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24,635,433 | https://en.wikipedia.org/wiki/Balanced%20Boolean%20function | In mathematics and computer science, a balanced Boolean function is a Boolean function whose output yields as many 0s as 1s over its input set. This means that for a uniformly random input string of bits, the probability of getting a 1 is 1/2.
Examples
Examples of balanced Boolean functions are the majority function, the "dictatorship function" that copies the first bit of its input to the output, and the parity check function that produces the exclusive or of the input bits.
If is a bent function on bits, and is any nonzero vector of bits, then the function that maps to is balanced. The bent functions are exactly the functions for which this is true, for all nonzero choices of .
The dictatorship function can be evaluated after examining only a single bit of the input, but that bit must always be examined. Benjamini, Schramm, and Wilson describe a more complex example based on percolation theory with the property that a randomized Las Vegas algorithm can compute the function exactly while ensuring that the probability of reading any particular input bit is small, roughly inversely proportional to the square root of the number of bits.
Application
Balanced Boolean functions are used in cryptography, where being balanced is one of "the most important criteria for cryptographically strong Boolean functions". If a function is not balanced, it will have a statistical bias, making it subject to cryptanalysis such as the correlation attack.
References
Boolean algebra | Balanced Boolean function | Mathematics | 298 |
3,955,450 | https://en.wikipedia.org/wiki/Neutral%20current | Weak neutral current interactions are one of the ways in which subatomic particles can interact by means of the weak force. These interactions are mediated by the Z boson. The discovery of weak neutral currents was a significant step toward the unification of electromagnetism and the weak force into the electroweak force, and led to the discovery of the W and Z bosons.
In simple terms
The weak force is best known for its role in nuclear decay. It has very short range but (apart from gravity) is the only force to interact with neutrinos. Like other subatomic forces, the weak force is mediated via exchange particles. Perhaps the most well known of the exchange particles for the weak force is the W particle which is involved in beta decay. W particles have electric charge – there are both positive and negative W particles – however the Z boson is also an exchange particle for the weak force but does not have any electrical charge.
Exchange of a Z boson transfers momentum, spin, and energy, but leaves the interacting particles' quantum numbers unaffected – charge, flavor, baryon number, lepton number, etc. Because there is no transfer of electrical charge involved, exchange of Z particles is referred to as "neutral" in the phrase "neutral current". However the word "current" here has nothing to do with electricity – it simply refers to the exchange of the Z particle.
The Z boson's neutral current interaction is determined by a derived quantum number called weak charge, which acts similarly to weak isospin for interactions with the W bosons.
Definition
The neutral current that gives the interaction its name is that of the interacting particles.
For example, the neutral current contribution to the → elastic scattering amplitude is
where the neutral currents describing the flow of the neutrino and of the electron are given by:
where:
and are the vector and axial couplings for fermion denotes the weak isospin of the fermions, their electric charge and their weak charge. These couplings amount to essentially left chiral for neutrinos and axial for charged leptons.
The Z boson can couple to any Standard Model particle, except gluons and photons (sterile neutrinos would also be an exception, if they were found to exist). However, any interaction between two charged particles that can occur via the exchange of a virtual Z boson can also occur via the exchange of a virtual photon. Unless the interacting particles have energies on the order of the Z boson mass (91 GeV) or higher, the virtual Z boson exchange has an effect of a tiny correction, to the amplitude of the electromagnetic process.
Particle accelerators with energies necessary to observe neutral current interactions and to measure the mass of Z boson weren't available until 1983.
On the other hand, Z boson interactions involving neutrinos have distinctive signatures: They provide the only known mechanism for elastic scattering of neutrinos in matter; neutrinos are almost as likely to scatter elastically (via Z boson exchange) as inelastically (via W boson exchange), of major experimental significance, in, e.g. , the Sudbury Neutrino Observatory experiment.
Weak neutral currents were predicted by electroweak theory developed mainly by Abdus Salam, John Clive Ward, Sheldon Glashow and Steven Weinberg, and confirmed shortly thereafter in 1973, in a neutrino experiment in the Gargamelle bubble chamber at CERN.
See also
Charged current
Flavor changing neutral current
Neutral particle oscillation
Electric current
Quantum chromodynamics
Sudbury Neutrino Observatory#Neutral current interaction
Weak charge
References
External links
Electroweak theory | Neutral current | Physics | 754 |
35,508,471 | https://en.wikipedia.org/wiki/800%20MHz%20frequency%20band | The 800 MHz frequency band is a portion of the electromagnetic spectrum, or frequency band, that encompasses 790–862 MHz.
Being a part of the spectrum known as "UHF Bands IV and V" (i.e. 470 MHz to 862 MHz) it was allocated by the ITU to Broadcasting as the primary user in Region 1 and was used for analogue television broadcasting before changing to digital terrestrial television in many countries. As such it is also referred to as "digital dividend" spectrum. In Europe and to some extent elsewhere, the band corresponds to UHF channel 61–69. In most territories the band was also used by Services Ancillary to Broadcasting (SAB) or Services Ancillary to Programme Making (SAP), both often now referred to as PMSE (Programme Making and Special Events) in the form of professional wireless microphones, radio talkback systems and wireless monitor systems.
The European Parliament approved in May 2010, and Japan in 2012, the change of use of the 800 MHz band making it available for purposes other than broadcasting (television) – e.g. mobile broadband.
From the year 2013 the 800 MHz band can be used to deliver wireless broadband services, in Europe.
Possible interference problems
Some claim that there have not been enough interference studies made in the EU.
The reason for the interference problem is that the RF chain in TV-equipment is designed to receive 470–862 MHz (EU channels 21–69) and therefore includes the range of frequencies which the new services are, or will be, using. Most TV receiving equipment in current use and currently on the market was not designed with the expectation that there would be anything but TV signals in the frequency range 470 MHz to 862 MHz. Due to the very limited guard band between the new services and the existing TV services in some cases the LTE 800 base station signals may cause interference to DTT particularly in EU channels 59 and 60.
Strong LTE base station signals in 800 MHz band, may cause limiting or clipping, that is due to overdrive in antenna amplifiers and/or DTT tuners in e.g. flat panels, set top boxes, USB-tuners and digital video recorders.
Depending on the dynamic range performance of the affected receiving equipment, the following may happen:
When forward error correction (FEC) is adequate, the TV reception will be unaffected
If the interference is sufficiently severe such that FEC cannot correct all of the errors, there will be pixelation in the picture and/or there will be sound drop-outs.
In severe cases of interference the error correction will not cope at all and this will result in a black TV-screen and / or complete loss of sound.
Overload in the RF chain will not only affect one TV channel. All signals passing through the overloaded device will be affected for as long as the device remains overloaded.
Essentially there are two types of interference sources in the 800 MHz band: The LTE base stations and the mobile terminals — handsets, tablets, dongles — which are sometimes close to TV equipment. Although the base stations may be relatively far away from the TV equipment they may be adjacent to the TV antenna, or if further away they may be in the 'beam' of the TV antenna, i.e. in the direction which the TV antenna points, and considerably closer than the TV transmitter which it is desired to receive resulting in a high level of interfering signal in the TV system. In the case of apartments, hotels, schools, colleges, offices, etc. with communal TV antenna systems the base station may be very close indeed, even on the same roof.
For the time being there are not many terminals in the European market that use the LTE 800 frequency band but this is increasing rapidly.
In the UK an organisation (Digital Mobile Spectrum Limited (DMSL), known as "at800") was set up specifically to mitigate any interference from the new LTE 800 services to TV reception in the UK.
"Channel 70" interference
The frequency band between 862 MHz to 870 MHz, or a subset of this band, e.g. 863 MHz to 865 MHz, is sometimes referred to as 'Channel 70'. 862 MHz to 870 MHz is itself divided into many smaller sub-bands used in many territories by vast numbers of a wide range of different low power radio devices, often on a licence exempt basis. For example, 863 MHz to 865 MHz is used in many European countries by cordless audio devices such as some cordless headphones, assistive listening devices (used by the hard of hearing) and some wireless microphones.
Any low power radio devices operating in the range 862 MHz to 870 MHz are most likely to be affected by interference from the portable devices using the 800 MHz LTE system since they will be transmitting in the upper part of the 790 MHz to 862 MHz band, i.e. the part of the band which is closest to the frequencies used by Low Power Radio Devices.
868 MHz interference
Systems that use the 868 MHz-band (868–870 MHz), for example, thermostats, fire systems, burglar systems, and DIN-transceivers may have difficulty communicating when there is a strong 800 MHz broadband transmitter nearby.
Notes
References
External links
ofcom.org.uk: Digital dividend: clearing the 800 MHz band
at800: The Problem with 4G LTE 800 and Freeview
Radio spectrum
Radio technology | 800 MHz frequency band | Physics,Technology,Engineering | 1,117 |
20,845,760 | https://en.wikipedia.org/wiki/Eilat%20stone | Eilat Stone () is a gemstone that derives its name from the city of Eilat in Israel, where it was once mined. It is characterized by a green-blue heterogeneous mixture of several secondary copper minerals, including malachite, azurite, turquoise, pseudomalachite, and chrysocolla. Eilat stone is the national stone of Israel, and is also known as the King Solomon Stone.
References
Geology of Israel
Stones
Solomon
National symbols of Israel
Eilat
Copper minerals | Eilat stone | Physics | 109 |
61,045,899 | https://en.wikipedia.org/wiki/Slimicide | Slimicide (or antislime agent) is a broad-spectrum antimicrobial pesticide used to kill slime-producing microorganisms such as algae, bacteria, fungi, and slime molds. One primary application domain is in the papermaking industry, where it reduces the occurrence of paper holes and spots, as well as protecting the machinery from odor, clogs, corrosion, and breakdown. Slimicides come in variants effective in acidic and/or alkaline media, in liquid or solid form, and are based on chemicals such as aldehydes, bromium or quaternary ammonium compounds, and others. Additional significant application areas for slimicides include industrial water recirculation systems such as cooling towers, fuel storage tanks and wells, and in conjunction with fluids used for oil extraction. In some application domains, slimicides may be formulated specifically to target slime molds.
References
Pesticides | Slimicide | Biology,Environmental_science | 191 |
54,152,714 | https://en.wikipedia.org/wiki/6-%28Methylsulfinyl%29hexyl%20isothiocyanate | 6-(Methylsulfinyl)hexyl isothiocyanate (6-MITC or 6-MSITC) is a compound within the isothiocyanate group of organosulfur compounds. 6-MITC is obtained from cruciferous vegetables, chiefly wasabi. Like other isothiocyanates, it is produced when the enzyme myrosinase transforms the associated glucosinolate into 6-MITC upon cell injury.
It is a trend in Japan to apply freshly grated wasabi stem to the hair because Kinin Corporation, the world's largest wasabi producer, claims that 6-MITC promotes hair regrowth.
In a 2023 study of healthy older adults aged 60 years and over, the group taking one tablet (0.8 mg of 6-MSITC) every day for 12 weeks showed a significant improvement in working and episodic memory performances. These results have been reported in the popular press, using the name "hexaraphane" for 6-MSITC.
See also
Methyl isothiocyanate
References
Isothiocyanates
Sulfoxides | 6-(Methylsulfinyl)hexyl isothiocyanate | Chemistry,Biology | 236 |
2,334,511 | https://en.wikipedia.org/wiki/What%20Is%20Life%3F | What Is Life? The Physical Aspect of the Living Cell is a 1944 science book written for the lay reader by the physicist Erwin Schrödinger. The book was based on a course of public lectures delivered by Schrödinger in February1943, under the auspices of the Dublin Institute for Advanced Studies, where he was Director of Theoretical Physics, at Trinity College, Dublin. The lectures attracted an audience of about 400, who were warned "that the subject-matter was a difficult one and that the lectures could not be termed popular, even though the physicist’s most dreaded weapon, mathematical deduction, would hardly be utilized." Schrödinger's lecture focused on one important question: "how can the events in space and time which take place within the spatial boundary of a living organism be accounted for by physics and chemistry?"
In the book, Schrödinger introduced the idea of an "aperiodic solid" that contained genetic information in its configuration of covalent chemical bonds. In the 1940s, this idea stimulated enthusiasm for discovering the chemical basis of genetic inheritance. Although the existence of some form of hereditary information had been hypothesized since 1869, its role in reproduction and its helical shape were still unknown at the time of Schrödinger's lecture. In 1953, James D. Watson and Francis Crick jointly proposed the double helix structure of deoxyribonucleic acid (DNA) on the basis of, amongst other theoretical insights, X-ray diffraction experiments conducted by Rosalind Franklin. They both credited Schrödinger's book with presenting an early theoretical description of how the storage of genetic information would work, and each independently acknowledged the book as a source of inspiration for their initial researches.
Background
The book, published in 1944, is based on lectures delivered under the auspices of the Dublin Institute for Advanced Studies at Trinity College, Dublin in February 1943, attended by Éamon de Valera and his cabinet. At that time, although DNA was known to be a constituent of cell nuclei, it had not yet been identified with certainty as the molecular basis of inheritance, and the concept of a "heredity molecule" was strictly theoretical, with various candidates. One of the most successful branches of physics at this time was statistical physics. Schrödinger himself is one of the founding fathers of quantum mechanics, a theory which posits a statistical focus for understanding the natural world at subatomic scale.
Max Delbrück's thinking about the physical basis of life was an important influence on Schrödinger. However, long before the publication of What is Life?, the American geneticist Hermann J. Muller, who would later win a Nobel Prize in 1946, had in his 1922 article "Variation due to Change in the Individual Gene" already laid out all the basic properties of the "heredity molecule" (not yet known to be DNA) which Schrödinger re-derived in 1944 "from first principles" in What is Life? (including the "aperiodicity" of the molecule), properties which Muller specified and refined additionally in his 1929 article "The Gene As The Basis of Life" and during the 1930s. Muller himself wrote in a 1960 letter to a journalist regarding What Is Life? that whatever the book got right about the "hereditary molecule" had already been published before 1944 and that Schrödinger's were only the wrong speculations; Muller also named two famous geneticists, including Delbrück, who knew every relevant pre-1944 publication and had been in contact with Schrödinger before 1944. DNA as the molecule of heredity became foremost only after Oswald Avery's bacterial-transformation experiments published in 1944; before those experiments, proteins were considered the most likely candidates. DNA was confirmed as the molecule in question by the
Hershey–Chase experiment conducted in 1952.
Content
In Chapter I, Schrödinger explains that most physical laws on a large scale are due to chaos on a small scale. He calls this principle "order-from-disorder". As an example he mentions diffusion, which can be modeled as a highly ordered process, but which is nevertheless caused by random movement of atoms or molecules. As the number of atoms is reduced, the behaviour of a system becomes increasingly random. He states that life greatly depends on order and that a naïve physicist may assume that the master code of a living organism has to consist of a large number of atoms.
In Chapter II and III, he summarizes what was known at the time about the hereditary mechanism. Most importantly, he elaborates on the role mutations play in biological evolution. He concludes that the carrier of hereditary information has to be both small in size and permanent in time, contradicting the naïve physicist's expectation. This contradiction cannot be resolved by classical physics.
In Chapter IV, Schrödinger presents molecules, which are indeed stable even if they consist of only a few atoms, as the solution. Even though molecules had long been known to exist, their stability could not be explained by classical physics due to the discrete nature of quantum mechanics. Furthermore, mutations are directly linked to quantum leaps.
He continues to explain, in chapter V, that true solids, which are also permanent, are composed of highly ordered crystals. The stability of molecules and crystals is due to the same principles, and a molecule might be called "the germ of a solid". On the other hand, an amorphous solid, without crystalline structure, should be regarded as a liquid with a very high viscosity. Schrödinger writes that the heredity material is likely to be a molecule, which unlike a crystal does not repeat itself. He calls this an "aperiodic crystal". Its aperiodic nature allows it to encode an almost infinite number of possibilities with a small number of atoms. He finally compares this picture with the known facts and finds it in accordance with them.
In Chapter VI, Schrödinger states:
...living matter, while not eluding the "laws of physics" as established up to date, is likely to involve "other laws of physics" hitherto unknown, which however, once they have been revealed, will form just as integral a part of science as the former.
He anticipates that this statement will be open to misconception and tries to clarify it. The main principle involved with "order-from-disorder" is the second law of thermodynamics, according to which entropy only increases in a closed system (such as the universe). Schrödinger explains that living matter evades the decay to thermodynamical equilibrium by homeostatically maintaining negative entropy in an open system.
In Chapter VII, he maintains that "order-from-order" is not absolutely new to physics; in fact, it is even simpler and more plausible. But nature follows "order-from-disorder", with such exceptions as the predictable movement of the celestial bodies and the behaviour of mechanical devices such as clocks. Even those are influenced by thermal and frictional forces. The degree to which a system functions mechanically or randomly depends on the temperature. If sufficiently heated, a clock melts into a puddle of randomly moving molecules. Conversely, if the temperature approaches absolute zero, any system behaves more and more mechanically. Some systems, such as clocks, approach this mechanical behaviour even at room temperature.
Schrödinger concludes this chapter and the book with philosophical speculations on determinism, free will, and the mystery of human consciousness. He attempts to "see whether we cannot draw the correct non-contradictory conclusion from the following two premises: (1) My body functions as a pure mechanism according to Laws of Nature; and (2) Yet I know, by incontrovertible direct experience, that I am directing its motions, of which I foresee the effects, that may be fateful and all-important, in which case I feel and take full responsibility for them. The only possible inference from these two facts is, I think, that I – I in the widest meaning of the word, that is to say, every conscious mind that has ever said or felt 'I' – am the person, if any, who controls the 'motion of the atoms' according to the Laws of Nature". Schrödinger then states that this insight is not new and that the Upanishads considered this insight of "ATMAN = BRAHMAN" to "represent quintessence of deepest insights into the happenings of the world." Schrödinger rejects the idea that the source of consciousness should perish with the body because he finds the idea "distasteful". He also rejects the idea that there are multiple immortal souls that can exist without the body because he believes that consciousness is nevertheless highly dependent on the body. Schrödinger writes that, to reconcile the two premises,"The only possible alternative is simply to keep to the immediate experience that consciousness is a singular of which the plural is unknown; that there is only one thing and that what seems to be a plurality is merely a series of different aspects of this one thing…:
Any intuitions that consciousness is plural, he says, are illusions. Schrödinger is sympathetic to the Hindu concept of Brahman, by which each individual's consciousness is only a manifestation of a unitary consciousness pervading the universe — which corresponds to the Hindu concept of God. Schrödinger concludes that "...'I' am the person, if any, who controls the 'motion of the atoms' according to the Laws of Nature." However, he also qualifies the conclusion as "necessarily subjective" in its "philosophical implications". In the final paragraph, he points out that what is meant by "I" is not the collection of experienced events but "namely the canvas upon which they are collected." If a hypnotist succeeds in blotting out all earlier reminiscences, he writes, there would be no loss of personal existence — "Nor will there ever be."
Schrödinger's "paradox"
In a world governed by the second law of thermodynamics, all isolated systems are expected to approach a state of maximum disorder or entropy: an irreversible state of thermodynamic equilibrium, where free energy is no longer available to do work. It has been argued that, since life approaches and maintains a highly ordered state, it violates the aforementioned second law, implying that there is a paradox. However, since the biosphere is not an isolated system, there is no paradox. The increase of order inside an organism is more than paid for by an increase in disorder outside this organism by the loss of heat into the environment. By this mechanism, the second law is obeyed, and life maintains a highly ordered state, which it sustains by causing a net increase in disorder in the Universe. In order to increase the complexity on Earth—as life does—free energy is needed, and in this case is provided by the Sun.
Editions
Erwin Schrödinger (1944), What Is Life? and Other Scientific Essays. Based on lectures delivered under the auspices of the Dublin Institute for Advanced Studies at Trinity College, Dublin, in February 1943. Doubleday (1956) and Internet Archive.
See also
Entropy and life
Gibbs free energy
James D. Watson
Quantum Aspects of Life
Philosophy of biology
References
External links
Österr. Zentralbibliothek für Physik Scan of the title and first part of the contents
Critical interdisciplinary review of Schrödinger's "What Is life?"
Schrödinger's influence on biology
Biophysics
Erwin Schrödinger
Biology books
Mathematical and theoretical biology
Cognitive science literature
1944 non-fiction books
1944 in biology
Dichotomies
Cambridge University Press books
History of genetics
Philosophy of biology
Determinism
Contemporary philosophical literature
Quantum biology
Popular science books
Physics books | What Is Life? | Physics,Mathematics,Biology | 2,438 |
41,609,009 | https://en.wikipedia.org/wiki/26%20Cygni | 26 Cygni is a single star in the northern constellation of Cygnus. It has the Bayer designation e Cygni, while 26 Cygni is the Flamsteed designation. This star is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 5.12. It is located around distant from the Sun, based on parallax measurements. The radial velocity is close to negligible, being measured at −0.3 km/s.
This object is an evolved giant star with a stellar classification of G8 III; a star that has used up its core hydrogen and left the main sequence. It is most likely (88% chance) on the horizontal branch, in which case stellar modelling yields an estimated 2.44 times the mass of the Sun and 22 times the Sun's radius. It is radiating 205 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,700 K.
There is a magnitude 8.94 visual companion at an angular separation of along a position angle of 150°, as of 2014.
References
G-type giants
Horizontal-branch stars
Double stars
Cygnus (constellation)
J20012157+5006167
Cygni, e
Cygni, 26
BD+49 3158
190147
098571
7660 | 26 Cygni | Astronomy | 279 |
5,095,008 | https://en.wikipedia.org/wiki/Sigma%20Cassiopeiae | [[File:SigCasLightCurve.png|thumb|left|Light curves for Sigma Cassiopeiae, plotted from TESS data.]]
Sigma Cassiopeiae (σ Cas, σ Cassiopeiae) is a binary star in the constellation Cassiopeia. It is 1,200 to from Earth and has a combined apparent magnitude of +4.88, making it visible to the naked eye.
The primary component, σ Cassiopeiae A, is a B2 subgiant with an apparent magnitude of +5.0. Its companion, σ Cassiopeiae B, is a B5 main sequence dwarf with an apparent magnitude of +7.1. The two stars are three arcseconds apart.
Naming
In Chinese, (), meaning Flying Serpent'', refers to an asterism consisting of σ Cassiopeiae, α Lacertae, 4 Lacertae, π2 Cygni, π1 Cygni, HD 206267, ε Cephei, β Lacertae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, λ Andromedae, κ Andromedae, ι Andromedae, and ψ Andromedae. Consequently, the Chinese name for σ Cassiopeiae itself is (, ).
References
Cassiopeiae, Sigma
Cassiopeiae, 08
Binary stars
B-type giants
B-type main-sequence stars
Cassiopeia (constellation)
9071
224572
118243
Durchmusterung objects
Beta Cephei variables
Suspected variables | Sigma Cassiopeiae | Astronomy | 358 |
14,356,754 | https://en.wikipedia.org/wiki/Hatta%20number | The Hatta number (Ha) was developed by Shirôji Hatta (1895-1973 ) in 1932, who taught at Tohoku University from 1925 to 1958. It is a dimensionless parameter that compares the rate of reaction in a liquid film to the rate of diffusion through the film. For a second order reaction (), the maximum rate of reaction assumes that the liquid film is saturated with gas at the interfacial concentration ; thus, the maximum rate of reaction is .
For a reaction order in and order in :
For gas-liquid absorption with chemical reactions, a high Hatta number indicates the reaction is much faster than diffusion. In this case, the reaction occurs within a thin film, and the surface area limits the overall rate. Conversely, a Hatta number smaller than unity suggests the reaction is the limiting factor, and the reaction takes place in the bulk fluid, requiring larger volumes.
References
See also
Dimensionless quantity
Dimensional analysis
Catalysis
Dimensionless numbers of chemistry
Transport phenomena | Hatta number | Physics,Chemistry,Engineering | 202 |
11,127,883 | https://en.wikipedia.org/wiki/Helicobasidium%20longisporum | Helicobasidium longisporum is a species of fungus in the subdivision Pucciniomycotina. Basidiocarps (fruit bodies) are corticioid (patch-forming) and are typically violet to purple. Microscopically they have auricularioid (laterally septate) basidia. Helicobasidium longisporum is an opportunistic plant pathogen and is one of the causes of violet root rot of crops and other plants. DNA sequencing suggests that it is a complex of more than one species.
Taxonomy
Helicobasidium longisporum was first described from Uganda in 1917 by British mycologist Elsie Wakefield to accommodate a species similar to Helicobasidium purpureum but with elongated basidiospores. It was found parasitizing roots of cocoa (Theobroma cacao). A similarly long-spored Japanese taxon was described as H. mompa f. macrosporum and a further long-spored species was subsequently described from Indonesia as H. compactum. All three were considered conspecific in a 1999 study.
In 1955 Japanese mycologist Seiya Ito synonymized H. mompa f. macrosporum and H. compactum with a short-spored species, Helicobasidium mompa. As a result, at least some subsequent references to H. mompa refer to a long—spored species.
Initial molecular research, based on cladistic analysis of DNA sequences, indicates that at least two species occur in the H.longisporum complex, one in Europe (together with its Tuberculina anamorph) and one in Africa and the Americas (also with its anamorph).
Description
Basidiocarps are corticioid smooth, membranaceous, purple to purple-brown. Microscopically the hyphae are easily visible, 5–8 μm diam., brownish-purple, and lack clamp connections. Basidia are tubular, curved or crook-shaped, and auricularioid (laterally septate). Basidiospores are elongated clavate, mostly 16–25 x 4.5–6 μm.
Distribution
Helicobasidium longisporum has been recorded from both temperate and tropical areas of Africa, America, Asia, Australia, and Europe. It is reported to cause violet root rot of various crops and a similar collar rot or collar canker of coffee trees.
References
Fungal plant pathogens and diseases
Fungi described in 1917
Fungi of Africa
Pucciniomycotina
Fungus species | Helicobasidium longisporum | Biology | 540 |
1,449,980 | https://en.wikipedia.org/wiki/Jason%20%28rocket%29 | Jason was an American sounding rocket with 5 stages. The Jason was launched 22 times in 1958. The Jason could carry a payload of 125 pounds (57 kg) to an altitude of 500 mi (800 km). The launch thrust was 82,100 pounds-force (365 kN), the launch mass 7,340 lb (3330 kg), the diameter 58 centimeters (23 in) and the length 17.5 meters (57 ft).
Also known as Argo E-5, this research vehicle was made by Aerolab for the Air Force (AFSWC) for use in the Jason program, which measured the trapped radiation from the Argus nuclear tests in the latter half of 1958. It was launched from Cape Kennedy, Wallops, and Puerto Rico. It consisted of an Honest John first stage plus a Nike stage plus another Nike stage plus a Recruit stage plus a T-55 as the fifth stage.
References
External links
NASA History Office
Sounding rockets of the United States
1958 in spaceflight | Jason (rocket) | Astronomy | 203 |
68,990,413 | https://en.wikipedia.org/wiki/Hardware%20for%20artificial%20intelligence | Specialized computer hardware is often used to execute artificial intelligence (AI) programs faster, and with less energy, such as Lisp machines, neuromorphic engineering, event cameras, and physical neural networks. Since 2017, several consumer grade CPUs and SoCs have on-die NPUs. As of 2023, the market for AI hardware is dominated by GPUs.
Lisp machines
Lisp machines were developed in the late 1970s and early 1980s to make Artificial intelligence programs written in the programming language Lisp run faster.
Dataflow architecture
Dataflow architecture processors used for AI serve various purposes, with varied implementations like the polymorphic dataflow Convolution Engine by Kinara (formerly Deep Vision), structure-driven dataflow by Hailo, and dataflow scheduling by Cerebras.
Component hardware
AI accelerators
Since the 2010s, advances in computer hardware have led to more efficient methods for training deep neural networks that contain many layers of non-linear hidden units and a very large output layer. By 2019, graphics processing units (GPUs), often with AI-specific enhancements, had displaced central processing units (CPUs) as the dominant means to train large-scale commercial cloud AI. OpenAI estimated the hardware compute used in the largest deep learning projects from Alex Net (2012) to Alpha Zero (2017), and found a 300,000-fold increase in the amount of compute needed, with a doubling-time trend of 3.4 months.
Sources
Computer hardware
Artificial intelligence | Hardware for artificial intelligence | Technology,Engineering | 303 |
38,458 | https://en.wikipedia.org/wiki/Space%20Shuttle%20program | The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. Its official program name was Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft where it was the only item funded for development, as a proposed nuclear shuttle in the plan was cancelled in 1972. It flew 135 missions and carried 355 astronauts from 16 countries, many on multiple trips.
The Space Shuttle, composed of an orbiter launched with two reusable solid rocket boosters and a disposable external fuel tank, carried up to eight astronauts and up to of payload into low Earth orbit (LEO). When its mission was complete, the orbiter would reenter the Earth's atmosphere and land like a glider at either the Kennedy Space Center or Edwards Air Force Base.
The Shuttle is the only winged crewed spacecraft to have achieved orbit and landing, and the first reusable crewed space vehicle that made multiple flights into orbit. Its missions involved carrying large payloads to various orbits including the International Space Station (ISS), providing crew rotation for the space station, and performing service missions on the Hubble Space Telescope. The orbiter also recovered satellites and other payloads (e.g., from the ISS) from orbit and returned them to Earth, though its use in this capacity was rare. Each vehicle was designed with a projected lifespan of 100 launches, or 10 years' operational life. Original selling points on the shuttles were over 150 launches over a 15-year operational span with a 'launch per month' expected at the peak of the program, but extensive delays in the development of the International Space Station never created such a peak demand for frequent flights.
Background
Various shuttle concepts had been explored since the late 1960s. The program formally commenced in 1972, becoming the sole focus of NASA's human spaceflight operations after the Apollo, Skylab, and Apollo–Soyuz programs in 1975. The Shuttle was originally conceived of and presented to the public in 1972 as a 'Space Truck' which would, among other things, be used to build a United States space station in low Earth orbit during the 1980s and then be replaced by a new vehicle by the early 1990s. The stalled plans for a U.S. space station evolved into the International Space Station and were formally initiated in 1983 by President Ronald Reagan, but the ISS suffered from long delays, design changes and cost over-runs and forced the service life of the Space Shuttle to be extended several times until 2011 when it was finally retired—serving twice as long as it was originally designed to do. In 2004, according to President George W. Bush's Vision for Space Exploration, use of the Space Shuttle was to be focused almost exclusively on completing assembly of the ISS, which was far behind schedule at that point.
The first experimental orbiter, Enterprise, was a high-altitude glider, launched from the back of a specially modified Boeing 747, only for initial atmospheric landing tests (ALT). Enterprises first test flight was on February 18, 1977, only five years after the Shuttle program was formally initiated; leading to the launch of the first space-worthy shuttle Columbia on April 12, 1981, on STS-1. The Space Shuttle program finished with its last mission, STS-135 flown by Atlantis, in July 2011, retiring the final Shuttle in the fleet. The Space Shuttle program formally ended on August 31, 2011.
Conception and development
Program history
All Space Shuttle missions were launched from the Kennedy Space Center (KSC) in Florida. Some civilian and military circumpolar space shuttle missions were planned for Vandenberg AFB in California. However, the use of Vandenberg AFB for space shuttle missions was canceled after the Challenger disaster in 1986. The weather criteria used for launch included, but were not limited to: precipitation, temperatures, cloud cover, lightning forecast, wind, and humidity. The Shuttle was not launched under conditions where it could have been struck by lightning.
The first fully functional orbiter was Columbia (designated OV-102), built in Palmdale, California. It was delivered to Kennedy Space Center (KSC) on March 25, 1979, and was first launched on April 12, 1981—the 20th anniversary of Yuri Gagarin's space flight—with a crew of two.
Challenger (OV-099) was delivered to KSC in July 1982, Discovery (OV-103) in November 1983, Atlantis (OV-104) in April 1985 and Endeavour (OV-105) in May 1991. Challenger was originally built and used as a Structural Test Article (STA-099), but was converted to a complete orbiter when this was found to be less expensive than converting Enterprise from its Approach and Landing Test configuration into a spaceworthy vehicle.
On April 24, 1990, Discovery carried the Hubble Space Telescope into space during STS-31.
In the course of 135 missions flown, two orbiters (Columbia and Challenger) suffered catastrophic accidents, with the loss of all crew members, totaling 14 astronauts.
The accidents led to national level inquiries, detailed analysis of why the accidents occurred, and significant pauses where changes were made before the Shuttles returned to flight. After the Challenger disaster in January 1986, there was a delay of 32 months before the next Shuttle launch. A similar delay of 29 months occurred after the Columbia disaster in February 2003.
The longest Shuttle mission was STS-80 lasting 17 days, 15 hours. The final flight of the Space Shuttle program was STS-135 on July 8, 2011.
Since the Shuttle's retirement in 2011, many of its original duties are performed by an assortment of government and private vessels. The European ATV Automated Transfer Vehicle supplied the ISS between 2008 and 2015. Classified military missions are being flown by the US Air Force's uncrewed spaceplane, the X-37B. By 2012, cargo to the International Space Station was already being delivered commercially under NASA's Commercial Resupply Services by SpaceX's partially reusable Dragon spacecraft, followed by Orbital Sciences' Cygnus spacecraft in late 2013. Crew service to the ISS is currently provided by the Russian Soyuz and, since 2020, the SpaceX Dragon 2 crew capsule, launched on the company's reusable Falcon 9 rocket as part of NASA's Commercial Crew Development program. Boeing's Starliner capsule is scheduled to start ISS crew service from 2025. For missions beyond low Earth orbit, NASA is building the Space Launch System and the Orion spacecraft, part of the Artemis program.
Accomplishments
Space Shuttle missions have included:
Spacelab missions Including:
Science
Astronomy
Crystal growth
Space physics
Construction of the International Space Station (ISS)
Crew rotation and servicing of Mir and the International Space Station (ISS)
Servicing missions, such as to repair the Hubble Space Telescope (HST) and orbiting satellites
Human experiments in low Earth orbit (LEO)
Carried to low Earth orbit (LEO):
The Hubble Space Telescope (HST)
Components of the International Space Station (ISS)
Supplies in Spacehab modules or Multi-Purpose Logistics Modules
The Long Duration Exposure Facility
The Upper Atmosphere Research Satellite
The Compton Gamma Ray Observatory
The Earth Radiation Budget Satellite
The Mir Shuttle Docking Node
Carried satellites with a booster, such as the Payload Assist Module (PAM-D) or the Inertial Upper Stage (IUS), to the point where the booster sends the satellite to:
A higher Earth orbit; these have included:
Chandra X-ray Observatory
The first six TDRS satellites
Two DSCS-III (Defense Satellite Communications System) communications satellites in one mission
A Defense Support Program satellite
An interplanetary mission; these have included:
Magellan
Galileo
Ulysses
Budget
Early during development of the Space Shuttle, NASA had estimated that the program would cost $7.45 billion ($43 billion in 2011 dollars, adjusting for inflation) in development/non-recurring costs, and $9.3M ($54M in 2011 dollars) per flight. Early estimates for the cost to deliver payload to low-Earth orbit were as low as $118 per pound ($260/kg) of payload ($635/lb or $1,400/kg in 2011 dollars), based on marginal or incremental launch costs, and assuming a 65,000 pound (30 000 kg) payload capacity and 50 launches per year. A more realistic projection of 12 flights per year for the 15-year service life combined with the initial development costs would have resulted in a total cost projection for the program of roughly $54 billion (in 2011 dollars).
The total cost of the actual 30-year service life of the Shuttle program through 2011, adjusted for inflation, was $196 billion. In 2010, the incremental cost per flight of the Space Shuttle was $409 million, or to low Earth orbit (LEO). In contrast, the comparable Proton launch vehicle cost was $141 million, or to LEO and the Soyuz 2.1 was $55 million, or , despite these launch vehicles not being reusable.
NASA's budget for 2005 allocated 30%, or $5 billion, to space shuttle operations; this was decreased in 2006 to a request of $4.3 billion. Non-launch costs account for a significant part of the program budget: for example, during fiscal years 2004 to 2006, NASA spent around $13 billion on the Space Shuttle program, even though the fleet was grounded in the aftermath of the Columbia disaster and there were a total of three launches during this period of time. In fiscal year 2009, NASA budget allocated $2.98 billion for 5 launches to the program, including $490 million for "program integration", $1.03 billion for "flight and ground operations", and $1.46 billion for "flight hardware" (which includes maintenance of orbiters, engines, and the external tank between flights.)
Per-launch costs can be measured by dividing the total cost over the life of the program (including buildings, facilities, training, salaries, etc.) by the number of launches. With 135 missions, and the total cost of US$192 billion (in 2010 dollars), this gives approximately $1.5 billion per launch over the life of the Shuttle program. A 2017 study found that carrying one kilogram of cargo to the ISS on the Shuttle cost $272,000 in 2017 dollars, twice the cost of Cygnus and three times that of Dragon.
NASA used a management philosophy known as success-oriented management during the Space Shuttle program which was described by historian Alex Roland in the aftermath of the Columbia disaster as "hoping for the best". Success-oriented management has since been studied by several analysts in the area.
Accidents
In the course of 135 missions flown, two orbiters were destroyed, with loss of crew totalling 14 astronauts:
Challenger – lost 73 seconds after liftoff, STS-51-L, January 28, 1986
Columbia – lost approximately 16 minutes before its expected landing, STS-107, February 1, 2003
There was also one abort-to-orbit and some fatal accidents on the ground during launch preparations.
STS-51-L (Challenger, 1986)
Close-up video footage of Challenger during its final launch on January 28, 1986, clearly shows that the problems began due to an O-ring failure on the right solid rocket booster (SRB). The hot plume of gas leaking from the failed joint caused the collapse of the external tank, which then resulted in the orbiter's disintegration due to high aerodynamic stress. The accident resulted in the loss of all seven astronauts on board. Endeavour (OV-105) was built to replace Challenger (using structural spare parts originally intended for the other orbiters) and delivered in May 1991; it was first launched a year later.
After the loss of Challenger, NASA grounded the Space Shuttle program for over two years, making numerous safety changes recommended by the Rogers Commission Report, which included a redesign of the SRB joint that failed in the Challenger accident. Other safety changes included a new escape system for use when the orbiter was in controlled flight, improved landing gear tires and brakes, and the reintroduction of pressure suits for Shuttle astronauts (these had been discontinued after STS-4; astronauts wore only coveralls and oxygen helmets from that point on until the Challenger accident). The Shuttle program continued in September 1988 with the launch of Discovery on STS-26.
The accidents did not just affect the technical design of the orbiter, but also NASA.
Quoting some recommendations made by the post-Challenger Rogers commission:
STS-107 (Columbia, 2003)
The Shuttle program operated accident-free for seventeen years and 88 missions after the Challenger disaster, until Columbia broke up on reentry, killing all seven crew members, on February 1, 2003. The ultimate cause of the accident was a piece of foam separating from the external tank moments after liftoff and striking the leading edge of the orbiter's left wing, puncturing one of the reinforced carbon-carbon (RCC) panels that covered the wing edge and protected it during reentry. As Columbia reentered the atmosphere at the end of an otherwise normal mission, hot gas penetrated the wing and destroyed it from the inside out, causing the orbiter to lose control and disintegrate.
After the Columbia disaster, the International Space Station operated on a skeleton crew of two for more than two years and was serviced primarily by Russian spacecraft. While the "Return to Flight" mission STS-114 in 2005 was successful, a similar piece of foam from a different portion of the tank was shed. Although the debris did not strike Discovery, the program was grounded once again for this reason.
The second "Return to Flight" mission, STS-121 launched on July 4, 2006, at 14:37 (EDT). Two previous launches were scrubbed because of lingering thunderstorms and high winds around the launch pad, and the launch took place despite objections from its chief engineer and safety head. A five-inch (13 cm) crack in the foam insulation of the external tank gave cause for concern; however, the Mission Management Team gave the go for launch. This mission increased the ISS crew to three. Discovery touched down successfully on July 17, 2006, at 09:14 (EDT) on Runway 15 at Kennedy Space Center.
Following the success of STS-121, all subsequent missions were completed without major foam problems, and the construction of the ISS was completed (during the STS-118 mission in August 2007, the orbiter was again struck by a foam fragment on liftoff, but this damage was minimal compared to the damage sustained by Columbia).
The Columbia Accident Investigation Board, in its report, noted the reduced risk to the crew when a Shuttle flew to the International Space Station (ISS), as the station could be used as a safe haven for the crew awaiting rescue in the event that damage to the orbiter on ascent made it unsafe for reentry. The board recommended that for the remaining flights, the Shuttle always orbit with the station. Prior to STS-114, NASA Administrator Sean O'Keefe declared that all future flights of the Space Shuttle would go to the ISS, precluding the possibility of executing the final Hubble Space Telescope servicing mission which had been scheduled before the Columbia accident, despite the fact that millions of dollars worth of upgrade equipment for Hubble were ready and waiting in NASA warehouses. Many dissenters, including astronauts , asked NASA management to reconsider allowing the mission, but initially the director stood firm. On October 31, 2006, NASA announced approval of the launch of Atlantis for the fifth and final shuttle servicing mission to the Hubble Space Telescope, scheduled for August 28, 2008. However SM4/STS-125 eventually launched in May 2009.
One impact of Columbia was that future crewed launch vehicles, namely the Ares I, had a special emphasis on crew safety compared to other considerations.
Retirement
Preservation
Out of the five fully functional shuttle orbiters built, three remain. Enterprise, which was used for atmospheric test flights but not for orbital flight, had many parts taken out for use on the other orbiters. It was later visually restored and was on display at the National Air and Space Museum's Steven F. Udvar-Hazy Center until April 19, 2012. Enterprise was moved to New York City in April 2012 to be displayed at the Intrepid Museum, whose Space Shuttle Pavilion opened on July 19, 2012. Discovery replaced Enterprise at the National Air and Space Museum's Steven F. Udvar-Hazy Center. Atlantis formed part of the Space Shuttle Exhibit at the Kennedy Space Center visitor complex and has been on display there since June 29, 2013, following its refurbishment.
On October 14, 2012, Endeavour completed an unprecedented drive on city streets from Los Angeles International Airport to the California Science Center, where it has been on display in a temporary hangar since late 2012. The transport from the airport took two days and required major street closures, the removal of over 400 city trees, and extensive work to raise power lines, level the street, and temporarily remove street signs, lamp posts, and other obstacles. Hundreds of volunteers, and fire and police personnel, helped with the transport. Large crowds of spectators waited on the streets to see the shuttle as it passed through the city. Endeavour, along with the last flight-qualified external tank (ET-94), is currently on display at the Science Center's Samuel Oschin Pavilion (in a horizontal orientation) until the completion of the Samuel Oschin Air and Space Center (a planned addition to the California Science Center). Once moved, it will be permanently displayed in launch configuration, complete with genuine solid rocket boosters and external tank.
Crew modules
One area of Space Shuttle applications is an expanded crew. Crews of up to eight have been flown in the Orbiter, but it could have held at least a crew of ten. Various proposals for filling the payload bay with additional passengers were also made as early as 1979. One proposal by Rockwell provided seating for 74 passengers in the Orbiter payload bay, with support for three days in Earth orbit. With a smaller 64 seat orbiter, costs for the late 1980s would be around US$1.5 million per seat per launch. The Rockwell passenger module had two decks, four seats across on top and two on the bottom, including a 25-inch (63.5 cm) wide aisle and extra storage space.
