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  • 21 Aug, 2019

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Portal:Science

Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into two or three major branches: the natural sciences (e.g., physics, chemistry, and biology), which study the physical world; and the behavioural sciences (e.g., economics, psychology, and sociology), which study individuals and societies. The formal sciences (e.g., logic, mathematics, and theoretical computer science), which study formal systems governed by axioms and rules, are sometimes described as being sciences as well; however, they are often regarded as a separate field because they rely on deductive reasoning instead of the scientific method or empirical evidence as their main methodology. Applied sciences are disciplines that use scientific knowledge for practical purposes, such as engineering and medicine. (Full article...)

  Featured articles are displayed here, which represent some of the best content on English Wikipedia.

  • Image 2 Givati Parking Lot dig The Acra (also spelled Akra, from Ancient Greek: Ἄκρα, Hebrew: חקרא ,חקרה Ḥaqra(h)), with the meaning of "stronghold" (see under "Etymology"), was a place in Jerusalem thought to have had a fortified compound built by Antiochus Epiphanes, ruler of the Seleucid Empire, following his sack of the city in 168 BCE. The name Acra was also used at a later time for a city quarter probably associated with the by-then destroyed fortress, known in his time to Josephus (1st century CE) as both Acra and "the lower city". The fortress played a significant role in the events surrounding the Maccabean Revolt, which resulted in the formation of the Hasmonean Kingdom. The "upper city" was captured by Judas Maccabeus, with the Seleucid garrison taking refuge in the "Acra" below, and the task of destroying this last enemy stronghold inside Jerusalem fell to Simon Maccabeus surnamed Thassi. Knowledge about the Acra is based almost exclusively on the writings of Josephus, which are of a later date, and on the First and Second Books of Maccabees, which were written not long after the described events. (Full article...)

    The Acra (also spelled Akra, from Ancient Greek: Ἄκρα, Hebrew: חקרא ,חקרה Ḥaqra(h)), with the meaning of "stronghold" (see under "Etymology"), was a place in Jerusalem thought to have had a fortified compound built by Antiochus Epiphanes, ruler of the Seleucid Empire, following his sack of the city in 168 BCE. The name Acra was also used at a later time for a city quarter probably associated with the by-then destroyed fortress, known in his time to Josephus (1st century CE) as both Acra and "the lower city". The fortress played a significant role in the events surrounding the Maccabean Revolt, which resulted in the formation of the Hasmonean Kingdom. The "upper city" was captured by Judas Maccabeus, with the Seleucid garrison taking refuge in the "Acra" below, and the task of destroying this last enemy stronghold inside Jerusalem fell to Simon Maccabeus surnamed Thassi. Knowledge about the Acra is based almost exclusively on the writings of Josephus, which are of a later date, and on the First and Second Books of Maccabees, which were written not long after the described events. (Full article...)
  • Image 3 Russula virescens is a basidiomycete mushroom of the genus Russula, and is commonly known as the green-cracking russula, the quilted green russula, or the green brittlegill. It can be recognized by its distinctive pale green cap that measures up to 15 cm (6 in) in diameter, the surface of which is covered with darker green angular patches. It has crowded white gills, and a firm, white stipe that is up to 8 cm (3 in) tall and 4 cm (1.6 in) thick. Considered to be one of the best edible mushrooms of the genus Russula, it is especially popular in Spain and China. With a taste that is described variously as mild, nutty, fruity, or sweet, it is cooked by grilling, frying, sautéeing, or eaten raw. Mushrooms are rich in carbohydrates and proteins, with a low fat content. (Full article...)

    Russula virescens is a basidiomycete mushroom of the genus Russula, and is commonly known as the green-cracking russula, the quilted green russula, or the green brittlegill. It can be recognized by its distinctive pale green cap that measures up to 15 cm (6 in) in diameter, the surface of which is covered with darker green angular patches. It has crowded white gills, and a firm, white stipe that is up to 8 cm (3 in) tall and 4 cm (1.6 in) thick. Considered to be one of the best edible mushrooms of the genus Russula, it is especially popular in Spain and China. With a taste that is described variously as mild, nutty, fruity, or sweet, it is cooked by grilling, frying, sautéeing, or eaten raw. Mushrooms are rich in carbohydrates and proteins, with a low fat content. (Full article...)
  • Image 4 At Margaret River Banksia attenuata, commonly known as the candlestick banksia, slender banksia, or biara to the Noongar people, is a species of plant in the family Proteaceae. Commonly a tree, it reaches 10 m (33 ft) high, but it is often a shrub in drier areas 0.4 to 2 m (1.3 to 6.6 ft) high. It has long, narrow, serrated leaves and bright yellow inflorescences, or flower spikes, held above the foliage, which appear in spring and summer. The flower spikes age to grey and swell with the development of the woody follicles. The candlestick banksia is found across much of the southwest of Western Australia, from north of Kalbarri National Park down to Cape Leeuwin and across to Fitzgerald River National Park. (Full article...)

