id int64 39 79M | url stringlengths 31 227 | text stringlengths 6 334k | source stringlengths 1 150 ⌀ | categories listlengths 1 6 | token_count int64 3 71.8k | subcategories listlengths 0 30 |
|---|---|---|---|---|---|---|
1,627,862 | https://en.wikipedia.org/wiki/Eclipsed%20conformation | In chemistry an eclipsed conformation is a conformation in which two substituents X and Y on adjacent atoms A, B are in closest proximity, implying that the torsion angle X–A–B–Y is 0°. Such a conformation can exist in any open chain, single chemical bond connecting two sp3-hybridised atoms, and it is normally a conformational energy maximum. This maximum is often explained by steric hindrance, but its origins sometimes actually lie in hyperconjugation (as when the eclipsing interaction is of two hydrogen atoms).
In the example of ethane, two methyl groups are connected with a carbon-carbon sigma bond, just as one might connect two Lego pieces through a single "stud" and "tube". With this image in mind, if the methyl groups are rotated around the bond, they will remain connected; however, the shape will change. This leads to multiple possible three-dimensional arrangements, known as conformations, conformational isomers (conformers), or sometimes rotational isomers (rotamers).
Organic chemistry
Conformations can be described by dihedral angles, which are used to determine the placements of atoms and their distance from one another and can be visualized by Newman projections. A dihedral angle can indicate staggered and eclipsed orientation, but is specifically used to determine the angle between two specific atoms on opposing carbons. Different conformations have unequal energies, creating an energy barrier to bond rotation which is known as torsional strain. In particular, eclipsed conformations tend to have raised energies due to the repulsion of the electron clouds of the eclipsed substituents. The relative energies of different conformations can be visualized using graphs. In the example of ethane, such a graph shows that rotation around the carbon-carbon bond is not entirely free but that an energy barrier exists. The ethane molecule in the eclipsed conformation is said to suffer from torsional strain, and by a rotation around the carbon carbon bond to the staggered conformation around 12.5 kJ/mol of torsional energy is released. In the case of butane and its four-carbon chain, three carbon-carbon bonds are available to rotate. The example below is looking down the C2 and C3 bond. Below is the sawhorse and Newman representation of butane in an eclipsed conformation with the two CH3 groups (C1 and C4) at a 0-degree angle from one another (left).
If the front is rotated 60° clockwise, the butane molecule is now in a staggered conformation (right). This conformation is more specifically referred to as the gauche conformation of butane. This is due to the fact that the methyl groups are staggered, but only 60° from one another. This conformation is more energetically favored than the eclipsed conformation, but it is not the most energetically favorable conformation. Another 60° rotation gives us a second eclipsed conformation where both methyl groups are aligned with hydrogen atoms. One more 60 rotation produces another staggered conformation referred to as the anti conformation. This occurs when the methyl groups are positioned opposite (180°) of one another. This is the most energetically favorable conformation.
The minima can be seen on the graph at 60, 180 and 300 degrees while the maxima can bee see at 0, 120, 240, and 360 degrees. The maxima represent the eclipsed conformations due to the dihedral angle of zero degrees.
Structural applications
As established by X-ray crystallography, octachlorodimolybdate(II) anion ([Mo2Cl8]4-) has an eclipsed conformation. This sterically unfavorable geometry is given as evidence for a quadruple bond between the Mo centers.
Experiments such as X-ray and electron diffraction analyses, nuclear magnetic resonance, microwave spectroscopies, and more have allowed researchers to determine which cycloalkane structures are the most stable based on the different possible conformations. Another method that was shown successful is molecular mechanics, a computational method that allows the total strain energies of different conformations to be found and analyzed. It was found that the most stable conformations had lower energies based on values of energy due to bond distances and bond angles.
In many cases, isomers of alkanes with branched chains have lower boiling points than those that are unbranched, which has been shown through experimentation with isomers of C8H18. This is because of a combination of intermolecular forces and size that results from the branched chains. The more branches that an alkane has, the more extended its shape is; meanwhile, if it is less branched then it will have more intermolecular attractive forces that will need to be broken which is the cause of the increased boiling point for unbranched alkanes. In another case, 2,2,3,3-tetramethylbutane is shaped more like an ellipsoid causing it to be able to form a crystal lattice which raises the melting point of the molecule because it will take more energy to transition from a solid to a liquid state.
See also
Gauche effect
References
Stereochemistry | Eclipsed conformation | [
"Physics",
"Chemistry"
] | 1,086 | [
"Spacetime",
"Stereochemistry",
"Space",
"nan"
] |
1,628,043 | https://en.wikipedia.org/wiki/Adaptationism | Adaptationism is a scientific perspective on evolution that focuses on accounting for the products of evolution as collections of adaptive traits, each a product of natural selection with some adaptive rationale or raison d'etre.
A formal alternative would be to look at the products of evolution as the result of neutral evolution, in terms of structural constraints, or in terms of a mixture of factors including (but not limited to) natural selection.
The most obvious justification for an adaptationist perspective is the belief that traits are, in fact, always adaptations built by natural selection for their functional role. This position is called "empirical adaptationism" by Godfrey-Smith. However, Godfrey-Smith also identifies "methodological" and "explanatory" flavors of adaptationism, and argues that all three are found in the evolutionary literature (see for explanation).
Although adaptationism has always existed— the view that the features of organisms are wonderfully adapted predates evolutionary thinking— and was sometimes criticized for its "Panglossian" excesses (e.g., by Bateson or Haldane), concerns about the role of adaptationism in scientific research did not become a major issue of debate until evolutionary biologists Stephen Jay Gould and Richard Lewontin penned a famous critique, "The Spandrels of San Marco and the Panglossian Paradigm".
According to Gould and Lewontin, evolutionary biologists had a habit of proposing adaptive explanations for any trait by default without considering non-adaptive alternatives, and often by conflating products of adaptation with the process of natural selection. They identified neutral evolution and developmental constraints as potentially important non-adaptive factors and called for alternative research agendas.
This critique provoked defenses by Mayr, Reeve and Sherman and others, who argued that the adaptationist research program was unquestionably highly successful, and that the causal and methodological basis for considering alternatives was weak. The "Spandrels paper" (as it came to be known) also added fuel to the emergence of an alternative "evo-devo" agenda focused on developmental "constraints"
Today, molecular evolutionists often cite neutral evolution as the null hypothesis in evolutionary studies, i.e., offering a direct contrast to the adaptationist approach. Constructive neutral evolution has been suggested as a means by which complex systems emerge through neutral transitions, and has been invoked to help understand the origins of a wide variety of features from the spliceosome of eukaryotes to the interdependency and simplification widespread in microbial communities.
Today, adaptationism is associated with the "reverse engineering" approach. Richard Dawkins noted in The Blind Watchmaker that evolution, an impersonal process, produces organisms that give the appearance of having been designed for a purpose. This observation justifies looking for the function of traits observed in biological organisms. This reverse engineering is used in disciplines such as psychology and economics to explain the features of human cognition. Reverse engineering can, in particular, help explain cognitive biases as adaptive solutions that assist individuals in decision-making when considering constraints such as the cost of processing information. This approach is valuable in understanding how seemingly irrational behaviors may, in fact, be optimal given the environmental and informational limitations under which human cognition operates.
Overview
Criteria to identify a trait as an adaptation
Adaptationism is an approach to studying the evolution of form and function. It attempts to frame the existence and persistence of traits, assuming that each of them arose independently and improved the reproductive success of the organism's ancestors.
A trait is an adaptation if it fulfils the following criteria:
The trait is a variation of an earlier form.
The trait is heritable through the transmission of genes.
The trait enhances reproductive success.
Constraints on the power of evolution
Genetic constraints
Genetic reality provides constraints on the power of random mutation followed by natural selection.
With pleiotropy, some genes control multiple traits, so that adaptation of one trait is impeded by effects on other traits that are not necessarily adaptive. Selection that influences epistasis is a case where the regulation or expression of one gene, depends on one or several others. This is true for a good number of genes though to differing extents. The reason why this leads to muddied responses is that selection for a trait that is epistatically based can mean that an allele for a gene that is epistatic when selected would happen to affect others. This leads to the coregulation of others for a reason other than there is an adaptive quality to each of those traits. Like with pleiotropy, traits could reach fixation in a population as a by-product of selection for another.
In the context of development the difference between pleiotropy and epistasis is not so clear but at the genetic level the distinction is more clear. With these traits as being by-products of others it can ultimately be said that these traits evolved but not that they necessarily represent adaptations.
Polygenic traits are controlled by a number of separate genes. Many traits are polygenic, for example human height. To drastically change a polygenic trait is likely to require multiple changes.
Anatomical constraints
Anatomical constraints are features of organism's anatomy that are prevented from change by being constrained in some way. When organisms diverge from a common ancestor and inherit certain characteristics which become modified by natural selection of mutant phenotypes, it is as if some traits are locked in place and are unable to change in certain ways. Some textbook anatomical constraints often include examples of structures that connect parts of the body together though a physical link.
These links are hard if not impossible to break because evolution usually requires that anatomy be formed by small consecutive modifications in populations through generations. In his book, Why We Get Sick, Randolph Nesse uses the "blind spot" in the vertebrate eye (caused by the nerve fibers running through the retina) as an example of this. He argues that natural selection has come up with an elaborate work-around of the eyes wobbling back-and-forth to correct for this, but vertebrates have not found the solution embodied in cephalopod eyes, where the optic nerve does not interrupt the view. See also: Evolution of the eye.
Another example is the cranial nerves in tetrapods. In early vertebrate evolution, sharks, skates, and rays (collectively Chondrichthyes), the cranial nerves run from the part of the brain that interprets sensory information, and radiate out towards the organs that produce those sensations. In tetrapods, however, and mammals in particular, the nerves take an elaborate winding path through the cranium around structures that evolved after the common ancestor with sharks.
Debate with structuralism
Adaptationism is sometimes characterized by critics as an unsubstantiated assumption that all or most traits are optimal adaptations. Structuralist critics (most notably Richard Lewontin and Stephen Jay Gould in their "spandrel" paper) contend that the adaptationists have overemphasized the power of natural selection to shape individual traits to an evolutionary optimum. Adaptationists are sometimes accused by their critics of using ad hoc "just-so stories". The critics, in turn, have been accused of misrepresentation (Straw man argumentation), rather than attacking the actual statements of supposed adaptationists.
Adaptationist researchers respond by asserting that they, too, follow George Williams' depiction of adaptation as an "onerous concept" that should only be applied in light of strong evidence. This evidence can be generally characterized as the successful prediction of novel phenomena based on the hypothesis that design details of adaptations should fit a complex evolved design to respond to a specific set of selection pressures. In evolutionary psychology, researchers such as Leda Cosmides, John Tooby, and David Buss contend that the bulk of research findings that were uniquely predicted through adaptationist hypothesizing comprise evidence of the methods' validity.
Purpose and function
There are philosophical issues with the way biologists speak of function, effectively invoking teleology, the purpose of an adaptation.
Function
To say something has a function is to say something about what it does for the organism. It also says something about its history: how it has come about. A heart pumps blood: that is its function. It also emits sound, which is considered to be an ancillary side-effect, not its function. The heart has a history (which may be well or poorly understood), and that history is about how natural selection formed and maintained the heart as a pump. Every aspect of an organism that has a function has a history. Now, an adaptation must have a functional history: therefore we expect it must have undergone selection caused by relative survival in its habitat. It would be quite wrong to use the word adaptation about a trait which arose as a by-product.
Teleology
Teleology was introduced into biology by Aristotle to describe the adaptedness of organisms. Biologists have found the implications of purposefulness awkward as they suggest supernatural intention, an aspect of Plato's thinking which Aristotle rejected. A similar term, teleonomy, grew out of cybernetics and self-organising systems and was used by biologists of the 1960s such as Ernst Mayr and George C. Williams as a less loaded alternative. On the one hand, adaptation is obviously purposeful: natural selection chooses what works and eliminates what does not. On the other hand, biologists want to deny conscious purpose in evolution. The dilemma gave rise to a famous joke by the evolutionary biologist Haldane: "Teleology is like a mistress to a biologist: he cannot live without her but he's unwilling to be seen with her in public.'" David Hull commented that Haldane's mistress "has become a lawfully wedded wife. Biologists no longer feel obligated to apologize for their use of teleological language; they flaunt it. The only concession which they make to its disreputable past is to rename it 'teleonomy'."
See also
Adaptive evolution in the human genome
Beneficial acclimation hypothesis
Constructive neutral evolution
Evolutionary failure
Exaptation
Gene-centered view of evolution
Neutral theory of molecular evolution
Vitalism
References
Sources
External links
Information from "Deep Ethology" course website, by Neil Greenberg
Tooby & Cosmides comments on Maynard Smith's New York Review of Books piece on Gould et al.
Evolutionary biology
Modern synthesis (20th century) | Adaptationism | [
"Biology"
] | 2,132 | [
"Evolutionary biology"
] |
1,628,133 | https://en.wikipedia.org/wiki/Timing%20point | A timing point, time point or timepoint is a public transit stop that a vehicle tries to reach at a scheduled time. A vehicle is not supposed to pass a timepoint until the schedule time has arrived. These stops are contrasted with all other stops on a scheduled route, for which the transit agency does not explicitly schedule an arrival/departure time. These other stops occur between timepoint stops, so their scheduled times are implicitly between those of the timepoints though not explicitly defined. At minimum, it allows regular passengers to estimate when a bus would get to a stop before or after a timepoint.
The creation of digital schedules, and real-time geo-located apps has somewhat complicated the situation for agencies operating with timepoints. These apps usually ingest GTFS (General Transit Feed Specification) data, a widely used schedule data format, which often include times for every single stop on a route. Agencies may interpolate between their timepoints, but this may not reflect a realistic expectation of when a vehicle should arrive, and the GTFS specification cautions against this practice.
Whilst normal bus stops may interrupt a (painted) bike lane or a driveway may be blocked by a stopped bus, these features are not permissible for timing points. A bus bulb, where buses stop in a traffic lane, is also not suitable for a timing point.
References
Bus terminology
Scheduling (transportation) | Timing point | [
"Physics"
] | 280 | [
"Physical systems",
"Transport",
"Transport stubs"
] |
1,628,295 | https://en.wikipedia.org/wiki/Low%20Bandwidth%20X | In computing, LBX, or Low Bandwidth X, is a protocol to use the X Window System over network links with low bandwidth and high latency. It was introduced in X11R6.3 ("Broadway") in 1996, but never achieved wide use. It was disabled by default as of X.Org Server 7.1, and was removed for version 7.2.
X was originally implemented for use with the server and client on the same machine or the same local area network. By 1996, the Internet was becoming popular, and X's performance over narrow, slow links was problematic.
LBX ran as a proxy server (). It cached commonly used information — connection setup, large window properties, font metrics, keymaps and so on — and compressed data transmission over the network link.
LBX was never widely deployed as it did not offer significant speed improvements. The slow links it was introduced to help were typically insecure, and RFB (VNC) over a secure shell connection — which includes compression — proved faster than LBX, and also provided session resumption.
Finally, it was shown that greater speed improvements to X could be obtained for all networked environments with replacement of X's antiquated font system as part of the new composited graphics system, along with care and attention to application and widget toolkit design, particularly care to avoid network round trips and hence latency.
See also
Virtual Network Computing (VNC)
xmove - a tool allows you to move programs between X Window System displays
xpra - a more recent tool which is similar to xmove
NX technology, an X acceleration system
References
lbxproxy(1) (man page)
Design and Implementation of LBX: An Experiment Based Standard (.tar.gz archive file) (Keith Packard, Eighth Annual X Technical Conference, The X Resource no. 9, O'Reilly & Associates, 1994)
Broadway/Xweb FAQ (broadwayinfo.com)
The LBX mini-HOWTO v1.04 (Paul D. Smith, 11 December 1997)
An LBX Postmortem (Keith Packard)
X Window System Network Performance (Keith Packard and Jim Gettys, 2003)
Design and Implementation of the X Rendering Extension (Keith Packard, 2001
History of software
X Window System
Proxy servers
X servers
Remote desktop | Low Bandwidth X | [
"Technology"
] | 485 | [
"History of software",
"History of computing"
] |
1,628,483 | https://en.wikipedia.org/wiki/Dodecahedrane | Dodecahedrane is a chemical compound, a hydrocarbon with formula , whose carbon atoms are arranged as the vertices (corners) of a regular dodecahedron. Each carbon is bound to three neighbouring carbon atoms and to a hydrogen atom. This compound is one of the three possible Platonic hydrocarbons, the other two being cubane and tetrahedrane.
Dodecahedrane does not occur in nature and has no significant uses. It was synthesized by Leo Paquette in 1982, primarily for the "aesthetically pleasing symmetry of the dodecahedral framework".