Another design was Space Habitation Design Associates 1983 proposal for 72 passengers in the Space Shuttle Payload bay. Passengers were located in 6 sections, each with windows and its own loading ramp at launch, and with seats in different configurations for launch and landing. Another proposal was based on the Spacelab habitation modules, which provided 32 seats in the payload bay in addition to those in the cockpit area.
There were some efforts to analyze commercial operation of STS. Using the NASA figure for average cost to launch a Space Shuttle as of 2011 at about $450 million per mission, a cost per seat for a 74 seat module envisioned by Rockwell came to less than $6 million, not including the regular crew. Some passenger modules used hardware similar to existing equipment, such as the tunnel, which was also needed for Spacehab and Spacelab
Successors
During the three decades of operation, various follow-on and replacements for the STS Space Shuttle were partially developed but not finished.
Examples of possible future space vehicles to supplement or supplant STS:
Advanced Crewed Earth-to-Orbit Vehicle
Shuttle II, Johnson Space Center concept for a follow-on, with 2 boosters and 2 tanks mounted on its wings.
National Aero-Space Plane (NASP)
Rockwell X-30 (not funded)
VentureStar, SSTO spacelane concept using an aerospike engine.
Lockheed Martin X-33 (cancelled 2001)
Ares I (ended with Constellation cancellation)
Orbital Space Plane Program
One effort in the direction of space transportation was the Reusable Launch Vehicle (RLV) program, initiated in 1994 by NASA. This led to work on the X-33 and X-34 vehicles. NASA spent about US$1 billion on developing the X-33 hoping for it be in operation by 2005. Another program around the turn of the millennium was the Space Launch Initiative, which was a next generation launch initiative.
The Space Launch Initiative program was started in 2001, and in late 2002 it was evolved into two programs, the Orbital Space Plane Program and the Next Generation Launch Technology program. OSP was oriented towards provided access to the International Space Station.
Other vehicles that would have taken over some of the Shuttles responsibilities were the HL-20 Personnel Launch System or the NASA X-38 of the Crew Return Vehicle program, which were primarily for getting people down from ISS. The X-38 was cancelled in 2002, and the HL-20 was cancelled in 1993. Several other programs in this existed such as the Station Crew Return Alternative Module (SCRAM) and Assured Crew Return Vehicle (ACRV)
According to the 2004 Vision for Space Exploration, the next human NASA program was to be Constellation program with its Ares I and Ares V launch vehicles and the Orion spacecraft; however, the Constellation program was never fully funded, and in early 2010 the Obama administration asked Congress to instead endorse a plan with heavy reliance on the private sector for delivering cargo and crew to LEO.
The Commercial Orbital Transportation Services (COTS) program began in 2006 with the purpose of creating commercially operated uncrewed cargo vehicles to service the ISS. The first of these vehicles, SpaceX Dragon 1, became operational in 2012, and the second, Orbital Sciences's Cygnus did so in 2014.
The Commercial Crew Development (CCDev) program was initiated in 2010 with the purpose of creating commercially operated crewed spacecraft capable of delivering at least four crew members to the ISS, staying docked for 180 days and then returning them back to Earth. These spacecraft, like SpaceX's Dragon 2 and Boeing CST-100 Starliner were expected to become operational around 2020. On the Crew Dragon Demo-2 mission, SpaceX's Dragon 2 sent astronauts to the ISS, restoring America's human launch capability. The first operational SpaceX mission launched on November 15, 2020, at 7:27:17 p.m. ET, carrying four astronauts to the ISS.
Although the Constellation program was canceled, it has been replaced with a very similar Artemis program. The Orion spacecraft has been left virtually unchanged from its previous design. The planned Ares V rocket has been replaced with the smaller Space Launch System (SLS), which is planned to launch both Orion and other necessary hardware. Exploration Flight Test-1 (EFT-1), an uncrewed test flight of the Orion spacecraft, launched on December 5, 2014, on a Delta IV Heavy rocket.
Artemis 1 is the first flight of the SLS and was launched as a test of the completed Orion and SLS system. During the mission, an uncrewed Orion capsule spent 10 days in a distant retrograde orbit around the Moon before returning to Earth. Artemis 2, the first crewed mission of the program, will launch four astronauts in 2024 on a free-return flyby of the Moon at a distance of . After Artemis 2, the Power and Propulsion Element of the Lunar Gateway and three components of an expendable lunar lander are planned to be delivered on multiple launches from commercial launch service providers. Artemis 3 is planned to launch in 2025 aboard a SLS Block 1 rocket and will use the minimalist Gateway and expendable lander to achieve the first crewed lunar landing of the program. The flight is planned to touch down on the lunar south pole region, with two astronauts staying there for about one week.
Gallery
Assets and transition plan
The Space Shuttle program occupied over 654 facilities, used over 1.2 million line items of equipment, and employed over 5,000 people. The total value of equipment was over $12 billion. Shuttle-related facilities represented over a quarter of NASA's inventory. There were over 1,200 active suppliers to the program throughout the United States. NASA's transition plan had the program operating through 2010 with a transition and retirement phase lasting through 2015. During this time, the Ares I and Orion as well as the Altair Lunar Lander were to be under development, although these programs have since been canceled.
In the 2010s, two major programs for human spaceflight are Commercial Crew Program and the Artemis program. Kennedy Space Center Launch Complex 39A is, for example, used to launch Falcon Heavy and Falcon 9.
Criticism
Support vehicles
Many other vehicles were used in support of the Space Shuttle program, mainly terrestrial transportation vehicles.
The crawler-transporter carried the mobile launcher platform and the Space Shuttle from the Vehicle Assembly Building (VAB) to Launch Complex 39, originally built for Project Apollo.
The Shuttle Carrier Aircraft (SCA) were two modified Boeing 747s. Either could fly an orbiter from alternative landing sites back to the Kennedy Space Center. These aircraft were retired to the Joe Davies Heritage Airpark at the Armstrong Flight Research Center and Space Center Houston.
A 36-wheeled transport trailer, the Orbiter Transfer System, originally built for the U.S. Air Force's launch facility at Vandenberg Air Force Base in California (since then converted for Delta IV rockets) would transport the orbiter from the landing facility to the launch pad, which allowed both "stacking" and launch without utilizing a separate VAB-style building and crawler-transporter roadway. Prior to the closing of the Vandenberg facility, orbiters were transported from the OPF to the VAB on their undercarriages, only to be raised when the orbiter was being lifted for attachment to the SRB/ET stack. The trailer allowed the transportation of the orbiter from the OPF to either the SCA "Mate-Demate" stand or the VAB without placing any additional stress on the undercarriage.
The Crew Transport Vehicle (CTV), a modified airport jet bridge, was used to assist astronauts to egress from the orbiter after landing. Upon entering the CTV, astronauts could take off their launch and reentry suits then proceed to chairs and beds for medical checks before being transported back to the crew quarters in the Operations and Checkout Building. Originally built for Project Apollo.
The Astrovan was used to transport astronauts from the crew quarters in the Operations and Checkout Building to the launch pad on launch day. It was also used to transport astronauts back again from the Crew Transport Vehicle at the Shuttle Landing Facility.
The three locomotives serving the NASA Railroad, used to transport segments of the Space Shuttle Solid Rocket Boosters, were determined to be no longer needed for day-to-day operation at the Kennedy Space Center. In April 2015, locomotive No. 1 was sent to Natchitoches Parish Port and No. 3 sent to the Madison Railroad. Locomotive No. 2 was sent to the Gold Coast Railroad Museum in 2014.
See also
List of human spaceflights
List of Space Shuttle missions
List of spaceflight-related accidents and incidents
List of Space Shuttle crews
Simulation
Physics
Other spaceflight programs
Similar vehicles
Dream Chaser – Commercial space glider for flying either cargo or a crew to the ISS
ReferencesFootnotesCitations'''
Further reading
Shuttle Reference manual
Orbiter Vehicles
Shuttle Program Funding 1992 – 2002
NASA Space Shuttle News Reference – 1981 (PDF document)
R. A. Pielke, "Space Shuttle Value open to Interpretation", Aviation Week'', issue 26. July 1993, p. 57 (.pdf)
External links
Official NASA Mission Site
NASA Johnson Space Center Space Shuttle Site
Official Space Shuttle Mission Archives
NASA Space Shuttle Multimedia Gallery & Archives
Shuttle audio, video, and images – searchable archives from STS-67 (1995) to present
Kennedy Space Center Media Gallery – searchable video/audio/photo gallery
Congressional Research Service (CRS) Reports regarding the Space Shuttle
U.S. Space Flight History: Space Shuttle Program
Weather criteria for Shuttle launch
Consolidated Launch Manifest: Space Shuttle Flights and ISS Assembly Sequence
USENET posting – Unofficial Space FAQ by Jon Leech
NASA programs
Human spaceflight programs
1972 establishments in the United States
2011 disestablishments in the United States
Articles containing video clips | Space Shuttle program | Engineering | 5,756 |
28,105,432 | https://en.wikipedia.org/wiki/R136a1 | R136a1 (short for RMC 136a1) is one of the most massive and luminous stars known, at nearly and nearly 4.7 million , and is also one of the hottest, at around . It is a Wolf–Rayet star at the center of R136, the central concentration of stars of the large NGC 2070 open cluster in the Tarantula Nebula (30 Doradus) in the Large Magellanic Cloud. The cluster can be seen in the far southern celestial hemisphere with binoculars or a small telescope, at magnitude 7.25. R136a1 itself is 100 times fainter than the cluster and can only be resolved using speckle interferometry.
Discovery
In 1960, a group of astronomers working at the Radcliffe Observatory in Pretoria made systematic measurements of the brightness and spectra of bright stars in the Large Magellanic Cloud (LMC). Among the objects cataloged was RMC 136 (Radcliffe observatory Magellanic Cloud catalog number 136), the central "star" of the Tarantula Nebula, which the observers concluded was probably a multiple star system. Subsequent observations showed that R136 was located in the middle of a giant region of ionized interstellar hydrogen, known as an H II region, which was a center of intense star formation in the immediate vicinity of the observed stars.
In 1979, ESO's 3.6 m telescope was used to resolve R136 into three components; R136a, R136b, and R136c. The exact nature of R136a was unclear and a subject of intense discussion. Estimates that the brightness of the central region would require as many as 100 hot O class stars within half a parsec at the centre of the cluster led to speculation that a star 3,000 times the mass of the Sun was the more likely explanation.
The first demonstration that R136a was a star cluster was provided by Weigelt and Beier in 1985. Using the speckle interferometry technique, R136a was shown to be made up of 8 stars within 1 arcsecond at the centre of the cluster, with R136a1 being the brightest.
Final confirmation of the nature of R136a came after the launch of the Hubble Space Telescope. Its Wide Field and Planetary Camera (WFPC) resolved R136a into at least 12 components and showed that R136 contained over 200 highly luminous stars. The more advanced WFPC2 allowed the study of 46 massive luminous stars within half a parsec of R136a and over 3,000 stars within a 4.7 parsec radius.
Visibility
In the night sky, R136 appears as a 10th magnitude object at the core of the NGC 2070 cluster embedded in the Tarantula Nebula in the Large Magellanic Cloud. It required a 3.6 metre telescope to detect R136a as a component of R136 in 1979, and resolving R136a to detect R136a1 requires a space telescope or sophisticated techniques such as adaptive optics or speckle interferometry.
South of about the 20th parallel south, the LMC is circumpolar, meaning that it can be seen (at least in part) all night every night of the year, weather and light pollution permitting. In the Northern Hemisphere, it can be visible south of the 20th parallel north. This excludes North America (except southern Mexico), Europe, northern Africa and northern Asia.
Surroundings
The R136a system at the core of R136 is a dense luminous knot of stars containing at least 12 stars, the most prominent being R136a1, R136a2, and R136a3, all of which are extremely luminous and massive WN5h stars. R136a1 is separated from R136a2, the second brightest star in the cluster, by 5,000 AU.
R136 is located approximately 157,000 light-years from Earth in the Large Magellanic Cloud, positioned on the south-east corner of the galaxy at the centre of the Tarantula Nebula, also known as 30 Doradus. R136 itself is just the central condensation of the much larger NGC 2070 open cluster.
For such a distant star, R136a1 is relatively unobscured by interstellar dust. The reddening causes the visual brightness to be reduced by about 1.8 magnitudes, but only around 0.22 magnitudes in the near infrared.
Distance
The distance to R136a1 cannot be determined directly, but is assumed to be at the same distance as the Large Magellanic Cloud at around 50 kiloparsecs or 163,000 light years.
Properties
Binary
A possible binary companion to R136a1 has been resolved, although there is a 25% possibility that it is a chance alignment.
X-ray emission was detected from R136 using the Chandra X-ray Observatory. R136a and R136c were both clearly detected, but R136a could not be resolved. Another study separated the R136a1/2 pair from R136a3. R136a1/2 showed relatively soft x-rays not thought to indicate a colliding winds binary.
Rapid Doppler radial velocity variations would be expected from a pair of equal mass stars in a close orbit, but this has not been seen in the R136a1 spectrum. A high orbital inclination, a more distant binary, or a chance alignment of two distant stars cannot be completely ruled out but is thought to be unlikely. Highly unequal binary components are possible, but would not affect the modelling of R136a1's properties.
Classification
R136a1 is a high-luminosity WN5h star, placing it on the extreme top left corner of the Hertzsprung–Russell diagram. A Wolf–Rayet star is distinguished by the strong, broad emission lines in its spectrum. This includes ionized nitrogen, helium, carbon, oxygen and occasionally silicon, but with hydrogen lines usually weak or absent. A WN5 star is classified on the basis of ionised helium emission being considerably stronger than the neutral helium lines, and having roughly equal emission strength from NIII, NIV, and NV. The "h" in the spectral type indicates significant hydrogen emission in the spectrum, and hydrogen is calculated to make up 40% of the surface abundance by mass.
WNh stars as a class are massive luminous stars still burning hydrogen at their cores. The emission spectrum is produced in a powerful dense stellar wind, and the enhanced levels of helium and nitrogen arise from convectional mixing of CNO cycle products to the surface.
Mass
Current estimates, as of 2024, place the mass of R136a1 at around . Higher, less rigid estimates exist, such as an evolutionary mass of found from HST visual spectra using a non-LTE line-blanketed CMFGEN model atmosphere. R136a1 closely matches the expected properties for an initially rapidly rotating star with LMC metallicity after shining for about a million years.
An earlier analysis using ultraviolet spectroscopy found a current mass of and an initial mass of .
A current mass of is found in similar analysis using PoWR (Potsdam Wolf–Rayet) atmospheric models with optical and ultraviolet spectra and a mass–luminosity relation, assuming a single star.
R136a1 is undergoing extreme mass loss through a stellar wind reaching a velocity of . This is caused by intense electromagnetic radiation from the very hot photosphere accelerating material away from the surface more strongly than gravity can retain it. Mass loss is largest for high-luminosity stars with low surface gravity and enhanced levels of heavy elements in the photosphere. R136a1 loses () per year, over a billion times more than the Sun loses, and is expected to have shed about since its formation.
Luminosity
At around , R136a1 is one of the most luminous stars known, radiating more energy in four seconds than the Sun does in a year. From 2010 to 2020 it was recognized as the most massive and luminous star known. If it replaced the Sun in the Solar System, it would outshine the Sun by 164,000 times (MV = −8.2) and would appear from Earth at magnitude −40. Its brightness at a distance of 10 parsecs, the absolute visual magnitude, would be −8.18, three magnitudes brighter than Venus ever appears from Earth. Its brightness at the distance of the nearest star to Earth, Proxima Centauri (just over a parsec), would be about the same as the full moon.
R136a1 supplies c. 7% of the ionizing flux of the entire 30 Doradus region, as much as 70 O7 main-sequence stars. Along with R136a2, a3, and c, it produces 43–46% of the Lyman continuum radiation of the whole R136 cluster.
Massive stars lie close to the Eddington limit, the luminosity at which the radiation pressure acting outwards at the surface of the star equals the force of the star's gravity pulling it inward. Above the Eddington limit, a star generates so much energy that its outer layers are rapidly thrown off. This effectively restricts stars from shining at higher luminosities for long periods. The classical Eddington luminosity limit is not applicable to stars such as R136a1 that are not in hydrostatic equilibrium, and its calculation is extremely complex for real stars. The empirical Humphrey-Davidson limit has been identified as a luminosity limit for observed stars, but recent models have attempted to calculate useful theoretical Eddington limits applicable to massive stars. R136a1 is currently around 70% of its Eddington luminosity.
Temperature
R136a1 has a surface temperature of around , eight times as hot as the Sun, and with peak radiation in the extreme ultraviolet.
R136a1 has a B–V index of about 0.03, which is a typical colour for an F-type star. The "U–V" colour from the HST WFPC2 and filters is −1.28, more indicative of an extremely hot star. This variation of different colour indices relative to a blackbody is the result of interstellar dust causing reddening and extinction. The reddening (EB–V) can be used to estimate the level of visual extinction (AV). EB–V values of 0.29–0.37 have been measured, with considerable uncertainty due to contamination from close neighbours such as R136a2 0.1" away, leading to AV around 1.80 and a de-reddened B–V (B–V0) of −0.30.
The effective temperature of a star can be approximated from the colour, but this is not very accurate and spectral fitting to an atmospheric model is necessary to derive the temperature. Temperatures of 53,000–56,000 K are found for R136a1 using different atmospheric models. Older models had produced temperatures around and hence dramatically lower luminosities. The extreme temperature of the star causes its peak radiation to be around and nearly 99% of the radiation to be emitted outside the visual range (a bolometric correction around −5).
Size
R136a1 is over forty times the radius of the Sun () which corresponds to a volume nearly 80,000 times larger than the Sun.
R136a1 does not have a well-defined visible surface like the Earth or the Sun. The hydrostatic main body of the star is surrounded by a dense atmosphere being accelerated outwards into the stellar wind. An arbitrary point within this wind is defined as the surface for measuring the radius, and different authors may use different definitions. For example, a Rosseland optical depth of 2/3 corresponds approximately to a visible surface while a Rosseland depth of 20 or 100 corresponds more closely to a physical photosphere. Stellar temperatures are typically quoted at the same depth so that the radius and temperature correspond to the luminosity.
R136a1's dimensions are far smaller than the largest stars: red supergiants are , tens of times larger than R136a1. Despite the large mass and modest dimensions, R136a1 has an average density less than 1% of the Sun's. At about 5 kg/m3, it is around 4 times denser than Earth's atmosphere at sea level; alternatively, less than a hundredth the density of water.
Rotation
The rotation rate of R136a1 cannot be measured directly since the photosphere is hidden by the dense stellar wind and the photospheric absorption lines used to measure rotational doppler broadening are not present in the spectrum. A NV emission line at 2.1 μm is produced relatively deep in the wind and can be used to estimate rotation. In R136a1 it has a FWHM of about 15 Å, indicating a slow or non rotating star, although it could be aligned with its pole facing Earth. R136a2 and a3 are rotating rapidly and the closest evolutionary models for R136a1 match a star still rotating with an equatorial speed of c. 200 km/s after c. 1.75 Myr.
Evolution
Current state
R136a1 is currently fusing hydrogen to helium, predominantly by the CNO cycle due to the high temperatures at the core. Despite the Wolf–Rayet spectral appearance, it is a young star, just over a million years old. The emission spectrum is created by a dense stellar wind caused by the extreme luminosity, with the enhanced levels of helium and nitrogen being mixed from the core to the surface by strong convection. It is effectively a WR-type main sequence star. Over 90% of the star is convective, with a small non-convective layer at the surface.
Development
Models of star formation by accretion from molecular clouds predict an upper limit to the mass a star can achieve before its radiation prevents further accretion. The most simplistic accretion models at population I metallicities predict a limit as low as , but more complex theories allow masses several times higher. An empirical limit of around has become widely accepted. R136a1 clearly exceeds all these limits, leading to development of new single star accretion models potentially removing the upper limit, and the potential for massive star formation by stellar mergers.
As a single star formed from accretion, the properties of such a massive star are still uncertain. Synthetic spectra indicate that it would never have a main sequence luminosity class (V), or even a normal O type spectrum. The high luminosity, proximity to the Eddington limit, and strong stellar wind, would be likely to create an If* or WNh spectrum as soon as R136a1 became visible as a star. Helium and nitrogen are rapidly mixed to the surface due to the large convective core and high mass loss, and their presence in the stellar wind creates the characteristic Wolf–Rayet emission spectrum. The ZAMS at very high masses curves back to cooler temperatures, and at LMC metallicities the maximum temperature predicted to be around 56,000 K for stars, so R136a1 would have been slightly cooler than some less massive main sequence stars.
During core hydrogen burning, the helium fraction in the core increases and according to the virial theorem the core pressure and temperature will increase. This leads to an increase in luminosity so that R136a1 is somewhat more luminous now than when it first formed. The temperature decreases slightly, but the outer layers of the star have inflated, driving even higher mass loss.
Future
The future development of R136a1 is uncertain, and there are no comparable stars to confirm predictions. The evolution of massive stars depends critically on the amount of mass they can lose, and various models give different results, none of which entirely match observations. It is thought that WNh stars develop into LBVs as hydrogen at the core starts to become depleted. This is an important phase of extreme mass loss which enables a star, at near solar metallicity, to transition to a hydrogen-free Wolf–Rayet star. Stars with sufficiently strong mixing from the core to the surface, due to the very large convective core, high metallicity, or additional rotational mixing, may skip the LBV phase and evolve directly from the hydrogen-rich WNh phase to the hydrogen-poor WN phase. Hydrogen fusion lasts for a little over two million years, and the star's mass at the end is expected to be . A single star with LMC metallicity, even if it starts out rotating very rapidly, will be braked to near zero rotation by the end of hydrogen burning.
After core helium fusion starts, the remaining hydrogen in the atmosphere is rapidly lost and R136a1 will quickly contract to a hydrogen-free WNE star and the luminosity will decrease. Wolf–Rayet stars at this point are mostly helium and they lie on the Zero Age Helium Main Sequence (He-ZAMS), analogous to and parallel to the hydrogen-burning main sequence but at hotter temperatures.
During helium burning, carbon and oxygen will accumulate in the core and heavy mass loss continues. This eventually leads to the development of a WC spectrum, although at LMC metallicity a star is expected to spend most of the helium burning phase with a WN spectrum. Towards the end of helium burning, core temperature increase and mass loss cause an increase in both luminosity and temperature, with the spectral type becoming WO. Several hundred thousand years will be spent fusing helium, but the final stages of heavier element burning take no more than a few thousand years. R136a1 will eventually shrink to a little over , with just of helium left surrounding the core.
Supernova
Any star which produces a carbon–oxygen (C–O) core more massive than the maximum for a white dwarf (c. ) will inevitably suffer core collapse. This usually happens when an iron core has been produced and fusion can no longer produce the energy required to prevent core collapse, although it can happen in other circumstances.
A C–O core between about and will become so hot that the gamma radiation will spontaneously produce electron–positron pairs and the sudden loss of energy in the core will cause it to collapse as a pair-instability supernova (PISN), sometimes called a pair-creation supernova (PCSN). A PISN is usually only produced in very low metallicity stars that do not lose sufficient mass to keep their C–O core sizes below . This can also occur at LMC metallicity for very massive stars, but the predicted C–O core size for R136a1 is below so a PISN is unlikely.
Iron core collapse may produce a supernova explosion, and sometimes a gamma-ray burst (GRB). The type of any supernova explosion will be a type I since the star has no hydrogen; type Ic since it has almost no helium. Particularly massive iron cores may collapse the entire star into a black hole with no visible explosion, or a sub-luminous supernova as radioactive 56Ni falls back onto the black hole.
A type Ic supernova can produce a GRB if the star is rotating and has an appropriate mass. R136a1 is expected to lose almost all its spin long before core collapse so a GRB is unlikely.
The remnant from a type Ic core collapse supernova is either a neutron star or black hole, depending on the mass of the progenitor core. For a star as massive as R136a1, the remnant will very likely be a black hole instead of a neutron star.
See also
Hypergiant
List of most luminous stars
List of most massive stars
VY Canis Majoris — one of the largest stars and red supergiants
BAT99-98 — one of the most massive stars
R136a2
References
Stars in the Large Magellanic Cloud
Tarantula Nebula
Extragalactic stars
Wolf–Rayet stars
Dorado
?
Large Magellanic Cloud | R136a1 | Astronomy | 4,125 |
14,133,729 | https://en.wikipedia.org/wiki/GATA4 | Transcription factor GATA-4 is a protein that in humans is encoded by the GATA4 gene.
Function
This gene encodes a member of the GATA family of zinc finger transcription factors. Members of this family recognize the GATA motif which is present in the promoters of many genes. This protein is thought to regulate genes involved in embryogenesis and in myocardial differentiation and function. Mutations in this gene have been associated with cardiac septal defects as well as reproductive defects.
GATA4 is a critical transcription factor for proper mammalian cardiac development and essential for survival of the embryo. GATA4 works in combination with other essential cardiac transcription factors as well, such as Nkx2-5 and Tbx5. GATA4 is expressed in both embryo and adult cardiomyocytes where it functions as a transcriptional regulator for many cardiac genes, and also regulates hypertrophic growth of the heart. GATA4 promotes cardiac morphogenesis, cardiomyocytes survival, and maintains cardiac function in the adult heart.
Mutations or defects in the GATA4 gene can lead to a variety of cardiac problems including congenital heart disease, abnormal ventral folding, and defects in the cardiac septum separating the atria and ventricles, and hypoplasia of the ventricular myocardium. As seen from the abnormalities from deletion of GATA4, it is essential for cardiac formation and the survival of the embryo during fetal development.
GATA4 is not only important for cardiac development, but also development and function of the mammalian fetal ovary and contributes to fetal male gonadal development and mutations may lead to defects in reproductive development. GATA4 has also been discovered to have an integral role in controlling the early stages of pancreatic and hepatic development.
GATA4 is regulated through the autophagy-lysosome pathway in eukaryotic cells. In cellular senescence, ATM and ATR inhibit p62, an autophagy adaptor responsible for selective autophagy of GATA4. Inhibition of p62 leads to increased GATA4 levels, resulting in NF-kB activation and subsequent SASP induction.
Atrioventricular valve formation
GATA4 expression during cardiac development has been shown to be essential to proper atrioventricular (AV) formation and function. Endocardial cells undergo epithelial to mesenchymal transitions (EMT) into the AV cushions during development. Their proliferation and fusion leads to division of the ventricular inlet into two different passageways with two AV valves, and they are thought to be under the influence of the GATA4 transcription factor. GATA4 inactivation, with GATA4-null mice, leads to down regulation of Erbb3 and altered Erk expression, two other important molecules in EMT and ventricular inlet separation. This has been shown to lead to pericardial effusion and peripheral hemorrhage in E12.5 mice, which succumb due to heart failure before weaning age. This data could have important implications for human medicine by suggesting that mutations with the GATA4 transcription factor could be responsible for AV cushion defects in humans with improper septal formation leading to congenital heart disease.
Interactions
GATA4 has been shown to interact with NKX2-5, TBX5, Serum response factor HAND2, and HDAC2.
GATA4 has also been shown to interact with Erbb3, FOG-1, and FOG-2.
Clinical relevance
Mutations in this gene have been associated to cases of congenital diaphragmatic hernia. Atrial septal defects, tetralogy of Fallot, and ventricular septal defects associated with GATA4 mutation were also seen in South Indian patients.
See also
GATA transcription factor
References
Further reading
External links
Transcription factors | GATA4 | Chemistry,Biology | 788 |
77,958,629 | https://en.wikipedia.org/wiki/NGC%206605 | NGC 6605 is an open cluster located in the constellation Serpens. It was discovered by the British astronomer John Herschel in 1826.
Description
With a visual magnitude of 6.0, this cluster is visible to the naked eye from a very dark location free of light pollution. Elsewhere, however, the cluster can be observed with small binoculars.
NGC 6605 is located approximately 3.1 degrees southwest of Gamma Scuti, a magnitude 4.67 star in the constellation Scutum.
The apparent size of the cluster is 29 arc minutes, which, given the distance of 1144 pc and through simple calculation, equates to an actual size of about 31 light years.
See also
Pleiades
References
Open clusters
6605
Serpens | NGC 6605 | Astronomy | 151 |
42,068,958 | https://en.wikipedia.org/wiki/Drinfeld%E2%80%93Sokolov%E2%80%93Wilson%20equation | The Drinfeld–Sokolov–Wilson (DSW) equations are an integrable system of two coupled nonlinear partial differential equations proposed by Vladimir Drinfeld and Vladimir Sokolov, and independently by George Wilson:
References
Nonlinear partial differential equations
Integrable systems | Drinfeld–Sokolov–Wilson equation | Physics | 57 |
33,702,893 | https://en.wikipedia.org/wiki/Surface%20rheology | Surface rheology is a description of the rheological properties of a free surface. When perfectly pure, the interface between fluids usually displays only surface tension. The stress within a fluid interface can be affected by the adsorption of surfactants in several ways:
Change in the surface concentration of surfactants when the in-plane flow tends to alter the surface area of the interface (Gibbs' elasticity).
Adsorption/desorption of the surfactants to/from the interface.
Importance of surface rheology
The mechanical properties (rheology) of dispersed media such as liquid foams and emulsions is strongly affected by surface rheology. Indeed, when they consist of two (or more) fluid phases, deforming the material implies deforming the constitutive phases (bubbles, drops) and thus their interfaces.
The measurement of surface rheological properties is described by storage and loss moduli. In the case of a linear response to a sinusoidal deformation, the loss modulus is the product of the viscosity by the frequency. One of the difficulties of surface rheology measurements come from the fact that the adsorbed layers are usually rather compressible (at the difference of bulk fluids which are essentially incompressible), and both compression and shear parameters should be determined. This determination requires different type of rheometric instruments, for instance oscillating drops for the compression properties and oscillating bicones for the shear properties. These two methods allow investigating the variation of the parameters upon the amplitude of the deformation. The responses of adsorbed layers to deformations are frequently non-linear, making this variation measurement relevant to rheological studies.
References
Rheology | Surface rheology | Chemistry | 361 |
32,753,683 | https://en.wikipedia.org/wiki/Formylglycine-generating%20enzyme | Formylglycine-generating enzyme (FGE), located at 3p26.1 in humans, is the name for an enzyme present in the endoplasmic reticulum that catalyzes the conversion of cysteine to formylglycine (fGly). There are two main classes of FGE, aerobic and anaerobic. FGE activates sulfatases, which are essential for the degradation of sulfate esters. The catalytic activity of sulfatases is dependent upon a formylglycine (sometimes called oxoalanine) residue in the active site.
Aerobic
The aerobic enzyme has a structure homologous to the complex alpha/beta topology found in the gene product of human sulfatase-modifying factor 1 (SUMF1). Aerobic FGE converts a cysteine residue in the highly conserved consensus sequence CXPXR to fGly. To do so, FGE "activates" its target by utilizing mononuclear copper. The substrate first binds to copper, increasing reactivity of the substrate-copper complex with oxygen. Activation is then accomplished through oxidation of a cysteine residue in the substrate-copper complex. Due to the nature of this reaction, FGE is termed a "copper-dependent metalloenzyme.
Anaerobic
The most well-studied anaerobic FGE is the bacterial AtsB, an iron-sulfur cluster containing enzyme present in Klebsiella pneumoniae, that is able to convert either cysteine or serine to fGly with a distinctly different mechanism than the aerobic form. While AtsB can convert either, its activity increases four fold when in the presence of cysteine over serine. AtsB is 48% similar to an enzyme present in Clostridium perfringens. Both enzymes possess the Cx3Cx2C motif unique to the radical S-adenosyl methionine superfamily and are able to use a reduction reaction to cleave S-adenosyl methionine. These two enzymes fall into a larger group called the anaerobic Sulfatase Maturing Enzymes, which are able to convert cysteine into fGly without the use of oxygen.
Protein domain
In molecular biology, "formylglycine-generating enzyme" (sometimes annotated as formylglycine-generating sulfatase enzyme) is the name of the FGE protein domain, whether or not the protein is catalytically active. Both prokaryotic and eukaryotic homologs of FGE possess highly conserved active sites — including the catalytic cysteine residues required for enzymatic function. Activation of molecular oxygen is thought to be carried out by conserved residues close to the FGE catalytic site in aerobic organisms. The catalytic cysteine residues are involved in a thiol-cysteine exchange leading to the ultimate production of fGly.
Disease states
In humans, mutations in SUMF1 result in defects in FGE, which in turn causes the impairment of sulfatases. The result is a disease called multiple sulfatase deficiency (MSD), in which the accumulation of glycosaminoglycans or sulfolipids can cause early infant death. This disease can be further differentiated into neonatal, late infantile, and juvenile, with neonatal being the most severe. Common symptoms include ichthyosis, hypotonia, skeletal abnormalities, and overall cognitive decline. In 2017 Weidner et al., found an association with SUMF1 expression and chronic obstructive pulmonary disease (COPD) development. As of January 2020, there were more than 100 reported cases worldwide of MSD. Known substrates for SUMF1 are: N-acetylgalactosamine-6-sulfate sulfatase (GALNS), arylsulfatase A (ARSA), steroid sulfatase (STS) and arylsulfatase L (ARSL); all molecules that contain cysteine. FGE converts this cysteine group into C-𝛼-formylglycine. SUMF1 occurs in the endoplasmic reticulum or its lumen.
References
Protein domains | Formylglycine-generating enzyme | Biology | 867 |
39,066 | https://en.wikipedia.org/wiki/List%20of%20religions%20and%20spiritual%20traditions | While the word religion is difficult to define, one standard model of religion used in religious studies courses defines it as
Many religions have narratives, symbols, traditions and sacred histories that are intended to give meaning to life or to explain the origin of life or the universe. They tend to derive morality, ethics, religious laws, or a preferred lifestyle from their ideas about the cosmos and human nature. According to some estimates, there are roughly 4,200 religions, churches, denominations, religious bodies, faith groups, tribes, cultures, movements, or ultimate concerns.
The word religion is sometimes used interchangeably with the words "faith" or "belief system", but religion differs from private belief in that it has a public aspect. Most religions have organized behaviours, including clerical hierarchies, a definition of what constitutes adherence or membership, congregations of laity, regular meetings or services for the purposes of veneration of a deity or for prayer, holy places (either natural or architectural) or religious texts. Certain religions also have a sacred language often used in liturgical services. The practice of a religion may also include sermons, commemoration of the activities of a God or gods, sacrifices, festivals, feasts, trance, rituals, liturgies, ceremonies, worship, initiations, funerals, marriages, meditation, invocation, mediumship, music, art, dance, public service, or other aspects of human culture. Religious beliefs have also been used to explain parapsychological phenomena such as out-of-body experiences, near-death experiences, and reincarnation, along with many other paranormal and supernatural experiences.
Some academics studying the subject have divided religions into three broad categories: world religions, a term which refers to transcultural, international faiths; Indigenous religions, which refers to smaller, culture-specific or nation-specific religious groups; and new religious movements, which refers to recently developed faiths. One modern academic theory of religion, social constructionism, says that religion is a modern concept that suggests all spiritual practice and worship follows a model similar to the Abrahamic religions as an orientation system that helps to interpret reality and define human beings, and thus believes that religion, as a concept, has been applied inappropriately to non-Western cultures that are not based upon such systems, or in which these systems are a substantially simpler construct.
Eastern religions
Eastern religions are the religions which originated in East, South and Southeast Asia encompassing a diverse range of eastern and spiritual traditions.
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New Calvinism
Presbyterianism
Zwinglianism
Reformed Eastern Christianity
Restoration movement (a.k.a. "Restorationism")
Adventism
Seventh-day Adventist Church
Churches of Christ
Bible Student movement
Jehovah's Witnesses
Latter Day Saint movement
The Church of Jesus Christ of Latter-day Saints
Mormon fundamentalism
Swedenborgianism (a.k.a. "The New Church")
Unitarianism
Roman Catholic Church/Latin Church (a.k.a. "Roman Catholicism" or "Catholicism")
Black Catholicism
Charismatic Catholics
Gallicanism
Independent Catholic churches (a.k.a "Independent Catholicism")
Old Catholic Church
Liberal Catholicism
Modernist Catholics
Traditionalist Catholics
Sedevacantism
Sedeprivationism
Ultramontanism
Syncretic
Cult of El Tío
Cult of María Lionza
Cult of Santa Muerte
Esoteric Christianity
Christian Theosophy
Christopaganism
Martinism
Folk Christianity
Folk Catholicism
Folk Orthodoxy
God Worshipping Society (Historical)
Judaizers (Judeo-Christian)
Christian Kabbalah
Messianic Judaism
Rizalista
Spiritual Baptist
Other
American Civil Religion
Christian Universalism
Nondenominational Christianity
Nontrinitarianism
Islam
Khawarij
Azraqi (Historical)
Haruriyyah (Historical)
Ibadi
Najdat (Historical)
Sufri (Historical)
Shia Islam
Alevism
Alians
Bektashism
Kurdish Alevism
Alawites (Nusayris)
Isma'ilism
Mustaali
Dawoodi Bohra
Alavi Bohra
Atba-i-Malak
Atba-i-Malak Badar
Atba-i-Malak Vakil
Hebtiahs Bohra
Progressive Dawoodi Bohra
Sulaymani
Nizari
Twelver
Ja'fari jurisprudence
Akhbari
Shaykhism
Usuli
Zaidiyyah
Jarudiyah
Batriyya
Sufism
Bektashi Order
Chishti Order
Kubrawiya
Khufiyya
Mevlevi Order
Mouride
Naqshbandi
Jahriyya
Ni'matullāhī
Qadiriyya
Roshani
Shadhili
Suhrawardiyya
Sufi Order International
Tijaniyyah
Universal Sufism
Sunni Islam
Kalam/Fiqh
Ash'ari
Maliki
Shafi'i
Hanbali
Maturidi
Hanafi
Barelvi
Deobandi
Gedimu
Athari
Salafi
Madkhalism
Wahhabism
Ahle Hadith
Islamism
Islamic Modernism
Muʿtazila
Syncretic
Abangan
Ali-Illahism
Din-i Ilahi
Kafirism
Wetu Telu
Satpanth
Barmati Panth
Other
Ahmadiyya
Avicennism
Chinese Islam
European Islam
Illuminationism
Jadid
Liberal movements within Islam
Mahdavia
Mahdist movement
Quranism
Riaz Ahmed Gohar Shahi
Messiah Foundation International
Transcendent Theosophy
Zikrism
Judaism
Historical Judaism
Biblists
Essenes
Bana'im
Hemerobaptists (possible ancestor of Mandaeism)
Maghāriya
Nasoraeans (ancestor of Mandaeism)
Hellenistic Judaism
Houses of Hillel and Shammai
Hypsistarianism
Magarites
Messianic sects
Ebionites
Elcesaites
Nazirite
Okbarites
Pharisees (ancestor of Rabbinic Judaism)
Sabbateans
Frankism
Sadducees (possible ancestor of Karaite Judaism)
Boethusians
Second Temple Judaism
Synagogal Judaism
Therapeutae
Yudghanites
Zealots (Judea)
Sicarii
Kabbalah
Merkabah mysticism
Practical Kabbalah
Non-Rabbinic Judaism
Folk Judaism
Haymanot
Karaite Judaism
Qemant Judaism
Samaritanism
Rabbinic Judaism
Conservative Judaism ( Masorti Judaism)
Humanistic Judaism
Jewish Renewal
Orthodox Judaism
Carlebach movement
Haredi Judaism (a.k.a. ultra-Orthodox)
Dor Daim
Hardal
Haredi burqa sect
Hasidic Judaism
Misnagdim
Sephardic Haredi
Modern Orthodox Judaism
Open Orthodox Judaism
Musar movement
Zionism
Religious Zionism
Reconstructionist Judaism
Reform Judaism
Other Abrahamic
Bábism
Azali
Baháʼí Faith
Caravan of East and West
Free Baháʼís
Orthodox Baháʼí Faith
Druze
Mandaeism
Iranian religions
Manichaeism
Athinganoi (Historical)
Chinese Manichaeism
Yazdânism
Ishikism
Shabakism
Yarsanism
Yazidism
Zoroastrianism
Behafaridians (Historical)
Ilm-e-Khshnoom
Sepasian (Historical)
Khurramites (Historical)
Mazdakism (Historical)
Mazdaznan
Zurvanism
Blagovery
Indigenous (ethnic, folk) religions
Religions that consist of the traditional customs and beliefs of particular ethnic groups, refined and expanded upon for thousands of years, often lacking formal doctrine. Some adherents do not consider their ways to be "religion", preferring other cultural terms. Many indigenous religions incorporate forms of Animism, Totemism and Shamanism.
