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Topic Review
Biomechanics of Table Tennis
Table tennis is a popular recreational and competitive sports at all levels. Recent research on table tennis maneuvers identified the differences between playing levels and between maneuvers using parameters which included ball and racket speed, joint kinematics and kinetics, electromyography, and plantar pressure distribution. Different maneuvers underlined changes on body posture and lines of movement which were accommodated particularly by the racket face angle, trunk rotation, knee and elbow joint movements, and thus different contributions of muscles. Higher-level players produced ball and strike at higher accuracy and repeatability but not necessarily lead to higher speed. In addition, higher-level players utilize superior whole-body coordination and footwork to compromise between agility and stability for a quality strike. Strengthening shoulder and wrist muscles could enhance the speed of the strike while personalized training shall be considered since motor coordination and adaptation vary among individuals.
  • 15.0K
  • 29 Oct 2020
Topic Review
List of Island Countries
This is a list of island countries. An island is a landmass (smaller than a continent) that is surrounded by water. Many island countries are spread over an archipelago, as is the case with the Federated States of Micronesia and Indonesia (both of which consist of thousands of islands). Others consist of a single island, such as Barbados or Nauru, or part of an island, such as the Dominican Republic or Brunei. Australia is a continent, although it has historically been referred to as an island, due to it having no land borders. The list also includes states with limited diplomatic recognition which have de facto control over territories entirely on the islands, such as Taiwan.[n 1] Indonesia is the world's largest island country by area (1,904,569 km2), and by total number of islands (more than 18,307), and is also the world's most populous island country, with a population of over 270 million (the fourth-largest population in the world, after China , India , and the United States ).
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  • 14 Oct 2022
Topic Review
G protein-coupled receptor in hepatocytes
G protein-coupled receptors (GPCRs) are cell surface receptors that mediate the function of extracellular ligands. Understanding how GPCRs work at the molecular level has important therapeutic implications, as 30-40% of the drugs currently in clinical use mediate therapeutic effects by acting on GPCRs. Like many other cell types, hepatocyte's function is regulated by GPCRs. A better understanding of the metabolic role of GPCRs in hepatocytes, the dominant constituent cells of the liver, could lead to the development of novel drugs that are clinically useful for the treatment of various metabolic diseases, including Type 2 diabetes, NAFLD, and NASH. 
  • 15.0K
  • 06 Nov 2020
Topic Review
2015–16 Stock Market Selloff
The 2015–16 stock market selloff, also known as The Great Fall of China, was the period of decline in the value of stock prices globally that occurred between June 2015 to June 2016. It included the 2015–16 Chinese stock market turbulence, in which the SSE Composite Index fell 43% in just over 2 months between June 2015 and August 2015, which culminated in the devaluation of the yuan. Investors sold shares globally as a result of slowing growth in the GDP of China, a fall in petroleum prices, the Greek debt default in June 2015, the effects of the end of quantitative easing in the United States in October 2014, a sharp rise in bond yields in early 2016, and finally, in June 2016, the 2016 United Kingdom European Union membership referendum, in which Brexit was voted upon. By July 2016, the Dow Jones Industrial Average (DJIA) recovered and achieved record highs. The FTSE 100 Index did not do so until later in 2016.
  • 15.0K
  • 29 Nov 2022
Topic Review
Carboniferous Rainforest Collapse
The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. It altered the vast coal forests that covered the equatorial region of Euramerica (Europe and America). This event may have fragmented the forests into isolated 'islands', which in turn caused dwarfism and, shortly after, extinction of many plant and animal species. Following the event, coal-forming tropical forests continued in large areas of the Earth, but their extent and composition were changed. The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of the Pennsylvanian (Upper Carboniferous).