For many years, dodecahedrane was the simplest real carbon-based molecule with full icosahedral symmetry. Buckminsterfullerene (), discovered in 1985, also has the same symmetry, but has three times as many carbons and 50% more atoms overall. The synthesis of the C20 fullerene in 2000, from brominated dodecahedrane, may have demoted to second place.
Structure
The angle between the C-C bonds in each carbon atom is 108°, which is the angle between adjacent sides of a regular pentagon. That value is quite close to the 109.5° central angle of a regular tetrahedron—the ideal angle between the bonds on an atom that has sp3 hybridisation. As a result, there is minimal angle strain. However, the molecule has significant levels of torsional strain as a result of the eclipsed conformation along each edge of the structure.
The molecule has perfect icosahedral (Ih) symmetry, as evidenced by its proton NMR spectrum in which all hydrogen atoms appear at a single chemical shift of 3.38 ppm. Unlike buckminsterfullerene, dodecahedrane has no delocalized electrons and hence has no aromaticity.
History
For over 30 years, several research groups actively pursued the total synthesis of dodecahedrane. A review article published in 1978 described the different strategies that existed up to then. The first attempt was initiated in 1964 by R.B. Woodward with the synthesis of the compound triquinacene which was thought to be able to simply dimerize to dodecahedrane. Other groups were also in the race, for example that of Philip Eaton and Paul von Ragué Schleyer.
Leo Paquette's group at Ohio State University was the first to succeed, by a complex 29-step route that mostly builds the dodecahedral skeleton one ring at a time, and finally closes the last hole.
In 1987, more versatile alternative synthesis route was found by the Horst Prinzbach's group. Their approach was based on the isomerization pagodane, obtained from isodrin (isomer of aldrin) as starting material i.a. through [6+6]photocycloaddition. Schleyer had followed a similar approach in his synthesis of adamantane.
Following that idea, joint efforts of the Prinzbach team and the Schleyer group succeeded but obtained only 8% yield for the conversion at best. In the following decade the group greatly optimized that route, so that dodecahedrane could be obtained in multi-gram quantities. The new route also made it easier to obtain derivatives with selected substitutions and unsaturated carbon-carbon bonds. Two significant developments were the discovery of σ-bishomoaromaticity and the formation of C20 fullerene from highly brominated dodecahedrane species.
Synthesis
Original route
Paquette's 1982 organic synthesis takes about 29 steps with raw materials cyclopentadiene (2 equivalents 10 carbon atoms), dimethyl acetylenedicarboxylate (4 carbon atoms) and allyltrimethylsilane (2 equivalents, 6 carbon atoms).
In the first leg of the procedure two molecules of cyclopentadiene 1 are coupled together by reaction with elemental sodium (forming the cyclopentadienyl complex) and iodine to dihydrofulvalene 2. Next up is a tandem Diels–Alder reaction with dimethyl acetylenedicarboxylate 3 with desired sequence pentadiene-acetylene-pentadiene as in symmetrical adduct 4. An equal amount of asymmetric pentadiene-pentadiene-acetylene compound (4b) is formed and discarded.
{|align="center" class="wikitable" style="font-size:small"
|
|valign=top |
|-
| Dodecahedrane synthesis part I||Dodecahedrane synthesis part II
|-
|}
In the next step of the sequence iodine is temporarily introduced via an iodolactonization of the diacid of 4 to dilactone 5. The ester group is cleaved next by methanol to the halohydrin 6, the alcohol groups converted to ketone groups in 7 by Jones oxidation and the iodine groups reduced by a zinc-copper couple in 8.
{|align="center" class="wikitable" style="font-size:small"
|
|valign=top |
|-
| Dodecahedrane synthesis part III||Dodecahedrane synthesis part IV
|-
|}
The final 6 carbon atoms are inserted in a nucleophilic addition to the ketone groups of the carbanion 10 generated from allyltrimethylsilane 9 and n-butyllithium. In the next step the vinyl silane 11 reacts with peracetic acid in acetic acid in a radical substitution to the dilactone 12 followed by an intramolecular Friedel-Crafts alkylation with phosphorus pentoxide to diketone 13. This molecule contains all required 20 carbon atoms and is also symmetrical which facilitates the construction of the remaining 5 carbon-carbon bonds.
Reduction of the double bonds in 13 to 14 is accomplished with hydrogenation with palladium on carbon and that of the ketone groups to alcohol groups in 15 by sodium borohydride. Replacement of hydroxyl by chlorine in 17 via nucleophilic aliphatic substitution takes place through the dilactone 16 (tosyl chloride). The first C–C bond forming reaction is a kind of Birch alkylation (lithium, ammonia) with the immediate reaction product trapped with chloromethyl phenyl ether, the other chlorine atom in 17 is simply reduced. This temporary appendix will in a later stage prevent unwanted enolization. The newly formed ketone group then forms another C–C bond by photochemical Norrish reaction to 19 whose alcohol group is induced to eliminate with TsOH to alkene 20.
{|align="center" class="wikitable" style="font-size:small"
|
|valign=top |
|-
| Dodecahedrane synthesis part V||Dodecahedrane synthesis part VI
|-
|}
The double bond is reduced with hydrazine and sequential diisobutylaluminum hydride reduction and pyridinium chlorochromate oxidation of 21 forms the aldehyde 22. A second Norrish reaction then adds another C–C bond to alcohol 23 and having served its purpose the phenoxy tail is removed in several steps: a Birch reduction to diol 24, oxidation with pyridinium chlorochromate to ketoaldehyde 25 and a reverse Claisen condensation to ketone 26. A third Norrish reaction produces alcohol 27 and a second dehydration 28 and another reduction 29 at which point the synthesis is left completely without functional groups. The missing C-C bond is put in place by hydrogen pressurized dehydrogenation with palladium on carbon at 250 °C to dodecahedrane 30.
Pagodane route
In Prinzbach's optimized route from pagodane to dodecahedrane, the original low-yielding isomerization of parent pagodane to dodecahedrane is replaced by a longer but higher yielding sequence - which nevertheless still relies heavily on pagodane derivatives. In the scheme below, the divergence from the original happens after compound 16.
Derivatives
A variety of dodecahedrane derivatives have been synthesized and reported in the literature.
Hydrogen substitution
Substitution of all 20 hydrogens by fluorine atoms yields the relatively unstable perfluorododecahedrane C20F20, which was obtained in milligram quantities. Trace amounts of the analogous perchlorododecahedrane C20Cl20 were obtained, among other partially chlorinated derivatives, by reacting dissolved in liquid chlorine under pressure at about 140 °C and under intense light for five days. Complete replacement by heavier halogens seems increasingly difficult due to their larger size. Half or more of the hydrogen atoms can be substituted by hydroxyl groups to yield polyols, but the extreme compound C20(OH)20 remained elusive as of 2006. Amino-dodecahedranes comparable to amantadine have been prepared, but were more toxic and with weaker antiviral effects.
Annulated dodecahedrane structures have been proposed.
Encapsulation
Molecules whose framework forms a closed cage, like dodecahedrane and buckminsterfullerene, can encapsulate atoms and small molecules in the hollow space within. Those insertions are not chemically bonded to the caging compound, but merely mechanically trapped in it.
Cross, Saunders and Prinzbach succeeded in encapsulating helium atoms in dodecahedrane by shooting He+ ions at a film of the compound. They obtained microgram quantities of (the "@" being the standard notation for encapsulation), which they described as a quite stable substance. The molecule has been described as "the world's smallest helium balloon".
References
External links
Paquette's dodecahedrane synthesis at SynArchive.com
2D and 3D models of dodecahedrane and cuneane assemblies
Full text of Paquette's paper
Polycyclic nonaromatic hydrocarbons
Total synthesis
Cyclopentanes
Substances discovered in the 1980s | Dodecahedrane | [
"Chemistry"
] | 2,087 | [
"Total synthesis",
"Chemical synthesis"
] |
1,628,580 | https://en.wikipedia.org/wiki/Bomb%20%28icon%29 | The bomb icon (💣) has several different applications in computing, and typically indicates a fatal system error.
In computing
Mac OS
The bomb icon in Mac OS is a symbol designed by Susan Kare that was displayed inside the System Error alert box when the "classic" Macintosh operating system had a crash which the system decided was unrecoverable. Since the classic Mac OS offered no memory protection, an application crash would often take down the entire system.
The bomb symbol first appeared on the original Macintosh in 1984. Often, a reason for the crash, including the error code, was displayed in the dialog. In some cases, a "Resume" button would be available, allowing the user to dismiss the dialog and force the offending program to quit, but most often the resume button would be disabled and the computer would have to be restarted. Originally, the resume button was unavailable unless the running program had provided the OS with code to allow recovery. With the advent of System 7, if the OS thought it could handle recovery, a normal error dialog box was displayed, and the application was forced to quit. This was helped by the classic Mac OS providing a little bit of protection against heap corruption using guard pages; if the application was to crash and the application's heap was corrupt, it could be thrown away.
The debugger program MacsBug was sometimes used even by end users to provide basic (though not always reliable) error recovery, and could be used for troubleshooting purposes, much as the output of a Unix kernel panic or a Windows NT Blue Screen of Death could be. Mac OS Classic bomb boxes were often ridiculed for providing little or no useful information about the error, presenting only information such as "System Error 11" or "address error"; this was a conscious decision by the Macintosh team to eliminate any information that the end user could not make sense of. The error code was intended to be included in a bug report to the developer.
In Mac OS X, being based on BSD's UNIX-like kernel, the system architecture is vastly different from that in the classic Mac OS, and an application crash cannot usually bring down the entire system. A kernel panic screen (either text overwritten on the screen in older versions, or simplified to a reboot message in more recent versions) replaces the bomb symbol but appears less often due to the radically different system architecture. The bomb symbol is not used in Mac OS X, but a test application called Bomb.app, specifically written to cause a non-fatal crash, is included with Xcode and uses a rendition of the bomb symbol as its icon.
In the original Mac OS, the system call to display a "bomb box" was called DSError, for "Deep Shit". This was deemed obscene, and became the "System Error Manager".
Atari ST TOS
TOS-based systems, such as the Atari ST, used a row of bombs to indicate a critical system error. The number of bombs displayed revealed information about the occurred error. The error (also called an exception) is reported by the Motorola 68000 microprocessor. The first version of TOS used mushroom clouds.
1 bomb: Reset, Initial PC2
2 bombs: Bus Error
3 bombs: Address Error
4 bombs: Illegal Instruction
5 bombs: Division by zero
6 bombs: CHK Instruction
7 bombs: TRAPV Instruction
8 bombs: Privilege Violation
9 bombs: Trace
10 bombs: Line 1010 Emulator
11 bombs: Line 1111 Emulator
12–13 bombs: Reserved
14 bombs: Format Error
15 bombs: Uninitialized Interrupt Vector
16–23 bombs: Reserved
24 bombs: Spurious Interrupt
25 bombs: Level 1 Interrupt Autovector
26 bombs: Level 2 Interrupt Autovector
27 bombs: Level 3 Interrupt Autovector
28 bombs: Level 4 Interrupt Autovector
29 bombs: Level 5 Interrupt Autovector
30 bombs: Level 6 Interrupt Autovector
31 bombs: Level 7 Interrupt Autovector
32–47 bombs: Trap Instruction Vectors
48–63 bombs: Reserved
64–255 bombs: User Interrupt Vectors
Unicode
Bomb emoji was added to Miscellaneous Symbols and Pictographs character block in Unicode version 6.0 with code point .
See also
Grenade (insignia)
Screen of death
References
External links
About the System Error Handler
Computer errors
Macintosh operating systems user interface
Atari ST
Screens of death | Bomb (icon) | [
"Technology"
] | 886 | [
"Computer errors",
"Screens of death"
] |
1,628,643 | https://en.wikipedia.org/wiki/GM-1 | GM-1 (Göring Mischung 1) was a system for injecting nitrous oxide into aircraft engines that was used by the Luftwaffe in World War II. This increased the amount of oxygen in the fuel mixture, and thereby improved high-altitude performance. GM-1 was used on several modifications of existing fighter designs to counter the increasing performance of Allied fighters at higher altitudes.
A different system for low-altitude boost known as MW 50 was also used, although GM-1 and MW 50 were rarely used on the same engine. MW-50 injected a methanol-water mixture into the cylinders to cool the mix. Cooling causes the air to become denser, therefore allowing more air into each cylinder for a given volume. This is the same principle that intercoolers use.
GM-1 was developed in 1940 by Otto Lutz to improve high-altitude performance. It could be used by fighters, destroyers, bombers and reconnaissance aircraft, though its first use was in the Bf 109E/Z fighter. Originally, it was liquified under high pressure and stored in several high-pressure vessels until it was found that low-temperature liquefied nitrous oxide gave better performance due to improved charge cooling. It could also be stored and handled more conveniently and was less vulnerable to enemy fire.
GM-1 was typically sprayed in liquid form directly into the supercharger intake from two jets of different bore while at the same time, the fuel flow was increased to take advantage of the additional oxygen from the nitrous oxide. The jets could be operated individually or in combination, yielding three steps of power increase, for example 120/240/360 HP at different GM-1 flow rates (60, 100 and 150 grams/sec). The development of a continuously variable injection system was considered, but apparently it never saw operational use.
Initially intended as standard equipment for the Luftwaffe, in operational service it was found that GM-1 had some drawbacks. The additional weight of the equipment reduced performance on all missions, while the system was only used in the cases where the aircraft went to very high altitudes. GM-1 also became less attractive than originally imagined when in 1943, the previous trend towards ever increasing combat altitudes ended.
While GM-1 saw little use in the second half of the war, the Focke-Wulf Ta 152H, which had been developed as a dedicated high-altitude interceptor, also received a GM-1 system to provide it with superior performance at high altitude. The Ta 152H was one of the few designs to support both GM-1 and MW 50.
Similar systems have been used in racing cars and hot rods.
See also
Nitrous oxide engine
Citations
Bibliography
External links
Messerschmitt Bf 109 Site - Short Operating Manual for pilots and ground personnel for the GM-1 system in the Bf 109 G (In German).
Aircraft engines | GM-1 | [
"Technology"
] | 590 | [
"Engines",
"Aircraft engines"
] |
1,629,041 | https://en.wikipedia.org/wiki/Filter%20funnel | A filter funnel is a laboratory funnel used for separating solids from liquids via the laboratory process of filtering.
In order to achieve this, a cone-like shaped piece of filter paper is usually folded into a cone and placed within the funnel. The suspension of solid and liquid is then poured through the funnel. The solid particles are too large to pass through the filter paper and are left on the paper, while the much smaller liquid molecules pass through the paper to a vessel positioned below the funnel, producing a filtrate. The filter paper is used only once. If only the liquid is of interest, the paper is discarded; if the suspension is of interest, both the solid residue and non-polar liquids, such as oil, may clog of polyethylene or galvanized steel and using a brass or plastic mesh filter, are typically for automotive and workshop use, to filter debris from fuel, lubricating oil and coolant. The screen is reusable, and may be cleaned by inverting the funnel and tapping it on a hard surface, or popping it out and washing it separately. This helps to avoid spilling any liquids.
References
Laboratory equipment
Water filters | Filter funnel | [
"Chemistry"
] | 238 | [
"Water treatment",
"Water filters",
"Filters"
] |
1,629,074 | https://en.wikipedia.org/wiki/Magic%20hexagon | A magic hexagon of order n is an arrangement of numbers in a centered hexagonal pattern with n cells on each edge, in such a way that the numbers in each row, in all three directions, sum to the same magic constant M. A normal magic hexagon contains the consecutive integers from 1 to 3n2 − 3n + 1. Normal magic hexagons exist only for n = 1 (which is trivial, as it is composed of only 1 cell) and n = 3. Moreover, the solution of order 3 is essentially unique. Meng gives a less intricate constructive proof.
The order-3 magic hexagon has been published many times as a 'new' discovery. An early reference, and possibly the first discoverer, is Ernst von Haselberg (1887).
Proof of normal magic hexagons
The numbers in the hexagon are consecutive, and run from 1 to . Hence their sum is a triangular number, namely
There are r = 2n − 1 rows running along any given direction (E-W, NE-SW, or NW-SE). Each of these rows sum up to the same number M. Therefore:
This can be rewritten as
Multiplying throughout by 32 gives
which shows that must be an integer, hence 2n − 1 must be a factor of 5, namely 2n − 1 = ±1 or 2n − 1 = ±5. The only that meet this condition are and , proving that there are no normal magic hexagons except those of order 1 and 3.
Abnormal magic hexagons
Although there are no normal magical hexagons with order greater than 3, certain abnormal ones do exist. In this case, abnormal means starting the sequence of numbers other than with 1. Arsen Zahray discovered these order 4 and 5 hexagons:
The order 4 hexagon starts with 3 and ends with 39, its rows summing to 111. The order 5 hexagon starts with 6 and ends with 66 and sums to 244.