African
Traditional African
ǃKung religion
Abwoi religion
Acholi religion
Afizere traditional religion
Akan religion
Asante religion
Azande traditional religion
Bafia religion
Baka traditional religion
Bantu religion
Abagusii religion
Akamba traditional religion
AmaMpondomise traditional religion
Badimo
Balondo religion
Baluba religion
Bamileke religion
Bamum traditional religion
Banyole traditional beliefs
Bubi spirituality
Bushongo religion
Bwiti
Chaga faith
Chokwe spiritual beliefs
Duala traditional religion
Fipa religion
Furiiru traditional religion
Giriama traditional religion
Herero traditional faith
Himba religion
Kikuyu traditional religion
Kongo religion
Kwe faith
Lozi religion
Luvale religion
Makua traditional religion
Mbole religion
Nyakyusa religion
Ovambo traditional religion
Pedi traditional religion
Songye religion
Suku religion
Swazi traditional religion
Tonga religion
Tsonga traditional religion
Tumbuka religion
Xhosa traditional religion
Zulu traditional religion
Baoule traditional religion
Bari traditional religion
Bassa traditional religion
Biri traditional religion
Bobo religion
Bori
Bwa religion
Chamba traditional religion
Dahomean religion
Damara religion
Dan religion
Dinka religion
Dogon religion
Ebira traditional religion
Edo traditional religion
Efik religion
Ekoi religion
Esan traditional religion
Fali traditional religion
Frafra beliefs
Gbagyi traditional religion
Hadza religion
Hyel
Idoma traditional religion
Ijaw traditional religion
Inam
Jola traditional religion
Asisian religion
Khoekhoen religion
Kissi traditional religion
Kono traditional religion
Koore religion
Krahn religion
Kuku traditional beliefs
Lobi animism
Lotuko ethnic religion
Lugbara religion
Maasai religion
Madi traditional religion
Manjak religion
Mbuti religion
Moba ethnic religion
Mursi animism
Nso religion
Nuer religion
Nyongo Society
Bakossi beliefs
Odinala / Odinani
Oropom religion
Safwa religion
Samburu religion
San religion
N'um
Serer religion
Sidama religion
Surma religion
Tammari traditional religion
Temne traditional religion
Traditional Berber religion
Turkana traditional religion
Urhobo traditional religion
Vodun
Waaqeffanna
Yoruba religion
Ifá
Indigenous religion in Zimbabwe
Shona traditional religion
Diasporic African
Abakuá
Arara religion
Batuque
Candomblé
Candomblé Bantu
Candomblé Jejé
Candomblé Ketu
Comfa
Convince
Cuban Vodú
Dominican Vudú
Espiritismo
Haitian Vodou
Hoodoo
Kélé
Kumina
Louisiana Voodoo
Montamentu
Myal
Obeah
Palo
Quimbanda
Santería
Tambor de Mina
Trinidad Orisha
Umbanda
Winti
Saramaka religion
Altaic
Evenki shamanism
Manchu shamanism
Turko-Mongolic religion
Altaic shamanism
Burkhanism
Dukha shamanism
Mongolian shamanism
Black shamanism
Tengrism
Aiyy
Tengir Ordo
Vattisen Yaly
Nanai shamanism
Oroqen shamanism
Shor shamanism
Soyot shamanism
Ulch shamanism
Yakut shamanism
American
Abenaki religion
Ache religion
Akawaio religion
Alaska Native religions
Alaskan shamanism
Inuit religion
Tanana shamanism
Yupik shamanism
Yuit shamanism
Sirenik shamanism
Andoque religion
Anishinaabe beliefs
Ojibwe beliefs
Midewiwin
Wabunowin
Apache religion
Arhuaco spirituality
Atacama religion
Blackfoot religion
Bororo totemism
Caddo religion
Californian religions
Achomawi religion
Acjachemen religion
Cahuilla religion
Hupa beliefs
Kuksu
Cahto religion
Esselen beliefs
Miwok religion
Ohlone religion
Pomo religion
Kumeyaay beliefs
Northern Paiute beliefs
Mohave religion
Wiyot religion
Calusa religion
Chaná religion
Chilote religion
Choctaw religion
Croatan beliefs
Crow religion
Fuegian religion
Selk'nam religion
Garifuna spirituality
Guarani religion
Guarayos beliefs
Guayupe religion
Gwich'in beliefs
Haida religion
Ho-Chunk religion
Huaorani religion
Hupda cosmgony
Inca religion
Aymara religion
Chauvin religion
Nazca religion
Taki Unquy
Wari' beliefs
Illinois religion
Innu religion
Iroquois religion
Cherokee beliefs
Four Mothers Society
Keetoowah Society
Mohawk religion
Muscogee Creek religion
Seneca religion
Wyandot religion
Jivaroan religion
Achuar religion
Aguaruna religion
Shuar shamanism
Karankawa religion
Kayabi religion
Kalapalo beliefs
Kalinago religion
Kichwa religion
Kogi religion
Kuikoro religion
Kwakwakaʼwakw religion
Lenape religion
Lokono religion
Maleku beliefs
Mandan religion
Mapuche religion
Marajoara religion
Matses beliefs
Mesoamerican religion
Aztec religion
Classical Veracruz religion
Cora religion
Huichol religion
Lencan religion
Maya religion
Chuj religion
Cult of The Talking Cross
Huastec religion
Lacandon religion
Mazatec religion
Maximon
Mopan religion
Pech religion
Q'eqchi' religion
Tzeltal religion
Tzotzil religion
Tzʼutujil religion
Mixe religion
Nagualism
Olmec religion
Purépecha religion
Talamancan religion
Teotihuacan religion
Tepehuan beliefs
Tlapanec religion
Totonac religion
Zapotec religion
Mi'kmaq religion
Old Miskito religion
Muisca religion
Muzo religion
Navajo beliefs
Nuu-chah-nulth religion
Omaha religion
Osage spirituality
Pawnee religion
Parakanã shamanism
Pech religion
Pemon religion
Penobscot spirituality
Pericues religion
Piaroa religion
Powhatan religion
Pueblo religion
Acoma Pueblo religion
Hopi beliefs
Zuni religion
Ancestral Pueblo religion (Basketmaker III) (Pueblo II) (Pueblo III) (Pueblo IV)
Puruhá religion
Q'ero beliefs
Quechua beliefs
Rikbaktsa beliefs
Salish narratives
Seminole religion
Seri religion
Sioux religion
Assiniboine religion
Lakota religion
Wocekiye
Southeastern Ceremonial Complex (religion of the Mississippian culture)
Taensa religion
Taino spirituality
Tairona religion
Tapirape shamanism
Tehuelche religion
Ticuna shamanism
Toba religion
Tlingit religion
Tsimshian religion
Ute religion
Wai-Wai religion
Wapishana religion
Warao religion
Washat Dreamers Religion
Wayuu religion
Western Shoshone religion
Yaqui religion
Yaruro religion
Austroasiatic
Asur religion
Birhor traditional religion
Bru religion
Đạo Lương
Đạo Mẫu
Four Palaces
Thánh Trần worship
Ka Niam Khasi
Mon religion
Muong ethnic religion
Nicobarese traditional religion
Nocte religion
Ka Niamtre
Paoch animism
Sari Dharam
Sarnaism
Senoi ethnic religion
Sora traditional beliefs
Tampuan animism
Ta Oi animism
Wancho religion
Austronesian
Amis native religion
Aliran Kepercayaan/Mythology of Indonesia
Adat Pu'un
Aluk
Batak Parmalim
Dayak religion
Kaharingan
Jingi Tiu
Kejawèn
Kapitayan
Kangeanese religion
Karo Pemena
Kendayan religion
Marapu
Rejang religion
Rotenese religion
Saminism Movement
Sangirese religion
Sumbawa religion
Sundanese Wiwitan
Wai Apu religion
Dayawism
Batak folk religion
Bicolano religion
Blaan folk religion
Capiznon folk religion
Cuyunon folk religion
Gaddang folk religion
Ifugao folk religion
Ilocano folk religion
Itneg folk religion
Kalinga folk religion
Kankanaey folk religion
Karay-a folk religion
Mangyan folk religion
Palawan folk religion
Pangasinan folk religion
Sama Bajau folk religion
Sambal folk religion
Subanon folk religion
Tagalog folk religion
Tagbanwa folk religion
Pulahan
Tboli folk religion
Teduray folk religion
Visayan folk religion
Fomba Gasy
Jarai religion
Kanakanavu native religion
Malaysian folk religion
Datuk Keramat
Jakun religion
Pengarap Iban
Melanau religion
Momolianism
Murut religion
Orang Kanaq religion
Orang Seletar religion
Semai religion
Semaq Beri religion
Temuan religion
Micronesian religion
Carolinian religion
Chamorro religion
Chuukese religion
Nauruan indigenous religion
Polynesian narrative
Cook Islands narrative
Hawaiian religion
Mangarevan narrative
Māori religion
Niuean narrative
Rapa Nui narrative
Samoan narrative
Tahitian narrative
Tongan narrative
Tuvaluan narrative
Paiwan shamanism
Sakizaya native religion
Taivoan animism
Tao native religion
Caucasian
Khabzeism
Vainakh religion
Dravidian
Khond traditional religion
Kota religion
Koyapunem
Sauria Paharia religion
Tamil religion
Toda religion
Indo-European
Kalashism
Nagpuria religion
Ossetian native religion
Punjabi folk religion
Tharu religion
Koreanic and Japonic
Koshintō (Historical)
Matagi spirituality
Shinto
Shinbutsu-shugo
Gion cult
Fujiko
Rokugō Manzan
Sect Shinto
Fukko
Taikyō
Izumo-taishakyo
Jingukyo
Juka
Suika
Taiseikyō
Konkōkyō
Ontake-kyō
Oomoto
Kurozumikyō
Shugendō
Shrine Shinto
Association of Shinto Shrines
Kokugaku
State Shinto
Muism
Gasin faith
Ryukyuan religion
Melanesian and Aboriginal
Australian Aboriginal spirituality
Gamilaraay dreaming
Larrakia dreaming
Tasmanian Aboriginal spirituality
Yolnu religion
Fijian ancient religion
Kanak traditional beliefs
Papuan religion
Dumo spirituality
Fore traditional beliefs
Kaluli religion
Korowai religion
Trobriand traditional beliefs
Urapmin traditional beliefs
Negrito
Aeta religion
Ati animism
Onge native religion
Semang animism
Vedda original religion
Paleosiberian
Ainu religion
Koryak religion
Itelmen religion
Nivkh traditional religion
Yukaghir shamanism
Sino-Tibetan
Banrawat religion
Bathouism
Benzhuism
Biate animism
Bimoism
Bon
Dongba
Hangui
Burmese folk religion
Lisu religion
Chang Naga animism
Chutia religion
Chinese folk religion
Ancestor Worship
Chinese folk religion in Southeast Asia
Faism
Mazu worship
Northeast China folk religion
Queen Mother worship
Shangdiism
Shendao
Taiwanese folk beliefs
Wang Ye worship
Wuism
Jurchen/Qing shamanism
Ming shamanism
Xínghaode
Daba
Dingba
Donyi-Polo
Songsarek
Gurung shamanism
Hani religion
Hnam Sakhua
Jingpo religion
Kan Khwan
Karbi religions
Karen animism
Kiratism
Yumaism
Krama
Maring beliefs
Miji animism
Mizo religion
Mro religion
Nuo folk religion
Nyezi-No
Qiang folk religion
Reang religion
Sanamahism
Tangsa Naga animism
Rangfrah
Tingkao Ragwang Chapriak
Toto nature religion
Zahv
Tai and Miao
Hlai animism
Kev Dab Kev Qhuas
Kam religion
Maonan traditional religion
Mo
Pa Then religion
Qabiao religion
Satsana Phi
Ahom religion
Giay animism
Lamet religion
Nung religion
Saek religion
Sui religion
Then
Uralic
Komi shamanism
Mari Native Religion
Other
Beduin shamanism
Burusho shamanism
New religious movements
Religions that cannot be classed as either world religions or traditional folk religions, and are usually recent in their inception. Non-cargo cults are generally excluded from this list, see list of cults for cults
Cargo cults
John Frum
Johnson cult
Pomio Kivung
Prince Philip Movement
Vailala Madness
New ethnic religions
Black
African Zionism
Ausar Auset Society
Black Muslims
American Society of Muslims
Dini Ya Msambwa
Five-Percent Nation
Godianism
Hauka
Igbe religion
Moorish Science Temple of America
Moorish Orthodox Church of America
Movement for the Restoration of the Ten Commandments of God
Mumboism
Mungiki
Nation of Islam
United Nation of Islam
Nuwaubian Nation
Black Hebrew Israelites
African Hebrew Israelites of Jerusalem
Church of God and Saints of Christ
Commandment Keepers
Israelite Church of God in Jesus Christ
Israelite School of Universal Practical Knowledge
Nation of Yahweh
One West Camp
Rastafari
Bobo Ashanti
Nyabinghi
Twelve Tribes of Israel
White
Creativity
Fascist Occultism
Ariosophy
Esoteric Nazism
Evolaism
Fascist mysticism
Nazi Occultism
Statolatry
Israelism
British Israelism
Christian Identity
French Israelism
Nordic Israelism
Order of Nine Angles
Völkisch movement
German Faith Movement
Wotansvolk
Native American
Ghost Dance
Indian Shaker Church
Longhouse Religion
Mexicayotl
Native American Church
Big Moon Peyotism
Wasshat religion
World religion-derived new religions
Abrahamic-derived
Antoinism
Beili Wang
Branch Davidians
Chapel of Russia's Resurrection
Chrislam
Christian Science
Creation Spirituality
Daheshism
Eastern Lightning
Faizrakhmanist
The Family International
Gafatar
Grail Movement
Holy Spirit of Blood and Water Church
Koreshanity
Lalpa Kohran Thar
Last Testamentism
Mama Tata
Mentuhui
Modekngei
Noahidism
Pai Marire
Pilgrims of Ares
Rātana
Ringatu
Soldiers of Heaven
Spiritism
Unification Church
Unification Church of the United States
Urantia movement
World Elijah Evangelical Mission
World Mission Society Church of God
Zhushenjiao
Chinese salvationist religions
Baguadao ("Way of the Eight Trigrams")
Dejiao ("Teaching of Virtue")
Huangjidao ("Way of the Imperial Pole")
Huangtiandao ("Way of the Yellow Sky")
Huazhaidao ("Way of Flowers and Fasting")
Jiugongdao ("Way of the Nine Palaces")
Luandao ("Phoenix Way")
Luoism ("Way of Luo")
Chinese religions of fasting
Xiantiandao ("Way of Former Heaven")
Guiyidao ("Way of the Return to the One")
Shengdao ("Holy Way")
Yaochidao ("Way of the Mother of Pearl Lake")
Yiguandao ("Persistent Way")
Haizidao
Yixin Tiandao ("Heart-bound Heavenly Way")
Dacheng
Hongyangism
Maitreyanism
Sanban Puren Pai
Sanyiism
Shanrendao ("Way of the Virtuous Man")
Taigu school
Tiandihui
Tiandiism
Tianguangdao ("Way of the Heavenly Light")
Tianxian Miaodao ("Way of the Temple of the Heavenly Immortals")
Weixinism
White Lotus
Xuanyuandao ("Way of Xuanyuan")
Yellow Sand Society
Zailiism ("Way of the Abiding Principle)
Zhongyongdao ("Way of the Golden Mean")
Hindu reform movements
Adidam
Adi Dharm
Brahmoism
Brahmo Samaj
Sadharan Brahmo Samaj
Ananda
Ananda Ashrama
Ananda Marga
Arya Samaj
Ayyavazhi
Chinmaya Mission
Hare Krishna
Mahanam Sampraday
Mahima Dharma
Matua Mahasangha
Oneness Movement
Rajneesh movement
Satsang
Shirdi Sai Baba movement
Sivananda Yoga Vedanta Centres
Sri Aurobindo Ashram
Sri Ramana Ashram
Neo-Advaita
Swaminarayan Sampradaya
Bochasanwasi Akshar Purushottam Swaminarayan Sanstha
Laxmi Narayan Dev Gadi
International Swaminarayan Satsang Mandal
Swaminarayan Gurukul
Nar Narayan Dev Gadi
International Swaminarayan Satsang Organisation
Narnarayan Dev Yuvak Mandal
Swaminarayan Gadi (Maninagar)
Swaminarayan Mandir Vasna Sanstha
Transcendental Meditation
Muist-derived
Cheondoism
Jeungsanism
Bocheonism
Daesun Jinrihoe
Jeung San Do
Suwunism
Daejongism
Victory Altar
Neo-Buddhism
Đạo Bửu Sơn Kỳ Hương
Hòa Hảo
Tứ Ân Hiếu Nghĩa
Diamond Way Buddhism
Falun Gong
Guanyin Famen
Humanistic Buddhism
Navayana
New Kadampa Tradition
Nipponzan-Myōhōji-Daisanga
PL Kyodan
Reiyūkai
Risshō Kōsei Kai
Rimé movement
Shambhala Buddhism
Shinnyo-en
Soka Gakkai
Triratna Buddhist Community
True Buddha School
Won Buddhism
Perennial and interfaith
Anandamayee Sangha
Bell religion
Brahma Kumaris
Caodaism
Coconut religion
Đạo Dừa
Living Interfaith
Meivazhi
Moorish Orthodox Church of America
Omnism
Open-source religion
Satya Dharma
Sathya Sai Baba movement
Share International
Subud
Shinshukyo
Aum Shinrikyo
Aleph
Hikari no Wa
Church of World Messianity
Dōkai
Gedatsukai
Happy Science
Higashikuni-kyo
Ijun
Kenshōkai
Kokuchukai
Mahikari
Myōdōkai Kyōdan
Nipponzan-Myōhōji-Daisanga
Shinreikyo
Shōroku Shintō Yamatoyama
Shumei
Shingaku
Shinmeiaishinkai
Shōshinkai
Tenrikyo
Tenrin-Ō Meisei Kyōdan
Honmichi
Honbushin
Sekai Shindokyo
Daehan Cheolligyo
Tenshō Kōtai Jingūkyō
Zenrinkyo
Sikh-derived
Contemporary Sant Mat movements
Advait Mat
Radha Soami
Radha Soami Satsang Beas
Radha Soami Satsang Dayagbal
Radha Swami Satsang, Dinod
Ruhani Satsang
Manavta Mandir
Science of Spirituality (a.k.a. Sawan Kirpal Ruhani Mission)
Radha Soami-influenced
Ancient Teachings of the Masters
Dera Sacha Sauda
Eckankar
Elan Vital (formerly Divine Light Mission)
Movement of Spiritual Inner Awareness
Ravidassia
Modern paganism
Ethnic neopaganism
Baltic neopaganism
Dievturība
Romuva
Caucasian neopaganism
Abkhaz neopaganism
Assianism
Celtic neopaganism
Celtic reconstructionist paganism
Druidry
Ár nDraíocht Féin
Order of Bards, Ovates, and Druids
Reformed Druids of North America
Church of the Guanche People
Heathenry (a.k.a. Germanic neopaganism)
Hellenism
Heraka
Hetanism
Italo-Roman neopaganism
Nova Roma
Roman Traditional Movement
Kemetism
Kemetic Orthodoxy
Semitic neopaganism
Rodnovery (a.k.a. Slavic neopaganism)
Native Polish Church
Peterburgian Vedism
Rodzima Wiara
Rodnover Confederation
Sylenkoism
Slavic shamanism
Union of Slavic Native Belief Communities
Ynglism
Uralic neopaganism
Estonian neopaganism
Suomenusko
Hungarian neopaganism
Mastorava
Udmurt Vos
Zalmoxianism
Zuism
Syncretic neopaganism
Adonism
Brauchau
Christopaganism
Christian Wicca
Church of All Worlds
Cochrane's Craft
Huna
Ivanovism
Krama
Nature religion
Neoshamanism
Urban shamanism
Radical Faeries
Ringing Cedars' Anastasianism
Stregheria
Summum
Technopaganism
Temple of Priapus
Wicca
British Traditional Wicca
Alexandrian Wicca
Algard Wicca
Blue Star Wicca
Central Valley Wicca
Chthonioi Alexandrian Wicca
Gardnerian Wicca
Celtic Wicca
Faery Wicca
Feri Tradition
Georgian Wicca
Odyssean Wicca
Seax-Wica
Universal Eclectic Wicca
Wiccan Churches
Goddess religions
Church of Aphrodite
Feraferia
Goddess Wicca
Covenant of the Goddess
Dianic Wicca
Faerie faith
Reclaiming
Entheogenic religions
Church of the Universe
Healing Church in Rhode Island
Neo-American Church
Santo Daime
Temple of the True Inner Light
Tensegrity
THC Ministry
União do Vegetal
New Age Movement
Association for Research and Enlightenment
Church Universal and Triumphant
Rainbow Family
The Infinite Way
New Thought
Church of Divine Science
Church of the Truth
Home of Truth
Jewish Science
Psychiana
Religious Science
Seicho-no-Ie
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Alchemy
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References
Sources
External links
Maoz, Zeev; Henderson, Errol A. (2013). "The World Religion Dataset, 1945–2010: Logic, Estimates, and Trends". International Interactions. 39 (3): 265–291.
Statistics on religious belief or adherence
BBC.co.uk section on major world religions
Cults
Dynamic lists
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Religion-related lists
Spirituality | List of religions and spiritual traditions | Biology | 9,085 |
44,966,748 | https://en.wikipedia.org/wiki/Hydnellum%20cyanodon | Hydnellum cyanodon is a rare species of tooth fungus in the family Bankeraceae. Found in Boularderie Island and Antigonish County (Nova Scotia, Canada), it was described as new to science in 1964 by Canadian mycologist Kenneth A. Harrison. The turbinate (cushion-shaped) cap of the fruitbody measures in diameter. Spines on the cap underside up to 5 mm long, and blue in color. The fungus fruits singly or in groups in deep moss under spruce trees.
References
External links
Fungi described in 1964
Fungi of North America
Inedible fungi
cyanodon
Fungus species | Hydnellum cyanodon | Biology | 129 |
38,266,311 | https://en.wikipedia.org/wiki/U.S.A.%20%28painting%29 | U.S.A. is a trompe-l'œil oil painting by American artist John Haberle from 1889, located in the Indianapolis Museum of Art, which is in Indianapolis, Indiana. It depicts currency and stamps so realistically that Haberle was accused of pasting real money to the canvas.
Description
U.S.A. depicts a scattering of worn American stamps and bills, particularly the back of a dollar bill emblazoned with a warning against reproducing it. In a wry touch, Haberle also painted on a newspaper clipping praising one of his earlier works. U.S.A. is signed in the upper right corner with "J. Haberle" and a smiley face, and again on the metal plate on front of the shadow box frame, which Haberle painted to look engraved.
Historical information
In 1886, William Harnett, another noted photorealistic painter, was arrested for counterfeiting. This apparently inspired Haberle to produce an abundance of exact facsimiles of American currency, particularly in his first four years as a painter, from 1887 to 1891. Haberle originally trained as an engraver, which helped prepare him for his particular artistic calling. Despite warnings from the Secret Service, Haberle persisted in producing such images in his particularly wry manner.
While governmental rebukes only encouraged Haberle to greater productivity, the accusation of trickery enraged him. When U.S.A. was first exhibited at the Art Institute of Chicago, a newspaper critic declared that the artist must have used actual money and stamps. Haberle immediately traveled to Chicago and, armed with magnifying glass, paint remover, and art experts, categorically proved that the canvas was covered only in oil paint.
Location history
It was a display of Harnett's work in a New York saloon that led to his brush with the Secret Service and rapid retreat from currency-themed art. Haberle, however, sold U.S.A. to Marvin Preston, manager of Churchill's Saloon in Detroit, where it hung unmolested. That setting was typical for trompe-l'œil paintings, which tended to have masculine themes like money and hunting trophies and reside in manly places like bars. His grandson, also Marvin Preston, donated it to the Sally Turner Gallery in Plainfield, New Jersey.
Acquisition
U.S.A. was a gift from Paul and Ruth Buchanan of Indianapolis in 2002. It is currently on view in the Paine Turn of the Century American Art Gallery and has the acquisition number 2002.225.
References
External links
IMA page.
1889 paintings
Optical illusions
American paintings
Paintings in the Indianapolis Museum of Art
Banknotes of the United States | U.S.A. (painting) | Physics | 564 |
5,668,570 | https://en.wikipedia.org/wiki/Trisaccharide | Trisaccharides are oligosaccharides composed of three monosaccharides with two glycosidic bonds connecting them. Similar to the disaccharides, each glycosidic bond can be formed between any hydroxyl group on the component monosaccharides. Even if all three component sugars are the same (e.g., glucose), different bond combinations (regiochemistry) and stereochemistry (alpha- or beta-) result in trisaccharides that are diastereoisomers with different chemical and physical properties.
Examples
References
External links | Trisaccharide | Chemistry | 131 |
11,404,339 | https://en.wikipedia.org/wiki/Daniel%20Mastretta | Juan Daniel Mastretta Guzmán (born 1953, Puebla) is a Mexican engineer and designer. In 1987 he founded Mastretta Design, a design and automotive company. Mastretta was chiefly responsible for the development of the first Mexican sports car, the Mastretta MXT, in 2008.
Daniel Mastretta trained in industrial design, and in his early career worked primarily in furniture and packaging design and in the design of public spaces. However, his primary work has been in the public transport sector. One of the founders of the Mexican design companies, Tecnoidea and CV/Tecnosport, he has been the chief designer of 17 different models of buses (both in Mexico and abroad). In 1997 he was awarded the Premio al Mérito Profesional in design by the Colegio de Diseñadores Industriales y Gráficos de México (College of Industrial and Graphic Designers of Mexico).
References
Living people
1953 births
Automotive engineers
Mexican people of Italian descent
Mexican designers
Mexican mechanical engineers | Daniel Mastretta | Engineering | 207 |
65,820,116 | https://en.wikipedia.org/wiki/13%20Ceti | 13 Ceti is a triple star system in the equatorial constellation of Cetus. It is dimly visible to the naked eye with a combined apparent visual magnitude of 5.20. The system is located at a distance of approximately 69 light years from the Sun based on stellar parallax, and is drifting further away with a radial velocity of +10.4 km/s. It shares a common motion with the Hyades moving group, although it is too old to be a member.
This star was identified as a visual binary system by G. W. Hough in 1844 and given the identifier HO 212. The pair have an orbital period of and an eccentricity of 0.77. The brighter member, designated component A, is an F-type main-sequence star with a stellar classification of F6 V and a visual magnitude of 5.61. It appears to have an active chromosphere and is classified as an RS Canum Venaticorum variable with a variable star designation of BU Cet. The star was detected as a source of soft X-ray emission by EXOSAT. It has 18% more mass than the Sun and is estimated to be about four billion years old.
In 1907, E. B. Frost discovered the primary is a spectroscopic binary, making this a triple star system. This is a double-lined spectroscopic binary with a period of 2.1 days and a circularized orbit. The companion signature was confirmed using the separated fringe packet technique with the CHARA array. It is most likely a K-type main-sequence star with a class of K3.5 V and 70% of the mass of the Sun.
The secondary member of the visual binary, designated component B, is a G-type main-sequence star with a class of G4 V. It has 90% of the Sun's mass and a visual magnitude of 6.90. A distant visual companion to this system was detected by S. W. Burnham in 1877. Designated component C, this star is a background object of magnitude 12.50. As of 1999, it was located at an angular separation of from the primary along a position angle of 322°.
References
F-type main-sequence stars
G-type main-sequence stars
K-type main-sequence stars
RS Canum Venaticorum variables
Triple stars
Spectroscopic binaries
Cetus
BD-04 0062
Ceti, 13
0023
003196
002762
0142
Ceti, BE | 13 Ceti | Astronomy | 515 |
249,992 | https://en.wikipedia.org/wiki/Binary%20logarithm | In mathematics, the binary logarithm () is the power to which the number must be raised to obtain the value . That is, for any real number ,
For example, the binary logarithm of is , the binary logarithm of is , the binary logarithm of is , and the binary logarithm of is .
The binary logarithm is the logarithm to the base and is the inverse function of the power of two function. There are several alternatives to the notation for the binary logarithm; see the Notation section below.
Historically, the first application of binary logarithms was in music theory, by Leonhard Euler: the binary logarithm of a frequency ratio of two musical tones gives the number of octaves by which the tones differ. Binary logarithms can be used to calculate the length of the representation of a number in the binary numeral system, or the number of bits needed to encode a message in information theory. In computer science, they count the number of steps needed for binary search and related algorithms. Other areas
in which the binary logarithm is frequently used include combinatorics, bioinformatics, the design of sports tournaments, and photography.
Binary logarithms are included in the standard C mathematical functions and other mathematical software packages.
History
The powers of two have been known since antiquity; for instance, they appear in Euclid's Elements, Props. IX.32 (on the factorization of powers of two) and IX.36 (half of the Euclid–Euler theorem, on the structure of even perfect numbers).
And the binary logarithm of a power of two is just its position in the ordered sequence of powers of two.
On this basis, Michael Stifel has been credited with publishing the first known table of binary logarithms in 1544. His book Arithmetica Integra contains several tables that show the integers with their corresponding powers of two. Reversing the rows of these tables allow them to be interpreted as tables of binary logarithms.
Earlier than Stifel, the 8th century Jain mathematician Virasena is credited with a precursor to the binary logarithm. Virasena's concept of ardhacheda has been defined as the number of times a given number can be divided evenly by two. This definition gives rise to a function that coincides with the binary logarithm on the powers of two, but it is different for other integers, giving the 2-adic order rather than the logarithm.
The modern form of a binary logarithm, applying to any number (not just powers of two) was considered explicitly by Leonhard Euler in 1739. Euler established the application of binary logarithms to music theory, long before their applications in information theory and computer science became known. As part of his work in this area, Euler published a table of binary logarithms of the integers from 1 to 8, to seven decimal digits of accuracy.
Definition and properties
The binary logarithm function may be defined as the inverse function to the power of two function, which is a strictly increasing function over the positive real numbers and therefore has a unique inverse.
Alternatively, it may be defined as , where is the natural logarithm, defined in any of its standard ways. Using the complex logarithm in this definition allows the binary logarithm to be extended to the complex numbers.
As with other logarithms, the binary logarithm obeys the following equations, which can be used to simplify formulas that combine binary logarithms with multiplication or exponentiation:
For more, see list of logarithmic identities.
Notation
In mathematics, the binary logarithm of a number is often written as . However, several other notations for this function have been used or proposed, especially in application areas.
Some authors write the binary logarithm as , the notation listed in The Chicago Manual of Style. Donald Knuth credits this notation to a suggestion of Edward Reingold, but its use in both information theory and computer science dates to before Reingold was active. The binary logarithm has also been written as with a prior statement that the default base for the logarithm is . Another notation that is often used for the same function (especially in the German scientific literature) is , from Latin logarithmus dualis or logarithmus dyadis.
The , ISO 31-11 and ISO 80000-2 standards recommend yet another notation, . According to these standards, should not be used for the binary logarithm, as it is instead reserved for the common logarithm .
Applications
Information theory
The number of digits (bits) in the binary representation of a positive integer is the integral part of , i.e.
In information theory, the definition of the amount of self-information and information entropy is often expressed with the binary logarithm, corresponding to making the bit the fundamental unit of information. With these units, the Shannon–Hartley theorem expresses the information capacity of a channel as the binary logarithm of its signal-to-noise ratio, plus one. However, the natural logarithm and the nat are also used in alternative notations for these definitions.
Combinatorics
Although the natural logarithm is more important than the binary logarithm in many areas of pure mathematics such as number theory and mathematical analysis, the binary logarithm has several applications in combinatorics:
Every binary tree with leaves has height at least , with equality when is a power of two and the tree is a complete binary tree. Relatedly, the Strahler number of a river system with tributary streams is at most .
Every family of sets with different sets has at least elements in its union, with equality when the family is a power set.
Every partial cube with vertices has isometric dimension at least , and has at most edges, with equality when the partial cube is a hypercube graph.
According to Ramsey's theorem, every -vertex undirected graph has either a clique or an independent set of size logarithmic in . The precise size that can be guaranteed is not known, but the best bounds known on its size involve binary logarithms. In particular, all graphs have a clique or independent set of size at least and almost all graphs do not have a clique or independent set of size larger than .
From a mathematical analysis of the Gilbert–Shannon–Reeds model of random shuffles, one can show that the number of times one needs to shuffle an -card deck of cards, using riffle shuffles, to get a distribution on permutations that is close to uniformly random, is approximately . This calculation forms the basis for a recommendation that 52-card decks should be shuffled seven times.
Computational complexity
The binary logarithm also frequently appears in the analysis of algorithms, not only because of the frequent use of binary number arithmetic in algorithms, but also because binary logarithms occur in the analysis of algorithms based on two-way branching. If a problem initially has choices for its solution, and each iteration of the algorithm reduces the number of choices by a factor of two, then the number of iterations needed to select a single choice is again the integral part of . This idea is used in the analysis of several algorithms and data structures. For example, in binary search, the size of the problem to be solved is halved with each iteration, and therefore roughly iterations are needed to obtain a solution for a problem of size . Similarly, a perfectly balanced binary search tree containing elements has height .
The running time of an algorithm is usually expressed in big O notation, which is used to simplify expressions by omitting their constant factors and lower-order terms. Because logarithms in different bases differ from each other only by a constant factor, algorithms that run in time can also be said to run in, say, time. The base of the logarithm in expressions such as or is therefore not important and can be omitted. However, for logarithms that appear in the exponent of a time bound, the base of the logarithm cannot be omitted. For example, is not the same as because the former is equal to and the latter to .
Algorithms with running time are sometimes called linearithmic. Some examples of algorithms with running time or are:
Average time quicksort and other comparison sort algorithms
Searching in balanced binary search trees
Exponentiation by squaring
Longest increasing subsequence
Binary logarithms also occur in the exponents of the time bounds for some divide and conquer algorithms, such as the Karatsuba algorithm for multiplying -bit numbers in time ,
and the Strassen algorithm for multiplying matrices in time
. The occurrence of binary logarithms in these running times can be explained by reference to the master theorem for divide-and-conquer recurrences.
Bioinformatics
In bioinformatics, microarrays are used to measure how strongly different genes are expressed in a sample of biological material. Different rates of expression of a gene are often compared by using the binary logarithm of the ratio of expression rates: the log ratio of two expression rates is defined as the binary logarithm of the ratio of the two rates. Binary logarithms allow for a convenient comparison of expression rates: a doubled expression rate can be described by a log ratio of , a halved expression rate can be described by a log ratio of , and an unchanged expression rate can be described by a log ratio of zero, for instance.
Data points obtained in this way are often visualized as a scatterplot in which one or both of the coordinate axes are binary logarithms of intensity ratios, or in visualizations such as the MA plot and RA plot that rotate and scale these log ratio scatterplots.
Music theory
In music theory, the interval or perceptual difference between two tones is determined by the ratio of their frequencies. Intervals coming from rational number ratios with small numerators and denominators are perceived as particularly euphonious. The simplest and most important of these intervals is the octave, a frequency ratio of . The number of octaves by which two tones differ is the binary logarithm of their frequency ratio.
To study tuning systems and other aspects of music theory that require finer distinctions between tones, it is helpful to have a measure of the size of an interval that is finer than an octave and is additive (as logarithms are) rather than multiplicative (as frequency ratios are). That is, if tones , , and form a rising sequence of tones, then the measure of the interval from to plus the measure of the interval from to should equal the measure of the interval from to . Such a measure is given by the cent, which divides the octave into equal intervals ( semitones of cents each). Mathematically, given tones with frequencies and , the number of cents in the interval from to is
The millioctave is defined in the same way, but with a multiplier of instead of .
Sports scheduling
In competitive games and sports involving two players or teams in each game or match, the binary logarithm indicates the number of rounds necessary in a single-elimination tournament required to determine a winner. For example, a tournament of players requires rounds to determine the winner, a tournament of teams requires rounds, etc. In this case, for players/teams where is not a power of 2, is rounded up since it is necessary to have at least one round in which not all remaining competitors play. For example, is approximately , which rounds up to , indicating that a tournament of teams requires rounds (either two teams sit out the first round, or one team sits out the second round). The same number of rounds is also necessary to determine a clear winner in a Swiss-system tournament.
Photography
In photography, exposure values are measured in terms of the binary logarithm of the amount of light reaching the film or sensor, in accordance with the Weber–Fechner law describing a logarithmic response of the human visual system to light. A single stop of exposure is one unit on a base- logarithmic scale. More precisely, the exposure value of a photograph is defined as
where is the f-number measuring the aperture of the lens during the exposure, and is the number of seconds of exposure.
Binary logarithms (expressed as stops) are also used in densitometry, to express the dynamic range of light-sensitive materials or digital sensors.
Calculation
Conversion from other bases
An easy way to calculate on calculators that do not have a function is to use the natural logarithm () or the common logarithm ( or ) functions, which are found on most scientific calculators. To change the logarithm base to 2 from , , or any other base , one can use the formulae:
Approximately,
Integer rounding
The binary logarithm can be made into a function from integers and to integers by rounding it up or down. These two forms of integer binary logarithm are related by this formula:
The definition can be extended by defining . Extended in this way, this function is related to the number of leading zeros of the 32-bit unsigned binary representation of , .
The integer binary logarithm can be interpreted as the zero-based index of the most significant bit in the input. In this sense it is the complement of the find first set operation, which finds the index of the least significant bit. Many hardware platforms include support for finding the number of leading zeros, or equivalent operations, which can be used to quickly find the binary logarithm. The fls and flsl functions in the Linux kernel and in some versions of the libc software library also compute the binary logarithm (rounded up to an integer, plus one).
Iterative approximation
For a general positive real number, the binary logarithm may be computed in two parts.
First, one computes the integer part, (called the characteristic of the logarithm).
This reduces the problem to one where the argument of the logarithm is in a restricted range, the interval , simplifying the second step of computing the fractional part (the mantissa of the logarithm).
For any , there exists a unique integer such that , or equivalently . Now the integer part of the logarithm is simply , and the fractional part is . In other words:
For normalized floating-point numbers, the integer part is given by the floating-point exponent, and for integers it can be determined by performing a count leading zeros operation.
The fractional part of the result is and can be computed iteratively, using only elementary multiplication and division.
The algorithm for computing the fractional part can be described in pseudocode as follows:
Start with a real number in the half-open interval . If , then the algorithm is done, and the fractional part is zero.
Otherwise, square repeatedly until the result lies in the interval . Let be the number of squarings needed. That is, with chosen such that is in .
Taking the logarithm of both sides and doing some algebra:
Once again is a real number in the interval . Return to step 1 and compute the binary logarithm of using the same method.
The result of this is expressed by the following recursive formulas, in which is the number of squarings required in the i-th iteration of the algorithm:
In the special case where the fractional part in step 1 is found to be zero, this is a finite sequence terminating at some point. Otherwise, it is an infinite series that converges according to the ratio test, since each term is strictly less than the previous one (since every ). See Horner's method. For practical use, this infinite series must be truncated to reach an approximate result. If the series is truncated after the -th term, then the error in the result is less than .
Software library support
The log2 function is included in the standard C mathematical functions. The default version of this function takes double precision arguments but variants of it allow the argument to be single-precision or to be a long double. In computing environments supporting complex numbers and implicit type conversion such as MATLAB the argument to the log2 function is allowed to be a negative number, returning a complex one.
References
External links
Feynman and the Connection Machine
Binary arithmetic
Calculus
Logarithms | Binary logarithm | Mathematics | 3,449 |
9,639,785 | https://en.wikipedia.org/wiki/Kuroshima%20Research%20Station | Kuroshima Research Station is a marine research institute in Okinawa, Japan, located on the island of Kuroshima. (黒島)
It was established in 1973 as the Yaeyama Marine Park Research Institute, for the purpose of managing and utilising the marine park area in Sekisei (石西) lagoon between Ishigaki (石垣) Island and Iriomote (西表) Island including Kuroshima Island.
From the beginning, it worked as ocean research station, and existed until 2002 under the financial support of Nagoya Railroad Business Operations Co. Ltd.
At present, Kuroshima Research Station belongs to the NPO Sea Turtle Association of Japan, which took over the activities of the institute.
Activities
Some of the institutes activities include 30 years’ research into the nesting of sea turtles, including confirmation of the nesting of the hawksbill sea turtle for the first time in Japan, and confirming the nesting of green sea turtles. They have also researched acanthasters and corals.
In 2005, they sponsored the Japanese Sea Turtle Conference, which is held every year at the location of sea turtles nesting rookeries in Japan.
References
External links
Sea Turtle Association of Japan
Japan Committee for IUCN
Mexican, Japanese and U.S. Fishermen Celebrate Sea Turtle's Epic Journey and Commit to Conservation
The nature of Yaeyama Islands
Turtle conservation organizations
Animal welfare organizations based in Japan
Environmental organizations based in Japan
Environmental organizations established in 1973
1973 establishments in Japan
Marine biology
Research institutes | Kuroshima Research Station | Biology | 299 |
34,255,168 | https://en.wikipedia.org/wiki/Stein%202051 | Stein 2051 (Gliese 169.1, G 175-034, LHS 26/27) is a nearby binary star system, containing a red dwarf (component A) and a degenerate star (white dwarf) (component B), located in constellation Camelopardalis at about 18 ly from Earth.
Stein 2051 is the nearest (red dwarf + white dwarf) separate binary system (40 Eridani BC is located closer at 16.26 light-years, but it is a part of a triple star system).
Stein 2051 B is the 6th nearest white dwarf after Sirius B, Procyon B, van Maanen's star, LP 145-141 and 40 Eridani B.
Properties
The brighter of these two stars is A (a red dwarf), but the more massive is component B (a white dwarf).
In 2017, Stein 2051 B was observed passing in front of a more distant star. The bending of starlight by the gravitational field of the nearer star allowed its mass to be directly measured. The estimated mass of Stein 2051 B is , which fits the expected range of a white dwarf with a carbon-oxygen core.
References
External links
(the whole system)
(component A)
(component B)
Camelopardalis
Binary stars
M-type main-sequence stars
White dwarfs
0169.1
J04311147+5858375
WISE objects
021088 | Stein 2051 | Astronomy | 299 |
58,621,893 | https://en.wikipedia.org/wiki/Epiroc | Epiroc AB is a Swedish manufacturer of mining and infrastructure equipment. It is headquartered in Stockholm, Sweden and has its manufacturing facilities in Sweden, the United States, Canada, Australia, China, India, Japan, and Germany.
History
Epiroc has its roots in Atlas Copco, which was founded in 1873 in Stockholm. It was created as a result of Atlas Copco's decision to split out its legacy business of mining equipment. Atlas Copco began to produce rock drills in 1905. In January 2017, Atlas Copco's board of directors decided to propose to the Annual General Meeting that the company be divided, and that the mining and infrastructure business be listed as its own separate company in 2018. Epiroc was officially created on 1 January 2018 and was subsequently listed on the Nasdaq Stockholm stock exchange on June 18, 2018.
Epiroc operates as 5 divisions focused on their respective application of mining engineering, digital products, and services & service support.
Surface
Underground
Parts & Services
Digital Solutions
Tools & Attachments
Products and services
Epiroc offers a product portfolio of drilling rigs, rock drilling tools, trucks & loaders, raise boring equipment, excavator attachments, rock excavation equipment, rock reinforcement tools & underground mine ventilation systems, and service agreements related to equipment maintenance. In 2022 it expanded into the field of hyperspectral imaging of core samples.
References
Swedish companies established in 2018
Manufacturing companies based in Stockholm
Mining equipment companies
Multinational companies headquartered in Sweden
Swedish brands
Companies listed on Nasdaq Stockholm
Manufacturing companies of Sweden | Epiroc | Engineering | 315 |
27,105,779 | https://en.wikipedia.org/wiki/Galala%20marble | Galala or Galalah is an Egyptian limestone extracted from a mountain called Galala located in Suez, Egypt. It was named of the trade name of this mountain "Galala Marble". Its colours are creamy and creamy white as its variations differ according to the quarry stones.
Galala Physical and mechanical characteristics:
Compressive strength kg/cm2 = 824.6
Tensile strength kg/cm2m = 111.6
Water absorption% = 0.12
Density kg/m3 = 2,627
See also
Galala Mountain
References
Limestone
Sinai Peninsula | Galala marble | Physics | 113 |
3,654,354 | https://en.wikipedia.org/wiki/Still%20room | The still room is a room for preparing household compounds, found in most great houses, castles or large establishments throughout Europe, dating back at least to medieval times. Stillrooms were used to make products as varied as candles, furniture polish, and soap; distillery was only one of the tasks carried out there.
The still room was a working room, part chemistry lab, part compounding pharmacy, part perfumery, part beverage factory, and part kitchen. Professional manufacturers such as dispensing chemists and apothecaries gradually took over many still-room tasks, producing the products of the still-room commercially. Its use for food preservation also declined with the commercialization of preserved food.
Medieval use
Originally, the still room was a very important part of the household. The lady of the house was in charge of the room, and she taught her daughters and wards some of the skills needed to run their own homes in order to make them more marriageable. As practical skills fell out of fashion for high-born women, the still room became the province of poor dependent relations.
Households relied on medieval food preservation, much of which was done in the stillroom, to provide varied food through the winter.
Medieval households also made many perfumes, such as rosewater, and powders made from orris root, lavender, and calamus; they also dried and used meadowsweet, germander, hyssop, rosemary, thyme, violet, and woodruff.
The literate hand-wrote their own collections of stillroom recipes, often mixed with other practical household knowledge. These receipt-books were often amended from experience, and were valued, and bequeathed in wills. While these books were very individual compilations, the recipes from these books largely remain similar during the medieval period; the contents changed little over the centuries. These collections were often collaborative, multi-authored collections of useful practical knowledge, a "family book" like a family Bible.
Renaissance use
A still room in a Renaissance great house would be equipped with distillation equipment, and a waist-high brazier or chafing dish. There might well be an adjoining stove room, with a small stove and slatted shelves for drying.
