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Topic Review
Ejectors
Ejectors are broadly of two types based on geometric construction, constant area mixing (CAM) and constant pressure mixing (CPM). Eamesproposed a new design with constant rate of momentum change, which has the advantage of both CAM and CPM. Computational and experimental studies show better overall performance of ejectors with increases in critical condensing temperatures and higher entrainment ratios.
  • 7.7K
  • 19 Nov 2021
Topic Review
Features New to Windows 7
Some of the new features included in Windows 7 are advancements in touch, speech and handwriting recognition, support for virtual hard disks, support for additional file formats, improved performance on multi-core processors, improved boot performance, and kernel improvements. Some of the features which are present in versions up to and including Windows Vista were removed or changed.
  • 7.7K
  • 15 Nov 2022
Topic Review
Solid Waste Management in Middle East Arab Countries
Solid waste production, specifically construction waste, in Middle Eastern Arab countries has dramatically increased. This is characterized by several factors, including rapid urbanization, common food wasting habits, diverse culture, lack of proper planning of solid waste processes, insufficient equipment, as well as lack of proper funding. The exponential growth in solid waste generation rates has led to hazards to health and the environment, causing issues related to air and water pollution under the already increasing pressure of climate change.
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  • 17 Nov 2022
Topic Review
Synthetic Aperture Radar
SAR constellations 
  • 7.7K
  • 24 Aug 2020
Topic Review
Theravada
Theravāda (/ˌtɛrəˈvɑːdə/; Pāli, lit. "School of the Elders") is the most commonly accepted name of Buddhism's oldest existing school. The school's adherents, termed Theravādins, have preserved their version of Gautama Buddha's teaching in the Pāli Canon. The Pāli Canon is the only complete Buddhist canon surviving in a classical Indian language, Pāli, which serves as the school's sacred language and lingua franca. For over a millennium, theravādins have endeavored to preserve the dhamma as recorded in their school's texts.[web 1] In contrast to Mahāyāna and Vajrayāna, Theravāda tends to be conservative in matters of doctrine and monastic discipline. Modern Theravāda derives from the Mahāvihāra sect, a Sri Lankan branch of the Vibhajjavādins, a sub-sect of the Indian Sthavira Nikaya, which began to establish itself on the island from the 3rd century BCE onwards. It was in Sri Lanka that the Pāli Canon was written down and the school's commentary literature developed. From Sri Lanka, the Theravāda Mahāvihāra tradition subsequently spread to the rest of Southeast Asia. It is the dominant religion in Cambodia, Laos, Myanmar, Sri Lanka, and Thailand and is practiced by minorities in India, Bangladesh, China, Nepal, and Vietnam. The diaspora of all of these groups, as well as converts around the world, also practice Theravāda. During the modern era, new developments have included Buddhist modernism, the Vipassana movement which reinvigorated Theravāda meditation practice [web 1] and the Thai Forest Tradition which reemphasized forest monasticism.
  • 7.7K
  • 05 Dec 2022
Topic Review
Sound Vibration on Human Health
This entry presents a narrative review of research literature to “map the landscape” of the mechanisms of the effect of sound vibration on humans including the physiological, neurological, and biochemical. It begins by narrowing music to sound and sound to vibration. The focus is on low frequency sound (up to 250 Hz) including infrasound (1–16 Hz). Types of application are described and include whole body vibration, vibroacoustics, and focal applications of vibration. Literature on mechanisms of response to vibration is categorized into hemodynamic, neurological, and musculoskeletal. Basic mechanisms of hemodynamic effects including stimulation of endothelial cells and vibropercussion; of neurological effects including protein kinases activation, nerve stimulation with a specific look at vibratory analgesia, and oscillatory coherence; of musculoskeletal effects including muscle stretch reflex, bone cell progenitor fate, vibration effects on bone ossification and resorption, and anabolic effects on spine and intervertebral discs. In every category research on clinical applications are described. The conclusion points to the complexity of the field of vibrational medicine and calls for specific comparative research on type of vibration delivery, amount of body or surface being stimulated, effect of specific frequencies and intensities to specific mechanisms, and to greater interdisciplinary cooperation and focus. 