    Banksia attenuata, commonly known as the candlestick banksia, slender banksia, or biara to the Noongar people, is a species of plant in the family Proteaceae. Commonly a tree, it reaches 10 m (33 ft) high, but it is often a shrub in drier areas 0.4 to 2 m (1.3 to 6.6 ft) high. It has long, narrow, serrated leaves and bright yellow inflorescences, or flower spikes, held above the foliage, which appear in spring and summer. The flower spikes age to grey and swell with the development of the woody follicles. The candlestick banksia is found across much of the southwest of Western Australia, from north of Kalbarri National Park down to Cape Leeuwin and across to Fitzgerald River National Park. (Full article...)
  • Image 5 Promotional poster Gertie the Dinosaur is a 1914 animated short film by American cartoonist and animator Winsor McCay. It is the earliest animated film to feature a dinosaur. McCay first used the film before live audiences as an interactive part of his vaudeville act; the frisky, childlike Gertie did tricks at the command of her master. McCay's employer William Randolph Hearst curtailed McCay's vaudeville activities, so McCay added a live-action introductory sequence to the film for its theatrical release renamed Winsor McCay, the Famous Cartoonist, and Gertie. McCay abandoned a sequel, Gertie on Tour (c. 1921), after producing about a minute of footage. (Full article...)

    Gertie the Dinosaur is a 1914 animated short film by American cartoonist and animator Winsor McCay. It is the earliest animated film to feature a dinosaur. McCay first used the film before live audiences as an interactive part of his vaudeville act; the frisky, childlike Gertie did tricks at the command of her master. McCay's employer William Randolph Hearst curtailed McCay's vaudeville activities, so McCay added a live-action introductory sequence to the film for its theatrical release renamed Winsor McCay, the Famous Cartoonist, and Gertie. McCay abandoned a sequel, Gertie on Tour (c. 1921), after producing about a minute of footage. (Full article...)
  • Image 6 Illustration by Allan Brooks The Zapata rail (Mustelirallus cerverai) is a medium-sized, dark-coloured rail. It has brown upperparts, greyish-blue underparts, a red-based yellow bill, white undertail coverts, and red eyes and legs. Its short wings render it almost flightless. It is endemic to the wetlands of the Zapata Peninsula in southern Cuba, where its only known nest was found in sawgrass tussocks. Little is known of its diet or reproductive behaviour, and its described calls may belong to a different species. (Full article...)

    The Zapata rail (Mustelirallus cerverai) is a medium-sized, dark-coloured rail. It has brown upperparts, greyish-blue underparts, a red-based yellow bill, white undertail coverts, and red eyes and legs. Its short wings render it almost flightless. It is endemic to the wetlands of the Zapata Peninsula in southern Cuba, where its only known nest was found in sawgrass tussocks. Little is known of its diet or reproductive behaviour, and its described calls may belong to a different species. (Full article...)
  • Image 7 Portrait by Nadar, c. 1888 Dona Teresa Cristina (14 March 1822 – 28 December 1889), nicknamed "the Mother of the Brazilians", was Empress of Brazil as the consort of Emperor Dom Pedro II from their marriage on 30 May 1843 until 15 November 1889, when the monarchy was abolished. Born a princess of the Kingdom of the Two Sicilies in present-day southern Italy, Teresa Cristina was the daughter of King Don Francesco I (Francis I) of the Italian branch of the House of Bourbon and his wife Maria Isabel (Maria Isabella). It was long believed by historians that the Princess was raised in an ultra-conservative, intolerant atmosphere which resulted in a timid and unassertive character in public and an ability to be contented with very little materially or emotionally. Recent studies revealed a more complex character, who despite having respected the social norms of the era, was able to assert a limited independence due to her strongly opinionated personality as well as her interest in learning, sciences and culture. (Full article...)

