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Topic Review
Tudor Rose
The Tudor rose (sometimes called the Union rose) is the traditional floral heraldic emblem of England and takes its name and origins from the House of Tudor, which united the House of Lancaster and the House of York. The Tudor rose consists of five white inner petals, representing the House of York, and five red outer petals to represent the House of Lancaster.
  • 2.9K
  • 16 Nov 2022
Topic Review
Cyclic Quadrilateral
In Euclidean geometry, a cyclic quadrilateral or inscribed quadrilateral is a quadrilateral whose vertices all lie on a single circle. This circle is called the circumcircle or circumscribed circle, and the vertices are said to be concyclic. The center of the circle and its radius are called the circumcenter and the circumradius respectively. Other names for these quadrilaterals are concyclic quadrilateral and chordal quadrilateral, the latter since the sides of the quadrilateral are chords of the circumcircle. Usually the quadrilateral is assumed to be convex, but there are also crossed cyclic quadrilaterals. The formulas and properties given below are valid in the convex case. The word cyclic is from the Ancient Greek κύκλος (kuklos) which means "circle" or "wheel". All triangles have a circumcircle, but not all quadrilaterals do. An example of a quadrilateral that cannot be cyclic is a non-square rhombus. The section characterizations below states what necessary and sufficient conditions a quadrilateral must satisfy to have a circumcircle.
  • 2.9K
  • 27 Oct 2022
Topic Review
Sina Weibo
Sina Weibo (NASDAQ: WB) (新浪微博) is a Chinese microblogging (weibo) website. Launched by Sina Corporation on 14 August 2009, it is one of the biggest social media platforms in China, with over 445 million monthly active users as of Q3 2018. The platform has been a huge financial success, with surging stocks, lucrative advertising sales and high revenue and total earnings per quarter. At the start of 2018, it surpassed the US$30 billion market valuation mark for the first time. In March 2014, Sina Corporation announced a spinoff of Weibo as a separate entity and filed an IPO under the symbol WB. Sina carved out 11% of Weibo in the IPO, with Alibaba owning 32% post-IPO. The company began trading publicly on 17 April 2014. In March 2017, Sina launched Sina Weibo International Version. This new version has a clean, concise user interface design, as well as an ad-free feature; while its volume is very small, only occupying one-fifth of the space of the original, it still performs all of the original's functions. In June 2018, Sina Weibo reached 413 million active users. In November 2018, Sina Weibo suspended its registration function for minors under the age of 14. In July 2019, Sina Weibo announced that it would launch a two-month campaign to clean up pornographic and vulgar information, named The Blue Plan. Sina Weibo has attracted criticism over censoring its users.
  • 2.9K
  • 02 Nov 2022
Topic Review
Epiphany (Feeling)
An epiphany (from the ancient Greek ἐπιφάνεια, epiphanea, "manifestation, striking appearance") is an experience of a sudden and striking realization. Generally the term is used to describe scientific breakthrough, religious or philosophical discoveries, but it can apply in any situation in which an enlightening realization allows a problem or situation to be understood from a new and deeper perspective. Epiphanies are studied by psychologists and other scholars, particularly those attempting to study the process of innovation. Epiphanies are relatively rare occurrences and generally follow a process of significant thought about a problem. Often they are triggered by a new and key piece of information, but importantly, a depth of prior knowledge is required to allow the leap of understanding. Famous epiphanies include Archimedes's discovery of a method to determine the volume of an irregular object ("Eureka!") and Isaac Newton's realization that a falling apple and the orbiting moon are both pulled by the same force.
  • 2.9K
  • 30 Nov 2022
Topic Review
Single-Speed Bicycle
A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle. There are many types of modern single speed bicycles; BMX bicycles, most bicycles designed for children, cruiser type bicycles, classic commuter bicycles, unicycles, bicycles designed for track racing, fixed-gear road bicycles, and single-speed mountain and cyclocross bikes. Although most fixed-gear bicycles (fixies) are technically single speed, the term single-speed generally refers to a single gear ratio bicycle with a freewheel mechanism to allow it to coast.
