title: Safavid Iran

text: Between 1508 and 1524, the year of Ismail's death, the shah appointed five successive Persians to the office of "vakil". When the second Persian vakil was placed in command of a Safavid army in Transoxiana, the Qizilbash, considering it a dishonor to be obliged to serve under him, deserted him on the battlefield with the result that he was slain. The fourth vakil was murdered by the Qizilbash, and the fifth was put to death by them.


title: Safavid Iran

text: Shah Abbas realized that in order to retain absolute control over his empire without antagonizing the Qizilbash, he needed to create reforms that reduced the dependency that the shah had on their military support. Part of these reforms was the creation of the 3rd force within the aristocracy and all other functions within the empire, but even more important in undermining the authority of the Qizilbash was the introduction of the Royal Corps into the military. This military force would serve the shah only and eventually consisted of four separate branches:


title: Safavid Iran

text: Despite the reforms, the Qizilbash would remain the strongest and most effective element within the military, accounting for more than half of its total strength. But the creation of this large standing army, that, for the first time in Safavid history, was serving directly under the Shah, significantly reduced their influence, and perhaps any possibilities for the type of civil unrest that had caused havoc during the reign of the previous shahs.


title: Safavid Iran

text: The growth of Safavid economy was fuelled by the stability which allowed the agriculture to thrive, as well as trade, due to Iran's position between the burgeoning civilizations of Europe to its west and India and Islamic Central Asia to its east and north. The Silk Road which led through northern Iran was revived in the 16th century. Abbas I also supported direct trade with Europe, particularly England and The Netherlands which sought Persian carpet, silk and textiles. Other exports were horses, goat hair, pearls and an inedible bitter almond hadam-talka used as a spice in India. The main imports were spice, textiles (woolens from Europe, cottons from Gujarat), metals, coffee, and sugar.


title: Safavid Iran

text: In the late 17th century, Safavid Iran had higher living standards than in Europe. According to traveller Jean Chardin, for example, farmers in Iran had higher living standards than farmers in the most fertile European countries.


title: Safavid Iran

text: According to the historian Roger Savory, the twin bases of the domestic economy were pastoralism and agriculture. And, just as the higher levels of the social hierarchy was divided between the Turkish "men of the sword" and the Persian "men of the pen"; so were the lower level divided between the Turcoman tribes, who were cattle breeders and lived apart from the surrounding population, and the Persians, who were settled agriculturalists.


title: Safavid Iran

text: The Safavid economy was to a large extent based on agriculture and taxation of agricultural products. According to the French jeweller Jean Chardin, the variety in agricultural products in Iran was unrivaled in Europe and consisted of fruits and vegetables never even heard of in Europe. Chardin was present at some feasts in Isfahan were there were more than fifty different kinds of fruit. He thought that there was nothing like it in France or Italy:


title: Safavid Iran

text: Despite this, he was disappointed when travelling the country and witnessing the abundance of land that was not irrigated, or the fertile plains that were not cultivated, something he thought was in stark contrast to Europe. He blamed this on misgovernment, the sparse population of the country, and lack of appreciation of agriculture amongst the Persians.


title: Safavid Iran

text: In the period prior to Shah Abbas I, most of the land was assigned to officials (civil, military and religious). From the time of Shah Abbas onwards, more land was brought under the direct control of the shah. And since agriculture accounted for by far largest share of tax revenue, he took measures to expand it. What remained unchanged, was the ""crop-sharing agreement"" between whomever was the landlord, and the farmer. This agreement concisted of five elements: land, water, plough-animals, seed and labour. Each element constituted 20 percent of the crop production, and if, for instance, the farmer provided the labour force and the animals, he would be entitled to 40 percent of the earnings. According to contemporary historians, though, the landlord always had the worst of the bargain with the farmer in the crop-sharing agreements. In general, the farmers lived in comfort, and they were well paid and wore good clothes, although it was also noted that they were subject to forced labour and lived under heavy demands.


title: Safavid Iran

text: Horses were the most important of all the beasts of burden, and the best were brought in from Arabia and Central-Asia. They were costly because of the widespread trade in them, including to Turkey and India. The next most important mount, when traveling through Iran, was the mule. Also, the camel was a good investment for the merchant, as they cost nearly nothing to feed, carried a lot weight and could travel almost anywhere.


title: Safavid Iran

text: Under the governance of the strong shahs, especially during the first half of the 17th century, traveling through Iran was easy because of good roads and the caravanserais, that were strategically placed along the route. Thévenot and Tavernier commented that the Iranian caravanserais were better built and cleaner than their Turkish counterparts. According to Chardin, they were also more abundant than in the Mughal or Ottoman Empires, where they were less frequent but larger. Caravanserais were designed especially to benefit poorer travelers, as they could stay there for as long as they wished, without payment for lodging. During the reign of Shah Abbas I, as he tried to upgrade the Silk Road to improve the commercial prosperity of the Empire, an abundance of caravanserais, bridges, bazaars and roads were built, and this strategy was followed by wealthy merchants who also profited from the increase in trade. To uphold the standard, another source of revenue was needed, and road toll, that were collected by guards ("rah-dars"), were stationed along the trading routes. They in turn provided for the safety of the travelers, and both Thevenot and Tavernier stressed the safety of traveling in 17th century Iran, and the courtesy and refinement of the policing guards. The Italian traveler Pietro Della Valle was impressed by an encounter with one of these road guards:


title: Safavid Iran

text: The Portuguese Empire and the discovery of the trading route around the Cape of Good Hope in 1487 not only hit a death blow to Venice as a trading nation, but it also hurt the trade that was going on along the Silk Road and especially the Persian Gulf. They correctly identified the three key points to control all seaborne trade between Asia and Europe: The Gulf of Aden, The Persian Gulf and the Straits of Malacca by cutting off and controlling these strategic locations with high taxation. In 1602, Shah Abbas I drove the Portuguese out of Bahrain, but he needed naval assistance from the newly arrived British East India Company to finally expel them from the Strait of Hormuz and regain control of this trading route. He convinced the British to assist him by allowing them to open factories in Shiraz, Isfahan and Jask. With the later end of the Portuguese Empire, the British, Dutch and French in particular gained easier access to Persian seaborne trade, although they, unlike the Portuguese, did not arrive as colonisers, but as merchant adventurers. The terms of trade were not imposed on the Safavid shahs, but rather negotiated.


title: Safavid Iran

text: Furthermore, the Safavids maintained a sizeable sphere of influence overseas, particularly in the Deccan region of India. The Sultanates of Ahmednagar, Bijapur, and Golconda all sought Persian suzerainty not just because of religious or cultural ties, but also because of the need for a counterweight to Mughal expansion. The Persians complied, and thousands of Persians emigrated to the Deccan during the 16th and 17th centuries, continuing a process that already began under the Bahmani Sultanate of the Deccan. From here, Persian traders ventured eastwards to Southeast Asian kingdoms, most notably Ayutthaya Siam, where influential Persian families like the Bunnag helped foster cordial diplomatic relations between Thailand and Iran, as evidenced in the expedition of Suleyman's Ship. The Persians were also active in the Aceh Sultanate, the Brunei Sultanate, the Demak Sultanate, and Dai Viet.


title: Safavid Iran

text: In the long term, however, the seaborne trade route was of less significance to the Persians than was the traditional Silk Road. Lack of investment in ship building and the navy provided the Europeans with the opportunity to monopolize this trading route. The land-borne trade would thus continue to provide the bulk of revenues to the Iranian state from transit taxes. The revenue came not so much from exports, as from the custom charges and transit dues levied on goods passing through the country. Shah Abbas was determined to greatly expand this trade, but faced the problem of having to deal with the Ottomans, who controlled the two most vital routes: the route across Arabia to the Mediterranean ports, and the route through Anatolia and Istanbul. A third route was therefore devised which circumvented Ottoman territory. By travelling across the Caspian sea to the north, they would reach Russia. And with the assistance of the Muscovy Company they could cross over to Moscow, reaching Europe via Poland. This trading route proved to be of vital importance, especially during times of war with the Ottomans.


title: Safavid Iran

text: By the end of the 17th century, the Dutch had become dominant in the trade that went via the Persian Gulf, having won most trade agreements, and managed to strike deals before the British or French were able to. They particularly established monopoly of the spice and porcelain trade between the Far East and Iran. Protected by Dutch naval power, competition from Bengali silk and Sino-Japanese porcelain contributed to the decline of the Safavid economy during the late 17th century.


title: Safavid Iran

text: Abbas I recognized the commercial benefit of promoting the arts—artisan products provided much of Iran's foreign trade. In this period, handicrafts such as tile making, pottery and textiles developed and great advances were made in miniature painting, bookbinding, decoration and calligraphy. In the 16th century, carpet weaving evolved from a nomadic and peasant craft to a well-executed industry with specialization of design and manufacturing. Tabriz was the center of this industry. The carpets of Ardabil were commissioned to commemorate the Safavid dynasty. The elegantly baroque yet famously 'Polonaise' carpets were made in Iran during the 17th century.


title: Safavid Iran

text: Using traditional forms and materials, Reza Abbasi (1565–1635) introduced new subjects to Persian painting—semi-nude women, youth, lovers. His painting and calligraphic style influenced Iranian artists for much of the Safavid period, which came to be known as the Isfahan school. Increased contact with distant cultures in the 17th century, especially Europe, provided a boost of inspiration to Iranian artists who adopted modeling, foreshortening, spatial recession, and the medium of oil painting (Shah Abbas II sent Muhammad Zaman to study in Rome). The epic "Shahnameh" ("Book of Kings"), a stellar example of manuscript illumination and calligraphy, was made during Shah Tahmasp's reign. (This book was written by Ferdousi in 1000 AD for Sultan Mahmood Ghaznawi) Another manuscript is the Khamsa by Nizami executed 1539–1543 by Aqa Mirak and his school in Isfahan.