  • 15.0K
  • 08 Oct 2022
Topic Review
Fairy Tale
A fairy tale, fairytale, wonder tale, magic tale, or Märchen is an instance of a folklore genre that takes the form of a short story. Such stories typically feature entities such as dwarfs, dragons, elves, fairies, giants, gnomes, goblins, griffins, mermaids, talking animals, trolls, unicorns, or witches, and usually magic or enchantments. In most cultures, there is no clear line separating myth from folk or fairy tale; all these together form the literature of preliterate societies. Fairy tales may be distinguished from other folk narratives such as legends (which generally involve belief in the veracity of the events described) and explicit moral tales, including beast fables. In less technical contexts, the term is also used to describe something blessed with unusual happiness, as in "fairy-tale ending" (a happy ending) or "fairy-tale romance". Colloquially, the term "fairy tale" or "fairy story" can also mean any far-fetched story or tall tale; it is used especially of any story that not only is not true, but could not possibly be true. Legends are perceived as real; fairy tales may merge into legends, where the narrative is perceived both by teller and hearers as being grounded in historical truth. However, unlike legends and epics, fairy tales usually do not contain more than superficial references to religion and to actual places, people, and events; they take place "once upon a time" rather than in actual times. Fairy tales occur both in oral and in literary form; the name "fairy tale" ("conte de fées" in French) was first ascribed to them by Madame d'Aulnoy in the late 17th century. Many of today's fairy tales have evolved from centuries-old stories that have appeared, with variations, in multiple cultures around the world. The history of the fairy tale is particularly difficult to trace because only the literary forms can survive. Still, according to researchers at universities in Durham and Lisbon, such stories may date back thousands of years, some to the Bronze Age more than 6,500 years ago. Fairy tales, and works derived from fairy tales, are still written today. Folklorists have classified fairy tales in various ways. The Aarne-Thompson classification system and the morphological analysis of Vladimir Propp are among the most notable. Other folklorists have interpreted the tales' significance, but no school has been definitively established for the meaning of the tales.
  • 15.0K
  • 17 Nov 2022
Topic Review
GNU C Library
The GNU C Library, commonly known as glibc, is the GNU Project's implementation of the C standard library. Despite its name, it now also directly supports C++ (and, indirectly, other programming languages). It was started in the 1980s by the Free Software Foundation (FSF) for the GNU operating system. Released under the GNU Lesser General Public License, glibc is free software. The GNU C Library project provides the core libraries for the GNU system, as well as many systems that use Linux as the kernel. These libraries provide critical APIs including ISO C11, POSIX.1-2008, BSD, OS-specific APIs and more. These APIs include such foundational facilities as open, read, write, malloc, printf, getaddrinfo, dlopen, pthread create, crypt, login, exit and more.
  • 14.9K
  • 21 Nov 2022
Topic Review
Social Presence Theory
Social presence theory explores how the "sense of being with another" is influenced by digital interfaces in human-computer interactions. Developed from the foundations of interpersonal communication and symbolic interactionism, social presence theory was first formally introduced by John Short, Ederyn Williams, and Bruce Christie in The Social Psychology of Telecommunications. Research on social presence theory has recently developed to examine the efficacy of telecommunications media, including SNS communications. The theory notes that computer-based communication is lower in social presence than face-to-face communication, but different computer-based communications can affect the levels of social presence between communicators and receivers.
  • 14.8K
  • 02 Dec 2022
Topic Review
Telegram (Service)
Telegram is a cloud-based instant messaging and voice over IP service developed by Telegram Messenger LLP, a privately held company registered in London, United Kingdom , founded by the Russian entrepreneur Pavel Durov. Telegram client apps are available for Android, iOS, Windows Phone, Windows NT, macOS and Linux. Users can send messages and exchange photos, videos, stickers, audio and files of any type. Telegram's client-side code is open-source software but the source code for recent versions is not always immediately published, whereas its server-side code is closed-source and proprietary. The service also provides APIs to independent developers. In March 2018, Telegram stated that it had 200 million monthly active users. According to its CEO, (As of April 2017), Telegram’s annual growth rate was greater than 50%. Messages and media in Telegram are only client-server encrypted and stored on the servers by default. The service provides end-to-end encryption for voice calls, and optional end-to-end encrypted "secret" chats between two online users, yet not for groups or channels. Telegram's security model has received notable criticism by cryptography experts. They criticized the general security model of permanently storing all contacts, messages and media together with their decryption keys on its servers by default and by not enabling end-to-end encryption for messages by default. Pavel Durov has argued that this is because it helps to avoid third-party unsecure backups, and to allow users to access messages and files from any device. Cryptography experts have furthermore criticized Telegram's use of a custom-designed encryption protocol that has not been proven reliable and secure. Telegram has faced censorship or outright bans in some countries over accusations that the app's services have been used to facilitate illegal activities, such as protests and terrorism, as well as declining demands to facilitate government access to user data and communications.