Spirits, wines, syrups, and waters were distilled. Other products included pickled vegetables and fruit, laundry recipes, remedies, and perfumes, and home-brewed beer or wine was often made. Herbs and flowers from the kitchen garden and surrounding countryside were preserved for flavoring food and processed tinctures, distillates, and syrups. Other products included ointments, soaps, furniture polishes, and a wide variety of medicines.
Sugar became widely available to the upper classes in the Renaissance. Renaissance houses made many sugary conceits, such as cordials (beverage syrups), comfits (candy-coated nuts and spices), spiced sugar candies, candied fruit and plants, preserved in syrups, fruit jellies, fruit conserves, quince pastes, marmalades, and crumb gingerbreads.
Printing meant that book availability, and literacy rates, rose. Stillroom recipes were more commonly written down (along with other information, like general food recipes, family medical histories, unit conversion tables, and encyclopedic lists, often all in the same book), by women and men of the houhold, including nobility and some literate servants, and bequeathed. These books (sometimes called "closets") were also copied, so that multiple siblings could have a copy, and friends and family sent one another individual recipes. Some receipt-books were also made to be published (see Still room#See also for a selection). Recipes from printed books were often copied into home-made manuscript collections, and recipes from manuscripts were collected for print, causing a drastic increase in the pace of innovation. Manuscript recipes change little from 1200 to 1500, but subsequently they change every 40–50 years.
During this period, medicines were increasingly purchased, not home-made.
Later uses
In later years, as physicians and apothecaries became more widely spread and the products of the still room became commercially available, the still room increasingly became an adjunct of the kitchen. The use of the still room gradually diminished to making only preserves, jellies, and home-brewed beverages, and it became a store room for perishables such as cakes.
The stillroom was used to make preserves including pickled eggs and vegetables, fermented vegetables and vinegars, dried foods, dried herbs and flowers, spice preparations, canned vegetables and chutneys, marmalades, and jams; beverages, such as tea, bottled drinks, and beer; and perfumes, candles, and home remedies. It was also used to prepare afternoon tea; not just the beverages, but sandwiches and cakes. The good china for tea was therefore also kept there.
The still room was staffed by the housekeeper or cook, then later by the still room maid, who also served afternoon tea.
As an annexe to public commercial kitchens
If beverages were not dispensed from food service counters, then the design of commercial kitchens in hotels and restaurants traditionally included a still room where tea, coffee and other beverages were prepared and dispensed. These would be located immediately adjacent to hotel lounges. Central in the still room would be a gas or electric water boiler and separate coffee brewers. Crockery, tea pots and coffee pots would also be stored here.
See also
Knowledge books, unpublished and published (most contemporary printings have long descriptive titles):
The Good Huswifes Jewell: Wherein is to be found most excellend and rare Deuises for conceites in Cookery, found out by the practise of Thomas Dawson: Wherevnto is adioyned sundry approued receits for many soueraine oyles, and the way to distill many precious waters, with diuers approued medicines for many diseases: Also certain approued points of husbandry, very necessary for all Husbandmen to know. (1585)
The English Huswife: Containing the Inward and Outward Virtues Which Ought to Be in a Complete Woman: as her Phisicke, Cookery, Banqueting-stuffe, Distillation, Perfumes, Wooll, Hemp, Flaxe, Dairies, Brewing, Baking, and all other things belonging to an Houshold (1615)
The closet of the eminently learned Sir Kenelm Digbie Kt. opened: Whereby is discovered several ways for making of metheglin, sider, cherry-wine &c. together with excellent directions for cookery: as also for preserving, conserving, candying, &c. (1669)
The Queen-like Closet, Or, Rich Cabinet: Stored with all manner of RARE RECEIPTS For Preserving, Candying and Cookery Very Pleasant and Beneficial to all Ingenious Persons of the FEMALE SEX (1670)
The Receipt Book of Lady Anne Blencowe, by Anne Blencowe, 1694
Mrs Mary Eales's Receipts (1718)
A Collection of Above Three Hundred Receipts in Cookery, Physick and Surgery; For the Use of all Good Wives, Tender Mothers, and Careful Nurses (1718)
The Compleat Housewife; or, Accomplish'd Gentlewoman's Companion: being a collection of upwards of six hundred of the most approved receipts, in cookery, pastry, confectionery, preserving, pickles, cakes, creams, jellies, made wines, cordials. With copper plates curiously engraven for the regular disposition or placing the various dishes or courses. And also bills of fare for every month of the year. To which is added, a collection of nearly two hundred family receipts of medicines; viz. drinks, syrups, salves, ointments, and many other things of sovereign and approved efficacy in most distempers, pains, aches, wounds, sores, etc. [...] never before made publick; fit either for private families, or such publick-spirited gentlewomen as would be beneficent to their poor neighbours. (1727)
The Art of Cookery Made Plain and Easy [...] (1747; includes preservation, distillation, beverages, precautions against pests, shipboard advice, and remedies; the title technically contains a table of contents, numbered in Roman numerals)
The Experienced English Housekeeper: for the use and ease of ladies, housekeepers, cooks, &c, wrote purely from practice [...] consisting of near nine hundred original receipts, most of which never appeared in print (1769)
The Lady's Complete Guide, or Cookery in all its Branches; Containing the most approved Receipts, confirmed by Observation and Practice, in every reputable English Book of Cookery now extant [...] the Compleat Brewer [...] the Family Physician [...] (1788)
Mrs. Beeton's Book of Household Management (1861)
Places with stillrooms that are open to the public, often with reconstructed furnishings:
Charles Dickens Museum (a terraced house once occupied by the author)
Craigside House
Kentwell Hall (in the moated house)
Tatton Hall
Tredegar House
Uppark
Warwick Castle
Notes
Rooms | Still room | Engineering | 1,938 |
40,643,165 | https://en.wikipedia.org/wiki/Veratramine | Veratramine is an alkaloid isolated from the rhizomes of Veratrum.
References
Piperidine alkaloids | Veratramine | Chemistry | 28 |
72,765,366 | https://en.wikipedia.org/wiki/Buchwaldoboletus%20xylophilus | Buchwaldoboletus xylophilus is a species of bolete fungus in the family Boletaceae native to Asia, found on wood. It has a convex brown cap, and a red-brown stipe. Its edibility is unknown.
Taxonomy and naming
Originally described by Thomas Petch in 1922 as Boletus xylophilus, it was given its current name by Ernst Both and Beatriz Ortiz-Santana in A preliminary survey of the genus Buchwaldoboletus, published in "Bulletin of the Buffalo Society of Natural Sciences" in 2011.
Description
The cap is convex, and its surface is dry to subviscid, and "minutely velvety". Its color is ferrugineous brown. Easily peeled off the mushroom, the soft brown skin is separated from the flesh by a thin gelatinous layer. The pores are small and angular, and the pore surface stains blue with injury. The stipe is red-brown, and there is a yellow mycelium at the stipe base.
Spores are ellipsoid, smooth, and measure 4.5–5.5 by 3.2–4 μm.
Distribution
Buchwaldoboletus xylophilus has been recorded across Asia throughout Malaysia, Sri Lanka, Hong Kong, and Philippines
References
External links
Boletaceae
Fungi described in 1922
Fungi of Asia
Fungus species | Buchwaldoboletus xylophilus | Biology | 288 |
10,857 | https://en.wikipedia.org/wiki/Stage%20%28stratigraphy%29 | In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.
Rock series are divided into stages, just as geological epochs are divided into ages. Stages are divided into smaller stratigraphic units called chronozones or substages, and added together into superstages.
The term faunal stage is sometimes used, referring to the fact that the same fauna (animals) are found throughout the layer (by definition).
Definition
Stages are primarily defined by a consistent set of fossils (biostratigraphy) or a consistent magnetic polarity (see paleomagnetism) in the rock. Usually one or more index fossils that are common, found worldwide, easily recognized, and limited to a single, or at most a few, stages are used to define the stage's bottom.
Thus, for example in the local North American subdivision, a paleontologist finding fragments of the trilobite Olenellus would identify the beds as being from the Waucoban Stage whereas fragments of a later trilobite such as Elrathia would identify the stage as Albertan.
Stages were important in the 19th and early 20th centuries as they were the major tool available for dating and correlating rock units prior to the development of seismology and radioactive dating in the second half of the 20th century. Microscopic analysis of the rock (petrology) is also sometimes useful in confirming that a given segment of rock is from a particular age.
Originally, faunal stages were only defined regionally. As additional stratigraphic and geochronologic tools were developed, they were defined over ever broader areas. More recently, the adjective "faunal" has been dropped as regional and global correlations of rock sequences have become relatively certain and there is less need for faunal labels to define the age of formations. A tendency developed to use European and, to a lesser extent, Asian stage names for the same time period worldwide, even though the faunas in other regions often had little in common with the stage as originally defined.
International standardization
Boundaries and names are established by the International Commission on Stratigraphy (ICS) of the International Union of Geological Sciences. As of 2008, the ICS is nearly finished with a task begun in 1974, subdividing the Phanerozoic eonothem into internationally accepted stages using two types of benchmark. For younger stages, a Global Boundary Stratotype Section and Point (GSSP), a physical outcrop clearly demonstrates the boundary. For older stages, a Global Standard Stratigraphic Age (GSSA) is an absolute date. The benchmarks will give a much greater certainty that results can be compared with confidence in the date determinations, and such results will have farther scope than any evaluation based solely on local knowledge and conditions.
In many regions local subdivisions and classification criteria are still used along with the newer internationally coordinated uniform system, but once the research establishes a more complete international system, it is expected that local systems will be abandoned.
Stages and lithostratigraphy
Stages can include many lithostratigraphic units (for example formations, beds, members, etc.) of differing rock types that were being laid down in different environments at the same time. In the same way, a lithostratigraphic unit can include a number of stages or parts of them.
See also
European land mammal age
Geologic record
Geologic time scale
North American land mammal age
Type locality (geology)
List of geochronologic names
List of Global Boundary Stratotype Sections and Points
Notes
References
Hedberg, H.D., (editor), International stratigraphic guide: A guide to stratigraphic classification, terminology, and procedure, New York, John Wiley and Sons, 1976
International Stratigraphic Chart from the International Commission on Stratigraphy
External links
The Global Boundary Stratotype Section and Point (GSSP): overview
Chart of The Global Boundary Stratotype Sections and Points (GSSP): chart
Geotime chart displaying geologic time periods compared to the fossil record, deals with chronology and classifications for laymen (not GSSPs)
Chronostratigraphy
.
Geochronology
Geologic time scales
Geology terminology
Geological units
Paleogeography
Paleobiology
Units of time | Stage (stratigraphy) | Physics,Mathematics,Biology | 915 |
27,946,490 | https://en.wikipedia.org/wiki/Laterculus | A laterculus was, in late antiquity or the early medieval period, an inscribed tile, stone or terracotta tablet used for publishing certain kinds of information in list or calendar form. The term thus came to be used for the content represented by such an inscription, most often a list, register, or table, regardless of the medium in which it was published. A list of soldiers in a Roman military unit, such as of those recruited or discharged in a given year, may be called a laterculus, an example of which is found in an inscription from Vindonissa. The equivalent Greek term is plinthos (πλίνθος; see plinth for the architectural use).
A common type of laterculus was the computus, a table that calculates the date of Easter, and so laterculus will often be equivalent to fasti. Isidore of Seville said that a calendar cycle should be called a laterculus "because it has the years put in order by rows," that is, in a table.
List of laterculi
Notable laterculi include:
Laterculus Veronensis, a list of Roman provinces from the times of the Roman emperors Diocletian and Constantine I.
Laterculus Malalianus, a late 7th-century historical exegesis of the life of Christ from the Chronica Minora in the Monumenta Germaniae Historica, drawing from the Chronographia of John Malalas and so called by Theodor Mommsen, though only a relatively small part of the text takes the form of a list (covering Roman emperors from Augustus to Justin II).
Laterculus regum Vandalorum et Alanorum, a list of Vandal kings based in Mommsen's view on diplomas or, alternatively, largely on an African version of the Chronicle of Prosper Tiro.
Laterculus regum Visigothorum, list of Visigothic kings.
Laterculus Polemii Silvii, an Imperial Roman list of emperors and provinces by Polemius Silvius.
References
Inscriptions by type
Latin inscriptions
Calendars
Medieval documents
Medieval genealogies and succession lists
Military history of ancient Rome
Terracotta
Regnal lists | Laterculus | Physics | 449 |
41,819,435 | https://en.wikipedia.org/wiki/Surface%20triangulation | Triangulation of a surface means
a net of triangles, which covers a given surface partly or totally, or
the procedure of generating the points and triangles of such a net of triangles.
Approaches
This article describes the generation of a net of triangles. In literature there are contributions which deal with the optimization of a given net.
Surface triangulations are important for
visualizing surfaces and
the application of finite element methods.
The triangulation of a parametrically defined surface is simply achieved by triangulating the area of definition (see second figure, depicting the Monkey Saddle). However, the triangles may vary in shape and extension in object space, posing a potential drawback. This can be minimized through adaptive methods that consider step width while triangulating the parameter area.
To triangulate an implicit surface (defined by one or more equations) is more difficult.
There exist essentially two methods.
One method divides the 3D region of consideration into cubes and determines the intersections of the surface with the edges of the cubes in order to get polygons on the surface, which thereafter have to be triangulated (cutting cube method). The expenditure for managing the data is great.
The second and simpler concept is the marching method. The triangulation starts with a triangulated hexagon at a starting point. This hexagon is then surrounded by new triangles, following given rules, until the surface of consideration is triangulated. If the surface consists of several components, the algorithm has to be started several times using suitable starting points.
The cutting cube algorithm determines, at the same time, all components of the surface within the surrounding starting cube depending on prescribed limit parameters. An advantage of the marching method is the possibility to prescribe boundaries (see picture).
Polygonizing a surface means to generate a polygon mesh.
The triangulation of a surface should not be confused with the triangulation of a discrete prescribed plane set of points. See Delaunay triangulation.
See also
Computer-aided design
Mesh generation
Tessellation (computer graphics)
Marching cubes
Point set triangulation
References
External links
Tasso Karkanis & A. James Stewart: Curvature-Dependent Triangulation of Implicit Surfaces
Software
Surface reconstruction tutorial and list of surface triangulation algorithms in the Point Cloud Library
Surfaces
Computer-aided design
Finite element method
Triangle geometry | Surface triangulation | Engineering | 481 |
58,505,053 | https://en.wikipedia.org/wiki/Bioinorganic%20Chemistry%20Award | The Bioinorganic Chemistry Award has been awarded by the Dalton division of the Royal Society of Chemistry every two years since 2009. The winner receives £2000 and undertakes a lecture tour in the UK. The award was discontinued in 2020.
Winners
Source:
See also
List of chemistry awards
References
Awards of the Royal Society of Chemistry
Bioinorganic chemistry | Bioinorganic Chemistry Award | Chemistry,Technology,Biology | 73 |
64,242,581 | https://en.wikipedia.org/wiki/Isolichenan | Isolichenan, also known as isolichenin, is a cold-water-soluble α-glucan occurring in certain species of lichens. This lichen product was first isolated as a component of an extract of Iceland moss in 1813, along with lichenin. After further analysis and characterization of the individual components of the extract, isolichenan was named in 1881. It is the first α-glucan to be described from lichens. The presence of isolichenan in the cell walls is a defining characteristic in several genera of the lichen family Parmeliaceae. Although most prevalent in that family, it has also been isolated from members of the families Ramalinaceae, Stereocaulaceae, Roccellaceae, and Cladoniaceae. Experimental studies have shown that isolichenan is produced only when the two lichen components – fungus and alga – are growing together, not when grown separately. The biological function of isolichenan in the lichen thallus is unknown.
Early studies
Isolichenan was first isolated from Cetraria islandica in 1813 by Swedish chemist Jöns Jacob Berzelius, who also at the same time isolated the cellulose-like hot-water-soluble glucan lichenan. Because in these experiments the isolichenan component of the lichen extract had a positive reaction with iodine staining (i.e. production of a blue colour), Berzelius thought it to be similar in nature to starch, and he called it "lichen starch". It was thought to function as a reserve food source for the organism. Later studies showed it to be a mixture of polysaccharides. In 1838, Gerardus Johannes Mulder isolated the blue-staining component of the C. islandica extract, believing it to be starch. Friedrich Konrad Beilstein gave the name "isolichenan" to this substance in 1881. Isolichenan was the first α-glucan described from lichens.
In 1947, Kurt Heinrich Meyer and P. Gürtler, discussing the preparation of lichenan, reported that the mother liquor contained a water-soluble glucan that could be purified by repeated freezing and thawing. In this process, which completely removed lichenan, they obtained isolichenan in a 0.55% yield.
Structure
Isolichenan is a polymer of glucose units joined by a mixture of α-(1→3) and α-(1→4) linkages. Using the technique of partial acid hydrolysis, Stanley Peat and colleagues determined that the linkages are of the α-configuration. The ratio of these linkages has been reported differently by various authors in the scientific literature: 11:9, 3:2, 2:1, 3:1, and 4:1. Fleming and Manners found the ratio to be 56.5:43.5 and 57:43 in two separate experiments using the Smith degradation procedure. This technique uses the successive steps of periodate oxidation, borohydride reduction, and mild acid hydrolysis; in this way, acetal linkages become hydrolysed, but glucosidic linkages are not. The distribution of linkages in isolichenan was found to be somewhat irregular, with both types occurring in groups of two or more in at least some areas. Another study suggests that isolichenan has mostly groups of one or two α-(1→3) bonds surrounded by α-(1→4) bonds. Compared with, for example, amylose (a linear α-(1→4)-linked glucan and the major component of starch), isolichenan has a relatively weak iodine-staining reaction. This weak staining intensity is thought to be a result of its preponderance of (1→3) linkages, a property that reduces the formation of the polyiodide-complex that gives the positive reaction its blue colour.
The chain length of isolichenan was estimated at 42–44 glucose units. The reported molecular weight of isolichenan also varies, from 26 kD to 2000 kD. The relatively short chain length of isolichenan may explain why it is soluble in cold water after it has been extracted from the lichen thallus. Purified isolichenan has a high positive specific rotation in water. It has been reported as high as +272, although different sources give differing values.
The term "isolichenan-type" has been used as a general term for α-D-glucans having (1→3)-(1→4) linkages in their main chain. Similar to isolichenan, the α-D-glucan known as Ci-3 consists of 1→3 and 1→4 linked α-D-glucose residues in ratio of 2:1, but with a much higher degree of polymerization and a molecular weight of about 2000 kD. It is also found in Cetraria islandica. As the discrepancies in reported values demonstrate, lichens produce isolichenan-type polysaccharides with considerable variation in linkage ratios as well as molecular weight, even within the same species.
The carbon-13 nuclear magnetic resonance spectrum of isolichenan was reported by Yokota and colleagues in 1979 and also by Gorin and Iacomini in 1984.
Occurrence
Since its discovery in Cetraria islandica, isolichenan has been isolated from many other lichen species. It is predominant in the Parmeliaceae, a large and diverse family of the class Lecanoromycetes. Parmeliaceae genera and species containing isolichenan include: Alectoria (A. sulcata, A. sarmentosa); Cetraria (Cetraria cucullata, C. islandica, C. nivaris, C. richardsonii; Evernia (E. prunastri); Letharia (L. vulpina); Neuropogon (N. aurantiaco-ater); Parmelia (P. caperata, P. cetrarioides, P. conspersa, P. hypotrypella, P. laevior, P. nikkoensis, P. saxatilis, P. tinctorum); Parmotrema (P. cetrarum, P. araucaria, P. sulcata); and Usnea (U. barbata, U. baylei, U. faciata, U. longissima, U. meridionalis, U. rubescens). A few members of the family Ramalinaceae have been shown to contain isolichenan, including Ramalina celastri, R. ecklonii, R. scopulorum, and R. usnea. In the family Stereocaulaceae, isolichenan has been isolated from S. excutum, S. japonicum, and S. sorediiferum. It is also known to occur in single species in the Roccellaceae (Roccella montagnei) and the Cladoniaceae (Pilophorus acicularis).
Uses
Although isolichenan is not nearly as constant at the genus level as lichenan, the presence of isolichenan in the cell walls is a defining character in several genera of the lichen family Parmeliaceae, including Asahinea, Cetrelia, Flavoparmelia, and Psiloparmelia. In contrast, the absence of isolichenan is a character of genus Xanthoparmelia.
Isolichenan is used as an active ingredient in cough lozenges as a component of Cetraria islandica extract.
Research
Isolichenan was shown to enhance hippocampal plasticity and behavioural performance in rats. When administered orally, isolichenan was also shown to improve memory acquisition in mice impaired by ethanol, as well as in rats in which memory impairment had been induced by beta-amyloid peptide. In more recent research, isolichenan was shown to improve cognitive function in healthy adults.
The main α-glucan synthesized by lichens of the genus Ramalina in the symbiotic state is isolichenan. A series of experiments have shown, however, that it is not produced by either individual symbiont when cultivated apart from each other. Its absence in this circumstance suggests that it may not have an importance as a structural part of the fungal cell wall; this contrasts with lichenan, where the (1→3)(1→4)-β-glucan has been shown to be involved in cell wall structure. Isolichenan is synthesized by the mycobiont only in the presence of its symbiotic partner (the green alga Trebouxia) in a special microenvironment – the lichen thallus. The triggering of this phenomenon and the biological function of isolichenan in the symbiotic relationship between fungi and algae is still unknown. In a study on the immunomodulatory effects of an aqueous Cetraria islandica extract, it was shown that the extract was able to upregulate the secretion of the cytokine interleukin 10. However, when the individual components of this extract (including lichenan, isolichenan, protolichesterinic and fumarprotocetraric acids) were tested with the same assay, isolichenan had no anti-inflammatory effects (only lichenan did).
Citations
Cited literature
Polysaccharides
Lichen products | Isolichenan | Chemistry | 1,990 |
2,028,895 | https://en.wikipedia.org/wiki/Weber%20number | The Weber number (We) is a dimensionless number in fluid mechanics that is often useful in analysing fluid flows where there is an interface between two different fluids, especially for multiphase flows with strongly curved surfaces. It is named after Moritz Weber (1871–1951). It can be thought of as a measure of the relative importance of the fluid's inertia compared to its surface tension. The quantity is useful in analyzing thin film flows and the formation of droplets and bubbles.
Mathematical expression
The Weber number may be written as:
where
is the density of the fluid (kg/m3).
is its velocity (m/s).
is its characteristic length, typically the droplet diameter (m).
is the surface tension (N/m).
is the inertial or dynamic pressure scale.
is the Laplace pressure scale.
The above is the force perspective to define the Weber number. We can also define it using energy perspective as the ratio of the kinetic energy on impact to the surface energy,
,
where
and
.
Appearance in the Navier-Stokes equations
The Weber number appears in the incompressible Navier-Stokes equations through a free surface boundary condition.
For a fluid of constant density and dynamic viscosity , at the free surface interface there is a balance between the normal stress and the curvature force associated with the surface tension:
Where is the unit normal vector to the surface, is the Cauchy stress tensor, and is the divergence operator. The Cauchy stress tensor for an incompressible fluid takes the form:
Introducing the dynamic pressure and, assuming high Reynolds number flow, it is possible to nondimensionalize the variables with the scalings:
The free surface boundary condition in nondimensionalized variables is then:
Where is the Froude number, is the Reynolds number, and is the Weber number. The influence of the Weber number can then be quantified relative to gravitational and viscous forces.
Applications
One application of the Weber number is the study of heat pipes. When the momentum flux in the vapor core of the heat pipe is high, there is a possibility that the shear stress exerted on the liquid in the wick can be large enough to entrain droplets into the vapor flow. The Weber number is the dimensionless parameter that determines the onset of this phenomenon called the entrainment limit (Weber number greater than or equal to 1). In this case the Weber number is defined as the ratio of the momentum in the vapor layer divided by the surface tension force restraining the liquid, where the characteristic length is the surface pore size.
References
Further reading
Weast, R. Lide, D. Astle, M. Beyer, W. (1989–1990). CRC Handbook of Chemistry and Physics. 70th ed. Boca Raton, Florida: CRC Press, Inc.. F-373,376.
Fluid dynamics
Dimensionless numbers of fluid mechanics | Weber number | Chemistry,Engineering | 601 |
3,138,467 | https://en.wikipedia.org/wiki/N-player%20game | In game theory, an n-player game is a game which is well defined for any number of players. This is usually used in contrast to standard 2-player games that are only specified for two players. In defining n-player games, game theorists usually provide a definition that allow for any (finite) number of players. The limiting case of is the subject of mean field game theory.
Changing games from 2-player games to n-player games entails some concerns. For instance, the Prisoner's dilemma is a 2-player game. One might define an n-player Prisoner's Dilemma where a single defection results everyone else getting the sucker's payoff. Alternatively, it might take certain amount of defection before the cooperators receive the sucker's payoff. (One example of an n-player Prisoner's Dilemma is the Diner's dilemma.)
Analysis
n-player games can not be solved using minimax, the theorem that is the basis of tree searching for 2-player games. Other algorithms, like maxn, are required for traversing the game tree to optimize the score for a specific player.
References
Game theory game classes | N-player game | Mathematics | 241 |
200,161 | https://en.wikipedia.org/wiki/Stream%20gauge | A stream gauge, streamgage or stream gauging station is a location used by hydrologists or environmental scientists to monitor and test terrestrial bodies of water. Hydrometric measurements of water level surface elevation ("stage") and/or volumetric discharge (flow) are generally taken and observations of biota and water quality may also be made. The locations of gauging stations are often found on topographical maps. Some gauging stations are highly automated and may include telemetry capability transmitted to a central data logging facility.
Measurement equipment
Automated direct measurement of stream discharge is difficult at present. Mathematically, measuring stream discharge is estimating the volumetric flow rate, which is in general a flux integral and thus requires many cross-sectional velocity measurements. In place of the direct measurement of stream discharge, one or more surrogate measurements can be used as proxy variables to produce discharge values. In the majority of cases, a stage (the elevation of the water surface) measurement is used as the surrogate. Low gradient (or shallow-sloped) streams are highly influenced by variable downstream channel conditions. For these streams, a second stream gauge would be installed, and the slope of the water surface would be calculated between the gauges. This value would be used along with the stage measurement to more accurately determine the streamflow discharge. Improvements in the accuracy of velocity sensors have also allowed the use of water velocity as a reliable surrogate for streamflow discharge at sites with a stable cross-sectional area. These sensors are permanently mounted in the stream and measure velocity at a particular location in the stream.
In those instances where only a stage measurement is used as the surrogate, a rating curve must be constructed. A rating curve is the functional relation between stage and discharge. It is determined by making repeated discrete measurements of streamflow discharge using a velocimeter and some means to measure the channel geometry to determine the cross-sectional area of the channel. The technicians and hydrologists responsible for determining the rating curve visit the site routinely, with special trips to measure the hydrologic extremes (floods and droughts), and make a discharge measurement by following an explicit set of instructions or standard operating procedures (SOPs).
Once the rating curve is established, it can be used in conjunction with stage measurements to determine the volumetric streamflow discharge. This record then serves as an assessment of the volume of water that passes by the stream gauge and is useful for many tasks associated with hydrology.
In those instances where a velocity measurement is additionally used as a surrogate, an index velocity determination is conducted. This analysis uses a velocity sensor, often either magnetic or acoustic, to measure the velocity of the flow at a particular location in the stream cross section. Once again, discrete measurements of streamflow discharge are made by the technician or hydrologist at a variety of stages. For each discrete determination of streamflow discharge, the mean velocity of the cross section is determined by dividing streamflow discharge by the cross-sectional area. A rating curve, similar to that used for stage-discharge determinations, is constructed using the mean velocity and the index velocity from the permanently mounted meter. An additional rating curve is constructed that relates stage of the stream to cross-sectional area. Using these two ratings, the automatically collected stage produces an estimate of the cross-sectional area, and the automatically collected index velocity produces an estimate of the mean velocity of the cross section. The streamflow discharge is computed as the product of the estimate of the cross section area and the estimate of the mean velocity of the streamflow.
A variety of hydraulic structures / primary device are used to improve the reliability of using water level as a surrogate for flow (improving the accuracy of the rating table), including:
Weirs
V-notch,
broad-crested,
sharp-crested and
combination weirs
Flumes
Parshall flume
Other equipment commonly used at permanent stream gauge include:
Cableways - for suspending a hydrographer and current meter over a river to make high flow measurement
Stilling well - to provide a calm water level that can be measured by a sensor
Water level gauges:
Staff (head) gauges - for a visual indication of water depth
Water pressure measuring device (Bubbler) - to measure water level via pressure (typically done directly in-stream without a stilling well)
Stage encoder - a potentiometer with a wheel and pulley system connected to a float in a stilling well to provide an electronic reading of the water level
Simple ultrasonic devices - to measure water level in a stilling well or directly in a canal.
Electromagnetic gauges
Discharge measurements of a stream or canal without an established stream gauge can be made using a current meter or Acoustic Doppler current profiler. One informal methods that is not acceptable for any official or scientific purpose, but can be useful is the float method, in which a floating object such as a piece of wood or orange peel is observed floating down the stream.
National stream gauge networks
United Kingdom
The first routine measurements of river flow in England began on the Thames and Lea in the 1880s, and in Scotland on the River Garry in 1913. The national gauging station network was established in its current form by the early 1970s and consists of approximately 1500 flow measurement stations supplemented by a variable number of temporary monitoring sites. The Environment Agency is responsible for collection and analysis of hydrometric data in England, Natural Resources Wales in Wales, whilst responsibility for Scotland and Northern Ireland rests with the Scottish Environment Protection Agency and Rivers Agency respectively.
United States
In the United States, the U.S. Geological Survey (USGS) is the principal federal agency tasked with maintaining records of natural resources. Within the USGS, the Water Resources Division carries the responsibility for monitoring water resources.
To establish a stream gauge, USGS personnel first choose a site on a stream where the geometry is relatively stable and there is a suitable location to make discrete direct measurements of streamflow using specialized equipment. Many times this will be at a bridge or other stream crossing. Technicians then install equipment that measures the stage (the elevation of the water surface) or, more rarely, the velocity of the flow. Additional equipment is installed to record and transmit these readings (via the Geostationary Operational Environmental Satellite) to the Water Science Center office where the records are kept. The USGS has a Water Science Center office in every state within the United States. Current streamflow data from USGS streamgages may be viewed in map form at: .
Zimbabwe
In Zimbabwe, the national stream gauge network is the responsibility of the Zimbabwe National Water Authority. This is an extensive network covering all major rivers and catchments in the country. However, a review of existing gauges raised serious concerns about the reliability of the data of a minority of stations, due in part to ongoing funding problems.
Bangladesh
The largest stream gauge network in Bangladesh is maintained by Bangladesh Water Development Board (BWDB). At few other locations, Bangladesh Inland Water Transport Authority maintains a few gauges to provide advisories for navigational purposes.
Czech Republic
In the Czech Republic, in some measuring places (profiles) are defined three levels which define three degrees of flood-emergency activity. The degree I is a situation of alertness, the degree II is a situation of readiness, the degree III is a situation of danger.
Canada
Canadian streams and rivers are monitored by the Water Survey of Canada, a branch of Environment and Climate Change Canada. As of 2021, it operates or collects data from more than 2800 gauges across Canada. This data is used by provincial and territory governments to inform flood predictions and water management.
Sri Lanka
In Sri Lanka stream and rivers are monitored by Hydrology and Disaster Management Division a branch of Irrigation Department. It operates nearly 40 gauging station around the island.
See also
Willow Beach Gauging Station
References
Further reading
World Meteorological Organization (2010) Manual on Stream Gauging.
Volume I - Fieldwork.
Volume II - Computation of Discharge.
External links
Contoocook River Streamflow-Gaging Station, Water Resources of New Hampshire and Vermont
"USGS Surface-Water Data for the Nation"
UK Hydrometric Register (pdf) A catalogue of river flow gauging stations and observation wells and boreholes in the United Kingdom together with summary hydrometric and spatial statistics.
"Radio Gauge Warns of Flood as Water Rises" Popular Mechanics, July 1935
Hydrology instrumentation | Stream gauge | Technology,Engineering,Environmental_science | 1,695 |
2,674,674 | https://en.wikipedia.org/wiki/List%20of%20compounds%20with%20carbon%20numbers%2030%E2%80%9339 | This is a partial list of molecules that contain 30 to 39 carbon atoms.
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
See also
Carbon number
References
C30 | List of compounds with carbon numbers 30–39 | Chemistry | 44 |
23,706 | https://en.wikipedia.org/wiki/Primitive%20notion | In mathematics, logic, philosophy, and formal systems, a primitive notion is a concept that is not defined in terms of previously-defined concepts. It is often motivated informally, usually by an appeal to intuition or taken to be self-evident. In an axiomatic theory, relations between primitive notions are restricted by axioms. Some authors refer to the latter as "defining" primitive notions by one or more axioms, but this can be misleading. Formal theories cannot dispense with primitive notions, under pain of infinite regress (per the regress problem).
For example, in contemporary geometry, point, line, and contains are some primitive notions. Instead of attempting to define them, their interplay is ruled (in Hilbert's axiom system) by axioms like "For every two points there exists a line that contains them both".
Details
Alfred Tarski explained the role of primitive notions as follows:
When we set out to construct a given discipline, we distinguish, first of all, a certain small group of expressions of this discipline that seem to us to be immediately understandable; the expressions in this group we call PRIMITIVE TERMS or UNDEFINED TERMS, and we employ them without explaining their meanings. At the same time we adopt the principle: not to employ any of the other expressions of the discipline under consideration, unless its meaning has first been determined with the help of primitive terms and of such expressions of the discipline whose meanings have been explained previously. The sentence which determines the meaning of a term in this way is called a DEFINITION,...
An inevitable regress to primitive notions in the theory of knowledge was explained by Gilbert de B. Robinson:
To a non-mathematician it often comes as a surprise that it is impossible to define explicitly all the terms which are used. This is not a superficial problem but lies at the root of all knowledge; it is necessary to begin somewhere, and to make progress one must clearly state those elements and relations which are undefined and those properties which are taken for granted.
Examples
The necessity for primitive notions is illustrated in several axiomatic foundations in mathematics:
Set theory: The concept of the set is an example of a primitive notion. As Mary Tiles writes: [The] 'definition' of 'set' is less a definition than an attempt at explication of something which is being given the status of a primitive, undefined, term. As evidence, she quotes Felix Hausdorff: "A set is formed by the grouping together of single objects into a whole. A set is a plurality thought of as a unit."
Naive set theory: The empty set is a primitive notion. To assert that it exists would be an implicit axiom.
Peano arithmetic: The successor function and the number zero are primitive notions. Since Peano arithmetic is useful in regards to properties of the numbers, the objects that the primitive notions represent may not strictly matter.
Arithmetic of real numbers: Typically, primitive notions are: real number, two binary operations: addition and multiplication, numbers 0 and 1, ordering <.
Axiomatic systems: The primitive notions will depend upon the set of axioms chosen for the system. Alessandro Padoa discussed this selection at the International Congress of Philosophy in Paris in 1900. The notions themselves may not necessarily need to be stated; Susan Haack (1978) writes, "A set of axioms is sometimes said to give an implicit definition of its primitive terms."
Euclidean geometry: Under Hilbert's axiom system the primitive notions are point, line, plane, congruence, betweeness, and incidence.
Euclidean geometry: Under Peano's axiom system the primitive notions are point, segment, and motion.
Russell's primitives
In his book on philosophy of mathematics, The Principles of Mathematics Bertrand Russell used the following notions: for class-calculus (set theory), he used relations, taking set membership as a primitive notion. To establish sets, he also establishes propositional functions as primitive, as well as the phrase "such that" as used in set builder notation. (pp 18,9) Regarding relations, Russell takes as primitive notions the converse relation and complementary relation of a given xRy. Furthermore, logical products of relations and relative products of relations are primitive. (p 25) As for denotation of objects by description, Russell acknowledges that a primitive notion is involved. (p 27) The thesis of Russell’s book is "Pure mathematics uses only a few notions, and these are logical constants." (p xxi)
See also
Axiomatic set theory
Foundations of geometry
Foundations of mathematics
Logical atomism
Logical constant
Mathematical logic
Notion (philosophy)
Natural semantic metalanguage
References
Philosophy of logic
Set theory
Concepts in logic
Mathematical concepts | Primitive notion | Mathematics | 959 |
13,277,538 | https://en.wikipedia.org/wiki/Thermal%20conductivity%20detector | The thermal conductivity detector (TCD), also known as a katharometer, is a bulk property detector and a chemical specific detector commonly used in gas chromatography. This detector senses changes in the thermal conductivity of the column eluent and compares it to a reference flow of carrier gas. Since most compounds have a thermal conductivity much less than that of the common carrier gases of helium or hydrogen, when an analyte elutes from the column the effluent thermal conductivity is reduced, and a detectable signal is produced.
Operation
The TCD consists of an electrically heated filament in a temperature-controlled cell. Under normal conditions there is a stable heat flow from the filament to the detector body. When an analyte elutes and the thermal conductivity of the column effluent is reduced, the filament heats up and changes resistance. This resistance change is often sensed by a Wheatstone bridge circuit which produces a measurable voltage change. The column effluent flows over one of the resistors while the reference flow is over a second resistor in the four-resistor circuit.
A schematic of a classic thermal conductivity detector design utilizing a Wheatstone bridge circuit is shown. The reference flow across resistor 4 of the circuit compensates for drift due to flow or temperature fluctuations. Changes in the thermal conductivity of the column effluent flow across resistor 3 will result in a temperature change of the resistor and therefore a resistance change which can be measured as a signal.
Since all compounds, organic and inorganic, have a thermal conductivity different from helium or hydrogen, virtually all compounds can be detected. That's why the TCD is often called a universal detector.
Used after a separation column (in a chromatograph), a TCD measures the concentrations of each compound contained in the sample. Indeed, the TCD signal changes when a compound passes through it, shaping a peak on a baseline. The peak position on the baseline reflects the compound type. The peak area (computed by integrating the TCD signal over time) is representative of the compound concentration. A sample whose compounds concentrations are known is used to calibrate the TCD: concentrations are affected to peak areas through a calibration curve.
The TCD is a good general purpose detector for initial investigations with an unknown sample compared to the FID that will react only to combustible compounds (Ex: hydrocarbons). Moreover, the TCD is a non-specific and non-destructive technique. The TCD is also used in the analysis of permanent gases (argon, oxygen, nitrogen, carbon dioxide) because it responds to all these substances unlike the FID which cannot detect compounds which do not contain carbon-hydrogen bonds.
Considering detection limit, both TCD and FID reach low concentration levels (inferior to ppm or ppb).
Both of them require pressurized carrier gas (Typically: H2 for FID, He for TCD) but due to the risk associated with storing H2 (high flammability, see Hydrogen safety), TCD with He should be considered in locations where safety is crucial.
Considerations
One thing to be aware of when operating a TCD is that gas flow must never be interrupted when the filament is hot, as doing so may cause the filament to burn out. While the filament of a TCD is generally chemically passivated to prevent it from reacting with oxygen, the passivation layer can be attacked by halogenated compounds, so these should be avoided wherever possible.
If analyzing for hydrogen, the peak will appear as negative when helium is used as the reference gas. This problem can be avoided if another reference gas is used, for example argon or nitrogen, although this will significantly reduce the detector's sensitivity towards any compounds other than hydrogen.
Process description
It functions by having two parallel tubes both containing gas and heating coils. The gases are examined by comparing the rate of loss of heat from the heating coils into the gas. The coils are arranged in a bridge circuit so that resistance changes due to unequal cooling can be measured. One channel normally holds a reference gas and the mixture to be tested is passed through the other channel.
Applications
Katharometers are used medically in lung function testing equipment and in gas chromatography. The results are slower to obtain compared to a mass spectrometer, but the device is inexpensive, and has good accuracy when the gases in question are known, and it is only the proportion that must be determined.
Monitoring of hydrogen purity in hydrogen-cooled turbogenerators.
Detection of helium loss from the helium vessel of an MRI superconducting magnet.
Also used within the brewing industry to quantify the amount of carbon dioxide within beer samples.
Used within the energy industry to quantify the amount (calorific value) of methane within biogas samples.
Used within the food and drink industry to quantify and/or validate food packaging gases.
Used within the oil&gas industry to quantify the percentage of HCs when drilling into a formation.
References
Gas chromatography
Measuring instruments | Thermal conductivity detector | Chemistry,Technology,Engineering | 1,060 |
2,743,934 | https://en.wikipedia.org/wiki/Omicron%20Virginis | Omicron Virginis (ο Vir, ο Virginis) is a star in the zodiac constellation of Virgo. It is visible to the naked eye with an apparent visual magnitude of +4.12. Based upon parallax measurements, it is about 163 light years from the Sun.
ο Virginis is a G-type giant star with a stellar classification of G8 IIIa CN-1Ba1CH1. This indicates that it is a Barium star. Typically Barium stars are close binaries with a white dwarf companion, but no companion has been detected for ο Virginis. It has been suggested that an excess SiIV emission flux is due to an unseen white dwarf companion.
ο Virginis is a giant star around ten times larger than the Sun. Although it is slightly cooler, it is radiating about 60-132 times the luminosity of the Sun. It is over twice as massive as the Sun and is around a billion years old. A simplified statistical analysis suggests that ο Virginis is likely to be a red giant branch star fusing hydrogen in a shell around an inert helium core, but there is about a 22% chance that it is a horizontal branch star fusing helium in its core.
References
G-type giants
Barium stars
Virginis, Omicron
Virgo (constellation)
BD+09 2583
Virginis, 009
3703
104979
058948
4608 | Omicron Virginis | Astronomy | 292 |
41,481 | https://en.wikipedia.org/wiki/Packet-switching%20node | A packet-switching node is a node in a packet-switching network that contains data switches and equipment for controlling, formatting, transmitting, routing, and receiving data packets.
Note: In the Defense Data Network (DDN), a packet-switching node is usually configured to support up to thirty-two X.25 56 kbit/s host connections, as many as six 56 kbit/s interswitch trunk (IST) lines to other packet-switching nodes, and at least one Terminal Access Controller (TAC).
Packets (information technology) | Packet-switching node | Technology | 116 |
48,582,546 | https://en.wikipedia.org/wiki/Trimble%20ASCII%20Interface%20Protocol | The Trimble ASCII Interface Protocol is a digital communication interface which uses printable ASCII characters over a serial link. It is used to communicate with Global Positioning System receivers.
See also
NMEA 0183
NMEA 2000
References
Interfaces
Logical communication interfaces
Serial digital interface
Digital communication interfaces | Trimble ASCII Interface Protocol | Technology | 60 |
21,931,701 | https://en.wikipedia.org/wiki/Ecclesiastical%20full%20moon | An ecclesiastical full moon is formally the 14th day of the ecclesiastical lunar month (an ecclesiastical moon) in an ecclesiastical lunar calendar. The ecclesiastical lunar calendar spans the year with lunar months of 30 and 29 days which are intended to approximate the observed phases of the Moon. Since a true synodic month has a length that can vary from about 29.27 to 29.83 days, the moment of astronomical opposition tends to be roughly 14.75 days after the previous conjunction of the Sun and Moon (the new moon). The ecclesiastical full moons of the Gregorian lunar calendar tend to agree with the dates of astronomical opposition, referred to a day beginning at midnight at 0 degrees longitude, to within a day or so. However, the astronomical opposition happens at a single moment for the entire Earth: The hour and day at which the opposition is measured as having taken place will vary with longitude. In the ecclesiastical calendar, the 14th day of the lunar month, reckoned in local time, is considered the day of the full moon at each longitude.