title: Safavid Iran

text: Isfahan bears the most prominent samples of the Safavid architecture, all constructed in the years after Shah Abbas I permanently moved the capital there in 1598: the Imperial Mosque, Masjid-e Shah, completed in 1630, the Imam Mosque (Masjid-e Imami) the Lutfallah Mosque and the Royal Palace.


title: Safavid Iran

text: According to William Cleveland and Martin Bunton, the establishment of Isfahan as the Great capital of Iran and the material splendor of the city attracted intellectual's from all corners of the world, which contributed to the city's rich cultural life. The impressive achievements of its 400,000 residents prompted the inhabitants to coin their famous boast, "Isfahan is half the world".


title: Safavid Iran

text: A new age in Iranian architecture began with the rise of the Safavid dynasty. Economically robust and politically stable, this period saw a flourishing growth of theological sciences. Traditional architecture evolved in its patterns and methods leaving its impact on the architecture of the following periods.


title: Safavid Iran

text: Indeed, one of the greatest legacies of the Safavids is the architecture. In 1598, when Shah Abbas decided to move the capital of his Iranian empire from the north-western city of Qazvin to the central city of Isfahan, he initiated what would become one of the greatest programmes in Iranian history; the complete remaking of the city. By choosing the central city of Isfahan, fertilized by the Zāyande roud ("The "life-giving river""), lying as an oasis of intense cultivation in the midst of a vast area of arid landscape, he both distanced his capital from any future assaults by the Ottomans and the Uzbeks, and at the same time gained more control over the Persian Gulf, which had recently become an important trading route for the Dutch and British East India Companies.


title: Safavid Iran

text: The Chief architect of this colossal task of urban planning was Shaykh Bahai (Baha' ad-Din al-`Amili), who focused the programme on two key features of Shah Abbas's master plan: the Chahar Bagh avenue, flanked at either side by all the prominent institutions of the city, such as the residences of all foreign dignitaries. And the Naqsh-e Jahan Square (""Examplar of the World""). Prior to the Shah's ascent to power, Iran had a decentralized power-structure, in which different institutions battled for power, including both the military (the Qizilbash) and governors of the different provinces making up the empire. Shah Abbas wanted to undermine this political structure, and the recreation of Isfahan, as a Grand capital of Iran, was an important step in centralizing the power. The ingenuity of the square, or "Maidān", was that, by building it, Shah Abbas would gather the three main components of power in Iran in his own backyard; the power of the clergy, represented by the Masjed-e Shah, the power of the merchants, represented by the Imperial Bazaar, and of course, the power of the Shah himself, residing in the Ali Qapu Palace.


title: Safavid Iran

text: Distinctive monuments like the Sheikh Lotfallah (1618), Hasht Behesht (Eight Paradise Palace) (1469) and the Chahar Bagh School (1714) appeared in Isfahan and other cities. This extensive development of architecture was rooted in Persian culture and took form in the design of schools, baths, houses, caravanserai and other urban spaces such as bazaars and squares. It continued until the end of the Qajar reign.


title: Safavid Iran

text: Poetry stagnated under the Safavids; the great medieval ghazal form languished in over-the-top lyricism. Poetry lacked the royal patronage of other arts and was hemmed in by religious prescriptions.


title: Safavid Iran

text: The arguably most renowned historian from this time was Iskandar Beg Munshi. His "History of Shah Abbas the Great" written a few years after its subject's death, achieved a nuanced depth of history and character.


title: Safavid Iran

text: Islamic philosophy flourished in the Safavid era in what scholars commonly refer to the School of Isfahan. Mir Damad is considered the founder of this school. Among luminaries of this school of philosophy, the names of Iranian philosophers such as Mir Damad, Mir Fendereski, Shaykh Bahai and Mohsen Fayz Kashani standout. The school reached its apogee with that of the Iranian philosopher Mulla Sadra who is arguably the most significant Islamic philosopher after Avicenna. Mulla Sadra has become the dominant philosopher of the Islamic East, and his approach to the nature of philosophy has been exceptionally influential up to this day. He wrote the "Al-Hikma al-muta‘aliya fi-l-asfar al-‘aqliyya al-arba‘a" ("The Transcendent Philosophy of the Four Journeys of the Intellect"), a meditation on what he called 'meta philosophy' which brought to a synthesis the philosophical mysticism of Sufism, the theology of Shi'a Islam, and the Peripatetic and Illuminationist philosophies of Avicenna and Suhrawardi."


title: Safavid Iran

text: The status of physicians during the Safavids stood as high as ever. Whereas neither the ancient Greeks nor the Romans accorded high social status to their doctors, Iranians had from ancient times honored their physicians, who were often appointed counselors of the Shahs. This would not change with the Arab conquest of Iran, and it was primarily the Persians that took upon them the works of philosophy, logic, medicine, mathematics, astronomy, astrology, music and alchemy.


title: Safavid Iran

text: By the sixteenth century, Islamic science, which to a large extent meant Persian science, was resting on its laurels. The works of al-Razi (865–92) (known to the West as Razes) were still used in European universities as standard textbooks of alchemy, pharmacology and pediatrics. The Canon of Medicine by Avicenna (c. 980–1037) was still regarded as one of the primary textbooks in medicine throughout most of the civilized world. As such, the status of medicine in the Safavid period did not change much, and relied as much on these works as ever before. Physiology was still based on the four humours of ancient and mediaeval medicine, and bleeding and purging were still the principal forms of therapy by surgeons, something even Thevenot experienced during his visit to Iran.


title: Safavid Iran

text: The only field within medicine where some progress were made was pharmacology, with the compilement of the "Tibb-e Shifa’i" in 1556. This book was translated into French in 1681 by Angulus de Saint, under the name "Pharmacopoea Persica".


title: Safavid Iran

text: The Safavids by the time of their rise were Azerbaijani-speaking although they also used Persian as a second language.


title: Safavid Iran

text: The language chiefly used by the Safavid court and military establishment was Azerbaijani. But the official language of the empire as well as the administrative language, language of correspondence, literature and historiography was Persian. The inscriptions on Safavid currency were also in Persian.


title: Safavid Iran

text: Safavids also used Persian as a cultural and administrative language throughout the empire and were bilingual in Persian. According to Arnold J. Toynbee,


title: Safavid Iran

text: It was the Safavids who made Iran the spiritual bastion of Shiʻism, and the repository of Persian cultural traditions and self-awareness of Iranianhood, acting as a bridge to modern Iran. The founder of the dynasty, Shah Isma'il, adopted the title of "King of Iran" ("Pādišah-ī Īrān"), with its implicit notion of an Iranian state stretching from Khorasan as far as Euphrates, and from the Oxus to the southern Territories of the Persian Gulf. According to Professor Roger Savory:


title: Safavid Iran

text: According to Donald Struesand, "although the Safavid unification of the eastern and western halves of the Iranian plateau and imposition of Twelver Shiʻi Islam on the region created a recognizable precursor of modern Iran, the Safavid polity itself was neither distinctively Iranian nor national." Rudolph Matthee concluded that "though not a nation-state, Safavid Iran contained the elements that would later spawn one by generating many enduring bureaucratic features and by initiating a polity of overlapping religious and territorial boundaries."


title: Golgi apparatus

text: The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination. It resides at the intersection of the secretory, lysosomal, and endocytic pathways. It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus.


title: Golgi apparatus

text: Owing to its large size and distinctive structure, the Golgi apparatus was one of the first organelles to be discovered and observed in detail. It was discovered in 1898 by Italian physician Camillo Golgi during an investigation of the nervous system. After first observing it under his microscope, he termed the structure as "apparato reticolare interno" ("internal reticular apparatus"). Some doubted the discovery at first, arguing that the appearance of the structure was merely an optical illusion created by the observation technique used by Golgi. With the development of modern microscopes in the twentieth century, the discovery was confirmed. Early references to the Golgi apparatus referred to it by various names including the "Golgi–Holmgren apparatus", "Golgi–Holmgren ducts", and "Golgi–Kopsch apparatus". The term "Golgi apparatus" was used in 1910 and first appeared in the scientific literature in 1913, while "Golgi complex" was introduced in 1956.


title: Golgi apparatus

text: The subcellular localization of the Golgi apparatus varies among eukaryotes. In mammals, a single Golgi apparatus is usually located near the cell nucleus, close to the centrosome. Tubular connections are responsible for linking the stacks together. Localization and tubular connections of the Golgi apparatus are dependent on microtubules. In experiments it is seen that as microtubules are depolymerized the Golgi apparatuses lose mutual connections and become individual stacks throughout the cytoplasm. In yeast, multiple Golgi apparatuses are scattered throughout the cytoplasm (as observed in "Saccharomyces cerevisiae"). In plants, Golgi stacks are not concentrated at the centrosomal region and do not form Golgi ribbons. Organization of the plant Golgi depends on actin cables and not microtubules. The common feature among Golgi is that they are adjacent to endoplasmic reticulum (ER) exit sites.


title: Golgi apparatus

text: In most eukaryotes, the Golgi apparatus is made up of a series of compartments and is a collection of fused, flattened membrane-enclosed disks known as cisternae (singular: "cisterna", also called "dictyosomes"), originating from vesicular clusters that bud off the endoplasmic reticulum. A mammalian cell typically contains 40 to 100 stacks of cisternae. Between four and eight cisternae are usually present in a stack; however, in some protists as many as sixty cisternae have been observed. This collection of cisternae is broken down into "cis", medial, and "trans" compartments, making up two main networks: the cis Golgi network (CGN) and the trans Golgi network (TGN). The CGN is the first cisternal structure, and the TGN is the final, from which proteins are packaged into vesicles destined to lysosomes, secretory vesicles, or the cell surface. The TGN is usually positioned adjacent to the stack, but can also be separate from it. The TGN may act as an early endosome in yeast and plants.


