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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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IBIDA
A company's earnings before interest, taxes, depreciation, and amortization (commonly abbreviated EBITDA, pronounced /iːbɪtˈdɑː/, /əˈbɪtdɑː/, or /ˈɛbɪtdɑː/) is an accounting measure calculated using a company's earnings, before interest expenses, taxes, depreciation, and amortization are subtracted, as a proxy for a company's current operating profitability (i.e., how much profit it makes with its present assets and its operations on the products it produces and sells, as well as providing a proxy for cash flow). Though often shown on an income statement, it is not considered part of the Generally Accepted Accounting Principles (GAAP) by the SEC.
  • 9.9K
  • 08 Oct 2022
Topic Review
Vinaya
The Vinaya (Pali & Sanskrit) is the division of the Buddhist canon (Tripitaka) containing the rules and procedures that govern the Buddhist monastic community, or sangha. Three parallel Vinaya traditions remain in use by modern monastic communities: the Theravada (Sri Lanka & Southeast Asia), Mulasarvastivada (Tibetan Buddhism and the Himalayan region) and Dharmaguptaka (East Asian Buddhism). In addition to these Vinaya traditions, Vinaya texts of several extinct schools of Indian Buddhism are preserved in the Tibetan and East Asian canons, including those of the Kāśyapīya, the Mahāsāṃghika, the Mahīśāsaka, and the Sarvāstivāda The word Vinaya is derived from a Sanskrit verb that can mean to lead, take away, train, tame, or guide, or alternately to educate or teach. It is often translated as 'discipline', with Dhamma-vinaya, 'doctrine and discipline', used by the Buddha to refer to his complete teachings, suggesting its integral role in Buddhist practice.
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  • 08 Oct 2022
Topic Review
Liquid Mirror Telescope
Liquid mirror telescopes are telescopes with mirrors made with a reflective liquid. The most common liquid used is mercury, but other liquids will work as well (for example, low melting alloys of gallium). The liquid and its container are rotated at a constant speed around a vertical axis, which causes the surface of the liquid to assume a paraboloidal shape, suitable for use as the primary mirror of a reflecting telescope. The rotating liquid assumes the paraboloidal shape regardless of the container's shape. To reduce the amount of liquid metal needed, and thus weight, a rotating mercury mirror uses a container that is as close to the necessary parabolic shape as possible. Liquid mirrors can be a low cost alternative to conventional large telescopes. Compared to a solid glass mirror that must be cast, ground, and polished, a rotating liquid metal mirror is much less expensive to manufacture. Isaac Newton noted that the free surface of a rotating liquid forms a circular paraboloid and can therefore be used as a telescope, but he could not actually build one because he had no way to stabilize the speed of rotation. The concept was further developed by Ernesto Capocci of the Naples Observatory (1850), but it was not until 1872 that Henry Skey of Dunedin, New Zealand constructed the first working laboratory liquid mirror telescope. Another difficulty is that a liquid metal mirror can only be used in zenith telescopes, i.e., that look straight up, so it is not suitable for investigations where the telescope must remain pointing at the same location of inertial space (a possible exception to this rule may exist for a mercury mirror space telescope, where the effect of Earth's gravity is replaced by artificial gravity, perhaps by rotating the telescope on a very long tether, or propelling it gently forward with rockets). Only a telescope located at the North Pole or South Pole would offer a relatively static view of the sky, although the freezing point of mercury and the remoteness of the location would need to be considered. A very large telescope already exists at the South Pole, but the North Pole is located in the Arctic Ocean. The mercury mirror of the Large Zenith Telescope in Canada was the largest liquid metal mirror ever built. It had a diameter of six meters, and rotated at a rate of about 8.5 revolutions per minute. It is now decommissioned. This mirror was a test, built for $1 million but it was not suitable for astronomy because of the test site's weather. They are now planning to build a larger 8 meter liquid mirror telescope ALPACA for astronomical use and a larger project called LAMA with 66 individual 6.15 meter telescopes with a total collecting power equal to a 55 meter telescope, resolving power of a 70 meter scope.
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  • 08 Oct 2022
Topic Review
World Jewish Congress Lawsuit Against Swiss Banks
The World Jewish Congress lawsuit against Swiss banks was launched in 1995 to retrieve deposits made into Swiss banks by victims of Nazi persecution during and prior to World War II. Initiated as WJC negotiations with both the Government of Switzerland and its banks over burdensome proof-of-ownership requirements for accounts, strong support from United States politicians and leaked documents from a bank guard pressured a settlement in 1998 in a U.S. court for multiple classes of people affected by government and banking practices. As of 2015, US$1.28 billion has been disbursed for 457,100 claimants.