Schematic lunar calendars can and do get out of step with the Moon. A useful way of checking their performance is to compare the variation of the astronomical new moon with a standard time of 6 a.m. on the last day of a 30-day month and 6 p.m. (end of day) on the last day of a 29-day month.
Beginning in the medieval period the age of the ecclesiastical moon was announced daily in the office of Prime at the reading of the martyrology. This is still done today by those using the extraordinary form of the Roman Rite adhering to the 1962 Roman Breviary.
In the Book of Common Prayer of the Protestant Episcopal Church of the United States of America, the dates of the paschal full moons for the 19 years of the Gregorian Easter cycle are indicated by the placement of the Golden Number to the left of the date in March or April on which the paschal full moon falls in that year of the cycle. The same practice is followed in some editions of the Book of Common Prayer of the Church of England.
Paschal full moon
The paschal full moon is the ecclesiastical full moon of the northern spring and is used in the determination of the date of Easter. The name "paschal" is derived from "Pascha", a transliteration of the Aramaic word meaning Passover. The date of Easter is determined as the first Sunday after the "paschal full moon" that falls on or after March 21. (March 21 is the ecclesiastical equinox, the date fixed by the Gregorian reform of the calendar as a fixed reference date for the Spring Equinox in the Northern hemisphere; the actual Equinox can fall on March 19, 20 or 21). This "full moon" does not currently correspond directly to any astronomical event, but is instead the 14th day of a lunar month, determined from tables. It may differ from the date of the actual full moon by up to two days.
The calculations to determine the date of the paschal full moon can be described as follows:
Nineteen civil calendar years are divided into 235 lunar months of 30 and 29 days each.
This period of 19 years (the metonic cycle) is used because it produces a set of civil calendar dates for the ecclesiastical moons that repeats every nineteen years while still providing a reasonable approximation to the astronomical facts.
The first day of each of these lunar months is the ecclesiastical new moon. Exactly one ecclesiastical new moon in each year falls on a date between March 8 and April 5, both inclusive. This begins the paschal lunar month for that year, and thirteen days later (that is, between March 21 and April 18, both inclusive) is the paschal full moon.
Easter is the Sunday following the paschal full moon.
In other words, Easter falls from one to seven days after the paschal full moon, so that if the paschal full moon is on Sunday, Easter is the following Sunday. Thus the earliest possible date of Easter is March 22, while the latest possible date is April 25.
Earliest Easter
In 1818, as a paschal full moon fell on Saturday March 21 (the ecclesiastical fixed date for the Equinox), Easter was the following day—Sunday March 22—the earliest date possible. It will not fall on this date again until 2285, a span of 467 years.
Latest Easter
In 1943 a full moon fell on Saturday March 20. As this was before March 21, the next full moon, which fell on Sunday April 18, determined the date of Easter—the following Sunday, April 25. It will not fall on this date again until 2038, a span of 95 years.
For a detailed discussion of the paschal computations, see Date of Easter (the Computus).
Easter tables
By the middle of the third century AD computists of some churches, among which were the Church of Rome and the one of Alexandria, had begun to calculate their own periodic sequences of dates of paschal full moon, to be able to determine their own dates of Easter Sunday. The motivation for these experiments was a dissatisfaction with the Jewish calendars that Christians had hitherto relied on to fix the date of Easter. These Jewish calendars, according to their Christian critics, sometimes placed Nisan 14, the paschal full moon and the day of preparation for the Jewish Passover, before the spring equinox (see Easter). The Christians who began the experiments with independent computations held that the paschal full moon should never precede the equinox.
The computational principles developed at Alexandria eventually became normative, but their reception was a centuries-long process during which Alexandrian Easter tables competed with other tables incorporating different arithmetical parameters. So for a period of several centuries the sequences of dates of the paschal full moon applied by different churches could show great differences (see Easter controversy).
See also
Computus
Dionysius Exiguus' Easter table
Golden numbers
Reform of the date of Easter
References
Calendars
Catholic liturgy
Christian terminology
Date of Easter
Eastern Christian liturgy
Full moon | Ecclesiastical full moon | Physics | 1,230 |
3,283,594 | https://en.wikipedia.org/wiki/INTERBUS | INTERBUS is a serial bus system which transmits data between control systems (e.g., PCs, PLCs, VMEbus computers, robot controllers etc.) and spatially distributed I/O modules that are connected to sensors and actuators (e.g., temperature sensors, position switches).
The INTERBUS system was developed by Phoenix Contact and has been available since 1987. It is one of the leading Fieldbus systems in the automation industry and is fully standardized according to European Standard EN 50254 and IEC 61158.
At the moment, more than 600 manufacturers are involved in the implementation of INTERBUS technology in control systems and field devices.
Since 2011 the INTERBUS technology is hosted by the industry association Profibus and Profinet International.
See also
BiSS interface
External links
www.interbusclub.com
www.phoenixcontact.com
Explanation of Bit-based Sensor networks including SeriPlex
Serial buses
Industrial computing
Industrial automation | INTERBUS | Technology,Engineering | 200 |
565,214 | https://en.wikipedia.org/wiki/7000%20%28number%29 | 7000 (seven thousand) is the natural number following 6999 and preceding 7001.
Selected numbers in the range 7001–7999
7001 to 7099
7021 – triangular number
7043 – Sophie Germain prime
7056 = 842
7057 – cuban prime of the form x = y + 1, super-prime
7073 – Leyland number
7079 – Sophie Germain prime, safe prime
7100 to 7199
7103 – Sophie Germain prime, sexy prime with 7109
7106 – octahedral number
7109 – super-prime, sexy prime with 7103
7121 – Sophie Germain prime
7140 – triangular number, also a pronic number and hence = 3570 is also a triangular number, tetrahedral number
7141 - sum of the first 58 primes, star number
7151 – Sophie Germain prime
7155 – number of 19-bead necklaces (turning over is allowed) where complements are equivalent
7187 – safe prime
7192 – weird number
7193 – Sophie Germain prime, super-prime
7200 to 7299
7200 – pentagonal pyramidal number
7211 – Sophie Germain prime
7225 = 852, centered octagonal number
7230 = 362 + 372 + 382 + 392 + 402 = 412 + 422 + 432 + 442
7246 – centered heptagonal number
7247 – safe prime
7260 – triangular number
7267 – decagonal number
7272 – Kaprekar number
7283 – super-prime
7291 – nonagonal number
7300 to 7399
7310 - pronic number
7316 – number of 18-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed
7338 – Fine number.
7349 – Sophie Germain prime
7351 – super-prime, cuban prime of the form x = y + 1
7381 – triangular number
7385 – Keith number
7396 = 862
7400 to 7499
7417 – super-prime
7418 - sum of the first 59 primes
7433 – Sophie Germain prime
7471 – centered cube number
7481 – super-prime, cousin prime
7482 - pronic number
7500 to 7599
7503 – triangular number
7523 – balanced prime, safe prime, super-prime
7537 – prime of the form 2p-1
7541 – Sophie Germain prime
7559 – safe prime
7560 – the 20th highly composite number
7561 – Markov prime, star prime
7568 – centered heptagonal number
7569 = 872, centered octagonal number
7583 – balanced prime
7600 to 7699
7607 – safe prime, super-prime
7612 – decagonal number
7614 – nonagonal number
7626 – triangular number
7643 – Sophie Germain prime, safe prime
7647 – Keith number
7649 – Sophie Germain prime, super-prime
7656 - pronic number
7691 – Sophie Germain prime
7699 – super-prime, emirp, sum of the first 60 primes, first prime above 281 to be the sum of the first k primes for some k
7700 to 7799
7703 – safe prime
7710 = number of primitive polynomials of degree 17 over GF(2)
7714 – square pyramidal number
7727 – safe prime
7739 – member of the Padovan sequence
7741 = number of trees with 15 unlabeled nodes
7744 = 882, square palindrome not ending in 0
7750 – triangular number
7753 – super-prime
7770 – tetrahedral number
7776 = 65, number of primitive polynomials of degree 18 over GF(2)
7777 – Kaprekar number, repdigit
7800 to 7899
7810 – ISO/IEC 7810 is the ISO's standard for physical characteristics of identification cards
7821 – n=6 value of
7823 – Sophie Germain prime, safe prime, balanced prime
7825 – magic constant of n × n normal magic square and n-Queens Problem for n = 25. Also the first counterexample in the Boolean Pythagorean triples problem.
7832 - pronic number
7841 – Sophie Germain prime, balanced prime, super-prime
7875 – triangular number
7883 – Sophie Germain prime, super-prime
7897 – centered heptagonal number
7900 to 7999
7901 – Sophie Germain prime
7909 – Keith number
7912 – weird number
7919 – 1000th prime number
7920 – the order of the Mathieu group M11, the smallest sporadic simple group
7921 = 892, centered octagonal number
7944 – nonagonal number
7957 – super-Poulet number
7965 – decagonal number
7979 – highly cototient number
7982 - sum of the first 61 primes
7993 - star prime, reverse superstar prime
Prime numbers
There are 107 prime numbers between 7000 and 8000:
7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103, 7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213, 7219, 7229, 7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331, 7333, 7349, 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477, 7481, 7487, 7489, 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549, 7559, 7561, 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643, 7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717, 7723, 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829, 7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919, 7927, 7933, 7937, 7949, 7951, 7963, 7993
References
Integers | 7000 (number) | Mathematics | 1,398 |
62,781,020 | https://en.wikipedia.org/wiki/NearlyFreeSpeech | NearlyFreeSpeech is a privately funded, US-based, low cost web hosting provider and domain name registrar that began in 2002. It was started in response to concerns about the entry of large companies into Internet publishing, and to promote freedom of speech.
History
In September 2006, Jeffrey D. Wheelhouse registered the NearlyFreeSpeech trademark.
Endorsements
By 2008, Michael Hemmingson of San Diego Reader wrote that the Electronic Frontier Foundation suggested using services such as NearlyFreeSpeech.net and Tor software to avoid being fired for blogging. In 2009 Shawn Powers of Linux Journal reviewed Nearly Free Speech and recommended them over GoDaddy even after having some technical issues. In 2010 Jason Fitzpatrick of LifeHacker.com listed Nearly Free Speech as first of "Five Best Personal Web Hosts" and said they were unusual because of their incremental billing based on usage. In a similar 2012 "top five" list by Alan Henry of LifeHacker.com, Nearly Free Speech was given "honorable mention" and he said they offer exceptional hosting plans for as low as $0.25, and promise to only make you pay for what you use.
In 2010 in "Twitter Application Development For Dummies", Dusty Reagan recommended Nearly Free Speech for learning PHP development. In 2010 Cody Fink of MacStories.net, describing how to install Fever in 10 minutes, called Nearly Free Speech, "an amazing hosting solution that's relatively cheap, especially for light use." In 2012 in "Handbook of Research on Didactic Strategies and Technologies for Education" Nearly Free Speech was cited as a "pay as you go" service, which could reduce costs significantly. In 2013, Nearly Free Speech was used for a low-cost promotion involving the posting of indie Zelda-alike game Anodyne on The Pirate Bay.
Controversies
BugMeNot controversy
In 2004 Matt Hines of CNET said Nearly Free Speech supported BugMeNot against take-down attempts. Kevin Newcomb of clickz.com wrote that Texas-based NearlyFreeSpeech.net spokesman Jeff Wheelhouse said, "NearlyFreeSpeech.NET supports and defends the free expression rights of www.bugmenot.com and all our members to the very limit of its terms of service."
BugMeNot's move to the Nearly Free Speech provider, which also hosts a number of highly controversial sites, prompted BugMeNot's creator to say, "Personally, I don't care if I'm sharing a server with neo-Nazis. I might not agree with what they have to say, but the whole thing about freedom of speech is that people are free to speak."
Badger Killers website controversy
In 2012, Kelly Fiveash of The Register said US-based hosting firm Nearly Free Speech resisted UK government attempts to take down the Badger-Killers website, which had personal details of persons deemed to be badger cull supporters, including politicians, farmers and professors.
Alt-right and other controversies
In 2017, Ali Breland of theHill.com described how NearlyFreeSpeech's commitment was tested in the 2012 badger culling website case. She also quoted the CEO of alt-right Twitter alternative Gab, who said that NearlyFreeSpeech might be a "safe haven" for his website after their web host gave them five days to transfer their domain. In 2017 in Media Law, Ethics, and Policy in the Digital Age, NearlyFreeSpeech's policy of not shutting down site services without a court order made them the hosting choice for Crocels News after other services shutdown their services during a defamation dispute. In 2019 in Technical Blogging: Amplify Your Influence, Antonio Cangiano "wholeheartedly" recommended Nearly Free Speech as registrar and webhost for controversial content.
In January 2021, NearlyFreeSpeech published a statement on their response to a surge in business and communications from "racists." The statement was intended to clarify their positions on "free speech," refusal to host illegal content, careful cooperation with law enforcement, and opposition of racism, hatred and bigotry.
References
External links
Employee-owned companies of the United States
Web hosting
File hosting
Domain name registrars
Cloud platforms
Internet properties established in 2002 | NearlyFreeSpeech | Technology | 866 |
2,910,720 | https://en.wikipedia.org/wiki/Casing%20%28borehole%29 | Casing is a large diameter pipe that is assembled and inserted into a recently drilled section of a borehole. Similar to the bones of a spine protecting the spinal cord, casing is set inside the drilled borehole to protect and support the wellstream. The lower portion (and sometimes the entirety) is typically held in place with cement. Deeper strings usually are not cemented all the way to the surface, so the weight of the pipe must be partially supported by a casing hanger in the wellhead.
Casing that is cemented in place aids the drilling process in several ways:
Prevents contamination of fresh water well zones.
Prevents unstable upper formations from caving in and sticking the drill string or forming large caverns.
Provides a strong upper foundation to allow use of high-density drilling fluid to continue drilling deeper.
Isolates various zones, which may have different pressures or fluids, in the drilled formations from one another.
Seals off high pressure zones from the surface, minimizing potential for a blowout.
Prevents fluid loss into or contamination of production zones.
Provides a smooth internal bore for installing production equipment.
Optimum design of the casing program decreases the well construction costs, enhances the efficiency of operations and also diminishes the environmental impacts.
A slightly different metal string, called production tubing, is often used without cement inside the final casing string of a well to contain production fluids and convey them to the surface from an underground reservoir.
Design
In the planning stages of a well, a drilling engineer, usually with input from geologists and others, will pick strategic depths at which the hole will need to be cased in order for drilling to reach the desired total depth. This decision is often based on subsurface data such as formation pressures and strengths, well integrity, and is balanced against the cost objectives and desired drilling strategy.
With the casing set depths determined, hole sizes and casing sizes must follow. The hole drilled for each casing string must be large enough to accommodate the casing to be placed inside it, allowing room for cement between the outside of that casing and the hole. Also, subsequent bits that will continue drilling obviously must pass through existing casing strings. Thus, each casing string will have a subsequently smaller diameter. The inside diameter of the final casing string (or penultimate one in some instances of a liner completion) must accommodate the production tubing and associated hardware such as packers, gas lift mandrels and subsurface safety valves.
Casing design for each size of designed pipes is done by calculating the worst conditions that may be faced during drilling and over the producing life of the well. Mechanical properties such as longitudinal tensile strength, and burst and collapse resistance (calculated considering biaxial effects of axial and hoop stresses), must be sufficient at various depths. Pipe of differing strengths often comprises a long casing string, which typically will have the greatest axial tension and perhaps highest internal burst pressure differentials in the upper parts, and the greatest collapsing loads deeper in the well from external pressure vs lowered internal pressure.
Casing strings are supported by casing hangers that are set in the wellhead, which later will be topped with the Christmas tree. The lower members of the wellhead usually are installed on top of the first casing string after it has been cemented in place.
Intervals
Typically, a well contains multiple intervals of casing successively placed within the previous casing run. The following casing intervals are typically used in an oil or gas well:
Conductor casing
Surface casing
Intermediate casing (optional)
Production casing
Production liner
The conductor casing serves as a support during drilling operations, to flowback returns during drilling and cementing of the surface casing, and to prevent collapse of the loose soil near the surface. It can normally vary from sizes such as .
The purpose of surface casing is to isolate freshwater zones so that they are not contaminated during drilling and completion. Surface casing is the most strictly regulated due to these environmental concerns, which can include regulation of casing depth and cement quality. A typical size of surface casing is .
Intermediate casing may be necessary on longer drilling intervals where necessary drilling mud weight to prevent blowouts may cause a hydrostatic pressure that can fracture shallower or deeper formations. Casing placement is selected so that the hydrostatic pressure of the drilling fluid remains at a pressure level that is between formation pore pressures and fracture pressures.
In order to reduce cost, a liner may be used which extends just above the shoe (bottom) of the previous casing interval and hung off downhole rather than at the surface. It may typically be 7", although many liners match the diameter of the production tubing.
Few wells actually produce through casing, since producing fluids can corrode steel or form deposits such as asphaltenes or paraffin waxes and the larger diameter can make flow unstable. Production tubing is therefore installed inside the last casing string and the tubing annulus is usually sealed at the bottom of the tubing by a packer. Tubing is easier to remove for maintenance, replacement, or for various types of workover operations. It is significantly lighter than casing and does not require a drilling rig to run in and out of hole; smaller "service rigs" are used for this purpose.
Cementing
Cementing is performed by circulating a cement slurry through the inside of the casing and out into the annulus through the casing shoe at the bottom of the casing string. In order to precisely place the cement slurry at a required interval on the outside of the casing, a plug is pumped with a displacement fluid behind the cement slurry column, which "bumps" in the casing shoe and prevents further flow of fluid through the shoe. This bump can be seen at surface as a pressure spike at the cement pump. To prevent the cement from flowing back into the inside of the casing, a float collar above the casing shoe acts as a check valve and prevents fluid from flowing up through the shoe from the annulus.
Casing Wear
A prolonged, recurrent axial and rotational movement within casing would cause wear to the casing interior, with the probability of blowouts, production loss, and other hazardous and costly complications.
The following conditions contribute to casing wear:
Drill pipe weight
Mud and additives
RPM and ROP
Tool joint coating
Well path and dogleg
The following are recommendations for preventative measures to minimize casing wear:
Minimization of dogleg severity and expect real dogleg at least 1.5 times higher than the planned value.
Usage of casing friendly tool joint materials.
Minimize rotor speed and use downhole motor.
Increase ROP.
Select proper mud type and add lubricants to minimize wear and friction.
Usage of drill pipe protectors.
Usage of thick wall casing in the anticipated wear section area.
Usage of software to reduce risks.
References
External links
Cementer
Schlumberger Oilfield Glossary: Casing
How Does Casing Work?
Oil wells
Drilling technology
Boreholes | Casing (borehole) | Chemistry | 1,435 |
4,677 | https://en.wikipedia.org/wiki/Binomial%20theorem | In elementary algebra, the binomial theorem (or binomial expansion) describes the algebraic expansion of powers of a binomial. According to the theorem, the power expands into a polynomial with terms of the form , where the exponents and are nonnegative integers satisfying and the coefficient of each term is a specific positive integer depending on and . For example, for ,
The coefficient in each term is known as the binomial coefficient or (the two have the same value). These coefficients for varying and can be arranged to form Pascal's triangle. These numbers also occur in combinatorics, where gives the number of different combinations (i.e. subsets) of elements that can be chosen from an -element set. Therefore is usually pronounced as " choose ".
Statement
According to the theorem, the expansion of any nonnegative integer power of the binomial is a sum of the form
where each is a positive integer known as a binomial coefficient, defined as
This formula is also referred to as the binomial formula or the binomial identity. Using summation notation, it can be written more concisely as
The final expression follows from the previous one by the symmetry of and in the first expression, and by comparison it follows that the sequence of binomial coefficients in the formula is symmetrical,
A simple variant of the binomial formula is obtained by substituting for , so that it involves only a single variable. In this form, the formula reads
Examples
The first few cases of the binomial theorem are:
In general, for the expansion of on the right side in the th row (numbered so that the top row is the 0th row):
the exponents of in the terms are (the last term implicitly contains );
the exponents of in the terms are (the first term implicitly contains );
the coefficients form the th row of Pascal's triangle;
before combining like terms, there are terms in the expansion (not shown);
after combining like terms, there are terms, and their coefficients sum to .
An example illustrating the last two points: with .
A simple example with a specific positive value of :
A simple example with a specific negative value of :
Geometric explanation
For positive values of and , the binomial theorem with is the geometrically evident fact that a square of side can be cut into a square of side , a square of side , and two rectangles with sides and . With , the theorem states that a cube of side can be cut into a cube of side , a cube of side , three rectangular boxes, and three rectangular boxes.
In calculus, this picture also gives a geometric proof of the derivative if one sets and interpreting as an infinitesimal change in , then this picture shows the infinitesimal change in the volume of an -dimensional hypercube, where the coefficient of the linear term (in ) is the area of the faces, each of dimension :
Substituting this into the definition of the derivative via a difference quotient and taking limits means that the higher order terms, and higher, become negligible, and yields the formula interpreted as
"the infinitesimal rate of change in volume of an -cube as side length varies is the area of of its -dimensional faces".
If one integrates this picture, which corresponds to applying the fundamental theorem of calculus, one obtains Cavalieri's quadrature formula, the integral – see proof of Cavalieri's quadrature formula for details.
Binomial coefficients
The coefficients that appear in the binomial expansion are called binomial coefficients. These are usually written and pronounced " choose ".
Formulas
The coefficient of is given by the formula
which is defined in terms of the factorial function . Equivalently, this formula can be written
with factors in both the numerator and denominator of the fraction. Although this formula involves a fraction, the binomial coefficient is actually an integer.
Combinatorial interpretation
The binomial coefficient can be interpreted as the number of ways to choose elements from an -element set (a combination). This is related to binomials for the following reason: if we write as a product
then, according to the distributive law, there will be one term in the expansion for each choice of either or from each of the binomials of the product. For example, there will only be one term , corresponding to choosing from each binomial. However, there will be several terms of the form , one for each way of choosing exactly two binomials to contribute a . Therefore, after combining like terms, the coefficient of will be equal to the number of ways to choose exactly elements from an -element set.
Proofs
Combinatorial proof
Expanding yields the sum of the products of the form where each is or . Rearranging factors shows that each product equals for some between and . For a given , the following are proved equal in succession:
the number of terms equal to in the expansion
the number of -character strings having in exactly positions
the number of -element subsets of
either by definition, or by a short combinatorial argument if one is defining as
This proves the binomial theorem.
Example
The coefficient of in
equals because there are three strings of length 3 with exactly two 's, namely,
corresponding to the three 2-element subsets of , namely,
where each subset specifies the positions of the in a corresponding string.
Inductive proof
Induction yields another proof of the binomial theorem. When , both sides equal , since and Now suppose that the equality holds for a given ; we will prove it for . For , let denote the coefficient of in the polynomial . By the inductive hypothesis, is a polynomial in and such that is if , and otherwise. The identity
shows that is also a polynomial in and , and
since if , then and . Now, the right hand side is
by Pascal's identity. On the other hand, if , then and , so we get . Thus
which is the inductive hypothesis with substituted for and so completes the inductive step.
Generalizations
Newton's generalized binomial theorem
Around 1665, Isaac Newton generalized the binomial theorem to allow real exponents other than nonnegative integers. (The same generalization also applies to complex exponents.) In this generalization, the finite sum is replaced by an infinite series. In order to do this, one needs to give meaning to binomial coefficients with an arbitrary upper index, which cannot be done using the usual formula with factorials. However, for an arbitrary number , one can define
where is the Pochhammer symbol, here standing for a falling factorial. This agrees with the usual definitions when is a nonnegative integer. Then, if and are real numbers with , and is any complex number, one has
When is a nonnegative integer, the binomial coefficients for are zero, so this equation reduces to the usual binomial theorem, and there are at most nonzero terms. For other values of , the series typically has infinitely many nonzero terms.
For example, gives the following series for the square root:
Taking , the generalized binomial series gives the geometric series formula, valid for :
More generally, with , we have for :
So, for instance, when ,
Replacing with yields:
So, for instance, when , we have for :
Further generalizations
The generalized binomial theorem can be extended to the case where and are complex numbers. For this version, one should again assume and define the powers of and using a holomorphic branch of log defined on an open disk of radius centered at . The generalized binomial theorem is valid also for elements and of a Banach algebra as long as , and is invertible, and .
A version of the binomial theorem is valid for the following Pochhammer symbol-like family of polynomials: for a given real constant , define and
for Then
The case recovers the usual binomial theorem.
More generally, a sequence of polynomials is said to be of binomial type if
for all ,
, and
for all , , and .
An operator on the space of polynomials is said to be the basis operator of the sequence if and for all . A sequence is binomial if and only if its basis operator is a Delta operator. Writing for the shift by operator, the Delta operators corresponding to the above "Pochhammer" families of polynomials are the backward difference for , the ordinary derivative for , and the forward difference for .
Multinomial theorem
The binomial theorem can be generalized to include powers of sums with more than two terms. The general version is
where the summation is taken over all sequences of nonnegative integer indices through such that the sum of all is . (For each term in the expansion, the exponents must add up to ). The coefficients are known as multinomial coefficients, and can be computed by the formula
Combinatorially, the multinomial coefficient counts the number of different ways to partition an -element set into disjoint subsets of sizes .
Multi-binomial theorem
When working in more dimensions, it is often useful to deal with products of binomial expressions. By the binomial theorem this is equal to
This may be written more concisely, by multi-index notation, as
General Leibniz rule
The general Leibniz rule gives the th derivative of a product of two functions in a form similar to that of the binomial theorem:
Here, the superscript indicates the th derivative of a function, . If one sets and , cancelling the common factor of from each term gives the ordinary binomial theorem.
History
Special cases of the binomial theorem were known since at least the 4th century BC when Greek mathematician Euclid mentioned the special case of the binomial theorem for exponent . Greek mathematician Diophantus cubed various binomials, including . Indian mathematician Aryabhata's method for finding cube roots, from around 510 AD, suggests that he knew the binomial formula for exponent .
Binomial coefficients, as combinatorial quantities expressing the number of ways of selecting objects out of without replacement (combinations), were of interest to ancient Indian mathematicians. The Jain Bhagavati Sutra (c. 300 BC) describes the number of combinations of philosophical categories, senses, or other things, with correct results up through (probably obtained by listing all possibilities and counting them) and a suggestion that higher combinations could likewise be found. The Chandaḥśāstra by the Indian lyricist Piṅgala (3rd or 2nd century BC) somewhat crypically describes a method of arranging two types of syllables to form metres of various lengths and counting them; as interpreted and elaborated by Piṅgala's 10th-century commentator Halāyudha his "method of pyramidal expansion" (meru-prastāra) for counting metres is equivalent to Pascal's triangle. Varāhamihira (6th century AD) describes another method for computing combination counts by adding numbers in columns. By the 9th century at latest Indian mathematicians learned to express this as a product of fractions , and clear statements of this rule can be found in Śrīdhara's Pāṭīgaṇita (8th–9th century), Mahāvīra's Gaṇita-sāra-saṅgraha (c. 850), and Bhāskara II's Līlāvatī (12th century).
The Persian mathematician al-Karajī (953–1029) wrote a now-lost book containing the binomial theorem and a table of binomial coefficients, often credited as their first appearance.
An explicit statement of the binomial theorem appears in al-Samawʾal's al-Bāhir (12th century), there credited to al-Karajī. Al-Samawʾal algebraically expanded the square, cube, and fourth power of a binomial, each in terms of the previous power, and noted that similar proofs could be provided for higher powers, an early form of mathematical induction. He then provided al-Karajī's table of binomial coefficients (Pascal's triangle turned on its side) up to and a rule for generating them equivalent to the recurrence relation . The Persian poet and mathematician Omar Khayyam was probably familiar with the formula to higher orders, although many of his mathematical works are lost. The binomial expansions of small degrees were known in the 13th century mathematical works of Yang Hui and also Chu Shih-Chieh. Yang Hui attributes the method to a much earlier 11th century text of Jia Xian, although those writings are now also lost.
In Europe, descriptions of the construction of Pascal's triangle can be found as early as Jordanus de Nemore's De arithmetica (13th century). In 1544, Michael Stifel introduced the term "binomial coefficient" and showed how to use them to express in terms of , via "Pascal's triangle". Other 16th century mathematicians including Niccolò Fontana Tartaglia and Simon Stevin also knew of it. 17th-century mathematician Blaise Pascal studied the eponymous triangle comprehensively in his Traité du triangle arithmétique.
By the early 17th century, some specific cases of the generalized binomial theorem, such as for , can be found in the work of Henry Briggs' Arithmetica Logarithmica (1624). Isaac Newton is generally credited with discovering the generalized binomial theorem, valid for any real exponent, in 1665, inspired by the work of John Wallis's Arithmetic Infinitorum and his method of interpolation. A logarithmic version of the theorem for fractional exponents was discovered independently by James Gregory who wrote down his formula in 1670.
Applications
Multiple-angle identities
For the complex numbers the binomial theorem can be combined with de Moivre's formula to yield multiple-angle formulas for the sine and cosine. According to De Moivre's formula,
Using the binomial theorem, the expression on the right can be expanded, and then the real and imaginary parts can be taken to yield formulas for and . For example, since
But De Moivre's formula identifies the left side with , so
which are the usual double-angle identities. Similarly, since
De Moivre's formula yields
In general,
and
There are also similar formulas using Chebyshev polynomials.
Series for e
The number is often defined by the formula
Applying the binomial theorem to this expression yields the usual infinite series for . In particular:
The th term of this sum is
As , the rational expression on the right approaches , and therefore
This indicates that can be written as a series:
Indeed, since each term of the binomial expansion is an increasing function of , it follows from the monotone convergence theorem for series that the sum of this infinite series is equal to .
Probability
The binomial theorem is closely related to the probability mass function of the negative binomial distribution. The probability of a (countable) collection of independent Bernoulli trials with probability of success all not happening is
An upper bound for this quantity is
In abstract algebra
The binomial theorem is valid more generally for two elements and in a ring, or even a semiring, provided that . For example, it holds for two matrices, provided that those matrices commute; this is useful in computing powers of a matrix.
The binomial theorem can be stated by saying that the polynomial sequence is of binomial type.
See also
Binomial approximation
Binomial distribution
Binomial inverse theorem
Binomial coefficient
Stirling's approximation
Tannery's theorem
Polynomials calculating sums of powers of arithmetic progressions
q-binomial theorem
Notes
References
Further reading
External links
Binomial Theorem by Stephen Wolfram, and "Binomial Theorem (Step-by-Step)" by Bruce Colletti and Jeff Bryant, Wolfram Demonstrations Project, 2007.
Factorial and binomial topics
Theorems about polynomials
Articles containing proofs | Binomial theorem | Mathematics | 3,297 |
75,227,434 | https://en.wikipedia.org/wiki/Efpeglenatide | Efpeglenatide is a GLP-1 receptor agonist under development for the treatment of type 2 diabetes and obesity and reducing the risk of cardiovascular incidents in people with these conditions. Its developer is Hanmi Pharmaceutical.
References
GLP-1 receptor agonists
Experimental diabetes drugs
Peptide therapeutics
Amino acids | Efpeglenatide | Chemistry | 65 |
61,863,261 | https://en.wikipedia.org/wiki/Stanley%20Robert%20Hart | Stanley Robert Hart (born 20 June 1935 in Swampscott, Massachusetts) is an American geologist, geochemist, leading international expert on mantle isotope geochemistry, and pioneer of chemical geodynamics.
Biography
Hart graduated from MIT with a bachelor's degree in geology in 1956 and a master's degree in geochemistry in 1957 from Caltech. In 1960 he received his doctorate in geochemistry from MIT with thesis Mineral ages and metamorphism under the supervision of Patrick M. Hurley. After a year as a Carnegie Fellow, Hart was from 1961 to 1975 at the Carnegie Institution in Washington, D.C. in the Department of Terrestrial Magnetism. From 1975 to 1989 he was a professor of Earth, Atmospheric and Planetary Sciences at MIT and from 1989 to 1992 a visiting professor there. From 1989 to 2007 he was a Senior Scientist in geology and geophysics at Woods Hole Oceanographic Institution. He retired from Woods Hole in 2007 as Scientist Emeritus.
Hart is a leading pioneer in the introduction of geochemistry into the Earth sciences. He developed comparative geochronology, which accounts for geological perturbations in various geochronometers. At the Carnegie Institution of Washington, he worked with George Wetherill, George Tilton, L. T. Aldrich, and G. L. Davis on mapping Precambrian rocks in the USA using comparative geochronology. There Hart became the leader of a group including Thomas Krogh, Albrecht Hofmann, Christopher Brooks, and others.
According to Claude Allègre:
Hart focused on the application of isotopic chemistry to age determination in geology, the geochemical evolution of mantle and oceanic lithosphere, and the geochemistry of strontium, neodymium, and lead isotopes in volcanic rocks. He also studied the long-term behavior of the chemical composition of the oceans due to their interaction with the oceanic crust and the experimental determination of fundamental geochemical properties such as mineral-melt partition coefficients in silicates and solid-state diffusion rates. In 1968, together with John S. Steinhart, he published the Steinhart-Hart equation, which provides a mathematical model of how the temperature and the electrical resistance of a thermistor vary, based upon 3 so-called Steinhart-Hart coefficients.
He was a co-editor from 1970 to 1972 of the Reviews of Geophysics, from 1970 to 1976 of the Geochimica et Cosmochimica Acta, and from 1975 to 1992 of Physics of the Earth and Planetary Interiors. In 1975/76 he chaired the US National Committee for Geochemistry. His doctoral students include Erik Hauri.
Hart has three children, one daughter from his first marriage, which ended in divorce in 1978, and a son and a daughter from his second marriage which began in 1980.
Awards and honors
1983 — Member of the National Academy of Sciences
1985–1987 — President of the Geochemical Society
1992 — V. M. Goldschmidt Award, Geochemical Society
1997 — Harry Hess Medal, American Geophysical Union
2005 — Fellow of the American Academy of Arts and Sciences
2008 — Arthur L. Day Prize and Lectureship
2016 — William Bowie Medal
Selected publications
References
20th-century American geologists
Massachusetts Institute of Technology School of Science alumni
California Institute of Technology alumni
Massachusetts Institute of Technology School of Science faculty
Geochemists
Members of the United States National Academy of Sciences
Fellows of the American Academy of Arts and Sciences
Fellows of the American Geophysical Union
1935 births
Living people
Presidents of the Geochemical Society
Recipients of the V. M. Goldschmidt Award | Stanley Robert Hart | Chemistry | 729 |
10,347,116 | https://en.wikipedia.org/wiki/NGC%204125 | NGC 4125 is an elliptical galaxy in the constellation Draco. It was discovered on 4 January 1850 by English astronomer John Russell Hind.
On 28 May 2016, the telescope KAIT discovered the supernova SN 2016coj (type Ia, mag. 14.8) in this galaxy. After detection, it became brighter over the course of several days. It reached magnitude 13, making it the brightest supernova of 2016.
See also
List of NGC objects (4001–5000)
References
External links
NGC 4125
Shell galaxies
Draco (constellation)
4125
07118
12055+6527
038524
+11-15-027
Discoveries by John Russell Hind
Astronomical objects discovered in 1850 | NGC 4125 | Astronomy | 143 |
36,387,287 | https://en.wikipedia.org/wiki/C20H17F3N2O4 | {{DISPLAYTITLE:C20H17F3N2O4}}
The molecular formula C20H17F3N2O4 (molar mass: 406.355 g/mol) may refer to:
Floctafenine
Tasquinimod
Molecular formulas | C20H17F3N2O4 | Physics,Chemistry | 62 |
34,028,000 | https://en.wikipedia.org/wiki/HIP%205158%20c | HIP 5158 c is an extrasolar planet, orbiting the 10th magnitude K-type main sequence star HIP 5158 about 135 lightyears away from Earth, in the constellation Cetus.
It orbits its primary star at an average distance (semi-major axis) of 7.7 AU. The actual orbital period is unknown, but is estimated to be somewhere in between 9,018 and 12,200 days. It travels with an eccentricity of 0.14. It also has an estimated minimal mass 15.04 . It was discovered by HARPS on October 19, 2009, together with 29 other planets, and confirmed in May 2011.
Being heavier than 13 , the HIP 5158 c can be classified either as brown dwarf or as superjovian planet.
References
20091019
Cetus | HIP 5158 c | Astronomy | 162 |
47,447,624 | https://en.wikipedia.org/wiki/Penicillium%20rubefaciens | Penicillium rubefaciens is a species of fungus in the genus Penicillium which has been isolated from sandy soil.
References
Further reading
rubefaciens
Fungi described in 1982
Fungus species | Penicillium rubefaciens | Biology | 43 |
21,045,118 | https://en.wikipedia.org/wiki/Haefliger%20structure | In mathematics, a Haefliger structure on a topological space is a generalization of a foliation of a manifold, introduced by André Haefliger in 1970. Any foliation on a manifold induces a special kind of Haefliger structure, which uniquely determines the foliation.
Definition
A codimension- Haefliger structure on a topological space consists of the following data:
a cover of by open sets ;
a collection of continuous maps ;
for every , a diffeomorphism between open neighbourhoods of and with ;
such that the continuous maps from to the sheaf of germs of local diffeomorphisms of satisfy the 1-cocycle condition
for
The cocycle is also called a Haefliger cocycle.
More generally, , piecewise linear, analytic, and continuous Haefliger structures are defined by replacing sheaves of germs of smooth diffeomorphisms by the appropriate sheaves.
Examples and constructions
Pullbacks
An advantage of Haefliger structures over foliations is that they are closed under pullbacks. More precisely, given a Haefliger structure on , defined by a Haefliger cocycle , and a continuous map , the pullback Haefliger structure on is defined by the open cover and the cocycle . As particular cases we obtain the following constructions:
Given a Haefliger structure on and a subspace , the restriction of the Haefliger structure to is the pullback Haefliger structure with respect to the inclusion
Given a Haefliger structure on and another space , the product of the Haefliger structure with is the pullback Haefliger structure with respect to the projection
Foliations
Recall that a codimension- foliation on a smooth manifold can be specified by a covering of by open sets , together with a submersion from each open set to , such that for each there is a map from to local diffeomorphisms with
whenever is close enough to . The Haefliger cocycle is defined by
germ of at u.
As anticipated, foliations are not closed in general under pullbacks but Haefliger structures are. Indeed, given a continuous map , one can take pullbacks of foliations on provided that is transverse to the foliation, but if is not transverse the pullback can be a Haefliger structure that is not a foliation.
Classifying space
Two Haefliger structures on are called concordant if they are the restrictions of Haefliger structures on to and .
There is a classifying space for codimension- Haefliger structures which has a universal Haefliger structure on it in the following sense. For any topological space and continuous map from to the pullback of the universal Haefliger structure is a Haefliger structure on . For well-behaved topological spaces this induces a 1:1 correspondence between homotopy classes of maps from to and concordance classes of Haefliger structures.
References
Differential geometry
Smooth manifolds
Topological spaces
Structures on manifolds
Foliations | Haefliger structure | Mathematics | 651 |
3,420,533 | https://en.wikipedia.org/wiki/Entrainment%20%28hydrodynamics%29 | Entrainment is the transport of fluid across an interface between two bodies of fluid by a shear-induced turbulent flux. Entrainment is important in turbulent jets, plumes, and gravity currents, and is an ongoing topic of research.
History
The entrainment hypothesis was first used as a model for flow in plumes by G. I. Taylor. He was studying the use of oil drum fires to clear fog from airplane runways during World War II.
It became a common model of turbulence closure used in environmental and geophysical fluid mechanics.
Applications
Eductors or eductor-jet pumps make use of entrainment. They are used on board ships to pump out flooded compartments: seawater is pumped to the eductor and forced through a jet, and any fluid at the inlet of the eductor is carried along to the outlet, and then up and out of the compartment. Eductors can pump out whatever can flow through them, including water, oil, and small pieces of wood. Another example is the pump-jet, which is used for marine propulsion. Jet pumps are also used to circulate reactor coolant in several designs of boiling water nuclear reactor.
In power generation, this phenomenon is used in steam jet air ejectors to maintain condenser vacuum by removing non-condensible gases from the condenser.
In theorical aerodynamics applications the entrainment velocity, which expresses the rate of change of the entrainment, is often used to solve the von Kármán integral for turbulent boundary layers.
References
Fluid dynamics
Turbulence | Entrainment (hydrodynamics) | Chemistry,Engineering | 321 |
353,697 | https://en.wikipedia.org/wiki/Sonic%20hedgehog%20protein | Sonic hedgehog protein (SHH) is encoded for by the SHH gene. The protein is named after the video game character Sonic the Hedgehog.
This signaling molecule is key in regulating embryonic morphogenesis in all animals. SHH controls organogenesis and the organization of the central nervous system, limbs, digits and many other parts of the body. Sonic hedgehog is a morphogen that patterns the developing embryo using a concentration gradient characterized by the French flag model. This model has a non-uniform distribution of SHH molecules which governs different cell fates according to concentration. Mutations in this gene can cause holoprosencephaly, a failure of splitting in the cerebral hemispheres, as demonstrated in an experiment using SHH knock-out mice in which the forebrain midline failed to develop and instead only a single fused telencephalic vesicle resulted.
Sonic hedgehog still plays a role in differentiation, proliferation, and maintenance of adult tissues. Abnormal activation of SHH signaling in adult tissues has been implicated in various types of cancers including breast, skin, brain, liver, gallbladder and many more.
Discovery and naming
The hedgehog gene (hh) was first identified in the fruit fly Drosophila melanogaster in the classic Heidelberg screens of Christiane Nüsslein-Volhard and Eric Wieschaus, as published in 1980. These screens, which led to the researchers winning a Nobel Prize in 1995 along with developmental geneticist Edward B. Lewis, identified genes that control the segmentation pattern of the Drosophila embryos. The hh loss of function mutant phenotype causes the embryos to be covered with denticles, i.e. small pointy projections resembling the spikes of a hedgehog. Investigations aimed at finding a hedgehog equivalent in vertebrates by Philip Ingham, Andrew P. McMahon and Clifford Tabin revealed three homologous genes.
Two of these genes, desert hedgehog and Indian hedgehog, were named for species of hedgehogs, while sonic hedgehog was named after the video game character Sonic the Hedgehog. The gene was named by Robert Riddle, a postdoctoral fellow at the Tabin Lab, after his wife Betsy Wilder came home with a magazine containing an advert for the first game in the series, Sonic the Hedgehog (1991). In the zebrafish, two of the three vertebrate hh genes are duplicated: SHH a and SHH b (formerly described as tiggywinkle hedgehog, named for Mrs. Tiggy-Winkle, a character from Beatrix Potter's books for children) and ihha and ihhb (formerly described as echidna hedgehog, named for the spiny anteater and not for the character Knuckles the Echidna in the Sonic franchise).