title: Golgi apparatus

text: There are structural and organizational differences in the Golgi apparatus among eukaryotes. In some yeasts, Golgi stacking is not observed. "Pichia pastoris" does have stacked Golgi, while "Saccharomyces cerevisiae" does not. In plants, the individual stacks of the Golgi apparatus seem to operate independently.


title: Golgi apparatus

text: The Golgi apparatus tends to be larger and more numerous in cells that synthesize and secrete large amounts of substances; for example, the antibody-secreting plasma B cells of the immune system have prominent Golgi complexes.


title: Golgi apparatus

text: In all eukaryotes, each cisternal stack has a "cis" entry face and a "trans" exit face. These faces are characterized by unique morphology and biochemistry. Within individual stacks are assortments of enzymes responsible for selectively modifying protein cargo. These modifications influence the fate of the protein. The compartmentalization of the Golgi apparatus is advantageous for separating enzymes, thereby maintaining consecutive and selective processing steps: enzymes catalyzing early modifications are gathered in the "cis" face cisternae, and enzymes catalyzing later modifications are found in "trans" face cisternae of the Golgi stacks.


title: Golgi apparatus

text: The Golgi apparatus is a major collection and dispatch station of protein products received from the endoplasmic reticulum (ER). Proteins synthesized in the ER are packaged into vesicles, which then fuse with the Golgi apparatus. These cargo proteins are modified and destined for secretion via exocytosis or for use in the cell.


title: Golgi apparatus

text: In this respect, the Golgi can be thought of as similar to a post office: it packages and labels items which it then sends to different parts of the cell or to the extracellular space. The Golgi apparatus is also involved in lipid transport and lysosome formation.


title: Golgi apparatus

text: The structure and function of the Golgi apparatus are intimately linked. Individual stacks have different assortments of enzymes, allowing for progressive processing of cargo proteins as they travel from the cisternae to the trans Golgi face. Enzymatic reactions within the Golgi stacks occur exclusively near its membrane surfaces, where enzymes are anchored. This feature is in contrast to the ER, which has soluble proteins and enzymes in its lumen. Much of the enzymatic processing is post-translational modification of proteins. For example, phosphorylation of oligosaccharides on lysosomal proteins occurs in the early CGN. "Cis" cisterna are associated with the removal of mannose residues. Removal of mannose residues and addition of N-acetylglucosamine occur in medial cisternae. Addition of galactose and sialic acid occurs in the "trans" cisternae. Sulfation of tyrosines and carbohydrates occurs within the TGN. Other general post-translational modifications of proteins include the addition of carbohydrates (glycosylation) and phosphates (phosphorylation). Protein modifications may form a signal sequence that determines the final destination of the protein. For example, the Golgi apparatus adds a mannose-6-phosphate label to proteins destined for lysosomes. Another important function of the Golgi apparatus is in the formation of proteoglycans. Enzymes in the Golgi append proteins to glycosaminoglycans, thus creating proteoglycans. Glycosaminoglycans are long unbranched polysaccharide molecules present in the extracellular matrix of animals.


title: Golgi apparatus

text: The vesicles that leave the rough endoplasmic reticulum are transported to the "cis" face of the Golgi apparatus, where they fuse with the Golgi membrane and empty their contents into the lumen. Once inside the lumen, the molecules are modified, then sorted for transport to their next destinations.


title: Golgi apparatus

text: Those proteins destined for areas of the cell other than either the endoplasmic reticulum or the Golgi apparatus are moved through the Golgi cisternae towards the "trans" face, to a complex network of membranes and associated vesicles known as the "trans-Golgi network" (TGN). This area of the Golgi is the point at which proteins are sorted and shipped to their intended destinations by their placement into one of at least three different types of vesicles, depending upon the signal sequence they carry.


title: Golgi apparatus

text: Though there are multiple models that attempt to explain vesicular traffic throughout the Golgi, no individual model can independently explain all observations of the Golgi apparatus. Currently, the cisternal progression/maturation model is the most accepted among scientists, accommodating many observations across eukaryotes. The other models are still important in framing questions and guiding future experimentation. Among the fundamental unanswered questions are the directionality of COPI vesicles and role of Rab GTPases in modulating protein cargo traffic.


title: Golgi apparatus

text: Brefeldin A (BFA) is a fungal metabolite used experimentally to disrupt the secretion pathway as a method of testing Golgi function. BFA blocks the activation of some ADP-ribosylation factors (ARFs). ARFs are small GTPases which regulate vesicular trafficking through the binding of COPs to endosomes and the Golgi. BFA inhibits the function of several guanine nucleotide exchange factors (GEFs) that mediate GTP-binding of ARFs. Treatment of cells with BFA thus disrupts the secretion pathway, promoting disassembly of the Golgi apparatus and distributing Golgi proteins to the endosomes and ER.


title: Viber

text: Viber, or Rakuten Viber, is a cross-platform voice over IP (VoIP) and instant messaging (IM) software application owned by Japanese multinational company Rakuten, provided as freeware for the Google Android, iOS, Microsoft Windows, Apple macOS and Linux platforms. Users are registered and identified through a cellular telephone number, although the service is accessible on desktop platforms without needing mobile connectivity. In addition to instant messaging it allows users to exchange media such as images and video records, and also provides a paid international landline and mobile calling service called Viber Out. As of 2018, there are over a billion registered users on the network.


title: Viber

text: The software was developed in 2010 by Cyprus-based Viber Media, which was bought by Rakuten in 2014. Since 2017, its corporate name has been Rakuten Viber. It is based in Cyprus with offices in London, Manila, Moscow, Paris, San Francisco, Singapore, and Tokyo.


title: Viber

text: Viber Media was founded in Tel Aviv, Israel, in 2010 by Talmon Marco and [[Igo Magazinnik}}, who are friends from the [[Israel Defense Forces]] where they were chief information officers. Marco and Magazinnik are also co-founders of the [[Peer-to-peer|P2P]] media and file-sharing client [[iMesh]]. The company was run from Israel, and was registered in [[Cyprus]]. Sani Maroli and Ofer Smocha soon joined the company as well. Marco commented that Viber allows instant calling and synchronization with contacts because the ID is the user's cell number.


title: Viber

text: In its first two years of availability, Viber did not generate revenues. It began doing so in 2013, via user payments for Viber Out voice calling and the Viber graphical messaging "sticker market". The company was originally funded by individual investors, described by Marco as "friends and family". They invested $20 million in the company, which had 120 employees .


title: Viber

text: On 24 July 2013, Viber's support system was defaced by the [[Syrian Electronic Army]]. According to Viber, no sensitive user information was accessed.


title: Viber

text: On 13 February 2014, [[Rakuten]] announced they had acquired Viber Media for $900 million. The sale of Viber earned the Shabtai family ([[Benny Shabtai|Benny]], his brother Gilad, and Gilad's son Ofer) some $500 million from their 55.2% stake in the company. At that sale price, the founders each realized over 30 times return on their investments.


title: Viber

text: Djamel Agaoua became Viber Media [[CEO]] in February 2017, replacing co-founder Marco who left in 2015.


title: Viber

text: In July 2017 the corporate name of Viber Media was changed to Rakuten Viber and a new [[wordmark]] logo was introduced. Its [[legal name]] remains "Viber Media, [[S.à r.l.]]" based in Luxembourg.


title: Viber

text: In 2017, Rakuten Viber and the [[World Wildlife Fund]] engaged in a commercial transaction aimed at raising awareness and protecting wildlife.


title: Viber

text: After first using RV to spread its message in June 2020, the [[International Federation of the Red Cross]] launched an official chatbot and Community on the messaging app to combat the spread of false information, which they termed an [[infodemic]], about COVID-19. The chatbot is still active as of June 2022, with over 1.4 million subscribers.


title: Viber

text: In 2020, Rakuten Viber and the [[World Health Organization]] (the WHO) engaged in a commercial transaction for a chatbot to inform users of issues such as women’s health. and an anti-smoking campaign.


title: Viber

text: In the wake of the July-August 2020 Belarusian election protests and ensuing crackdown, the company closed its office in Minsk.


title: Viber

text: On 4 November 2014, Viber scored 1 out of 7 points on the [[Electronic Frontier Foundation]]'s "Secure Messaging Scorecard". Viber received a point for encryption during transit but lost points because communications were not encrypted with keys that the provider did not have access to (i.e. the communications were not [[End-to-end encryption|end-to-end encrypted]]), users could not verify contacts' identities, past messages were not secure if the encryption keys were stolen (i.e. the service did not provide [[forward secrecy]]), the code was not open to independent review (i.e. the code was not [[Open-source software|open-source]]), the security design was not properly documented, and there had not been a recent independent [[Information technology security audit|security audit]]. On 14 November 2014, the EFF changed Viber's score to 2 out of 7 after it had received an external security audit from [[Ernst & Young]]'s Advanced Security Centre.


title: Viber

text: On 19 April 2016, with the announcement of Viber version 6.0, Rakuten added end-to-end encryption to their service, but only for one-to-one and group conversations in which all participants are using the latest Viber version for Android, iOS, Windows ([[Win32]]) or Windows 10 ([[Universal Windows Platform|UWP]]). The company said that the [[encryption protocol]] had only been audited internally, and promised to commission external audits "in the coming weeks". In May 2016, Viber published an overview of their encryption protocol, saying that it is a custom implementation that "uses the same concepts" as the [[Signal Protocol]].


title: Viber

text: , Viber had 800 million registered users. According to [[Statista]], there are 260 million monthly active users as of January 2019. The Viber messenger is very popular in [[Greece]], [[Eastern Europe]], [[Russia]], the [[Middle East]], and some [[Asia]]n markets.


title: Viber

text: [[India]] was the largest market for Viber as of December 2014 with 33 million registered users, the fifth most popular instant messenger in the country. At the same time there were 30 million users in the [[United States]], 28 million in [[Russia]] and 18 million in [[Brazil]]. Viber is particularly popular in Eastern Europe, being the most downloaded messaging app on Android in [[Belarus]], [[Moldova]] and [[Ukraine]] as of 2016. It is also popular in [[Iraq]], [[Libya]] and [[Nepal]].