  • 2.8K
  • 20 Oct 2022
Topic Review
Domain Fronting
Domain fronting is a technique for Internet censorship circumvention that uses different domain names in different communication layers of an HTTPS connection to discreetly connect to a different target domain than is discernable to third parties monitoring the requests and connections. Due to quirks in security certificates, the redirect systems of the content delivery networks (CDNs) used as 'domain fronts', and the protection provided by HTTPS, censors are typically unable to differentiate circumvention ("domain-fronted") traffic from overt non-fronted traffic for any given domain name. As such they are forced to either allow all traffic to the domain front—including circumvention traffic—or block the domain front entirely, which may result in expensive collateral damage and has been likened to "blocking the rest of the Internet".[note 1] Domain fronting does not conform to HTTP standards that require the SNI extension and HTTP Host header to contain the same domain. Large cloud service providers, including Amazon and Google, now actively prohibit domain fronting, which has made it "largely non-viable"[note 1] as a censorship bypass technique.
  • 2.8K
  • 06 Oct 2022
Topic Review
Guccifer 2.0
"Guccifer 2.0" is a persona which claimed to be the hacker(s) that hacked into the Democratic National Committee (DNC) computer network and then leaked its documents to the media, the website WikiLeaks, and a conference event. Some of the documents "Guccifer 2.0" released to the media appear to be forgeries cobbled together from public information and previous hacks, which had been mixed with disinformation. According to indictments in February 2018, the persona is operated by Russian military intelligence agency GRU. On July 13, 2018, Special Counsel Robert Mueller indicted 12 GRU agents for allegedly perpetrating the cyberattacks. The U.S. Intelligence Community concluded that some of the genuine leaks from "Guccifer 2.0" were part of a series of cyberattacks on the DNC committed by two Russian military intelligence groups, and that "Guccifer 2.0" is actually a persona created by Russian intelligence services to cover for their interference in the 2016 U.S. presidential election. This conclusion is based on analyses conducted by various private sector cybersecurity individuals and firms, including CrowdStrike, Fidelis Cybersecurity, FireEye's Mandiant, SecureWorks, ThreatConnect, Trend Micro, and the security editor for Ars Technica. The Russian government denies involvement in the theft, and "Guccifer 2.0" denied links to Russia. WikiLeaks founder Julian Assange said multiple parties had access to DNC emails and that there was "no proof" Russia was behind the attack. In March 2018, Special Counsel Robert Mueller took over investigation of Guccifer 2.0 from the FBI while it was reported that forensic determination had found the Guccifer 2.0 persona to be a "particular military intelligence directorate (GRU) officer working out of the agency's headquarters on Grizodubovoy Street in Moscow".
  • 2.8K
  • 10 Oct 2022
Topic Review
Social Hacking
Social hacking describes the act of attempting to manipulate outcomes of social behaviour through orchestrated actions. The general function of social hacking is to gain access to restricted information or to a physical space without proper permission. Most often, social hacking attacks are achieved by impersonating an individual or group who is directly or indirectly known to the victims or by representing an individual or group in a position of authority. This is done through pre-meditated research and planning to gain victims’ confidence. Social hackers take great measures to present overtones of familiarity and trustworthiness to elicit confidential or personal information. Social hacking is most commonly associated as a component of “social engineering”. Although the practice involves exercising control over human behaviour rather than computers, the term "social hacking" is also used in reference to online behaviour and increasingly, social media activity. The technique can be used in multiple ways that affect public perception and conversely, increase public awareness of social hacking activity. However, while awareness helps reduce the volume of hacks being carried out, technology has allowed for attack tools to become more sophisticated.
  • 2.8K
  • 20 Oct 2022
Topic Review
Bibliography of Encyclopedias
This is intended to be as comprehensive as possible list of encyclopedias and encyclopedic/biographical dictionaries ever published in any language. The list will not include reprinted editions but it is intended to list an alphabetical bibliography by theme and language to anything which resembles an A-Z encyclopedia or encyclopedic dictionary, both print and online. Entries are in the English language unless specifically stated as otherwise. Several entries may overlap and be listed under several different topics. For a simple list without bibliographic information see Lists of encyclopedias.
