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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Ryu-Takayanagi Conjecture
The Ryu-Takayanagi conjecture is a conjecture within holography that posits a quantitative relationship between the entanglement entropy of a conformal field theory and the geometry of an associated Anti-de Sitter spacetime . The formula characterizes "holographic screens" in the bulk; that is, it specifies which regions of the bulk geometry are "responsible to particular information in the dual CFT". The conjecture is named after Shinsei Ryu and Tadashi Takayanagi, who jointly published the result in 2006. As a result, the authors were awarded the 2015 New Horizons in Physics Prize for "fundamental ideas about entropy in quantum field theory and quantum gravity". The formula was generalized to a covariant form in 2007.
  • 1.9K
  • 12 Oct 2022
Topic Review
Indian Regional Navigation Satellite System
The Indian Regional Navigation Satellite System (IRNSS), with an operational name of NAVIC (acronym for NAVigation with Indian Constellation; also, nāvik 'sailor' or 'navigator' in Sanskrit, Hindi, and many other Indian languages), is an autonomous regional satellite navigation system that provides accurate real-time positioning and timing services. It covers India and a region extending 1,500 km (930 mi) around it, with plans for further extension. An extended service area lies between the primary service area and a rectangle area enclosed by the 30th parallel south to the 50th parallel north and the 30th meridian east to the 130th meridian east, 1,500–6,000 km (930–3,730 mi) beyond borders. The system currently consists of a constellation of seven satellites, with two additional satellites on ground as stand-by. The constellation is in orbit as of 2018, and the system was expected to be operational from early 2018 after a system check. NAVIC will provide two levels of service, the "standard positioning service", which will be open for civilian use, and a "restricted service" (an encrypted one) for authorised users (including the military). NAVIC is planned to become available for civilian use in the first half of 2020. There are plans to expand the NAVIC system by increasing its constellation size from 7 to 11.
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  • 12 Oct 2022
Topic Review
Ms. Tree (Ship)
Ms. Tree, formerly known as Mr. Steven, and its sister ship, Ms. Chief are marine vessels chartered by SpaceX as platforms for recovery of rocket payload fairings. These ships have been retrofitted with large nets that are intended to catch fairings—to prevent the fairings from making contact with seawater—as a part of an iterative development program to create technology that will eventually allow rocket payload fairings to be economically reused and reflown. Ms. Tree was used for SpaceX Falcon 9 fairing recovery experiments on a number of occasions in 2018 and early 2019, while named Mr. Steven. The ship first successfully caught a descending fairing in its large net on June 25, 2019 during the STP-2 mission from a Falcon Heavy flight, coincidentally on its first fairing recovery voyage after the ship had been renamed Ms. Tree following a change of ownership.
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  • 12 Oct 2022
Topic Review
Food Science
Food science is the basic science and applied science of food; its scope starts at overlap with agricultural science and nutritional science and leads through the scientific aspects of food safety and food processing, informing the development of food technology. Food science brings together multiple scientific disciplines. It incorporates concepts from fields such as chemistry, physics, physiology, microbiology, and biochemistry. Food technology incorporates concepts from chemical engineering, for example. Activities of food scientists include the development of new food products, design of processes to produce these foods, choice of packaging materials, shelf-life studies, sensory evaluation of products using survey panels or potential consumers, as well as microbiological and chemical testing. Food scientists may study more fundamental phenomena that are directly linked to the production of food products and its properties.
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  • 12 Oct 2022
Topic Review
Tellurophenes
Tellurophenes are the tellurium analogue of thiophenes and selenophenes.
