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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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Ptah
In Egyptian mythology, Ptah (/pəˈtɑː/; Ancient Egyptian: ptḥ, reconstructed [piˈtaħ]; Ancient Greek:; Coptic: ⲡⲧⲁϩ) is the demiurge of Memphis, god of craftsmen and architects. In the triad of Memphis, he is the husband of Sekhmet and the father of Nefertum. He was also regarded as the father of the sage Imhotep.
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  • 22 Nov 2022
Topic Review
Sponge
Sponges, the members of the phylum Porifera (/pəˈrɪfərə/; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were first to branch off the evolutionary tree from the last common ancestor of all animals, making them the sister group of all other animals.
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  • 22 Nov 2022
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Heaviside Condition
The Heaviside condition, named for Oliver Heaviside (1850–1925), is the condition an electrical transmission line must meet in order for there to be no distortion of a transmitted signal. Also known as the distortionless condition, it can be used to improve the performance of a transmission line by adding loading to the cable.
  • 1.8K
  • 22 Nov 2022
Topic Review
Healthcare Services Specification Project
The Healthcare Services Specification Project (HSSP) is a standards development effort to create health industry service-oriented architecture (SOA) standards supportive of the health care market sector. HSSP is a jointly sponsored activity operating within the Health Level Seven (HL7) and the Object Management Group (OMG) standards group. Formally beginning as a collaboration between the HL7 Service-oriented Architecture Special Interest Group and the OMG Healthcare Domain Task Force, HSSP is developing healthcare middleware standards addressing interoperability challenges. The activity is an effort to create common “service interface specifications” that ultimately can be tractable within a Health IT context. The stated objective of the HSSP project is to create useful, usable healthcare standards that define the functions, semantics, and technology bindings supportive of system-level interoperability. To the extent possible, HSSP specifications complement existing work and standards. A key tenet to the HSSP approach is to focus on practical needs, capitalizing on open industry participation and maximizing contributions from industry talent interested in engaging.
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  • 22 Nov 2022
Topic Review
Mie–Gruneisen Equation of State
The Mie–Grüneisen equation of state is a relation between the pressure and the volume of a solid at a given temperature. It is used to determine the pressure in a shock-compressed solid. The Mie–Grüneisen relation is a special form of the Grüneisen model which describes the effect that changing the volume of a crystal lattice has on its vibrational properties. Several variations of the Mie–Grüneisen equation of state are in use. The Grüneisen model can be expressed in the form where V is the volume, p is the pressure, e is the internal energy, and Γ is the Grüneisen parameter which represents the thermal pressure from a set of vibrating atoms. If we assume that Γ is independent of p and e, we can integrate Grüneisen's model to get where p0 and e0 are the pressure and internal energy at a reference state usually assumed to be the state at which the temperature is 0K. In that case p0 and e0 are independent of temperature and the values of these quantities can be estimated from the Hugoniot equations. The Mie–Grüneisen equation of state is a special form of the above equation.
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  • 22 Nov 2022
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Poser
Poser (and Poser Pro) is a 3D computer graphics program distributed by Bondware. Poser is optimized for the 3D modeling of human figures. By enabling beginners to produce basic animations and digital images, along with the extensive availability of third-party digital 3D models, it has attained much popularity.
  • 1.8K
  • 23 Nov 2022
Topic Review
Envisat
Envisat ("Environmental Satellite") is a large inactive Earth-observing satellite which is still in orbit. Operated by the European Space Agency (ESA), it was the world's largest civilian Earth observation satellite. It was launched on 1 March 2002 aboard an Ariane 5 from the Guyana Space Centre in Kourou, French Guiana, into a Sun synchronous polar orbit at an altitude of 790 km (490 mi) (± 10 km or 6.2 mi). It orbits the Earth in about 101 minutes, with a repeat cycle of 35 days. After losing contact with the satellite on 8 April 2012, ESA formally announced the end of Envisat's mission on 9 May 2012. Envisat cost €2.3 billion (including €300 million for 5 years of operations) to develop and launch. The mission is due to be replaced by the Sentinel series of satellites. The first of these, Sentinel 1, has taken over the radar duties of Envisat since its launch in 2014.
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  • 22 Nov 2022
Topic Review
CASA C-101
The CASA C-101 Aviojet is a low-wing single engine jet-powered advanced trainer and light attack aircraft designed and manufactured by Spanish aircraft company Construcciones Aeronáuticas SA (CASA). The C-101 was developed in response to a Spanish Air Force requirement, which needed a replacement for the already outdated Hispano Saeta. During 1975, CASA commenced work on what would become the C-101. In addition to its own design team, technical assistance was provided by Germany's Messerschmitt-Bölkow-Blohm (MBB) and the United States' Northrop. During June 1977, the first of four prototypes performed the type's maiden flight. The design was somewhat reminiscent of other jet trainers of the era, such as the BAE Hawk and the Alpha Jet, but was less aerodynamically sophisticated, being equipped with an unswept wing. Performance of the C-101 during flight testing was reported in excess of predictions. On 17 March 1980, the first examples were introduced to operational service with the Spanish Air Force, which would be the principal customer for the C-101. The initial model possessed only a limited weapons capability, this attack capability was expanded upon later-built aircraft. Several models were exported to overseas operators; the C-101 has been adopted by the Chilean Air Force , Honduran Air Force and the Royal Jordanian Air Force . A final improved model, designated C-101DD, was demonstrated but did not find customers and thus it did not enter serial production. In addition to its use as a trainer aircraft, it has been used to perform aerobatics; in the latter context, it has been flown by the Patrulla Aguila aerobatics team. As of 2019, the C-101 remains in service in the Spanish Air Force and several other countries. Early on the 2010s there were talks about the replacement of the C-101. Finally, in 2020 it was decided that the C-101 would be replaced by the Pilatus PC-21 (24) and the Airbus Future Jet Trainer (50 - 55).
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  • 22 Nov 2022
Topic Review
Soyuz 1
Soyuz 1 (Russian: Союз 1, Union 1) was a crewed spaceflight of the Soviet space program. Launched into orbit on 23 April 1967 carrying cosmonaut colonel Vladimir Komarov, Soyuz 1 was the first crewed flight of the Soyuz spacecraft. The flight was plagued with technical issues, and Komarov was killed when the descent module crashed into the ground due to a parachute failure. This was the first in-flight fatality in the history of spaceflight. The original mission plan was complex, involving a rendezvous with Soyuz 2 and an exchange of crew members before returning to Earth. However, the launch of Soyuz 2 was called off due to thunderstorms.
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  • 22 Nov 2022
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Red Queen Hypothesis
The Red Queen hypothesis is a hypothesis in evolutionary biology proposed in 1973, that species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species. The hypothesis was intended to explain the constant (age-independent) extinction probability as observed in the paleontological record caused by co-evolution between competing species; however, it has also been suggested that the Red Queen hypothesis explains the advantage of sexual reproduction (as opposed to asexual reproduction) at the level of individuals, and the positive correlation between speciation and extinction rates in most higher taxa.
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  • 22 Nov 2022
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