affecting almost entire countries can be achieved by governments as a form of Internet censorship, as in the blockage of the Internet in Egypt, whereby approximately 93% of networks were without access in 2011 in an attempt to stop mobilization for anti-government protests. Estimates of the Internet's electricity usage have been the subject of controversy, according to a 2014 peer-reviewed research paper that found claims differing by a factor of 20,000 published in the literature during the preceding decade, ranging from 0.0064 kilowatt hours per gigabyte transferred (kWh/GB) to 136 kWh/GB. The researchers attributed these discrepancies mainly to the year of reference (i.e. whether efficiency gains over time had been taken into account) and to whether "end devices such as personal computers and servers are included" in the analysis. In 2011, academic researchers estimated the overall energy used by the Internet to be between 170 and 307 GW, less than two percent of the energy used by humanity. This estimate included the energy needed to build, operate, and periodically replace the estimated 750 million laptops, a billion smart phones and 100 million servers worldwide as well as the energy that routers, cell towers, optical switches, Wi-Fi transmitters and cloud storage devices use when transmitting Internet traffic. According to a non-peer-reviewed study published in 2018 by The Shift Project (a French think tank funded by corporate sponsors), nearly 4% of global CO2 emissions could be attributed to global data transfer and the necessary infrastructure. The study also said that online video streaming alone accounted for 60% of this data transfer and therefore contributed to over 300 million tons of CO2 emission per year, and argued for new "digital sobriety" regulations restricting the use and size of video files. See also Notes References Sources Further reading External links |
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Contents Animal Animals are multicellular, eukaryotic organisms belonging to the biological kingdom Animalia (/ˌænɪˈmeɪliə/). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor. Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from 8.5 μm (0.00033 in) to 33.6 m (110 ft). They have complex ecologies and interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology, and the study of animal behaviour is known as ethology. The animal kingdom is divided into five major clades, namely Porifera, Ctenophora, Placozoa, Cnidaria and Bilateria. Most living animal species belong to the clade Bilateria, a highly proliferative clade whose members have a bilaterally symmetric and significantly cephalised body plan, and the vast majority of bilaterians belong to two large clades: the protostomes, which includes organisms such as arthropods, molluscs, flatworms, annelids and nematodes; and the deuterostomes, which include echinoderms, hemichordates and chordates, the latter of which contains the vertebrates. The much smaller basal phylum Xenacoelomorpha have an uncertain position within Bilateria. Animals first appeared in the fossil record in the late Cryogenian period and diversified in the subsequent Ediacaran period in what is known as the Avalon explosion. Nearly all modern animal phyla first appeared in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago (Mya), and most classes during the Ordovician radiation 485.4 Mya. Common to all living animals, 6,331 groups of genes have been identified that may have arisen from a single common ancestor that lived about 650 Mya during the Cryogenian period. Historically, Aristotle divided animals into those with blood and those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous with Animalia) and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between taxa. Humans make use of many other animal species for food (including meat, eggs, and dairy products), for materials (such as leather, fur, and wool), as pets and as working animals for transportation, and services. Dogs, the first domesticated animal, have been used in hunting, in security and in warfare, as have horses, pigeons and birds of prey; while other terrestrial and aquatic animals are hunted for sports, trophies or profits. Non-human animals are also an important cultural element of human evolution, having appeared in cave arts and totems since the earliest times, and are frequently featured in mythology, religion, arts, literature, heraldry, politics, and sports. Etymology The word animal comes from the Latin noun animal of the same meaning, which is itself derived from Latin animalis 'having breath or soul'. The biological definition includes all members of the kingdom Animalia. In colloquial usage, the term animal is often used to refer only to nonhuman animals. The term metazoa is derived from Ancient Greek μετα meta 'after' (in biology, the prefix meta- stands for 'later') and ζῷᾰ zōia 'animals', plural of ζῷον zōion 'animal'. A metazoan is any member of the group Metazoa. Characteristics Animals have several characteristics that they share with other living things. Animals are eukaryotic, multicellular, and aerobic, as are plants and fungi. Unlike plants and algae, which produce their own food, animals cannot produce their own food, a feature they share with fungi. Animals ingest organic material and digest it internally. Animals have structural characteristics that set them apart from all other living things: Typically, there is an internal digestive chamber with either one opening (in Ctenophora, Cnidaria, and flatworms) or two openings (in most bilaterians). Animal development is controlled by Hox genes, which signal the times and places to develop structures such as body segments and limbs. During development, the animal extracellular matrix forms a relatively flexible framework upon which cells can move about and be reorganised into specialised tissues and organs, making the formation of complex structures possible, and allowing cells to be differentiated. The extracellular matrix may be calcified, forming structures such as shells, bones, and spicules. In contrast, the cells of other multicellular organisms (primarily algae, plants, and fungi) are held in place by cell walls, and so develop by progressive growth. Nearly all animals make use of some form of sexual reproduction. They produce haploid gametes by meiosis; the smaller, motile gametes are spermatozoa and the larger, non-motile gametes are ova. These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm, also develops between them. These germ layers then differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction generally leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. Some animals are capable of asexual reproduction, which often results in a genetic clone of the parent. This may take place through fragmentation; budding, such as in Hydra and other cnidarians; or parthenogenesis, where fertile eggs are produced without mating, such as in aphids. Ecology Animals are categorised into ecological groups depending on their trophic levels and how they consume organic material. Such groupings include carnivores (further divided into subcategories such as piscivores, insectivores, ovivores, etc.), herbivores (subcategorised into folivores, graminivores, frugivores, granivores, nectarivores, algivores, etc.), omnivores, fungivores, scavengers/detritivores, and parasites. Interactions between animals of each biome form complex food webs within that ecosystem. In carnivorous or omnivorous species, predation is a consumer–resource interaction where the predator feeds on another organism, its prey, who often evolves anti-predator adaptations to avoid being fed upon. Selective pressures imposed on one another lead to an evolutionary arms race between predator and prey, resulting in various antagonistic/competitive coevolutions. Almost all multicellular predators are animals. Some consumers use multiple methods; for example, in parasitoid wasps, the larvae feed on the hosts' living tissues, killing them in the process, but the adults primarily consume nectar from flowers. Other animals may have very specific feeding behaviours, such as hawksbill sea turtles which mainly eat sponges. Most animals rely on biomass and bioenergy produced by plants and phytoplanktons (collectively called producers) through photosynthesis. Herbivores, as primary consumers, eat the plant material directly to digest and absorb the nutrients, while carnivores and other animals on higher trophic levels indirectly acquire the nutrients by eating the herbivores or other animals that have eaten the herbivores. Animals oxidise carbohydrates, lipids, proteins and other biomolecules in cellular respiration, which allows the animal to grow and to sustain basal metabolism and fuel other biological processes such as locomotion. Some benthic animals living close to hydrothermal vents and cold seeps on the dark sea floor consume organic matter produced through chemosynthesis (via oxidising inorganic compounds such as hydrogen sulfide) by archaea and bacteria. Animals originated in the ocean; all extant animal phyla, except for Micrognathozoa and Onychophora, feature at least some marine species. However, several lineages of arthropods begun to colonise land around the same time as land plants, probably between 510 and 471 million years ago, during the Late Cambrian or Early Ordovician. Vertebrates such as the lobe-finned fish Tiktaalik started to move on to land in the late Devonian, about 375 million years ago. Other notable animal groups that colonized land environments are Mollusca, Platyhelmintha, Annelida, Tardigrada, Onychophora, Rotifera, Nematoda. Animals occupy virtually all of earth's habitats and microhabitats, with faunas adapted to salt water, hydrothermal vents, fresh water, hot springs, swamps, forests, pastures, deserts, air, and the interiors of other organisms. Animals are however not particularly heat tolerant; very few of them can survive at constant temperatures above 50 °C (122 °F) or in the most extreme cold deserts of continental Antarctica. The collective global geomorphic influence of animals on the processes shaping the Earth's surface remains largely understudied, with most studies limited to individual species and well-known exemplars. Diversity The blue whale (Balaenoptera musculus) is the largest animal that has ever lived, weighing up to 190 tonnes and measuring up to 33.6 metres (110 ft) long. The largest extant terrestrial animal is the African bush elephant (Loxodonta africana), weighing up to 12.25 tonnes and measuring up to 10.67 metres (35.0 ft) long. The largest terrestrial animals that ever lived were titanosaur sauropod dinosaurs such as Argentinosaurus, which may have weighed as much as 73 tonnes, and Supersaurus which may have reached 39 metres. Several animals are microscopic; some Myxozoa (obligate parasites within the Cnidaria) never grow larger than 20 μm, and one of the smallest species (Myxobolus shekel) is no more than 8.5 μm when fully grown. The following table lists estimated numbers of described extant species for the major animal phyla, along with their principal habitats (terrestrial, fresh water, and marine), and free-living or parasitic ways of life. Species estimates shown here are based on numbers described scientifically; much larger estimates have been calculated based on various means of prediction, and these can vary wildly. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of the total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million. Using patterns within the taxonomic hierarchy, the total number of animal species—including those not yet described—was calculated to be about 7.77 million in 2011.[a] 3,000–6,500 4,000–25,000 Evolutionary origin Evidence of animals is found as long ago as the Cryogenian period. 24-Isopropylcholestane (24-ipc) has been found in rocks from roughly 650 million years ago; it is only produced by sponges and pelagophyte algae. Its likely origin is from sponges based on molecular clock estimates for the origin of 24-ipc production in both groups. Analyses of pelagophyte algae consistently recover a Phanerozoic origin, while analyses of sponges recover a Neoproterozoic origin, consistent with the appearance of 24-ipc in the fossil record. The first body fossils of animals appear in the Ediacaran, represented by forms such as Charnia and Spriggina. It had long been doubted whether these fossils truly represented animals, but the discovery of the animal lipid cholesterol in fossils of Dickinsonia establishes their nature. Animals are thought to have originated under low-oxygen conditions, suggesting that they were capable of living entirely by anaerobic respiration, but as they became specialised for aerobic metabolism they became fully dependent on oxygen in their environments. Many animal phyla first appear in the fossil record during the Cambrian explosion, starting about 539 million years ago, in beds such as the Burgess Shale. Extant phyla in these rocks include molluscs, brachiopods, onychophorans, tardigrades, arthropods, echinoderms and hemichordates, along with numerous now-extinct forms such as the predatory Anomalocaris. The apparent suddenness of the event may however be an artefact of the fossil record, rather than showing that all these animals appeared simultaneously. That view is supported by the discovery of Auroralumina attenboroughii, the earliest known Ediacaran crown-group cnidarian (557–562 mya, some 20 million years before the Cambrian explosion) from Charnwood Forest, England. It is thought to be one of the earliest predators, catching small prey with its nematocysts as modern cnidarians do. Some palaeontologists have suggested that animals appeared much earlier than the Cambrian explosion, possibly as early as 1 billion years ago. Early fossils that might represent animals appear for example in the 665-million-year-old rocks of the Trezona Formation of South Australia. These fossils are interpreted as most probably being early sponges. Trace fossils such as tracks and burrows found in the Tonian period (from 1 gya) may indicate the presence of triploblastic worm-like animals, roughly as large (about 5 mm wide) and complex as earthworms. However, similar tracks are produced by the giant single-celled protist Gromia sphaerica, so the Tonian trace fossils may not indicate early animal evolution. Around the same time, the layered mats of microorganisms called stromatolites decreased in diversity, perhaps due to grazing by newly evolved animals. Objects such as sediment-filled tubes that resemble trace fossils of the burrows of wormlike animals have been found in 1.2 gya rocks in North America, in 1.5 gya rocks in Australia and North America, and in 1.7 gya rocks in Australia. Their interpretation as having an animal origin is disputed, as they might be water-escape or other structures. Phylogeny Animals are monophyletic, meaning they are derived from a common ancestor. Animals are the sister group to the choanoflagellates, with which they form the Choanozoa. Ros-Rocher and colleagues (2021) trace the origins of animals to unicellular ancestors, providing the external phylogeny shown in the cladogram. Uncertainty of relationships is indicated with dashed lines. The animal clade had certainly originated by 650 mya, and may have come into being as much as 800 mya, based on molecular clock evidence for different phyla. Holomycota (inc. fungi) Ichthyosporea Pluriformea Filasterea The relationships at the base of the animal tree have been debated. Other than Ctenophora, the Bilateria and Cnidaria are the only groups with symmetry, and other evidence shows they are closely related. In addition to sponges, Placozoa has no symmetry and was often considered a "missing link" between protists and multicellular animals. The presence of hox genes in Placozoa shows that they were once more complex. The Porifera (sponges) have long been assumed to be sister to the rest of the animals, but there is evidence that the Ctenophora may be in that position. Molecular phylogenetics has supported both the sponge-sister and ctenophore-sister hypotheses. In 2017, Roberto Feuda and colleagues, using amino acid differences, presented both, with the following cladogram for the sponge-sister view that they supported (their ctenophore-sister tree simply interchanging the places of ctenophores and sponges): Porifera Ctenophora Placozoa Cnidaria Bilateria Conversely, a 2023 study by Darrin Schultz and colleagues uses ancient gene linkages to construct the following ctenophore-sister phylogeny: Ctenophora Porifera Placozoa Cnidaria Bilateria Sponges are physically very distinct from other animals, and were long thought to have diverged first, representing the oldest animal phylum and forming a sister clade to all other animals. Despite their morphological dissimilarity with all other animals, genetic evidence suggests sponges may be more closely related to other animals than the comb jellies are. Sponges lack the complex organisation found in most other animal phyla; their cells are differentiated, but in most cases not organised into distinct tissues, unlike all other animals. They typically feed by drawing in water through pores, filtering out small particles of food. The Ctenophora and Cnidaria are radially symmetric and have digestive chambers with a single opening, which serves as both mouth and anus. Animals in both phyla have distinct tissues, but these are not organised into discrete organs. They are diploblastic, having only two main germ layers, ectoderm and endoderm. The tiny placozoans have no permanent digestive chamber and no symmetry; they superficially resemble amoebae. Their phylogeny is poorly defined, and under active research. The remaining animals, the great majority—comprising some 29 phyla and over a million species—form the Bilateria clade, which have a bilaterally symmetric body plan. The Bilateria are triploblastic, with three well-developed germ layers, and their tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and in the Nephrozoa there is an internal body cavity, a coelom or pseudocoelom. These animals have a head end (anterior) and a tail end (posterior), a back (dorsal) surface and a belly (ventral) surface, and a left and a right side. A modern consensus phylogenetic tree for the Bilateria is shown below. Xenacoelomorpha Ambulacraria Chordata Ecdysozoa Spiralia Having a front end means that this part of the body encounters stimuli, such as food, favouring cephalisation, the development of a head with sense organs and a mouth. Many bilaterians have a combination of circular muscles that constrict the body, making it longer, and an opposing set of longitudinal muscles, that shorten the body; these enable soft-bodied animals with a hydrostatic skeleton to move by peristalsis. They also have a gut that extends through the basically cylindrical body from mouth to anus. Many bilaterian phyla have primary larvae which swim with cilia and have an apical organ containing sensory cells. However, over evolutionary time, descendant spaces have evolved which have lost one or more of each of these characteristics. For example, adult echinoderms are radially symmetric (unlike their larvae), while some parasitic worms have extremely simplified body structures. Genetic studies have considerably changed zoologists' understanding of the relationships within the Bilateria. Most appear to belong to two major lineages, the protostomes and the deuterostomes. It is often suggested that the basalmost bilaterians are the Xenacoelomorpha, with all other bilaterians belonging to the subclade Nephrozoa. However, this suggestion has been contested, with other studies finding that xenacoelomorphs are more closely related to Ambulacraria than to other bilaterians. Protostomes and deuterostomes differ in several ways. Early in development, deuterostome embryos undergo radial cleavage during cell division, while many protostomes (the Spiralia) undergo spiral cleavage. Animals from both groups possess a complete digestive tract, but in protostomes the first opening of the embryonic gut develops into the mouth, and the anus forms secondarily. In deuterostomes, the anus forms first while the mouth develops secondarily. Most protostomes have schizocoelous development, where cells simply fill in the interior of the gastrula to form the mesoderm. In deuterostomes, the mesoderm forms by enterocoelic pouching, through invagination of the endoderm. The main deuterostome taxa are the Ambulacraria and the Chordata. Ambulacraria are exclusively marine and include acorn worms, starfish, sea urchins, and sea cucumbers. The chordates are dominated by the vertebrates (animals with backbones), which consist of fishes, amphibians, reptiles, birds, and mammals. The protostomes include the Ecdysozoa, named after their shared trait of ecdysis, growth by moulting, Among the largest ecdysozoan phyla are the arthropods and the nematodes. The rest of the protostomes are in the Spiralia, named for their pattern of developing