title: Viber

text: As of 2018, Viber had an over 70 percent penetration rate in the [[Commonwealth of Independent States|CIS]] and [[Central and Eastern Europe|CEE]] regions, but only 15 percent in North America.


title: Viber

text: As of September 2021, Viber is Ukraine’s most popular messaging app, with a market share of 97.7%. 20% of the company’s total messages sent came from Ukraine, where users sent 97.5 billion messages in 2021.


title: Viber

text: Viber’s market share in Bulgaria is steadily increasing. Reaching a record 90% in 2021. The number of calls made and messages sent via Viber in Bulgaria rose by 11% in 2021, reaching approximately 530 million calls and an average of 400 messages per second, according to data presented by the company.


title: Viber

text: As of the end of 2021, over 90% of people in Greece have Viber on their phones, making it the top messaging app in the country.


title: Viber

text: Viber is the top messenger in Serbia. As of November 2021, over 90% of Serbians have Viber on their phone.


title: Viber

text: Viber was initially launched for [[iPhone]] on 2 December 2010. It was launched on [[BlackBerry]] and [[Windows Phone]] on 8 May 2012, followed by the [[Android (operating system)|Android]] platform on 19 July 2012, and Nokia's [[Series 40]], [[Symbian]] and Samsung's [[Bada]] platform on 24 July 2012, by which time the application had 90 million users.


title: Viber

text: In May 2013 with Viber 3.0, a desktop version for [[Windows]] and [[macOS]] was released. In August 2013, Viber for [[Linux]] was released as a public [[Beta test|beta]] and in August 2014 a final version. In June 2016 a [[Universal Windows Platform|UWP]]-based desktop application for [[Windows 10]] was released in the [[Windows Store]]. The desktop versions are tied with a user's registered Viber mobile number, but can operate independently afterwards. In 2015, a version for the [[iPad]] tablet and [[Apple Watch]] smartwatch was released.


title: Viber

text: Viber was originally launched as a VoIP application for voice calling. On 31 March 2011, Viber 2.0 was released which added instant messaging (IM) capabilities. In July 2012 group messaging and an [[HD Voice]] engine were added to both Android and iOS applications.Today, users can send several kinds of media files including photos, videos, GIFs, files, audio messages, and stickers.


title: Viber

text: In December 2012 Viber added '[[Sticker (messaging)|sticker]]s' to the application. In October 2013, Viber 4.0 was announced featuring a sticker 'market' where Viber would be selling stickers as a source of revenue.


title: Viber

text: In addition, version 4.0 introduced [[push-to-talk]] capabilities, and Viber Out, a feature that provides users the option to call mobile and landline numbers via VoIP without the need for the application.


title: Viber

text: Voice support was officially added for all [[Windows Phone 8]] devices on 2 April 2013. In September 2014, Viber 5.0 was released and introduced [[video calling]].


title: Viber

text: In November 2016, Viber version 6.5 launched Public Accounts to allow brands to engage in promotion and customer service on the platform, with initial partners including "[[The Huffington Post]]", [[Yandex]] and [[The Weather Channel]]. The app integrates with [[Customer relationship management|CRM software]] and offers [[chatbot]] [[Application programming interface|APIs]] for customer service. Viber Communities, an enhanced group chat feature, was introduced in February 2018. Group calling was introduced with version 10 in February 2019. Communities have an unlimited number of participants, compared to group chats that have a maximum of 250. Viber communities are protective of their users' privacy since neither superadmins nor admins can see members’ phone numbers. Also, members who enable private messages can contact each other while keeping their numbers hidden. In October 2020, Viber launched message statistics to go along with Community insights. These statistics offer Community admins the ability to see engagement levels with the content they post to their Communities.


title: Viber

text: Today, many different kinds of chatbots are also available on the app, including those providing essential information, quizzes, and more.


title: Autopsy

text: An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any disease or injury that may be present for research or educational purposes. (The term "necropsy" is generally reserved for non-human animals). Autopsies are usually performed by a specialized medical doctor called a pathologist. In most cases, a medical examiner or coroner can determine the cause of death. However, only a small portion of deaths require an autopsy to be performed, under certain circumstances.


title: Autopsy

text: Autopsies are performed for either legal or medical purposes. Autopsies can be performed when any of the following information is desired:


title: Autopsy

text: For example, a forensic autopsy is carried out when the cause of death may be a criminal matter, while a clinical or academic autopsy is performed to find the medical cause of death and is used in cases of unknown or uncertain death, or for research purposes. Autopsies can be further classified into cases where external examination suffices, and those where the body is dissected and internal examination is conducted. Permission from next of kin may be required for internal autopsy in some cases. Once an internal autopsy is complete, the body is reconstituted by sewing it back together.


title: Autopsy

text: The term "autopsy" derives from the Ancient Greek αὐτοψία "autopsia", "to see for oneself", derived from αὐτός ("autos", "oneself") and ὄψις ("opsis", "sight, view"). The word has been in use since around the 17th century.


title: Autopsy

text: The term "post-mortem" derives from the Latin "post", 'after', and "mortem", 'death'. It was first recorded in 1734.


title: Autopsy

text: The principal aims of an autopsy are to determine the cause of death, mode of death, manner of death, the state of health of the person before he or she died, and whether any medical diagnosis and treatment before death were appropriate.


title: Autopsy

text: In most Western countries the number of autopsies performed in hospitals has been decreasing every year since 1955. Critics, including pathologist and former "JAMA" editor George D. Lundberg, have charged that the reduction in autopsies is negatively affecting the care delivered in hospitals, because when mistakes result in death, they are often not investigated and lessons, therefore, remain unlearned.


title: Autopsy

text: When a person has permitted an autopsy in advance of their death, autopsies may also be carried out for the purposes of teaching or medical research.


title: Autopsy

text: An autopsy is frequently performed in cases of sudden death, where a doctor is not able to write a death certificate, or when death is believed to result from an unnatural cause. These examinations are performed under a legal authority (medical examiner, coroner , or procurator fiscal) and do not require the consent of relatives of the deceased. The most extreme example is the examination of murder victims, especially when medical examiners are looking for signs of death or the murder method, such as bullet wounds and exit points, signs of strangulation, or traces of poison.


title: Autopsy

text: Some religions including Judaism and Islam usually discourage the performing of autopsies on their adherents. Organizations such as ZAKA in Israel and Misaskim in the United States generally guide families on how to ensure that an unnecessary autopsy is not made.


title: Autopsy

text: Autopsies are used in clinical medicine to identify a medical error or a previously unnoticed condition that may endanger the living, such as infectious diseases or exposure to hazardous materials.


title: Autopsy

text: A study that focused on myocardial infarction (heart attack) as a cause of death found significant errors of omission and commission, i.e. a sizable number of cases ascribed to myocardial infarctions (MIs) were not MIs and a significant number of non-MIs were MIs.


title: Autopsy

text: A systematic review of studies of the autopsy calculated that in about 25% of autopsies, a major diagnostic error will be revealed. However, this rate has decreased over time and the study projects that in a contemporary US institution, 8.4% to 24.4% of autopsies will detect major diagnostic errors.


title: Autopsy

text: A large meta-analysis suggested that approximately one-third of death certificates are incorrect and that half of the autopsies performed produced findings that were not suspected before the person died. Also, it is thought that over one-fifth of unexpected findings can only be diagnosed histologically, "i.e.", by biopsy or autopsy, and that approximately one-quarter of unexpected findings, or 5% of all findings, are major and can similarly only be diagnosed from tissue.


title: Autopsy

text: One study found that (out of 694 diagnoses) "Autopsies revealed 171 missed diagnoses, including 21 cancers, 12 strokes, 11 myocardial infarctions, 10 pulmonary emboli, and 9 endocarditis, among others".


title: Autopsy

text: Focusing on intubated patients, one study found "abdominal pathologic conditions – abscesses, bowel perforations, or infarction – were as frequent as pulmonary emboli as a cause of class I errors. While patients with abdominal pathologic conditions generally complained of abdominal pain, results of an examination of the abdomen were considered unremarkable in most patients, and the symptom was not pursued".


title: Autopsy

text: Forensic science involves the application of the sciences to answer questions of interest to the legal system.


title: Autopsy

text: Medical examiners attempt to determine the time of death, the exact cause of death, and what, if anything, preceded the death, such as a struggle. A forensic autopsy may include obtaining biological specimens from the deceased for toxicological testing, including stomach contents. Toxicology tests may reveal the presence of one or more chemical "poisons" (all chemicals, in sufficient quantities, can be classified as a poison) and their quantity. Because post-mortem deterioration of the body, together with the gravitational pooling of bodily fluids, will necessarily alter the bodily environment, toxicology tests may overestimate, rather than underestimate, the quantity of the suspected chemical.


title: Autopsy

text: Following an in-depth examination of all the evidence, a medical examiner or coroner will assign a manner of death from the choices proscribed by the fact-finder's jurisdiction and will detail the evidence on the mechanism of the death.


title: Autopsy

text: Clinical autopsies serve two major purposes. They are performed to gain more insight into pathological processes and determine what factors contributed to a patient's death. For example, material for infectious disease testing can be collected during an autopsy. Autopsies are also performed to ensure the standard of care at hospitals. Autopsies can yield insight into how patient deaths can be prevented in the future.


title: Autopsy

text: Within the United Kingdom, clinical autopsies can be carried out only with the consent of the family of the deceased person, as opposed to a medico-legal autopsy instructed by a Coroner (England & Wales) or Procurator Fiscal (Scotland), to which the family cannot object.


title: Autopsy

text: Over time, autopsies have not only been able to determine the cause of death, but also lead to discoveries of various diseases such as fetal alcohol syndrome, Legionnaire's disease, and even viral hepatitis.