    Dona Teresa Cristina (14 March 1822 – 28 December 1889), nicknamed "the Mother of the Brazilians", was Empress of Brazil as the consort of Emperor Dom Pedro II from their marriage on 30 May 1843 until 15 November 1889, when the monarchy was abolished. Born a princess of the Kingdom of the Two Sicilies in present-day southern Italy, Teresa Cristina was the daughter of King Don Francesco I (Francis I) of the Italian branch of the House of Bourbon and his wife Maria Isabel (Maria Isabella). It was long believed by historians that the Princess was raised in an ultra-conservative, intolerant atmosphere which resulted in a timid and unassertive character in public and an ability to be contented with very little materially or emotionally. Recent studies revealed a more complex character, who despite having respected the social norms of the era, was able to assert a limited independence due to her strongly opinionated personality as well as her interest in learning, sciences and culture. (Full article...)
  • Image 8 The orca (Orcinus orca), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. It is the only extant species in the genus Orcinus and is recognizable by its black-and-white patterned body. A cosmopolitan species, they are found in diverse marine environments, from Arctic to Antarctic regions to tropical seas. (Full article...)

    The orca (Orcinus orca), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. It is the only extant species in the genus Orcinus and is recognizable by its black-and-white patterned body. A cosmopolitan species, they are found in diverse marine environments, from Arctic to Antarctic regions to tropical seas. (Full article...)
  • Image 9 Reconstructed skeleton in Japan Deinocheirus (/ˌdaɪnoʊˈkaɪrəs/ DY-no-KY-rəs) is a genus of large ornithomimosaur that lived during the Late Cretaceous around 70 million years ago. In 1965, a pair of large arms, shoulder girdles, and a few other bones of a new dinosaur were first discovered in the Nemegt Formation of Mongolia. In 1970, this specimen became the holotype of the only species within the genus, Deinocheirus mirificus; the genus name is Greek for "horrible hand". No further remains were discovered for almost fifty years, and its nature remained a mystery. Two more complete specimens were described in 2014, which shed light on many aspects of the animal. Parts of these new specimens had been looted from Mongolia some years before, but were repatriated in 2014. (Full article...)

    Deinocheirus (/ˌdnˈkrəs/ DY-no-KY-rəs) is a genus of large ornithomimosaur that lived during the Late Cretaceous around 70 million years ago. In 1965, a pair of large arms, shoulder girdles, and a few other bones of a new dinosaur were first discovered in the Nemegt Formation of Mongolia. In 1970, this specimen became the holotype of the only species within the genus, Deinocheirus mirificus; the genus name is Greek for "horrible hand". No further remains were discovered for almost fifty years, and its nature remained a mystery. Two more complete specimens were described in 2014, which shed light on many aspects of the animal. Parts of these new specimens had been looted from Mongolia some years before, but were repatriated in 2014. (Full article...)
  • Image 10 Reconstructed T. sethi skeleton (the postcranium is hypothetical) with Anhanguera behind, National Museum of Nature and Science, Tokyo Thalassodromeus is a genus of pterosaur that lived in what is now Brazil during the Early Cretaceous period, about a hundred million years ago. The original skull, discovered in 1983 in the Araripe Basin of northeastern Brazil, was collected in several pieces. In 2002, the skull was made the holotype specimen of Thalassodromeus sethi by palaeontologists Alexander Kellner and Diogenes de Almeida Campos. The generic name means "sea runner" (in reference to its supposed mode of feeding), and the specific name refers to the Egyptian god Seth due to its crest being supposedly reminiscent of Seth's crown. Other scholars have pointed out that the crest was instead similar to the crown of Amon. A jaw tip was assigned to T. sethi in 2005, became the basis of the new genus Banguela in 2015, and assigned back to Thalassodromeus as the species T. oberlii in 2018, though other researchers consider it a valid genus. Another species (T. sebesensis) was described in 2015 based on a supposed crest fragment, but this was later shown to be part of a turtle shell. (Full article...)