by spiral cleavage in the early embryo. Major spiralian phyla include the annelids and molluscs. History of classification In the classical era, Aristotle divided animals,[d] based on his own observations, into those with blood (roughly, the vertebrates) and those without. The animals were then arranged on a scale from man (with blood, two legs, rational soul) down through the live-bearing tetrapods (with blood, four legs, sensitive soul) and other groups such as crustaceans (no blood, many legs, sensitive soul) down to spontaneously generating creatures like sponges (no blood, no legs, vegetable soul). Aristotle was uncertain whether sponges were animals, which in his system ought to have sensation, appetite, and locomotion, or plants, which did not: he knew that sponges could sense touch and would contract if about to be pulled off their rocks, but that they were rooted like plants and never moved about. In 1758, Carl Linnaeus created the first hierarchical classification in his Systema Naturae. In his original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then, the last four have all been subsumed into a single phylum, the Chordata, while his Insecta (which included the crustaceans and arachnids) and Vermes have been renamed or broken up. The process was begun in 1793 by Jean-Baptiste de Lamarck, who called the Vermes une espèce de chaos ('a chaotic mess')[e] and split the group into three new phyla: worms, echinoderms, and polyps (which contained corals and jellyfish). By 1809, in his Philosophie Zoologique, Lamarck had created nine phyla apart from vertebrates (where he still had four phyla: mammals, birds, reptiles, and fish) and molluscs, namely cirripedes, annelids, crustaceans, arachnids, insects, worms, radiates, polyps, and infusorians. In his 1817 Le Règne Animal, Georges Cuvier used comparative anatomy to group the animals into four embranchements ('branches' with different body plans, roughly corresponding to phyla), namely vertebrates, molluscs, articulated animals (arthropods and annelids), and zoophytes (radiata) (echinoderms, cnidaria and other forms). This division into four was followed by the embryologist Karl Ernst von Baer in 1828, the zoologist Louis Agassiz in 1857, and the comparative anatomist Richard Owen in 1860. In 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms: Metazoa (multicellular animals, with five phyla: coelenterates, echinoderms, articulates, molluscs, and vertebrates) and Protozoa (single-celled animals), including a sixth animal phylum, sponges. The protozoa were later moved to the former kingdom Protista, leaving only the Metazoa as a synonym of Animalia. In human culture The human population exploits a large number of other animal species for food, both of domesticated livestock species in animal husbandry and, mainly at sea, by hunting wild species. Marine fish of many species are caught commercially for food. A smaller number of species are farmed commercially. Humans and their livestock make up more than 90% of the biomass of all terrestrial vertebrates, and almost as much as all insects combined. Invertebrates including cephalopods, crustaceans, insects—principally bees and silkworms—and bivalve or gastropod molluscs are hunted or farmed for food, fibres. Chickens, cattle, sheep, pigs, and other animals are raised as livestock for meat across the world. Animal fibres such as wool and silk are used to make textiles, while animal sinews have been used as lashings and bindings, and leather is widely used to make shoes and other items. Animals have been hunted and farmed for their fur to make items such as coats and hats. Dyestuffs including carmine (cochineal), shellac, and kermes have been made from the bodies of insects. Working animals including cattle and horses have been used for work and transport from the first days of agriculture. Animals such as the fruit fly Drosophila melanogaster serve a major role in science as experimental models. Animals have been used to create vaccines since their discovery in the 18th century. Some medicines such as the cancer drug trabectedin are based on toxins or other molecules of animal origin. People have used hunting dogs to help chase down and retrieve animals, and birds of prey to catch birds and mammals, while tethered cormorants have been used to catch fish. Poison dart frogs have been used to poison the tips of blowpipe darts. A wide variety of animals are kept as pets, from invertebrates such as tarantulas, octopuses, and praying mantises, reptiles such as snakes and chameleons, and birds including canaries, parakeets, and parrots all finding a place. However, the most kept pet species are mammals, namely dogs, cats, and rabbits. There is a tension between the role of animals as companions to humans, and their existence as individuals with rights of their own. A wide variety of terrestrial and aquatic animals are hunted for sport. The signs of the Western and Chinese zodiacs are based on animals. In China and Japan, the butterfly has been seen as the personification of a person's soul, and in classical representation the butterfly is also the symbol of the soul. Animals have been the subjects of art from the earliest times, both historical, as in ancient Egypt, and prehistoric, as in the cave paintings at Lascaux. Major animal paintings include Albrecht Dürer's 1515 The Rhinoceros, and George Stubbs's c. 1762 horse portrait Whistlejacket. Insects, birds and mammals play roles in literature and film, such as in giant bug movies. Animals including insects and mammals feature in mythology and religion. The scarab beetle was sacred in ancient Egypt, and the cow is sacred in Hinduism. Among other mammals, deer, horses, lions, bats, bears, and wolves are the subjects of myths and worship. See also Notes References External links |
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[SOURCE: https://en.wikipedia.org/wiki/History_of_the_Jews_in_Qatar] | [TOKENS: 1919] |
Contents History of the Jews in Qatar The history of the Jews in Qatar is relatively limited unlike some of the neighboring countries in the Gulf of Persia. In modern days a small number of immigrants of Jewish descent reside in Qatar, mainly in the capital Doha. Kosher food was produced during the 2022 World Cup and Rabbi Eli Chitrik visits Qatar several times a year on behalf of the Alliance of Rabbis in Islamic States. Jews and Judaism in Qatar In 2005 Qatar University with the Qatari Ministry of Foreign Affairs invited a Jewish delegation from Israel to take part in an international conference on religious dialogue despite opposition from some quarters. It was the first time that Jewish scholars attended the International Conference on Religious Dialogue held every year in Qatar. Various Jewish people visit and live in Qatar. Professor Gary Wasserman wrote a book The Doha Experiment: Arab Kingdom, Catholic College, Jewish Teacher describing his stay teaching and working in Qatar where Wasserman encountered barely any personal animosity due to being Jewish. In 2013 Qatar assisted Yemenite Jews to move to Israel. The first group of Yemenite Jews departed from Doha on Qatari flights and arrived in Tel Aviv's Ben Gurion International Airport. A significant sign of Qatar's new openness to outsiders that includes Jews was that over 10,000 Israelis and many other Jews visited for the 2022 FIFA World Cup many of whom were provided with tens of thousands of Kosher meals showing that there is official recognition and permission to practice Judaism. As early as 2019 it was reported that Qatari officials had consulted with American Rabbi Marc Schneier as to how to welcome the thousands of Israelis and Jews who intended to attend the world Cup finals in 2022. In 2021 the Association of Gulf Jewish Communities was established to serve Jewish populations in Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates. A 2023 report by the United States Department of State stated that during Ramadan the US ambassador hosted an interfaith Suhur (morning meal before sunrise or after the fast-breaking evening meal during Ramadan) bringing together Muslim, Christian, and Jewish representatives and in September, the US embassy helped facilitate the visit of a rabbi who conducted Jewish religious services. In a strange twist, rabbis from the anti-Zionist Jewish movement Neturei Karta attended the funeral of Hamas political bureau chief Ismail Haniyeh in the Qatari capital Doha in 2024. Some reports suggest that Qatar's recent official benevolence and tolerance of Jews and Judaism inside Qatar itself is aimed at easing its political isolation and improving its own image by reaching out to American Jews. Qatar's efforts to reach out to wealthy and influentuel American Jews was reported by Axios in 2023: "Jared Kushner and Ivanka Trump organized a private meeting in New York last Wednesday with Qatar's prime minister and a bipartisan group mostly of Jewish businessmen and billionaires, three sources with direct knowledge of the meeting tell Axios." In a 2023 report by the Board of Deputies of British Jews a delegation of World Jewish Congress officials, led by its president Ronald Lauder, engaged in discussions with leaders in Qatar. During these high-level meetings the concerns of global Jewry regarding the plight of Israeli hostages in Gaza were expressed seeking the intervention of Arab leaders to secure the release of the Israeli hostages. Qatar and accusations of Antisemitism Antisemitism is rife in many areas of life in Qatar, alongside Kuwait, Oman, Malaysia and other Arab and Muslim countries as well as fostering antisemitism beyond its borders. The media giant Al Jazeera is based in Qatar and has frequently been accused of fostering and spouting antisemitism. Antisemitic cartoons appear often in Qatari newspapers and school books. The United States Department of State has found persistent antisemitism in Qatari school textbooks such as that Jews seek world domination. Some writers have called for a cut-off of funding to American colleges by Qatar, Saudi Arabia, Kuwait and other wealthy Arab and Muslim countries because the multimillion-dollar donations to Middle Eastern studies centers and departments have advanced Islamist ideology and fostered Jew-hatred at U.S. universities. Qatar has allegedly supplied money for antisemitic activists and activism against Jewish students and Jewish interests on American college and university campuses. Some American politicians have spoken out against the antisemitic outcomes of Qatari funding of US institutions, such as Representative Jack Bergman, who has stated that: "For years, the Qatar Foundation philanthropies and the Qatar Investment Authority have played a key role in the organization and funding of the radical antisemitic Boycott, Divestment and Sanctions movement on U.S. college campuses. Since 2017, Qatar has hired at least 100 different firms for lobbying and public relations, according to the Foreign Agents Registration Act database. Qatar has also lavished tens of millions of dollars on nonprofit Washington think tanks, including the Brookings Institution. And Qatar has given over $5 billion to U.S. universities, according to records published by the U.S. Department of Education." In 2016 the Simon Wiesenthal Center objected to the continued display of titles inciting to hatred of Jews at the Doha International Book Fair. A 2024 first ever Web Summit Qatar bringing together thousands of investors and startups was also tainted with antisemitism due to a large number of investors and tech experts advertised as speaking at the Doha conference who are on record of promoting antisemitic tropes. Even though Qatar has been a mediator in the 2024 Gaza war, it has nevertheless been accused of antisemitism in the process. Forum on US-Islamic relations As an indication of the opening up of Qatari society to western influence and giving appropriate attention to the Jewish population, the Jewish Telegraphic Agency reported in December 2003 that a forum on U.S.-Islamic relations in Qatar would feature both Israeli and U.S. Jewish participants. Former president Clinton and Sheikh Hamad Bin Khalifa Al-Thani, the emir of Qatar, were the scheduled keynote speakers at the 2004 US-Islamic Forum in Doha. The forum was sponsored by the Project on US Policy Towards the Islamic World and funded by the Saban Center, founded by American-Israeli entertainment mogul Haim Saban. Participants came from predominantly Islamic countries, including Syria, Saudi Arabia, and Sudan. Martin Kramer, the editor of the Middle East Quarterly, was the sole Israeli participant since Saban and attended as an American. Jewish-American soldiers A news report that described the preparations for U.S. troops stationed in Qatar: The Jewish members of America's armed forces will again receive kosher K-rations this Pesach throughout the holiday, provided by the U.S. Defense Department. Thousands of packages containing kosher for Pesach MREs (meals ready to eat) have already reached U.S. army and navy supply bases, with special shipments aimed at Jewish troops in Iraq and Afghanistan... The Jewish Chaplains Council estimates that the number of Jews stationed in Iraq is between 500 and 600. Of the 30 Jewish chaplains on active duty worldwide, eight chaplains are stationed in Iraq, including two female rabbis. Each chaplain stationed in Iraq will hold two seders at base camps, with central seders in Baghdad, Falluja, and Tikrit. There will also be two seders at the army headquarters in Bahrain, and air force headquarters in Qatar. Jewish soldiers stationed in remote locations will be able to attend seders led by soldiers who received special training for that purpose. Diplomatic openings In 2007 a report stated, Arab states, led by Saudi Arabia, are making some of their most public overtures ever to Israel and American Jews to undercut Iran's growing influence, contain violence in Iraq and Lebanon and push for a Palestinian solution...Saudi Arabia, Qatar, and the United Arab Emirates have stepped up contacts with Israel and pro-Israel Jewish groups in the USA. The outreach has the Bush administration's blessing: Secretary of State Condoleezza Rice has said six Persian Gulf states and Egypt, Jordan, and Israel are a new alignment of moderates to oppose extremists backed by Iran and Syria. She has said an Israeli-Palestinian peace deal would weaken militants such as Hamas and Hezbollah...Saudi and Gulf Arab contacts with Israelis and American Jews go back more than a decade but have never been so public. Arab countries have treated Israel as a pariah since it gained independence in 1948. Most Arab countries ban travel to Israel, investment there, and other commercial ties with the Jewish state and routinely refer to it as the "Zionist entity." ...Among the other recent Arab-Jewish contacts: Saudi national security adviser Bandar bin Sultan met privately with Israeli prime minister Ehud Olmert in Jordan in September, said Daniel Ayalon, Israel's former ambassador to Washington. He said it was the highest-level Saudi-Israeli meeting he'd ever heard of. The United Arab Emirates has invited a delegation from the Conference of Presidents of Major American Jewish Organizations. The conference, a 51-member umbrella group, is a strong supporter of Israel. Israeli deputy prime minister Shimon Peres met the emir of Qatar in late January after taking part in a debate with Arab students there. It was the highest-level Israeli meeting with the Persian Gulf nation since 1996 when Peres visited as prime minister." Jews in the Arabian Peninsula See also References |
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[SOURCE: https://en.wikipedia.org/wiki/Habitability_of_yellow_dwarf_systems] | [TOKENS: 2711] |
Contents Habitability of G-type main-sequence star systems Habitability of yellow dwarf systems defines the suitability for life of exoplanets belonging to yellow dwarf stars. These systems are the object of study among the scientific community because they are considered the most suitable for harboring living organisms, together with those belonging to K-type stars. Yellow dwarfs comprise the G-type stars of the main sequence, with masses between 0.9 and 1.1 M☉ and surface temperatures between 5000 and 6000 K, like the Sun. They are the third most common in the Milky Way Galaxy and the only ones in which the habitable zone coincides completely with the ultraviolet habitable zone. Since the habitable zone is farther away in more massive and luminous stars, the separation between the main star and the inner edge of this region is greater in yellow dwarfs than in red and orange dwarfs. Therefore, planets located in this zone of G-type stars are safe from the intense stellar emissions that occur after their formation and are not as affected by the gravitational influence of their star as those belonging to smaller stellar bodies. Thus, all planets in the habitable zone of such stars exceed the tidal locking limit and their rotation is therefore not synchronized with their orbit. The Earth, orbiting a yellow dwarf, represents the only known example of planetary habitability. For this reason, the main goal in the field of exoplanetology is to find an Earth analog planet that meets its main characteristics, such as size, average temperature and location around a star similar to the Sun. However, technological limitations make it difficult to find these objects due to either the infrequency of their transits or their small radial-velocity semi-amplitudes, both are consequences of the distance that separates them from their stars or semi-major axis. Characteristics Yellow dwarf stars correspond to the G-class stars of the main sequence, with a mass between 0.9 and 1.1 M☉, and surface temperatures between 5000 and 6000 K. Since the Sun itself is a yellow dwarf, of type G2V, these types of stars are also known as solar analogs. They rank third among the most common main sequence stars, after red and orange dwarfs, with a representativeness of 10% of the total Milky Way. They remain in the main sequence for approximately 10 billion years. After the Sun, the closest G-type star to the Earth is Alpha Centauri A, 4.4 light-years away and belonging to a multiple star system. All stars go through a phase of intense activity after their formation due to their rotation, which is much faster at the beginning of their lives. The duration of this period varies according to the mass of the object: the least massive stars can remain in this state for up to 3 billion years, compared to 500 million for G-type stars. Studies by the team of Edward Guinan, an astrophysicist at Villanova University, reveal that the Sun rotated ten times faster in its early days. Since the rotation speed of a star affects its magnetic field, the Sun's X-ray and UV emissions were hundreds of times more intense than they are today. The extension of this phase in red dwarfs, as well as the probable tidal locking of their potentially habitable planets with respect to them, could wipe out the magnetic field of these planets, resulting in the loss of almost all their atmosphere and water to space by interaction with the stellar wind. In contrast, the semi-major axis of planetary objects belonging to the habitable zone of G-type stars is wide enough to allow planetary rotation. In addition, the duration of the period of intense stellar activity is too short to eliminate a significant part of the atmosphere on planets with masses similar to or greater than that of the Earth, which have a gravity and magnetosphere capable of counteracting the effects of stellar winds. Habitable area The habitable zone around yellow dwarfs varies according to their size and luminosity, although the inner boundary is usually at 0.84 AU and the outer one at 1.67 in a G2V class dwarf like the Sun. For a G5V class star with a radius of 0.95 R☉—smaller than the Sun—the habitable zone would correspond to the region located between 0.8 and 1.58 AU with respect to the star. For a G0V star—larger than the Sun—it would be located at a distance of between 1 and 2 AU from the stellar body. In orbits smaller than the inner boundary of the habitable zone, a process of water evaporation, hydrogen separation by photolysis and loss of hydrogen to space by hydrodynamic escape would be triggered. Beyond the outer limit of the habitable zone, temperatures would be low enough to allow CO2 condensation, which would lead to an increase in albedo and a feedback reduction of the greenhouse effect until a permanent global glaciation would occur. The size of the habitable zone is directly proportional to the mass and luminosity of its star, so the larger the star, the larger the habitable zone and the farther from its surface. Red dwarfs, the smallest of the main sequence, have a very small habitable zone close to them, which subjects any potentially habitable planets in the system to the effects of their star, including probable tidal locking. Even in a small yellow dwarf like Tau Ceti, of type G8.5V, the locking