title: Autopsy

text: Academic autopsies are performed by students of anatomy for the purpose of study, giving medical students and residents firsthand experience viewing anatomy and pathology. Postmortem examinations require the skill to connect anatomic and clinical pathology together since they involve organ systems and interruptions from ante mortem and post mortem. These academic autopsies allow for students to practice and develop skills in pathology and become meticulous in later case examinations.


title: Autopsy

text: Virtual autopsies are performed using radiographic techniques which can be used in post-mortem examinations for a deceased individual. It is an alternative to medical autopsies, where radiographs are used, for example, Magnetic resonance imaging (MRI) and Computed tomography (CT scan) which produce radiographic images in order to determine the cause of death, the nature, and the manner of death, without dissecting the deceased. It can also be used in the identification of the deceased. This method is helpful in determining the questions pertaining to an autopsy without putting the examiner at risk of biohazardous materials that can be in an individual's body.


title: Autopsy

text: In 2004 in England and Wales, there were 514,000 deaths, of which 225,500 were referred to the coroner. Of those, 115,800 (22.5% of all deaths) resulted in post-mortem examinations and there were 28,300 inquests, 570 with a jury.


title: Autopsy

text: The rate of consented (hospital) autopsy in the UK and worldwide has declined rapidly over the past 50 years. In the UK in 2013 only 0.7% of inpatient adult deaths were followed by consented autopsy.


title: Autopsy

text: The autopsy rate in Germany is below 5% and thus much lower than in other countries in Europe. The governmental reimbursement is hardly sufficient to cover all the costs, so the medical journal Deutsches Ärzteblatt, issued by the German Medical Association makes the effort to raise awareness regarding the underfinancing of autopsies. The same sources stated that autopsy rates in Sweden and Finland reach 20 to 30%.


title: Autopsy

text: In the United States, autopsy rates fell from 17% in 1980 to 14% in 1985 and 11.5% in 1989, although the figures vary notably from county to county.


title: Autopsy

text: The body is received at a medical examiner's office, municipal mortuary, or hospital in a body bag or evidence sheet. A new body bag is used for each body to ensure that only evidence from that body is contained within the bag. Evidence sheets are an alternative way to transport the body. An evidence sheet is a sterile sheet that covers the body when it is moved. If it is believed there may be any significant evidence on the hands, for example, gunshot residue or skin under the fingernails, a separate paper sack is put around each hand and taped shut around the wrist.


title: Autopsy

text: There are two parts to the physical examination of the body: the external and internal examination. Toxicology, biochemical tests or genetic testing/molecular autopsy often supplement these and frequently assist the pathologist in assigning the cause or causes of death.


title: Autopsy

text: At many institutions, the person responsible for handling, cleaning, and moving the body is called a diener, the German word for "servant". In the UK this role is performed by an Anatomical Pathology Technician (APT), who will also assist the pathologist in eviscerating the body and reconstruction after the autopsy. After the body is received, it is first photographed. The examiner then notes the kind of clothes - if any - and their position on the body before they are removed. Next, any evidence such as residue, flakes of paint, or other material is collected from the external surfaces of the body. Ultraviolet light may also be used to search body surfaces for any evidence not easily visible to the naked eye. Samples of hair, nails , and the like are taken, and the body may also be radiographically imaged. Once the external evidence is collected, the body is removed from the bag, undressed, and any wounds present are examined. The body is then cleaned, weighed, and measured in preparation for the internal examination.


title: Autopsy

text: A general description of the body as regards ethnic group, sex, age, hair colour and length, eye colour , and other distinguishing features (birthmarks, old scar tissue, moles, tattoos, etc.) is then made. A voice recorder or a standard examination form is normally used to record this information.


title: Autopsy

text: In some countries , "e.g.", Scotland, France, Germany, Russia, and Canada, an autopsy may comprise an external examination only. This concept is sometimes termed a "view and grant". The principle behind this is that the medical records, history of the deceased and circumstances of death have all indicated as to the cause and manner of death without the need for an internal examination.


title: Autopsy

text: If not already in place, a plastic or rubber brick called a "head block" is placed under the shoulders of the corpse; hyperflexion of the neck makes the spine arch backward while stretching and pushing the chest upward to make it easier to incise. This gives the APT, or pathologist, maximum exposure to the trunk. After this is done, the internal examination begins. The internal examination consists of inspecting the internal organs of the body by dissection for evidence of trauma or other indications of the cause of death. For the internal examination there are a number of different approaches available:


title: Autopsy

text: There is no need for any incision to be made, which will be visible after completion of the examination when the deceased is dressed in a shroud.


title: Autopsy

text: In all of the above cases, the incision then extends all the way down to the pubic bone (making a deviation to either side of the navel) and avoiding, where possible, transecting any scars that may be present.


title: Autopsy

text: Bleeding from the cuts is minimal, or non-existent because the pull of gravity is producing the only blood pressure at this point, related directly to the complete lack of cardiac functionality. However, in certain cases, there is anecdotal evidence that bleeding can be quite profuse, especially in cases of drowning.


title: Autopsy

text: At this point, shears are used to open the chest cavity. The examiner uses the tool to cut through the ribs on the costal cartilage, to allow the sternum to be removed; this is done so that the heart and lungs can be seen in situ and that the heartin particular, the pericardial sacis not damaged or disturbed from opening. A PM 40 knife is used to remove the sternum from the soft tissue that attaches it to the mediastinum. Now the lungs and the heart are exposed. The sternum is set aside and will eventually be replaced at the end of the autopsy.


title: Autopsy

text: At this stage, the organs are exposed. Usually, the organs are removed in a systematic fashion. Making a decision as to what order the organs are to be removed will depend highly on the case in question. Organs can be removed in several ways: The first is the "en masse" technique of Letulle whereby all the organs are removed as one large mass. The second is the en bloc method of Ghon. The most popular in the UK is a modified version of this method, which is divided into four groups of organs. Although these are the two predominant evisceration techniques, in the UK variations on these are widespread.


title: Autopsy

text: One method is described here: The pericardial sac is opened to view the heart. Blood for chemical analysis may be removed from the inferior vena cava or the pulmonary veins. Before removing the heart, the pulmonary artery is opened in order to search for a blood clot. The heart can then be removed by cutting the inferior vena cava, the pulmonary veins, the aorta and pulmonary artery, and the superior vena cava. This method leaves the aortic arch intact, which will make things easier for the embalmer. The left lung is then easily accessible and can be removed by cutting the bronchus, artery, and vein at the hilum. The right lung can then be similarly removed. The abdominal organs can be removed one by one after first examining their relationships and vessels.


title: Autopsy

text: Most pathologists, however, prefer the organs to be removed all in one "block". Using dissection of the fascia, blunt dissection; using the fingers or hands and traction; the organs are dissected out in one piece for further inspection and sampling. During autopsies of infants, this method is used almost all of the time. The various organs are examined, weighed and tissue samples in the form of slices are taken. Even major blood vessels are cut open and inspected at this stage. Next the stomach and intestinal contents are examined and weighed. This could be useful to find the cause and time of death, due to the natural passage of food through the bowel during digestion. The more area empty, the longer the deceased had gone without a meal before death.


title: Autopsy

text: The body block that was used earlier to elevate the chest cavity is now used to elevate the head. To examine the brain, an incision is made from behind one ear, over the crown of the head, to a point behind the other ear. When the autopsy is completed, the incision can be neatly sewn up and is not noticed when the head is resting on a pillow in an open casket funeral. The scalp is pulled away from the skull in two flaps with the front flap going over the face and the rear flap over the back of the neck. The skull is then cut with a circular (or semicircular) bladed reciprocating saw to create a "cap" that can be pulled off, exposing the brain. The brain is then observed in situ. Then the brain's connection to the cranial nerves and spinal cord are severed, and the brain is lifted out of the skull for further examination. If the brain needs to be preserved before being inspected, it is contained in a large container of formalin (15 percent solution of formaldehyde gas in buffered water) for at least two, but preferably four weeks. This not only preserves the brain, but also makes it firmer, allowing easier handling without corrupting the tissue.


title: Autopsy

text: An important component of the autopsy is the reconstitution of the body such that it can be viewed, if desired, by relatives of the deceased following the procedure. After the examination, the body has an open and empty thoracic cavity with chest flaps open on both sides, the top of the skull is missing, and the skull flaps are pulled over the face and neck. It is unusual to examine the face, arms, hands or legs internally.


title: Autopsy

text: In the UK, following the Human Tissue Act 2004 all organs and tissue must be returned to the body unless permission is given by the family to retain any tissue for further investigation. Normally the internal body cavity is lined with cotton, wool, or a similar material, and the organs are then placed into a plastic bag to prevent leakage and are returned to the body cavity. The chest flaps are then closed and sewn back together and the skull cap is sewed back in place. Then the body may be wrapped in a shroud, and it is common for relatives to not be able to tell the procedure has been done when the body is viewed in a funeral parlor after embalming.


title: Autopsy

text: An autopsy of stroke may be able to establish the time taken from the onset of cerebral infarction to the time of death.


title: Autopsy

text: Around 3000 BCE, ancient Egyptians were one of the first civilizations to practice the removal and examination of the internal organs of humans in the religious practice of mummification.


title: Autopsy

text: Autopsies that opened the body to determine the cause of death were attested at least in the early third millennium BCE, although they were opposed in many ancient societies where it was believed that the outward disfigurement of dead persons prevented them from entering the afterlife (as with the Egyptians, who removed the organs through tiny slits in the body). Notable Greek autopsists were Erasistratus and Herophilus of Chalcedon, who lived in 3rd century BCE Alexandria, but in general, autopsies were rare in ancient Greece. In 44 BCE, Julius Caesar was the subject of an official autopsy after his murder by rival senators, the physician's report noting that the second stab wound Caesar received was the fatal one. Julius Caesar had been stabbed a total of 23 times. By around 150 BCE, ancient Roman legal practice had established clear parameters for autopsies. The greatest ancient anatomist was Galen (CE 129– ), whose findings would not be challenged until the Renaissance over a thousand years later.