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  • 21 Jun 2021
Topic Review
2012 Phenomenon
The 2012 phenomenon was a range of eschatological beliefs that cataclysmic or transformative events would occur around 21 December 2012. This date was regarded as the end-date of a 5,126-year-long cycle in the Mesoamerican Long Count calendar, and festivities took place on 21 December 2012 to commemorate the event in the countries that were part of the Maya civilization (Mexico, Guatemala, Honduras, and El Salvador), with main events at Chichén Itzá in Mexico and Tikal in Guatemala. Various astronomical alignments and numerological formulae were proposed for this date. A New Age interpretation held that the date marked the start of a period during which Earth and its inhabitants would undergo a positive physical or spiritual transformation, and that 21 December 2012 would mark the beginning of a new era. Others suggested that the date marked the end of the world or a similar catastrophe. Scenarios suggested for the end of the world included the arrival of the next solar maximum, an interaction between Earth and the supermassive black hole at the center of the galaxy, or Earth's collision with a mythical planet called Nibiru. Scholars from various disciplines quickly dismissed predictions of cataclysmic events as they arose. Mayan scholars stated that no classic Mayan accounts forecast impending doom, and the idea that the Long Count calendar ends in 2012 misrepresented Mayan history and culture. Astronomers rejected the various proposed doomsday scenarios as pseudoscience which is easily refuted by elementary astronomical observations.
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  • 07 Nov 2022
Topic Review
Critical Factors in Renewable Energy Generation
The factors influencing the development of renewable energy in the electrical power sector can be grouped into four main clusters: (i) economic factors, (ii) legal and policy factors, (iii) social acceptance factors, and (iv) adverse impacts of renewable energy projects on the ecological environment.
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  • 16 Dec 2021
Topic Review
Grade Retention
Grade retention is a strategy for the remediation of learning or developmental delays. Students who cannot keep up with their peers or do not meet a predefined level repeat the same grade once again and by doing so have an extra year to get at the level that is needed to successfully manage the next grade. There are considerable doubts as regards the usefulness and effectiveness of retaining grades. Studies conclude that in the short term retaining grades may have a positive effect on academic achievement, but that this gain disappears in the longer term.
  • 7.7K
  • 30 Oct 2020
Topic Review
House of Bonaparte
The House of Bonaparte (originally Buonaparte) was an imperial and royal European dynasty founded in 1804 by Italian noble Carlo Buonaparte and his son Napoleon I, a French military leader of Italian heritage who had risen to notability out of the French Revolution and who in 1804 transformed the First French Republic into the First French Empire, five years after his coup d'état of November 1799. Napoleon turned the Grande Armée against every major European power and dominated continental Europe through a series of military victories during the Napoleonic Wars. He installed members of his family on the thrones of client states, extending the power of the dynasty. The House of Bonaparte formed the Imperial House of France during the French Empire, together with some non-Bonaparte family members. In addition to holding the title of Emperor of the French, the Bonaparte dynasty held various other titles and territories during the Napoleonic Wars, including their ancestral Kingdom of Italy, the Kingdom of Spain, the Kingdom of Westphalia, the Kingdom of Holland, and the Kingdom of Naples. The dynasty held power for around a decade until the Napoleonic Wars began to take their toll. Making very powerful enemies, such as Austria, Britain, Russia, and Prussia, as well as royalist (particularly Bourbon) restorational movements in France, Spain, the Two Sicilies, and Sardinia, the dynasty eventually collapsed due to the final defeat of Napoleon at the Battle of Waterloo and the restoration of former dynasties by the Congress of Vienna. During the reign of Napoleon I, the Imperial Family consisted of the Emperor's immediate relations – his wife, son, siblings, and some other close relatives, namely Joachim Murat, Joseph Fesch, and Eugène de Beauharnais. Between 1852 and 1870, there was a Second French Empire, when a member of the Bonaparte dynasty again ruled France: Napoleon III, the youngest son of Louis Bonaparte. However, during the Franco-Prussian War of 1870–1871, the dynasty was again ousted from the Imperial Throne. Since that time, there has been a series of pretenders. Supporters of the Bonaparte family's claim to the throne of France are known as Bonapartists. Current head Jean-Christophe, Prince Napoléon, has a Bourbon mother.
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  • 11 Nov 2022
Topic Review
Vegetable Oils as Lubricants
Vegetable oils have been used as metalworking fluids (MWFs) for many years, particularly in small-scale metalworking operations and in industries where environmental regulations are strict. Before the development of modern MWFs, vegetable oils were one of the most common lubricants used for metalworking tools. The use of vegetable oils can be traced back to ancient civilizations such as Egypt, Greece, and Rome, where olive oil was commonly used to lubricate metal tools and weapons. 
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  • 19 Apr 2023
Topic Review
Hoveyda–Grubbs Catalyst
Hoveyda–Grubbs-type complexes, ruthenium catalysts for olefin metathesis, have gained increased interest as a research target in the interdisciplinary research fields of chemistry and biology because of their high functional group selectivity in olefin metathesis reactions and stabilities in aqueous media.