An order 5 hexagon starting with 15, ending with 75 and summing to 305 is this:
A higher sum than 305 for order 5 hexagons is not possible.
Order 5 hexagons, where the "X" are placeholders for order 3 hexagons, which complete the number sequence. The left one contains the hexagon with the sum 38 (numbers 1 to 19) and the right one, one of the 26 hexagons with the sum 0 (numbers −9 to 9). For more informations visit the German Wikipedia article.
An order 6 hexagon can be seen below. It was created by Louis Hoelbling, October 11, 2004:
It starts with 21, ends with 111, and its sum is 546.
This magic hexagon of order 7 was discovered using simulated annealing by Arsen Zahray on 22 March 2006:
It starts with 2, ends with 128 and its sum is 635.
An order 8 magic hexagon was generated by Louis K. Hoelbling on February 5, 2006:
It starts with −84 and ends with 84, and its sum is 0.
An order 9 magic hexagon was found by Klaus Meffert on September 10, 2024 with help of an AI:
It starts with -108 and ends with 108, and its sum is 0. The solution was found by a python program that was created by the author, utilizing an AI for critical parts of the code.
Magic T-hexagons
Hexagons can also be constructed with triangles, as the following diagrams show.
This type of configuration can be called a T-hexagon and it has many more properties than the hexagon of hexagons.
As with the above, the rows of triangles run in three directions and there are 24 triangles in a T-hexagon of order 2. In general, a T-hexagon of order n has triangles. The sum of all these numbers is given by:
If we try to construct a magic T-hexagon of side n, we have to choose n to be even, because there are rows so the sum in each row must be
For this to be an integer, n has to be even. To date, magic T-hexagons of order 2, 4, 6 and 8 have been discovered. The first was a magic T-hexagon of order 2, discovered by John Baker on 13 September 2003. Since that time, John has been collaborating with David King, who discovered that there are 59,674,527 non-congruent magic T-hexagons of order 2.
Magic T-hexagons have a number of properties in common with magic squares, but they also have their own special features. The most surprising of these is that the sum of the numbers in the triangles that point upwards is the same as the sum of those in triangles that point downwards (no matter how large the T-hexagon). In the above example,
Notes
References
Baker. J. E. and King, D. R. (2004) "The use of visual schema to find properties of a hexagon" Visual Mathematics, Volume 5, Number 3
Baker, J. E. and Baker, A. J. (2004) "The hexagon, nature's choice" Archimedes, Volume 4
See also
Hexagonal tortoise problem
Magic hexagram
Magic figures | Magic hexagon | [
"Mathematics"
] | 1,135 | [
"Recreational mathematics",
"Magic figures",
"Combinatorics"
] |
1,629,311 | https://en.wikipedia.org/wiki/Iterative%20design | Iterative design is a design methodology based on a cyclic process of prototyping, testing, analyzing, and refining a product or process. Based on the results of testing the most recent iteration of a design, changes and refinements are made. This process is intended to ultimately improve the quality and functionality of a design. In iterative design, interaction with the designed system is used as a form of research for informing and evolving a project, as successive versions, or iterations of a design are implemented.
History
Iterative design has long been used in engineering fields. One example is the plan–do–check–act cycle implemented in the 1960s. Most New product development or existing product improvement programs have a checking loop which is used for iterative purposes. DMAIC uses the Six Sigma framework and has such a checking function.
Object-Oriented Programming
Iterative design is connected with the practice of object-oriented programming, and the phrase appeared in computer science literature as early as 1990. The idea has its roots in spiral development, conceived of by Barry Boehm.
Iterative design process
The iterative design process may be applied throughout the new product development process. However, changes are easiest and less expensive to implement in the earliest stages of development. The first step in the iterative design process is to develop a prototype. The prototype should be evaluated by a focus group or a group not associated with the product in order to deliver non-biased opinions. Information from the focus group should be synthesized and incorporated into the next iteration of the design. The process should be repeated until user issues have been reduced to an acceptable level.
Application: Human computer interfaces
Iterative design is commonly used in the development of human computer interfaces. This allows designers to identify any usability issues that may arise in the user interface before it is put into wide use. Even the best usability experts cannot design perfect user interfaces in a single attempt, so a usability engineering lifecycle should be built around the concept of iteration.
The typical steps of iterative design in user interfaces are as follows:
Complete an initial interface design
Present the design to several test users
Note any problems had by the test user
Refine interface to account for/fix the problems
Repeat steps 2-4 until user interface problems are resolved
Iterative design in user interfaces can be implemented in many ways. One common method of using iterative design in computer software is software testing. While this includes testing the product for functionality outside of the user interface, important feedback on the interface can be gained from subject testing early versions of a program. This allows software companies to release a better quality product to the public, and prevents the need of product modification following its release.
Iterative design in online (website) interfaces is a more continual process, as website modification, after it has been released to the user, is far more viable than in software design. Often websites use their users as test subjects for interface design, making modifications based on recommendations from visitors to their sites.
Iterative design use
Iterative design is a way of confronting the reality of unpredictable user needs and behaviors that can lead to sweeping and fundamental changes in a design. User testing will often show that even carefully evaluated ideas will be inadequate when confronted with a user test. Thus, it is important that the flexibility of the iterative design's implementation approach extends as far into the system as possible. Designers must further recognize that user testing results may suggest radical change that requires the designers to be prepared to completely abandon old ideas in favor of new ideas that are more equipped to suit user needs. Iterative design applies in many fields, from making knives to rockets. As an example consider the design of an electronic circuit that must perform a certain task, and must ultimately fit in a small space on a circuit board. It is useful to split these independent tasks into two smaller and simpler tasks, the functionality task, and the space and weight task. A breadboard is a useful way of implementing the electronic circuit on an interim basis, without having to worry about space and weight.
Once the circuit works, improvements or incremental changes may be applied to the breadboard to increase or improve functionality over the original design. When the design is finalized, one can set about designing a proper circuit board meeting the space and weight criteria. Compacting the circuit on the circuit board requires that the wires and components be juggled around without changing their electrical characteristics. This juggling follows simpler rules than the design of the circuit itself, and is often automated. As far as possible off the shelf components are used, but where necessary for space or performance reasons, custom made components may be developed.
Several instances of iterative design are as follows:
Wiki: A wiki is a natural repository for iterative design. The 'Page History' facility allows tracking back to prior versions. Modifications are mostly incremental, and leave substantial parts of the text unchanged.
Common law: The principle of legal precedent builds on past experience. This makes law a form of iterative design where there should be a clear audit trail of the development of legal thought.
Evolution: There is a parallel between iterative and the theory of natural Selection. Both involve a trial and error process in which the most suitable design advances to the next generation, while less suitable designs perish by the wayside. Subsequent versions of a product should also get progressively better as its producers learn what works and what doesn't in a process of refinement and continual improvement.
Fast prototyping tools
One approach to iterative design is to use the highest level of abstraction for developing an early generation product. The principle here is that rapid development may not produce efficient code, but obtaining feedback is more important than technology optimization. Examples of this approach include use of non-functional code, object databases, or low code platforms - these allow quick testing of designs before issues of optimization are addressed.
Benefits
When properly applied, iterative design will ensure a product or process is the best solution possible. When applied early in the development stage, significant cost savings are possible.
Other benefits to iterative design include:
Serious misunderstandings are made evident early in the lifecycle, when it's possible to react to them.
It enables and encourages user feedback, so as to elicit the system's real requirements.
Where the work is contracted, Iterative Design provides an incremental method for more effectively involving the client in the complexities that often surround the design process.
The development team is forced to focus on those issues that are most critical to the project, and team members are shielded from those issues that distract and divert them from the project's real risks.
Continual testing enables an objective assessment of the project's status.
Inconsistencies among requirements, designs, and implementations are detected early.
The workload of the team, especially the testing team, is spread out more evenly throughout the lifecycle.
This approach enables the team to leverage lessons learned, and therefore to continually improve the process.
Stakeholders in the project can be given concrete evidence of the project's status throughout the lifecycle.
Marshmallow Challenge
The Marshmallow Challenge is an instructive design challenge. It involves the task of constructing the highest possible free-standing structure with a marshmallow on top. The structure must be completed within 18 minutes using only 20 sticks of spaghetti, one yard of tape, and one yard of string.
Observation and studies of participants show that kindergartners are regularly able to build higher structures, in comparison to groups of business school graduates. This is explained by the tendency for children to at once stick the marshmallow on top of a simple structure, test the prototype, and continue to improve upon it. Whereas, business school students tend to spend time vying for power, planning, and finally producing a structure to which the marshmallow is added. The challenge helps to build and develop prototyping, teamwork, leadership and innovation skills and is a popular STEM activity. The challenge was invented by Peter Skillman of Palm, Inc. and popularized by Tom Wujec of Autodesk.
See also
Disruptive innovation
Extreme programming
Spiral model
Top-down and bottom-up design
Paper prototyping
Scrum (software development)
References
Boehm, Barry W. (May 1988) "A Spiral Model of Software Development and Enhancement," Computer, IEEE, pp. 61–72.
Gould, J.D. and Lewis, C. (1985). Designing for Usability: Key Principles and What Designers Think, Communications of the ACM, March, 28(3), 300–311.
Kruchten, Philippe. The Rational Unified Process—An Introduction,
External links
Iterative User Interface Design at useit.com
Association for Computing Machinery
Marshmallow Challenge official website
TED video on Marshmallow Challenge
Classroom images of Marshmallow Challenge
Design
Systems engineering | Iterative design | [
"Engineering"
] | 1,791 | [
"Systems engineering",
"Design"
] |
1,629,320 | https://en.wikipedia.org/wiki/Attenuation%20length | In physics, the attenuation length or absorption length is the distance into a material when the probability has dropped to that a particle has not been absorbed. Alternatively, if there is a beam of particles incident on the material, the attenuation length is the distance where the intensity of the beam has dropped to , or about 63% of the particles have been stopped.
Mathematically, the probability of finding a particle at depth into the material is calculated by the Beer–Lambert law:
.
In general is material- and energy-dependent.
See also
Beer's Law
Mean free path
Attenuation coefficient
Attenuation (electromagnetic radiation)
Radiation length
References
https://web.archive.org/web/20050215215652/http://www.ct.infn.it/~rivel/Glossario/node2.html
External links
http://henke.lbl.gov/optical_constants/atten2.html
Particle physics
Experimental particle physics | Attenuation length | [
"Physics"
] | 207 | [
"Particle physics stubs",
"Experimental physics",
"Particle physics",
"Experimental particle physics"
] |
1,629,349 | https://en.wikipedia.org/wiki/Catechol | Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is an organic compound with the molecular formula . It is the ortho isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It was first discovered by destructive distillation of the plant extract catechin. About 20,000 tonnes of catechol are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances. Small amounts of catechol occur in fruits and vegetables.
Isolation and synthesis
Catechol was first isolated in 1839 by Edgar Hugo Emil Reinsch (1809–1884) by distilling it from the solid tannic preparation catechin, which is the residuum of catechu, the boiled or concentrated juice of Mimosa catechu (Acacia catechu). Upon heating catechin above its decomposition point, a substance that Reinsch first named Brenz-Katechusäure (burned catechu acid) sublimated as a white efflorescence. This was a thermal decomposition product of the flavanols in catechin. In 1841, both Wackenroder and Zwenger independently rediscovered catechol; in reporting on their findings, Philosophical Magazine coined the name pyrocatechin. By 1852, Erdmann realized that catechol was benzene with two oxygen atoms added to it; in 1867, August Kekulé realized that catechol was a diol of benzene, so by 1868, catechol was listed as pyrocatechol. In 1879, the Journal of the Chemical Society recommended that catechol be called "catechol", and in the following year, it was listed as such.
Catechol has since been shown to occur in free form naturally in kino and in beechwood tar. Its sulfonic acid has been detected in the urine of horses and humans.
Catechol is produced industrially by the hydroxylation of phenol using hydrogen peroxide.
It can be produced by reaction of salicylaldehyde with base and hydrogen peroxide (Dakin oxidation), as well as the hydrolysis of 2-substituted phenols, especially 2-chlorophenol, with hot aqueous solutions containing alkali metal hydroxides. Its methyl ether derivative, guaiacol, converts to catechol via hydrolysis of the bond as promoted by hydroiodic acid (HI).
Reactions
Like some other difunctional benzene derivatives, catechol readily condenses to form heterocyclic compounds. For example, using phosphorus trichloride or phosphorus oxychloride gives the cyclic chlorophosphonite or chlorophosphonate, respectively; sulfuryl chloride gives the sulfate; and phosgene () gives the carbonate:
where X = PCl or POCl; ; CO
Basic solutions of catechol react with iron(III) to give the red . Ferric chloride gives a green coloration with the aqueous solution, while the alkaline solution rapidly changes to a green and finally to a black color on exposure to the air. Iron-containing dioxygenase enzymes catalyze the cleavage of catechol.
Redox chemistry
Catechols convert to the semiquinone radical. At , this conversion occurs at 100 mV:
The semiquinone radical can be reduced to the catecholate dianion, the potential being dependent on pH:
Catechol is produced by a reversible two-electron, two-proton reduction of 1,2-benzoquinone ( vs SHE; vs SHE).
The redox series catecholate dianion, monoanionic semiquinonate, and benzoquinone are collectively called dioxolenes. Dioxolenes can function as ligands for metal ions.
Catechol derivatives
Catechol derivatives are found widely in nature. They often arise by hydroxylation of phenols.
Arthropod cuticle consists of chitin linked by a catechol moiety to protein. The cuticle may be strengthened by cross-linking (tanning and sclerotization), in particular, in insects, and of course by biomineralization.
The synthetic derivative 4-tert-butylcatechol is used as an antioxidant and polymerization inhibitor.
Uses
Approximately 50% of the synthetic catechol is consumed in the production of pesticides, the remainder being used as a precursor to fine chemicals such as perfumes and pharmaceuticals. It is a common building block in organic synthesis. Several industrially significant flavors and fragrances are prepared starting from catechol. Guaiacol is prepared by methylation of catechol and is then converted to vanillin on a scale of about 10M kg per year (1990). The related monoethyl ether of catechol, guethol, is converted to ethylvanillin, a component of chocolate confectioneries. 3-trans-Isocamphylcyclohexanol, widely used as a replacement for sandalwood oil, is prepared from catechol via guaiacol and camphor. Piperonal, a flowery scent, is prepared from the methylene diether of catechol followed by condensation with glyoxal and decarboxylation.
Josef Maria Eder published in 1879 his findings on the use of catechol as a black-and-white photographic developer, but, except for some special purpose applications, its use is largely historical. It is rumored to have been used briefly in Eastman Kodak's HC-110 developer and is rumored to be a component in Tetenal's Neofin Blau developer. It is a key component of Finol from Moersch Photochemie in Germany. Modern catechol developing was pioneered by noted photographer Sandy King. His "PyroCat" formulation is popular among modern black-and-white film photographers. King's work has since inspired further 21st-century development by others such as Jay De Fehr with Hypercat and Obsidian Acqua developers, and others.
Nomenclature
Although rarely encountered, the officially "preferred IUPAC name" (PIN) of catechol is benzene-1,2-diol. The trivial name pyrocatechol is a retained IUPAC name, according to the 1993 Recommendations for the Nomenclature of Organic Chemistry.
See also
Enol
Pyrogallol
Thiotimoline
References
External links
International Chemical Safety Card 0411
NIOSH Pocket Guide to Chemical Hazards
IARC Monograph: "Catechol"
IUPAC Nomenclature of Organic Chemistry (online version of the "Blue Book")
Antioxidants
Chelating agents
Enediols
IARC Group 2B carcinogens
Photographic chemicals
Reducing agents
Substances discovered in the 19th century | Catechol | [
"Chemistry"
] | 1,446 | [
"Chelating agents",
"Redox",
"Process chemicals",
"Reducing agents"
] |
1,629,461 | https://en.wikipedia.org/wiki/Radiation%20length | In particle physics, the radiation length is a characteristic of a material, related to the energy loss of high energy particles electromagnetically interacting with it. It is defined as the mean length (in cm) into the material at which the energy of an electron is reduced by the factor 1/e.
Definition
In materials of high atomic number (e.g. tungsten, uranium, plutonium) the electrons of energies >~10 MeV predominantly lose energy by , and high-energy photons by pair production. The characteristic amount of matter traversed for these related interactions is called the radiation length , usually measured in g·cm−2. It is both the mean distance over which a high-energy electron loses all but of its energy by , and of the mean free path for pair production by a high-energy photon. It is also the appropriate length scale for describing high-energy electromagnetic cascades.
The radiation length for a given material consisting of a single type of nucleus can be approximated by the following expression:
where is the atomic number and is mass number of the nucleus.