title: Autopsy

text: The dissection of human remains for medical or scientific reasons continued to be practiced irregularly after the Romans, for instance by the Arab physicians Avenzoar and Ibn al-Nafis. In Europe they were done with enough regularity to become skilled, as early as 1200, and successful efforts to preserve the body, by filling the veins with wax and metals. Until the 20th century, it was thought that the modern autopsy process derived from the anatomists of the Renaissance. Giovanni Battista Morgagni (1682–1771), celebrated as the father of anatomical pathology, wrote the first exhaustive work on pathology, "De Sedibus et Causis Morborum per Anatomen Indagatis" (The Seats and Causes of Diseases Investigated by Anatomy, 1769).


title: Autopsy

text: In 1543, Andreas Vesalius conducted a public dissection of the body of a former criminal. He asserted and articulated the bones, this became the world's oldest surviving anatomical preparation. It is still displayed at the Anatomical Museum at the University of Basel.


title: Autopsy

text: In the mid-1800s, Carl von Rokitansky and colleagues at the Second Vienna Medical School began to undertake dissections as a means to improve diagnostic medicine.


title: Autopsy

text: The 19th-century medical researcher Rudolf Virchow, in response to a lack of standardization of autopsy procedures, established and published specific autopsy protocols (one such protocol still bears his name). He also developed the concept of pathological processes.


title: Autopsy

text: During the turn of the 20th century, the Scotland Yard created the Office of the Forensic Pathologist, a medical examiner trained in medicine, charged with investigating the cause of all unnatural deaths, including accidents, homicides, suicides, etc.


title: Autopsy

text: A post-mortem examination, or necropsy, is far more common in veterinary medicine than in human medicine. For many species that exhibit few external symptoms (sheep), or that are not suited to detail clinical examination (poultry, cage birds, zoo animals), it is a common method used by veterinary physicians to come to a diagnosis. A necropsy is mostly used like an autopsy to determine the cause of death. The entire body is examined at the gross visual level, and samples are collected for additional analyses.


title: Chief of Staff of the United States Army

text: The chief of staff of the Army (CSA) is a statutory position in the United States Army held by a general officer. As the highest-ranking officer assigned to serve in the Department of the Army, the chief is the principal military advisor and a deputy to the secretary of the Army. In a separate capacity, the CSA is a member of the Joint Chiefs of Staff () and, thereby, a military advisor to the National Security Council, the secretary of defense, and the president of the United States. The CSA is typically the highest-ranking officer on active duty in the U.S. Army unless the chairman or the vice chairman of the Joint Chiefs of Staff are Army officers.


text: The chief of staff of the Army is an administrative position based in the Pentagon. While the CSA does not have operational command authority over Army forces proper (which is within the purview of the Combatant Commanders who report to the Secretary of Defense), the CSA does exercise supervision of army units and organizations as the designee of the Secretary of the Army.


text: The chief of staff of the Army is nominated by for appointment by the president, for a four-year term of office, and must be confirmed by the Senate. The chief can be reappointed to serve one additional term, but only during times of war or national emergency declared by Congress. By statute, the chief is appointed as a four-star general.


text: The senior leadership of the Department of the Army consists of two civilians—the secretary of the Army (head of the department and subordinate to the secretary of defense) and the under secretary of the Army—and two military officers—the chief of staff of the Army and the vice chief of staff of the Army.


text: The chief reports directly to the secretary of the Army for army matters and assists in the Secretary's external affairs functions, including presenting and enforcing army policies, plans, and projections. The chief also directs the inspector general of the Army to perform inspections and investigations as required. In addition, the chief presides over the Army Staff and represents Army capabilities, requirements, policy, plans, and programs in Joint forums. Under delegation of authority made by the secretary of the Army, the chief designates army personnel and army resources to the commanders of the unified combatant commands. The chief performs all other functions enumerated in under the authority, direction, and control of the Secretary of the Army, or delegates those duties and responsibilities to other officers in his administration in his name. Like the other service counterparts, the chief has no operational command authority over army forces, dating back to the passage of the Department of Defense Reorganization Act of 1958. The chief is served by a number of Deputy Chiefs of Staff of the Army, such as G-1, Personnel. The chief's base pay is $21,147.30 per month and also received a Personal Money Allowance (Monthly Amount) of $333.33, a basic allowance for subsistence of $253.38, and a basic allowance for housing from $50.70 to $1923.30.


text: Until 1903, the senior military officer in the army was the Commanding General of the United States Army, who reported to the Secretary of War. From 1864 to 1865, Major General Henry Halleck (who had previously been Commanding General) served as "Chief of Staff of the Army" under the Commanding General, Lieutenant General Ulysses S. Grant, thus serving in a different office and not as the senior officer in the army.


title: NPC (meme)

text: NPC (; each letter separately; also known as the NPC Wojack), derived from "non-player character", is an internet meme that represents people who do not think for themselves or do not make their own decisions; those who lack intrapersonal communication.


title: NPC (meme)

text: The NPC meme, which graphically is based on the Wojak meme, was created in July 2016 by an anonymous author and first published on the imageboard 4chan, where the idea and inspiration behind the meme were introduced.


title: NPC (meme)

text: The NPC meme gained widespread attention and in October 2018 was covered in numerous news outlets, including "The New York Times", "The Verge", and the BBC. In 2022, the meme garnered popularity on video sharing service TikTok.


title: NPC (meme)

text: The concept of the NPC first appeared on 4chan in 2016. The post by an anonymous user who initiated the NPC meme, titled "Are you an NPC?", detailed the behavior of individuals acting similarly to non-player characters in video games by repeatedly using phrases such as "JUST BE YOURSELF", and ended the post with the following description of people the NPC meme intends to depict.


title: NPC (meme)

text: The design of the NPC meme character is based on Wojak (, ), a meme created in Microsoft Paint in 2010. Unlike the NPC meme, the Wojak meme (also known as Feels Guy) appeared first on the image hosting website vichan and has mainly been used for expression of feelings, most often melancholy or regret.


title: NPC (meme)

text: During the weeks leading up to the 2018 midterm elections in the United States, the NPC meme gained remarkable attention, with relatively high media coverage, publication of new NPC memes online, and several noticeable events. A large number of animated videos based on the NPC meme were uploaded to YouTube in the second half of October 2018, and Google searches for the term "NPC Wojak" peaked around the same time. In October 2018, a large number of Twitter accounts were created which presented themselves as NPCs, and more than 1,500 such accounts were subsequently banned by Twitter. In November, "InfoWars" held a competition promoting creation of NPC memes. The winning entry, by a Twitter user named "Carpe Donktum", was later retweeted by then-U.S. President Donald Trump on February 2019 before it was removed for copyright infringement. The re-election campaign for then-Iowa Representative Steve King also tweeted an NPC meme around the same time, aimed at the sitting Democratic members of Congress.


title: NPC (meme)

text: The number of searches for the search term "NPC Wojak" remained relatively constant during 2019, though at a level significantly lower than its peak from early October through mid November 2018.


title: NPC (meme)

text: Although the NPC meme was created 6 years after the Wojak meme, the NPC meme rapidly gained attention in comparison with the Wojak meme. On the website of the meme community "Know Your Meme", the NPC meme has 858,000 page views, 33 videos, 597 images and 749 comments as of December 31, 2019. This can be compared to the Wojak meme on which NPC is based, which has 787,000 page views, 6 videos, 332 images and 47 comments as of December 31, 2019. A Subreddit exclusively for "right wing, political" NPC memes without "extremist content" called r/NPCMemes was created on October 10, 2018.


title: NPC (meme)

text: In 2022, a variation of the NPC meme called "I Support The Current Thing" was popularized. According to "Slate", the meme is mainly used by the political right to mock liberals for "perceived conformism, frivolousness, and distractibility" who "blindly flit from news story to news story, issue to issue, changing their Facebook profile pics and Twitter display names to 'support' whatever 'Current Thing' dominates news and commentary. The current thing has been Ukraine, essential workers, the Women's March, Notre Dame after it caught on fire, etc." In March 2022, Elon Musk tweeted a version of the meme.


title: NPC (meme)

text: In appearance, the NPC character is gray in color, and usually short in stature simple in its design, with an expressionless face, a triangular nose and a blank stare. The shape of the NPC face resembles that of Wojak, and is drawn crudely.


title: NPC (meme)

text: The initial "NPC" refers to non-player character, a term used in video-games for characters the player cannot control. As such, a non-player character in a game is controlled by the computer, and typically interacts with the player through simple and repetitive actions, such as communicating the same sentence each time the player approaches the NPC. As such, NPCs have "no internality, agency, or capacity for critical thought", they rely on scripted lines and do not think by themselves. Following the analogy of non-player characters, the NPC meme is used to mock individuals the maker perceives as lacking those attributes, generally political opponents. The NPC responds using simple dialogue resembling video game NPCs, with no capability for discussion. Due to NPC memes' greater popularity among the political right, the NPC is generally portrayed as parroting left-wing positions. Despite being co-opted by right-wing movements to "mock leftists," both left- and right-wing NPC variants exist.


title: NPC (meme)

text: The NPC meme has been featured in major and minor news outlets alike, with frequent coverage during the peak of the NPCs popularity in fall 2018. According to "The Verge", a few articles (including one by "The New York Times" published on October 16, 2018) sparked a "domino effect" and led to increased spread of the meme on Twitter, YouTube and through articles.