limit is at 0.4237 AU versus the 0.522 AU that marks the inner boundary of the habitable zone, so any planetary object orbiting a G-class star in this region will far exceed the locking limit, and will have day-night cycles like Earth. In yellow dwarfs, this region coincides entirely with the ultraviolet habitability zone. This area is determined by an inner limit beyond which exposure to ultraviolet radiation would be too high for DNA and by an outer limit that provides the minimum levels for living things to carry out their biogenic processes. In the Solar System, this region is located between 0.71 and 1.9 AU with respect to the Sun, compared to the 0.84–1.67 AU that mark the extremes of the habitable zone. Life potential Given the length of the main sequence in G-type stars, the levels of ultraviolet radiation in their habitable zone, the semi-major axis of the inner boundary of this region and the distance to their tidal locking limit, among other factors, yellow dwarfs are considered to be the most hospitable to life next to K-type stars. One goal in exoplanetary research is to find an object that has the main characteristics of our planet, such as radius, mass, temperature, atmospheric composition and belonging to a star similar to the Sun. In theory, these Earth analogs should have comparable habitability conditions that would allow the proliferation of extraterrestrial life. Based on the serious problems for planetary habitability presented by red dwarf systems and stellar bodies of type F or higher, the only stars that might offer a bearable scenario for life would be those of type K and G. Solar analogs used to be considered as the most likely candidates to host a solar-like planetary system, and as the best positioned to support carbon-based life forms and liquid water oceans. Subsequent studies, such as "Superhabitable Worlds" by René Heller and John Armstrong, establish that orange dwarfs may be more suitable for life than G-type dwarfs, and host hypothetical superhabitable planets. However, yellow dwarfs still represent the only stellar type for which there is evidence of their suitability for life. Moreover, while in other types of stars the habitable zone does not coincide entirely with the ultraviolet habitable zone, in G-class stars the habitable zone lies entirely within the limits of the latter. Finally, yellow dwarfs have a much shorter initial phase of intense stellar activity than K-type and M-type stars, which allows planets belonging to solar analogs to preserve their primordial atmospheres more easily and to maintain them for much of the main sequence. Discoveries Most of the exoplanets discovered have been detected by the Kepler space telescope, which uses the transit method to find planets around other systems. This procedure analyzes the brightness of stars to detect dips that indicate the passage of a planetary object in front of them from the perspective of the observatory. It is the method that has been most successful in exoplanetary research, together with the radial velocity method, which consists of analyzing the vibrations caused in the stars by the gravitational effects of the planets orbiting them. The use of these procedures with the limitations of current telescopes makes it difficult to find objects with orbits similar to the Earth's orbits or higher, which generates a bias in favor of planets with a short semi-major axis. As a consequence, most of the exoplanets detected are either excessively hot or belong to low-mass stars, whose habitable zone is close to them and any object orbiting in this region will have a significantly shorter year than the Earth. Planetary bodies belonging to the habitable zone of yellow dwarfs, such as Kepler-22b, 82 G. Eridani d or Earth, take hundreds of days to complete an orbit around their star. The higher luminosity of these stars, the scarcity of transits and the semi-major axis of their planets located in the habitable zone reduce the probabilities of detecting this class of objects and considerably increase the number of false positives, as in the cases of KOI-5123.01 and KOI-5927.01. The ground-based and orbital observatories projected for the next ten years may increase the discoveries of Earth analogs in yellow dwarf systems. Kepler-452b lies 1400 light-years from Earth, in the Cygnus constellation. Its radius of about 1.6 R⊕ places it right on the boundary separating telluric planets from mini-Neptunes established by the team of Courtney Dressing, a researcher at the Harvard-Smithsonian Center for Astrophysics (CfA). If the planet's density is similar to Earth's, its mass will be about 5 M⊕ and its gravity twice as great. A G2V-type yellow dwarf like the Sun belongs to Kepler-452, with an estimated age of 6 billion years (6 Ga) versus the solar system's 4.5 Ga. The mass of its star is slightly higher than that of the Sun, 1.04 M☉, so despite the fact that it completes an orbit around it every 385 days versus 365 terrestrial days, it is warmer than the Earth. If it has similar albedo and atmospheric composition, the average surface temperature will be around 29 °C. According to Jon Jenkins of NASA's Ames Research Center, it is not known whether Kepler-452b is a terrestrial planet, an ocean world or a mini-Neptune. If it is an Earth-like telluric object, it is likely to have a higher concentration of clouds, intense volcanic activity, and is about to suffer an uncontrolled greenhouse effect similar to that of Venus due to the constant increase in the luminosity of its star, after having remained throughout the main sequence in its habitable zone. Doug Caldwell, a SETI Institute scientist and member of the Kepler mission, estimates that Kepler-452b may be undergoing the same process that the Earth will undergo in a billion years. Tau Ceti e orbits a G8.5V-type star in the constellation Cetus, 12 light-years from Earth. It has a radius of 1.59 R⊕ and a mass of 4.29 M⊕, so like Kepler-452b it lies at the separation boundary between terrestrial and gaseous planets. With an orbital period of only 168 days, its temperature assuming an Earth-like atmospheric composition and albedo would be about 50 °C. The planet is located just at the inner edge of the habitable zone and receives about 60% more light than Earth. Its size may also imply a higher concentration of gases in its atmosphere, making it a super-Venus type object. Otherwise, it could be the first thermoplanet discovered. Kepler-22b is at a distance of 600 light-years, in the Cygnus constellation. It completes one orbit around its G5V-type star every 290 days. Its radius is 2.35 R⊕ and its estimated mass, for an Earth-like density, would be 20.36 M⊕. If the planet's atmosphere and albedo were similar to Earth's, its surface temperature would be around 22 °C. It was the first exoplanet found by the Kepler telescope belonging to the habitability zone of its star. Because of its size, considering the limit established by Courtney Dressing's team, its probability to be a mini-Neptune is very high. In October 2024, the existence of a temperate 6.4-Earth mass planet orbiting the G-type star HD 20794 (at 19.7 light-years away) was confirmed. This planet orbits partially exterior to the circumstellar habitable zone. See also References Bibliography |
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[SOURCE: https://en.wikipedia.org/wiki/Star_cluster] | [TOKENS: 2375] |
Contents Star cluster A star cluster is a group of stars, that share an origin, formed at roughly the same time and held together by self-gravitation. Two main types of star clusters can be distinguished: globular clusters, tight groups of ten thousand to millions of old stars which are gravitationally bound; and open clusters, less tight groups of stars, generally containing fewer than a few hundred members. As they move through their galaxy, over time, open clusters become disrupted by the gravitational influence of giant molecular clouds, so that the clusters observed are often young. Even though no longer gravitationally bound, they will continue to move in broadly the same direction through space and are then known as stellar associations, sometimes referred to as moving groups. Globular clusters, with more members and more mass, remain intact for far longer and the globular clusters observed are usually billions of years old. Star clusters within the Milky Way that are visible to the naked eye, include the Pleiades and Hyades open clusters, and the globular cluster 47 Tucanae. Open cluster Open clusters are confined to the galactic plane, and are almost always found within spiral arms. They are generally young objects, up to a few tens of millions of years old, with a few rare exceptions as old as a few billion years, such as Messier 67 (the closest and most observed old open cluster) for example. They form in H II regions such as the Orion Nebula. Open clusters typically have a few hundred members and are located in an area up to 30 light-years across. Being much less densely populated than globular clusters, they are much less tightly gravitationally bound, and over time, are disrupted by the gravity of giant molecular clouds and other clusters. Close encounters between cluster members can also result in the ejection of stars, a process known as "evaporation". The most prominent open clusters are the Pleiades and Hyades in Taurus. The Double Cluster of h+Chi Persei can also be prominent under dark skies. Open clusters are often dominated by hot young blue stars, because although such stars are short-lived in stellar terms, only lasting a few tens of millions of years, open clusters tend to have dispersed before these stars die. A subset of open clusters constitute a binary or aggregate cluster. New research indicates Messier 25 may constitute a ternary star cluster together with NGC 6716 and Collinder 394. Establishing precise distances to open clusters enables the calibration of the period-luminosity relationship shown by Cepheids variable stars, which are then used as standard candles. Cepheids are luminous and can be used to establish both the distances to remote galaxies and the expansion rate of the Universe (Hubble constant). Indeed, the open cluster NGC 7790 hosts three classical Cepheids which are critical for such efforts. Embedded clusters are groups of very young stars that are partially or fully encased in interstellar dust or gas which is often impervious to optical observations. Embedded clusters form in molecular clouds, when the clouds begin to collapse and form stars. There is often ongoing star formation in these clusters, so embedded clusters may be home to various types of young stellar objects including protostars and pre-main-sequence stars. An example of an embedded cluster is the Trapezium Cluster in the Orion Nebula. In ρ Ophiuchi cloud (L1688) core region there is an embedded cluster. The embedded cluster phase may last for several million years, after which gas in the cloud is depleted by star formation or dispersed through radiation pressure, stellar winds and outflows, or supernova explosions. In general less than 30% of cloud mass is converted to stars before the cloud is dispersed, but this fraction may be higher in particularly dense parts of the cloud. With the loss of mass in the cloud, the energy of the system is altered, often leading to the disruption of a star cluster. Most young embedded clusters disperse shortly after the end of star formation. The open clusters found in the Galaxy are former embedded clusters that were able to survive early cluster evolution. However, nearly all freely floating stars, including the Sun, were originally born into embedded clusters that disintegrated. Globular cluster Globular clusters are roughly spherical groupings ranging from 10 thousand to several million stars packed into regions ranging from 10 to 30 light-years across. They commonly consist of very old Population II stars – just a few hundred million years younger than the universe itself – which are mostly yellow and red, with masses less than two solar masses. Such stars predominate within clusters because hotter and more massive stars have exploded as supernovae, or evolved through planetary nebula phases to end as white dwarfs. Yet a few rare blue stars exist in globulars, thought to be formed by stellar mergers in their dense inner regions; these stars are known as blue stragglers. In the Milky Way galaxy, globular clusters are distributed roughly spherically in the galactic halo, around the Galactic Center, orbiting the center in highly elliptical orbits. In 1917, the astronomer Harlow Shapley made the first respectable estimate of the Sun's distance from the Galactic Center, based on the distribution of globular clusters. Until the mid-1990s, globular clusters were the cause of a great mystery in astronomy, as theories of stellar evolution gave ages for the oldest members of globular clusters that were greater than the estimated age of the universe. However, greatly improved distance measurements to globular clusters using the Hipparcos satellite and increasingly accurate measurements of the Hubble constant resolved the paradox, giving an age for the universe of about 13 billion years and an age for the oldest stars of a few hundred million years less. Our Galaxy has about 150 globular clusters, some of which may have been captured cores of small galaxies stripped of stars previously in their outer margins by the tides of the Milky Way, as seems to be the case for the globular cluster M79. Some galaxies are much richer in globulars than the Milky Way: The giant elliptical galaxy M87 contains over a thousand. A few of the brightest globular clusters are visible to the naked eye; the brightest, Omega Centauri, was observed in antiquity and catalogued as a star, before the telescopic age. The brightest globular cluster in the northern hemisphere is M13 in the constellation of Hercules. Super star cluster Super star clusters are very large regions of recent star formation, and are thought to be the precursors of globular clusters. Examples include Westerlund 1 in the Milky Way. Intermediate forms In 2005, astronomers discovered a new type of star cluster in the Andromeda Galaxy, which is, in several ways, very similar to globular clusters although less dense. No such clusters (which also known as extended globular clusters) are known in the Milky Way. The three discovered in Andromeda Galaxy are M31WFS C1 M31WFS C2, and M31WFS C3. These new-found star clusters contain hundreds of thousands of stars, a similar number to globular clusters. The clusters also share other characteristics with globular clusters, e.g. the stellar populations and metallicity. What distinguishes them from the globular clusters is that they are much larger – several hundred light-years across – and hundreds of times less dense. The distances between the stars are thus much greater. The clusters have properties intermediate between globular clusters and dwarf spheroidal galaxies. How these clusters are formed is not yet known, but their formation might well be related to that of globular clusters. Why M31 has such clusters, while the Milky Way has not, is not yet known. It is also unknown if any other galaxy contains this kind of clusters, but it would be very unlikely that M31 is the sole galaxy with extended clusters. Another type of cluster are faint fuzzies which so far have only been found in lenticular galaxies like NGC 1023 and NGC 3384. They are characterized by their large size compared to globular clusters and a ringlike distribution around the centres of their host galaxies. As the latter they seem to be old objects. Astronomical significance Star clusters are important in many areas of astronomy. The reason behind this is that almost all the stars in old clusters were born at roughly the same time. Various properties of all the stars in a cluster are a function only of mass, and so stellar evolution theories rely on observations of open and globular clusters. This is primarily true for old globular clusters. In the case of young (age < 1Gyr) and intermediate-age (1 < age < 5 Gyr), factors such as age, mass, chemical compositions may also play vital roles. Based on their ages, star clusters can reveal a lot of information about their host galaxies. For example, star clusters residing in the Magellanic Clouds can provide essential information about the formation of the Magellanic Clouds dwarf galaxies. This, in turn, can help us understand many astrophysical processes happening in our own Milky Way Galaxy. These clusters, especially the young ones can explain the star formation process that might have happened in our Milky Way Galaxy. Clusters are also a crucial step in determining the distance scale of the universe. A few of the nearest clusters are close enough for their distances to be measured using parallax. A Hertzsprung–Russell diagram can be plotted for these clusters which has absolute values known on the luminosity axis. Then, when similar diagram is plotted for a cluster whose distance is not known, the position of the main sequence can be compared to that of the first cluster and the distance estimated. This process is known as main-sequence fitting. Reddening and stellar populations must be accounted for when using this method. Nearly all stars in the Galactic field, including the Sun, were initially born in regions with embedded clusters that disintegrated. This means that properties of stars and planetary systems may have been affected by early clustered environments. This appears to be the case for our own Solar System, in which chemical abundances point to the effects of a supernova from a nearby star early in our Solar System's history. Star cloud Technically not star clusters, star clouds are large groups of many stars within a galaxy, spread over very many light-years of space. Often they contain star clusters within them. The stars appear closely packed, but are not usually part of any structure. Within the Milky Way, star clouds show through gaps between dust clouds of the Great Rift, allowing deeper views along our particular line of sight. Star clouds have also been identified in other nearby galaxies. Examples of star clouds include the Large Sagittarius Star Cloud, Small Sagittarius Star Cloud, Scutum Star Cloud, Cygnus Star Cloud, Norma Star Cloud, and NGC 206 in the Andromeda Galaxy. Nomenclature In 1979, the International Astronomical Union's 17th general assembly recommended that newly discovered star clusters, open or globular, within the Galaxy have designations following the convention "Chhmm±ddd", always beginning with the prefix C, where h, m, and d represent the approximate coordinates of the cluster centre in hours and minutes of right ascension, and degrees of declination, respectively, with leading zeros. The designation, once assigned, is not to change, even if subsequent measurements improve on the location of the cluster centre. The first of such designations were assigned by Gosta Lynga in 1982. See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Pyroxene] | [TOKENS: 1494] |