For , a good approximation is
.
where
is the number density of the nucleus,
denotes the reduced Planck constant,
is the electron rest mass,
is the speed of light,
is the fine-structure constant.
For electrons at lower energies (below few tens of MeV), the energy loss by ionization is predominant.
While this definition may also be used for other electromagnetic interacting particles beyond leptons and photons, the presence of the stronger hadronic and nuclear interaction makes it a far less interesting characterisation of the material; the nuclear collision length and nuclear interaction length are more relevant.
Comprehensive tables for radiation lengths and other properties of materials are available from the Particle Data Group.
See also
Mean free path
Attenuation length
Attenuation coefficient
Attenuation
Range (particle radiation)
Stopping power (particle radiation)
Electron energy loss spectroscopy
References
Experimental particle physics | Radiation length | [
"Physics"
] | 391 | [
"Particle physics stubs",
"Experimental physics",
"Particle physics",
"Experimental particle physics"
] |
1,629,574 | https://en.wikipedia.org/wiki/National%20Ocean%20Sciences%20Bowl | The National Ocean Sciences Bowl (NOSB) is a national high-school science competition currently hosted by the Center for Ocean Leadership, a University Corporation for Atmospheric Research Community Program beginning 10/3/2022. It follows a quiz-bowl format, with lockout buzzers and extended team challenge questions to test students on their knowledge of oceanography. Questions cover the fields of biology, chemistry, geology, geography, social science, technology, and physics. The purpose of the event is to increase knowledge of the ocean among high school students and, ultimately, magnify public understanding of ocean research.
The annual competition was first held in 1998, the International Year of the Ocean. Twenty-five U.S. regions compete in the NOSB, each with its own regional competitions. The regional competitions are coordinated by Regional Coordinators, who are typically affiliated with a university in their region. Each year, approximately 2,000 students from 300 schools across the nation compete for prizes and a trip to the national competition. Students who participate are eligible to apply for the National Ocean Scholar Program.
The NOSB is a creation of oceanographer Rick Spinrad and Admiral James D. Watkins, USN Ret.
Format and scoring
Types of questions
Toss-up: These are multiple choice questions that can be answered by any of the 4 active players on either team in play. Teams have 5 seconds to buzz in and answer the question. If the first team's answer is incorrect, the opposing team will get another 5 seconds to answer. The team that buzzes in first gets to answer the question. A correct answer wins the team 4 points and the right to attempt a bonus question. No conferring is allowed on toss-ups. If a player buzzes in before a moderator finishes reading the question, the buzz is called an interrupt. An incorrect answer will cause the team to lose 4 points and the question to be re-read to the opposing team. This is the only situation in which a team can lose points. However, no points are lost for incorrect answers that are not interrupts. If a player begins an answer before being verbally recognized by the moderator, this is called a blurt. The answer is ignored (not indicated correct or incorrect by the moderator) and the question is re-read to the opposing team. There is no point penalty for a blurt, but the team that blurted is disqualified from answering that question.
Bonus: These are short answer questions that only the team that correctly answered the previous toss-up may answer. Teams have 20 seconds to confer and answer this question. The team captain must begin the team's answer before time is called. A correct response is awarded with an additional 6 points.
Team Challenge Question (TCQ): Each Team Challenge Question is a multi-part question worth up to 20 points, with partial credits possible. Time ranges from 2 to 5 minutes for a team challenge question, and the topics can be anything related to oceanography.
A single NOSB match consists of two 6-minute buzzer segments with two Team Challenge Questions in between. Each round is made up of 20 question pairs. After the break, the second half begins with the first toss-up that was not read in the first half and continues until time expires or all questions have been read. The most points a team can earn each round is 240 points (20 toss-ups and bonuses each plus full-credit on the two TCQs), but earning 100 or more points is considered very impressive. Teams may make substitutions only during the break.
With the exception of articles such as "a","an", and "the", answers to toss-up, multiple-choice questions must be exactly as those on the written page. Prefacing answers with phrases such as "My answer is" is not acceptable for toss-up questions.
Science Expert Briefing (SEB)
The SEB is a mock congressional hearing where students present science recommendations on a piece of legislation, enhancing the critical thinking elements of the competition and focusing on real-world skills. Regional bowl winners must participate in the SEB to be eligible for in-person national finals.
Roles of Officials
Moderator: Reads questions and interprets responses by comparing with the answer sheet.
Science Judge: If the official answer is challenged by a team, the moderator may consult the Science Judge to come to a verdict.
Rules Judge: Oversees activity in the event room and addresses any issues or misbehavior.
Scorekeeper: Records the current score of a progressing match, including rewards and penalties. Generally a copy is saved for later reference.
Timekeeper: Tracks the time throughout the round. In charge of stopping, starting, and resetting the clock. Also notifies teams of time benchmarks (such as 5 seconds left to answer a bonus or 45 and 15 seconds left to answer a Team Challenge Question).
Runner: Primarily used for retrieving documents, such as the official testing material. Also brings Team Challenge Questions to and from the grading center for official scoring.
Locations
The National competition is held in one of the participating colleges that holds a regional bowl. These colleges draw from high schools in their areas and run the regional competitions, often naming the regional according to the characteristics of the region. For example, the region encompassing Colorado and the surrounding area is called the "Trout Bowl." The annual themes, since 2008, are also listed below.
Nationals
2023 & 2024 - None took place.
2022- Virtual - Climate Change: Ocean Science and Solutions
2021- Virtual - Plunging into Our Polar Seas
2020- Virtual - Understanding Human, Economic and Environmental Resiliency in the Gulf of Mexico
2019- Washington, DC - Observe the Ocean, Secure the Future
2018- Boulder, Colorado - Our Ocean Shaping Weather
2017- Corvallis, Oregon - Blue Energy: Powering the Planet With Our Ocean
2016- Morehead City, North Carolina - Our Changing Ocean: Science for Strong Coastal Communities
2015- Ocean Springs, Mississippi - The Science of Oil in the Ocean
2014- Seattle, Washington - Ocean Acidification
2013- Milwaukee, Wisconsin - The Great Lakes: A Window into Freshwater Science
2012- Baltimore, Maryland - Sea of Change: Development and Evolution
2011- Galveston, Texas - Human Responses to Ocean Events
2010- St. Petersburg, Florida - Marine Technology
2009- Washington, DC - Biodiversity
2008- Seward, Alaska - International Polar Year
2007- Long Island, New York
2006- Pacific Grove, California
2005- Biloxi, Mississippi
2004- Charleston, South Carolina
2003- LaJolla, California
2002- Providence, Rhode Island
2001- Miami, Florida
2000- Linthicum, Maryland
1999- Washington, DC
1998- Washington, DC
Regionals
Aloha Bowl (University of Hawaiʻi at Mānoa)
Bay Scallop Bowl (People Making a Difference)
Blue Crab Bowl (Virginia Institute of Marine Science)
Blue Heron Bowl (University of North Carolina Institute of Marine Sciences and Seahorse Coastal Consulting)
Blue Lobster Bowl (MIT Department of Earth, Atmospheric & Planetary Sciences and People Making a Difference)
Chesapeake Bay Bowl (George Mason University)
The Dolphin Challenge (Texas A&M University - Galveston)
Garibaldi Bowl (University of San Diego) (formerly Grunion Bowl)
Great Lakes Bowl (University of Michigan)
Hurricane Bowl (Gulf Coast Research Laboratory Marine Education Center)
Lake Sturgeon Bowl (University of Wisconsin–Milwaukee)
Loggerhead Challenge (University of Texas Marine Science Institute - Port Aransas)
Los Angeles Surf Bowl (Jet Propulsion Laboratory)
Manatee Bowl (Florida Atlantic University: Harbor Branch Oceanographic Institute)
Nor'easter Bowl (University of New England)
Orca Bowl (University of Washington)
Penguin Bowl (Pittsburgh Zoo & PPG Aquarium)
Quahog Bowl (Connecticut Sea Grant & Project Oceanology)
Salmon Bowl (Oregon State University)
Sea Lion Bowl (California State University, Monterey Bay) (formerly Otter Bowl)
Shore Bowl (People Making a Difference)
Southern Stingray Bowl (Savannah State University)
Sponge Bowl (People Making a Difference)
Spoonbill Bowl (University of South Florida)
Trout Bowl (National Renewable Energy Laboratory)
Tsunami Bowl (University of Alaska-Fairbanks)
Results of the national competition
Schools with greatest number of wins
5: Lexington High School (1998-2002)
4: Marshfield High School (2009-2012)
2: Albany High School (2016, 2019)
2: Boise High School (2014-2015)
2: Lincoln-Sudbury Regional High School (2006, 2008)
2: Cranston High School West (Cranston, Rhode Island) (2003, 2005)
1: Canyon Crest Academy (2022)
1: Dougherty Valley High School (2021)
1: Ladue Horton Watkins High School (2020)
1: Montgomery Blair High School (2018)
1: Santa Monica High School (2017)
1: Arcadia High School (2013)
1: Contoocook Valley Regional High School (2007)
1: Mission San Jose High School (2004)
Top-placing teams at the 2022 National Ocean Sciences Bowl (the third year of virtual competition):
Canyon Crest Academy
Dougherty Valley High School
Lexington High School
Tesla STEM High School
Ladue Horton Watkins High School
Midwood High School
Santa Monica High School
Thomas Jefferson High School for Science and Technology
Top-placing teams at the 2021 National Ocean Sciences Bowl (the second year of virtual competition):
Dougherty Valley High School
Lexington High School
Canyon Crest Academy
Santa Monica High School
Tesla STEM High School
Saline High School
Oxford High School
E. O. Smith High School
Top-placing teams at the 2020 National Ocean Sciences Bowl (the 2020 competition was the first-ever virtual finals competition):
Ladue Horton Watkins High School
Santa Monica High School
Dougherty Valley High School
Centerville High School
West Windsor-Plainsboro High School North
Newport High School
Lexington High School
Arkansas School for Mathematics, Sciences, and the Arts
Top-placing teams at the 2019 National Ocean Sciences Bowl:
Albany High School
Santa Monica High School
Ladue Horton Watkins High School
Centerville High School
Marine Academy of Science and Technology
Oregon Coast Aquarium (Newport, Oregon)
Newport High School
Science and Technology Magnet High School of Southeastern Connecticut
Top-placing teams at the 2018 National Ocean Sciences Bowl:
Montgomery Blair High School
Santa Monica High School
Marshfield High School
Albany High School
Newport High School
Fort Collins High School
Princeton High School (New Jersey)
Mount Sinai High School
Top-placing teams at the 2017 National Ocean Sciences Bowl:
Santa Monica High School
Marshfield High School
North Carolina School of Science and Math
Centerville High School
Bishop Sullivan Catholic High School
Eastside High School
Liberty Common High School
Oxford High School
Kalani High School won the sportsmanship award.
Top-placing teams at the 2016 National Ocean Sciences Bowl:
Albany High School
Marshfield High School
Santa Monica High School
Liberty Common High School
Boise High School
Lexington High School
E. O. Smith High School
Montgomery Blair High School
York High School won the sportsmanship award.
Top-placing teams at the 2015 National Ocean Sciences Bowl:
Boise High School
Dexter High School
Marshfield High School
Mission San Jose High School
Mount Sinai High School
Lexington High School
Chaparral Star Academy
Arcadia High School
Sanger High School won the sportsmanship award.
Top-placing teams at the 2014 National Ocean Sciences Bowl:
Boise High School
Arcadia High School
Juneau-Douglas High School
Bishop Sullivan Catholic High School
Eastside High School
Chaparral Star Academy
Thomas Jefferson High School for Science and Technology
Lexington High School
Langham Creek High School won the sportsmanship award.
Top-placing teams at the 2013 National Ocean Sciences Bowl:
Arcadia High School
Lexington High School
Juneau-Douglas High School
Neah-Kah-Nie High School
Albany High School
Greenhills High School
Dana Hills High School
Maui High School
Annapolis Christian Academy won the sportsmanship award.
Top-placing teams at the 2012 National Ocean Sciences Bowl:
Marshfield High School
Raleigh Charter High School
Eastside High School
Lexington High School
Santa Monica High School
Maui High School
Albany High School
Loveland High School
Top-placing teams at the 2011 National Ocean Sciences Bowl:
Marshfield High School
Lexington High School
Santa Monica High School
Mt. Sinai High School
Contoocook Valley Regional High School
Mission San Jose High School
State College High School
North Carolina School of Science and Mathematics
Top-placing teams at the 2010 National Ocean Sciences Bowl:
Marshfield High School
Marine Academy of Science and Technology
Mission San Jose High School
La Jolla High School
Punahou School
Neah-Kah-Nie High School
Thomas Jefferson High School for Science and Technology
Arcadia High School
Mount Sinai High School
Langham Creek High School won the sportsmanship award.
Top-placing teams at the 2009 National Ocean Sciences Bowl:
Marshfield High School
Lexington High School
Cranston High School West
Mission San Jose High School
Raleigh Charter High School
Top-placing teams at the 2008 National Ocean Sciences Bowl:
Lincoln-Sudbury Regional High School
Mission San Jose High School
Santa Monica High School
Dexter High School
La Jolla High School
Kealakehe High School won the sportsmanship award.
Top-placing teams at the 2007 National Ocean Sciences Bowl:
Contoocook Valley Regional High School (Peterborough, New Hampshire)
Cranston High School West (Cranston, Rhode Island)
Lincoln-Sudbury Regional High School (Sudbury, Massachusetts)
Santa Monica High School (Santa Monica, CA)
Smoky Hill High School (Aurora, CO)
Churchville-Chili High School (Churchville, New York)
Dexter High School (Dexter, MI)
Durant High School (Plant City, FL)
Poplarville High School won the sportsmanship award.
Top-placing teams at the 2006 National Ocean Sciences Bowl:
Lincoln-Sudbury Regional High School (Sudbury, Massachusetts)
Poudre High School (Fort Collins, CO)
Santa Monica High School (Santa Monica, CA)
Albany High School (Albany, CA)
MAST Academy (Miami, FL)
Oconee County High School (Oconee County, Georgia)
Langham Creek High School (Langham Creek, TX)
Thomas Jefferson High School for Science and Technology (Arlington, VA)
Top-placing teams at the 2005 National Ocean Sciences Bowl:
Cranston High School West (Cranston, Rhode Island)
Lincoln-Sudbury Regional High School (Sudbury, Massachusetts)
Mission San Jose High School (Fremont, California)
Oconee County High School (Oconee County, Georgia)
La Jolla High School (La Jolla, California)
Maui High School (Maui County, Hawaii)
Santa Monica High School (Santa Monica, California)
Incarnate Word Academy (Corpus Christi, Texas)
Past National Ocean Sciences Bowl Winners:
2004 - Mission San Jose High School (Fremont, California)
2003 - Cranston High School West (Cranston, Rhode Island)
2002 - Lexington High School, (Lexington, MA)
2001 - Lexington High School, (Lexington, MA)
2000 - Lexington High School, (Lexington, MA)
1999 - Lexington High School, (Lexington, MA)
1998 - Lexington High School, (Lexington, MA)
Prizes
The prizes for placing at the national competition vary from year to year. In recent years, the top two teams have received week-long experiential trips while many of the other teams at the national competition have received smaller prizes.
2016
1st: Monaco (Courtesy of Prince Albert II of Monaco Foundation)
2nd: University of Milwaukee, Wisconsin, School of Freshwater Sciences
2015
1st: NOAA Auke Bay Laboratory, Juneau, Alaska, and Sitka Sound Science Center, Sitka, Alaska
2nd: University of Texas Marine Science Institute, Port Aransas, Texas, and Harte Research Institute for Gulf of Mexico Studies, Corpus Christi, Texas
2014
1st: Shoals Marine Lab, Portsmouth, New Hampshire, University of Maine Darling Marine Center, Walpole, Maine, Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, and Gulf of Maine Research Institute, Portland, Maine
2nd: Smithsonian, Washington DC, NOAA Oxford Laboratory, Oxford, Maryland, Khaled bin Sultan Living Oceans Foundation, Annapolis, Maryland
2013
1st: University of Massachusetts Dartmouth, North Dartmouth, Massachusetts, Hoods Hole Oceanographic Institute, Falmouth, Massachusetts, University of Rhode Island, South Kingston, Rhode Island, and Connecticut Sea Grant, Groton, Connecticut
2nd: University of Georgia Marine Extension Service, Savannah, Georgia, Skidaway Institute of Oceanography, Savannah, Georgia, and Savannah State University, Savannah, Georgia
See also
Science Bowl
External links
Official NOSB website
Center for Ocean Leadership
References
Science competitions
Student quiz competitions
Science events in the United States | National Ocean Sciences Bowl | [
"Technology"
] | 3,342 | [
"Science and technology awards",
"Science competitions"
] |
1,629,621 | https://en.wikipedia.org/wiki/Pull-up%20resistor | In electronic logic circuits, a pull-up resistor (PU) or pull-down resistor (PD) is a resistor used to ensure a known state for a signal. It is typically used in combination with components such as switches and transistors, which physically interrupt the connection of subsequent components to ground or to VCC. Without such resistor, closing the switch creates a direct connection to ground or VCC; when the switch is open, the rest of the circuit would be left floating (i.e. it would have an indeterminate voltage), which is generally undesirable.