title: NPC (meme)

text: In October 2018, users of r/The_Donald, a large subreddit that supported United States President Donald Trump, coordinated in creating accounts presented as NPCs on the American microblogging and social networking service Twitter. According to "The Week", the accounts spread "bland, politically correct messages intended to mimic and provoke liberal pronouncements". Following the mass creation of NPC Twitter accounts, the term "NPC" was used over 30,000 times on Twitter in a time span of 24 hours. Twitter responded to the event by banning more than 1,500 of its users presenting themselves as NPCs. The created accounts typically used profile pictures of NPC with slight modifications, such as colorful hair or partially covering masks. According to one or more anonymous sources quoted by "The Week" and "The New York Times", the users were banned for violating a term of use by Twitter against "intentionally misleading election-related content", ahead of the United States 2018 midterm election. The claim that NPC memes were used to spread misinformation about the 2018 United States midterm election is also reported by other news agencies, including "The Verge", "BBC" and "The Independent", although no examples are presented. The decision by Twitter to remove NPC accounts has upset many conservatives according to "BBC".


title: NPC (meme)

text: On January 13, 2019, the conservative street artist group "The Faction" modified a billboard featuring American comedian Bill Maher in West Hollywood using the NPC meme.


title: NPC (meme)

text: On February 19, 2019, a similar modification was performed on a billboard featuring English comedian John Oliver in Los Angeles, in which the face of Oliver was replaced by that of an NPC, and text ""Last Week Tonight with John Oliver"" was replaced by ""The Orange Man Bad Show with John Oliver"". The modified billboard also included the text "*MATRIX APPROVED NPC PROGRAMMING" and a speech balloon from the NPC containing words such as "CHEETOH" and "DRUMPH" with random symbols in green text, resembling the text shown in "The Matrix". According to "The Daily Dot", the modification of the billboard featuring Oliver, also credited to "The Faction", was an attempt to counteract the media's supposed "Trump derangement syndrome".


title: Turing completeness

text: In computability theory, a system of data-manipulation rules (such as a computer's instruction set, a programming language, or a cellular automaton) is said to be Turing-complete or computationally universal if it can be used to simulate any Turing machine (devised by English mathematician and computer scientist Alan Turing). This means that this system is able to recognize or decide other data-manipulation rule sets. Turing completeness is used as a way to express the power of such a data-manipulation rule set. Virtually all programming languages today are Turing-complete.


title: Turing completeness

text: A related concept is that of Turing equivalence two computers P and Q are called equivalent if P can simulate Q and Q can simulate P. The Church–Turing thesis conjectures that any function whose values can be computed by an algorithm can be computed by a Turing machine, and therefore that if any real-world computer can simulate a Turing machine, it is Turing equivalent to a Turing machine. A universal Turing machine can be used to simulate any Turing machine and by extension the computational aspects of any possible real-world computer.


title: Turing completeness

text: To show that something is Turing-complete, it is enough to show that it can be used to simulate some Turing-complete system. No physical system can have infinite memory, but if the limitation of finite memory is ignored, most programming languages are otherwise Turing-complete.


title: Turing completeness

text: In colloquial usage, the terms "Turing-complete" and "Turing-equivalent" are used to mean that any real-world general-purpose computer or computer language can approximately simulate the computational aspects of any other real-world general-purpose computer or computer language. In real life this leads to the practical concepts of computing virtualization and emulation.


title: Turing completeness

text: Real computers constructed so far can be functionally analyzed like a single-tape Turing machine (the "tape" corresponding to their memory); thus the associated mathematics can apply by abstracting their operation far enough. However, real computers have limited physical resources, so they are only linear bounded automaton complete. In contrast, a universal computer is defined as a device with a Turing-complete instruction set, infinite memory, and infinite available time.


title: Turing completeness

text: In computability theory, several closely related terms are used to describe the computational power of a computational system (such as an abstract machine or programming language):


title: Turing completeness

text: Turing completeness is significant in that every real-world design for a computing device can be simulated by a universal Turing machine. The Church–Turing thesis states that this is a law of mathematics that a universal Turing machine can, in principle, perform any calculation that any other programmable computer can. This says nothing about the effort needed to write the program, or the time it may take for the machine to perform the calculation, or any abilities the machine may possess that have nothing to do with computation.


title: Turing completeness

text: Charles Babbage's analytical engine (1830s) would have been the first Turing-complete machine if it had been built at the time it was designed. Babbage appreciated that the machine was capable of great feats of calculation, including primitive logical reasoning, but he did not appreciate that no other machine could do better. From the 1830s until the 1940s, mechanical calculating machines such as adders and multipliers were built and improved, but they could not perform a conditional branch and therefore were not Turing-complete.


title: Turing completeness

text: In the late 19th century, Leopold Kronecker formulated notions of computability, defining primitive recursive functions. These functions can be calculated by rote computation, but they are not enough to make a universal computer, because the instructions that compute them do not allow for an infinite loop. In the early 20th century, David Hilbert led a program to axiomatize all of mathematics with precise axioms and precise logical rules of deduction that could be performed by a machine. Soon it became clear that a small set of deduction rules are enough to produce the consequences of any set of axioms. These rules were proved by Kurt Gödel in 1930 to be enough to produce every theorem.


title: Turing completeness

text: The actual notion of computation was isolated soon after, starting with Gödel's incompleteness theorem. This theorem showed that axiom systems were limited when reasoning about the computation that deduces their theorems. Church and Turing independently demonstrated that Hilbert's (decision problem) was unsolvable, thus identifying the computational core of the incompleteness theorem. This work, along with Gödel's work on general recursive functions, established that there are sets of simple instructions, which, when put together, are able to produce any computation. The work of Gödel showed that the notion of computation is essentially unique.


title: Turing completeness

text: In 1941 Konrad Zuse completed the Z3 computer. Zuse was not familiar with Turing's work on computability at the time. In particular, the Z3 lacked dedicated facilities for a conditional jump, thereby precluding it from being Turing complete. However, in 1998, it was shown by Rojas that the Z3 is capable of simulating conditional jumps, and therefore Turing complete in theory. To do this, its tape program would have to be long enough to execute every possible path through both sides of every branch.


title: Turing completeness

text: The first computer capable of conditional branching in practice, and therefore Turing complete in practice, was the ENIAC in 1946. Zuse's Z4 computer was operational in 1945, but it did not support conditional branching until 1950.


title: Turing completeness

text: Computability theory uses models of computation to analyze problems and determine whether they are computable and under what circumstances. The first result of computability theory is that there exist problems for which it is impossible to predict what a (Turing-complete) system will do over an arbitrarily long time.


title: Turing completeness

text: The classic example is the halting problem: create an algorithm that takes as input a program in some Turing-complete language and some data to be fed to "that" program, and determines whether the program, operating on the input, will eventually stop or will continue forever. It is trivial to create an algorithm that can do this for "some" inputs, but impossible to do this in general. For any characteristic of the program's eventual output, it is impossible to determine whether this characteristic will hold.


title: Turing completeness

text: This impossibility poses problems when analyzing real-world computer programs. For example, one cannot write a tool that entirely protects programmers from writing infinite loops or protects users from supplying input that would cause infinite loops.


title: Turing completeness

text: One can instead limit a program to executing only for a fixed period of time (timeout) or limit the power of flow-control instructions (for example, providing only loops that iterate over the items of an existing array). However, another theorem shows that there are problems solvable by Turing-complete languages that cannot be solved by any language with only finite looping abilities (i.e., any language guaranteeing that every program will eventually finish to a halt). So any such language is not Turing-complete. For example, a language in which programs are guaranteed to complete and halt cannot compute the computable function produced by Cantor's diagonal argument on all computable functions in that language.


title: Turing completeness

text: A computer with access to an infinite tape of data may be more powerful than a Turing machine: for instance, the tape might contain the solution to the halting problem or some other Turing-undecidable problem. Such an infinite tape of data is called a Turing oracle. Even a Turing oracle with random data is not computable (with probability 1), since there are only countably many computations but uncountably many oracles. So a computer with a random Turing oracle can compute things that a Turing machine cannot.


title: Turing completeness

text: All known laws of physics have consequences that are computable by a series of approximations on a digital computer. A hypothesis called digital physics states that this is no accident because the universe itself is computable on a universal Turing machine. This would imply that no computer more powerful than a universal Turing machine can be built physically.


title: Turing completeness

text: The computational systems (algebras, calculi) that are discussed as Turing-complete systems are those intended for studying theoretical computer science. They are intended to be as simple as possible, so that it would be easier to understand the limits of computation. Here are a few:


title: Turing completeness

text: Most programming languages (their abstract models, maybe with some particular constructs that assume finite memory omitted), conventional and unconventional, are Turing-complete. This includes:


title: Turing completeness

text: Turing completeness is an abstract statement of ability, rather than a prescription of specific language features used to implement that ability. The features used to achieve Turing completeness can be quite different; Fortran systems would use loop constructs or possibly even goto statements to achieve repetition; Haskell and Prolog, lacking looping almost entirely, would use recursion. Most programming languages are describing computations on von Neumann architectures, which have memory (RAM and register) and a control unit. These two elements make this architecture Turing-complete. Even pure functional languages are Turing-complete.


title: Turing completeness

text: Turing completeness in declarative SQL is implemented through recursive common table expressions. Unsurprisingly, procedural extensions to SQL (PLSQL, etc.) are also Turing-complete. This illustrates one reason why relatively powerful non-Turing-complete languages are rare: the more powerful the language is initially, the more complex are the tasks to which it is applied and the sooner its lack of completeness becomes perceived as a drawback, encouraging its extension until it is Turing-complete.


title: Turing completeness

text: The untyped lambda calculus is Turing-complete, but many typed lambda calculi, including System F, are not. The value of typed systems is based in their ability to represent most typical computer programs while detecting more errors.


title: Turing completeness

text: Many computational languages exist that are not Turing-complete. One such example is the set of regular languages, which are generated by regular expressions and which are recognized by finite automata. A more powerful but still not Turing-complete extension of finite automata is the category of pushdown automata and context-free grammars, which are commonly used to generate parse trees in an initial stage of program compiling. Further examples include some of the early versions of the pixel shader languages embedded in Direct3D and OpenGL extensions.