Contents Pyroxene The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula XY(Si,Al)2O6, where X represents ions of calcium (Ca), sodium (Na), iron (Fe(II)) or magnesium (Mg) and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium (Cr), aluminium (Al), magnesium (Mg), cobalt (Co), manganese (Mn), scandium (Sc), titanium (Ti), vanadium (V) or even iron (Fe(II) or Fe(III)). Although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a common structure consisting of single chains of silica tetrahedra. Pyroxenes that crystallize in the monoclinic system are known as clinopyroxenes and those that crystallize in the orthorhombic system are known as orthopyroxenes. The name pyroxene is derived from the Ancient Greek words for 'fire' (πυρ, pur) and 'stranger' (ξένος, xénos). Pyroxenes were so named due to their presence in volcanic lavas, where they are sometimes found as crystals embedded in volcanic glass; it was assumed they were impurities in the glass, hence the name meaning "fire stranger". However, they are simply early-forming minerals that crystallized before the lava erupted. The upper mantle of Earth is composed mainly of olivine and pyroxene minerals. Pyroxene and feldspar are the major minerals in basalt, andesite, and gabbro rocks. Structure Pyroxenes are the most common single-chain silicate minerals (the only other important group of single-chain silicates, the pyroxenoids, are much less common.) Their structure consists of parallel chains of negatively-charged silica tetrahedra bonded together by metal cations. In other words, each silicon ion in a pyroxene crystal is surrounded by four oxygen ions forming a tetrahedron around the relatively small silicon ion. Each silicon ion shares two oxygen ions with neighboring silicon ions in the chain. The tetrahedra in the chain all face in the same direction, so that two oxygen ions are located on one face of the chain for every oxygen ion on the other face of the chain. The oxygen ions on the narrower face are described as apical oxygen ions. Pairs of chains are bound together on their apical sides by Y cations, with each Y cation surrounded by six oxygen ions. The resulting pairs of single chains have sometimes been likened to I-beams. The I-beams interlock, with additional X cations bonding the outer faces of the I-beams to neighboring I-beams and providing the remaining charge balance. This binding is relatively weak and gives pyroxenes their characteristic cleavage. Chemistry and nomenclature The chain silicate structure of the pyroxenes offers much flexibility in the incorporation of various cations and the names of the pyroxene minerals are primarily defined by their chemical composition. Pyroxene minerals are named according to the chemical species occupying the X (or M2) site, the Y (or M1) site, and the tetrahedral T site. Cations in Y (M1) site are closely bound to 6 oxygens in octahedral coordination. Cations in the X (M2) site can be coordinated with 6 to 8 oxygen atoms, depending on the cation size. As of 1989[update], twenty mineral names are recognised by the International Mineralogical Association's Commission on New Minerals and Mineral Names and 105 previously used names have been discarded. A typical pyroxene has mostly silicon in the tetrahedral site and predominantly ions with a charge of +2 in both the X and Y sites, giving the approximate formula XYT2O6. The names of the common calcium–iron–magnesium pyroxenes are defined in the 'pyroxene quadrilateral'. The enstatite-ferrosilite series ([Mg,Fe]SiO3) includes the common rock-forming mineral hypersthene, contains up to 5 mol.% calcium and exists in three polymorphs, orthorhombic orthoenstatite and protoenstatite and monoclinic clinoenstatite (and the ferrosilite equivalents). Increasing the calcium content prevents the formation of the orthorhombic phases and pigeonite ([Mg,Fe,Ca][Mg,Fe]Si2O6) only crystallises in the monoclinic system. There is no complete solid solution in calcium content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol.% are not stable with respect to a pair of exolved crystals. This leads to a miscibility gap between pigeonite and augite compositions. There is an arbitrary separation between augite and the diopside-hedenbergite (CaMgSi2O6−CaFeSi2O6) solid solution. The divide is taken at > 45 mol.% Ca. As the calcium ion cannot occupy the Y site, pyroxene with more than 50 mol.% calcium is not possible. A related mineral, wollastonite (CaSiO3), has the formula of the hypothetical calcium end member (Ca2Si2O6), but important structural differences mean that it is instead classified as a pyroxenoid. Magnesium, calcium and iron are by no means the only cations that can occupy the X and Y sites in the pyroxene structure. A second important series of pyroxene minerals is the sodium-rich pyroxenes, corresponding to the 'pyroxene triangle' nomenclature. The inclusion of sodium, which has a charge of 1+, into the pyroxene implies the need for a mechanism to make up the "missing" positive charge. In jadeite and aegirine, this is added by the inclusion of a 3+ cation (aluminium and iron(III), respectively) on the Y site. Sodium pyroxenes with more than 20 mol.% calcium, magnesium or iron(II) components are known as omphacite and aegirine-augite. With 80% or more of these components, the pyroxene is classified using the quadrilateral diagram. A wide range of other cations can be accommodated in the different sites of pyroxene structures. In assigning ions to sites, the basic rule is to work from left to right in this table, first assigning all silicon to the T site and then filling the site with the remaining aluminium and finally iron(III); extra aluminium or iron can be accommodated in the Y site and bulkier ions on the X site. Not all the resulting mechanisms to achieve charge neutrality follow the sodium example above, and there are several alternative schemes: In nature, more than one substitution may be found in the same mineral. Pyroxene minerals See also References External links |
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[SOURCE: https://en.wikipedia.org/wiki/Visual_gag] | [TOKENS: 506] |
Contents Visual gag In comedy, a visual gag or sight gag is anything which conveys its humour visually, often without words being used at all. The gag may involve a physical impossibility or an unexpected occurrence. The humor is caused by alternative interpretations of the goings-on. Visual gags are used in magic, plays, and acting on television or movies. Types In a 1991 essay Notes on the Sight Gag, Noel Carroll establishes a taxonomy of sight gags, breaking down the varieties into six types: History There are numerous examples in cinema history of directors who based most of the humor in their films on visual gags, even to the point of using no or minimal dialogue. Visual gags began in live theater. The first known use of a visual gag in a film was in the Lumière brothers' 1895 short, L'Arroseur Arrosé ("The Waterer Watered"), in which a gardener watering his plants becomes the subject of a boy's prank. An early pioneer in visual gags was Georges Méliès. The filmmaker experimented with techniques in the then-new film media creating techniques to trick viewers. Vaudeville actors often used gags in their routines. A classic vaudeville visual gag was for two actors to mirror each other's actions around a prop. Visual gags were continued into silent films and are considered a hallmark of the genre. In silent films, the actors in the mirror bit performed in silence with no music playing. Comedians including Charlie Chaplin, Buster Keaton, Harold Lloyd and the Marx Brothers often used visual humour because the technology used to record voices in film (and play it back in a synchronized presentation) did not yet exist. Often the differences between people are part of the comic duos, especially thin and fat actors are used such as Abbott and Costello and Laurel and Hardy. The New York Times cites the fourth Gilligan's Island episode, "Goodnight, Sweet Skipper", as a classic American sight gag. The castaways were trying to contact civilization with a radio. In the episode, Skipper can recall only how he converted the radio into a transmitter in World War II when he was sleepwalking. After Skipper was unsuccessful, Gilligan got it to work by pounding on the radio; he used it to briefly contact a pilot flying overhead. Gilligan retrieved Skipper and demonstrated how he pounded on the radio, causing the guts of the radio to fall out. Their rescue was foiled. See also References |
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[SOURCE: https://en.wikipedia.org/wiki/Lithe_(programming_language)] | [TOKENS: 420] |
Contents Lithe Lithe is an experimental programming language created in 1982 by David Sandberg at the University of Washington which allows the programmer to freely choose their own syntax. Lithe combines the ideas of syntax-directed translation and classes in a novel manner that results in a remarkably simple yet powerful language. Overview The standard class-based programming model does not specify a mechanism by which to manipulate objects: where Smalltalk uses message passing, Lithe uses syntax-directed translation (SDT). SDT is a method of translating a string into a sequence of actions by attaching one such action to each rule of a grammar. Thus, parsing a string of the grammar produces a sequence of rule applications. Lithe merges SDT with the class model by using classes as the non-terminal alphabet of the grammar. Since the grammar class used by Lithe properly contains all context-free grammars, a wide variety of syntax can be described, and SDT provides a simple way to attach semantics to any such syntax. The package is the unit of program modularity in Lithe. A package is divided into two parts: one that defines classes and another that defines rules. Information hiding is achieved by requiring both export keywords on those rules and classes that are to be seen outside a package and that the source package names be included in the with clause of the consumer package. Examples Programming in Lithe consists of defining rule-action pairs and classes. Take the task of computing the absolute value of a number, for example: After this rule-action pair has been defined, it can be freely used within Lithe source code, for example, the following expression will thereafter be valid: The equivalent rule in BNF would be: Note that the Lithe description swaps the left and right sides of the BNF one, then adds a name to each nonterminal in the BNF right-hand side. These names are used in the action part, which is expressed as a string that is translated into a sequence of actions by using other, previously defined, rule-action pairs (eventually, some of those rule-action pairs will invoke primitive actions). External links |
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[SOURCE: https://en.wikipedia.org/wiki/Israel_Border_Police] | [TOKENS: 2129] |
Contents Israel Border Police The Israel Border Police (Hebrew: מִשְׁמַר הַגְּבוּל, romanized: Mišmar Ha-Gvul) is the gendarmerie and border security branch of the Israel Police. It is also commonly known by its Hebrew abbreviation Magav (מג"ב), meaning border guard; its members are colloquially known as magavnikim (מג"בניקים; singular magavnik). "Border Guard" is often used as the official name of the Israel Border Police in English. While its main task is securing Israel's borders, it has also been deployed to assist the Israel Defense Forces, and for counter-terrorism and law enforcement operations in the Israeli-occupied West Bank and in Jerusalem. The Israeli Border Police is known to include many soldiers from minority backgrounds, being a particularly popular choice for Druze recruits, and also including many soldiers from Circassian, Arab Christian, and Bedouin backgrounds. History The Border Police was founded in 1949 as the Frontier Corps (חיל הספר, Heil HaSfar), a gendarmerie under the IDF with the task of providing security in rural areas and along the borders. Over the following years, it was gradually transferred to the command of the Police and became the Border Police. During these years, it secured new settlements and countered infiltration of Palestinian fedayeen, especially from Egypt and Jordan. During the 1956 Suez War, the Border Police was involved in the Kafr Qasim massacre. On the second day of the war, a curfew was imposed on the Israeli Arab village. Villagers who had worked in the village fields and were apparently unaware of the curfew were shot as they returned to the village, resulting in 49 dead. This event was strongly protested by the Israeli public and resulted in a landmark Supreme Court ruling on the obligation of soldiers to disobey manifestly illegal orders. During the 1967 Six-Day War, the Border Police fought alongside the IDF. After the war, it was deployed in the West Bank and Gaza Strip and charged with maintaining law and order as part of the military administration of Israeli-occupied territories. Since then, a significant portion of the Border Police's activity has been in these territories, especially during the years of the First Intifada and the Second (al-Aqsa) Intifada. In 1974, the counter-terror unit Yamam was established. In the 2000 October Riots, the Border Police was used as the main branch of the treatment in the events. During the Second Intifada, the Border Police took a large part in the security activity. In 2005, the Border Police participated in the implementation of the Israeli disengagement from Gaza. The Border Police's heaviest area of operation is Jerusalem. Virtually all "soldiers" seen patrolling Jerusalem's streets are Border Guard Police officers. Approximately 20% of all Border Guard personnel in the country are in Jerusalem. Jerusalem MAGAV also provides security and conducts military operations, raids, and arrests on Palestinians in cities like Jenin, Nablus, Jericho, Qalqilya, Tulkarm, Ramallah, and Hebron. In 2023, the National Guard of Israel was formed and attached to the Israel Border Police. The number of Border Guards is believed to be about 6,000 soldiers and officers. Structure The Border Police is composed of professional officers on payroll and field policemen redirected from the IDF (at age 18, Israelis can choose to serve in the Border Police instead of the IDF). All border policemen are trained in combat, counter-terrorism, riot control, and police work. Outstanding officers can train as specialists, such as snipers, buggy-drivers, dog operators, or bomb squad members. Because of their combat training, border police are employed in areas with greater risk of riots, violence and terror. They serve mainly in the countryside, in Arab villages and towns (along with the regular police), near the borders and in the West Bank. The Border Police is also responsible for security of rural settlements inside Israel with its Rural Police (Hebrew: שיטור כפרי, shitur kafri) units and Community Security Coordinators (Hebrew: רב"ש, rabash). Rural policemen are full-time professional officers and security coordinators are a mixture of full-time and volunteer officers. The Border Police has four Special forces units: The Yamam (Hebrew: ימ"מ, an acronym for Centralized Special Unit יחידה מרכזית מיוחדת, Yeḥida Merkazit Meyuḥedet), also called in Hebrew היחידה המיוחדת ללוחמה בטרור and Israel's National Counter Terror Unit (I.N.C.T.U.) in English, is Israel's national counter-terrorism unit. The Yamam is capable of both hostage-rescue operations and offensive takeover raids against terrorist targets in civilian areas. Besides military and counter-terrorism duties, it also performs SWAT duties and undercover police work. The unit operates snipers, police dog (K9) handlers, rappelling teams, EOD experts, paramedics, and undercover operators. YAMAM was formed in 1974 as a response to a wave of Palestinian terrorism. The unit has since carried out thousands of operations, killed hundreds of terrorists, and foiled countless terror attacks. It was awarded five citations of recommendation (Hebrew: צל"ש) from the Police Commissioner and one from the IDF Chief of general staff (Hebrew: צל"ש הרמטכ"ל). The Yamas is the undercover counter-terror unit. The Yamas is often expected to carry out complex missions with little or no preparation, often involving daylight raids in volatile areas. It does not follow regular military or police command structure and answers directly to the Shabak. The IDF long denied its existence. Volunteer Border Guard The Border Guard also deploys many volunteers. These members serve in regular Border Guard units. The Border Guard relies on volunteer soldiers to reinforce its manpower and help maintain Israel's security needs. The volunteer Border Guard are given special attention in sensitive places like Jerusalem where security threats are highest and sometimes double or even triple the manpower of full-time security forces in a given area. Many of these special Border Guard volunteers are Jewish immigrants who immigrated to Israel from places like the United States, United Kingdom, Canada, Australia, Italy, France, Germany, South Africa, South America, and the former Soviet Union. Volunteer Border Guard members leave behind jobs and families on a regular basis to serve in this combat unit. Some come from cities like Beit Shemesh, Ofrah, Ashkelon, Ra'anana and Haifa. They are not paid for serving in the Border Guard and serve in their spare time. Commanders Below is a list of current and former Border Police commanders. Ranks Border Police ranks are the same as those of the Israel Police and are similarly sworn in: the ranks of police officers and junior officers on the shirt collar, ranks of officers and senior officers on the cover. But in field uniforms, Border Police officers wear rank insignia on a green background worn on epaulets on top of both shoulders or on green epaulets. Border Police branch insignia is worn on the cap or beret. Enlisted grades wear rank insignia on the sleeve, halfway between the shoulder and the elbow. The Border Police British Army style insignia are white with blue interwoven threads backed with the appropriate corps color. Uniforms The Border has several types of uniforms: The first two resemble each other but the Madei Alef is made of higher quality materials in grey while the madei bet is in grey drab. The service uniform for all Border Police personnel is grey. The uniforms consist of a two-pocket shirt, plain or combat trousers, sweater, jacket or blouse, and shoes or boots. The grey fatigues are the same for winter and summer and heavy winter gear is issued as needed. Women's dress parallels the men's but may substitute a skirt for the trousers. Headgear included a service cap for dress and semi-dress and a field cap or bush hat worn with fatigues. Border Police personnel generally wear green berets in lieu of the service cap. Some units have small variations in their uniforms such as certain Security and Tactical units in Jerusalem who wear the standard IDF olive fatigues. Weapons and equipment The primary Border Police weapons are the CAR-15 and M-16 rifles, some of which are attached to the M-203 grenade launcher. The Border Police also use standard IDF equipment such as vests and helmets. Special units of Border Police use Glock 17, Glock 19, Jericho, or FN HP pistols. Some units, such as the Jerusalem Patrol Unit, carry the Beretta M9-22LR .22LR pistol. Special units use a variety of other weapons, Ruger S22s, sniper rifles, submachine guns, and shotguns. The Border Police extensively use riot dispersal means such as batons and shields, tear gas canisters, stun grenades, rubber bullets, and water cannons. Transportation The Border Police use Toyota Hilux, Carkal, Dawid wheeled armored personnel carriers and a variety of patrol cars and vehicles. Several units use motorcycles and ATVs. Memorial The Border Police Memorial and Heritage Center is in the western Carmel mountains near Zomet Iron at road 65. Criticism In 2001, the Israeli NGO B'tselem reported that violence against Palestinians in the occupied territories was widespread among Border Police units. Several cases of abuse, including the breaking of the hand of a three-year-old child, were documented over a short period of months. It added that prosecution of officers who perpetrate such acts was difficult, since Border Police, in contravention of the law, do not carry tags allowing them to be identified, and registering complaints against them was hindered by numerous bureaucratic obstacles, such as making travel permits to Israeli courts difficult to obtain. See also Notes References Bibliography External links |
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[SOURCE: https://en.wikipedia.org/wiki/Computer#cite_note-66] | [TOKENS: 10628] |