For a switch that is used to connect a circuit to ground, a pull-up resistor (connected between the circuit and VCC) ensures a well-defined voltage (i.e. VCC, or logical high) when the switch is open. For a switch that is used to connect a circuit to VCC (e.g. if the switch or button is used to transmit a "high" signal), a pull-down resistor connected between the circuit and ground ensures a well-defined ground voltage (i.e. logical low) across the remainder of the circuit when the switch is open.
Principle
An open switch is not equivalent to a component with infinite impedance. The stationary voltage in any loop with an open switch cannot be determined by Kirchhoff's laws, while that with a component with infinite impedance can be determined by such laws. Consequently, the voltages across those critical components (such as the logic gate in the example on the right), which are only in loops involving the open switch, are undefined, too. A pull-up resistor effectively establishes an additional loop over the critical components, ensuring that the voltage is well-defined even when the switch is open.
Optimal resistance
For a pull-up resistor to serve only this one purpose and not interfere with the circuit otherwise, a resistor with an appropriate amount of resistance must be used. For this, it is assumed that the critical components have infinite or sufficiently high impedance, which is guaranteed, for example, for logic gates made from FETs. In this case, when the switch is open, the voltage drop across a pull-up resistor (with sufficiently low impedance) practically vanishes, and the circuit looks like a wire directly connected to VCC. On the other hand, when the switch is closed, the pull-up resistor must have sufficiently high impedance in comparison to the closed switch to not affect the connection to ground. Together, these two conditions can be used to derive an appropriate value for the impedance of the pull-up resistor. However, usually, only a lower bound is derived, assuming that the critical components do indeed have infinite impedance.
A resistor with relatively low resistance (relative to the circuit it is in) is often called a "strong" pull-up or pull-down; when the circuit is open, it will pull the output high or low very quickly (just as the voltage changes in an RC circuit), but will draw more current. A resistor with relatively high resistance is called a "weak" pull-up or pull-down; when the circuit is open, it will pull the output high or low more slowly, but will draw less current. This current, which is essentially wasted energy, only flows when the switch is closed, and technically for a brief period after it is opened until the charge built up in the circuit has been discharged to ground.
Applications
A pull-up resistor may be used when interfacing logic gates to inputs. For example, an input signal may be pulled by a resistor, then a switch or jumper strap can be used to connect that input to ground. This can be used for configuration information, to select options or for troubleshooting of a device.
Pull-up resistors may be used at logic outputs where the logic device cannot source current such as open-collector TTL logic devices. Such outputs are used for driving external devices, for a wired-OR function in combinational logic, or for a simple way of driving a logic bus with multiple devices connected to it.
Pull-up resistors may be discrete devices mounted on the same circuit board as the logic devices. Many microcontrollers intended for embedded control applications have internal, programmable pull-up resistors for logic inputs so that not many external components are needed.
Pull-down resistors can be safely used with CMOS logic gates because the inputs are voltage-controlled. TTL logic inputs that are left unconnected inherently float high, and require a much lower valued pull-down resistor to force the input low. A standard TTL input at logic "1" is normally operated assuming a source current of 40 μA, and a voltage level above 2.4 V, allowing a pull-up resistor of no more than 50 kohms; whereas the TTL input at logic "0" will be expected to sink 1.6 mA at a voltage below 0.8 V, requiring a pull-down resistor less than 500 ohms. Holding unused TTL inputs low consumes more current. For that reason, pull-up resistors are preferred in TTL circuits.
In bipolar logic families operating at 5 VDC, a typical pull-up resistor value will be 1000–5000 Ω, based on the requirement to provide the required logic level current over the full operating range of temperature and supply voltage. For CMOS and MOS logic, much higher values of resistor can be used, several thousand to a million ohms, since the required leakage current at a logic input is small.
Drawbacks
Some disadvantages of pull-up resistors are the extra power consumed when current is drawn through the resistor and the reduced speed of a pull-up compared to an active current source. Certain logic families are susceptible to power supply transients introduced into logic inputs through pull-up resistors, which may force the use of a separate filtered power source for the pull-ups.
See also
Rp (USB) - a specific type of pull-up resistor in USB-C connectors
Rd (USB), Ra (USB) - specific types of pull-down resistors in USB-C connectors
Three-state logic
References
Paul Horowitz and Winfield Hill, The Art of Electronics, 2nd edition, Cambridge University Press, Cambridge, England, 1989,
Electronic circuits
Resistive components
de:Open circuit#Pull-up | Pull-up resistor | [
"Physics",
"Engineering"
] | 1,331 | [
"Physical quantities",
"Electronic circuits",
"Resistive components",
"Electronic engineering",
"Electrical resistance and conductance"
] |
1,629,687 | https://en.wikipedia.org/wiki/Carry%20%28arithmetic%29 | In elementary arithmetic, a carry is a digit that is transferred from one column of digits to another column of more significant digits. It is part of the standard algorithm to add numbers together by starting with the rightmost digits and working to the left. For example, when 6 and 7 are added to make 13, the "3" is written to the same column and the "1" is carried to the left. When used in subtraction the operation is called a borrow.
Carrying is emphasized in traditional mathematics, while curricula based on reform mathematics do not emphasize any specific method to find a correct answer.
Carrying makes a few appearances in higher mathematics as well. In computing, carrying is an important function of adder circuits.
Manual arithmetic
A typical example of carry is in the following pencil-and-paper addition:
1
27
+ 59
----
86
7 + 9 = 16, and the digit 1 is the carry.
The opposite is a borrow, as in
−1
47
− 19
----
28
Here, , so try , and the 10 is got by taking ("borrowing") 1 from the next digit to the left. There are two ways in which this is commonly taught:
The ten is moved from the next digit left, leaving in this example in the tens column. According to this method, the term "borrow" is a misnomer, since the ten is never paid back.
The ten is copied from the next digit left, and then 'paid back' by adding it to the subtrahend in the column from which it was 'borrowed', giving in this example in the tens column.
Mathematics education
Traditionally, carry is taught in the addition of multi-digit numbers in the 2nd or late first year of elementary school. However, since the late 20th century, many widely adopted curricula developed in the United States such as TERC omitted instruction of the traditional carry method in favor of invented arithmetic methods, and methods using coloring, manipulatives, and charts. Such omissions were criticized by such groups as Mathematically Correct, and some states and districts have since abandoned this experiment, though it remains widely used.
Higher mathematics
Kummer's theorem states that the number of carries involved in adding two numbers in base is equal to the exponent of the highest power of dividing a certain binomial coefficient.
When several random numbers of many digits are added, the statistics of the carry digits bears an unexpected connection with Eulerian numbers and the statistics of riffle shuffle permutations.
In abstract algebra, the carry operation for two-digit numbers can be formalized using the language of group cohomology. This viewpoint can be applied to alternative characterizations of the real numbers.
Mechanical calculators
Carry represents one of the basic challenges facing designers and builders of mechanical calculators. They face two basic difficulties: The first one stems from the fact that a carry can require several digits to change: in order to add 1 to 999, the machine has to increment 4 different digits. Another challenge is the fact that the carry can "develop" before the next digit finished the addition operation.
Most mechanical calculators implement carry by executing a separate carry cycle after the addition itself. During the addition, each carry is "signaled" rather than performed, and during the carry cycle, the machine increments the digits above the "triggered" digits. This operation has to be performed sequentially, starting with the ones digit, then the tens, the hundreds, and so on, since adding the carry can generate a new carry in the next digit.
Some machines, notably Pascal's calculator, the second known calculator to be built, and the oldest surviving, use a different method: incrementing the digit from 0 to 9, cocks a mechanical device to store energy, and the next increment, which moves the digit from 9 to 0, releases this energy to increment the next digit by 1. Pascal used weights and gravity in his machine. Another notable machine using similar method is the highly successful 19th century Comptometer, which replaced the weights with springs.
Some innovative machines use continuous transmission: adding 1 to any digit, advances the next one by 1/10 (which in turn advances the next one by 1/100 and so on). Some innovative early calculators, notably Chebyshev calculator from 1870, and a design by Selling, from 1886, used this method, but neither were successful. In the early 1930, Marchant calculator implemented continuous transmission with great success, starting with the aptly named "Silent Speed" calculator. Marchant (later to become SCM Corporation) continued to use and improve it, and made continuous-transmission calculators with unmatched speed, into the late 1960s, to the end of the mechanical calculator era.
Computing
When speaking of a digital circuit like an adder, the word carry is used in a similar sense.
In most computers, the carry from the most significant bit of an arithmetic operation (or bit shifted out from a shift operation) is placed in a special carry bit which can be used as a carry-in for multiple precision arithmetic or tested and used to control execution of a computer program. The same carry bit is also generally used to indicate borrows in subtraction, though the bit's meaning is inverted due to the effects of two's complement arithmetic. Normally, a carry bit value of "1" signifies that an addition overflowed the ALU, and must be accounted for when adding data words of lengths greater than that of the CPU. For subtractive operations, two (opposite) conventions are employed as most machines set the carry flag on borrow while some machines (such as the 6502 and the PIC) instead reset the carry flag on borrow (and vice versa).
A carry can lead to integer overflow.
References
External links
Carrying - nLab
Elementary arithmetic
Computer arithmetic
fr:Retenue
ja:ステータスレジスタ#キャリー | Carry (arithmetic) | [
"Mathematics"
] | 1,236 | [
"Elementary mathematics",
"Computer arithmetic",
"Arithmetic",
"Elementary arithmetic"
] |
1,629,772 | https://en.wikipedia.org/wiki/Medical%20Waste%20Tracking%20Act | The Medical Waste Tracking Act of 1988 was a United States federal law concerning the illegal dumping of body tissues, blood wastes and other contaminated biological materials. It established heavy penalties for knowingly endangering life through noncompliance. The law expired in 1991.
Authority
The law created a two-year program that went into effect in New York, New Jersey, Connecticut, Rhode Island and Puerto Rico on June 24, 1989, and expired on June 21, 1991.
The H.R. 3515 legislation was passed by the 100th Congressional session and signed into law by the 40th President of the United States Ronald Reagan on November 2, 1988.
History
Beginning on August 13, 1987, a "30-mile garbage slick" composed primarily of medical and household wastes prompted extensive closures of numerous New Jersey and New York beaches. Investigations ongoing throughout the year indicated that the waste likely originated from "New York City's marine transfer stations … and the Southwest Brooklyn Incinerator and Transfer Station in particular…" The then-assistant commissioner of the New Jersey Department of Environmental Protection stated his belief that the cause of pollution was intentional rather than accidental; "sealed plastic garbage bags, he said, were cut at the top, so their contents could disperse through the ocean." Such a deliberate action may have arisen given the high cost (~$1500/ton) associated with the legal disposal of the waste, thus incentivizing private waste contractors to dump illegally to avoid high fees.
Ultimately the Medical Waste Tracking Act of 1988 (MWTA) arose from the aftermath of this situation. It was designed primarily to monitor the treatment of medical wastes through their creation, transportation and destruction, i.e. from "cradle-to-grave." Congress approved the bill "to amend the Solid Waste Disposal Act to require the Administrator of the Environmental Protection Agency (EPA) to promulgate regulations on the management of infections waste." In short, Congress enacted the MWTA as a pilot study to better determine how the life cycle of medical wastes played out under federal regulations.
Purpose
Definitions
Section 11002 of the MWTA, "Listing of Medical Wastes," provides a listing of definitions on what materials will be classified as "medical wastes" under the act. The list includes within its definitions: "cultures and stocks of infectious agents," "pathological wastes" such as body tissues, blood wastes and blood byproducts, sharps, contaminated carcasses and beddings of animals, surgery or autopsy wastes that were once in contact with infectious agents, "laboratory wastes," "dialysis wastes that were in contact with the blood of patients undergoing hemodialysis," medical equipment having come in contact with infectious agents, and further contaminated biological materials. Defining what objects were to be classified as medical wastes was crucial to ensure that all municipalities under the MWTA would be monitoring similar materials.
Management and tracking
Section 11003, "Tracking of Medical Waste," outlined how the program should manage the transportation of waste materials. Four requirements were primarily identified; first, to provide a means of monitoring "the transportation of waste from the generator to the disposal facility" unless said waste had previously been incinerated. Secondly, to be able to ensure the "generator of the waste" that the waste had been "received by the disposal facility." Next to develop a uniform form for the tracking of materials across states and finally to develop a means to label and contain the wastes for the safety of the handlers.
Following this, Section 11004 on "Inspections" provides provisions allowing for agents of the EPA to "enter… any establishment… where medical wastes are or have been generated" so as to conduct "monitoring", "testing", or to "obtain samples from any person.". This process would allow for the Agency to legally enter generating facilities for the purpose of determining if infectious agents and materials were being handled as prescribed by the EPA Administrator.
Enforcement
A major point of importance within the MWTA involves its inclusion of enforcement laws within the legislation. This becomes notable as it allows for one of the first instances in which an agency of the federal government may prosecute those charged with violation of regulations dealing with medical wastes. Following enactment of the MWTA the EPA Administrator may be allowed to "commence civil action in the United States district court in the district in which the violation occurred" against those being charged with the violation.
Penalties ranged based on the level of violation, whether it was done with intention, and if such acts endangered the lives of other individuals. Minor violations of compliance orders would have resulted in a fine of $25,000 per day of "continued noncompliance." Criminal penalties against those knowingly and intentionally violating the regulations of the MWTA may face two years of imprisonment or a $50,000 fine while those guilty of knowingly endangering the life of another through noncompliance may face upwards of fifteen years imprisonment and a $1,000,000 fine.
Outcomes
Through the information gathered during the promulgation of regulations for the MWTA, over a period of ten years the EPA eventually "concluded that the disease-causing potential of medical waste is greatest at the point of generation and naturally tapers off after that point... Thus, risk to the general public of disease caused by exposure to medical waste is likely to be much lower than risk for the occupationally exposed individual."
After expiration of the MWTA, state environmental and health agencies have continued to regulate medical waste, rather than EPA. Other federal agencies have issued safety regulations governing the handling of medical waste, including the Centers for Disease Control and Prevention, Occupational Safety and Health Administration, and the Food and Drug Administration.
See also
Resource Conservation and Recovery Act - current U.S. federal law regulating medical waste
Syringe Tide (in 1987 and 1988)
References
1988 in American law
100th United States Congress
United States federal environmental legislation
Waste legislation in the United States
Pollution in the United States
United States Environmental Protection Agency
1988 in the environment
Medical regulation in the United States
Medical waste
Presidency of Ronald Reagan | Medical Waste Tracking Act | [
"Biology"
] | 1,240 | [
"Medical waste"
] |
8,952,201 | https://en.wikipedia.org/wiki/Selexol | Selexol is the trade name for an acid gas removal solvent that can separate acid gases such as hydrogen sulfide and carbon dioxide from feed gas streams such as synthesis gas produced by gasification of coal, coke, or heavy hydrocarbon oils. By doing so, the feed gas is made more suitable (less sour) for combustion and/or further processing. It is made up of dimethyl ethers of polyethylene glycol.
Process description
In the Selexol process (now licensed by UOP LLC), the Selexol solvent dissolves (absorbs) the acid gases from the feed gas at relatively high pressure, usually 300 to 2000 psia (2.07 to 13.8 MPa). The rich solvent containing the acid gases is then let down in pressure and/or steam stripped to release and recover the acid gases. The Selexol process can operate selectively to recover hydrogen sulfide and carbon dioxide as separate streams, so that the hydrogen sulfide can be sent to either a Claus unit for conversion to elemental sulfur or to a wet sulfuric acid process unit for conversion to sulfuric acid while, at the same time, the carbon dioxide can be sequestered or used for enhanced oil recovery. The Selexol process is similar to the Rectisol process, which uses refrigerated methanol as the solvent. The Selexol solvent is a mixture of the dimethyl ethers of polyethylene glycol.
Selexol is a physical solvent, unlike amine based acid gas removal solvents that rely on a chemical reaction with the acid gases. Since no chemical reactions are involved, Selexol usually requires less energy than the amine based processes. However, at feed gas pressures below about 300 psia (2.07 MPa), the Selexol solvent capacity (in amount of acid gas absorbed per volume of solvent) is reduced and the amine based processes will usually be superior.