  • 2.7K
  • 14 Oct 2022
Topic Review
Trigonometry
Trigonometry (from grc τρίγωνον (trígōnon) 'triangle', and μέτρον (métron) 'measure') is a branch of mathematics that studies relationships between side lengths and angles of triangles. The field emerged in the Hellenistic world during the 3rd century BC from applications of geometry to astronomical studies. The Greeks focused on the calculation of chords, while mathematicians in India created the earliest-known tables of values for trigonometric ratios (also called trigonometric functions) such as sine. Throughout history, trigonometry has been applied in areas such as geodesy, surveying, celestial mechanics, and navigation. Trigonometry is known for its many identities. These trigonometric identities are commonly used for rewriting trigonometrical expressions with the aim to simplify an expression, to find a more useful form of an expression, or to solve an equation.
  • 2.7K
  • 31 Oct 2022
Topic Review
Broken/Angular Diameter
The angular diameter, angular size, apparent diameter, or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture (of a lens). The angular diameter can alternatively be thought of as the angle through which an eye or camera must rotate to look from one side of an apparent circle to the opposite side. Angular radius equals half of the angular diameter.
  • 2.7K
  • 04 Nov 2022
Topic Review
Applications of VR
Applications of VR (also known as virtual reality) can be found in fields as diverse as entertainment, marketing, education, medicine, and many others. They provide numerous possibilities for users to explore virtual realities for various purposes.
  • 2.7K
  • 01 Dec 2022
Topic Review
Dragon King Theory
Dragon king (DK) is a double metaphor for an event that is both extremely large in size or impact (a "king") and born of unique origins (a "dragon") relative to its peers (other events from the same system). DK events are generated by / correspond to mechanisms such as positive feedback, tipping points, bifurcations, and phase transitions, that tend to occur in nonlinear and complex systems, and serve to amplify DK events to extreme levels. By understanding and monitoring these dynamics, some predictability of such events may be obtained. The theory has been developed by Didier Sornette, who hypothesizes that many of the crises that we face are in fact DK rather than black swans—i.e., they may be predictable to some degree. Given the importance of crises to the long-term organization of a variety of systems, the DK theory urges that special attention be given to the study and monitoring of extremes, and that a dynamic view be taken. From a scientific viewpoint, such extremes are interesting because they may reveal underlying, often hidden, organizing principles. Practically speaking, one should study extreme risks, but not forget that significant uncertainty will almost always be present, and should be rigorously considered in decisions regarding risk management and design. The theory of DK is related to concepts such as black swan theory, outliers, complex systems, nonlinear dynamics, power laws, extreme value theory, prediction, extreme risks, and risk management.
  • 2.7K
  • 23 Oct 2022
Topic Review
Location-Based Service
A location-based service (LBS) is a general term denoting software services which utilize geographic data and information to provide services or information to users. LBS can be used in a variety of contexts, such as health, indoor object search, entertainment, work, personal life, etc. Commonly used examples of location based services include navigation software, social networking services, location-based advertising, and tracking systems. LBS can also include mobile commerce when taking the form of coupons or advertising directed at customers based on their current location. They include personalized weather services and even location-based games. LBS is critical to many businesses as well as government organizations to drive real insight from data tied to a specific location where activities take place. The spatial patterns that location-related data and services can provide is one of its most powerful and useful aspects where location is a common denominator in all of these activities and can be leveraged to better understand patterns and relationships. Banking, surveillance, online commerce, and many weapon systems are dependent on LBS. Access policies are controlled by location data and/or time-of-day constraints, or a combination thereof. As such, an LBS is an information service and has a number of uses in social networking today as information, in entertainment or security, which is accessible with mobile devices through the mobile network and which uses information on the geographical position of the mobile device. This concept of location based systems is not compliant with the standardized concept of real-time locating systems (RTLS) and related local services, as noted in ISO/IEC 19762-5 and ISO/IEC 24730-1. While networked computing devices generally do very well to inform consumers of days old data, the computing devices themselves can also be tracked, even in real-time. LBS privacy issues arise in that context, and are documented below.