Contents Computer A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations (computation). Modern digital electronic computers can perform generic sets of operations known as programs, which enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the hardware, operating system, software, and peripheral equipment needed and used for full operation, or to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of industrial and consumer products use computers as control systems, including simple special-purpose devices like microwave ovens and remote controls, and factory devices like industrial robots. Computers are at the core of general-purpose devices such as personal computers and mobile devices such as smartphones. Computers power the Internet, which links billions of computers and users. Early computers were meant to be used only for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the Industrial Revolution, some mechanical devices were built to automate long, tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II, both electromechanical and using thermionic valves. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power, and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace (Moore's law noted that counts doubled every two years), leading to the Digital Revolution during the late 20th and early 21st centuries. Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, together with some type of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joysticks, etc.), output devices (monitors, printers, etc.), and input/output devices that perform both functions (e.g. touchscreens). Peripheral devices allow information to be retrieved from an external source, and they enable the results of operations to be saved and retrieved. Etymology It was not until the mid-20th century that the word acquired its modern definition; according to the Oxford English Dictionary, the first known use of the word computer was in a different sense, in a 1613 book called The Yong Mans Gleanings by the English writer Richard Brathwait: "I haue [sic] read the truest computer of Times, and the best Arithmetician that euer [sic] breathed, and he reduceth thy dayes into a short number." This usage of the term referred to a human computer, a person who carried out calculations or computations. The word continued to have the same meaning until the middle of the 20th century. During the latter part of this period, women were often hired as computers because they could be paid less than their male counterparts. By 1943, most human computers were women. The Online Etymology Dictionary gives the first attested use of computer in the 1640s, meaning 'one who calculates'; this is an "agent noun from compute (v.)". The Online Etymology Dictionary states that the use of the term to mean "'calculating machine' (of any type) is from 1897." The Online Etymology Dictionary indicates that the "modern use" of the term, to mean 'programmable digital electronic computer' dates from "1945 under this name; [in a] theoretical [sense] from 1937, as Turing machine". The name has remained, although modern computers are capable of many higher-level functions. History Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was most likely a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, likely livestock or grains, sealed in hollow unbaked clay containers.[a] The use of counting rods is one example. The abacus was initially used for arithmetic tasks. The Roman abacus was developed from devices used in Babylonia as early as 2400 BCE. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money. The Antikythera mechanism is believed to be the earliest known mechanical analog computer, according to Derek J. de Solla Price. It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to approximately c. 100 BCE. Devices of comparable complexity to the Antikythera mechanism would not reappear until the fourteenth century. Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī in the early 11th century. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BCE and is often attributed to Hipparchus. A combination of the planisphere and dioptra, the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235. Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe, an early fixed-wired knowledge processing machine with a gear train and gear-wheels, c. 1000 AD. The sector, a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation. The planimeter was a manual instrument to calculate the area of a closed figure by tracing over it with a mechanical linkage. The slide rule was invented around 1620–1630, by the English clergyman William Oughtred, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Slide rules with special scales are still used for quick performance of routine calculations, such as the E6B circular slide rule used for time and distance calculations on light aircraft. In the 1770s, Pierre Jaquet-Droz, a Swiss watchmaker, built a mechanical doll (automaton) that could write holding a quill pen. By switching the number and order of its internal wheels different letters, and hence different messages, could be produced. In effect, it could be mechanically "programmed" to read instructions. Along with two other complex machines, the doll is at the Musée d'Art et d'Histoire of Neuchâtel, Switzerland, and still operates. In 1831–1835, mathematician and engineer Giovanni Plana devised a Perpetual Calendar machine, which through a system of pulleys and cylinders could predict the perpetual calendar for every year from 0 CE (that is, 1 BCE) to 4000 CE, keeping track of leap years and varying day length. The tide-predicting machine invented by the Scottish scientist Sir William Thomson in 1872 was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location. The differential analyser, a mechanical analog computer designed to solve differential equations by integration, used wheel-and-disc mechanisms to perform the integration. In 1876, Sir William Thomson had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of the ball-and-disk integrators. In a differential analyzer, the output of one integrator drove the input of the next integrator, or a graphing output. The torque amplifier was the advance that allowed these machines to work. Starting in the 1920s, Vannevar Bush and others developed mechanical differential analyzers. In the 1890s, the Spanish engineer Leonardo Torres Quevedo began to develop a series of advanced analog machines that could solve real and complex roots of polynomials, which were published in 1901 by the Paris Academy of Sciences. Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the "father of the computer", he conceptualized and invented the first mechanical computer in the early 19th century. After working on his difference engine he announced his invention in 1822, in a paper to the Royal Astronomical Society, titled "Note on the application of machinery to the computation of astronomical and mathematical tables". He also designed to aid in navigational calculations, in 1833 he realized that a much more general design, an analytical engine, was possible. The input of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The engine would incorporate an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete. The machine was about a century ahead of its time. All the parts for his machine had to be made by hand – this was a major problem for a device with thousands of parts. Eventually, the project was dissolved with the decision of the British Government to cease funding. Babbage's failure to complete the analytical engine can be chiefly attributed to political and financial difficulties as well as his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow. Nevertheless, his son, Henry Babbage, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906. In his work Essays on Automatics published in 1914, Leonardo Torres Quevedo wrote a brief history of Babbage's efforts at constructing a mechanical Difference Engine and Analytical Engine. The paper contains a design of a machine capable to calculate formulas like a x ( y − z ) 2 {\displaystyle a^{x}(y-z)^{2}} , for a sequence of sets of values. The whole machine was to be controlled by a read-only program, which was complete with provisions for conditional branching. He also introduced the idea of floating-point arithmetic. In 1920, to celebrate the 100th anniversary of the invention of the arithmometer, Torres presented in Paris the Electromechanical Arithmometer, which allowed a user to input arithmetic problems through a keyboard, and computed and printed the results, demonstrating the feasibility of an electromechanical analytical engine. During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers. The first modern analog computer was a tide-predicting machine, invented by Sir William Thomson (later to become Lord Kelvin) in 1872. The differential analyser, a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in 1876 by James Thomson, the elder brother of the more famous Sir William Thomson. The art of mechanical analog computing reached its zenith with the differential analyzer, completed in 1931 by Vannevar Bush at MIT. By the 1950s, the success of digital electronic computers had spelled the end for most analog computing machines, but analog computers remained in use during the 1950s in some specialized applications such as education (slide rule) and aircraft (control systems).[citation needed] Claude Shannon's 1937 master's thesis laid the foundations of digital computing, with his insight of applying Boolean algebra to the analysis and synthesis of switching circuits being the basic concept which underlies all electronic digital computers. By 1938, the United States Navy had developed the Torpedo Data Computer, an electromechanical analog computer for submarines that used trigonometry to solve the problem of firing a torpedo at a moving target. During World War II, similar devices were developed in other countries. Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation. These devices had a low operating speed and were eventually superseded by much faster all-electric computers, originally using vacuum tubes. The Z2, created by German engineer Konrad Zuse in 1939 in Berlin, was one of the earliest examples of an electromechanical relay computer. In 1941, Zuse followed his earlier machine up with the Z3, the world's first working electromechanical programmable, fully automatic digital computer. The Z3 was built with 2000 relays, implementing a 22-bit word length that operated at a clock frequency of about 5–10 Hz. Program code was supplied on punched film while data could be stored in 64 words of memory or supplied from the keyboard. It was quite similar to modern machines in some respects, pioneering numerous advances such as floating-point numbers. Rather than the harder-to-implement decimal system (used in Charles Babbage's earlier design), using a binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time. The Z3 was not itself a universal computer but could be extended to be Turing complete. Zuse's next computer, the Z4, became the world's first commercial computer; after initial delay due to the Second World War, it was completed in 1950 and delivered to the ETH Zurich. The computer was manufactured by Zuse's own company, Zuse KG, which was founded in 1941 as the first company with the sole purpose of developing computers in Berlin. The Z4 served as the inspiration for the construction of the ERMETH, the first Swiss computer and one of the first in Europe. Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. The engineer Tommy Flowers, working at the Post Office Research Station in London in the 1930s, began to explore the possible use of electronics for the telephone exchange. Experimental equipment that he built in 1934 went into operation five years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes. In the US, John Vincent Atanasoff and Clifford E. Berry of Iowa State University developed and tested the Atanasoff–Berry Computer (ABC) in 1942, the first "automatic electronic digital computer". This design was also all-electronic and used about 300 vacuum tubes, with capacitors fixed in a mechanically rotating drum for memory. During World War II, the British code-breakers at Bletchley Park achieved a number of successes at breaking encrypted German military communications. The German encryption machine, Enigma, was first attacked with the help of the electro-mechanical bombes which were often run by women. To crack the more sophisticated German Lorenz SZ 40/42 machine, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to build the Colossus. He spent eleven months from early February 1943 designing and building the first Colossus. After a functional test in December 1943, Colossus was shipped to Bletchley Park, where it was delivered on 18 January 1944 and attacked its first message on 5 February. Colossus was the world's first electronic digital programmable computer. It used a large number of valves (vacuum tubes). It had paper-tape input and was capable of being configured to perform a variety of boolean logical operations on its data, but it was not Turing-complete. Nine Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines in total). Colossus Mark I contained 1,500 thermionic valves (tubes), but Mark II with 2,400 valves, was both five times faster and simpler to operate than Mark I, greatly speeding the decoding process. The ENIAC (Electronic Numerical Integrator and Computer) was the first electronic programmable computer built in the U.S. Although the ENIAC was similar to the Colossus, it was much faster, more flexible, and it was Turing-complete. Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches. The programmers of the ENIAC were six women, often known collectively as the "ENIAC girls". It combined the high speed of electronics with the ability to be programmed for many complex problems. It could add or subtract 5000 times a second, a thousand times faster than any other machine. It also had modules to multiply, divide, and square root. High speed memory was limited to 20 words (about 80 bytes). Built under the direction of John Mauchly and J. Presper Eckert at the University of Pennsylvania, ENIAC's development and construction lasted from 1943 to full operation at the end of 1945. The machine was huge, weighing 30 tons, using 200 kilowatts of electric power and contained over 18,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors. The principle of the modern computer was proposed by Alan Turing in his seminal 1936 paper, On Computable Numbers. Turing proposed a simple device that he called "Universal Computing machine" and that is now known as a universal Turing machine. He proved that such a machine is capable of computing anything that is computable by executing instructions (program) stored on tape, allowing the machine to be programmable. The fundamental concept of Turing's design is the stored program, where all the instructions for computing are stored in memory. Von Neumann acknowledged that the central concept of the modern computer was due to this paper. Turing machines are to this day a central object of study in theory of computation. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete, which is to say, they have algorithm execution capability equivalent to a universal Turing machine. Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring of the machine. With the proposal of the stored-program computer this changed. A stored-program computer includes by design an instruction set and can store in memory a set of instructions (a program) that details the computation. The theoretical basis for the stored-program computer was laid out by Alan Turing in his 1936 paper. In 1945, Turing joined the National Physical Laboratory and began work on developing an electronic stored-program digital computer. His 1945 report "Proposed Electronic Calculator" was the first specification for such a device. John von Neumann at the University of Pennsylvania also circulated his First Draft of a Report on the EDVAC in 1945. The Manchester Baby was the world's first stored-program computer. It was built at the University of Manchester in England by Frederic C. Williams, Tom Kilburn and Geoff Tootill, and ran its first program on 21 June 1948. It was designed as a testbed for the Williams tube, the first random-access digital storage device. Although the computer was described as "small and primitive" by a 1998 retrospective, it was the first working machine to contain all of the elements essential to a modern electronic computer. As soon as the Baby had demonstrated the feasibility of its design, a project began at the university to develop it into a practically useful computer, the Manchester Mark 1. The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1, the world's first commercially available general-purpose computer. Built by Ferranti, it was delivered to the University of Manchester in February 1951. At least seven of these later machines were delivered between 1953 and 1957, one of them to Shell labs in Amsterdam. In October 1947 the directors of British catering company J. Lyons & Company decided to take an active role in promoting the commercial development of computers. Lyons's LEO I computer, modelled closely on the Cambridge EDSAC of 1949, became operational in April 1951 and ran the world's first routine office computer job. The concept of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. John Bardeen and Walter Brattain, while working under William Shockley at Bell Labs, built the first working transistor, the point-contact transistor, in 1947, which was followed by Shockley's bipolar junction transistor in 1948. From 1955 onwards, transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Junction transistors were much more reliable than vacuum tubes and had longer, indefinite, service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space. However, early junction transistors were relatively bulky devices that were difficult to manufacture on a mass-production basis, which limited them to a number of specialized applications. At the University of Manchester, a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves. Their first transistorized computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955. However, the machine did make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer. That distinction goes to the Harwell CADET of 1955, built by the electronics division of the Atomic Energy Research Establishment at Harwell. The metal–oxide–silicon field-effect transistor (MOSFET), also known as the MOS transistor, was invented at Bell Labs between 1955 and 1960 and was the first truly compact transistor that could be miniaturized and mass-produced for a wide range of uses. With its high scalability, and much lower power consumption and higher density than bipolar junction transistors, the MOSFET made it possible to build high-density integrated circuits. In addition to data processing, it also enabled the practical use of MOS transistors as memory cell storage elements, leading to the development of MOS semiconductor memory, which replaced earlier magnetic-core memory in computers. The MOSFET led to the microcomputer revolution, and became the driving force behind the computer revolution. The MOSFET is the most widely used transistor in computers, and is the fundamental building block of digital electronics. The next great advance in computing power came with the advent of the integrated circuit (IC). The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence, Geoffrey W.A. Dummer. Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Quality Electronic Components in Washington, D.C., on 7 May 1952. The first working ICs were invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor. Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working integrated example on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material ... wherein all the components of the electronic circuit are completely integrated". However, Kilby's invention was a hybrid integrated circuit (hybrid IC), rather than a monolithic integrated circuit (IC) chip. Kilby's IC had external wire connections, which made it difficult to mass-produce. Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. Noyce's invention was the first true monolithic IC chip. His chip solved many practical problems that Kilby's had not. Produced at Fairchild Semiconductor, it was made of silicon, whereas Kilby's chip was made of germanium. Noyce's monolithic IC was fabricated using the planar process, developed by his colleague Jean Hoerni in early 1959. In turn, the planar process was based on Carl Frosch and Lincoln Derick work on semiconductor surface passivation by silicon dioxide. Modern monolithic ICs are predominantly MOS (metal–oxide–semiconductor) integrated circuits, built from MOSFETs (MOS transistors). The earliest experimental MOS IC to be fabricated was a 16-transistor chip built by Fred Heiman and Steven Hofstein at RCA in 1962. General Microelectronics later introduced the first commercial MOS IC in 1964, developed by Robert Norman. Following the development of the self-aligned gate (silicon-gate) MOS transistor by Robert Kerwin, Donald Klein and John Sarace at Bell Labs in 1967, the first silicon-gate MOS IC with self-aligned gates was developed by Federico Faggin at Fairchild Semiconductor in 1968. The MOSFET has since become the most critical device component in modern ICs. The development of the MOS integrated circuit led to the invention of the microprocessor, and heralded an explosion in the commercial and personal use of computers. While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single-chip microprocessor was the Intel 4004, designed and realized by Federico Faggin with his silicon-gate MOS IC technology, along with Ted Hoff, Masatoshi Shima and Stanley Mazor at Intel.