See also
Hydrodesulfurization
Rectisol
Amine treating
References
External links
Selexol Process
Chemical processes
Acid gas control
Natural gas
Oil refining | Selexol | [
"Chemistry"
] | 443 | [
"Petroleum technology",
"Chemical processes",
"Oil refining",
"nan",
"Chemical process engineering"
] |
8,952,532 | https://en.wikipedia.org/wiki/Anautogeny | In entomology, anautogeny is a reproductive strategy in which an adult female insect must eat a particular sort of meal (generally vertebrate blood) before laying eggs in order for her eggs to mature. This behavior is most common among dipteran insects, such as mosquitoes. Anautogenous animals often serve as vectors for infectious disease in their hosts because of their contact with hosts' blood. The opposite trait (needing no special food as an adult to successfully reproduce) is known as autogeny.
Factors governing anautogeny
Anautogenous insects generally reach adulthood without sufficient reserves of nutrients (particularly protein) to produce viable eggs, necessitating additional feeding as adults. A high-protein meal, usually of blood, allows the production of yolk to nourish the eggs and makes reproduction possible. This blood is typically obtained through ectoparasitism on large vertebrates.
However, even individuals who do have the reserves needed to produce viable eggs may still be unable to reproduce without a blood meal, because egg maturation in many anautogenous species depends upon hormones that are released when blood is consumed. Further, females with certain genotypes are anautogenous by default but can be triggered to reproduce autogenously by mating with a male, possibly because of hormones released or acquired during mating or possibly because of some nutritional supplement the mating provides.
Individuals of the same species can be found to exhibit autogeny or anautogeny depending on their genotypes as well as on environmental circumstances and the type and amount of nourishment they obtained in their larval stage. Mathematical models have indicated that anautogeny can be an advantageous strategy for insect reproduction under favorable conditions (particularly when hosts are easy to find, when the insects have a good chance of surviving the blood-feeding, and when anautogeny contributes to increased fecundity).
Anatomy and physiology
Anautogeny and consequent blood-feeding is seen mainly among the dipteran insects, including mosquitoes, black flies, sand flies, horse flies, and biting midges. Most anautogenous dipterans possess sharp, blade-like mandibles for extracting blood, though these mouthparts are often underdeveloped in the male. Since these species get additional nourishment from other fluid foods such as nectar or fruit juices, they exhibit a "dual sense of hunger" by which they regulate their intake of sugary foods and proteinaceous foods separately.
In insects (as in other non-mammalian animals), egg maturation begins with vitellogenesis, the deposition of yolk proteins triggered by the release of juvenile hormones. In anautogenous mosquitoes, yolk production genes are strongly activated after a blood meal through a process involving the target of rapamycin signal pathway. In particular, certain amino acids found in the blood proteins seem to be necessary for the activation of the vitellogenin gene.
Autogeny
The need to feed on blood before laying eggs is less remarkable in animals whose ordinary diets consist largely or entirely of blood, such as ticks; in these taxa it is autogeny, or the ability to lay eggs without a blood meal, that is more remarked upon. Many insects are able to produce eggs without ingesting proteinaceous food as adults, relying upon stores of nutrients they acquired as larvae. Most, however, can lay relatively few eggs without feeding on protein, and almost all require a high-protein meal to lay additional eggs after a first clutch.
See also
Hematophagy
Mosquito-borne disease
Parasitism
References
Haematophagy
Insect physiology
Parasitism | Anautogeny | [
"Biology"
] | 742 | [
"Parasitism",
"Symbiosis"
] |
8,952,773 | https://en.wikipedia.org/wiki/Traveling%20screen | A traveling screen is a type of water filtration device that has a continuously moving mesh screen that is used to catch and remove debris. This type of device is usually found in water intake systems for drinking water and sewage treatment plants. Screening is considered the first step in conventional sewage treatment processes. Screening is also used in cooling water intakes in steam electric power plants, hydroelectric generators, petroleum refineries, and chemical plants. Traveling screens are used to divert fish, shellfish and other aquatic species, and debris including leaves, sticks, and trash; for the purpose of preventing damage to a facility's treatment or cooling system.
See also
Bar screen
Fish screen
References
Water filters
Water treatment | Traveling screen | [
"Chemistry",
"Engineering",
"Environmental_science"
] | 140 | [
"Water filters",
"Water treatment",
"Filters",
"Water pollution",
"Civil engineering",
"Civil engineering stubs",
"Environmental engineering",
"Water technology"
] |
8,952,788 | https://en.wikipedia.org/wiki/Mycovirus | Mycoviruses (Ancient Greek: μύκης ("fungus") + Latin ), also known as mycophages, are viruses that infect fungi. The majority of mycoviruses have double-stranded RNA (dsRNA) genomes and isometric particles, but approximately 30% have positive-sense, single-stranded RNA (+ssRNA) genomes.
True mycoviruses demonstrate an ability to be transmitted to infect other healthy fungi. Many double-stranded RNA elements that have been described in fungi do not fit this description, and in these cases they are referred to as virus-like particles or VLPs. Preliminary results indicate that most mycoviruses co-diverge with their hosts, i.e. their phylogeny is largely congruent with that of their primary hosts. However, many virus families containing mycoviruses have only sparsely been sampled. Mycovirology is the study of mycoviruses. It is a special subdivision of virology and seeks to understand and describe the taxonomy, host range, origin and evolution, transmission and movement of mycoviruses and their impact on host phenotype.
History
The first record of an economic impact of mycoviruses on fungi was recorded in cultivated mushrooms (Agaricus bisporus) in the late 1940s and was called the La France disease. Hollings found more than three different types of viruses in the abnormal sporophores. This report essentially marks the beginning of mycovirology.
The La France Disease is also known as X disease, watery stripe, dieback and brown disease. Symptoms include:
Reduced yield
Slow and aberrant mycelial growth
Waterlogging of tissue
Malformation
Premature maturation
Increased post-harvest deterioration (reduced shelf life)
Mushrooms have shown no resistance to the virus, and so control has been limited to hygienic practises to stop the spread of the virus.
Perhaps the best known mycovirus is Cryphonectria parasitica hypovirus 1 (CHV1). CHV1 is exceptional within mycoviral research for its success as a biocontrol agent against the fungus C. parasitica, the causative agent of chestnut blight, in Europe, but also because it is a model organism for studying hypovirulence in fungi. However, this system is only being used in Europe routinely because of the relatively small number of vegetative compatibility groups (VCGs) on the continent. By contrast, in North America the distribution of the hypovirulent phenotype is often prevented because an incompatibility reaction prevents fungal hyphae from fusing and exchanging their cytoplasmic content. In the United States, at least 35 VCGs were found. A similar situation seems to be present in China and Japan, where 71 VCGs have been identified so far.
Taxonomy
The majority of mycoviruses have double-stranded RNA (dsRNA) genomes and isometric particles, but approximately 30% have positive-sense, single-stranded RNA (+ssRNA) genomes. However, negative single-stranded RNA viruses and single-stranded DNA viruses have also been described. The updated 9th ICTV report on virus taxonomy lists over 90 mycovirus species covering 10 viral families, of which 20% were not assigned to a genus or, in some cases, not even to a family.
Isometric forms predominate mycoviral morphologies in comparison to rigid rods, flexuous rods, club-shaped particles, enveloped bacilliform particles, and Herpesvirus-like viruses. The lack of genomic data often hampers a conclusive assignment to already established groups of viruses or makes it impossible to erect new families and genera. The latter is true for many unencapsidated dsRNA viruses, which are assumed to be viral, but missing sequence data has prevented their classification so far. So far, viruses of the families Partitiviridae, Totiviridae, and Narnaviridae are dominating the "mycovirus sphere".
Host range and incidence
Mycoviruses are common in fungi (Herrero et al., 2009) and are found in all four phyla of the true fungi: Chytridiomycota, Zygomycota, Ascomycota and Basidiomycota. Fungi are frequently infected with two or more unrelated viruses and also with defective dsRNA and/or satellite dsRNA. There are also viruses that simply use fungi as vectors and are distinct from mycoviruses because they cannot reproduce in the fungal cytoplasm.
It is generally assumed that the natural host range of mycoviruses is confined to closely related vegetability compatibility groups or VCGs which allow for cytoplasmic fusion, but some mycoviruses can replicate in taxonomically different fungal hosts. Good examples are mitoviruses found in the two fungal species S. homoeocarpa and Ophiostoma novo-ulmi. Nuss et al. (2005) described that it is possible to extend the natural host range of C. parasitica hypovirus 1 (CHV1) to several fungal species that are closely related to C. parasitica using in vitro virus transfection techniques. CHV1 can also propagate in the genera Endothia and Valsa, which belong to the two distinct families Cryphonectriaceae and Diaporthaceae, respectively. Furthermore, some human pathogenic fungi are also found to be naturally infected with mycoviruses, including AfuPmV-1 of Aspergillus fumigatus and TmPV1 of Talaromyces marneffei (formerly Penicillium marneffei).
In one study, forty patients with acute lymphoblastic leukemia were found to have antibodies to a mycovirus-containing Aspergillus flavus.In another research report, exposure of mononuclear cells from patients with acute lymphoblastic leukemia in full remission resulted in the re-development of the genetic and cell surface phenotypes characteristic of acute lymphoblastic leukemia.
Origin and evolution
Viruses consisting of dsRNA as well as ssRNA are assumed to be very ancient and presumably originated from the "RNA world" as both types of RNA viruses infect bacteria as well as eukaryotes. Although the origin of viruses is still not well understood, recently presented data suggest that viruses may have invaded the emerging "supergroups" of eukaryotes from an ancestral pool during a very early stage of life on earth. According to Koonin, RNA viruses colonized eukaryotes first and subsequently co-evolved with their hosts. This concept fits well with the proposed "ancient co-evolution hypothesis", which also assumes a long co-evolution of viruses and fungi. The "ancient co-evolution hypothesis" could explain why mycoviruses are so diverse.
It has also been suggested that it is very likely that plant viruses containing a movement protein evolved from mycoviruses by introducing an extracellular phase into their life cycle rather than eliminating it. Furthermore, the recent discovery of an ssDNA mycovirus has tempted some researchers to suggest that RNA and DNA viruses might have common evolutionary mechanisms. However, there are many cases where mycoviruses are grouped together with plant viruses. For example, CHV1 showed phylogenetic relatedness to the ssRNA genus Potyvirus, and some ssRNA viruses, which were assumed to confer hypovirulence or debilitation, were often found to be more closely related to plant viruses than to other mycoviruses. Therefore, another theory arose that these viruses moved from a plant host to a plant pathogenic fungal host or vice versa. This "plant virus hypothesis" may not explain how mycoviruses developed originally, but it could help to understand how they evolved further.
Transmission
A significant difference between the genomes of mycoviruses to other viruses is the absence of genes for ‘cell-to-cell movement’ proteins. It is therefore assumed that mycoviruses only move intercellularly during cell division (e.g. sporogenesis) or via hyphal fusion. Mycoviruses might simply not need an external route of infection as they have many means of transmission and spread due to their fungal host's life style:
Plasmogamy and cytoplasmic exchange over extended periods of time
Production of vast amounts of asexual spores
Overwintering via sclerotia
More or less effective transmission into sexual spores
However, there are potential barriers to mycovirus spread due to vegetative incompatibility and variable transmission to sexual spores. Transmission to sexually produced spores can range from 0% to 100% depending on the virus-host combination. Transmission between species of the same genus sharing the same habitat has also been reported including Cryphonectria (C. parasitica and C. sp), Sclerotinia (Sclerotinia sclerotiorum and S. minor), and Ophiostoma (O. ulmi and O. novo-ulmi). Intraspecies transmission has also been reported between Fusarium poae and black Aspergillus isolates. However, it is not known how fungi overcome the genetic barrier; whether there is some form of recognition process during physical contact or some other means of exchange, such as vectors. Research using Aspergillus species indicated that transmission efficiencies might depend on the hosts viral infection status (infected with no, different, or same virus), and that mycoviruses might play a role in the regulation of secondary mycoviral infection. Whether this is also true for other fungi is not yet known. In contrast to acquiring mycoviruses spontaneously, the loss of mycoviruses seems very infrequent and suggests that either viruses actively moved into spores and new hyphal tips, or the fungus might facilitate the mycoviral transport in some other way.
Movement of mycoviruses within fungi
Although it is not known yet whether viral transport is an active or passive process, it is generally assumed that fungal viruses move forward by plasma streaming. Theoretically they could drift with the cytoplasm as it extends into new hyphae, or attach to the web of microtubuli, which would drag them through the internal cytoplasmic space. That might explain how they pass through septa and bypass woronin bodies. However, some researchers have found them located next to septum walls, which could imply that they ‘got stuck’ and were not able to move actively forward themselves. Others have suggested that the transmission of viral mitochondrial dsRNA may play an important role in the movement of mitoviruses found in Botrytis cinerea.
Impact on host phenotype
Phenotypic effects of mycoviral infections can vary from advantageous to deleterious, but most of them are asymptomatic or cryptic. The connection between phenotype and mycovirus presence is not always straightforward. Several reasons may account for this. First, the lack of appropriate infectivity assays often hindered the researcher from reaching a coherent conclusion. Secondly, mixed infection or unknown numbers of infecting viruses make it very difficult to associate a particular phenotypic change with the investigated virus.
Although most mycoviruses often do not seem to disturb their host's fitness, this does not necessarily mean they are living unrecognized by their hosts. A neutral co-existence might just be the result of a long co-evolutionary process. Accordingly, symptoms may only appear when certain conditions of the virus-fungus-system change and get out of balance. This could be external (environmental) as well as internal (cytoplasmic). It is not known yet why some mycoviruses-fungus-combinations are typically detrimental while others are asymptomatic or even beneficial. Nevertheless, harmful effects of mycoviruses are economically interesting, especially if the fungal host is a phytopathogen and the mycovirus could be exploited as biocontrol agent. The best example is represented by the case of CHV1 and C. parasitica. Other examples of deleterious effects of mycoviruses are the ‘La France’ disease of A. bisporus and the mushroom diseases caused by Oyster mushroom spherical virus and Oyster mushroom isometric virus.
In summary, the main negative effects of mycoviruses are:
Decreased growth rate
Lack of sporulation
Change of virulence
Reduced germination of spores
Hypovirulent phenotypes do not appear to correlate with specific genome features and it seems there is not one particular metabolic pathway causing hypovirulence but several. In addition to negative effects, beneficial interactions do also occur. Well described examples are the killer phenotypes in yeasts and Ustilago. Killer isolates secrete proteins that are toxic to sensitive cells of the same or closely related species while the producing cells themselves are immune. Most of these toxins degrade the cell membrane. There are potentially interesting applications of killer isolates in medicine, food industry, and agriculture. A three-part system involving a mycovirus of an endophytic fungus (Curvularia protuberata) of the grass Dichanthelium lanuginosum has been described, which provides a thermal tolerance to the plant, enabling it to inhabit adverse environmental niches. In medically important fungi, an uncharacterized A78 virus of A. fumigatus causes mild hypervirulent effect on pathogenicity when tested on Galleria mellonella (Greater wax moth). Furthermore, TmPV1, a dsRNA partitivirus, of Talaromyces marneffei (formerly Penicillium marneffei) was found to cause hypervirulence phenotype on T. marneffei when tested on a mouse model. These could imply mycoviruses may play important roles in the pathogensis of human pathogenic fungi.
Classification
Most fungal viruses belong to double-stranded RNA viruses, but about 30% belong to positive-strand RNA virus.
However, negative single-stranded RNA viruses and single-stranded DNA viruses have also been described. The ninth edition of the report of the International Committee on Taxonomy of Viruses lists more than 90 fungal viruses belonging to 10 families, of which about 20% of the viruses have not been incertae sedis due to insufficient sequence data and have not yet been determined. The shape of most fungal viruses is isometric.
References
Tebbi CK, Badiga A, Sahakian E, Arora AI, Nair S, Powers JJ, Achille AN, Jaglal MV, Patel S, Migone F. Plasma of Acute Lymphoblastic Leukemia Patients React to the Culture of a Mycovirus Containing Aspergillus flavus. J Pediatr Hematol Oncol. 2020 Jul;42(5):350-358. doi: 10.1097/MPH.0000000000001845. PMID 32576782.
Tebbi CK, Badiga A, Sahakian E, Powers JJ, Achille AN, Patel S, Migone F. Exposure to a mycovirus containing Aspergillus Flavus reproduces acute lymphoblastic leukemia cell surface and genetic markers in cells from patients in remission and not controls. Cancer Treat Res Commun. 2021;26:100279. doi: 10.1016/j.ctarc.2020.100279. Epub 2020 Dec 11. PMID 33348275.