  • 7.6K
  • 26 Mar 2021
Topic Review
Face with Tears of Joy Emoji
thumb|Appearance in the EmojiOne emoji set|167x167px Face with Tears of Joy (😂) is an emoji featuring a jovial face laughing, while also crying out tears. It can also be used for joking and teasing. It is the most commonly used emoji on social media websites such as Facebook, Snapchat, Twitter and Instagram. The emoji is also variously known as the lol emoji, joy emoji, laughing emoji or the laughing crying emoji.
  • 7.6K
  • 09 Nov 2022
Topic Review
35 Mm Film
35 mm film (millimeter) is the film gauge most commonly used for motion pictures and chemical still photography (see 135 film). The name of the gauge refers to the width of the photographic film, which consists of strips 34.98 ±0.03 mm (1.377 ±0.001 inches) wide. The standard negative pulldown for movies ("single-frame" format) is four perforations per frame along both edges, which results in 16 frames per foot of film. For still photography, the standard frame has eight perforations on each side. A variety of largely proprietary gauges were devised for the numerous camera and projection systems being developed independently in the late 19th century and early 20th century, ranging from 13 to 75 mm (0.51 to 2.95 in), as well as a variety of film feeding systems. This resulted in cameras, projectors, and other equipment having to be calibrated to each gauge. The 35 mm width, originally specified as ​1 3⁄8 inches, was introduced in 1892 by William Dickson and Thomas Edison, using 120 film stock supplied by George Eastman. Film 35 mm wide with four perforations per frame became accepted as the international standard gauge in 1909, and remained by far the dominant film gauge for image origination and projection until the advent of digital photography and cinematography, despite challenges from smaller and larger gauges, because its size allowed for a relatively good trade-off between the cost of the film stock and the quality of the images captured. The gauge has been versatile in application. It has been modified to include sound, redesigned to create a safer film base, formulated to capture color, has accommodated a bevy of widescreen formats, and has incorporated digital sound data into nearly all of its non-frame areas. Eastman Kodak, Fujifilm and Agfa-Gevaert are some companies that offered 35 mm films. Today Kodak is the last remaining manufacturer of motion picture film. The ubiquity of 35 mm movie projectors in commercial movie theaters made 35 mm the only motion picture format that could be played in almost any cinema in the world, until digital projection largely superseded it in the 21st century. It is difficult to compare the quality of film to digital media, but a good estimate would be about 33.6 megapixels (67.2 megapixels DSLR Bayer equivalent) would equal one 35-millimeter high quality color frame of film.
  • 7.6K
  • 18 Oct 2022
Topic Review
Dihedral (Aeronautics)
In aeronautics, dihedral is the angle between the left and right wings (or tail surfaces) of an aircraft. "Dihedral" is also used to describe the effect of sideslip on the rolling of the aircraft. Dihedral angle is the upward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. "Anhedral angle" is the name given to negative dihedral angle, that is, when there is a downward angle from horizontal of the wings or tailplane of a fixed-wing aircraft. Dihedral angle has a strong influence on dihedral effect, which is named after it. Dihedral effect is the amount of roll moment produced in proportion to the amount of sideslip. Dihedral effect is a critical factor in the stability of an aircraft about the roll axis (the spiral mode). It is also pertinent to the nature of an aircraft's Dutch roll oscillation and to maneuverability about the roll axis. Longitudinal dihedral is a comparatively obscure term related to the pitch axis of an airplane. It is the angle between the zero-lift axis of the wing and the zero-lift axis of the horizontal tail. Longitudinal dihedral can influence the nature of controllability about the pitch axis and the nature of an aircraft's phugoid-mode oscillation. When the term "dihedral" (of an aircraft) is used by itself it is usually intended to mean "dihedral angle". However, context may otherwise indicate that "dihedral effect" is the intended meaning.
  • 7.6K
  • 27 Oct 2022
Topic Review
Permian–Triassic Extinction Event
The Permian–Triassic extinction event, also known as the P–Tr extinction, the P–T extinction, the End-Permian Extinction, and colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, as well as between the Paleozoic and Mesozoic eras, approximately 252 million years ago. It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It was the largest known mass extinction of insects. Some 57% of all biological families and 83% of all genera became extinct. There is evidence for one to three distinct pulses, or phases, of extinction. Potential causes for those pulses include one or more large meteor impact events, massive volcanic eruptions (such as the Siberian Traps), and climate change brought on by large releases of underwater methane or methane-producing microbes. The speed of the recovery from the extinction is disputed. Some scientists estimate that it took 10 million years (until the Middle Triassic), due both to the severity of the extinction and because grim conditions returned periodically for another 5 million years. However, studies in Bear Lake County, near Paris, Idaho, showed a relatively quick rebound in a localized Early Triassic marine ecosystem, taking around 2 million years to recover, suggesting that the impact of the extinction may have been felt less severely in some areas than others.