  • 14.7K
  • 21 Nov 2022
Topic Review
Drag Polar
The drag polar or drag curve is the relationship between the lift on an aircraft and its drag, expressed in terms of the dependence of the drag coefficient on the lift coefficient. It may be described by an equation or displayed in a diagram called a polar plot.
  • 14.7K
  • 24 Oct 2022
Topic Review
Chief Justice of Pakistan
The chief justice of Pakistan (Urdu: منصف اعظم پاکستان) (initials as CJP) is the head of the court system of Pakistan (the judicature branch of government) and the chief judge of the Supreme Court of Pakistan. The officeholder is the senior most of 17 senior justices of the Supreme Court of Pakistan. The Federal Court of Pakistan was established by Governor-General Jinnah's Order in February 1948. Until 1956, the chief justice and senior justices were known by the title of 'Federal Judge', and the Federal Court of Pakistan operated out of a wing of the Lahore High Court, despite the federal capital's location in Karachi. The enactment of Pakistan's first constitution in March 1956 redesigned it as the 'Supreme Court of Pakistan.' The chief justice is the chief administrative officer of the country's court system and the highest judicial officer, ranking immediately above the chief justice of the Federal Shariat Court, and is responsible for supervising federal judicial policies, and conducting judicial business in the Supreme Court. Nomination for the appointment of the chief justice is made by the prime minister of Pakistan, and final appointments are confirmed by the president of Pakistan. Presiding over the oral arguments before the court, the chief justice has significant agenda-setting power over meetings of the Supreme Court. In modern tradition[clarification needed], the chief justice has the ceremonial duty of administering the oath of office of the president of Pakistan. The first chief justice was Sir Abdul Rashid. The current chief justice is Umar Ata Bandial; incumbent since 2 February 2022.
  • 14.7K
  • 21 Nov 2022
Topic Review
Vocaloid
Vocaloid is a singing voice synthesizer and the first engine released in the Vocaloid series. It was succeeded by Vocaloid 2. This version was made to be able to sing both English and Japanese.
  • 14.7K
  • 17 Oct 2022
Topic Review
Religious Cosmology
Religious cosmology is an explanation of the origin, evolution, and eventual fate of the universe, from a religious perspective. This may include beliefs on origin in the form of a creation myth, subsequent evolution, current organizational form and nature, and eventual fate or destiny. There are various traditions in religion or religious mythology asserting how and why everything is the way it is and the significance of it all. Religious cosmologies describe the spatial lay-out of the universe in terms of the world in which people typically dwell as well as other dimensions, such as the seven dimensions of religion; these are ritual, experiential and emotional, narrative and mythical, doctrinal, ethical, social, and material. Religious mythologies may include descriptions of an act or process of creation by a creator deity or a larger pantheon of deities, explanations of the transformation of chaos into order, or the assertion that existence is a matter of endless cyclical transformations. Religious cosmology differs from a strictly scientific cosmology informed by the results of the study of astronomy and similar fields, and may differ in conceptualizations of the world's physical structure and place in the universe, its creation, and forecasts or predictions on its future. The scope of religious cosmology is more inclusive than a strictly scientific cosmology (physical cosmology) in that religious cosmology is not limited to experiential observation, testing of hypotheses, and proposals of theories; for example, religious cosmology may explain why everything is the way it is or seems to be the way it is and prescribing what humans should do in context. Variations in religious cosmology include those such as from India Buddhism, Hindu, and Jain; the religious beliefs of China, Chinese Buddhism, Taoism and Confucianism, Japan's Shintoisim and the beliefs of the Abrahamic faiths, such as Judaism, Christianity, and Islam. Religious cosmologies have often developed into the formal logics of metaphysical systems, such as Platonism, Neoplatonism, Gnosticism, Taoism, Kabbalah, Wuxing or the great chain of being.