Further reading
External links
Mycology | Mycovirus | [
"Biology"
] | 3,260 | [
"Mycology"
] |
8,953,468 | https://en.wikipedia.org/wiki/Equiareal%20map | In differential geometry, an equiareal map, sometimes called an authalic map, is a smooth map from one surface to another that preserves the areas of figures.
Properties
If M and N are two Riemannian (or pseudo-Riemannian) surfaces, then an equiareal map f from M to N can be characterized by any of the following equivalent conditions:
The surface area of f(U) is equal to the area of U for every open set U on M.
The pullback of the area element μN on N is equal to μM, the area element on M.
At each point p of M, and tangent vectors v and w to M at p,
where denotes the Euclidean wedge product of vectors and df denotes the pushforward along f.
Example
An example of an equiareal map, due to Archimedes of Syracuse, is the projection from the unit sphere to the unit cylinder outward from their common axis. An explicit formula is
for (x, y, z) a point on the unit sphere.
Linear transformations
Every Euclidean isometry of the Euclidean plane is equiareal, but the converse is not true. In fact, shear mapping and squeeze mapping are counterexamples to the converse.
Shear mapping takes a rectangle to a parallelogram of the same area. Written in matrix form, a shear mapping along the -axis is
Squeeze mapping lengthens and contracts the sides of a rectangle in a reciprocal manner so that the area is preserved. Written in matrix form, with λ > 1 the squeeze reads
A linear transformation multiplies areas by the absolute value of its determinant .
Gaussian elimination shows that every equiareal linear transformation (rotations included) can be obtained by composing at most two shears along the axes, a squeeze and (if the determinant is negative), a reflection.
In map projections
In the context of geographic maps, a map projection is called equal-area, equivalent, authalic, equiareal, or area-preserving, if areas are preserved up to a constant factor; embedding the target map, usually considered a subset of R2, in the obvious way in R3, the requirement above then is weakened to:
for some not depending on and .
For examples of such projections, see equal-area map projection.
See also
Jacobian matrix and determinant
References
Differential geometry
Functions and mappings | Equiareal map | [
"Mathematics"
] | 499 | [
"Mathematical analysis",
"Functions and mappings",
"Mathematical relations",
"Mathematical objects"
] |
8,953,588 | https://en.wikipedia.org/wiki/List%20of%20computer%20system%20manufacturers | A computer system is a nominally complete computer that includes the hardware, operating system (main software), and the means to use peripheral equipment needed and used for full or mostly full operation. Such systems may constitute personal computers (including desktop computers, portable computers, laptops, all-in-ones, and more), mainframe computers, minicomputers, servers, and workstations, among other classes of computing. The following is a list of notable manufacturers and sellers of computer systems, both present and past. There are currently companies in this incomplete list.
Current
Inactive
See also
Market share of personal computer vendors
List of computer hardware manufacturers
List of laptop brands and manufacturers
List of touch-solution manufacturers
Notes
References
Computing by company
Computing-related lists
Lists of manufacturers
Lists of information technology companies | List of computer system manufacturers | [
"Technology"
] | 160 | [
"Computer systems companies",
"Computing-related lists",
"Computer hardware companies",
"Computer systems",
"Computing by company",
"Computer industry",
"Computers"
] |
8,953,659 | https://en.wikipedia.org/wiki/Sodium%20pyruvate | Sodium pyruvate is a salt of the conjugate anion form of pyruvic acid, known as pyruvate. It is commonly added to cell culture media as an additional source of energy, but may also have protective effects against hydrogen peroxide. This was reported by Giandomenico et al. and has been confirmed by several independent groups.
Due to pyruvate being an intermediate in many pathways for metabolism including glycolysis, sodium pyruvate has been used in many experiments involving cell cultures to provide more energy. In adipocytes it was found that sodium pyruvate promoted increased uptake of insulin-mediated glucose. In the body, one way in which sodium pyruvate provides energy to cells is through pyruvate conversion to acetyl-CoA which then can enter the TCA cycle which produces energy and is linked to other energy producing processes.
Along with having antioxidant properties and energy producing effects, sodium pyruvate has the ability to cross the blood-brain barrier and is used in several studies on brain injury because of these characteristics.
References
Organic sodium salts | Sodium pyruvate | [
"Chemistry"
] | 236 | [
"Organic sodium salts",
"Salts"
] |
8,953,682 | https://en.wikipedia.org/wiki/Flatness%20%28systems%20theory%29 | Flatness in systems theory is a system property that extends the notion of controllability from linear systems to nonlinear dynamical systems. A system that has the flatness property is called a flat system. Flat systems have a (fictitious) flat output, which can be used to explicitly express all states and inputs in terms of the flat output and a finite number of its derivatives.
Definition
A nonlinear system
is flat, if there exists an output
that satisfies the following conditions:
The signals are representable as functions of the states and inputs and a finite number of derivatives with respect to time : .
The states and inputs are representable as functions of the outputs and of its derivatives with respect to time .
The components of are differentially independent, that is, they satisfy no differential equation of the form .
If these conditions are satisfied at least locally, then the (possibly fictitious) output is called flat output, and the system is flat.
Relation to controllability of linear systems
A linear system
with the same signal dimensions for as the nonlinear system is flat, if and only if it is controllable. For linear systems both properties are equivalent, hence exchangeable.
Significance
The flatness property is useful for both the analysis of and controller synthesis for nonlinear dynamical systems. It is particularly advantageous for solving trajectory planning problems and asymptotical setpoint following control.
Literature
M. Fliess, J. L. Lévine, P. Martin and P. Rouchon: Flatness and defect of non-linear systems: introductory theory and examples. International Journal of Control 61(6), pp. 1327-1361, 1995
A. Isidori, C.H. Moog et A. De Luca. A Sufficient Condition for Full Linearization via Dynamic State Feedback. 25th CDC IEEE, Athens, Greece, pp. 203 - 208, 1986
See also
Control theory
Control engineering
Controller (control theory)
Flat pseudospectral method
Control theory | Flatness (systems theory) | [
"Mathematics"
] | 396 | [
"Applied mathematics",
"Control theory",
"Dynamical systems"
] |
8,953,842 | https://en.wikipedia.org/wiki/Computational%20auditory%20scene%20analysis | Computational auditory scene analysis (CASA) is the study of auditory scene analysis by computational means. In essence, CASA systems are "machine listening" systems that aim to separate mixtures of sound sources in the same way that human listeners do. CASA differs from the field of blind signal separation in that it is (at least to some extent) based on the mechanisms of the human auditory system, and thus uses no more than two microphone recordings of an acoustic environment. It is related to the cocktail party problem.
Principles
Since CASA serves to model functionality parts of the auditory system, it is necessary to view parts of the biological auditory system in terms of known physical models. Consisting of three areas, the outer, middle and inner ear, the auditory periphery acts as a complex transducer that converts sound vibrations into action potentials in the auditory nerve. The outer ear consists of the external ear, ear canal and the ear drum. The outer ear, like an acoustic funnel, helps locating the sound source. The ear canal acts as a resonant tube (like an organ pipe) to amplify frequencies between 2–5.5 kHz with a maximum amplification of about 11 dB occurring around 4 kHz. As the organ of hearing, the cochlea consists of two membranes, Reissner’s and the basilar membrane. The basilar membrane moves to audio stimuli through the specific stimulus frequency matches the resonant frequency of a particular region of the basilar membrane. The movement the basilar membrane displaces the inner hair cells in one direction, which encodes a half-wave rectified signal of action potentials in the spiral ganglion cells. The axons of these cells make up the auditory nerve, encoding the rectified stimulus. The auditory nerve responses select certain frequencies, similar to the basilar membrane. For lower frequencies, the fibers exhibit "phase locking". Neurons in higher auditory pathway centers are tuned to specific stimuli features, such as periodicity, sound intensity, amplitude and frequency modulation.
There are also neuroanatomical associations of ASA through the posterior cortical areas, including the posterior superior temporal lobes and the posterior cingulate. Studies have found that impairments in ASA and segregation and grouping operations are affected in patients with Alzheimer's disease.
System Architecture
Cochleagram
As the first stage of CASA processing, the cochleagram creates a time-frequency representation of the input signal. By mimicking the components of the outer and middle ear, the signal is broken up into different frequencies that are naturally selected by the cochlea and hair cells. Because of the frequency selectivity of the basilar membrane, a filter bank is used to model the membrane, with each filter associated with a specific point on the basilar membrane.
Since the hair cells produce spike patterns, each filter of the model should also produce a similar spike in the impulse response. The use of a gammatone filter provides an impulse response as the product of a gamma function and a tone. The output of the gammatone filter can be regarded as a measurement of the basilar membrane displacement. Most CASA systems represent the firing rate in the auditory nerve rather than a spike-based. To obtain this, the filter bank outputs are half-wave rectified followed by a square root. (Other models, such as automatic gain controllers have been implemented). The half-rectified wave is similar to the displacement model of the hair cells.
Additional models of the hair cells include the Meddis hair cell model which pairs with the gammatone filter bank, by modeling the hair cell transduction. Based on the assumption that there are three reservoirs of transmitter substance within each hair cell, and the transmitters are released in proportion to the degree of displacement to the basilar membrane, the release is equated with the probability of a spike generated in the nerve fiber. This model replicates many of the nerve responses in the CASA systems such as rectification, compression, spontaneous firing, and adaptation.
Correlogram
Important model of pitch perception by unifying 2 schools of pitch theory:
Place theories (emphasizing the role of resolved harmonics)
Temporal theories (emphasizing the role of unresolved harmonics)
The correlogram is generally computed in the time domain by autocorrelating the simulated auditory nerve firing activity to the output of each filter channel. By pooling the autocorrelation across frequency, the position of peaks in the summary correlogram corresponds to the perceived pitch.
Cross-Correlogram
Because the ears receive audio signals at different times, the sound source can be determined by using the delays retrieved from the two ears. By cross-correlating the delays from the left and right channels (of the model), the coincided peaks can be categorized as the same localized sound, despite their temporal location in the input signal.
The use of interaural cross-correlation mechanism has been supported through physiological studies, paralleling the arrangement of neurons in the auditory midbrain.
Time-Frequency Masks
To segregate the sound source, CASA systems mask the cochleagram. This mask, sometimes a Wiener filter, weighs the target source regions and suppresses the rest. The physiological motivation behind the mask results from the auditory perception where sound is rendered inaudible by a louder sound.
Resynthesis
A resynthesis pathway reconstructs an audio signal from a group of segments. Achieved by inverting the cochleagram, high quality resynthesized speech signals can be obtained.
Applications
Monaural CASA
Monaural sound separation first began with separating voices based on frequency. There were many early developments based on segmenting different speech signals through frequency. Other models followed on this process, by the addition of adaption through state space models, batch processing, and prediction-driven architecture. The use of CASA has improved the robustness of ASR and speech separation systems.
Binaural CASA
Since CASA is modeling human auditory pathways, binaural CASA systems better the human model by providing sound localization, auditory grouping and robustness to reverberation by including 2 spatially separated microphones. With methods similar to cross-correlation, systems are able to extract the target signal from both input microphones.
Neural CASA Models
Since the biological auditory system is deeply connected with the actions of neurons, CASA systems also incorporated neural models within the design. Two different models provide the basis for this area. Malsburg and Schneider proposed a neural network model with oscillators to represent features of different streams (synchronized and desynchronized). Wang also presented a model using a network of excitatory units with a global inhibitor with delay lines to represent the auditory scene within the time-frequency.
Analysis of Musical Audio Signals
Typical approaches in CASA systems starts with segmenting sound-sources into individual constituents, in its attempts to mimic the physical auditory system. However, there is evidence that the brain does not necessarily process audio input separately, but rather as a mixture. Instead of breaking the audio signal down to individual constituents, the input is broken down of by higher level descriptors, such as chords, bass and melody, beat structure, and chorus and phrase repetitions. These descriptors run into difficulties in real-world scenarios, with monaural and binaural signals. Also, the estimation of these descriptors is highly dependent on the cultural influence of the musical input. For example, within Western music, the melody and bass influences the identity of the piece, with the core formed by the melody. By distinguishing the frequency responses of melody and bass, a fundamental frequency can be estimated and filtered for distinction. Chord detection can be implemented through pattern recognition, by extracting low-level features describing harmonic content.
The techniques utilized in music scene analysis can also be applied to speech recognition, and other environmental sounds. Future bodies of work include a top-down integration of audio signal processing, such as a real-time beat-tracking system and expanding out of the signal processing realm with the incorporation of auditory psychology and physiology.
Neural Perceptual Modeling
While many models consider the audio signal as a complex combination of different frequencies, modeling the auditory system can also require consideration for the neural components. By taking a holistic process, where a stream (of feature-based sounds) correspond to neuronal activity distributed in many brain areas, the perception of the sound could be mapped and modeled. Two different solutions have been proposed to the binding of the audio perception and the area in the brain. Hierarchical coding models many cells to encode all possible combinations of features and objects in the auditory scene. Temporal or oscillatory correlation addressing the binding problem by focusing on the synchrony and desynchrony between neural oscillations to encode the state of binding among the auditory features. These two solutions are very similar to the debacle between place coding and temporal coding. While drawing from modeling neural components, another phenomenon of ASA comes into play with CASA systems: the extent of modeling neural mechanisms. The studies of CASA systems have involved modeling some known mechanisms, such as the bandpass nature of cochlear filtering and random auditory nerve firing patterns, however, these models may not lead to finding new mechanisms, but rather give an understanding of purpose to the known mechanisms.
See also
Auditory scene analysis
Blind signal separation
Cocktail party problem
Computational audiology
Machine vision
Speech recognition
Further reading
D. F. Rosenthal and H. G. Okuno (1998) Computational auditory scene analysis. Mahwah, NJ: Lawrence Erlbaum
References
Hearing
Sound
Digital signal processing
Computational fields of study | Computational auditory scene analysis | [
"Technology"
] | 1,942 | [
"Computational fields of study",
"Computing and society"
] |
8,953,976 | https://en.wikipedia.org/wiki/Notepad%2B | Notepad+ is a freeware text editor for Windows operating systems and is intended as a replacement for the Notepad editor installed by default on Windows. It has more formatting features but, like Notepad, works only with plain text. It can open text files of any size, and a single instance of the program can have multiple files open simultaneously. It supports dragging and dropping text within a file and between files, and supports multiple fonts and colours.
Notepad+ is available from the company RogSoft. It was developed by Dutch programmer Rogier Meurs. It was first released in 1996. Originally, it had the advantage of being able to open files of any size, because until 2000 Notepad could not open files larger than 64 KB.
See also
Notepad++
List of text editors
Comparison of text editors
References
External links
RogSoft Homepage (Internet Archive)
Windows text editors
Notepad replacements
Freeware | Notepad+ | [
"Technology"
] | 189 | [
"Computing stubs",
"Software stubs"
] |
8,954,124 | https://en.wikipedia.org/wiki/Blowdown%20stack | A blowdown stack is an elevated vent or vertical stack that is used to vent the pressure of components of a chemical, refinery or other plant if there is a process problem or emergency. A blowdown stack can be used to complement a flare stack or as an alternative. The purpose is to prevent 'loss of containment' of volatile liquids and gases. Blowdown from several systems may be combined in a blowdown header prior to the stack. A knock-out pot may be provided at the base of the stack to remove any liquids. Blowdown stacks may either be ignited (like a flare) or un-ignited (a ‘cold’ vent). The height of the blowdown stack must be tall enough to ensure the safe dispersal of vapour.
Blowdown
Blowdown is the controlled removal, safe flow and disposal of vapour from a pressure vessel. Blowdown, or depressurisation, removes hazardous inventory from a vessel, reduces the pressure in the vessel and thereby reduces the stresses in the vessel walls. Blowdown is used prior to draining of a vessel for maintenance. It is also undertaken in a plant emergency situation to remove and dispose of hazardous material to mitigate the possibility of incident escalation. When pressure vessels are exposed to a fire, the stresses in the vessel walls are increased, potentially leading to rupture; blowdown reduces the stress levels.
Blowdown is through a pipe connected to the vapour space of the vessel. A normally closed actuated blowdown valve (BDV) opens and allows vapour to pass from the vessel to relief system or blowdown stack. BDVs are configured to open in the event of a failure of the control or actuation system. A restriction orifice plate downstream of the BDV ensures the vessel is blowndown in an appropriate time period. For refinery and associated oil and gas systems the requirement is to reduce the pressure to 100 psig (6.9 barg) in 15 minutes. These restrictions ensure that flowrates do not exceed the capacity of the blowdown system and that Joule-Thomson cooling does not increase the stresses in the vessel or blowdown system, potentially leading to brittle fracture.
Incidents
The failure of the blowdown stack to contain hydrocarbons vented from a raffinate splitter led to the catastrophic Texas City refinery explosion in 2005.