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  • 12 Oct 2022
Topic Review
Online Shopping
Online shopping is a form of electronic commerce which allows consumers to directly buy goods or services from a seller over the Internet using a web browser. Consumers find a product of interest by visiting the website of the retailer directly or by searching among alternative vendors using a shopping search engine, which displays the same product's availability and pricing at different e-retailers. As of 2016, customers can shop online using a range of different computers and devices, including desktop computers, laptops, tablet computers and smartphones. An online shop evokes the physical analogy of buying products or services at a regular "bricks-and-mortar" retailer or shopping center; the process is called business-to-consumer (B2C) online shopping. When an online store is set up to enable businesses to buy from another businesses, the process is called business-to-business (B2B) online shopping. A typical online store enables the customer to browse the firm's range of products and services, view photos or images of the products, along with information about the product specifications, features and prices. Online stores typically enable shoppers to use "search" features to find specific models, brands or items. Online customers must have access to the Internet and a valid method of payment in order to complete a transaction, such as a credit card, an Interac-enabled debit card, or a service such as PayPal. For physical products (e.g., paperback books or clothes), the e-tailer ships the products to the customer; for digital products, such as digital audio files of songs or software, the e-tailer typically sends the file to the customer over the Internet. The largest of these online retailing corporations are Alibaba, Amazon.com, and eBay.
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  • 12 Oct 2022
Topic Review
Seongcheol
Seongcheol (April 6, 1912 – November 4, 1993) is the dharma name of a Korean Seon (Zen) Master. He was a key figure in modern Korean Buddhism, being responsible for significant changes to it from the 1950s to 1990s. Seongcheol was widely recognized in Korea as having been a living Buddha, due to his extremely ascetic lifestyle, the duration and manner of his meditation training, his central role in reforming Korean Buddhism in the post-World War II era, and the quality of his oral and written teachings.
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  • 12 Oct 2022
Topic Review
Tethys (Database)
Tethys is an online knowledge management system that provides the marine renewable energy (MRE) and wind energy communities with access to information and scientific literature on the environmental effects of devices. Named after the Greek titaness of the sea, the goal of the Tethys database is to promote environmental stewardship and the advancement of the wind and marine renewable energy communities. The website has been developed by the Pacific Northwest National Laboratory (PNNL) in support of the U.S. Department of Energy (DOE) Wind and Water Power Technologies Office. Tethys hosts information and activities associated with two international collaborations known as OES-Environmental and WREN, formed to examine the environmental effects of marine renewable energy projects and wind energy projects, respectively.
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  • 12 Oct 2022
Topic Review
FYFT P-Series Unmanned Blimp
FYFT P-series unmanned blimps are Chinese UAVs developed by Qingdao Co., Ltd. Fei-Yu (meaning Flying Universe) Aviation Science and Technology Co., Ltd. (FYFT, 青岛飞宇有限公司), and these unmanned blimps are named after their respective length. For example: if an A1 series blimp is 11 meter long, then it is named A1-1100, because 11 meter is equal to 1100 millimeter. P-series unmanned blimps are intend for law enforcement applications, and P stands for Police. The greatest difference between P-series and other unmanned blimps for civilian use such as S-series unmanned blimps for aerial survey is that for law enforcement application, data link is added to provide real-time or near real-time transmission of information gathered so police can respond in a timely manner, as opposed to civilian versions where information is downloaded and evaluated after the UAVs have landed.
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  • 14 Oct 2022
Topic Review
Republicanism
Republicanism is a political ideology centred on citizenship in a state organized as a republic under which the people hold popular sovereignty. Many countries are "republics" in the sense that they are not monarchies. The word "republic" derives from the Latin noun-phrase res publica, which referred to the system of government that emerged in the 6th century BC following the expulsion of the kings from Rome by Lucius Junius Brutus and Collatinus. This form of government in the Roman state collapsed in the latter part of the 1st century BCE, giving way to what was a monarchy in form, if not in name. Republics re-occurred subsequently, with, for example, Renaissance Florence or early modern Britain. The concept of a republic became a powerful force in Britain's North American colonies, where it contributed to the American Revolution. In Europe, it gained enormous influence through the French Revolution and through the First French Republic of 1792–1804.
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  • 12 Oct 2022
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