  • 7.6K
  • 11 Oct 2022
Topic Review
2010 Flash Crash
The May 6, 2010, Flash Crash, also known as the Crash of 2:45, the 2010 Flash Crash or simply the Flash Crash, was a United States trillion-dollar stock market crash, which started at 2:32 p.m. EDT and lasted for approximately 36 minutes.:1 Stock indexes, such as the S&P 500, Dow Jones Industrial Average and Nasdaq Composite, collapsed and rebounded very rapidly. The Dow Jones Industrial Average had its second biggest intraday point drop (from the opening) up to that point, plunging 998.5 points (about 9%), most within minutes, only to recover a large part of the loss. It was also the second-largest intraday point swing (difference between intraday high and intraday low) up to that point, at 1,010.14 points. The prices of stocks, stock index futures, options and exchange-traded funds (ETFs) were volatile, thus trading volume spiked.:3 A CFTC 2014 report described it as one of the most turbulent periods in the history of financial markets.:1 When new regulations put in place following the 2010 Flash Crash proved to be inadequate to protect investors in the August 24, 2015 flash crash—"when the price of many ETFs appeared to come unhinged from their underlying value"—ETFs were put under greater scrutiny by regulators and investors. On April 21, 2015, nearly five years after the incident, the U.S. Department of Justice laid "22 criminal counts, including fraud and market manipulation" against Navinder Singh Sarao, a trader. Among the charges included was the use of spoofing algorithms; just prior to the Flash Crash, he placed thousands of E-mini S&P 500 stock index futures contracts which he planned on canceling later. These orders amounting to about "$200 million worth of bets that the market would fall" were "replaced or modified 19,000 times" before they were canceled. Spoofing, layering, and front running are now banned. The Commodity Futures Trading Commission (CFTC) investigation concluded that Sarao "was at least significantly responsible for the order imbalances" in the derivatives market which affected stock markets and exacerbated the flash crash. Sarao began his alleged market manipulation in 2009 with commercially available trading software whose code he modified "so he could rapidly place and cancel orders automatically." Traders Magazine journalist, John Bates, argued that blaming a 36-year-old small-time trader who worked from his parents' modest stucco house in suburban west London for sparking a trillion-dollar stock market crash is a little bit like blaming lightning for starting a fire" and that the investigation was lengthened because regulators used "bicycles to try and catch Ferraris." Furthermore, he concluded that by April 2015, traders can still manipulate and impact markets in spite of regulators and banks' new, improved monitoring of automated trade systems. As recently as May 2014, a CFTC report concluded that high-frequency traders "did not cause the Flash Crash, but contributed to it by demanding immediacy ahead of other market participants.":1 Some recent peer-reviewed research shows that flash crashes are not isolated occurrences, but have occurred quite often. Gao and Mizrach studied US equities over the period of 1993–2011. They show that breakdowns in market quality (such as flash crashes) have occurred in every year they examined and that, apart from the financial crisis, such problems have declined since the introduction of Reg NMS. They also show that 2010, while infamous for the Flash Crash, was not a year with an inordinate number of breakdowns in market quality.
  • 7.6K
  • 30 Nov 2022
Topic Review
Nose Ring (Animal)
A nose ring is inserted into the nose of an animal. Nose rings are used to control bulls and occasionally cows, and to help wean young cattle by preventing suckling. Nose rings are used on pigs to discourage rooting. Some nose rings are installed through a pierced hole in the nasal septum or rim of the nose and remain there, while others are temporary tools.
  • 7.6K
  • 03 Nov 2022
Topic Review
The Intelligent Reflecting Surface
The Intelligent Reflecting Surface (IRS) is a revolutionary technology to improve the performance of wireless data transmission systems. In particular, the wireless signal transmission environment is reconfigured by jointly adjusting a large number of small reflective units
  • 7.6K
  • 08 Apr 2022
Topic Review
Commune (Model of Government)
The commune, as a model of government, is generally advocated by some communists, revolutionary socialists, and anarchists. Communes are an organizational community with social cohesion derived from a shared culture. As a governing community, a commune often entails some degree of local governance, communal ownership, and cultural cohesion. However, models that do not include all three aspects may still be described as communes. At its core, a commune is just an organization which creates social conditions that prioritize the primacy of the collective over the individual. Many different forms of commune-based governments are possible, such as a local and sovereign community which is both a microstate and a nation-state, a federated commune which lacks a degree of sovereignty under the rule of a larger state, or a larger national community which focuses more on aspects of communal ownership rather than communal governance.
  • 7.6K
  • 09 Nov 2022
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