Function
Of the hh homologues, SHH has been found to have the most critical roles in development, acting as a morphogen involved in patterning many systems—including the anterior pituitary, pallium of the brain, spinal cord, lungs, teeth and the thalamus by the zona limitans intrathalamica. In vertebrates, the development of limbs and digits depends on the secretion of sonic hedgehog by the zone of polarizing activity, located on the posterior side of the embryonic limb bud. Mutations in the human sonic hedgehog gene SHH cause holoprosencephaly type 3 HPE3, as a result of the loss of the ventral midline. The sonic hedgehog transcription pathway has also been linked to the formation of specific kinds of cancerous tumors, including the embryonic cerebellar tumor and medulloblastoma, as well as the progression of prostate cancer tumours. For SHH to be expressed in the developing embryo limbs, a morphogen called fibroblast growth factors must be secreted from the apical ectodermal ridge.
Sonic hedgehog has also been shown to act as an axonal guidance cue. It has been demonstrated that SHH attracts commissural axons at the ventral midline of the developing spinal cord. Specifically, SHH attracts retinal ganglion cell (RGC) axons at low concentrations and repels them at higher concentrations. The absence (non-expression) of SHH has been shown to control the growth of nascent hind limbs in cetaceans (whales and dolphins).
The SHH gene is a member of the hedgehog gene family with five variations of DNA sequence alterations or splice variants. SHH is located on chromosome seven and initiates the production of Sonic Hedgehog protein. This protein sends short- and long-range signals to embryonic tissues to regulate development. If the SHH gene is mutated or absent, the protein Sonic Hedgehog cannot do its job properly. Sonic hedgehog contributes to cell growth, cell specification and formation, structuring and organization of the body plan. This protein functions as a vital morphogenic signaling molecule and plays an important role in the formation of many different structures in developing embryos. The SHH gene affects several major organ systems, such as the nervous system, cardiovascular system, respiratory system and musculoskeletal system. Mutations in the SHH gene can cause malformation of components of these systems, which can result in major problems in the developing embryo. The brain and eyes, for example, can be significantly impacted by mutations in this gene and cause disorders such as Microphthalmia and Holoprosencephaly. Microphthalmia is a condition that affects the eyes, which results in small, underdeveloped tissues in one or both eyes. This can lead to issues ranging from a coloboma to a single small eye to the absence of eyes altogether. Holoprosencephaly is a condition most commonly caused by a mutation of the SHH gene that causes improper separation or turn of the left and right brain and facial dysmorphia. Many systems and structures rely heavily on proper expression of the SHH gene and subsequent sonic hedgehog protein, earning it the distinction of being an essential gene to development.
Patterning of the central nervous system
The sonic hedgehog (SHH) signaling molecule assumes various roles in patterning the central nervous system (CNS) during vertebrate development. One of the most characterized functions of SHH is its role in the induction of the floor plate and diverse ventral cell types within the neural tube. The notochord—a structure derived from the axial mesoderm—produces SHH, which travels extracellularly to the ventral region of the neural tube and instructs those cells to form the floor plate. Another view of floor plate induction hypothesizes that some precursor cells located in the notochord are inserted into the neural plate before its formation, later giving rise to the floor plate.
The neural tube itself is the initial groundwork of the vertebrate CNS, and the floor plate is a specialized structure, located at the ventral midpoint of the neural tube. Evidence supporting the notochord as the signaling center comes from studies in which a second notochord is implanted near a neural tube in vivo, leading to the formation of an ectopic floor plate within the neural tube.
Sonic hedgehog is the secreted protein that mediates signaling activities of the notochord and floor plate. Studies involving ectopic expression of SHH in vitro and in vivo result in floor plate induction and differentiation of motor neuron and ventral interneurons. On the other hand, mice mutants for SHH lack ventral spinal cord characteristics. In vitro blocking of SHH signaling using antibodies against it shows similar phenotypes. SHH exerts its effects in a concentration-dependent manner, so that a high concentration of SHH results in a local inhibition of cellular proliferation. This inhibition causes the floor plate to become thin compared to the lateral regions of the neural tube. Lower concentration of SHH results in cellular proliferation and induction of various ventral neural cell types. Once the floor plate is established, cells residing in this region will subsequently express SHH themselves, generating a concentration gradient within the neural tube.
Although there is no direct evidence of a SHH gradient, there is indirect evidence via the visualization of Patched (Ptc) gene expression, which encodes for the ligand binding domain of the SHH receptor throughout the ventral neural tube. In vitro studies show that incremental two- and threefold changes in SHH concentration give rise to motor neuron and different interneuronal subtypes as found in the ventral spinal cord. These incremental changes in vitro correspond to the distance of domains from the signaling tissue (notochord and floor plate) which subsequently differentiates into different neuronal subtypes as it occurs in vitro. Graded SHH signaling is suggested to be mediated through the Gli family of proteins, which are vertebrate homologues of the Drosophila zinc-finger-containing transcription factor Cubitus interruptus (Ci). Ci is a crucial mediator of hedgehog (Hh) signaling in Drosophila. In vertebrates, three different Gli proteins are present, viz. Gli1, Gli2 and Gli3, which are expressed in the neural tube. Mice mutants for Gli1 show normal spinal cord development, suggesting that it is dispensable for mediating SHH activity. However, Gli2 mutant mice show abnormalities in the ventral spinal cord, with severe defects in the floor plate and ventral-most interneurons (V3). Gli3 antagonizes SHH function in a dose-dependent manner, promoting dorsal neuronal subtypes. SHH mutant phenotypes can be rescued in a SHH/Gli3 double mutant. Gli proteins have a C-terminal activation domain and an N-terminal repressive domain.
SHH is suggested to promote the activation function of Gli2 and inhibit repressive activity of Gli3. SHH also seems to promote the activation function of Gli3, but this activity is not strong enough. The graded concentration of SHH gives rise to graded activity of Gli 2 and Gli3, which promote ventral and dorsal neuronal subtypes in the ventral spinal cord. Evidence from Gli3 and SHH/Gli3 mutants show that SHH primarily regulates the spatial restriction of progenitor domains rather than being inductive, as SHH/Gli3 mutants show intermixing of cell types.
SHH also induces other proteins with which it interacts, and these interactions can influence the sensitivity of a cell towards SHH. Hedgehog-interacting protein (HHIP) is induced by SHH, which in turn attenuates its signaling activity. Vitronectin is another protein that is induced by SHH; it acts as an obligate co-factor for SHH signaling in the neural tube.
There are five distinct progenitor domains in the ventral neural tube: V3 interneurons, motor neurons (MN), V2, V1, and V0 interneurons (in ventral to dorsal order). These different progenitor domains are established by "communication" between different classes of homeobox transcription factors. (See Trigeminal Nerve.) These transcription factors respond to SHH gradient concentration. Depending upon the nature of their interaction with SHH, they are classified into two groups—class I and class II—and are composed of members from the Pax, Nkx, Dbx and Irx families. Class I proteins are repressed at different thresholds of SHH delineating ventral boundaries of progenitor domains, while class II proteins are activated at different thresholds of SHH delineating the dorsal limit of domains. Selective cross-repressive interactions between class I and class II proteins give rise to five cardinal ventral neuronal subtypes.
It is important to note that SHH is not the only signaling molecule exerting an effect on the developing neural tube. Many other molecules, pathways and mechanisms are active (e.g., RA, FGF, BMP), and complex interactions between SHH and other molecules are possible. BMPs are suggested to play a critical role in determining the sensitivity of neural cell to SHH signaling. Evidence supporting this comes from studies using BMP inhibitors that ventralize the fate of the neural plate cell for a given SHH concentration. On the other hand, mutation in BMP antagonists (e.g., noggin) produces severe defects in the ventral-most characteristics of the spinal cord, followed by ectopic expression of BMP in the ventral neural tube. Interactions of SHH with Fgf and RA have not yet been studied in molecular detail.
Morphogenetic activity
The concentration- and time-dependent, cell-fate-determining activity of SHH in the ventral neural tube makes it a prime example of a morphogen. In vertebrates, SHH signaling in the ventral portion of the neural tube is most notably responsible for the induction of floor plate cells and motor neurons. SHH emanates from the notochord and ventral floor plate of the developing neural tube to create a concentration gradient that spans the dorso-ventral axis and is antagonized by an inverse Wnt gradient, which specifies the dorsal spinal cord. Higher concentrations of the SHH ligand are found in the most ventral aspects of the neural tube and notochord, while lower concentrations are found in the more dorsal regions of the neural tube. The SHH concentration gradient has been visualized in the neural tube of mice engineered to express a SHH::GFP fusion protein to show this graded distribution of SHH during the time of ventral neural tube patterning.
It is thought that the SHH gradient works to elicit multiple different cell fates by a concentration- and time-dependent mechanism that induces a variety of transcription factors in the ventral progenitor cells. Each of the ventral progenitor domains expresses a highly individualized combination of transcription factors—Nkx2.2, Olig2, Nkx6.1, Nkx6.2, Dbx1, Dbx2, Irx3, Pax6, and Pax7—that is regulated by the SHH gradient. These transcription factors are induced sequentially along the SHH concentration gradient with respect to the amount and time of exposure to SHH ligand. As each population of progenitor cells responds to the different levels of SHH protein, they begin to express a unique combination of transcription factors that leads to neuronal cell fate differentiation. This SHH-induced differential gene expression creates sharp boundaries between the discrete domains of transcription factor expression, which ultimately patterns the ventral neural tube.
The spatial and temporal aspect of the progressive induction of genes and cell fates in the ventral neural tube is illustrated by the expression domains of two of the most well-characterized transcription factors, Olig2 and Nkx2.2. Early in development, the cells at the ventral midline have only been exposed to a low concentration of SHH for a relatively short time and express the transcription factor Olig2. The expression of Olig2 rapidly expands in a dorsal direction concomitantly with the continuous dorsal extension of the SHH gradient over time. However, as the morphogenetic front of SHH ligand moves and begins to grow more concentrated, cells that are exposed to higher levels of the ligand respond by switching off Olig2 and turning on Nkx2.2, creating a sharp boundary between the cells expressing the transcription factor Nkx2.2 ventral to the cells expressing Olig2. It is in this way that each of the domains of the six progenitor cell populations are thought to be successively patterned throughout the neural tube by the SHH concentration gradient. Mutual inhibition between pairs of transcription factors expressed in neighboring domains contributes to the development of sharp boundaries; however, in some cases, inhibitory relationship has been found even between pairs of transcription factors from more distant domains. Particularly, NKX2-2 expressed in the V3 domain is reported to inhibit IRX3 expressed in V2 and more dorsal domains, although V3 and V2 are separated by a further domain termed MN.
SHH expression in the frontonasal ectodermal zone (FEZ), which is a signaling center that is responsible for the patterned development of the upper jaw, regulates craniofacial development mediating through the miR-199 family in the FEZ. Specifically, SHH-dependent signals from the brain regulate genes of the miR-199 family with downregulations of the miR-199 genes increasing SHH expression and resulting in wider faces, while upregulations of the miR-199 genes decrease SHH expression resulting in narrow faces.
Tooth development
SHH plays an important role in organogenesis and, most importantly, craniofacial development. Being that SHH is a signaling molecule, it primarily works by diffusion along a concentration gradient, affecting cells in different manners. In early tooth development, SHH is released from the primary enamel knot—a signaling center—to provide positional information in both a lateral and planar signaling pattern in tooth development and regulation of tooth cusp growth. SHH in particular is needed for growth of epithelial cervical loops, where the outer and inner epitheliums join and form a reservoir for dental stem cells. After the primary enamel knots are apoptosed, the secondary enamel knots are formed. The secondary enamel knots secrete SHH in combination with other signaling molecules to thicken the oral ectoderm and begin patterning the complex shapes of the crown of a tooth during differentiation and mineralization. In a knockout gene model, absence of SHH is indicative of holoprosencephaly. However, SHH activates downstream molecules of Gli2 and Gli3. Mutant Gli2 and Gli3 embryos have abnormal development of incisors that are arrested in early tooth development as well as small molars.
Lung development
Although SHH is most commonly associated with brain and limb digit development, it is also important in lung development. Studies using qPCR and knockouts have demonstrated that SHH contributes to embryonic lung development. The mammalian lung branching occurs in the epithelium of the developing bronchi and lungs. SHH expressed throughout the foregut endoderm (innermost of three germ layers) in the distal epithelium, where the embryonic lungs are developing. This suggests that SHH is partially responsible for the branching of the lungs. Further evidence of SHH's role in lung branching has been seen with qPCR. SHH expression occurs in the developing lungs around embryonic day 11 and is strongly expressed in the buds of the fetal lungs but low in the developing bronchi. Mice who are deficient in SHH can develop tracheoesophageal fistula (abnormal connection of the esophagus and trachea). Additionally, a double (SHH-/- ) knockout mouse model exhibited poor lung development. The lungs of the SHH double knockout failed to undergo lobation and branching (i.e., the abnormal lungs only developed one branch, compared to an extensively branched phenotype of the wildtype).
Potential regenerative function
Sonic hedgehog may play a role in mammalian hair cell regeneration. By modulating retinoblastoma protein activity in rat cochlea, sonic hedgehog allows mature hair cells that normally cannot return to a proliferative state to divide and differentiate. Retinoblastoma proteins suppress cell growth by preventing cells from returning to the cell cycle, thereby preventing proliferation. Inhibiting the activity of Rb seems to allow cells to divide. Therefore, sonic hedgehog—identified as an important regulator of Rb—may also prove to be an important feature in regrowing hair cells after damage.
SHH is important for regulating dermal adipogenesis by hair follicle transit-amplifying cells (HF-TACs). Specifically, SHH induces dermal angiogenesis by acting directly on adipocyte precursors and promoting their proliferation through their expression of the peroxisome proliferator-activated receptor γ (Pparg) gene.
Processing
SHH undergoes a series of processing steps before it is secreted from the cell. Newly synthesised SHH weighs 45 kDa and is referred to as the preproprotein. As a secreted protein, it contains a short signal sequence at its N-terminus, which is recognised by the signal recognition particle during the translocation into the endoplasmic reticulum (ER), the first step in protein secretion. Once translocation is complete, the signal sequence is removed by signal peptidase in the ER. There, SHH undergoes autoprocessing to generate a 20 kDa N-terminal signaling domain (SHH-N) and a 25 kDa C-terminal domain with no known signaling role. The cleavage is catalysed by a protease within the C-terminal domain. During the reaction, a cholesterol molecule is added to the C-terminus of SHH-N. Thus, the C-terminal domain acts as an intein and a cholesterol transferase. Another hydrophobic moiety, a palmitate, is added to the alpha-amine of N-terminal cysteine of SHH-N. This modification is required for efficient signaling, resulting in a 30-fold increase in potency over the non-palmitylated form and is carried out by a member of the membrane-bound O-acyltransferase family Protein-cysteine N-palmitoyltransferase HHAT.
Robotnikinin
A potential inhibitor of the Hedgehog signaling pathway has been found and dubbed "Robotnikinin"—after Sonic the Hedgehog's nemesis and the main antagonist of the Sonic the Hedgehog game series, Dr. Ivo "Eggman" Robotnik.
Former controversy surrounding name
The gene has been linked to a condition known as holoprosencephaly, which can result in severe brain, skull and facial defects, causing a few clinicians and scientists to criticize the name on the grounds that it sounds too frivolous. It has been noted that mention of a mutation in a sonic hedgehog gene might not be well received in a discussion of a serious disorder with a patient or their family. This controversy has largely died down, and the name is now generally seen as a humorous relic of the time before the rise of fast, cheap complete genome sequencing and standardized nomenclature. The problem of the "inappropriateness" of the names of genes such as "Mothers against decapentaplegic," "Lunatic fringe," and "Sonic hedgehog" is largely avoided by using standardized abbreviations when speaking with patients and their families.
Gallery
See also
Pikachurin, a retinal protein named after Pikachu
Zbtb7, an oncogene which was originally named "Pokémon"
References
Further reading
External links
An introductory article on SHH at Davidson College
Rediscovering biology: Unit 7 Genetics of development .. Expert interview transcripts interview with John Incardona PhD .. explanation of the discovery and naming of the sonic hedgehog gene
‘Sonic Hedgehog’ sounded funny at first .. New York Times November 12, 2006 ..
GeneReviews/NCBI/NIH/UW entry on Anophthalmia / Microphthalmia Overview
SHH – sonic hedgehog US National Library of Medicine
Proteins
Morphogens
HINT domain
Cell signaling
Ligands (biochemistry)
Genes on human chromosome 7
Sonic the Hedgehog | Sonic hedgehog protein | Chemistry,Biology | 4,899 |
53,706,715 | https://en.wikipedia.org/wiki/Event%20storming | Event storming is a workshop-based method to quickly find out what is happening in the domain of a software program.
Compared to other methods it is extremely lightweight and intentionally requires no support by a computer.
The result is expressed in sticky notes on a wide wall.
The business process is "stormed out" as a series of domain events which are denoted as orange stickies.
It was invented by Alberto Brandolini in the context of domain-driven design (DDD).
Event storming can be used as a means for business process modeling and requirements engineering.
The idea is to bring together software developers and domain experts and learn from each other.
The name was chosen to show that the focus should be on the domain events and the method works similar to brainstorming or agile modeling's model storming.
Requirements
It is important for an event storming workshop to have the right people present.
This includes people who know the questions to ask (typically developers) and those who know the answers (domain experts, product owners).
The modeling will be placed on a wide wall with a roll of paper rolled out on it.
The sticky notes will be placed on this paper.
You will require at least 5 distinct colors for the sticky notes.
Steps
The first step is to find the domain events and write them on orange sticky notes.
When all domain events are found the second step is to find the command that caused each of the domain events. Commands are written on blue notes and placed directly before the corresponding domain event.
In the third step the aggregates within which commands are executed and where events happen are identified.
The aggregates are written in yellow stickies.
The concepts gathered during an event storming session fall into several categories, each with its own colour of sticky note:
An event that occurs in the business process. Written in past tense.
A person who executes a command through a view.
Processes a command according to business rules and logic. Creates one or more domain events.
A command executed by a user through a view on an aggregate that results in the creation of a domain event.
Cluster of domain objects that can be treated as a single unit.
A third-party service provider such as a payment gateway or shipping company.
A view that users interact with to carry out a task in the system.
Example notes
These are examples, these would be different for different organizations.
Domain events
Actors
Commands
Aggregates
External systems
Views
Errors
Example
Users
CreateAccount
AccountCreated
Signup
Result
As a result, the business process can be seen on the modeling space.
But more important is the knowledge that was built in the minds of the participants.
References
External links
https://miro.com/miroverse/event-storming/
Collaboration
Group problem solving methods
Software architecture
Software design | Event storming | Engineering | 562 |
16,735,911 | https://en.wikipedia.org/wiki/Jupiter%20radius | The Jupiter radius or Jovian radius ( or ) has a value of , or 11.2 Earth radii () (one Earth radius equals ). The Jupiter radius is a unit of length used in astronomy to describe the radii of gas giants and some exoplanets. It is also used in describing brown dwarfs.
The general shape of the planet Jupiter has been directly measured from radio occultations of passing spacecraft, starting with the Pioneer and Voyager missions. This gives an overall margin of error of about 5 km. Estimates of the radii at one bar pressure are then determined through extrapolation. The planet Jupiter has the approximate shape of an oblate spheroid, which is mainly set by the rate of rotation. This gives a difference of about 10% between the polar and equatorial radii. The polar radius has been determined with an accuracy of ±10 km, as of 1987. Density fluctuations within the planet can create variations in the equatorial radius of up to 30 km. The winds in the outer atmosphere can vary the radius by up to 4 km.
In 2015, the International Astronomical Union defined the nominal equatorial Jovian radius to remain constant regardless of subsequent improvements in measurement precision of . This constant is defined as exactly:
=
Similarly, the nominal polar Jovian radius is defined to be exactly:
=
These values correspond to the radius of Jupiter at 1 bar of pressure. The common usage is to refer to the equatorial radius, unless the polar radius is specifically needed.
Comparison
For comparison, one Solar radius is equivalent to:
400 Lunar radius ()
109 Earth radius ()
9.955 Jupiter radius ()
References
Planetary science
Units of measurement in astronomy
Radius
Units of length
Radii | Jupiter radius | Astronomy,Mathematics | 347 |
8,447,410 | https://en.wikipedia.org/wiki/Complementarity-determining%20region | Complementarity-determining regions (CDRs) are polypeptide segments of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively. CDRs are where these molecules bind to their specific antigen and their structure/sequence determines the binding activity of the respective antibody. A set of CDRs constitutes a paratope, or the antigen-binding site. As the most variable parts of the molecules, CDRs are crucial to the diversity of antigen specificities generated by lymphocytes.
Binding Affinity
Antibody-antigen interactions are highly specific and those that have high affinity will interact with increased bond strength and trigger downstream immune responses. The strength of the bond between the epitope of the antigen and the paratope of the antibody will determine the affinity of the interaction.
Location and structure
There are three CDRs (CDR1, CDR2 and CDR3), arranged non-consecutively, on the amino acid sequence of a variable domain of an antigen receptor. Three can be found on the Light-chain, named L1 through L3, and three on the Heavy-chain, named H1 through H3. Since the antigen receptors are typically composed of two variable domains (on two different polypeptide chains, heavy and light chain), there are six CDRs for each antigen receptor that can collectively come into contact with the antigen. A single antibody molecule has two antigen receptors and therefore contains twelve CDRs total. There are three CDR loops per variable domain in antibodies. Sixty CDRs can be found on a pentameric IgM molecule, which is composed of five antibodies and has increased avidity as a result of the collective affinity of all antigen-binding sites combined.
Since most sequence variation associated with immunoglobulins and T cell receptors are found in the CDRs, these regions are sometimes referred to as hypervariable regions. Within the variable domain, CDR1 and CDR2 are found in the variable (V) region of a polypeptide chain, and CDR3 includes some of V, all of diversity (D, heavy chains only) and joining (J) regions. CDR3 is the most variable. The V region sequence undergoes rearrangement during B-cell development, called somatic recombination. This rearrangement of the V-region is where the CDR-L3 and CDR-H3 are encoded and diversified, whereas the other four CDRs are generated in the germ-line. The diversification of the CDR-H3 will ultimately give antibodies their specificity, and ability to recognize antigens
Other factors contribute to the antibody-antigen interaction, including amino acid residues. Residues located in particular positions of a CDR loop are used to classify canonical structures. Uncharged-polar residues, especially Serine and Tyrosine, are found in CDRs at a high concentration ratio. These residues significantly contribute to the direct hydrogen bonds between the antigen and the antibody. Hydrogen bond interactions will induce the enzymatic activity of an enzyme; therefore, the more hydrogen bonds that are present at the antibody-antigen binding site will result in a stronger, more stable binding structure.
The tertiary structure of an antibody is important to analyze and design new antibodies. The structure and sequence of all six CDRs combined will determine the binding activity of the antigen receptor on an antibody or T-cell Receptor. CDRs have been separated into canonical classes based on their varying loop lengths, which are commonly used to differentiate the CDRs from each other. The structural relationship between different length CDRS is based on length-independent components, such as their sequence, and can further characterize CDRs. The loops, or three-dimensional structures of the non-H3 CDRs (all CDRs but H3) of antibodies have been clustered and classified by Chothia et al. and more recently by North et al. Homology modeling is a computational method to build tertiary structures from amino-acid sequences. The so-called H3-rules are empirical rules to build models of CDR3.
See also
Framework region
Hypervariable region
References
External links
PyIgClassify -- server for classification of CDR conformations
Amino acids
Antibodies
Immunology | Complementarity-determining region | Chemistry,Biology | 878 |
54,507,206 | https://en.wikipedia.org/wiki/Dual%20photon | In theoretical physics, the dual photon is a hypothetical elementary particle that is a dual of the photon under electric–magnetic duality which is predicted by some theoretical models, including M-theory.
It has been shown that including magnetic monopole in Maxwell's equations introduces a singularity. The only way to avoid the singularity is to include a second four-vector potential, called dual photon, in addition to the usual four-vector potential, photon. Additionally, it is found that the standard Lagrangian of electromagnetism is not dual symmetric (i.e. symmetric under rotation between electric and magnetic charges) which causes problems for the energy–momentum, spin, and orbital angular momentum tensors. To resolve this issue, a dual symmetric Lagrangian of electromagnetism has been proposed, which has a self-consistent separation of the spin and orbital degrees of freedom. The Poincaré symmetries imply that the dual electromagnetism naturally makes self-consistent conservation laws.
Dual electromagnetism
The free electromagnetic field is described by a covariant antisymmetric tensor of rank 2 by
where is the electromagnetic potential.
The dual electromagnetic field is defined as
where denotes the Hodge dual, and is the Levi-Civita tensor
For the electromagnetic field and its dual field, we have
Then, for a given gauge field , the dual configuration is defined as
where the field potential of the dual photon, and non-locally linked to the original field potential .
p-form electrodynamics
A p-form generalization of Maxwell's theory of electromagnetism is described by a gauge-invariant 2-form defined as
.
which satisfies the equation of motion
where is the Hodge star operator.
This implies the following action in the spacetime manifold :
where is the dual of the gauge-invariant 2-form for the electromagnetic field.
Dark photon
The dark photon is a spin-1 boson associated with a U(1) gauge field, which could be massless and behaves like electromagnetism. But, it could be unstable and massive, quickly decays into electron–positron pairs, and interact with electrons.
The dark photon was first suggested in 2008 by Lotty Ackerman, Matthew R. Buckley, Sean M. Carroll, and Marc Kamionkowski to explain the 'g–2 anomaly' in experiment E821 at Brookhaven National Laboratory. Nevertheless, it was ruled out in some experiments such as the PHENIX detector at the Relativistic Heavy Ion Collider at Brookhaven.
In 2015, the Hungarian Academy of Sciences's Institute for Nuclear Research in Debrecen, Hungary, suggested the existence of a new, light spin-1 boson, dubbed the X17 particle, 34 times heavier than the electron that decays into a pair of electron and positron with a combined energy of 17 MeV. In 2016, it was proposed that it is an X-boson with a mass of 16.7 MeV that explains the g−2 muon anomaly.
See also
Magnetic photon, a different extension for magnetic monopoles
List of hypothetical particles
References
Gauge bosons
Bosons
String theory
Hypothetical elementary particles
Quantum electrodynamics
Magnetic monopoles
Force carriers | Dual photon | Physics,Astronomy | 665 |
73,964,415 | https://en.wikipedia.org/wiki/NATO%20Star | The NATO Star is a sculpture situated in the court of honor of the North Atlantic Treaty Organization's (NATO) headquarters in Brussels, Belgium.
The sculpture was unveiled in 1971. It symbolises the bond between Europe and North America, and is inspired by the alliance's flag, which was introduced in 1953.
At NATO's old headquarters, the star was surrounded by the flags of the NATO member countries. When NATO moved to its new headquarters, the star moved across Boulevard Leopold III to its new home on Saturday 28 May 2016.
See also
NATO headquarters
Flag of NATO
References
External links
The NATO Star Sculpture, NATO official website
NATO's Mystery Sculpture, Espionart
Buildings and structures in Brussels
Symbols of NATO
Sculptures in Belgium
Steel sculptures
Star symbols | NATO Star | Mathematics | 153 |
29,449,732 | https://en.wikipedia.org/wiki/Nissan%20VRH%20engine | The Nissan VRH engine family consists of several racing engines built by Nissan Motor Company beginning in the late 1980s. All VRH engines are in a V8 configuration, with either natural aspiration or forced induction. Some VRH engines are loosely based on Nissan's production V8 engine blocks, including the VH and VK engines, while others were designed from the ground up for racing and share no components with production blocks.
The name "VRH" comes from the engines' V configuration ("V"), their purpose as racing engines ("R"), and the fact that all of them have eight cylinders (with "H" being the eighth letter of the Latin alphabet).
History
In 1987, Nissan began work on an engine exclusively for race use; the result was the VEJ30 engine, developed by Yoshikazu Ishikawa. This engine was based on old technology, and was not a success. For 1988, the VEJ30 was improved by Yoshimasa Hayashi and renamed the VRH30. Changes included increasing the displacement to .
This engine was, however, still based on the obsolete VEJ30, and development of the all-new VRH35 was started in parallel with the VRH30. In 1989, the VRH35 appeared as a new development engine and was used in the Nissan R89C.
A 3.0-litre variant of the VRH35Z was also used in the 1998 Courage-Nissan C51 at the 1998 24 Hours of Le Mans. Both C51s failed to finish.
The design of the engine was later sold to McLaren, where it served as the basis of their M838T and M840T engines (which were used in all of McLaren's line-up since the McLaren MP4-12C).
VRH30T
The VRH30T was used in the R88C.
Cylinder Block: Aluminum 90° V8
Aspiration: Twin-Turbo (IHI)
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Power: at 8000 rpm
Torque: at 5500 rpm
VRH35Z
The VRH35Z first appeared in 1990 in the R90C.
Cylinder Block: Aluminum
Aspiration: Twin-Turbo (IHI)
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Compression Ratio: 8.5:1
Power: at 7600 rpm
Torque: at 5600 rpm
Engine Management: ECCS-R-NDIS
Weight:
VRH35L
In 1997, Nissan, working in partnership with Tom Walkinshaw Racing, fielded a VRH35L in the R390 GT1.
Cylinder Block: Aluminum
Aspiration: Twin-Turbo (IHI)
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Compression Ratio: 9.0:1
Power: at 6800 rpm
Torque: at 4400 rpm
Dry weight:
VRH35ADE
The VRH35ADE was used by Infiniti in their Indy race car.
Cylinder Block: Aluminum-alloy block and heads; molybdenum-coated pistons
Aspiration: Naturally Aspirated
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Compression Ratio: 13.8:1
Lubrication System: Multi-stage dry sump
Oil Capacity:
Power: at 10700 rpm
Torque: at 10400 rpm
VRH40ADE
The VRH40ADE was used by Infiniti in their Indy race car.
Cylinder Block: Aluminum-alloy block and heads; molybdenum-coated pistons
Aspiration: Naturally Aspirated
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Compression Ratio: 14.5:1
Lubrication System: Multi-stage dry sump
Oil Capacity:
Power: at 10700 rpm
Torque: at 8500 rpm
VRH34A
The VRH34A is one of two engines used in Nissan's GT500-spec GT-R.
Cylinder Block: Aluminum
Aspiration: Naturally Aspirated
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Power:
Torque: Over
Dry weight: ?
VRH50A
The VRH50A was used in the Nissan R391.
Cylinder Block: Aluminum, Closed Deck
Aspiration: Naturally Aspirated
Valvetrain: DOHC, 4 Valves per Cylinder
Displacement:
Bore x Stroke:
Compression ratio: 14.0:1 (estimated)
Redline: 8000 rpm
Power: at 7200 rpm
Torque: at 6000 rpm
Engine Management: Nissan Electronics/Hitachi HN-1
Weight:
Other VRH engines
The VRH34A and VRH34B are naturally aspirated engines used by Nissan in their GT-R Super GT race car from 2010.
The VRH34A is and produces and over of torque.
The VRH34B is and produces and over of torque.
See also
List of Nissan engines
Nissan VEJ30 engine
Nissan VH engine
Nissan VK engine
Nissan
References
VRH35
World Sportscar Championship engines
V8 engines
Engines by model
Gasoline engines by model
Group C | Nissan VRH engine | Technology | 1,046 |
12,122,477 | https://en.wikipedia.org/wiki/C2H5NO2 | {{DISPLAYTITLE:C2H5NO2}}
The molecular formula C2H5NO2 (molar mass: 75.07 g/mol, exact mass: 75.0320 u) may refer to:
Acetohydroxamic acid
Ethyl nitrite
Glycine
Methyl carbamate
Nitroethane | C2H5NO2 | Chemistry | 72 |
8,997,695 | https://en.wikipedia.org/wiki/Brass%20model | Brass models are scale models typically of railroad equipment, bridges and occasionally of buildings, made from brass or similar alloys. Although die-cast or plastic models have made considerable advances in late 1990s and continue to improve, brass models offer finer details. Brass models, considered to be collector's pieces and museum quality finish, are often used for display purposes rather than model railroad operations. However, these can be made fully operational and many railroaders do use them on their model railroads. They are generally considerably more expensive than other types of models due to limited production quantities and the "handmade" nature of the product itself.
History
In the late 1950s, Japan was known for producing low cost toys and products for export. The first brass model trains were created during the occupation of Japan by Allied forces. Members of allied forces saw some of the models built by various craftsman and procured photos of American steam locomotive prototypes for these artisans to model. These were the early hand-built high quality brass models, built with relatively crude equipment in comparison to tools that became available later. Some people in the model railroad industry took note of what was being done and started importing these models to the United States. The scale of import increased with time. Bill Ryan of PFM (Pacific Fast Mail) was one of the early importers, and to this day the name PFM is synonymous with brass model trains.
The quality of Japanese models continued to improve but with an improving domestic economy, manufacturing cost also increased. Eventually, importers moved their operations to Korea for cost benefits. Although the quality suffered considerably in the early years of this transition, within a few years some very fine brass models were being built.
Thousands of brass model trains have been produced throughout the years. Initially their price was comparable to that of die-cast models, but the detail was far superior. The quality and details of brass models have increased with time along with its price. As of 2014, an articulated HO scale, highly detailed model may retail for as much as US $3000; larger scales can cost even more. The collectibility of late run highly detailed models, along with lower availability, generally keeps the prices high. Historically, the most desirable models have continued to rise in value. Mid-run (1960-1985) models, in particular unpainted models, have appeared to drop in value lately, as they are becoming less desirable in comparison with newer models with much better details. These models still often sell for several times the original suggested retail price.
Glossary
Glossary of brass model train terminology:
Handbuilt Generally refers to the early models made for the GIs that were built entirely by hand. In many ways brass models are still handbuilt to this day.
Crown At first these were very limited runs of the highest quality models imported by PFM. Later the term was used a bit more loosely, though generally only for very high quality models. Other importers used phrases such as 'Ruby' (Gem Models), 'Royale Series' (Custom Brass), or something similar.
Factory Painted A model painted by the builder. Some models were painted in the USA after being imported. Though these paint jobs were commissioned by the importer and are normally high quality, they would be considered custom painted.
Custom Paint This has a broad meaning, as the quality can vary widely; however, it means any model that is painted, but not by the builder.
Pro Paint This term should only be used by professional painters. The quality of a true professional should be very close to that of a factory painted model.
Plated A term for nickel plating; often brass drivers (wheels) are nickel-plated, silver color. At times entire models are nickel-plated (they look like silver).
Wheel Wear This refers to brass showing through on the drivers (wheels). This happens when the engine has been run enough on a track to wear through the nickel plating, and often is a sign of somewhat heavy use of the model.
Drawbar The bar that connects a steam locomotive to the tender. Often needed for a good electrical connection.
Open Frame Motor Used on earlier models, generally up until the early 1970s. You can see the armature, brushes on the sides of the motor.
Can Motor A more desirable motor, as it generally offers more power, and needs less maintenance. The motor is enclosed in a 'can', and the brushes cannot be seen.
Manufacturers
Manufacturers of brass models include:
Bavaria
Boo-Rim Precision
Ajin Precision
Fulgurex
Lemaco
Musashino Model
Active Importers, both in the USA and Europe include:
Precision Scale Models, Inc
Glacier Park Models
The Coach Yard
Union Terminal Imports
North Bank Line
Micro Metakit
Overland Models Inc.
Key Model Imports
Sunset Models, 3rd Rail
Importers that are no longer active include:
Railway Classics
Shoreham Shops
W&R Enterprises
Weinert
Classic Construction Models
Max Gray
Pacific Fast Mail
WestSide Model Company
Ferro Swiss
KTM
NJ International, Custom Brass
E.Suydam & Company
Tenshodo
Von Stetina Artworks
EFC-Loko
TOLOLOKO
See also
Rail transport modelling
Scale models
HO scale
References
External links
For further information please refer to:
The Brass Train Guide Book (http://www.brasstrains.com/Classic/Product/Detail/030010/The-Brass-Train-Guide-Book-Deluxe-Edition)
Brass Model Trains Price & Data Guide Volume 2 (http://www.brasstrains.com/Classic/Product/Detail/030003/Brass-Model-Trains-Price-Data-Guide-Volume-2)
Online Brass Guide LIVE (www.brassguide.com)
Brass Department
Scale modeling
Rail transport modelling | Brass model | Physics | 1,163 |
10,948,856 | https://en.wikipedia.org/wiki/Wildlife%20of%20Gabon | The wildlife of Gabon is composed of its flora and fauna. Gabon is a largely low-lying country with a warm, humid climate. Much of the country is still covered by tropical rainforest and there are also grasslands, savannas, large rivers and coastal lagoons.
Overview
Wildlife includes forest elephants, forest buffalos, various antelope and monkey species, sitatungas, leopards, three species of crocodiles, chimpanzees and gorillas, and several marine turtle species which nest along the coast. As of 2002, there were at least 190 species of mammals.
Fauna
Mammals
Gabon has important populations of many mammals including about 35,000 gorillas, 50,000 forest elephants and 64,000 chimpanzees. About a quarter of Africa's gorillas live in Gabon. Other large mammals include the hippopotamus, forest buffalo, bongo and red river hog. A variety of monkeys occur, including the endemic sun-tailed monkey, and the near-endemic mandrill and white-collared mangabey (here near-endemic meaning most of the individuals of these species are in Gabon, but that they also occur in the neighbouring countries as well). Carnivorous mammals include the leopard, golden cat, and various jackals, mongooses, genets and civets. The last lion was killed in 1996 in the savannahs of the east of the country. The West African manatee is found along coasts and large rivers while the humpback whale breeds offshore.
Birds
There are 604 species of birds throughout the country. None of these are endemic but some such as the Dja River warbler, Verreaux's batis, African river martin and black-chinned weaver are restricted to Central Africa and have only small ranges. The grey-necked picathartes and Loango weaver are classed as vulnerable species by the IUCN.
Reptiles
A variety of snakes are found including the Gaboon viper. Sea turtles breed along the coast, particularly the leatherback turtle.
Flora
There are over 7000 species of native vascular plants in Gabon. About 22% of these are endemic. New species are still being discovered such as the tree Cola lizae which was first described in 1987.
Conservation
Wildlife in Gabon faces a number of threats including logging and poaching. However 11% of the country's area is now protected in a network of 13 national parks established in 2002.
References
Sources
African Bird Club (2008) Birds and Birding in Gabon. Accessed 18 June 2008.
Warne, Sophie (2003) Gabon, São Tomé and Príncipe: The Bradt Travel Guide, Bradt.
External links
"Gabon to Create Huge Park System for Wildlife", National Geographic.
Biota of Gabon
Fauna of Gabon
Flora of Gabon
Gabon | Wildlife of Gabon | Biology | 567 |
39,491,679 | https://en.wikipedia.org/wiki/Transition%20metal%20thiolate%20complex | Transition metal thiolate complexes are metal complexes containing thiolate ligands. Thiolates are ligands that can be classified as soft Lewis bases. Therefore, thiolate ligands coordinate most strongly to metals that behave as soft Lewis acids as opposed to those that behave as hard Lewis acids. Most complexes contain other ligands in addition to thiolate, but many homoleptic complexes are known with only thiolate ligands. The amino acid cysteine has a thiol functional group, consequently many cofactors in proteins and enzymes feature cysteinate-metal cofactors.
Synthesis
Metal thiolate complexes are commonly prepared by reactions of metal complexes with thiols (RSH), thiolates (RS−), and disulfides (R2S2). The salt metathesis reaction route is common. In this method, an alkali metal thiolate is treated with a transition metal halide to produce an alkali metal halide and the metal thiolate complex:
LiSC6H5 + CuI → Cu(SC6H5) + LiI
Lithium tert-butylthiolate reacts with MoCl4 to give the tetrathiolate complex:
MoCl4 + 4 t-BuSLi → Mo(t-BuS)4 + 4 LiCl
Mo(t-BuS)4 is a dark red diamagnetic complex that is sensitive to air and moisture. The molybdenum center has a distorted tetrahedral coordination to four sulfur atoms, with overall D2 symmetry.
Nickelocene and ethanethiol give a dimeric thiolate, one cyclopentadienyl ligand serving as a base:
2 HSC2H5 + 2 Ni(C5H5)2 → [Ni(SC2H5)(C5H5)]2 + 2 C5H6
Regarding their mechanism of formation from thiols, metal thiolate complexes can arise via deprotonation of thiol complexes.
Redox routes
Many thiolate complexes are prepared by redox reactions. Organic disulfides oxidize low valence metals, as illustrated by the oxidation of titanocene dicarbonyl:
Some metal centers are oxidized by thiols, the coproduct being hydrogen gas:
These reactions may proceed by the oxidative addition of the thiol to Fe(0).
Thiols and especially thiolate salts are reducing agents. Consequently, they induce redox reactions with certain transition metals. This phenomenon is illustrated by the synthesis of cuprous thiolates from cupric precursors:
4 HSC6H5 + 2 CuO → 2 Cu(SC6H5) + (C6H5S)2 + 2 H2O
Thiolate clusters of the type [Fe4S4(SR)4]2− occur in iron–sulfur proteins. Synthetic analogues can be prepared by combined redox and salt metathesis reactions:
4 FeCl3 + 6 NaSR + 6 NaSH → Na2[Fe4S4(SR)4] + 10 NaCl + 4 HCl + H2S + R2S2
Structure
Divalent sulfur exhibits bond angles approaching 90°. Such acute angles are also seen in the M-S-C angles of metal thiolates. Having filled p-orbitals of suitable symmetry, thiolates are pi-donor ligands. This property plays a role in the stabilization of Fe(IV) states in the enzyme cytochrome P450.
Reactions
Thiolates are relatively basic ligands, being derived from conjugate acids with pKa's of 6.5 (thiophenol) to 10.5 (butanethiol). Consequently, thiolate ligand often bridge pairs of metals. One example is Fe2(SCH3)2(CO)6. Thiolate ligands, especially when nonbridging, are susceptible to attack by electrophiles including acids, alkylating agents, and oxidants.
Occurrence and applications
Metal thiolate functionality is pervasive in metalloenzymes. Iron-sulfur proteins, blue copper proteins, and the zinc-containing enzyme liver alcohol dehydrogenase feature thiolate ligands. Commonly thiolate is ligand is provided from the cysteine residue. All molybdoproteins feature thiolates in the form of cysteinyl and/or molybdopterin.
References
Thiolates
Biochemistry
Inorganic chemistry
Coordination complexes | Transition metal thiolate complex | Chemistry,Biology | 936 |
30,581,559 | https://en.wikipedia.org/wiki/POSIX%20terminal%20interface | The POSIX terminal interface is the generalized abstraction, comprising both an application programming interface for programs, and a set of behavioural expectations for users of a terminal, as defined by the POSIX standard and the Single Unix Specification. It is a historical development from the terminal interfaces of BSD version 4 and Seventh Edition Unix.
General underlying concepts
Hardware
A multiplicity of I/O devices are regarded as "terminals" in Unix systems. These include:
serial devices connected by a serial port such as printers/teleprinters, teletypewriters, modems supporting remote terminals via dial-up access, and directly connected local terminals
display adapter and keyboard hardware directly incorporated into the system unit, taken together to form a local "console", which may be presented to users and to programs as a single CRT terminal or as multiple virtual terminals
software terminal emulators, such as the xterm, Konsole, GNOME Terminal, and Terminal programs, and network servers such as the rlogin daemon and the SSH daemon, which make use of pseudoterminals
Terminal intelligence and capabilities
Intelligence: terminals are dumb, not intelligent
Unlike its mainframe and minicomputer contemporaries, the original Unix system was developed solely for dumb terminals, and that remains the case today. A terminal is a character-oriented device, comprising streams of characters received from and sent to the device. Although the streams of characters are structured, incorporating control characters, escape codes, and special characters, the I/O protocol is not structured as would be the I/O protocol of smart, or intelligent, terminals. There are no field format specifications. There's no block transmission of entire screens (input forms) of input data.