  • 14.7K
  • 20 Oct 2022
Topic Review
Protection Motivation Theory
Protection motivation theory (PMT) was originally created to help understand individual human responses to fear appeals. Protection motivation theory proposes that people protect themselves based on two factors: threat appraisal and coping appraisal. Threat appraisal assesses the severity of the situation and examines how serious the situation is, while coping appraisal is how one responds to the situation. Threat appraisal consists of the perceived severity of a threatening event and the perceived probability of the occurrence, or vulnerability. Coping appraisal consists of perceived response efficacy, or an individual's expectation that carrying out the recommended action will remove the threat, and perceived self efficacy, or the belief in one's ability to execute the recommended courses of action successfully. PMT is one model that explains why people engage in unhealthy practices and offers suggestions for changing those behaviors. It is educational and motivational. Primary prevention: taking measures to combat the risk of developing a health problem. (e.g., controlling weight to prevent high blood pressure). Secondary prevention: taking steps to prevent a condition from becoming worse. (e.g., remembering to take daily medication to control blood pressure). Another psychological model that describes self-preservation and processing of fear is terror management theory.
  • 14.7K
  • 09 Oct 2022
Topic Review
Marriageable Age
Marriageable age (or marriage age) is the minimum age at which a person is allowed by law to marry, either as a right or subject to parental, judicial or other forms of approval. Age and other prerequisites to marriage vary between jurisdictions, but in the vast majority of jurisdictions, the marriage age as a right is set at the age of majority. Nevertheless, most jurisdictions allow marriage at a younger age with parental or judicial approval, and some also allow younger people to marry if the female is pregnant. Until recently, the marriageable age for girls was lower in many jurisdictions than for boys, on the premise that girls mature at an earlier age than boys. This law has been viewed to be discriminatory, so that in many countries the marriageable age of girls has been raised to equal that of boys. That age is most commonly 18, but there are variations, some higher and some lower. The marriageable age should not be confused with the age of maturity or the age of consent, though, they may be the same in many places. In many developing countries, the official age prescriptions stand as mere guidelines. International organizations, such as UNICEF, regard a marriage by a person below the age of 18 as a child marriage and a violation of human rights. The 55 parties to the 1962 Convention on Consent to Marriage, Minimum Age for Marriage, and Registration of Marriages have agreed to specify a minimum marriage age by statute law‚ to override customary, religious, and tribal laws and traditions. When the marriageable age under a law of a religious community is lower than that under the law of the land, the state law prevails. However, some religious communities do not accept the supremacy of state law in this respect, which may lead to child marriage or forced marriage. The 123 parties to the 1956 Supplementary Convention on the Abolition of Slavery have agreed to adopt a prescribed “suitable” minimum age for marriage.
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  • 21 Nov 2022
Topic Review
Bible Belt
The Bible Belt is a region of the Southern United States in which socially conservative Protestant Christianity plays a strong role in society and politics, and church attendance across the denominations is generally higher than the nation's average. The region contrasts with the religiously diverse Midwest and Great Lakes, and the Mormon corridor in Utah and southern Idaho. Whereas the states with the highest percentage of residents identifying as non-religious are in the West and New England regions of the United States (with Vermont at 37%, ranking the highest), in the Bible Belt state of Alabama it is just 12%, and Tennessee has the highest proportion of evangelical Protestants, at 52%. The evangelical influence is strongest in northern Georgia, Tennessee , Alabama, Mississippi, North Carolina, southern and western Virginia, West Virginia, the Upstate region of South Carolina, and East Texas . The earliest known usage of the term "Bible Belt" was by American journalist and social commentator H. L. Mencken, who in 1924 wrote in the Chicago Daily Tribune: "The old game, I suspect, is beginning to play out in the Bible Belt." In 1927, Mencken claimed the term as his invention. The term is now also used in other countries for regions with higher religious doctrine adoption.
  • 14.6K
  • 24 Nov 2022
Topic Review
History of Wind Power
Wind power has been used as long as humans have put sails into the wind. For more than two millennia wind-powered machines have ground grain and pumped water. Wind power was widely available and not confined to the banks of fast-flowing streams, or later, requiring sources of fuel. Wind-powered pumps drained the polders of the Netherlands, and in arid regions such as the American mid-west or the Australian outback, wind pumps provided water for livestock and steam engines. With the development of electric power, wind power found new applications in lighting buildings remote from centrally-generated power. Throughout the 20th century parallel paths developed small wind plants suitable for farms or residences, and larger utility-scale wind generators that could be connected to electricity grids for remote use of power. Today wind-powered generators operate in every size range between tiny plants for battery charging at isolated residences, up to near-gigawatt sized offshore wind farms that provide electricity to national electrical networks. By 2014, over 240,000 commercial-sized wind turbines were operating in the world, producing 4% of the world's electricity.