    Thalassodromeus is a genus of pterosaur that lived in what is now Brazil during the Early Cretaceous period, about a hundred million years ago. The original skull, discovered in 1983 in the Araripe Basin of northeastern Brazil, was collected in several pieces. In 2002, the skull was made the holotype specimen of Thalassodromeus sethi by palaeontologists Alexander Kellner and Diogenes de Almeida Campos. The generic name means "sea runner" (in reference to its supposed mode of feeding), and the specific name refers to the Egyptian god Seth due to its crest being supposedly reminiscent of Seth's crown. Other scholars have pointed out that the crest was instead similar to the crown of Amon. A jaw tip was assigned to T. sethi in 2005, became the basis of the new genus Banguela in 2015, and assigned back to Thalassodromeus as the species T. oberlii in 2018, though other researchers consider it a valid genus. Another species (T. sebesensis) was described in 2015 based on a supposed crest fragment, but this was later shown to be part of a turtle shell. (Full article...)
  • Image 11 Inflorescence with unopened buds (left), opened flowers (right) Banksia marginata, commonly known as the silver banksia, is a species of tree or woody shrub in the family Proteaceae found throughout much of southeastern Australia. It ranges from the Eyre Peninsula in South Australia to north of Armidale, New South Wales, and across Tasmania and the islands of Bass Strait. It grows in various habitats, including Eucalyptus forest, scrub, heathland and moorland. Banksia marginata varies widely in habit, ranging from a 20-centimetre (7.9 in) shrub to a 12-metre (40 ft) tree. The narrow leaves are linear and the yellow inflorescences occur from late summer to early winter. These flower spikes fade to brown and then grey and develop woody follicles bearing the winged seeds. Originally described by Antonio José Cavanilles in 1800, further collections of B. marginata were designated as several separate species by Robert Brown in 1810. However, all were reclassified as a single species by George Bentham in 1870. No distinct subspecies have been recognised by Banksia expert Alex George, who nonetheless concedes that further work is needed. (Full article...)

    Banksia marginata, commonly known as the silver banksia, is a species of tree or woody shrub in the family Proteaceae found throughout much of southeastern Australia. It ranges from the Eyre Peninsula in South Australia to north of Armidale, New South Wales, and across Tasmania and the islands of Bass Strait. It grows in various habitats, including Eucalyptus forest, scrub, heathland and moorland. Banksia marginata varies widely in habit, ranging from a 20-centimetre (7.9 in) shrub to a 12-metre (40 ft) tree. The narrow leaves are linear and the yellow inflorescences occur from late summer to early winter. These flower spikes fade to brown and then grey and develop woody follicles bearing the winged seeds. Originally described by Antonio José Cavanilles in 1800, further collections of B. marginata were designated as several separate species by Robert Brown in 1810. However, all were reclassified as a single species by George Bentham in 1870. No distinct subspecies have been recognised by Banksia expert Alex George, who nonetheless concedes that further work is needed. (Full article...)
  • Image 12 Thunder II and Ann Judge Thunder is the stage name for the horse who is the official live animal mascot for the Denver Broncos football team. Thunder shares mascot duties with Miles, a human who wears a horse head mask atop a Broncos uniform. (Full article...)

    Thunder is the stage name for the horse who is the official live animal mascot for the Denver Broncos football team. Thunder shares mascot duties with Miles, a human who wears a horse head mask atop a Broncos uniform. (Full article...)
  • Image 13 Mobula alfredi at Dharavandhoo, Maldives Manta rays are large rays belonging to the genus Mobula (formerly its own genus Manta). The larger species, M. birostris, reaches 7 m (23 ft) in width, while the smaller, M. alfredi, reaches 5.5 m (18 ft). Both have triangular pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Myliobatiformes (stingrays and relatives) and are placed in the family Myliobatidae (eagle rays). They have the largest brains and brain to body ratio of all fish, and can pass the mirror test. (Full article...)

    Manta rays are large rays belonging to the genus Mobula (formerly its own genus Manta). The larger species, M. birostris, reaches 7 m (23 ft) in width, while the smaller, M. alfredi, reaches 5.5 m (18 ft). Both have triangular pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Myliobatiformes (stingrays and relatives) and are placed in the family Myliobatidae (eagle rays). They have the largest brains and brain to body ratio of all fish, and can pass the mirror test. (Full article...)
  • Image 14 False-color image of aurorae on the north pole of Jupiter, as viewed by the Hubble Space Telescope The magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973. (Full article...)

    The magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973. (Full article...)
  • Image 15 Transandinomys is a genus of rodents in the tribe Oryzomyini of family Cricetidae. It includes two species—T. bolivaris and T. talamancae—found in forests from Honduras in Central America south and east to southwestern Ecuador and northwestern Venezuela in northern South America. Until 2006, its members were included in the genus Oryzomys, but phylogenetic analysis showed that they are not closely related to the type species of that genus, and they have therefore been placed in a new genus. They may be most closely related to genera like Hylaeamys and Euryoryzomys, which contain very similar species. Both species of Transandinomys have had eventful taxonomic histories. (Full article...)