[b] In the early 1970s, MOS IC technology enabled the integration of more than 10,000 transistors on a single chip. System on a Chip (SoCs) are complete computers on a microchip (or chip) the size of a coin. They may or may not have integrated RAM and flash memory. If not integrated, the RAM is usually placed directly above (known as Package on package) or below (on the opposite side of the circuit board) the SoC, and the flash memory is usually placed right next to the SoC. This is done to improve data transfer speeds, as the data signals do not have to travel long distances. Since ENIAC in 1945, computers have advanced enormously, with modern SoCs (such as the Snapdragon 865) being the size of a coin while also being hundreds of thousands of times more powerful than ENIAC, integrating billions of transistors, and consuming only a few watts of power. The first mobile computers were heavy and ran from mains power. The 50 lb (23 kg) IBM 5100 was an early example. Later portables such as the Osborne 1 and Compaq Portable were considerably lighter but still needed to be plugged in. The first laptops, such as the Grid Compass, removed this requirement by incorporating batteries – and with the continued miniaturization of computing resources and advancements in portable battery life, portable computers grew in popularity in the 2000s. The same developments allowed manufacturers to integrate computing resources into cellular mobile phones by the early 2000s. These smartphones and tablets run on a variety of operating systems and recently became the dominant computing device on the market. These are powered by System on a Chip (SoCs), which are complete computers on a microchip the size of a coin. Types Computers can be classified in a number of different ways, including: A computer does not need to be electronic, nor even have a processor, nor RAM, nor even a hard disk. While popular usage of the word "computer" is synonymous with a personal electronic computer,[c] a typical modern definition of a computer is: "A device that computes, especially a programmable [usually] electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information." According to this definition, any device that processes information qualifies as a computer. Hardware The term hardware covers all of those parts of a computer that are tangible physical objects. Circuits, computer chips, graphic cards, sound cards, memory (RAM), motherboard, displays, power supplies, cables, keyboards, printers and "mice" input devices are all hardware. A general-purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by buses, often made of groups of wires. Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a "1", and when off it represents a "0" (in positive logic representation). The circuits are arranged in logic gates so that one or more of the circuits may control the state of one or more of the other circuits. Input devices are the means by which the operations of a computer are controlled and it is provided with data. Examples include: Output devices are the means by which a computer provides the results of its calculations in a human-accessible form. Examples include: The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into control signals that activate other parts of the computer.[e] Control systems in advanced computers may change the order of execution of some instructions to improve performance. A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.[f] The control system's function is as follows— this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU: Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow). The sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program, and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer, which runs a microcode program that causes all of these events to happen. The control unit, ALU, and registers are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components. Since the 1970s, CPUs have typically been constructed on a single MOS integrated circuit chip called a microprocessor. The ALU is capable of performing two classes of operations: arithmetic and logic. The set of arithmetic operations that a particular ALU supports may be limited to addition and subtraction, or might include multiplication, division, trigonometry functions such as sine, cosine, etc., and square roots. Some can operate only on whole numbers (integers) while others use floating point to represent real numbers, albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return Boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?"). Logic operations involve Boolean logic: AND, OR, XOR, and NOT. These can be useful for creating complicated conditional statements and processing Boolean logic. Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously. Graphics processors and computers with SIMD and MIMD features often contain ALUs that can perform arithmetic on vectors and matrices. A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595." The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers. In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers (28 = 256); either from 0 to 255 or −128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory. The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed. Computer main memory comes in two principal varieties: RAM can be read and written to anytime the CPU commands it, but ROM is preloaded with data and software that never changes, therefore the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware, because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary.[g] In more sophisticated computers there may be one or more RAM cache memories, which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part. I/O is the means by which a computer exchanges information with the outside world. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O. I/O devices are often complex computers in their own right, with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics.[citation needed] Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O. A 2016-era flat screen display contains its own computer circuitry. While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by multitasking, i.e. having the computer switch rapidly between running each program in turn. One means by which this is done is with a special signal called an interrupt, which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time". Then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time, even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn. Before the era of inexpensive computers, the principal use for multitasking was to allow many people to share the same computer. Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly, in direct proportion to the number of programs it is running, but most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run simultaneously without unacceptable speed loss. Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed in only large and powerful machines such as supercomputers, mainframe computers and servers. Multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result. Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general-purpose computers.[h] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful for only specialized tasks due to the large scale of program organization required to use most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks. Software Software is the part of a computer system that consists of the encoded information that determines the computer's operation, such as data or instructions on how to process the data. In contrast to the physical hardware from which the system is built, software is immaterial. Software includes computer programs, libraries and related non-executable data, such as online documentation or digital media. It is often divided into system software and application software. Computer hardware and software require each other and neither is useful on its own. When software is stored in hardware that cannot easily be modified, such as with BIOS ROM in an IBM PC compatible computer, it is sometimes called "firmware". The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that some type of instructions (the program) can be given to the computer, and it will process them. Modern computers based on the von Neumann architecture often have machine code in the form of an imperative programming language. In practical terms, a computer program may be just a few instructions or extend to many millions of instructions, as do the programs for word processors and web browsers for example. A typical modern computer can execute billions of instructions per second (gigaflops) and rarely makes a mistake over many years of operation. Large computer programs consisting of several million instructions may take teams of programmers years to write, and due to the complexity of the task almost certainly contain errors. This section applies to most common RAM machine–based computers. In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to the instruction following that jump instruction. Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention. Comparatively, a person using a pocket calculator can perform a basic arithmetic operation such as adding two numbers with just a few button presses. But to add together all of the numbers from 1 to 1,000 would take thousands of button presses and a lot of time, with a near certainty of making a mistake. On the other hand, a computer may be programmed to do this with just a few simple instructions. The following example is written in the MIPS assembly language: Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in a fraction of a second. In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode; the command to multiply them would have a different opcode, and so on. The simplest computers are able to perform any of a handful of different instructions; the more complex computers have several hundred to choose from, each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of these instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer in the same way as numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches. While it is possible to write computer programs as long lists of numbers (machine language) and while this technique was used with many early computers,[i] it is extremely tedious and potentially error-prone to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember – a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler. A programming language is a notation system for writing the source code from which a computer program is produced. Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine code by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques. There are thousands of programming languages—some intended for general purpose programming, others useful for only highly specialized applications. Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) are generally unique to the particular architecture of a computer's central processing unit (CPU). For instance, an ARM architecture CPU (such as may be found in a smartphone or a hand-held videogame) cannot understand the machine language of an x86 CPU that might be in a PC.[j] Historically a significant number of other CPU architectures were created and saw extensive use, notably including the MOS Technology 6502 and 6510 in addition to the Zilog Z80. Although considerably easier than in machine language, writing long programs in assembly language is often difficult and is also error prone. Therefore, most practical programs are written in more abstract high-level programming languages that are able to express the needs of the programmer more conveniently (and thereby help reduce programmer error). High level languages are usually "compiled" into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler.[k] High level languages are less related to the workings of the target computer than assembly language, and more related to the language and structure of the problem(s) to be solved by the final program. It is therefore often possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles. Program design of small programs is relatively simple and involves the analysis of the problem, collection of inputs, using the programming constructs within languages, devising or using established procedures and algorithms, providing data for output devices and solutions to the problem as applicable. As problems become larger and more complex, features such as subprograms, modules, formal documentation, and new paradigms such as object-oriented programming are encountered. Large programs involving thousands of line of code and more require formal software methodologies. The task of developing large software systems presents a significant intellectual challenge. Producing software with an acceptably high reliability within a predictable schedule and budget has historically been difficult; the academic and professional discipline of software engineering concentrates specifically on this challenge. Errors in computer programs are called "bugs". They may be benign and not affect the usefulness of the program, or have only subtle effects. However, in some cases they may cause the program or the entire system to "hang", becoming unresponsive to input such as mouse clicks or keystrokes, to completely fail, or to crash. Otherwise benign bugs may sometimes be harnessed for malicious intent by an unscrupulous user writing an exploit, code designed to take advantage of a bug and disrupt a computer's proper execution. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design.[l] Admiral Grace Hopper, an American computer scientist and developer of the first compiler, is credited for having first used the term "bugs" in computing after a dead moth was found shorting a relay in the Harvard Mark II computer in September 1947. Networking and the Internet Computers have been used to coordinate information between multiple physical locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems such as Sabre. In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET. Logic gates are a common abstraction which can apply to most of the above digital or analog paradigms. The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a minimum capability (being Turing-complete) is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, any type of computer (netbook, supercomputer, cellular automaton, etc.) is able to perform the same computational tasks, given enough time and storage capacity. In the 20th century, artificial intelligence systems were predominantly symbolic: they executed code that was explicitly programmed by software developers. Machine learning models, however, have a set parameters that are adjusted throughout training, so that the model learns to accomplish a task based on the provided data. The efficiency of machine learning (and in particular of neural networks) has rapidly improved with progress in hardware for parallel computing, mainly graphics processing units (GPUs). Some large language models are able to control computers or robots. AI progress may lead to the creation of artificial general intelligence (AGI), a type of AI that could accomplish virtually any intellectual task at least as well as humans. Professions and organizations As the use of computers has spread throughout society, there are an increasing number of careers involving computers. The need for computers to work well together and to be able to exchange information has spawned the need for many standards organizations, clubs and societies of both a formal and informal nature. See also Notes References Sources External links |
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Contents Social network 1800s: Martineau · Tocqueville · Marx · Spencer · Le Bon · Ward · Pareto · Tönnies · Veblen · Simmel · Durkheim · Addams · Mead · Weber · Du Bois · Mannheim · Elias A social network is a social structure consisting of a set of social actors (such as individuals or organizations), networks of dyadic ties, and other social interactions between actors. The social network perspective provides a set of methods for analyzing the structure of whole social entities along with a variety of theories explaining the patterns observed in these structures. The study of these structures uses social network analysis to identify local and global patterns, locate influential entities, and examine dynamics of networks. For instance, social network analysis has been used in studying the spread of misinformation on social media platforms or analyzing the influence of key figures in social networks. Social networks and the analysis of them is an inherently interdisciplinary academic field which emerged from social psychology, sociology, statistics, and graph theory. Georg Simmel authored early structural theories in sociology emphasizing the dynamics of triads and "web of group affiliations". Jacob Moreno is credited with developing the first sociograms in the 1930s to study interpersonal relationships. These approaches were mathematically formalized in the 1950s and theories and methods of social networks became pervasive in the social and behavioral sciences by the 1980s. Social network analysis is now one of the major paradigms in contemporary sociology, and is also employed in a number of other social and formal sciences. Together with other complex networks, it forms part of the nascent field of network science. Overview The social network is a theoretical construct useful in the social sciences to study relationships between individuals, groups, organizations, or even entire societies (social units, see differentiation). The term is used to describe a social structure determined by such interactions. The ties through which any given social unit connects represent the convergence of the various social contacts of that unit. This theoretical approach is, necessarily, relational. An axiom of the social network approach to understanding social interaction is that social phenomena should be primarily conceived and investigated through the properties of relations between and within units, instead of the properties of these units themselves. Thus, one common criticism of social network theory is that individual agency is often ignored although this may not be the case in practice (see agent-based modeling). Precisely because many different types of relations, singular or in combination, form these network configurations, network analytics are useful to a broad range of research enterprises. In social science, these fields of study include, but are not limited to anthropology, biology, communication studies, economics, geography, information science, organizational studies, social psychology, sociology, and sociolinguistics. History In the late 1890s, both Émile Durkheim and Ferdinand Tönnies foreshadowed the idea of social networks in their theories and research of social groups. Tönnies argued that social groups can exist as personal and direct social ties that either link individuals who share values and belief (Gemeinschaft, German, commonly translated as "community") or impersonal, formal, and instrumental social links (Gesellschaft, German, commonly translated as "society"). Durkheim gave a non-individualistic explanation of social facts, arguing that social phenomena arise when interacting individuals constitute a reality that can no longer be accounted for in terms of the properties of individual actors. Georg Simmel, writing at the turn of the twentieth century, pointed to the nature of networks and the effect of network size on interaction and examined the likelihood of interaction in loosely knit networks rather than groups. Major developments in the field can be seen in the 1930s by several groups in psychology, anthropology, and mathematics working independently. In psychology, in the 1930s, Jacob L. Moreno began systematic recording and analysis of social interaction in small groups, especially classrooms and work groups (see sociometry). In anthropology, the foundation for social network theory is the theoretical and ethnographic work of Bronislaw Malinowski, Alfred Radcliffe-Brown, and Claude Lévi-Strauss. A group of social anthropologists associated with Max Gluckman and the Manchester School, including John A. Barnes, J. Clyde Mitchell and Elizabeth Bott Spillius, often are credited with performing some of the first fieldwork from which network analyses were performed, investigating community networks in southern Africa, India and the United Kingdom. Concomitantly, British anthropologist S. F. Nadel codified a theory of social structure that was influential in later network analysis. In sociology, the early (1930s) work of Talcott Parsons set the stage for taking a relational approach to understanding social structure. Later, drawing upon Parsons' theory, the work of sociologist Peter Blau provides a strong impetus for analyzing the relational ties of social units with his work on social exchange theory. By the 1970s, a growing number of scholars worked to combine the different tracks and traditions. One group consisted of sociologist Harrison White and his students at the Harvard University Department of Social Relations. Also independently active in the Harvard Social Relations department at the time were Charles Tilly, who focused on networks in political and community sociology and social movements, and Stanley Milgram, who developed the "six degrees of separation" thesis. Mark Granovetter and Barry Wellman are among the former students of White who elaborated and championed the analysis of social networks. Beginning in the late 1990s, social network analysis experienced work by sociologists, political scientists, and physicists such as Duncan J. Watts, Albert-László Barabási, Peter Bearman, Nicholas A. Christakis, James H. Fowler, and others, developing and applying new models and methods to emerging data available about online social networks, as well as "digital traces" regarding face-to-face networks. Levels of analysis In general, social networks are self-organizing, emergent, and complex, such that a globally coherent pattern appears from the local interaction of the elements that make up the system. These patterns become more apparent as network size increases. However, a global network analysis of, for