title: Turing completeness

text: In total functional programming languages, such as Charity and Epigram, all functions are total and must terminate. Charity uses a type system and control constructs based on category theory, whereas Epigram uses dependent types. The LOOP language is designed so that it computes only the functions that are primitive recursive. All of these compute proper subsets of the total computable functions, since the full set of total computable functions is not computably enumerable. Also, since all functions in these languages are total, algorithms for recursively enumerable sets cannot be written in these languages, in contrast with Turing machines.


title: Machine gun

text: A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) are typically designed more for firing short bursts rather than continuous firepower, and are not considered true machine guns.


title: Machine gun

text: As a class of military kinetic projectile weapon, machine guns are designed to be mainly used as infantry support weapons and generally used when attached to a bipod or tripod, a fixed mount or a heavy weapons platform for stability against recoils. Many machine guns also use belt feeding and open bolt operation, features not normally found on other infantry firearms.


title: Machine gun

text: Machine guns can be further categorized as light machine guns, medium machine guns, heavy machine guns, general purpose machine guns and squad automatic weapons.


title: Machine gun

text: Similar automatic firearms of caliber or more are classified as autocannons, rather than machine guns.


title: Machine gun

text: Unlike semi-automatic firearms, which require one trigger pull per round fired, a machine gun is designed to continue firing for as long as the trigger is held down. Nowadays, the term is restricted to relatively heavy crew-served weapons, able to provide continuous or frequent bursts of automatic fire for as long as ammunition feeding is replete. Machine guns are used against infantry, low-flying aircraft, small boats and lightly/unarmored land vehicles, and can provide suppressive fire (either directly or indirectly) or enforce area denial over a sector of land with grazing fire. They are commonly mounted on fast attack vehicles such as technicals to provide heavy mobile firepower, armored vehicles such as tanks for engaging targets too small to justify the use of the primary weaponry or too fast to effectively engage with it, and on aircraft as defensive armament or for strafing ground targets, though on fighter aircraft true machine guns have mostly been supplanted by large-caliber rotary guns.


title: Machine gun

text: Some machine guns have in practice sustained fire almost continuously for hours; other automatic weapons overheat after less than a minute of use. Because they become very hot, the great majority of designs fire from an open bolt, to permit air cooling from the breech between bursts. They also usually have either a barrel cooling system, slow-heating heavyweight barrel, or removable barrels which allow a hot barrel to be replaced.


title: Machine gun

text: Although subdivided into "light", "medium", "heavy" or "general-purpose", even the lightest machine guns tend to be substantially larger and heavier than standard infantry arms. Medium and heavy machine guns are either mounted on a tripod or on a vehicle; when carried on foot, the machine gun and associated equipment (tripod, ammunition, spare barrels) require additional crew members.


title: Machine gun

text: Light machine guns are designed to provide mobile fire support to a squad and are typically air-cooled weapons fitted with a box magazine or drum and a bipod; they may use full-size rifle rounds, but modern examples often use intermediate rounds. Medium machine guns use full-sized rifle rounds and are designed to be used from fixed positions mounted on a tripod. The heavy machine gun is a term originating in World War I to describe heavyweight medium machine guns and persisted into World War II with Japanese Hotchkiss M1914 clones; today, however, it is used to refer to automatic weapons with a caliber of at least but less than 20 mm. A general-purpose machine gun is usually a lightweight medium machine gun that can either be used with a bipod and drum in the light machine gun role or a tripod and belt feed in the medium machine gun role.


title: Machine gun

text: Machine guns usually have simple iron sights, though the use of optics is becoming more common. A common aiming system for direct fire is to alternate solid ("ball") rounds and tracer ammunition rounds (usually one tracer round for every four ball rounds), so shooters can see the trajectory and "walk" the fire into the target, and direct the fire of other soldiers.


title: Machine gun

text: Many heavy machine guns, such as the Browning M2 .50 caliber machine gun, are accurate enough to engage targets at great distances. During the Vietnam War, Carlos Hathcock set the record for a long-distance shot at with a .50 caliber heavy machine gun he had equipped with a telescopic sight. This led to the introduction of .50 caliber anti-materiel sniper rifles, such as the Barrett M82.


title: Machine gun

text: Other automatic weapons are subdivided into several categories based on the size of the bullet used, whether the cartridge is fired from a closed bolt or an open bolt, and whether the action used is locked or is some form of blowback.


title: Machine gun

text: Fully automatic firearms using pistol-caliber ammunition are called machine pistols or submachine guns largely on the basis of size; those using shotgun cartridges are almost always referred to as automatic shotguns. The term personal defense weapon (PDW) is sometimes applied to weapons firing dedicated armor-piercing rounds which would otherwise be regarded as machine pistols or SMGs, but it is not particularly strongly defined and has historically been used to describe a range of weapons from ordinary SMGs to compact assault rifles. Selective fire rifles firing a full-power rifle cartridge from a closed bolt are called automatic rifles or battle rifles, while rifles that fire an intermediate cartridge are called assault rifles.


title: Machine gun

text: Assault rifles are a compromise between the size and weight of a pistol-caliber submachine gun and a full-size battle rifle, firing intermediate cartridges and allowing semi-automatic and burst or full-automatic fire options (selective fire), sometimes with both of the latter presents.


title: Machine gun

text: The operation is basically the same for all locked breech automatic firearms, regardless of the means of activating these mechanisms. There are also multi-chambered formats, such as revolver cannon, and some types, such as the Schwarzlose machine gun etc., that do not lock the breech but instead use some type of delayed blowback.


title: Machine gun

text: Most modern machine guns are of the locking type, and of these, most utilize the principle of gas-operated reloading, which taps off some of the propellant gas from the fired cartridge, using its mechanical pressure to unlock the bolt and cycle the action. The first of these was invented by the French brothers Claire, who patented a gas operated rifle, which included a gas cylinder, in 1892. The Russian PK machine gun is a more modern example. Another efficient and widely used format is the recoil actuated type, which uses the gun's recoil energy for the same purpose. Machine guns such as the M2 Browning and MG42, are of this second kind. A cam, lever or actuator absorbs part of the energy of the recoil to operate the gun mechanism.


title: Machine gun

text: An externally actuated weapon uses an external power source, such as an electric motor or hand crank, to move its mechanism through the firing sequence. Modern weapons of this type are often referred to as Gatling guns, after the original inventor (not only of the well-known hand-cranked 19th century proto-machine gun, but also of the first electrically powered version). They have several barrels each with an associated chamber and action on a rotating carousel and a system of cams that load, cock, and fire each mechanism progressively as it rotates through the sequence; essentially each barrel is a separate bolt-action rifle using a common feed source. The continuous nature of the rotary action, and its relative immunity to overheating allow for a very high cyclic rate of fire, often several thousand rounds per minute. Rotary guns are less prone to jamming than a gun operated by gas or recoil, as the external power source will eject misfired rounds with no further trouble, but this is not possible in the rare cases of self-powered rotary guns. Rotary designs are intrinsically comparatively bulky and expensive, and are therefore generally used with large rounds, 20 mm in diameter or more, often referred to as Rotary cannon – though the rifle-calibre Minigun is an exception to this. Whereas such weapons are highly reliable and formidably effective, one drawback is that the weight and size of the power source and driving mechanism makes them usually impractical for use outside of a vehicle or aircraft mount.


title: Machine gun

text: Revolver cannons, such as the Mauser MK 213, were developed in World War II by the Germans to provide high-caliber cannons with a reasonable rate of fire and reliability. In contrast to the rotary format, such weapons have a single barrel and a recoil-operated carriage holding a revolving chamber with typically five chambers. As each round is fired, electrically, the carriage moves back rotating the chamber which also ejects the spent case, indexes the next live round to be fired with the barrel and loads the next round into the chamber. The action is very similar to that of the revolver pistols common in the 19th and 20th centuries, giving this type of weapon its name. A Chain gun is a specific, patented type of Revolver cannon, the name, in this case, deriving from its driving mechanism.


title: Machine gun

text: As noted above, firing a machine gun for prolonged periods produces large amounts of heat. In a worst-case scenario, this may cause a cartridge to overheat and detonate even when the trigger is not pulled, potentially leading to damage or causing the gun to cycle its action and keep firing until it has exhausted its ammunition supply or jammed; this is known as "cooking off" ( as distinct from "runaway fire" where the sear fails to re-engage when the trigger is released). To guard against cook-offs occurring, some kind of cooling system or design element is required. Early machine guns were often water-cooled and while this technology was very effective, (and was indeed one of the sources of the notorious efficiency of machine guns during the First World War ), the water jackets also added considerable weight to an already bulky design; they were also vulnerable to the enemies' bullets themselves. Armour could be provided, and in WW I the Germans in particular often did this; but this added yet more weight to the guns. Air-cooled machine guns often feature quick-change barrels (often carried by a crew member), passive cooling fins, or in some designs forced-air cooling, such as that employed by the Lewis Gun. Advances in metallurgy and the use of special composites in barrel liners have allowed for greater heat absorption and dissipation during firing. The higher the rate of fire, the more often barrels must be changed and allowed to cool. To minimize this, most air-cooled guns are fired only in short bursts or at a reduced rate of fire. Some designs – such as the many variants of the MG42 – are capable of rates of fire in excess of 1,200 rounds per minute. Motorized Gatling guns are capable of the fastest firing rates of all, partly because this format involves extra energy being injected into the system from outside, instead of depending on energy derived from the propellant contained within the cartridges, partly because the next round can be inserted simultaneously with or before the ejection of the previous cartridge case, and partly because this design intrinsically deals with the unwanted heat very efficiently – effectively quick-changing the barrel and chamber after every shot. The multiple guns that comprise a Gatling being a much larger bulk of metal than other, single-barreled guns, they are thus much slower to rise in temperature for a given amount of heat, while at the same time they are also much better at shedding the excess, as the extra barrels provide a larger surface area from which to dissipate the unwanted thermal energy. In addition to that, they are in the nature of the design spun at very high speed during rapid fire, which has the benefit of producing enhanced air-cooling as a side-effect.