    Transandinomys is a genus of rodents in the tribe Oryzomyini of family Cricetidae. It includes two species—T. bolivaris and T. talamancae—found in forests from Honduras in Central America south and east to southwestern Ecuador and northwestern Venezuela in northern South America. Until 2006, its members were included in the genus Oryzomys, but phylogenetic analysis showed that they are not closely related to the type species of that genus, and they have therefore been placed in a new genus. They may be most closely related to genera like Hylaeamys and Euryoryzomys, which contain very similar species. Both species of Transandinomys have had eventful taxonomic histories. (Full article...)
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    Language is a structured system of communication that consists of grammar and vocabulary. It is the primary means by which humans convey meaning, both in spoken and signed forms, and may also be conveyed through writing. Human language is characterized by its cultural and historical diversity, with significant variations observed between cultures and across time. Human languages possess the properties of productivity and displacement, which enable the creation of an infinite number of sentences, and the ability to refer to objects, events, and ideas that are not immediately present in the discourse. The use of human language relies on social convention and is acquired through learning. (Full article...)

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    Science things you can do
    Many naturally occurring phenomena approximate a normal distribution.
    Many naturally occurring phenomena approximate a normal distribution.
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    Science News

    5 November 2024 –
    Researchers at Kyoto University in Japan launch LignoSat, the world's first wooden satellite constructed without screws or glue, into space. It will orbit Earth for six months. (DW)
    10 October 2024 –
    In its annual Living Planet report, the World Wildlife Fund estimates that wild populations of animal species have decreased over 70% since 1970, with some high-biodiversity areas seeing up to 95% declines. (DW)
    10 October 2024 – Tomb of Christopher Columbus
    Researchers from the University of Granada confirm that bones lying in the Seville Cathedral in Seville, Andalusia, Spain, belonged to Christopher Columbus. (ABC Spain)
    9 October 2024 – Nobel Prize in Chemistry
    This year's Nobel Prize in Chemistry is jointly awarded to British computer scientist Demis Hassabis and American chemist John M. Jumper for their work on protein structure prediction, and to American biochemist and computational biologist David Baker for his work on computational protein design. (The New York Times) (Nobel Prize)
    8 October 2024 – Nobel Prize in Physics
    American physicist John Hopfield and British-Canadian computer scientist Geoffrey Hinton are awarded this year's Nobel Prize in Physics "for foundational discoveries and inventions that enable machine learning with artificial neural networks". (The Guardian)
    24 September 2024 –
    Scientists from the University of Waterloo announce that they have positively identified bones found on King William Island in Nunavut, Canada, as those of James Fitzjames, captain of HMS Erebus during Franklin's lost expedition. (CBC News)
    This following Science-related articles is a most visited articles of WikiProject Science, See complete list at Wikipedia:WikiProject Science/Popular pages.

  • Image 2 Artificial intelligence (AI), in its broadest sense, is intelligence exhibited by machines, particularly computer systems. It is a field of research in computer science that develops and studies methods and software that enable machines to perceive their environment and use learning and intelligence to take actions that maximize their chances of achieving defined goals. Such machines may be called AIs. (Full article...)
    Artificial intelligence (AI), in its broadest sense, is intelligence exhibited by machines, particularly computer systems. It is a field of research in computer science that develops and studies methods and software that enable machines to perceive their environment and use learning and intelligence to take actions that maximize their chances of achieving defined goals. Such machines may be called AIs. (Full article...)
  • Image 3 Sci-Hub is a shadow library website that provides free access to millions of research papers, regardless of copyright, by bypassing publishers' paywalls in various ways. Unlike Library Genesis, it does not provide access to books. Sci-Hub was founded in Kazakhstan by Alexandra Elbakyan in 2011, in response to the high cost of research papers behind paywalls (see Serials crisis). The site is extensively used worldwide. In September 2019, the site's operator(s) said that it served approximately 400,000 requests per day. In addition to its intensive use, Sci-Hub stands out among other shadow libraries because of its easy use/reliability and because of the enormous size of its collection; a 2018 study estimated that Sci-Hub provided access to most of the scholarly publications with issued DOI numbers. On 15 July 2022, Sci-Hub reported that its collection comprised 88,343,822 files. Since December 2020, the site has paused uploads due to legal troubles. (Full article...)
    Sci-Hub is a shadow library website that provides free access to millions of research papers, regardless of copyright, by bypassing publishers' paywalls in various ways. Unlike Library Genesis, it does not provide access to books. Sci-Hub was founded in Kazakhstan by Alexandra Elbakyan in 2011, in response to the high cost of research papers behind paywalls (see Serials crisis). The site is extensively used worldwide. In September 2019, the site's operator(s) said that it served approximately 400,000 requests per day.
    In addition to its intensive use, Sci-Hub stands out among other shadow libraries because of its easy use/reliability and because of the enormous size of its collection; a 2018 study estimated that Sci-Hub provided access to most of the scholarly publications with issued DOI numbers. On 15 July 2022, Sci-Hub reported that its collection comprised 88,343,822 files. Since December 2020, the site has paused uploads due to legal troubles. (Full article...)
  • Image 4 A plot of normal distribution (or bell-shaped curve) where each band has a width of 1 standard deviation – See also: 68–95–99.7 rule. In statistics, the standard deviation is a measure of the amount of variation of the values of a variable about its mean. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range. The standard deviation is commonly used in the determination of what constitutes an outlier and what does not. (Full article...)
    A plot of normal distribution (or bell-shaped curve) where each band has a width of 1 standard deviation – See also: 68–95–99.7 rule.