example, all interpersonal relationships in the world is not feasible and is likely to contain so much information as to be uninformative. Practical limitations of computing power, ethics and participant recruitment and payment also limit the scope of a social network analysis. The nuances of a local system may be lost in a large network analysis, hence the quality of information may be more important than its scale for understanding network properties. Thus, social networks are analyzed at the scale relevant to the researcher's theoretical question. Although levels of analysis are not necessarily mutually exclusive, there are three general levels into which networks may fall: micro-level, meso-level, and macro-level. At the micro-level, social network research typically begins with an individual, snowballing as social relationships are traced, or may begin with a small group of individuals in a particular social context. Dyadic level: A dyad is a social relationship between two individuals. Network research on dyads may concentrate on structure of the relationship (e.g. multiplexity, strength), social equality, and tendencies toward reciprocity/mutuality. Triadic level: Add one individual to a dyad, and you have a triad. Research at this level may concentrate on factors such as balance and transitivity, as well as social equality and tendencies toward reciprocity/mutuality. In the balance theory of Fritz Heider the triad is the key to social dynamics. The discord in a rivalrous love triangle is an example of an unbalanced triad, likely to change to a balanced triad by a change in one of the relations. The dynamics of social friendships in society has been modeled by balancing triads. The study is carried forward with the theory of signed graphs. Actor level: The smallest unit of analysis in a social network is an individual in their social setting, i.e., an "actor" or "ego." Egonetwork analysis focuses on network characteristics, such as size, relationship strength, density, centrality, prestige and roles such as isolates, liaisons, and bridges. Such analyses, are most commonly used in the fields of psychology or social psychology, ethnographic kinship analysis or other genealogical studies of relationships between individuals. Subset level: Subset levels of network research problems begin at the micro-level, but may cross over into the meso-level of analysis. Subset level research may focus on distance and reachability, cliques, cohesive subgroups, or other group actions or behavior. In general, meso-level theories begin with a population size that falls between the micro- and macro-levels. However, meso-level may also refer to analyses that are specifically designed to reveal connections between micro- and macro-levels. Meso-level networks are low density and may exhibit causal processes distinct from interpersonal micro-level networks. Organizations: Formal organizations are social groups that distribute tasks for a collective goal. Network research on organizations may focus on either intra-organizational or inter-organizational ties in terms of formal or informal relationships. Intra-organizational networks themselves often contain multiple levels of analysis, especially in larger organizations with multiple branches, franchises or semi-autonomous departments. In these cases, research is often conducted at a work group level and organization level, focusing on the interplay between the two structures. Experiments with networked groups online have documented ways to optimize group-level coordination through diverse interventions, including the addition of autonomous agents to the groups. Randomly distributed networks: Exponential random graph models of social networks became state-of-the-art methods of social network analysis in the 1980s. This framework has the capacity to represent social-structural effects commonly observed in many human social networks, including general degree-based structural effects commonly observed in many human social networks as well as reciprocity and transitivity, and at the node-level, homophily and attribute-based activity and popularity effects, as derived from explicit hypotheses about dependencies among network ties. Parameters are given in terms of the prevalence of small subgraph configurations in the network and can be interpreted as describing the combinations of local social processes from which a given network emerges. These probability models for networks on a given set of actors allow generalization beyond the restrictive dyadic independence assumption of micro-networks, allowing models to be built from theoretical structural foundations of social behavior. Scale-free networks: A scale-free network is a network whose degree distribution follows a power law, at least asymptotically. In network theory a scale-free ideal network is a random network with a degree distribution that unravels the size distribution of social groups. Specific characteristics of scale-free networks vary with the theories and analytical tools used to create them, however, in general, scale-free networks have some common characteristics. One notable characteristic in a scale-free network is the relative commonness of vertices with a degree that greatly exceeds the average. The highest-degree nodes are often called "hubs", and may serve specific purposes in their networks, although this depends greatly on the social context. Another general characteristic of scale-free networks is the clustering coefficient distribution, which decreases as the node degree increases. This distribution also follows a power law. The Barabási model of network evolution shown above is an example of a scale-free network. Rather than tracing interpersonal interactions, macro-level analyses generally trace the outcomes of interactions, such as economic or other resource transfer interactions over a large population. Large-scale networks: Large-scale network is a term somewhat synonymous with "macro-level." It is primarily used in social and behavioral sciences, and in economics. Originally, the term was used extensively in the computer sciences (see large-scale network mapping). Complex networks: Most larger social networks display features of social complexity, which involves substantial non-trivial features of network topology, with patterns of complex connections between elements that are neither purely regular nor purely random (see, complexity science, dynamical system and chaos theory), as do biological, and technological networks. Such complex network features include a heavy tail in the degree distribution, a high clustering coefficient, assortativity or disassortativity among vertices, community structure (see stochastic block model), and hierarchical structure. In the case of agency-directed networks these features also include reciprocity, triad significance profile (TSP, see network motif), and other features. In contrast, many of the mathematical models of networks that have been studied in the past, such as lattices and random graphs, do not show these features. Theoretical links Various theoretical frameworks have been imported for the use of social network analysis. The most prominent of these are Graph theory, Balance theory, Social comparison theory, and more recently, the Social identity approach. Few complete theories have been produced from social network analysis. Two that have are structural role theory and heterophily theory. The basis of Heterophily Theory was the finding in one study that more numerous weak ties can be important in seeking information and innovation, as cliques have a tendency to have more homogeneous opinions as well as share many common traits. This homophilic tendency was the reason for the members of the cliques to be attracted together in the first place. However, being similar, each member of the clique would also know more or less what the other members knew. To find new information or insights, members of the clique will have to look beyond the clique to its other friends and acquaintances. This is what Granovetter called "the strength of weak ties". Structural holes In the context of networks, social capital exists where people have an advantage because of their location in a network. Contacts in a network provide information, opportunities and perspectives that can be beneficial to the central player in the network. Most social structures tend to be characterized by dense clusters of strong connections. Information within these clusters tends to be rather homogeneous and redundant. Non-redundant information is most often obtained through contacts in different clusters. When two separate clusters possess non-redundant information, there is said to be a structural hole between them. Thus, a network that bridges structural holes will provide network benefits that are in some degree additive, rather than overlapping. An ideal network structure has a vine and cluster structure, providing access to many different clusters and structural holes. Networks rich in structural holes are a form of social capital in that they offer information benefits. The main player in a network that bridges structural holes is able to access information from diverse sources and clusters. For example, in business networks, this is beneficial to an individual's career because he is more likely to hear of job openings and opportunities if his network spans a wide range of contacts in different industries/sectors. This concept is similar to Mark Granovetter's theory of weak ties, which rests on the basis that having a broad range of contacts is most effective for job attainment. Structural holes have been widely applied in social network analysis, resulting in applications in a wide range of practical scenarios as well as machine learning-based social prediction. Research clusters Research has used network analysis to examine networks created when artists are exhibited together in museum exhibition. Such networks have been shown to affect an artist's recognition in history and historical narratives, even when controlling for individual accomplishments of the artist. Other work examines how network grouping of artists can affect an individual artist's auction performance. An artist's status has been shown to increase when associated with higher status networks, though this association has diminishing returns over an artist's career. In J.A. Barnes' day, a "community" referred to a specific geographic location and studies of community ties had to do with who talked, associated, traded, and attended church with whom. Today, however, there are extended "online" communities developed through telecommunications devices and social network services. Such devices and services require extensive and ongoing maintenance and analysis, often using network science methods. Community development studies, today, also make extensive use of such methods. Complex networks require methods specific to modelling and interpreting social complexity and complex adaptive systems, including techniques of dynamic network analysis. Mechanisms such as Dual-phase evolution explain how temporal changes in connectivity contribute to the formation of structure in social networks. The study of social networks is being used to examine the nature of interdependencies between actors and the ways in which these are related to outcomes of conflict and cooperation. Areas of study include cooperative behavior among participants in collective actions such as protests; promotion of peaceful behavior, social norms, and public goods within communities through networks of informal governance; the role of social networks in both intrastate conflict and interstate conflict; and social networking among politicians, constituents, and bureaucrats. In criminology and urban sociology, much attention has been paid to the social networks among criminal actors. For example, murders can be seen as a series of exchanges between gangs. Murders can be seen to diffuse outwards from a single source, because weaker gangs cannot afford to kill members of stronger gangs in retaliation, but must commit other violent acts to maintain their reputation for strength. Diffusion of ideas and innovations studies focus on the spread and use of ideas from one actor to another or one culture and another. This line of research seeks to explain why some become "early adopters" of ideas and innovations, and links social network structure with facilitating or impeding the spread of an innovation. A case in point is the social diffusion of linguistic innovation such as neologisms. Experiments and large-scale field trials (e.g., by Nicholas Christakis and collaborators) have shown that cascades of desirable behaviors can be induced in social groups, in settings as diverse as Honduras villages, Indian slums, or in the lab. Still other experiments have documented the experimental induction of social contagion of voting behavior, emotions, risk perception, and commercial products. In demography, the study of social networks has led to new sampling methods for estimating and reaching populations that are hard to enumerate (for example, homeless people or intravenous drug users.) For example, respondent driven sampling is a network-based sampling technique that relies on respondents to a survey recommending further respondents. The field of sociology focuses almost entirely on networks of outcomes of social interactions. More narrowly, economic sociology considers behavioral interactions of individuals and groups through social capital and social "markets". Sociologists, such as Mark Granovetter, have developed core principles about the interactions of social structure, information, ability to punish or reward, and trust that frequently recur in their analyses of political, economic and other institutions. Granovetter examines how social structures and social networks can affect economic outcomes like hiring, price, productivity and innovation and describes sociologists' contributions to analyzing the impact of social structure and networks on the economy. Analysis of social networks is increasingly incorporated into health care analytics, not only in epidemiological studies but also in models of patient communication and education, disease prevention, mental health diagnosis and treatment, and in the study of health care organizations and systems. Human ecology is an interdisciplinary and transdisciplinary study of the relationship between humans and their natural, social, and built environments. The scientific philosophy of human ecology has a diffuse history with connections to geography, sociology, psychology, anthropology, zoology, and natural ecology. In the study of literary systems, network analysis has been applied by Anheier, Gerhards and Romo, De Nooy, Senekal, and Lotker, to study various aspects of how literature functions. The basic premise is that polysystem theory, which has been around since the writings of Even-Zohar, can be integrated with network theory and the relationships between different actors in the literary network, e.g. writers, critics, publishers, literary histories, etc., can be mapped using visualization from SNA. Research studies of formal or informal organization relationships, organizational communication, economics, economic sociology, and other resource transfers. Social networks have also been used to examine how organizations interact with each other, characterizing the many informal connections that link executives together, as well as associations and connections between individual employees at different organizations. Many organizational social network studies focus on teams. Within team network studies, research assesses, for example, the predictors and outcomes of centrality and power, density and centralization of team instrumental and expressive ties, and the role of between-team networks. Intra-organizational networks have been found to affect organizational commitment, organizational identification, interpersonal citizenship behaviour. Social capital is a form of economic and cultural capital in which social networks are central, transactions are marked by reciprocity, trust, and cooperation, and market agents produce goods and services not mainly for themselves, but for a common good. Social capital is split into three dimensions: the structural, the relational and the cognitive dimension. The structural dimension describes how partners interact with each other and which specific partners meet in a social network. Also, the structural dimension of social capital indicates the level of ties among organizations. This dimension is highly connected to the relational dimension which refers to trustworthiness, norms, expectations and identifications of the bonds between partners. The relational dimension explains the nature of these ties which is mainly illustrated by the level of trust accorded to the network of organizations. The cognitive dimension analyses the extent to which organizations share common goals and objectives as a result of their ties and interactions. Social capital is a sociological concept about the value of social relations and the role of cooperation and confidence to achieve positive outcomes. The term refers to the value one can get from their social ties. For example, newly arrived immigrants can make use of their social ties to established migrants to acquire jobs they may otherwise have trouble getting (e.g., because of unfamiliarity with the local language). A positive relationship exists between social capital and the intensity of social network use. In a dynamic framework, higher activity in a network feeds into higher social capital which itself encourages more activity. This particular cluster focuses on brand-image and promotional strategy effectiveness, taking into account the impact of customer participation on sales and brand-image. This is gauged through techniques such as sentiment analysis which rely on mathematical areas of study such as data mining and analytics. This area of research produces vast numbers of commercial applications as the main goal of any study is to understand consumer behaviour and drive sales. In many organizations, members tend to focus their activities inside their own groups, which stifles creativity and restricts opportunities. A player whose network bridges structural holes has an advantage in detecting and developing rewarding opportunities. Such a player can mobilize social capital by acting as a "broker" of information between two clusters that otherwise would not have been in contact, thus providing access to new ideas, opinions and opportunities. British philosopher and political economist John Stuart Mill, writes, "it is hardly possible to overrate the value of placing human beings in contact with persons dissimilar to themselves.... Such communication [is] one of the primary sources of progress." Thus, a player with a network rich in structural holes can add value to an organization through new ideas and opportunities. This in turn, helps an individual's career development and advancement. A social capital broker also reaps control benefits of being the facilitator of information flow between contacts. Full communication with exploratory mindsets and information exchange generated by dynamically alternating positions in a social network promotes creative and deep thinking. In the case of consulting firm Eden McCallum, the founders were able to advance their careers by bridging their connections with former big three consulting firm consultants and mid-size industry firms. By bridging structural holes and mobilizing social capital, players can advance their careers by executing new opportunities between contacts. There has been research that both substantiates and refutes the benefits of information brokerage. A study of high tech Chinese firms by Zhixing Xiao found that the control benefits of structural holes are "dissonant to the dominant firm-wide spirit of cooperation and the information benefits cannot materialize due to the communal sharing values" of such organizations. However, this study only analyzed Chinese firms, which tend to have strong communal sharing values. Information and control benefits of structural holes are still valuable in firms that are not quite as inclusive and cooperative on the firm-wide level. In 2004, Ronald Burt studied 673 managers who ran the supply chain for one of America's largest electronics companies. He found that managers who often discussed issues with other groups were better paid, received more positive job evaluations and were more likely to be promoted. Thus, bridging structural holes can be beneficial to an organization, and in turn, to an individual's career. Computer networks combined with social networking software produce a new medium for social interaction. A relationship over a computerized social networking service can be characterized by context, direction, and strength. The content of a relation refers to the resource that is exchanged. In a computer-mediated communication context, social pairs exchange different kinds of information, including sending a data file or a computer program as well as providing emotional support or arranging a meeting. With the rise of electronic commerce, information exchanged may also correspond to exchanges of money, goods or services in the "real" world. Social network analysis methods have become essential to examining these types of computer mediated communication. In addition, the sheer size and the volatile nature of social media has given rise to new network metrics. A key concern with networks extracted from social media is the lack of robustness of network metrics given missing data. Based on the pattern of homophily, ties between people are most likely to occur between nodes that are most similar to each other, or within neighbourhood segregation, individuals are most likely to inhabit the same regional areas as other individuals who are like them. Therefore, social networks can be used as a tool to measure the degree of segregation or homophily within a social network. Social Networks can both be used to simulate the process of homophily but it can also serve as a measure of level of exposure of different groups to each other within a current social network of individuals in a certain area. See also References Further reading External links |