  • 2.0K
  • 08 Oct 2022
Topic Review
Studied Space Shuttle Variations and Derivatives
During the lifetime of NASA's Space Shuttle, Rockwell International and many other organizations studied different Space Shuttle variations and derivatives. These studies included different ways to increase shuttle payload capability, crew capacity, and developing standalone reusable launch vehicles. A large focus of the program was towards new shuttle boosters and an upgrades to the external tank but also looked to expand NASA's ability to launch deep space missions and build large modular space stations. Many of these concepts and studies would shape the concepts and programs of the 2000s such as Constellation, Orbital Space Plane Program, and Artemis program.
  • 2.2K
  • 08 Oct 2022
Topic Review
Grey Goo
Grey goo (also spelled gray goo) is a hypothetical end-of-the-world scenario involving molecular nanotechnology in which out-of-control self-replicating robots consume all biomass on Earth while building more of themselves, a scenario that has been called ecophagy ("eating the environment", more literally "eating the habitation"). The original idea assumed machines were designed to have this capability, while popularizations have assumed that machines might somehow gain this capability by accident. Self-replicating machines of the macroscopic variety were originally described by mathematician John von Neumann, and are sometimes referred to as von Neumann machines or clanking replicators. The term gray goo was coined by nanotechnology pioneer Eric Drexler in his 1986 book Engines of Creation. In 2004 he stated, "I wish I had never used the term 'gray goo'." Engines of Creation mentions "gray goo" in two paragraphs and a note, while the popularized idea of gray goo was first publicized in a mass-circulation magazine, Omni, in November 1986.
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  • 08 Oct 2022
Topic Review
Timeline of Hepatitis
This is a Timeline of hepatitis, describing major events such as epidemics and medical developments, related to hepatitis A, B, C, D and E.
  • 2.0K
  • 08 Oct 2022
Topic Review
RETRIEVE
RETRIEVE is a database management system (DBMS) offered on Tymshare's systems starting in August 1971. It was written in Tymshare's own SUPER FORTRAN on the SDS 940. It offered basic single-file, non-relational database functionality using an interactive programming language. It is one of the earliest examples of software as a service (SaaS). RETRIEVE was highly influential and spawned a number of relatively direct clones. Wang Laboratories's RECALL on the Wang 2200 minicomputer was almost identical to RETRIEVE, to the point the differences were detailed in a single page. JPL made a version known as JPLDIS for the UNIVAC 1108 in 1973 that was also very similar. Wayne Ratliff, a contractor at JPL for many years, was inspired by JPLDIS to port it to the IMSAI 8080 to manage his football pool, later releasing it commercially as Vulcan for CP/M in 1979. Ashton-Tate licensed Vulcan and re-released it as dBASE II in 1980, which sparked the microcomputer database market. Most of RETRIEVE's original syntax remains unchanged in dBASE and the many xBASE clones that survive into the 21st century.
  • 1.4K
  • 10 Oct 2022
Topic Review
Clear-channel station
A clear-channel station is an AM radio station in North America that has the highest protection from interference from other stations, particularly concerning night-time skywave propagation. The system exists to ensure the viability of cross-country or cross-continent radio service, and is enforced through a series of treaties and statutory laws. Now known as Class A stations since 1982, they are occasionally still referred to by their former classifications of Class I-A (the highest classification), Class I-B (the next highest class), or Class I-N (for stations in Alaska too far away to cause interference to the primary clear-channel stations in the lower 48 states). The term "clear-channel" is used most often in the context of North America and the Caribbean, where the concept originated. Since 1941, these stations have been required to maintain at least 10,000 watts of power to retain their status. Nearly all these stations in the United States , Canada and The Bahamas broadcast at 50,000 watts, with several clear-channel stations in Mexico going as high as 150,000 watts and XEW in Mexico City operating at 250,000 watts for over 80 years. (Cuba was originally included in the plan and had several stations given clear-channel status, but Cuba stopped participating after 1959.)
  • 4.0K
  • 08 Oct 2022
Topic Review
Windows 2.0
Windows 2.0 is an obsoleted 16-bit Microsoft Windows GUI-based operating environment that was released on December 9, 1987, and the successor to Windows 1.0. This product's family includes Windows 2.0, a base edition for 8086 real mode, and Windows/386 2.0, an enhanced edition for i386 protected mode.
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  • 08 Oct 2022
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