  • 2.6K
  • 25 Oct 2022
Topic Review
List of Dell PowerEdge Servers
Dell PowerEdge is a server line by Dell, following the naming convention for other Dell products: the PowerVault (data storage) and the PowerConnect (data transfer & switches). Below is an overview of current and former servers within Dell's PowerEdge product line. Different models are or were available as towers, 19-inch racks or blades. In the current naming scheme, towers are designated by T, racks by R, and blades by M (for modular). The 19″ rack-servers come in different physical heights expressed in rack units or U. Most modern servers are either 1U or 2U high while in the past the 4U was more common.
  • 2.6K
  • 21 Oct 2022
Topic Review
Relative Direction
The most common relative directions are left, right, forward(s), backward(s), up, and down. No absolute direction corresponds to any of the relative directions. This is a consequence of the translational invariance of the laws of physics: nature, loosely speaking, behaves the same no matter what direction one moves. As demonstrated by the Michelson-Morley null result, there is no absolute inertial frame of reference. There are definite relationships between the relative directions, however. Left and right, forward and backward, and up and down are three pairs of complementary directions, each pair orthogonal to both of the others. Relative directions are also known as egocentric coordinates.
  • 2.6K
  • 24 Nov 2022
Topic Review
Power Architecture
Power Architecture is a registered trademark for similar reduced instruction set computing (RISC) instruction sets for microprocessors developed and manufactured by such companies as IBM, Freescale/NXP, AppliedMicro, LSI, Teledyne e2v and Synopsys. The governing body is Power.org, comprising over 40 companies and organizations. "Power Architecture" is a broad term including all products based on newer POWER, PowerPC and Cell processors. The term "Power Architecture" should not be confused with IBM's different generations of "POWER Instruction Set Architecture", an earlier instruction set for IBM RISC processors of the 1990s from which the PowerPC instruction set was derived. Power Architecture is a family name describing processor architecture, software, toolchain, community and end-user appliances and not a strict term describing specific products or technologies. More details and documentation on the Power Architecture can be found on the IBM Portal for OpenPOWER.
  • 2.6K
  • 18 Nov 2022
Topic Review
Social Trap
In psychology, a social trap is a conflict of interest or perverse incentive where individuals or a group of people act to obtain short-term individual gains, which in the long run leads to a loss for the group as a whole. Social traps are the cause of countless environmental issues, including overfishing, energy "brownout" and "blackout" power outages during periods of extreme temperatures, the overgrazing of cattle on the Sahelian Desert, the destruction of the rainforest by logging interests and agriculture, and, most importantly, climate change.
  • 2.5K
  • 01 Dec 2022
Topic Review
Tether (Cryptocurrency)
Tether (often referred to by one of its currency codes, USD₮), is an asset-backed cryptocurrency stablecoin. It was launched by the company Tether Limited Inc. in 2014. Tether Limited is owned by the Hong Kong-based company iFinex Inc., which also owns the Bitfinex cryptocurrency exchange. As of July 2022, Tether Limited has minted the USDT stablecoin on ten protocols and blockchains. Tether is described as a stablecoin because it was originally designed to be valued at USD $1.00, with Tether Limited maintaining USD $1.00 of asset reserves for each USDT issued.
  • 2.5K
  • 16 Nov 2022
Topic Review
Fallout Shelter (Video Game)
Fallout Shelter is a free-to-play simulation video game developed by Bethesda Game Studios, with assistance by Behaviour Interactive, and published by Bethesda Softworks. Part of the Fallout series, it was released worldwide for iOS devices in June 2015, for Android devices in August 2015, for Microsoft Windows in July 2016, Xbox One in February 2017, and PlayStation 4 and Nintendo Switch in June 2018. The game is also available on Tesla vehicles. The game tasks the player with building and effectively managing their own Vault, a fallout shelter. Upon release, Fallout Shelter received mostly positive reviews. Critics enjoyed the game's extension of the Fallout universe, the core gameplay, and its visual style. Common criticisms included the game's lack of depth, its use of unnecessary microtransactions, and its lack of an ending. The game grossed US$5.1 million (equivalent to about $5.5M in 2019) in microtransaction sales in the first two weeks after its release. While Fallout Shelter is a single-player experience, a multiplayer board game adaptation of the game was released about five years after its original release.
  • 2.5K
  • 30 Sep 2022
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