  • 14.6K
  • 02 Oct 2022
Topic Review
Armenia
Armenia, officially the Republic of Armenia, is a landlocked country in the Armenian Highlands of Eastern Europe. Due to its location in the South Caucasus, Armenia is sometimes described as transcontinental, spanning both Eastern Europe and Western Asia. It is bordered by Turkey to the west, Georgia to the north, the Lachin corridor (under a Russian peacekeeping force) and Azerbaijan to the east, and Iran and the Azerbaijani exclave of Nakhchivan to the south. Yerevan is the capital and largest city. Armenia is a unitary, multi-party, democratic nation-state with an ancient cultural heritage. The first Armenian state of Urartu was established in 860 BC, and by the 6th century BC it was replaced by the Satrapy of Armenia. The Kingdom of Armenia reached its height under Tigranes the Great in the 1st century BC and in the year 301 became the first state in the world to adopt Christianity as its official religion, The ancient Armenian kingdom was split between the Byzantine and Sasanian Empires around the early 5th century. Under the Bagratuni dynasty, the Bagratid Kingdom of Armenia was restored in the 9th century. Declining due to the wars against the Byzantines, the kingdom fell in 1045 and Armenia was soon after invaded by the Seljuk Turks. An Armenian principality and later a kingdom Cilician Armenia was located on the coast of the Mediterranean Sea between the 11th and 14th centuries. Between the 16th and 19th centuries, the traditional Armenian homeland composed of Eastern Armenia and Western Armenia came under the rule of the Ottoman and Persian empires, repeatedly ruled by either of the two over the centuries. By the 19th century, Eastern Armenia had been conquered by the Russian Empire, while most of the western parts of the traditional Armenian homeland remained under Ottoman rule. During World War I, 1.5 million Armenians living in their ancestral lands in the Ottoman Empire were systematically exterminated in the Armenian genocide. In 1918, following the Russian Revolution, all non-Russian countries declared their independence after the Russian Empire ceased to exist, leading to the establishment of the First Republic of Armenia. By 1920, the state was incorporated into the Transcaucasian Socialist Federative Soviet Republic, and in 1922 became a founding member of the Soviet Union. In 1936, the Transcaucasian state was dissolved, transforming its constituent states, including the Armenian Soviet Socialist Republic, into full Union republics. The modern Republic of Armenia became independent in 1991 during the dissolution of the Soviet Union. Armenia is a developing country and ranks 81st on the Human Development Index (2018). Its economy is primarily based on industrial output and mineral extraction. While Armenia is geographically located in the South Caucasus, it is generally considered geopolitically European. Since Armenia aligns itself in many respects geopolitically with Europe, the country is a member of numerous European organizations including the Council of Europe, the Eastern Partnership, Eurocontrol, the Assembly of European Regions, and the European Bank for Reconstruction and Development. Armenia is also a member of certain regional groups throughout Eurasia, including the Asian Development Bank, the Collective Security Treaty Organization, the Eurasian Union, and the Eurasian Development Bank. Armenia supports the de facto independent Artsakh, which was proclaimed in 1991. Armenia also recognises the Armenian Apostolic Church, the world's oldest national church, as the country's primary religious establishment. The unique Armenian alphabet was created by Mesrop Mashtots in 405 AD.
  • 14.6K
  • 10 May 2023
Topic Review
Environmental Risk Factors
Environmental health is a growing area of knowledge, continually increasing and updating the body of evidence linking the environment to human health.
  • 14.6K
  • 03 Dec 2022
Topic Review
Fedora Version History
Fedora is a popular Linux distribution developed by the community-supported Fedora Project and is sponsored by Red Hat. Fedora attempts to maintain a six-month release schedule, offering new versions in May and November, although some releases have experienced minor delays.
  • 14.6K
  • 28 Oct 2022
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