By contrast mainframes and minicomputers in closed architectures commonly use Block-oriented terminals.
Capabilities: terminfo, termcap, curses, et al.
The "capabilities" of a terminal comprise various dumb terminal features that are above and beyond what is available from a pure teletypewriter, which programs can make use of. They (mainly) comprise escape codes that can be sent to or received from the terminal. The escape codes sent to the terminal perform various functions that a CRT terminal (or software terminal emulator) is capable of that a teletypewriter is not, such as moving the terminal's cursor to positions on the screen, clearing and scrolling all or parts of the screen, turning on and off attached printer devices, programmable function keys, changing display colours and attributes (such as reverse video), and setting display title strings. The escape codes received from the terminal signify things such as function key, arrow key, and other special keystrokes (home key, end key, help key, PgUp key, PgDn key, insert key, delete key, and so forth).
These capabilities are encoded in databases that are configured by a system administrator and accessed from programs via the terminfo library (which supersedes the older termcap library), upon which in turn are built libraries such as the curses and ncurses libraries. Application programs use the terminal capabilities to provide textual user interfaces with windows, dialogue boxes, buttons, labels, input fields, menus, and so forth.
Controlling environment variables: TERM et al.
The particular set of capabilities for the terminal that a (terminal-aware) program's input and output uses is obtained from the database rather than hardwired into programs and libraries, and is controlled by the TERM environment variable (and, optionally for the termcap and terminfo libraries, the TERMCAP and TERMINFO environment variables, respectively). This variable is set by whatever terminal monitor program spawns the programs that then use that terminal for its input and output, or sometimes explicitly. For example:
The getty program (or equivalent) sets the TERM environment variable according to a system database (variously inittab or the configuration files for the ttymon or launchd programs) defining what local terminals are attached to what serial ports and what terminal types are provided by local virtual terminals or the local system console.
A dial-up user on a remote terminal is not using the type of terminal that the system commonly expects on that dial-up line, and so manually sets the TERM environment variable immediately after login to the correct type. (More usually, the terminal type set by the getty program for the dial-up line, that the system administrator has determined to be used most often by dial-up users with remote terminals, matches the one used by the dial-up user and that user has no need to override the terminal type.)
The SSH server daemon (or equivalent such as the rlogin daemon) sets the TERM environment variable to the same terminal type as the SSH client.
The software terminal emulator, using a pseudoterminal, sets the TERM environment variable to specify the type of terminal that it is emulating. Emulated terminals often do not exactly match real terminal hardware, and terminal emulators have type names dedicated for their use. The xterm program (by default) sets xterm as the terminal type, for example. The GNU Screen program sets screen as the terminal type.
Job control
Terminals provide job control facilities. Interactively, the user at the terminal can send control characters that suspend the currently running job, reverting to the interactive job control shell that spawned the job, and can run commands that place jobs in the "background" or that switch another, background, job into the foreground (unsuspending it if necessary).
Line disciplines
Strictly speaking, in Unixes a terminal device comprises the underlying tty device driver, responsible for the physical control of the device hardware via I/O instructions and handling device interrupt requests for character input and output, and the line discipline. A line discipline is independent of the actual device hardware, and the same line discipline can be used for a terminal concentrator device responsible for multiple controlling terminals as for a pseudoterminal. In fact, the line discipline (or, in the case of BSD, AIX, and other systems, line disciplines) are the same across all terminal devices. It is the line discipline that is responsible for local echo, line editing, processing of input modes, processing of output modes, and character mapping. All these things are independent of the actual hardware, dealing as they do in the simple abstractions provided by tty device drivers: transmit a character, receive a character, set various hardware states.
In Seventh Edition Unix, BSD systems and derivatives including macOS, and Linux, each terminal device can be switched amongst multiple line disciplines. In the AT&T STREAMS system, line disciplines are STREAMS modules that may be pushed onto and popped off a STREAMS I/O stack.
History
The POSIX terminal interface is derived from the terminal interfaces of various Unix systems.
Early Unixes: Seventh Edition Unix
The terminal interface provided by Unix 32V and Seventh Edition Unix, and also presented by BSD version 4 as the old terminal driver, was a simple one, largely geared towards teletypewriters as terminals. Input was entered a line at a time, with the terminal driver in the operating system (and not the terminals themselves) providing simple line editing capabilities. A buffer was maintained by the kernel in which editing took place. Applications reading terminal input would receive the contents of the buffer only when the key was pressed on the terminal to end line editing. The key sent from the terminal to the system would erase ("kill") the entire current contents of the editing buffer, and would be normally displayed as an '' symbol followed by a newline sequence to move the print position to a fresh blank line. The key sent from the terminal to the system would erase the last character from the end of the editing buffer, and would be normally displayed as an '' symbol, which users would have to recognize as denoting a "rubout" of the preceding character (teletypewriters not being physically capable of erasing characters once they have been printed on the paper).
From a programming point of view, a terminal device had transmit and receive baud rates, "erase" and "kill" characters (that performed line editing, as explained), "interrupt" and "quit" characters (generating signals to all of the processes for which the terminal was a controlling terminal), "start" and "stop" characters (used for modem flow control), an "end of file" character (acting like a carriage return except discarded from the buffer by the read() system call and therefore potentially causing a zero-length result to be returned) and various basic mode flags determining whether local echo was emulated by the kernel's terminal driver, whether modem flow control was enabled, the lengths of various output delays, mapping for the carriage return character, and the three input modes.
The three input modes were:
line mode (also called "cooked" mode)
In line mode the line discipline performs all line editing functions and recognizes the "interrupt" and "quit" control characters and transforms them into signals sent to processes. Applications programs reading from the terminal receive entire lines, after line editing has been completed by the user pressing return.
cbreak mode
cbreak mode is one of two character-at-a-time modes. (Stephen R. Bourne jokingly referred to it as a "half-cooked" and therefore "rare" mode.) The line discipline performs no line editing, and the control sequences for line editing functions are treated as normal character input. Applications programs reading from the terminal receive characters immediately, as soon as they are available in the input queue to be read. However, the "interrupt" and "quit" control characters, as well as modem flow control characters, are still handled specially and stripped from the input stream.
raw moderaw mode is the other of the two character-at-a-time modes. The line discipline performs no line editing, and the control sequences for both line editing functions and the various special characters ("interrupt", "quit", and flow control) are treated as normal character input. Applications programs reading from the terminal receive characters immediately, and receive the entire character stream unaltered, just as it came from the terminal device itself.
The programmatic interface for querying and modifying all of these modes and control characters was the ioctl() system call. (This replaced the stty() and gtty() system calls of Sixth Edition Unix.) Although the "erase" and "kill" characters were modifiable from their defaults of and , for many years they were the pre-set defaults in the terminal device drivers, and on many Unix systems, which only altered terminal device settings as part of the login process, in system login scripts that ran after the user had entered username and password, any mistakes at the login and password prompts had to be corrected using the historical editing key characters inherited from teletypewriter terminals.
BSD: the advent of job control
With the BSD Unixes came job control, and a new terminal driver with extended capabilities. These extensions comprised additional (again programmatically modifiable) special characters:
The "suspend" and "delayed suspend" characters (by default and — ASCII SUB and EM) caused the generation of a new SIGTSTP signal to processes in the terminal's controlling process group.
The "word erase", "literal next", and "reprint" characters (by default , , and — ASCII ETB, SYN, and DC2) performed additional line editing functions. "word erase" erased the last word at the end of the line editing buffer. "literal next" allowed any special character to be entered into the line editing buffer (a function available, somewhat inconveniently, in Seventh Edition Unix via the backslash character). "reprint" caused the line discipline to reprint the current contents of the line editing buffer on a new line (useful for when another, background, process had generated output that had intermingled with line editing).
The programmatic interface for querying and modifying all of these extra modes and control characters was still the ioctl() system call, which its creators described as a "rather cluttered interface". All of the original Seventh Edition Unix functionality was retained, and the new functionality was added via additional ioctl() operation codes, resulting in a programmatic interface that had clearly grown, and that presented some duplication of functionality.
System III and System V
System III introduced a new programming interface that combined Seventh Edition's separate ioctl() operations to get and set flags and to get and set control characters into calls that used a termio structure to hold both flags and control characters and that could get them in a single operation and set them in another single operation. It also split some of the flags from the Seventh Edition interface into multiple separate flags, and added some additional capabilities, although it did not support job control or the cooked-mode enhancements of 4BSD. For example, it replaced the "cooked", "cbreak", and "raw" modes of Seventh Edition with different abstractions. The recognition of signal-generating characters is independent of input mode, and there are only the two input modes: canonical and non-canonical. (This allows a terminal input mode not present in Seventh Edition and BSD: canonical mode with signal generation disabled.)
System III's successors, including System V, used the same interface.
POSIX: Consolidation and abstraction
One of the major problems that the POSIX standard addressed with its definition of a general terminal interface was the plethora of programmatic interfaces. Although by the time of the standard the behaviour of terminals was fairly uniform from system to system, most Unixes having adopted the notions of line disciplines and the BSD job control capabilities, the programmatic interface to terminals via the ioctl() system call was a mess. Different Unixes supplied different ioctl() operations, with different (symbolic) names, and different flags. Portable source code had to contain a significant amount of conditional compilation to accommodate the differences across software platforms, even though they were all notionally Unix.
The POSIX standard replaces the ioctl() system entirely, with a set of library functions (which, of course, may be implemented under the covers via platform-specific ioctl() operations) with standardized names and parameters. The termio data structure of System V Unix was used as a template for the POSIX termios data structure, whose fields were largely unchanged except that they now used alias data types for specifying the fields, allowing them to be easily ported across multiple processor architectures by implementors, rather than explicitly requiring the unsigned short and char data types of the C and C++ programming languages (which might be inconvenient sizes on some processor architectures).
POSIX also introduced support for job control, with the termios structure containing suspend and delayed-suspend characters in addition to the control characters supported by System III and System V. It did not add any of the cooked-mode extensions from BSD, although SunOS 4.x, System V Release 4, Solaris, HP-UX, AIX, newer BSDs, macOS, and Linux have implemented them as extensions to termios.
What the standard defines
Controlling terminals and process groups
Each process in the system has either a single controlling terminal, or no controlling terminal at all. A process inherits its controlling terminal from its parent, and the only operations upon a process are acquiring a controlling terminal, by a process that has no controlling terminal, and relinquishing it, by a process that has a controlling terminal.
No portable way of acquiring a controlling terminal is defined, the method being implementation defined. The standard defines the O_NOCTTY flag for the open() system call, which is the way of preventing what is otherwise the conventional way of acquiring a controlling terminal (a process with no controlling terminal open()s a terminal device file that isn't already the controlling terminal for some other process, without specifying the O_NOCTTY flag) but leaves its conventional semantics optional.
Each process also is a member of a process group. Each terminal device records a process group that is termed its foreground process group. The process groups control terminal access and signal delivery. Signals generated at the terminal are sent to all processes that are members of the terminal's foreground process group. read() and write() I/O operations on a terminal by a process that is not a member of the terminal's foreground process group will and may optionally (respectively) cause signals (SIGTTIN and SIGTTOU respectively) to be sent to the invoking process. Various terminal-mode-altering library functions have the same behaviour as write(), except that they always generate the signals, even if that functionality is turned off for write() itself.
The termios data structure
The data structure used by all of the terminal library calls is the termios structure, whose C and C++ programming language definition is as follows:struct termios {
tcflag_t c_iflag ; // Input modes
tcflag_t c_oflag ; // Output modes
tcflag_t c_cflag ; // Control modes
tcflag_t c_lflag ; // Local modes
cc_t c_cc[NCCS] ; // Control characters
} ;
The order of the fields within the termios structure is not defined, and implementations are allowed to add non-standard fields. Indeed, implementations have to add non-standard fields for recording input and output baud rates. These are recorded in the structure, in an implementation-defined form, and accessed via accessor functions, rather than by direct manipulation of the field values, as is the case for the standardized structure fields.
The data type aliases tcflag_t and cc_t, as well as the symbolic constant NCCS and symbolic constants for the various mode flags, control character names, and baud rates, are all defined in a standard header termios.h. (This is not to be confused with the similarly named header termio.h from System III and System V, which defines a similar termio structure and a lot of similarly named symbolic constants. This interface is specific to System III and System V, and code that uses it will not necessarily be portable to other systems.)
The structure's fields are (in summary, for details see the main article):
c_iflaginput mode flags for controlling input parity, input newline translation, modem flow control, 8-bit cleanliness, and response to a (serial port's) "break" condition
c_oflagoutput mode flags for controlling implementation-defined output postprocessing, output newline translation, and output delays after various control characters have been sent
c_cflagterminal hardware control flags for controlling the actual terminal device rather than the line discipline: the number of bits in a character, parity type, hangup control, and serial line flow control
c_lflaglocal control flags for controlling the line discipline rather than the terminal hardware: canonical mode, echo modes, signal-generation character recognition and handling, and enabling the generation of the SIGTTOU signal by the write() system call
The library functions are (in summary, for details see the main article):
tcgetattr()query a terminal device's current attribute settings into a termios structure
tcsetattr()set a terminal device's current attribute settings from a termios structure, optionally waiting for queued output to drain and flushing queued input
cfgetispeed()query the input baud rate from the implementation-defined fields in a termios structure
cfgetospeed()query the output baud rate from the implementation-defined fields in a termios structure
cfsetispeed()set the input baud rate in the implementation-defined fields in a termios structure
cfsetospeed()set the output baud rate in the implementation-defined fields in a termios structure
tcsendbreak()send a modem "break" signal on a serial device terminal
tcdrain()wait for queued output to drain
tcflush()discard queued input
tcflow()change flow control
tcgetpgrp()query the terminal's foreground process group
tcsetpgrp()set the terminal's foreground process group
Special characters
The c_cc[] array member of the termios data structure specifies all of the (programmatically modifiable) special characters. The indexes into the array are symbolic constants, one for each special character type, as in the table at right. (Two further entries in the array are relevant to non-canonical mode input processing and are discussed below.)
Non-programmatically modifiable special characters are linefeed (ASCII LF) and carriage return (ASCII CR).
Input processing
Input processing determines the behaviour of the read() system call on a terminal device and the line editing and signal-generation characteristics of the line discipline. Unlike the case of Seventh Edition Unix and BSD version 4, and like the case of System III and System V, line editing operates in one of just two modes: canonical mode and non-canonical mode. The basic difference between them is when, from the point of view of the blocking/non-blocking requirements of the read() system call (specified with the O_NONBLOCK flag on the file descriptor via open() or fcntl()), data "are available for reading".
Canonical mode processing
In canonical mode, data are accumulated in a line editing buffer, and do not become "available for reading" until line editing has been terminated by the user (at the terminal) sending a line delimiter character. Line delimiter characters are special characters, and they are end of file, end of line, and linefeed (ASCII LF). The former two are settable programmatically, whilst the latter is fixed. The latter two are included in the line editing buffer, whilst the former one is not.
More strictly, zero or more lines are accumulated in the line editing buffer, separated by line delimiters (which may or may not be discarded once read() comes around to reading them), and line editing operates upon the part of the line editing buffer that follows the last (if any) line delimiter in the buffer. So, for example, the "erase" character (whatever that has been programmed to be) will erase the last character in the line buffer only up to (but not including) a preceding line delimiter.
Non-canonical mode processing
In non-canonical mode, data are accumulated in a buffer (which may or may not be the line editing buffer — some implementations having separate "processed input" and "raw input" queues) and become "available for reading" according to the values of two input control parameters, the c_cc[MIN] and c_cc[TIME] members of the termios data structure. Both are unsigned quantities (because cc_t is required to be an alias for an unsigned type). The former specifies a minimum number of characters, and the latter specifies a timeout in tenths of a second. There are four possibilities:
c_cc[TIME] and c_cc[MIN] are both zero
In this case, the data in the buffer are "available for reading" immediately, and read() returns immediately with whatever data are in the buffer (potentially returning zero if there are zero data available).
c_cc[TIME] is non-zero and c_cc[MIN] is zero
In this case, the data in the buffer are "available for reading" after the specified timeout has elapsed, the timer being triggered by the start of the read() system call, or if a single character is received. In other words, read() waits for a maximum specified total time, and may return zero data, and returns any data as soon as they are received.
c_cc[TIME] is zero and c_cc[MIN] is non-zero
In this case, the data in the buffer are "available for reading" after the specified number of characters have been received in the buffer. In other words, read() waits for a minimum amount of data (which may be larger than what the caller is prepared to read in the system call), will not return zero data, and may wait indefinitely.
c_cc[TIME] and c_cc[MIN] are both non-zero
In this case, the data in the buffer are "available for reading" after the specified number of characters have been received in the buffer or the timeout has expired since the last character was entered. There is no timeout for the very first character. In other words, read() waits for a minimum amount of data (which may be larger than what the caller is prepared to read in the system call), will not return zero data, may wait indefinitely, but won't wait longer than the specified timeout if at least one character is in the buffer to be read.
Output processing
Output processing is largely unchanged from its System III/System V roots. Output mode control flags determine various options:
Carriage returns may be inserted before each linefeed character, to translate Unix newline semantics to the ASCII semantics that many terminals expect.
Terminals may be given time to exercise various control codes that would (on a teletypewriter or similar) result in physical movements of the carriage that may take significant (from the computer's point of view) amounts of time, such as backspaces, horizontal tabs, carriage returns, form feeds, and line feeds.
Notes
Sources
Further reading
Computer terminals
POSIX | POSIX terminal interface | Technology | 5,352 |
3,701,507 | https://en.wikipedia.org/wiki/Mecanum%20wheel | A Mecanum wheel is an omnidirectional wheel design for a land-based vehicle to move in any direction. It is sometimes called the Swedish wheel or Ilon wheel after its inventor, Bengt Erland Ilon (1923–2008), who conceived of the concept while working as an engineer with the Swedish company Mecanum AB, and patented it in the United States on November 13, 1972.
It consists of a series of rubberized external rollers set at a 45° angle to the wheel. Each wheel is independently-driven, and the direction of travel is dependent on the interaction between the directions each wheel is driven in relative to the others.
Uses include forklifts which require very tight maneuvering, autonomous robots, and wheelchairs.
Design
The Mecanum wheel is a form of tireless wheel, with a series of rubberized external rollers obliquely attached to the whole circumference of its rim. These rollers typically each have an axis of rotation at 45° to the wheel plane and at 45° to the axle line. Each Mecanum wheel is an independent non-steering drive wheel with its own powertrain, and when spinning generates a propelling force perpendicular to the roller axle, which can be vectored into a longitudinal and a transverse component in relation to the vehicle.
The typical Mecanum design is a four-wheel configuration with an alternating with left- and right-handed rollers whose axles at the top of the wheel are parallel to the diagonal of the vehicle frame (and hence perpendicular to the diagonal when at where the bottom of the wheel contacts the ground). In such a way, each wheel will generate a thrust roughly parallel to the corresponding frame diagonal. By varying the rotational speed and direction of each wheel, the summation of the force vectors from each of the wheels will create both linear motions and/or rotations of the vehicle, allowing it to maneuver around with minimal need for space. For example:
Running all four wheels in the same direction at the same speed will result in a forward/backward movement, as the longitudinal force vectors add up but the transverse vectors cancel each other out;
Running (all at the same speed) both wheels on one side in one direction while the other side in the opposite direction, will result in a stationary rotation of the vehicle, as the transverse vectors cancel out but the longitudinal vectors couple to generate a torque around the central vertical axis of the vehicle;
Running (all at the same speed) the diagonal wheels in one direction while the other diagonal in the opposite direction will result in a sideways movement, as the transverse vectors add up but the longitudinal vectors cancel out.
A mix of differential wheel motions will allow for vehicle motion in almost any direction with any rotation.
Uses
The US Navy bought the patent from Ilon and put researchers to work on it in the 1980s in Panama City, Florida. The US Navy has used it for transporting items around ships. In 1997, Airtrax Incorporated and several other companies each paid the US Navy $2,500 for rights to the technology, including old drawings of how the motors and controllers worked, to build an omnidirectional forklift truck that could maneuver in tight spaces such as the deck of an aircraft carrier. These vehicles are now in production.
Tracked vehicles and skid steer vehicles utilize similar methods for turning. However, these vehicles typically drag across the ground while turning and may do considerable damage to a soft or fragile surface. The high friction against the ground while turning also requires high-torque engines to overcome the friction. By comparison, the design of the Mecanum wheel allows for in-place rotation with minimal ground friction and low torque.
Youth robotics competitions such as FIRST Tech Challenge and VEX Robotics often see the use of Mecanum wheels by participating teams. The omnnidirectional movement provided by the Mecanum design can give robots additional maneuverability and flexibility for tackling the competition's goals and traversing the terrain when the configuration of the competition's playing field is suitable for the design. Many teams have adapted Mecanum wheels from suppliers such as Nexus and GoBilda, or manufacture their own.
The CMU URANUS Mobile Robot was the first mobile robot with Mecanum wheels built in 1985 and was used for two decades for autonomous navigation research. CMU's "Tessellator" robot, designed in 1992 for servicing Space Shuttle tiles, also used Mecanum wheels.
A wheelchair using Mecanum wheels was presented at the 2006 EVER Monaco.
See also
References
External links
Airtrax video
Orlando Business Journal article Omnics' wheel of fortune rolls into production by Chad Eric Watt, 31 May 2002.
The Wall Street Journal online Make It by Paulette Thomas, 9 May 2005.
Segway RMP Photos of a 2008 Segway robot with Mecanum wheels.
Video of a wheel chair with Mecanum wheels (WMV)
Swedish inventions
Mechanisms (engineering)
Wheels
1973 introductions | Mecanum wheel | Engineering | 1,014 |
48,724,986 | https://en.wikipedia.org/wiki/Uromycladium%20tepperianum | Uromycladium tepperianum is a rust fungus that infects over 100 species of Acacia and related genera including Paraserianthes in Australia, south-east Asia, the south Pacific and New Zealand. The acacia gall rust fungus species Uromycladium tepperianum has been introduced to South Africa as a biological control on the invasive Australian shrub Acacia saligna.
Uromycladium tepperianum is differentiated from other species of Uromycladium by the presence of three one-celled fertile teliospores on the pedicel.
Distribution
The fungus is present in Australia, Philippines, Malaysia, Indonesia, Timor Leste, and New Zealand. It was introduced deliberately to South Africa for biological control.
Ecology
The galls of Uromycladium tepperianum have been reported to be used by moths in the families Gracillariidae, Tortricidae, Tineidae, Pyralidae, and Stathmopodidae as food sources and domatium for their larvae in Australia. Specifically in the family Gracillariidae the species Polysoma eumetalla and Conopomorpha heliopla are found feeding on the surface of various species of acacia rust galls. Erechthias mystacinella and Opogona comptella moth larvae from the family Tineidae have been reported to live and feed on the inside of U. tepperianum galls.
References
Fungi described in 1889
Fungi of Australia
Fungi of Asia
Fungi of Africa
Fungi of New Zealand
Pucciniales
Taxa named by Pier Andrea Saccardo
Fungus species | Uromycladium tepperianum | Biology | 332 |
748,931 | https://en.wikipedia.org/wiki/Slide%20show | A slide show, or slideshow, is a presentation of a series of still images (slides) on a projection screen or electronic display device, typically in a prearranged sequence. The changes may be automatic and at regular intervals or they may be manually controlled by a presenter or the viewer. Slide shows originally consisted of a series of individual photographic slides projected onto a screen with a slide projector, as opposed to the video or computer-based visual equivalent, in which the slides are not individual physical objects.
A slide show may be a presentation of images purely for their own visual interest or artistic value, sometimes unaccompanied by description or text, or it may be used to clarify or reinforce information, ideas, comments, solutions or suggestions which are presented verbally. Slide shows are sometimes still conducted by a presenter using an apparatus such as a carousel slide projector or an overhead projector, but now the use of an electronic video display device and a computer running presentation software is typical.
History
Slide shows had their beginnings in the 1600s, when hand-painted images on glass were first projected onto a wall with a "magic lantern". By the late 1700s, showmen were using magic lanterns to thrill audiences with seemingly supernatural apparitions in a popular form of entertainment called a phantasmagoria. Sunlight, candles and oil lamps were the only available light sources. The development of new, much brighter artificial light sources opened up a world of practical applications for image projection. In the 1800s, a series of hand-painted glass "lantern slides" was sometimes projected to illustrate story-telling or a lecture. Widespread and varied uses for amusement and education evolved throughout the century. By 1900, photographic images on glass had replaced hand-painted images, but the black-and-white photographs were sometimes hand-colored with transparent dyes. The production of lantern slides had become a considerable industry, with dimensions standardized at 3.25 inches high by 4 inches wide in the US and 3.25 inches square in the UK and much of Europe.
"Magic lantern shows" also served as a form of home entertainment and were especially popular with children. They continued to have a place among commercial public amusements even after the coming of projected "moving pictures". Between films, early movie theaters often featured "illustrated songs", which were community sing-alongs with the lyrics and illustrations provided by a series of projected lantern slides. Theaters also used their lanterns to project advertising slides and messages such as "Ladies, kindly remove your hats".
After 35 mm Kodachrome color film was introduced in 1936, a new standard 2×2 inch (5×5 cm) miniature lantern slide format was created to better suit the very small transparencies the film produced. In advertising, the antique "magic lantern" terminology was streamlined, so that the framed pieces of film were simply "slides" and the lantern used to project them was a "slide projector".
Home slide shows were a relatively common phenomenon in middle-class American homes during the 1950s and 1960s.
An image on 35 mm film mounted in a 2×2 inch (5×5 cm) metal, card or plastic frame is still by far the most common photographic slide format.
Uses
A well-organized slide show allows a presenter to fit visual images to an oral presentation. The old adage "A picture is worth a thousand words" holds true, in that a single image can save a presenter from speaking a paragraph of descriptive details. As with any public speaking or lecturing, a certain amount of talent, experience, and rehearsal is required to make a successful slide show presentation.
Presentation software is most commonly used in the business world, where millions of presentations are created daily. Another very important area where it is used is for instructional purposes, usually with the intention of creating a dynamic, audiovisual presentation. The relevant points to the entire presentation are put on slides, and accompany a spoken monologue.
Slide shows have artistic uses as well, such as being used as a screensaver, or to provide dynamic imagery for a museum presentation, for example, or in installation art. David Byrne, among others, has created PowerPoint art. Slide shows have also been used for creating animations and games.
In art
Since the late 1960s, visual artists have used slide shows in museums and galleries as a device, either for presenting specific information about an action or research or as a phenomenological form in itself. According to the introduction of Slide Show, an exhibition organized at the Baltimore Museum of Art: “Through the simple technology of the slide projector and 35 mm color transparency, artists discovered a tool that enabled the transformation of space through the magnification of projected pictures, texts, and images.” Although some artists have not necessarily used 35 mm or color slides, and some, such as Robert Barry, have even abandoned images for texts, 35 mm color film slides are most commonly used. The images are sometimes accompanied by written text, either in the same slide or as an intertitle. Some artists, such as James Coleman and Robert Smithson, have used a voice-over with their slide presentations.
Slide shows have also been used by artists who use other media such as painting and sculpture to present their work publicly. In recent years there has been a growing use of the slide show by a younger generation of artists. The non-profit organization Slideluck Potshow holds slide show events globally, featuring works by amateur and professional artists, photographers, and gallerists. Participants in the event bring food, potluck style, and have a social dinner before the slide show begins.
Other known artists who have used slide shows in their work include Bas Jan Ader, Francis Alys, Jan Dibbets, Dan Graham, Rodney Graham, Nan Goldin, Louise Lawler, Ana Mendieta, Jonathan Monk, Dennis Oppenheim, Allan Sekula, Carey Young and Krzysztof Wodiczko.
Digital
Digital photo slide shows can be custom-made for clients from their photos, music, wedding invitations, birth announcements, or virtually any other scannable documents. Some producers call the resulting DVDs the new photomontage. Slide shows can be created not only on DVD, but also in HD video formats and as executable computer files. Photo slide show software has made it easy to create electronic digital slide shows, eliminating the need for expensive color reversal film and requiring only a digital camera and computer.
Photo slide show software often provides more options than simply showing the pictures. It is possible to add transitions, pan and zoom effects, video clips, background music, narration, captions, etc. By using computer software one therefore has the ability to enhance the presentation in a way that is not otherwise practical. The finished slide show can then be burned to a DVD, for use as a gift or for archiving, and later viewed using an ordinary DVD player.
Web-based slide show
A web-based slide show is a slide show which can be played (viewed or presented) using a web browser. Some web based slide shows are generated from presentation software and may be difficult to change (usually unintentionally so). Others offer templates allowing the slide show to be easily edited and changed.
Compared to a fully fledged presentation program the web based slide shows are usually limited in features.
A web-based slide show is typically generated to or authored in HTML, JavaScript and CSS code (files).
See also
Photo slideshow software
PowerPoint animation
Presentation software
Multi-image
Slide-tape
Filmstrip
LCD projector
Wireless clicker
References
Photography
Presentation | Slide show | Technology | 1,544 |
58,429,169 | https://en.wikipedia.org/wiki/Tim%20Peters%20%28software%20engineer%29 | Tim Peters is a software developer who is known for creating the Timsort hybrid sorting algorithm and for his major contributions to the Python programming language and its original CPython implementation. A pre-1.0 CPython user, he was among the group of early adopters who contributed to the detailed design of the language in its early stages.
He later created the Timsort algorithm (based on earlier work on the use of "galloping" search) which is used in Python since version 2.3 (since version 3.11 using the Powersort merge policy instead of Timsort's original merge policy), as well as in other widely used computing platforms, including the V8 JavaScript engine powering the Google Chrome and Chromium web browsers, as well as Node.js. He has also contributed the doctest and timeit modules to the Python standard library.
Peters also wrote the Zen of Python, intended as a statement of Python's design philosophy, which was incorporated into the official Python literature as Python Enhancement Proposal 20 and in the Python interpreter as an easter egg. He contributed the chapter on algorithms to the Python Cookbook. From 2001 to 2014 he was active as a member of the Python Software Foundation's board of directors. Peters was an influential contributor to Python mailing lists. He is also a highly ranked contributor to Stack Overflow, mostly for answers relating to Python.
Peters' past employers include Kendall Square Research.
Tim Peters was granted the Python Software Foundation's Distinguished Service Award for 2017.
See also
History of Python
References/Notes and references
External links
PyCon 2006 interview with Tim Peters
Stack Overflow user page
PythonLabs.com
Python (programming language) people
American computer programmers
Free software programmers
Living people
Place of birth missing (living people)
Year of birth missing (living people) | Tim Peters (software engineer) | Technology | 373 |
5,864,407 | https://en.wikipedia.org/wiki/Jervine | Jervine is a steroidal alkaloid with molecular formula C27H39NO3 which is derived from the plant genus Veratrum. Similar to cyclopamine, which also occurs in the genus Veratrum, it is a teratogen implicated in birth defects when consumed by animals during a certain period of their gestation.
Physiological effects
Jervine is a potent teratogen causing birth defects in vertebrates. In severe cases it can cause cyclopia and holoprosencephaly.
Mechanism of action
Jervine's biological activity is mediated via its interaction with the 7 pass trans membrane protein smoothened. Jervine binds with and inhibits smoothened, which is an integral part of the hedgehog signaling pathways. With smoothened inhibited, the GLI1 transcription cannot be activated and hedgehog target genes cannot be transcribed.
References
Teratogens
Jervines
Spiro compounds
Secondary alcohols
Ketones
Oxygen heterocycles
Nitrogen heterocycles
Plant toxins | Jervine | Chemistry | 209 |
898,732 | https://en.wikipedia.org/wiki/Tensiometer%20%28surface%20tension%29 | In surface science, a tensiometer is a measuring instrument used to measure the surface tension () of liquids or surfaces. Tensiometers are used in research and development laboratories to determine the surface tension of liquids like coatings, lacquers or adhesives. A further application field of tensiometers is the monitoring of industrial production processes like parts cleaning or electroplating.
Types
Goniometer/Tensiometer
Surface scientists commonly use an optical goniometer/tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods. A drop is produced and captured using a CCD camera. The drop profile is subsequently extracted, and sophisticated software routines then fit the theoretical Young-Laplace equation to the experimental drop profile. The surface tension can then be calculated from the fitted parameters. Unlike other methods, this technique requires only a small amount of liquid making it suitable for measuring interfacial tensions of expensive liquids.
Du Noüy ring tensiometer
This type of tensiometer uses a platinum ring which is submersed in a liquid. As the ring is pulled out of the liquid, the force required is precisely measured in order to determine the surface tension of the liquid.
The method is well-established as shown by a number of international standards on it such as ASTM D971. This method is widely used for interfacial tension measurement between two liquids but care should be taken to make sure to keep the platinum ring undeformed.
Wilhelmy plate tensiometer
The Wilhelmy plate tensiometer requires a plate to make contact with the liquid surface. It is widely considered the simplest and most accurate method for surface tension measurement. Due to a large wetted length of the platinum plate, the surface tension reading is typically very stable compared to alternative methods. As an additional benefit, the Wilhelmy plate can also be made from paper for disposable use. For interfacial tension measurements, buoyancy of the probe needs to be taken into account which complicates the measurement.
Du Noüy-Padday method
This method uses a rod which is lowered into a test liquid. The rod is then pulled out of the liquid and the force required to pull the rod is precisely measured. The method isn't standardized but is sometimes used. The Du Noüy-Padday rod pull tensiometer will take measurements quickly and will work with liquids with a wide range of viscosities. Interfacial tensions cannot be measured.
Bubble pressure tensiometer
Due to internal attractive forces of a liquid, air bubbles within the liquids are compressed. The resulting pressure (bubble pressure) rises at a decreasing bubble radius. The bubble pressure method makes use of this bubble pressure which is higher than in the surrounding environment (water). A gas stream is pumped into a capillary that is immersed in a fluid. The resulting bubble at the end of the capillary tip continually becomes bigger in surface; thereby, the bubble radius is decreasing.
The pressure rises to a maximum level. At this point the bubble has achieved its smallest radius (the capillary radius) and begins to form a hemisphere. Beyond this point the bubble quickly increases in size and soon bursts, tearing away from the capillary, thereby allowing a new bubble to develop at the capillary tip. It is during this process that a characteristic pressure pattern develops (see picture), which is evaluated for determining the surface tension.
Because of the easy handling and the low cleaning effort of the capillary, bubble pressure tensiometers are a common alternative for monitoring the detergent concentration in cleaning or electroplating processes.
See also
Stalagmometric method
Surface tension
Young-Laplace equation
Capillary action
Piezometer
Pierre Lecomte du Nouy
Interfacial rheology
References
External links
Surface science
Laboratory equipment | Tensiometer (surface tension) | Physics,Chemistry,Materials_science | 788 |
24,376,770 | https://en.wikipedia.org/wiki/Molecular%20Membrane%20Biology | Molecular Membrane Biology is a peer-reviewed scientific journal that publishes review articles of biomembranes at the molecular level. It is published by Taylor & Francis. The editor-in-chief is Vincent Postis.
External links
Academic journals established in 1978
Molecular and cellular biology journals
Taylor & Francis academic journals
English-language journals
Annual journals | Molecular Membrane Biology | Chemistry | 69 |
11,144,474 | https://en.wikipedia.org/wiki/Light-gated%20ion%20channel | Light-gated ion channels are a family of ion channels regulated by electromagnetic radiation. Other gating mechanisms for ion channels include voltage-gated ion channels, ligand-gated ion channels, mechanosensitive ion channels, and temperature-gated ion channels. Most light-gated ion channels have been synthesized in the laboratory for study, although two naturally occurring examples, channelrhodopsin and anion-conducting channelrhodopsin, are currently known. Photoreceptor proteins, which act in a similar manner to light-gated ion channels, are generally classified instead as G protein-coupled receptors.
Mechanism
Light-gated ion channels function in a similar manner to other gated ion channels. Such transmembrane proteins form pores through lipid bilayers to facilitate the passage of ions. These ions move from one side of the membrane to another under the influence of an electrochemical gradient. When exposed to a stimulus, a conformational change occurs in the transmembrane region of the protein to open or close the ion channel. In the specific case of light-gated ion channels, the transmembrane proteins are usually coupled with a smaller molecule that acts as a photoswitch, whereby photons bind to the switching molecule, to then alter the conformation of the proteins, so that the pore changes from a closed state to an open state, or vice versa, thereby increasing or decreasing ion conductance. Retinal is a good example of a molecular photoswitch and is found in the naturally occurring channelrhodopsins.
Synthetic isoforms
Once channelrhosopsin had been identified and characterized, the channel's ion selectivity was modified in order to control membrane potential through optogenetic control. Directed mutations of the channel changed the charges lining the pore, resulting in a pore which instead excluded cations in favor of anions.
Other types of gated ion channels, ligand-gated and voltage-gated, have been synthesized with a light-gated component in an attempt to better understand their nature and properties. By the addition of a light-gated section, the kinetics and mechanisms of operation can be studied in depth. For example, the addition of a light-gated component allows for the introduction of many highly similar ligands to be introduced to the binding site of a ligand-gated ion channel to assist in the determination of the mechanism.
Such ion channels have been modified by binding a photoswitch to confer photosensitivity on the ion channel. This is done through careful selection of a tether which can lengthen or shorten through photoisomerization. One side of the tether is bound to the ion channel protein and the other end of the tether is bound to a blocking group, which has a high binding affinity for an exposed portion of the pore. When the tether is lengthened, it allows the blocking section to bind to the pore and prevent ionic current. When the tether is shortened, it disrupts this obstruction and opens the pore. Kinetic studies have demonstrated that fine temporal and spatial control can be achieved in this manner.
Azobenzene is a common choice for the functional portion of a tether for synthetically-developed light-gated ion channels because of its well documented length change as either cis or trans isomers, as well as the excitation wavelength needed to induce photoisomerization. Azobenzene converts to its longer trans-isomer at a wavelength of λ=500 nm and to its cis-isomer at λ=380 nm.
In 1980, the first ion channel to be adapted for study with a light-gated mechanism was the nicotinic acetylcholine receptor. This receptor was well-known at the time, and so was aptly suited to adaptation, and allowed for a study of the kinetics as not allowed before.
The expression of light-gated ion channels in a specific cell type through promoter control allows for the regulation of cell potential by either depolarizing the membrane to 0 mV for cation-permeant channelrhodopsin or by holding the voltage at –67 mV for anion-conducting channelrhodopsin. Depolarization can conduct a current in the range of 5 fA per channel and occurs on the timescale of action potentials and neurotransmitter exocytosis. They have an advantage over other types of ion channel regulation in that they provide non-invasive, reversible membrane potential changes with fine temporal and spatial control granted by induction through laser stimuli. They reliably stimulate single action potentials with rapid depolarization and can be utilized in vivo because they do not require high intensity illumination to maintain function, unlike other techniques like light-activated proton pumps and photoactivatable probes.
Examples
Examples of light-gated ion channels occur in both natural and synthetic environments. These include:
Naturally occurring
Channelrhodopsins were the first discovered family of light-gated ion channels.
Channelrhodopsin-1 (from Chlamydomonas reinhardtii and Volvox)
Channelrhodopsin-2
Anion-conducting channelrhodopsin
Synthetically adapted
Nicotinic acetylcholine receptor was the first ion channel to be synthetically adapted with a light-gated mechanism.
Light-activated potassium channels have been engineered from bacterial K+ channels with the goal of inhibiting neuronal activity upon illumination. A second strategy is to combine a cyclic nucleotide gated K+ channel with a photoactivated adenylyl cyclase to inhibit neuronal activity at very low light levels.
Many other fully synthetic, light-gated channels have been produced as well.
References
Ion channels | Light-gated ion channel | Chemistry | 1,190 |
5,112,021 | https://en.wikipedia.org/wiki/2%20Centauri | 2 Centauri is a single star in the southern constellation of Centaurus, located approximately 183 light-years from Earth. It has the Bayer designation g Centauri; 2 Centauri is the Flamsteed designation. This object is visible to the naked eye as faint, red-hued star with an apparent visual magnitude of 4.19. It is moving away from the Earth with a heliocentric radial velocity of +41 km/s. The star is a member of the HR 1614 supercluster.
This is an evolved red giant star with a stellar classification of M5 III. In 1951, Alan William James Cousins announced that the star, then called g Centauri, is a variable star. It was given its variable star designation, V806 Centauri, in 1978. It is classified as a semiregular variable star and its brightness varies from magnitude +4.16 to +4.26 with a period of 12.57 days. The star has around 70 times the Sun's radius and is radiating 72 times the Sun's luminosity from its enlarged photosphere at an effective temperature of .
References
M-type giants
Asymptotic-giant-branch stars
Semiregular variable stars
Centaurus
Centauri, g
Durchmusterung objects
Centauri, 2
120323
067457
5192
Centauri, V806 | 2 Centauri | Astronomy | 294 |
36,541,240 | https://en.wikipedia.org/wiki/Ceramic%20mixing%20technology | Ceramic mixing technology is used to mix and blend ceramics to create end products such as: ceramic powder blends, injection molding feedstock, electronics, decorative finishes, refractory linings, batteries and fuel cells, thermally conductive pastes, investment casting slurries, dental ceramics and advanced composites.
A wide range of equipment is available for these requirements.
External links
Ceramics mixing and blending technical articles
Ceramic engineering | Ceramic mixing technology | Physics,Engineering | 87 |
56,446,915 | https://en.wikipedia.org/wiki/Lamb%20surface | In fluid dynamics, Lamb surfaces are smooth, connected orientable two-dimensional surfaces, which are simultaneously stream-surfaces and vortex surfaces, named after the physicist Horace Lamb. Lamb surfaces are orthogonal to the Lamb vector everywhere, where and are the vorticity and velocity field, respectively. The necessary and sufficient condition are
Flows with Lamb surfaces are neither irrotational nor Beltrami. But the generalized Beltrami flows has Lamb surfaces.
See also
Beltrami flow
References
Fluid dynamics | Lamb surface | Chemistry,Engineering | 100 |
26,979,533 | https://en.wikipedia.org/wiki/Waiter%20Rule | The Waiter Rule refers to a common belief that one's true character can be gleaned from how one treats staff or service workers, such as a "waiter". The rule was one of William H. Swanson's 33 Unwritten Rules of Management, which was copied from Dave Barry's version: "If someone is nice to you but rude to the waiter, they are not a nice person."
References
Interpersonal relationships | Waiter Rule | Biology | 91 |
31,921,181 | https://en.wikipedia.org/wiki/OrientDB | OrientDB is an open source NoSQL database management system written in Java. It is a Multi-model database, supporting graph, document and object models, the relationships are managed as in graph databases with direct connections between records. It supports schema-less, schema-full and schema-mixed modes. It has a strong security profiling system based on users and roles and supports querying with Gremlin along with SQL extended for graph traversal. OrientDB uses several indexing mechanisms based on B-tree and Extendible hashing, the last one is known as "hash index". Each record has Surrogate key which indicates the position of the record on disk. Links between records (edges) are stored either as the record's position stored directly inside of the referrer or as B-tree of record positions (so-called record IDs or RIDs), that serves as a container of RIDs, which allows fast traversal (with O(1) complexity) of one-to-many relationships and fast addition/removal of new links. OrientDB is the 6th most popular graph database according to the DB-Engines graph database ranking, as of January 2024.