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Contents Lod Lod (Hebrew: לוד, fully vocalized: לֹד), also known as Lydda (Ancient Greek: Λύδδα) and Lidd (Arabic: اللِّدّ, romanized: al-Lidd, or اللُّدّ, al-Ludd), is a city 15 km (9+1⁄2 mi) southeast of Tel Aviv and 40 km (25 mi) northwest of Jerusalem in the Central District of Israel. It is situated between the lower Shephelah on the east and the coastal plain on the west. The city had a population of 90,814 in 2023. Lod has been inhabited since at least the Neolithic period. It is mentioned a few times in the Hebrew Bible and in the New Testament. Between the 5th century BCE and up until the late Roman period, it was a prominent center for Jewish scholarship and trade. Around 200 CE, the city became a Roman colony and was renamed Diospolis (Ancient Greek: Διόσπολις, lit. 'city of Zeus'). Tradition identifies Lod as the 4th century martyrdom site of Saint George; the Church of Saint George and Mosque of Al-Khadr located in the city is believed to have housed his remains. Following the Arab conquest of the Levant, Lod served as the capital of Jund Filastin; however, a few decades later, the seat of power was transferred to Ramla, and Lod slipped in importance. Under Crusader rule, the city was a Catholic diocese of the Latin Church and it remains a titular see to this day.[citation needed] Lod underwent a major change in its population in the mid-20th century. Exclusively Palestinian Arab in 1947, Lod was part of the area designated for an Arab state in the United Nations Partition Plan for Palestine; however, in July 1948, the city was occupied by the Israel Defense Forces, and most of its Arab inhabitants were expelled in the Palestinian expulsion from Lydda and Ramle. The city was largely resettled by Jewish immigrants, most of them expelled from Arab countries. Today, Lod is one of Israel's mixed cities, with an Arab population of 30%. Lod is one of Israel's major transportation hubs. The main international airport, Ben Gurion Airport, is located 8 km (5 miles) north of the city. The city is also a major railway and road junction. Religious references The Hebrew name Lod appears in the Hebrew Bible as a town of Benjamin, founded along with Ono by Shamed or Shamer (1 Chronicles 8:12; Ezra 2:33; Nehemiah 7:37; 11:35). In Ezra 2:33, it is mentioned as one of the cities whose inhabitants returned after the Babylonian captivity. Lod is not mentioned among the towns allocated to the tribe of Benjamin in Joshua 18:11–28. The name Lod derives from a tri-consonantal root not extant in Northwest Semitic, but only in Arabic (“to quarrel; withhold, hinder”). An Arabic etymology of such an ancient name is unlikely (the earliest attestation is from the Achaemenid period). In the New Testament, the town appears in its Greek form, Lydda, as the site of Peter's healing of Aeneas in Acts 9:32–38. The city is also mentioned in an Islamic hadith as the location of the battlefield where the false messiah (al-Masih ad-Dajjal) will be slain before the Day of Judgment. History The first occupation dates to the Neolithic in the Near East and is associated with the Lodian culture. Occupation continued in the Levant Chalcolithic. Pottery finds have dated the initial settlement in the area now occupied by the town to 5600–5250 BCE. In the Early Bronze, it was an important settlement in the central coastal plain between the Judean Shephelah and the Mediterranean coast, along Nahal Ayalon. Other important nearby sites were Tel Dalit, Tel Bareqet, Khirbat Abu Hamid (Shoham North), Tel Afeq, Azor and Jaffa. Two architectural phases belong to the late EB I in Area B. The first phase had a mudbrick wall, while the late phase included a circulat stone structure. Later excavations have produced an occupation later, Stratum IV. It consists of two phases, Stratum IVb with mudbrick wall on stone foundations and rounded exterior corners. In Stratum IVa there was a mudbrick wall with no stone foundations, with imported Egyptian potter and local pottery imitations. Another excavations revealed nine occupation strata. Strata VI-III belonged to Early Bronze IB. The material culture showed Egyptian imports in strata V and IV. Occupation continued into Early Bronze II with four strata (V-II). There was continuity in the material culture and indications of centralized urban planning. North to the tell were scattered MB II burials. The earliest written record is in a list of Canaanite towns drawn up by the Egyptian pharaoh Thutmose III at Karnak in 1465 BCE. From the fifth century BCE until the Roman period, the city was a centre of Jewish scholarship and commerce. According to British historian Martin Gilbert, during the Hasmonean period, Jonathan Maccabee and his brother, Simon Maccabaeus, enlarged the area under Jewish control, which included conquering the city. The Jewish community in Lod during the Mishnah and Talmud era is described in a significant number of sources, including information on its institutions, demographics, and way of life. The city reached its height as a Jewish center between the First Jewish-Roman War and the Bar Kokhba revolt, and again in the days of Judah ha-Nasi and the start of the Amoraim period. The city was then the site of numerous public institutions, including schools, study houses, and synagogues. In 43 BC, Cassius, the Roman governor of Syria, sold the inhabitants of Lod into slavery, but they were set free two years later by Mark Antony. During the First Jewish–Roman War, the Roman proconsul of Syria, Cestius Gallus, razed the town on his way to Jerusalem in Tishrei 66 CE. According to Josephus, "[he] found the city deserted, for the entire population had gone up to Jerusalem for the Feast of Tabernacles. He killed fifty people whom he found, burned the town and marched on". Lydda was occupied by Emperor Vespasian in 68 CE. In the period following the destruction of Jerusalem in 70 CE, Rabbi Tarfon, who appears in many Tannaitic and Jewish legal discussions, served as a rabbinic authority in Lod. During the Kitos War, 115–117 CE, the Roman army laid siege to Lod, where the rebel Jews had gathered under the leadership of Julian and Pappos. Torah study was outlawed by the Romans and pursued mostly in the underground. The distress became so great, the patriarch Rabban Gamaliel II, who was shut up there and died soon afterwards, permitted fasting on Ḥanukkah. Other rabbis disagreed with this ruling. Lydda was next taken and many of the Jews were executed; the "slain of Lydda" are often mentioned in words of reverential praise in the Talmud. In 200 CE, emperor Septimius Severus elevated the town to the status of a city, calling it Colonia Lucia Septimia Severa Diospolis. The name Diospolis ("City of Zeus") may have been bestowed earlier, possibly by Hadrian. At that point, most of its inhabitants were Christian. The earliest known bishop is Aëtius, a friend of Arius. During the following century (200-300CE), it's said that Joshua ben Levi founded a yeshiva in Lod. In December 415, the Council of Diospolis was held here to try Pelagius; he was acquitted. In the sixth century, the city was renamed Georgiopolis after St. George, a soldier in the guard of the emperor Diocletian, who was born there between 256 and 285 CE. The Church of Saint George and Mosque of Al-Khadr is named for him. The 6th-century Madaba map shows Lydda as an unwalled city with a cluster of buildings under a black inscription reading "Lod, also Lydea, also Diospolis". An isolated large building with a semicircular colonnaded plaza in front of it might represent the St George shrine. After the Muslim conquest of Palestine by Amr ibn al-'As in 636 CE, Lod which was referred to as "al-Ludd" in Arabic served as the capital of Jund Filastin ("Military District of Palaestina") before the seat of power was moved to nearby Ramla during the reign of the Umayyad Caliph Suleiman ibn Abd al-Malik in 715–716. The population of al-Ludd was relocated to Ramla, as well. With the relocation of its inhabitants and the construction of the White Mosque in Ramla, al-Ludd lost its importance and fell into decay. The city was visited by the local Arab geographer al-Muqaddasi in 985, when it was under the Fatimid Caliphate, and was noted for its Great Mosque which served the residents of al-Ludd, Ramla, and the nearby villages. He also wrote of the city's "wonderful church (of St. George) at the gate of which Christ will slay the Antichrist." The Crusaders occupied the city in 1099 and named it St Jorge de Lidde. It was briefly conquered by Saladin, but retaken by the Crusaders in 1191. For the English Crusaders, it was a place of great significance as the birthplace of Saint George. The Crusaders made it the seat of a Latin Church diocese, and it remains a titular see. It owed the service of 10 knights and 20 sergeants, and it had its own burgess court during this era. In 1226, Ayyubid Syrian geographer Yaqut al-Hamawi visited al-Ludd and stated it was part of the Jerusalem District during Ayyubid rule. Sultan Baybars brought Lydda again under Muslim control by 1267–8. According to Qalqashandi, Lydda was an administrative centre of a wilaya during the fourteenth and fifteenth century in the Mamluk empire. Mujir al-Din described it as a pleasant village with an active Friday mosque. During this time, Lydda was a station on the postal route between Cairo and Damascus. In 1517, Lydda was incorporated into the Ottoman Empire as part of the Damascus Eyalet, and in the 1550s, the revenues of Lydda were designated for the new waqf of Hasseki Sultan Imaret in Jerusalem, established by Hasseki Hurrem Sultan (Roxelana), the wife of Suleiman the Magnificent. By 1596 Lydda was a part of the nahiya ("subdistrict") of Ramla, which was under the administration of the liwa ("district") of Gaza. It had a population of 241 households and 14 bachelors who were all Muslims, and 233 households who were Christians. They paid a fixed tax-rate of 33,3 % on agricultural products, including wheat, barley, summer crops, vineyards, fruit trees, sesame, special product ("dawalib" =spinning wheels), goats and beehives, in addition to occasional revenues and market toll, a total of 45,000 Akçe. All of the revenue went to the Waqf. In 1051 AH/1641/2, the Bedouin tribe of al-Sawālima from around Jaffa attacked the villages of Subṭāra, Bayt Dajan, al-Sāfiriya, Jindās, Lydda and Yāzūr belonging to Waqf Haseki Sultan. The village appeared as Lydda, though misplaced, on the map of Pierre Jacotin compiled in 1799. Missionary William M. Thomson visited Lydda in the mid-19th century, describing it as a "flourishing village of some 2,000 inhabitants, imbosomed in noble orchards of olive, fig, pomegranate, mulberry, sycamore, and other trees, surrounded every way by a very fertile neighbourhood. The inhabitants are evidently industrious and thriving, and the whole country between this and Ramleh is fast being filled up with their flourishing orchards. Rarely have I beheld a rural scene more delightful than this presented in early harvest ... It must be seen, heard, and enjoyed to be appreciated." In 1869, the population of Ludd was given as: 55 Catholics, 1,940 "Greeks", 5 Protestants and 4,850 Muslims. In 1870, the Church of Saint George was rebuilt. In 1892, the first railway station in the entire region was established in the city. In the second half of the 19th century, Jewish merchants migrated to the city, but left after the 1921 Jaffa riots. In 1882, the Palestine Exploration Fund's Survey of Western Palestine described Lod as "A small town, standing among enclosure of prickly pear, and having fine olive groves around it, especially to the south. The minaret of the mosque is a very conspicuous object over the whole of the plain. The inhabitants are principally Moslim, though the place is the seat of a Greek bishop resident of Jerusalem. The Crusading church has lately been restored, and is used by the Greeks. Wells are found in the gardens...." From 1918, Lydda was under the administration of the British Mandate in Palestine, as per a League of Nations decree that followed the Great War. During the Second World War, the British set up supply posts in and around Lydda and its railway station, also building an airport that was renamed Ben Gurion Airport after the death of Israel's first prime minister in 1973. At the time of the 1922 census of Palestine, Lydda had a population of 8,103 inhabitants (7,166 Muslims, 926 Christians, and 11 Jews), the Christians were 921 Orthodox, 4 Roman Catholics and 1 Melkite. This had increased by the 1931 census to 11,250 (10,002 Muslims, 1,210 Christians, 28 Jews, and 10 Bahai), in a total of 2475 residential houses. In 1938, Lydda had a population of 12,750. In 1945, Lydda had a population of 16,780 (14,910 Muslims, 1,840 Christians, 20 Jews and 10 "other"). Until 1948, Lydda was an Arab town with a population of around 20,000—18,500 Muslims and 1,500 Christians. In 1947, the United Nations proposed dividing Mandatory Palestine into two states, one Jewish state and one Arab; Lydda was to form part of the proposed Arab state. In the ensuing war, Israel captured Arab towns outside the area the UN had allotted it, including Lydda. In December 1947, thirteen Jewish passengers in a seven-car convoy to Ben Shemen Youth Village were ambushed and murdered.In a separate incident, three Jewish youths, two men and a woman were captured, then raped and murdered in a neighbouring village. Their bodies were paraded in Lydda’s principal street. The Israel Defense Forces entered Lydda on 11 July 1948. The following day, under the impression that it was under attack, the 3rd Battalion was ordered to shoot anyone "seen on the streets". According to Israel, 250 Arabs were killed. Other estimates are higher: Arab historian Aref al Aref estimated 400, and Nimr al Khatib 1,700. In 1948, the population rose to 50,000 during the Nakba, as Arab refugees fleeing other areas made their way there. A key event was the Palestinian expulsion from Lydda and Ramle, with the expulsion of 50,000-70,000 Palestinians from Lydda and Ramle by the Israel Defense Forces. All but 700 to 1,056 were expelled by order of the Israeli high command, and forced to walk 17 km (10+1⁄2 mi) to the Jordanian Arab Legion lines. Estimates of those who died from exhaustion and dehydration vary from a handful to 355. The town was subsequently sacked by the Israeli army. Some scholars, including Ilan Pappé, characterize this as ethnic cleansing. The few hundred Arabs who remained in the city were soon outnumbered by the influx of Jews who immigrated to Lod from August 1948 onward, most of them from Arab countries. As a result, Lod became a predominantly Jewish town. After the establishment of the state, the biblical name Lod was readopted. The Jewish immigrants who settled Lod came in waves, first from Morocco and Tunisia, later from Ethiopia, and then from the former Soviet Union. Since 2008, many urban development projects have been undertaken to improve the image of the city. Upscale neighbourhoods have been built, among them Ganei Ya'ar and Ahisemah, expanding the city to the east. According to a 2010 report in the Economist, a three-meter-high wall was built between Jewish and Arab neighbourhoods and construction in Jewish areas was given priority over construction in Arab neighborhoods. The newspaper says that violent crime in the Arab sector revolves mainly around family feuds over turf and honour crimes. In 2010, the Lod Community Foundation organised an event for representatives of bicultural youth movements, volunteer aid organisations, educational start-ups, businessmen, sports organizations, and conservationists working on programmes to better the city. In the 2021 Israel–Palestine crisis, a state of emergency was declared in Lod after Arab rioting led to the death of an Israeli Jew. The Mayor of Lod, Yair Revivio, urged Prime Minister of Israel Benjamin Netanyahu to deploy Israel Border Police to restore order in the city. This was the first time since 1966 that Israel had declared this kind of emergency lockdown. International media noted that both Jewish and Palestinian mobs were active in Lod, but the "crackdown came for one side" only. Demographics In the 19th century and until the Lydda Death March, Lod was an exclusively Muslim-Christian town, with an estimated 6,850 inhabitants, of whom approximately 2,000 (29%) were Christian. According to the Israel Central Bureau of Statistics (CBS), the population of Lod in 2010 was 69,500 people. According to the 2019 census, the population of Lod was 77,223, of which 53,581 people, comprising 69.4% of the city's population, were classified as "Jews and Others", and 23,642 people, comprising 30.6% as "Arab". Education According to CBS, 38 schools and 13,188 pupils are in the city. They are spread out as 26 elementary schools and 8,325 elementary school pupils, and 13 high schools and 4,863 high school pupils. About 52.5% of 12th-grade pupils were entitled to a matriculation certificate in 2001.[citation needed] Economy The airport and related industries are a major source of employment for the residents of Lod. Other important factories in the city are the communication equipment company "Talard", "Cafe-Co" - a subsidiary of the Strauss Group and "Kashev" - the computer center of Bank Leumi. A Jewish Agency Absorption Centre is also located in Lod. According to CBS figures for 2000, 23,032 people were salaried workers and 1,405 were self-employed. The mean monthly wage for a salaried worker was NIS 4,754, a real change of 2.9% over the course of 2000. Salaried men had a mean monthly wage of NIS 5,821 (a real change of 1.4%) versus NIS 3,547 for women (a real change of 4.6%). The mean income for the self-employed was NIS 4,991. About 1,275 people were receiving unemployment benefits and 7,145 were receiving an income supplement. Art and culture In 2009-2010, Dor Guez held an exhibit, Georgeopolis, at the Petach Tikva art museum that focuses on Lod. Archaeology A well-preserved mosaic floor dating to the Roman period was excavated in 1996 as part of a salvage dig conducted on behalf of the Israel Antiquities Authority and the Municipality of Lod, prior to widening HeHalutz Street. According to Jacob Fisch, executive director of the Friends of the Israel Antiquities Authority, a worker at the construction site noticed the tail of a tiger and halted work. The mosaic was initially covered over with soil at the conclusion of the excavation for lack of funds to conserve and develop the site. The mosaic is now part of the Lod Mosaic Archaeological Center. The floor, with its colorful display of birds, fish, exotic animals and merchant ships, is believed to have been commissioned by a wealthy resident of the city for his private home. The Lod Community Archaeology Program, which operates in ten Lod schools, five Jewish and five Israeli Arab, combines archaeological studies with participation in digs in Lod. Sports The city's major football club, Hapoel Bnei Lod, plays in Liga Leumit (the second division). Its home is at the Lod Municipal Stadium. The club was formed by a merger of Bnei Lod and Rakevet Lod in the 1980s. Two other clubs in the city play in the regional leagues: Hapoel MS Ortodoxim Lod in Liga Bet and Maccabi Lod in Liga Gimel. Hapoel Lod played in the top division during the 1960s and 1980s, and won the State Cup in 1984. The club folded in 2002. A new club, Hapoel Maxim Lod (named after former mayor Maxim Levy) was established soon after, but folded in 2007. Notable people Twin towns-sister cities Lod is twinned with: See also References Bibliography External links |
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