    In statistics, the standard deviation is a measure of the amount of variation of the values of a variable about its mean. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range. The standard deviation is commonly used in the determination of what constitutes an outlier and what does not. (Full article...)
  • Image 5 File:Ejaculation educational seq 4.png Example of an ejaculation Ejaculation is the discharge of semen (the ejaculate; normally containing sperm) from the testicles through the penis and out the urethra. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. After forming an erection, many men emit pre-ejaculatory fluid during stimulation prior to ejaculating. Ejaculation involves involuntary contractions of the pelvic floor and is normally linked with orgasm. It is a normal part of male human sexual development. (Full article...)

    Ejaculation is the discharge of semen (the ejaculate; normally containing sperm) from the testicles through the penis and out the urethra. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. After forming an erection, many men emit pre-ejaculatory fluid during stimulation prior to ejaculating. Ejaculation involves involuntary contractions of the pelvic floor and is normally linked with orgasm. It is a normal part of male human sexual development. (Full article...)
  • Image 6 Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into two or three major branches: the natural sciences (e.g., physics, chemistry, and biology), which study the physical world; and the behavioural sciences (e.g., economics, psychology, and sociology), which study individuals and societies. The formal sciences (e.g., logic, mathematics, and theoretical computer science), which study formal systems governed by axioms and rules, are sometimes described as being sciences as well; however, they are often regarded as a separate field because they rely on deductive reasoning instead of the scientific method or empirical evidence as their main methodology. Applied sciences are disciplines that use scientific knowledge for practical purposes, such as engineering and medicine. (Full article...)
    Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into two or three major branches: the natural sciences (e.g., physics, chemistry, and biology), which study the physical world; and the behavioural sciences (e.g., economics, psychology, and sociology), which study individuals and societies. The formal sciences (e.g., logic, mathematics, and theoretical computer science), which study formal systems governed by axioms and rules, are sometimes described as being sciences as well; however, they are often regarded as a separate field because they rely on deductive reasoning instead of the scientific method or empirical evidence as their main methodology. Applied sciences are disciplines that use scientific knowledge for practical purposes, such as engineering and medicine. (Full article...)
  • Image 7 Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes peer-reviewed online academic journals and books, conference papers, theses and dissertations, preprints, abstracts, technical reports, and other scholarly literature, including court opinions and patents. (Full article...)

    Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes peer-reviewed online academic journals and books, conference papers, theses and dissertations, preprints, abstracts, technical reports, and other scholarly literature, including court opinions and patents. (Full article...)
  • Image 8 The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and science. (Full article...)

    The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and science. (Full article...)
  • Image 9 The expansion of the universe according to the Big Bang theory in physics Physics is the scientific study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines. A scientist who specializes in the field of physics is called a physicist. (Full article...)
    The expansion of the universe according to the Big Bang theory in physics

    Physics is the scientific study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines. A scientist who specializes in the field of physics is called a physicist. (Full article...)
  • Image 10 In biology, taxonomy (from Ancient Greek τάξις (taxis) 'arrangement' and -νομία (-nomia) 'method') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. (Full article...)
    In biology, taxonomy (from Ancient Greek τάξις (taxis) 'arrangement' and -νομία (-nomia) 'method') is the scientific study of naming, defining (circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. (Full article...)
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