The development of OrientDB relies on an open-source community. The project uses GitHub to manage the sources, contributors and versioning.
Engine
OrientDB is built with a multi-model graph/document engine. While OrientDB includes a SQL layer, the support for edges effectively means that these may be used to traverse relationships rather than employing a JOIN statement. OrientDB handles every record / document as an object and the linking between objects / documents is implemented using direct pointers to the record's positions on disk. This leads to quick retrieval of related data as compared to joins in an RDBMS.
Editions & licenses
OrientDB Community Edition is free for any use (Apache 2 license). There is no commercial version of OrientDB.
Applications
Banking
Big Data
Fraud prevention
Loan management software (Floify)
Master data management
Non-coding RNA human interaction database
Recommendation engines
Social networking
Traffic management systems
History
OrientDB was originally authored by Luca Garulli in 2010. Luca wrote it as a Java rewrite of the fast persistent layer of Orient ODBMS database (originally developed by Luca Garulli in 1999 in C++). During 2012–2014 years storage engine was redeveloped by Andrii Lomakin. It has got a new name "plocal" which stands for "paginated local". This name implies that the new storage engine is based on the concept of the splitting of data files by pages and page is treated as a single atomic unit of change. Since 2012, the project is being sponsored by OrientDB LTD (former Orient Technologies LTD), a for-profit company with Luca as its CEO and founder. In 2013 Andrii Lomakin has joined the company as R&D lead engineer and company's co-owner.
The first time the word "multi-model" has been associated to the databases was on May 30, 2012, in Cologne, Germany, during Luca Garulli's keynote "NoSQL Adoption – What’s the Next Step?". Luca Garulli envisioned the evolution of the 1st generation NoSQL products into new products with more features able to be used by multiple use cases. OrientDB was the first product to embrace documents, graphs, key-value, geospatial and reactive models in the same product, at the core level. This means that the multiple models were integrated into the core without using layers. For this reason, OrientDB is a "Native" Multi-model database.
OrientDB has been covered by media outlets and is the winner of the 2015 InfoWorld Bossie award.
On September 15, 2017, OrientDB LTD company has been acquired by CallidusCloud a public company traded on NASDAQ.
On January 30, 2018, it was announced SAP (company) acquired CallidusCloud for $2.4 billion. and therefore OrientDB is now supported by SAP (company).
On September 1, 2021, the original founder Luca Garulli left SAP (company) and created a new database project ArcadeDB with a similar data presentation model after SAP decided to stop providing commercial support for OrientDB.
On December 30, 2024, author of OrientDB storage engine Andrii Lomakin has created his binary compatible fork of OrientDB - YouTrackDB supported by YouTrack team at the moment of writing January 8, 2025.
See also
XML database
References
External links
Free database management systems
Document-oriented databases
Distributed computing architecture
Structured storage
NoSQL
Graph databases | OrientDB | Mathematics | 957 |
64,031,732 | https://en.wikipedia.org/wiki/The%20History%20of%20Mathematical%20Tables | The History of Mathematical Tables: from Sumer to Spreadsheets is an edited volume in the history of mathematics on mathematical tables. It was edited by Martin Campbell-Kelly, Mary Croarken, Raymond Flood, and Eleanor Robson, developed out of the presentations at a conference on the subject organised in 2001 by the British Society for the History of Mathematics, and published in 2003 by the Oxford University Press.
Topics
An introductory chapter classifies tables broadly according to whether they are intended as aids to calculation (based on mathematical formulas) or as analyses and records of data, and further subdivides them according to how they were compiled. Following this, the contributions to the book include articles on the following topics:
Tables of data in Babylonian mathematics, administration, and astronomy, by Eleanor Robson
Early tables of logarithms, by Graham Jagger
Life tables in actuarial science, by Christopher Lewin and Margaret de Valois
The work of Gaspard de Prony constructing mathematical tables in revolutionary France, by Ivor Grattan-Guinness
Difference engines, by Michael Williams
The uses and advantages of machines in table-making, and error correction in mechanical tables, by Doron Swade
Astronomical tables, by Arthur Norberg
The data processing and statistical analyses used to produce tables of census data from punched cards, by Edward Higgs
British table-making committees, and the transition from calculators to computers, by Mary Croarken
The Mathematical Tables Project of the Works Progress Administration, in New York during the Great Depression of the 1930s and early 1940s, by David Alan Grier
The work of the British Nautical Almanac Office, by George A. Wilkins
Spreadsheets, by Martin Campbell-Kelly.
The work is presented on VIII + 361 pages in a unified format with illustrations throughout, and with the historical and biographical context of the material set aside in separate text boxes.
Audience and reception
Reviewer Paul J. Campbell finds it ironic that, unlike the works it discusses, "there are no tables in the back of the book". Reviewer Sandy L. Zabell calls the book "interesting and highly readable".
Both Peggy A. Kidwell and Fernando Q. Gouvêa note several topics that would have been worthwhile to include, including tables in mathematics in medieval Islam or other non-Western cultures, the book printing industry that provided inexpensive books of tables in the 19th century, and the development of mathematical tables in Germany. As Kidwell writes, "like most good books, this one not only tells good stories, but leaves the reader hoping to learn more". Gouvêa evaluates the book as being useful in its coverage of a topic often missed in broader surveys of the history of mathematics, of interest both to historians of mathematics and to a more general audience interested in the development of these topics, and "a must-have for libraries".
References
External links
The History of Mathematical Tables on the Internet Archive
Mathematical tables
Books about the history of mathematics
2003 non-fiction books | The History of Mathematical Tables | Mathematics | 603 |
57,246,115 | https://en.wikipedia.org/wiki/C1orf27 | Uncharacterized protein Chromosome 1 Open Reading Frame 27 is a protein in humans, encoded by the C1orf27 gene. It is accession number NM_017847. This is a membrane protein that is 3926 base pairs long with the most extensive string of amino acids being 454aa long. C1orf27 exhibits cytoplasmic expression in epidermal tissues. Predicted associated biological processes of the gene include cell fate specification and developmental properties.
Gene
Locus
This gene is located on chromosome 1 at 1q31.1. It is encoded on the plus strand of DNA spanning from 186,344,406 to 186,390,514.
mRNA
Alternative splicing
There appear to be four isoforms due to splicing. Two of those are truncated on the 3' end of the protein from 266aa and 396aa. Additional location of alternative splice sites are from 79aa to 102aa and 246aa to 260aa.
Protein
General properties
The primary encoded protein of C1orf27 consists of 454 amino acid residues and is 3926 base pairs long. It consists of 14 total exons. The predicted molecular weight of the primary, unmodified protein is approximately 51.1 kdal.
Aliases
As with many other genes, there are some common aliases found with this gene. Those aliases are Lymphocyte-Activation Gene-1 (LAG1) Interacting Protein, Transparent Testa Glabra 1 (TTG1), and Odorant Response Abnormal 4 (ODR4). The most common alias for C1orf27 is ODR4, and this is what most readily appears when searching the gene.
Composition
Computational analysis revealed the most abundant amino acid to be leucine at 10.1% of the total protein. The second most abundant was serine which contributes to 8.6% of the total protein. Glutamic acid was third most abundant and contributes to 7.7% of the protein. This analysis also revealed that the protein appears to be deficient in tryptophan as it only contributes to 1.1% of the protein. Based on the distribution of other amino acid types, there were five high scoring hydrophobic segments. There were also two transmembrane domains located at 82-98aa and 432-449aa.
Post-translational modifications
C1orf27 is predicted to undergo multiple post translational modifications such as glycosylation, myristoylation, and phosphorylation.
Interactions
There were eight interactions identified by Mentha. The first one was UFSP2 which hydrolyzes the peptide bond at the C-term gly of UFM1, a ubiquitin-like modifier protein bound to a number of target proteins. The second one was HSCB which acts as a co-chaperone in iron-sulfur cluster assembly in mitochondria. The third was GRB2 which is an adapter protein that provides a critical link between cell surface growth factor receptors and the Ras signaling pathway. The fourth was CYLD which is a protease that cleaves Lys-63-linked polyubiquitin chains, controls regulation of cell survival, proliferation, and differentiation, and is required for normal cell cycle progress. The fifth was ATM which activates checkpoint signaling upon double strand breaks, apoptosis, and genotoxic stress. The sixth was FAM177A1, the function of which is unknown. The last two were THID2 and Q81kP6 which are both in bacillus anthracis.
Subcellular localization
The c1orf27 protein is likely cytoplasmic. This was found with 55.5 reliability. The K-NN prediction was k=9/23 and the protein was found to be 55.6% cytoplasmic, 11.1% mitochondrial, 11.1% vacuolar, 11.1% cytoskeletal, and 11.1% golgi.
Structure
Alpha helices predicted in the c1orf27 protein are colored blue in the above picture. Beta sheets are pictured by the red arrows. Random coils are the purple strands between structures.
Expression
Overall, expression of c1orf27 seems to be ubiquitous. Highest expression body sites (>50 TPM) were bladder, bone marrow, kidney, liver, pancreas, parathyroid, and vascular. Highest expression health sites (>50 TPM) were adrenal tumors, cervical tumors, and liver tumors. While both of these observations had relatively high TPM scores, there was still relatively low occurrence. This validates the assumption that expression is ubiquitous. There was moderate expression (>25 TPM) in the human fetus, and expression increased with age. Expression was completely absent in the ears, esophagus, lymph, nerve, salivary glands, thyroid, tonsils, and umbilical cord. There was no expression in bladder carcinoma despite expression being elevated in the bladder itself. There was high expression in endothelial cells and neuronal cells but was undetectable in glial cells and neuropil cells. Expression was also localized to the nucleoplasm and plasma membrane in humans but is localized to the cytosol in mice.
Homology
Paralogs
There were no paralogs of C1orf27 identified in the human genome.
Orthologs
There were orthologs identified in most animals for which there were complete genome data. The most distant, yet still relevant, orthologs identified were invertebrates from phylum Cnidaria.
Molecular Evolution
The m value, or number of corrected amino acid changes per 100 residues, for the C1orf27 gene was graphed against the species divergence in millions of years. When compared to divergence graphs of fibrinogen and cytochrome C, it was determined that this gene closely resembles the evolutionary pattern observed in fibrinogen, suggesting a more rapid rate of evolution. M values for C1orf27 were calculated using the percentage of identity, when compared to humans, observed in the mRNA sequences of the orthologs using the formula derived from the Molecular Clock Hypothesis.
References
Genes on human chromosome 1
Membrane proteins | C1orf27 | Biology | 1,283 |
8,940,073 | https://en.wikipedia.org/wiki/Jetstream%20furnace | Jetstream furnaces (later tempest wood-burning boilers), were an advanced design of wood-fired water heaters conceived by Dr. Richard Hill of the University of Maine in Orono, Maine, USA. The design heated a house to prove the theory, then, with government funding, became a commercial product.
Wood-burning water furnaces, boilers and melters
The furnace used a forced and induced draft fan to draw combustion air and exhaust gases through the combustion chamber at 1/3 of the speed of sound (100 m/s+). The wood was loaded into a vertical tube which passed through the water jacket into a refractory lined combustion chamber. In this chamber the burning took place and was limited to the ends of the logs. The water jacket prevented the upper parts of the logs from burning so they would gravity feed as the log was consumed.
The products of combustion left the chamber and passed through a narrow ceramic neck which reached temperatures of 2000 degrees F where the gases and tars released by the wood completed their burning. The products then passed through a refractory lined ash chamber which slowed the flow and let ash settle out. From here the hot gases travelled up through the boiler tubes which pass through the water jacket. Turbulators in the tubes improve heat transfer to the water jacket.
All this resulted in total efficiencies as high as 85% but more commonly 75-80% and allowed partly dry unsplit wood to be burned just as effectively and cleanly. The particulate production was 100 times less than airtight stoves of the 1970s and 1980s and was less than representative oil fired furnaces. The Jetstream produced approximately 0.1 grams/hours of soot while EPA certified woodstoves produce up to 7.2 grams per hour. The high combustion chamber velocities do result in fine particulate flyash being ejected from the stack.
The other aspect of Dr. Hill's design was the use of water storage. The furnace only operated at one setting, wide-open burn. A full load of hardwood, approximately 40 lbs would be consumed in four hours and the heat released was stored in water tanks for use through the day.
The Hampton Industries model was designed to produce .
A Hampton Jetstream Mk II which was set to be the next model offered by Hampton Industries existed in prototype form. It was an upsized version of the unit offered for sale. The only component changed was the diameter of the burning chamber. This was enlarged within the standard casting. The prototype shares many of the design improvements seen in the Kerr Jetstream.
The Tempest was produced by Dumont Industries of Monmouth, ME, USA and is very similar to the Jetstream.
The patent for this device, termed a WoodFired Quick Recovery Water Heater, number 4583495, issued April 22, 1986, is assigned to the board of trustees of the University of Maine. There is no current production using the design of this patent. (January, 2008)
Production history
Hampton Industries of Hampton, PEI, Canada, pursued the design to fit into houses more easily.
Hampton Industries produced the Jetstream from January 1980 to June 1981 producing 500 units. At this point the company ceased operations with unfilled orders for hundreds more stoves and sales approximately 25% higher than projected. It was stated the advertising costs incurred before production depleted the principals in the business and a deal with a venture capitalist fell through at the last minute.
Within 4 weeks of entering receivership, Kerr Controls Ltd of Truro, Nova Scotia had purchased the manufacturing rights and resumed production of the slightly redesigned Jetstream in mid-September 1981 and produced 150 units just in the last quarter of 1981.
The Kerr Jetstream incorporated several updates including the available belt-driven fan replacing the Electrolux vacuum cleaner motor originally used. A removable refractory plug allowing access to the tunnel was added in the back of the unit. An updated control panel was adopted and the option of an electronic panel was added.
The design of the Hampton Industries furnaces and spare parts belong to Kerr Heating Products of Parrsboro, Nova Scotia. Some molds to replace parts still exist and are available through Kerr Controls or Kerr Heating.
Alternate designs
Current (2007) furnaces with similar designs:
Solo Series Wood Gasification Boilers by HS -Tarm
Alternate Heating Systems (AHS)
The Greenwood Hydronic Wood Furnace
Garn WHS
Kunzel Wood Gasification Boilers
Alternative Fuel Gasification
The EKO-LINE and KP-PYRO Boilers and Goliath Commercial Boiler from New Horizon Corporation Inc.
These companies use a process called gasification but the basics of forced draft, twin refractory lined combustion and ash chambers linked by a ceramic or refractory burner nozzle or tube and shell and tube heat exchanger remain common.
External links
(Hill's 1979 DOE Grant Report)
See also
Furnace
Hydronics
Gasification
Wood gas
Wood gas generator
References
Boilers
Plumbing
Heating, ventilation, and air conditioning | Jetstream furnace | Chemistry,Engineering | 1,008 |
3,569,469 | https://en.wikipedia.org/wiki/SOS%20%28paper-and-pencil%20game%29 | SOS is paper and pencil game for two or more players. It is similar to tic-tac-toe and dots and boxes, but has much greater complexity.
SOS is a combinatorial game when played with two players. In terms of game theory, it is a zero-sum, sequential game with perfect information.
Gameplay
Before play begins, a square grid of at least 3×3 squares in size is drawn. Players take turns to add either an "S" or an "O" to any square, with no requirement to use the same letter each turn. The object of the game is for each player to attempt to create the straight sequence S-O-S among connected squares (either diagonally, horizontally, or vertically), and to create as many such sequences as they can. If a player succeeds in creating an SOS, that player immediately takes another turn, and continues to do so until no SOS can be created on their turn. Otherwise turns alternate between players after each move.
Keeping track of who made which SOSs can be done by, e.g., one player circling their SOSs and the other player drawing a line through theirs. Once the grid has been filled up, the winner is the player who made the most SOSs. If the grid is filled up and the number of SOSs for each player is the same, then the game is a draw.
The game can also be played where the player who creates an SOS is the winner and if no SOSs are created the game is a draw.
References
External links
"An Assortment of Combinatorial Games," pg. 8, at Prof. Hugh L. Montgomery's University of Michigan website. Also available in PostScript format.
Abstract strategy games
Mathematical games
Paper-and-pencil games
Tic-tac-toe variants | SOS (paper-and-pencil game) | Mathematics | 375 |
43,364,288 | https://en.wikipedia.org/wiki/Xiaomi%20Mi%204 | The Xiaomi Mi 4 () is a smartphone developed by the Chinese electronics manufacturer Xiaomi for its high-end smartphone line, and was released in August 2014. Xiaomi held an event to formally introduce the high-end phone, and its complementary smart-accessory, the Xiaomi MiBand, during the Xiaomi New Product Launch Event 2014 on 22 July 2014.
Similar to the principle of the Xiaomi Mi2, the Mi 4 is a highly revamped version of its predecessor, the Xiaomi Mi3. The phone is of a different design to its predecessor. It was also released slightly before the new MIUI 6, which was introduced in August 2014.
Reception towards the device was generally positive, though there were still a high amount of negative feedback from users of Apple's iPhone due to its similar design and quality. Some media companies hailed it to be one of the best smartphones available in the market due to its high-end hardware which is sold at a lower price compared to competitor smartphones. However, others criticized it for being too similar to Apple's iPhone 5S.
History
Before its official unveiling, media speculation primarily focused on leaks; including photos of the early prototypes of the device and screenshots of MIUI 6, these leaks were later proven to be fake.
Xiaomi announced the Mi 4 and MiBand during a media event at the CNCC on 22 July 2014. While the device was announced in July 2014, it didn't become available until August 2014, shortly before unveiling MIUI 6.
In August 2014, the Mi 4 was released in China and then to other countries. Xiaomi operated in a limited, however expanding, list of countries and consumers outside of the countries it operates in have to buy it online.
Features
Operating system and software
The Xiaomi Mi 4 ships with MIUI V5 (upgradable to MIUI V10), Xiaomi's variant of the Android operating system. The user interface of MIUI is based on the concept of direct manipulation, using multi-touch gestures. Interface control elements consist of sliders, switches, and buttons. Interaction with the OS includes gestures such as swipe, tap, pinch and reverse pinch, all of which have specific definitions within the context of the Android operating system and its multi-touch interface. Internal accelerometers are used by some applications to respond to the movement of the device such as rotating it vertically (one common result is switching from portrait to landscape mode). The device includes an updater application that allows it to update its OS to the latest version of MIUI available to it.
Windows 10 Mobile ROM Port
In March 2015, it was announced that selected registered users of Mi 4 devices in China would receive a ROM port of the Windows 10 Mobile operating system as a trial partnership between Xiaomi and Microsoft. The ROM flash download was released for these users in June 2015, who could then test the software on their devices and provide feedback to both Microsoft and Xiaomi.
Design
The device has a 5-inch (12.7 cm) Sharp/JDI OGS fully laminated touchscreen, with a screen resolution of 1080x1920 at a pixel density of 441 ppi. Its home button is similar to its predecessor and is mainly touch-based with adjustable haptic feedback. The phone itself weighs 149 grams (5.26 oz) and uses a stainless steel frame. The device is currently available in three color finishes, black, white and rose gold.
Hardware
The Xiaomi Mi 4 is powered by a Qualcomm Snapdragon 801 (MSM8974-AC) chipset, which, at one point made it the fastest Android smartphone to date according to the AnTuTu benchmark application. Its processor is a quad-core 2.5 GHz Krait 400 and its graphics card is an Adreno 330. The phone includes a 3080 mAh battery, which provides 280 hours of standby time. It comes with a 13 megapixel primary camera and an 8 megapixel secondary camera. Xiaomi also released another model of Mi 4 with 64 GB of internal memory.
Accessories
The Xiaomi Mi 4 was announced with a complementary US$12 smart accessory known as the Xiaomi Mi Band which is a waterproof sleep-cycle smart alarm, fitness monitor, sleep tracker and remote smartphone unlocker. It comes in various exchangeable bands and has a 30-day battery capacity.
Compatibility with CyanogenMod and dual-boot
The phone is compatible with CM13, CM14.1 and supports true dual-boot.
See also
Comparison of smartphones
References
Android (operating system) devices
Mobile phones introduced in 2014
Discontinued flagship smartphones
Mi 4
Mobile phones with 4K video recording
Mobile phones with infrared transmitter
Windows 10 Mobile devices | Xiaomi Mi 4 | Technology | 979 |
244,305 | https://en.wikipedia.org/wiki/Contention%20free%20pollable | Contention-free pollable (CF-Pollable) is a state of operation for wireless networking nodes. The condition is saying that the node is able to use the Point Coordination Function, as opposed to the Distributed Coordination Function, within a wireless LAN.
A device that is able to use point coordination function is one that is able to participate in a method to provide limited Quality of service (for time sensitive data) within the network.
See also
Contention (telecommunications)
References
Wireless networking | Contention free pollable | Technology,Engineering | 97 |
42,053,050 | https://en.wikipedia.org/wiki/Tetraanthraporphyrin | Tetraanthraporphyrin, or tetraanthra[2,3]porphyrin (TAP), is a representative of extended porphyrins.
Despite promising properties, tetraanthraporphyrins have until recently been little studied. As was theoretically predicted,
extension of pi-electronic system results in the case of TAPs in the destabilization of the third LUMOs and the first HOMOs that makes it unstable against oxidation and reduction.
Synthesis
The first representative of the TAP family was prepared by Kobayashi and co-workers, using high-temperature template condensation method, which resembles the classical procedures of phthalocyanine synthesis. Melting of anthracene-2,3-
dicarboxyimide with sodium biphenylacetate in the presence of zinc acetate resulted in the formation of zinc complex of triarylsubstituted TAP. The synthesis of both meso-unsubstituted and meso-arylsubstituted TAPs was reported by Ono and coworkers using a common approach to extended porphyrins relying on thermal retro-Diels−Alder extrusion of ethylene
from bicyclo[2.2.2]octadiene-annelated porphyrins. Thus obtained materials were reported to be poorly soluble and unstable toward photooxidation.
An obvious drawback of reported syntheses of TAPs is a need for harsh conditions of condensation or aromatization steps, which are poorly compatible with the emerging huge and fragile TAP system. This results in low yields and poor quality of the obtained materials and limits opportunities of introducing functionality to improve solubility and stability or to modulate optical properties.
As an advanced method delivering tetraanthraporphyrins, the dihydroisoindole method based on an oxidative aromatization of the closest partially hydrogenated porphyrin precursor was applied. It warrants that the conditions of aromatization of
the annelated system are as soft as possible and occur spontaneously along with the aromatization of the porphyrinogen
intermediates
Structure
The geometry of TAP like all known geometries of tetraarylporphyrins is distorted to take a very characteristic “saddle” shape.
Optical properties
Tetraanthraporphyrin exhibit strongly red-shifted and hyperchromic absorption bands. The maximum of absorption is about 830 nm. The molar extinction coefficients reach 10−5 scale. Very strong red-shift of absorption by about 90 nm upon protonation of nitrogen atoms and blue-shift by 20−40 nm upon metal insertion are observed.
References
External links
Society of Porphyrins and Phthalocyanines
Journal of Porphyrins and Phthalocyanines
Cambridge Crystallographic Data Centre (CCDC # 900743)
Macrocycles
Tetrapyrroles | Tetraanthraporphyrin | Chemistry | 589 |
53,011,652 | https://en.wikipedia.org/wiki/Half%20a%20Moon%20and%20One%20Whole%20Star | Half a Moon and One Whole Star is a 1986 book by Crescent Dragonwagon and illustrator Jerry Pinkney about a girl, Susan, who falls asleep in her bed, while the world continues outside.
Reception
Publishers Weekly in a review of Half a Moon and One Whole Star, wrote " Half A Moon and One Whole Star is an exceptional children's book: a work of art, both literary and visual." and School Library Journal called it "a soft symphony of sleep in which participants are both real and imagined."
Kirkus Reviews wrote "The cadence and the sensual images of the text, coupled with the artist's direct, yet subtly disjointed pictures in vivid watery colors, combine for a harmonious nighttime symphony of sound and color."
Half a Moon received the 1987 Coretta Scott King Illustrator Award.
References
1986 children's books
1986 poetry books
American picture books
American poetry collections
Children's poetry books
Picture books by Jerry Pinkney
Coretta Scott King Award–winning works
Sleep in fiction | Half a Moon and One Whole Star | Biology | 206 |
59,041,446 | https://en.wikipedia.org/wiki/Telmatocola | Telmatocola is a genus of bacteria from the family of Planctomycetaceae with one known species (Telmatocola sphagniphila).
Telmatocola sphagniphila has been isolate from Sphagnum peat from Staroselsky moss from the Tver Region.
See also
List of bacterial orders
List of bacteria genera
References
Bacteria genera
Monotypic bacteria genera
Planctomycetota | Telmatocola | Biology | 88 |
160,220 | https://en.wikipedia.org/wiki/Ratite | Ratites () are a polyphyletic group consisting of all birds within the infraclass Palaeognathae that lack keels and cannot fly. They are mostly large, long-necked, and long-legged, the exception being the kiwi, which is also the only nocturnal extant ratite.
The understanding of relationships within the paleognath clade has been in flux. Previously, all the flightless members had been assigned to the order Struthioniformes, which is more recently regarded as containing only the ostrich. The modern bird superorder Palaeognathae consists of ratites and the flighted Neotropic tinamous (compare to Neognathae). Unlike other flightless birds, the ratites have no keel on their sternum—hence the name, from the Latin ('raft', a vessel which has no keel—in contradistinction to extant flighted birds with a keel). Without this to anchor their wing muscles, they could not have flown even if they had developed suitable wings. Ratites are a polyphyletic group; tinamous fall within them, and are the sister group of the extinct moa. This implies that flightlessness is a trait that evolved independently multiple times in different ratite lineages.
Most parts of the former supercontinent Gondwana have ratites, or did have until the fairly recent past. So did Europe in the Paleocene and Eocene, from where the first flightless paleognaths are known. Ostriches were present in Asia as recently as the Holocene, although the genus is thought to have originated in Africa. However, the ostrich order may have evolved in Eurasia. A recent study posits a Laurasian origin for the clade. Geranoidids, which may have been ratites, existed in North America.
Species
Living forms
The African ostrich is the largest living ratite. A large member of this species can be nearly tall, weigh as much as , and can outrun a horse.
Of the living species, the Australian emu is next in height, reaching up to tall and about . Like the ostrich, it is a fast-running, powerful bird of the open plains and woodlands.
Also native to Australia and the islands to the north are the three species of cassowary. Shorter than an emu, but heavier and solidly built, cassowaries prefer thickly vegetated tropical forest. They can be dangerous when surprised or cornered because of their razor-sharp talons. In New Guinea, cassowary eggs are brought back to villages and the chicks raised for eating as a much-prized delicacy, despite (or perhaps because of) the risk they pose to life and limb. They reach up to tall and weigh as much as
South America has two species of rhea, large fast-running birds of the Pampas. The larger American rhea grows to about tall and usually weighs .
The smallest ratites are the five species of kiwi from New Zealand. Kiwi are chicken-sized, shy, and nocturnal. They nest in deep burrows and use a highly developed sense of smell to find small insects and grubs in the soil. Kiwi are notable for laying eggs that are very large in relation to their body size. A kiwi egg may equal 15 to 20 percent of the body mass of a female kiwi. The smallest species of kiwi is the little spotted kiwi, at and .
Holocene extinct forms
At least nine species of moa lived in New Zealand before the arrival of humans, ranging from turkey-sized to the giant moa Dinornis robustus with a height of and weighing about . They became extinct by A.D. 1400 due to hunting by Māori settlers, who arrived around A.D. 1280.
Aepyornis maximus, the "elephant bird" of Madagascar, was the heaviest bird ever known. Although shorter than the tallest moa, a large A. maximus could weigh over and stand up to tall. Accompanying it were three other species of Aepyornis as well as three species of the smaller genus Mullerornis. All these species went into decline following the arrival of humans on Madagascar around 2,000 years ago, and were gone by the 17th or 18th century if not earlier.
Classification
There are two taxonomic approaches to ratite classification: one combines the groups as families in the order Struthioniformes, while the other supposes that the lineages evolved mostly independently and thus elevates the families to order rank (Rheiformes, Casuariformes etc.).
Evolution
The longstanding story of ratite evolution was that they share a common flightless ancestor that lived in Gondwana, whose descendants were isolated from each other by continental drift, which carried them to their present locations. Supporting this idea, some studies based on morphology, immunology and DNA sequencing reported that ratites are monophyletic. Cracraft's 1974 biogeographic vicariance hypothesis suggested that ancestral flightless paleognaths, the ancestors of ratites, were present and widespread in Gondwana during the Late Cretaceous. As the supercontinent fragmented due to plate tectonics, they were carried by plate movements to their current positions and evolved into the species present today. The earliest known ratite fossils date to the Paleocene epoch about 56 million years ago (e.g., Diogenornis, a possible early relative of the rhea). However, more primitive paleognaths are known from several million years earlier, and the classification and membership of the Ratitae itself is uncertain. Some of the earliest ratites occur in Europe.
Recent analyses of genetic variation between the ratites do not support this simple picture. The ratites may have diverged from one another too recently to share a common Gondwanan ancestor. Also, the Middle Eocene ratites such as Palaeotis and Remiornis from Central Europe may imply that the "out-of-Gondwana" hypothesis is oversimplified.
Molecular phylogenies of the ratites have generally placed ostriches in the basal position and among extant ratites, placed rheas in the second most basal position, with Australo-Pacific ratites splitting up last; they have also shown that both the latter groups are monophyletic. Early mitochondrial genetic studies that failed to make ostriches basal were apparently compromised by the combination of rapid early radiation of the group and long terminal branches. A morphological analysis that created a basal New Zealand clade has not been corroborated by molecular studies. A 2008 study of nuclear genes shows ostriches branching first, followed by rheas and tinamous, then kiwi splitting from emus and cassowaries. In more recent studies, moas and tinamous were shown to be sister groups, and elephant birds were shown to be most closely related to the New Zealand kiwi. Additional support for the latter relationship was obtained from morphological analysis.
The finding that tinamous nest within this group, originally based on twenty nuclear genes and corroborated by a study using forty novel nuclear loci makes 'ratites' polyphyletic rather than monophyletic, if we exclude the tinamous. Since tinamous are weak fliers, this raises interesting questions about the evolution of flightlessness in this group. The branching of the tinamous within the ratite radiation suggests flightlessness evolved independently among ratites at least three times. More recent evidence suggests this happened at least six times, or once in each major ratite lineage. Re-evolution of flight in the tinamous would be an alternative explanation, but such a development is without precedent in avian history, while loss of flight is commonplace.
By 2014, a mitochondrial DNA phylogeny including fossil members placed ostriches on the basal branch, followed by rheas, then a clade consisting of moas and tinamous, followed by the final two branches: a clade of emus plus cassowaries and one of elephant birds plus kiwis.
Vicariant speciation based on the plate tectonic split-up of Gondwana followed by continental drift would predict that the deepest phylogenetic split would be between African and all other ratites, followed by a split between South American and Australo-Pacific ratites, roughly as observed. However, the elephant bird–kiwi relation appears to require dispersal across oceans by flight, as apparently does the colonization of New Zealand by the moa and possibly the back-dispersal of tinamous to South America, if the latter occurred. The phylogeny as a whole suggests not only multiple independent origins of flightlessness, but also of gigantism (at least five times). Gigantism in birds tends to be insular; however, a ten-million-year-long window of opportunity for evolution of avian gigantism on continents may have existed following the extinction of the non-avian dinosaurs, in which ratites were able to fill vacant herbivorous niches before mammals attained large size. Some authorities, though, have been skeptical of the new findings and conclusions.
Kiwi and tinamous are the only palaeognath lineages not to evolve gigantism, perhaps because of competitive exclusion by giant ratites already present on New Zealand and South America when they arrived or arose. The fact that New Zealand has been the only land mass to recently support two major lineages of flightless ratites may reflect the near total absence of native mammals, which allowed kiwi to occupy a mammal-like nocturnal niche. However, various other landmasses such as South America and Europe have supported multiple lineages of flightless ratites that evolved independently, undermining this competitive exclusion hypothesis.
Most recently, studies on genetic and morphological divergence and fossil distribution show that paleognaths as a whole probably had an origin in the northern hemisphere. Early Cenozoic northern hemisphere paleognaths such as Lithornis, Pseudocrypturus, Paracathartes and Palaeotis appear to be the most basal members of the clade. The various ratite lineages were probably descended from flying ancestors that independently colonised South America and Africa from the north, probably initially in South America. From South America, they could have traveled overland to Australia via Antarctica, (by the same route marsupials are thought to have used to reach Australia) and then reached New Zealand and Madagascar via "sweepstakes" dispersals (rare low probability dispersal methods, such as long distance rafting) across the oceans. Gigantism would have evolved subsequent to trans-oceanic dispersals.
Loss of flight
Loss of flight allows birds to eliminate the costs of maintaining various flight-enabling adaptations like high pectoral muscle mass, hollow bones and a light build, et cetera. The basal metabolic rate of flighted species is much higher than that of flightless terrestrial birds. But energetic efficiency can only help explain the loss of flight when the benefits of flying are not critical to survival.
Research on flightless rails indicates the flightless condition evolved in the absence of predators. This shows flight to be generally necessary for survival and dispersal in birds. In apparent contradiction to this, many landmasses occupied by ratites are also inhabited by predatory mammals. However, the K–Pg extinction event created a window of time with large predators absent that may have allowed the ancestors of extant flightless ratites to evolve flightlessness. They subsequently underwent selection for large size. One hypothesis suggests that as predation pressure decreases on islands with low raptor species richness and no mammalian predators, the need for large, powerful flight muscles that make for a quick escape decreases. Moreover, raptor species tend to become generalist predators on islands with low species richness, as opposed to specializing in the predation of birds. An increase in leg size compensates for a reduction in wing length in insular birds that have not lost flight by providing a longer lever to increase force generated during the thrust that initiates takeoff.
Description
Ratites in general have many physical characteristics in common, although many are not shared by the family Tinamidae, or tinamous. First, the breast muscles are underdeveloped. They do not have keeled sterna. Their wishbones (furculae) are almost absent. They have simplified wing skeletons and musculature. Their legs are stronger and do not have air chambers, except the femurs. Their tail and flight feathers have retrogressed or have become decorative plumes. They have no feather vanes, which means they do not need to oil their feathers, hence they have no preen glands. They have no separation of pterylae (feathered areas) and apteria (non-feathered areas), and finally, they have palaeognathous palates.
Ostriches have the greatest dimorphism, rheas show some dichromatism during the breeding season. Emus, cassowaries, and kiwis show some dimorphism, predominantly in size.
While the ratites share a lot of similarities, they also have major differences. Ostriches have only two toes, with one being much larger than the other. Cassowaries have developed long inner toenails, used defensively. Ostriches and rheas have prominent wings; although they do not use them to fly, they do use them in courtship and predator distraction.
Without exception, ratite chicks are capable of swimming and even diving.
On an allometric basis, paleognaths have generally smaller brains than neognaths. Kiwis are exceptions to this trend, and possess proportionally larger brains comparable to those of parrots and songbirds, though evidence for similar advanced cognitive skills is currently lacking.
Gallery of living species
Behavior and ecology
Feeding and diet
Ratite chicks tend to be more omnivorous or insectivorous; similarities in adults end with feeding, as they all vary in diet and length of digestive tract, which is indicative of diet. Ostriches, with the longest tracts at , are primarily herbivorous. Rheas' tracts are next longest at , and they also have caeca. They are also mainly herbivores, concentrating on broad-leafed plants. However, they will eat insects if the opportunity arises. Emus have tracts of length, and have a more omnivorous diet, including insects and other small animals. Cassowaries have next to the shortest tracts at . Finally, kiwi have the shortest tracts and eat earthworms, insects, and other similar creatures. Moas and elephant birds were the largest native herbivores in their faunas, far larger than contemporary herbivorous mammals in the latter's case.
Some extinct ratites might have had odder lifestyles, such as the narrow-billed Diogenornis and Palaeotis, compared to the shorebird-like lithornithids, and could imply similar animalivorous diets.
Reproduction
Ratites are different from the flying birds in that they needed to adapt or evolve certain features to protect their young. First and foremost is the thickness of the shells of their eggs. Their young are hatched more developed than most and they can run or walk soon thereafter. Also, most ratites have communal nests, where they share the incubating duties with others. Ostriches, and great spotted kiwis, are the only ratites where the female incubates; they share the duties, with the males incubating at night. Cassowaries and emu are polyandrous, with males incubating eggs and rearing chicks with no obvious contribution from females. Ostriches and rheas are polygynous with each male courting several females. Male rheas are responsible for building nests and incubating while ostrich males incubate only at night. Kiwis stand out as the exception with extended monogamous reproductive strategies where either the male alone or both sexes incubate a single egg. Unlike most birds, male ratites have a phallus that is inserted into the female's cloaca during copulation.
Ratites and humans
Ratites and humans have had a long relationship starting with the use of the egg for water containers, jewelry, or other art medium. Male ostrich feathers were popular for hats during the 18th century, which led to hunting and sharp declines in populations. Ostrich farming grew out of this need, and humans harvested feathers, hides, eggs, and meat from the ostrich. Emu farming also became popular for similar reasons and for their emu oil. Rhea feathers are popular for dusters, and eggs and meat are used for chicken and pet feed in South America. Ratite hides are popular for leather products like shoes.
United States regulation
The USDA's Food Safety and Inspection Service (FSIS) began a voluntary, fee-for-service ratite inspection program in 1995 to help the fledgling industry improve the marketability of the meat. A provision in the FY2001 USDA appropriations act (P.L. 106–387) amended the Poultry Products Inspection Act to make federal inspection of ratite meat mandatory as of April 2001 (21 U.S.C. 451 et seq.).
See also
List of Struthioniformes by population
References
External links
Websites With Information On Ratites
Flightless birds
Extant Thanetian first appearances
Taxa named by William Plane Pycraft
Polyphyletic groups | Ratite | Biology | 3,596 |
24,167,903 | https://en.wikipedia.org/wiki/C18H21NO4 | The molecular formula C18H21NO4 (molar mass: 315.36 g/mol) may refer to:
Codeine-N-oxide
Homolycorine
14-Methoxydihydromorphinone
Oxycodone
2C2-NBOMe
Molecular formulas | C18H21NO4 | Physics,Chemistry | 64 |
11,547,963 | https://en.wikipedia.org/wiki/Cryptosporium%20minimum | Cryptosporium minimum is an ascomycete fungus that is a plant pathogen.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungal plant pathogens and diseases
Enigmatic Ascomycota taxa
Fungi described in 1907
Fungus species | Cryptosporium minimum | Biology | 52 |
10,320,021 | https://en.wikipedia.org/wiki/Triethylaluminium | Triethylaluminium is one of the simplest examples of an organoaluminium compound. Despite its name the compound has the formula Al2(C2H5)6 (abbreviated as Al2Et6 or TEA). This colorless liquid is pyrophoric. It is an industrially important compound, closely related to trimethylaluminium.
Structure and bonding
The structure and bonding in Al2R6 and diborane are analogous (R = alkyl). Referring to Al2Me6, the Al-C(terminal) and Al-C(bridging) distances are 1.97 and 2.14 Å, respectively. The Al center is tetrahedral. The carbon atoms of the bridging ethyl groups are each surrounded by five neighbors: carbon, two hydrogen atoms and two aluminium atoms. The ethyl groups interchange readily intramolecularly. At higher temperatures, the dimer cracks into monomeric AlEt3.
Synthesis and reactions
Triethylaluminium can be formed via several routes. The discovery of an efficient route was a significant technological achievement. The multistep process uses aluminium, hydrogen gas, and ethylene, summarized as follows:
2 Al + 3 H2 + 6 C2H4 → Al2Et6
Because of this efficient synthesis, triethylaluminium is one of the most available organoaluminium compounds.
Triethylaluminium can also be generated from ethylaluminium sesquichloride (Al2Cl3Et3), which arises by treating aluminium powder with chloroethane. Reduction of ethylaluminium sesquichloride with an alkali metal such as sodium gives triethylaluminium:
6 Al2Cl3Et3 + 18 Na → 3 Al2Et6 + 6 Al + 18 NaCl
Reactivity
The Al–C bonds of triethylaluminium are polarized to such an extent that the carbon is easily protonated, releasing ethane:
Al2Et6 + 6 HX → 2 AlX3 + 6 EtH
For this reaction, even weak acids can be employed such as terminal acetylenes and alcohols.
The linkage between the pair of aluminium centres is relatively weak and can be cleaved by Lewis bases (L) to give adducts with the formula AlEt3L:
Al2Et6 + 2 L → 2 LAlEt3
Applications
Precursors to fatty alcohols
Triethylaluminium is used industrially as an intermediate in the production of fatty alcohols, which are converted to detergents. The first step involves the oligomerization of ethylene by the Aufbau reaction, which gives a mixture of trialkylaluminium compounds (simplified here as octyl groups):
Al2(C2H5)6 + 18 C2H4 → Al2(C8H17)6
Subsequently, these trialkyl compounds are oxidized to aluminium alkoxides, which are then hydrolysed:
Al2(C8H17)6 + 3 O2 → Al2(OC8H17)6
Al2(OC8H17)6 + 6 H2O → 6 C8H17OH + 2 Al(OH)3
Co-catalysts in olefin polymerization
A large amount of TEAL and related aluminium alkyls are used in Ziegler-Natta catalysis. They serve to activate the transition metal catalyst both as a reducing agent and an alkylating agent. TEAL also functions to scavenge water and oxygen.
Reagent in organic and organometallic chemistry
Triethylaluminium has niche uses as a precursor to other organoaluminium compounds, such as diethylaluminium cyanide:
Pyrophoric agent
Triethylaluminium ignites on contact with air and will ignite and/or decompose on contact with water, and with any other oxidizer—it is one of the few substances sufficiently pyrophoric to ignite on contact with cryogenic liquid oxygen. The enthalpy of combustion, ΔcH°, is (–22.36 kJ/g). Its easy ignition makes it particularly desirable as a rocket engine ignitor. The SpaceX Falcon 9 rocket uses a triethylaluminium-triethylborane mixture as a first-stage ignitor.
Triethylaluminium thickened with polyisobutylene is used as an incendiary weapon, as a pyrophoric alternative to napalm; e.g., in the M74 clip holding four rockets for the M202A1 launchers. In this application it is known as TPA, for thickened pyrotechnic agent or thickened pyrophoric agent. The usual amount of the thickener is 6%. The amount of thickener can be decreased to 1% if other diluents are added. For example, n-hexane, can be used with increased safety by rendering the compound non-pyrophoric until the diluent evaporates, at which point a combined fireball results from both the triethylaluminium and the hexane vapors. The M202 was withdrawn from service in the mid-1980s owing to safety, transport, and storage issues. Some saw limited use in the Afghanistan War against caves and fortified compounds.
See also
Triethylborane, used as an ignitor in the Pratt & Whitney J58 turbojet/ramjet engines.
Trimethylaluminium
References
Organoaluminium compounds
Rocket propellants
Rocket fuels
Incendiary weapons
Pyrophoric materials
Ethyl compounds | Triethylaluminium | Chemistry,Technology | 1,180 |
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