See also
Gas flare
Shutdown valve
Piping
Oil production plant
Oil refinery
References
External links
System Failure Case Studies. NASA. January 2008, Volume 2, Special Issue. Retrieved October 9, 2012
Chemical equipment | Blowdown stack | [
"Chemistry",
"Engineering"
] | 514 | [
"Chemical equipment",
"Architecture stubs",
"nan",
"Architecture"
] |
8,954,435 | https://en.wikipedia.org/wiki/Systemic%20%28amateur%20extrasolar%20planet%20search%20project%29 | Systemic is a research project designed to search data for extrasolar planets using amateur astronomers. The project utilizes a downloaded console provided on the Systemic website, allowing users to sort through data sets in search of characteristics which may reveal the presence of a planet within a planetary system.
Volunteers can choose to search simulated or actual planetary systems. The simulations are used to help Systemic gain a deeper understanding of real extrasolar planets. The real Solar System and the Galilean moons of Jupiter's natural satellites (hidden among the "challenge" data sets) are among the more than 450 data sets of real, and 520 simulated, star systems.
The systemic program itself is programmed in Java for ease in running on multiple operating systems. The program is available as an online applet or for download to be run at home.
The program presents a data set for a system and some tools to help analyze the data and some feedback on the "goodness of fit" and "long term stability" of the currently defined system. The data set is the radial velocity derived from doppler measurements of the star (or similar object) over time. Some data sets look like a sinusoidal curve while others seem far more complex. Any radial velocity is presumed to be from the gravitational tug(s) of possibly multiple bodies who combine to create the specific data curve. The reason the program has to manipulated by the user is that the complexities of multi-body orbits are not solvable to unique answers. While some star systems could be resolved to a simple pair of bodies most will not. The systemic software implements several ways of calculating orbital mechanics – from the simplistic Keplerian laws to an implementation of Runge–Kutta methods.
Results one obtains can be uploaded and are analyzed independently for goodness of fit and stability and are posted among the proposed solutions for that system. If a result is found to be unstable it is removed from the list of candidate solutions, though it is possible a particular system really is in a period of transition and instability (presumed to be a rare condition) so great that planets would be ejected from the system.
Example analysis
The default system the systemic software opens with is "14Her" or 14 Herculis. There are some 20 "unique" posted possible solutions with only a general idea of "goodness of fit" to help decide favored solutions (the best solution posted so far is by user EricFDiaz who has a three-planet system to explain the curve of the velocities of the star over time). It must be understood that results from using systemic are not a discovery, just a possible fit to the data. It could be correct, partially correct, or not even in the ballpark of whatever, if anything, is eventually found.
Team
Systemic is designed, and run by:
Greg Laughlin — University of California Santa Cruz
Aaron Wolf — Caltech
Stefano Meschiari — University of California Santa Cruz
Eugenio Rivera — University of California Santa Cruz
Paul Shankland — US Naval Observatory
See also
BOINC
Einstein@Home
Grid computing
Ken Croswell
List of volunteer computing projects
Methods of detecting extrasolar planets
Search for Extra-Terrestrial Intelligence
References
External links
Systemic website
Amateur astronomy
Amateur astronomy organizations
Distributed computing projects
Exoplanet search projects | Systemic (amateur extrasolar planet search project) | [
"Astronomy",
"Engineering"
] | 658 | [
"Exoplanet search projects",
"Distributed computing projects",
"Astronomy organizations",
"Information technology projects",
"Astronomy projects",
"Amateur astronomy organizations"
] |
8,955,468 | https://en.wikipedia.org/wiki/Selenography | Selenography is the study of the surface and physical features of the Moon (also known as geography of the Moon, or selenodesy). Like geography and areography, selenography is a subdiscipline within the field of planetary science. Historically, the principal concern of selenographists was the mapping and naming of the lunar terrane identifying maria, craters, mountain ranges, and other various features. This task was largely finished when high resolution images of the near and far sides of the Moon were obtained by orbiting spacecraft during the early space era. Nevertheless, some regions of the Moon remain poorly imaged (especially near the poles) and the exact locations of many features (like crater depths) are uncertain by several kilometers. Today, selenography is considered to be a subdiscipline of selenology, which itself is most often referred to as simply "lunar science." The word selenography is derived from the Greek word Σελήνη (Selene, meaning Moon) and γράφω graphō, meaning to write.
History
The idea that the Moon is not perfectly smooth originates to at least , when Democritus asserted that the Moon's "lofty mountains and hollow valleys" were the cause of its markings. However, not until the end of the 15th century AD did serious selenography begin. Around AD 1603, William Gilbert made the first lunar drawing based on naked-eye observation. Others soon followed, and when the telescope was invented, initial drawings of poor accuracy were made, but soon thereafter improved in tandem with optics. In the early 18th century, the librations of the Moon were measured, which revealed that more than half of the lunar surface was visible to observers on Earth. In 1750, Johann Meyer produced the first reliable set of lunar coordinates that permitted astronomers to locate lunar features.
Lunar mapping became systematic in 1779 when Johann Schröter began meticulous observation and measurement of lunar topography. In 1834 Johann Heinrich von Mädler published the first large cartograph (map) of the Moon, comprising 4 sheets, and he subsequently published The Universal Selenography. All lunar measurement was based on direct observation until March 1840, when J.W. Draper, using a 5-inch reflector, produced a daguerreotype of the Moon and thus introduced photography to astronomy. At first, the images were of very poor quality, but as with the telescope 200 years earlier, their quality rapidly improved. By 1890 lunar photography had become a recognized subdiscipline of astronomy.
Lunar photography
The 20th century witnessed more advances in selenography. In 1959, the Soviet spacecraft Luna 3 transmitted the first photographs of the far side of the Moon, giving the first view of it in history. The United States launched the Ranger spacecraft between 1961 and 1965 to photograph the lunar surface until the instant they impacted it, the Lunar Orbiters between 1966 and 1967 to photograph the Moon from orbit, and the Surveyors between 1966 and 1968 to photograph and softly land on the lunar surface. The Soviet Lunokhods 1 (1970) and 2 (1973) traversed almost 50 km of the lunar surface, making detailed photographs of the lunar surface. The Clementine spacecraft obtained the first nearly global cartograph (map) of the lunar topography, and also multispectral images. Successive missions transmitted photographs of increasing resolution.
Lunar topography
The Moon has been measured by the methods of laser altimetry and stereo image analysis, including data obtained during several missions. The most visible topographical feature is the giant far-side South Pole-Aitken basin, which possesses the lowest elevations of the Moon. The highest elevations are found just to the northeast of this basin, and it has been suggested that this area might represent thick ejecta deposits that were emplaced during an oblique South Pole-Aitken basin impact event. Other large impact basins, such as the maria Imbrium, Serenitatis, Crisium, Smythii, and Orientale, also possess regionally low elevations and elevated rims.
Another distinguishing feature of the Moon's shape is that the elevations are on average about 1.9 km higher on the far side than the near side. If it is assumed that the crust is in isostatic equilibrium, and that the density of the crust is everywhere the same, then the higher elevations would be associated with a thicker crust. Using gravity, topography and seismic data, the crust is thought to be on average about thick, with the far-side crust being on average thicker than the near side by about 15 km.
Lunar cartography and toponymy
The oldest known illustration of the Moon was found in a passage grave in Knowth, County Meath, Ireland. The tomb was carbon dated to 3330–2790 BC. Leonardo da Vinci made and annotated some sketches of the Moon in c. 1500. William Gilbert made a drawing of the Moon in which he denominated a dozen surface features in the late 16th century; it was published posthumously in De Mondo Nostro Sublunari Philosophia Nova. After the invention of the telescope, Thomas Harriot (1609), Galileo Galilei (1609), and Christoph Scheiner (1614) made drawings also.
Denominations of the surface features of the Moon, based on telescopic observation, were made by Michael van Langren in 1645. Many of his denominations were distinctly Catholic, denominating craters in honor of Catholic royalty and capes and promontories in honor of Catholic saints. The lunar maria were denominated in Latin for terrestrial seas and oceans. Minor craters were denominated in honor of astronomers, mathematicians, and other famous scholars.
In 1647, Johannes Hevelius produced the rival work Selenographia, which was the first lunar atlas. Hevelius ignored the nomenclature of Van Langren and instead denominated the lunar topography according to terrestrial features, such that the names of lunar features corresponded to the toponyms of their geographical terrestrial counterparts, especially as the latter were denominated by the ancient Roman and Greek civilizations. This work of Hevelius influenced his contemporary European astronomers, and the Selenographia was the standard reference on selenography for over a century.
Giambattista Riccioli, SJ, a Catholic priest and scholar who lived in northern Italy authored the present scheme of Latin lunar nomenclature. His Almagestum novum was published in 1651 as summary of then current astronomical thinking and recent developments. In particular he outlined the arguments in favor of and against various cosmological models, both heliocentric and geocentric. Almagestum Novum contained scientific reference matter based on contemporary knowledge, and contemporary educators across Europe widely used it. Although this handbook of astronomy has long since been superseded, its system of lunar nomenclature is used even today.
The lunar illustrations in the Almagestum novum were drawn by a fellow Jesuit educator named Francesco Grimaldi, SJ. The nomenclature was based on a subdivision of the visible lunar surface into octants that were numbered in Roman style from I to VIII. Octant I referenced the northwest section and subsequent octants proceeded clockwise in alignment with compass directions. Thus Octant VI was to the south and included Clavius and Tycho Craters.
The Latin nomenclature had two components: the first denominated the broad features of terrae (lands) and maria (seas) and the second denominated the craters. Riccioli authored lunar toponyms derived from the names of various conditions, including climactic ones, whose causes were historically attributed to the Moon. Thus there were the seas of crises ("Mare Crisium"), serenity ("Mare Serenitatis"), and fertility ("Mare Fecunditatis"). There were also the seas of rain ("Mare Imbrium"), clouds ("Mare Nubium"), and cold ("Mare Frigoris"). The topographical features between the maria were comparably denominated, but were opposite the toponyms of the maria. Thus there were the lands of sterility ("Terra Sterilitatis"), heat ("Terra Caloris"), and life ("Terra Vitae"). However, these names for the highland regions were supplanted on later cartographs (maps). See List of features on the Moon for a complete list.
Many of the craters were denominated topically pursuant to the octant in which they were located. Craters in Octants I, II, and III were primarily denominated based on names from ancient Greece, such as Plato, Atlas, and Archimedes. Toward the middle in Octants IV, V, and VI craters were denominated based on names from the ancient Roman Empire, such as Julius Caesar, Tacitus, and Taruntius. Toward the southern half of the lunar cartograph (map) craters were denominated in honor of scholars, writers, and philosophers of medieval Europe and Arabic regions. The outer extremes of Octants V, VI, and VII, and all of Octant VIII were denominated in honor of contemporaries of Giambattista Riccioli. Features of Octant VIII were also denominated in honor of Copernicus, Kepler, and Galileo. These persons were "banished" to it far from the "ancients," as a gesture to the Catholic Church. Many craters around the Mare Nectaris were denominated in honor of Catholic saints pursuant to the nomenclature of Van Langren. All of them were, however, connected in some mode with astronomy. Later cartographs (maps) removed the "St." from their toponyms.
The lunar nomenclature of Giambattista Riccioli was widely used after the publication of his Almagestum Novum, and many of its toponyms are presently used. The system was scientifically inclusive and was considered eloquent and poetic in style, and therefore it appealed widely to his contemporaries. It was also readily extensible with new toponyms for additional features. Thus it replaced the nomenclature of Van Langren and Hevelius.
Later astronomers and lunar cartographers augmented the nomenclature with additional toponyms. The most notable among these contributors was Johann H. Schröter, who published a very detailed cartograph (map) of the Moon in 1791 titled the Selenotopografisches Fragmenten. Schröter's adoption of Riccioli's nomenclature perpetuated it as the universally standard lunar nomenclature. A vote of the International Astronomical Union (IAU) in 1935 established the lunar nomenclature of Riccioli, which included 600 lunar toponyms, as universally official and doctrinal.
The IAU later expanded and updated the lunar nomenclature in the 1960s, but new toponyms were limited to toponyms honoring deceased scientists. After Soviet spacecraft photographed the far side of the Moon, many of the newly discovered features were denominated in honor of Soviet scientists and engineers. The IAU assigned all subsequent new lunar toponyms. Some craters were denominated in honor of space explorers.
Satellite craters
Johann H. Mädler authored the nomenclature for satellite craters. The subsidiary craters surrounding a major crater were identified by a letter. These subsidiary craters were usually smaller than the crater with which they were associated, with some exceptions. The craters could be assigned letters "A" through "Z," with "I" omitted. Because the great majority of the toponyms of craters were masculine, the major craters were generically denominated "patronymic" craters.
The assignment of the letters to satellite craters was originally somewhat haphazard. Letters were typically assigned to craters in order of significance rather than location. Precedence depended on the angle of illumination from the Sun at the time of the telescopic observation, which could change during the lunar day. In many cases the assignments were seemingly random. In a number of cases the satellite crater was located closer to a major crater with which it was not associated. To identify the patronymic crater, Mädler placed the identifying letter to the side of the midpoint of the feature that was closest to the associated major crater. This also had the advantage of permitting omission of the toponyms of the major craters from the cartographs (maps) when their subsidiary features were labelled.
Over time, lunar observers assigned many of the satellite craters an eponym. The International Astronomical Union (IAU) assumed authority to denominate lunar features in 1919. The commission for denominating these features formally adopted the convention of using capital Roman letters to identify craters and valleys.
When suitable maps of the far side of the Moon became available by 1966, Ewen Whitaker denominated satellite features based on the angle of their location relative to the major crater with which they were associated. A satellite crater located due north of the major crater was identified as "Z". The full 360° circle around the major crater was then subdivided evenly into 24 parts, like a 24-hour clock. Each "hour" angle, running clockwise, was assigned a letter, beginning with "A" at 1 o'clock. The letters "I" and "O" were omitted, resulting in only 24 letters. Thus a crater due south of its major crater was identified as "M".
Reference elevation
The Moon obviously lacks any mean sea level to be used as vertical datum.
The USGS's Lunar Orbiter Laser Altimeter (LOLA), an instrument on NASA's Lunar Reconnaissance Orbiter (LRO), employs a digital elevation model (DEM) that uses the nominal lunar radius of .
The selenoid (the geoid for the Moon) has been measured gravimetrically by the GRAIL twin satellites.
Historical lunar maps
The following historically notable lunar maps and atlases are arranged in chronological order by publication date.
Michael van Langren, engraved map, 1645.
Johannes Hevelius, Selenographia, 1647.
Giovanni Battista Riccioli and Francesco Maria Grimaldi, Almagestum novum, 1651.
Giovanni Domenico Cassini, engraved map, 1679 (reprinted in 1787).
Tobias Mayer, engraved map, 1749, published in 1775.
Johann Hieronymus Schröter, Selenotopografisches Fragmenten, 1st volume 1791, 2nd volume 1802.
John Russell, engraved images, 1805.
Wilhelm Lohrmann, Topographie der sichtbaren Mondoberflaeche, Leipzig, 1824.
Wilhelm Beer and Johann Heinrich Mädler, Mappa Selenographica totam Lunae hemisphaeram visibilem complectens, Berlin, 1834-36.
Edmund Neison, The Moon, London, 1876.
Julius Schmidt, Charte der Gebirge des Mondes, Berlin, 1878.
Thomas Gwyn Elger, The Moon, London, 1895.
Johann Krieger, Mond-Atlas, 1898. Two additional volumes were published posthumously in 1912 by the Vienna Academy of Sciences.
Walter Goodacre, Map of the Moon, London, 1910.
Mary A. Blagg and Karl Müller, Named Lunar Formations, 2 volumes, London, 1935.
Philipp Fauth, Unser Mond, Bremen, 1936.
Hugh P. Wilkins, 300-inch Moon map, 1951.
Gerard Kuiper et al., Photographic Lunar Atlas, Chicago, 1960.
Ewen A. Whitaker et al., Rectified Lunar Atlas, Tucson, 1963.
Hermann Fauth and Philipp Fauth (posthumously), Mondatlas, 1964.
Gerard Kuiper et al., System of Lunar Craters, 1966.
Yu I. Efremov et al., Atlas Obratnoi Storony Luny, Moscow, 1967–1975.
NASA, Lunar Topographic Orthophotomaps, 1978.
Antonín Rükl, Atlas of the Moon, 2004.
Galleries
See also
Gravitation of the Moon
Google Moon
Grazing lunar occultation
Planetary nomenclature
Selenographic coordinate system
List of maria on the Moon
List of craters on the Moon
List of mountains on the Moon
List of valleys on the Moon
References
Citations
Bibliography
External links
NASA Catalogue of Lunar Nomenclature (1982), Leif E. Andersson and Ewen A. Whitaker
The Galileo Project: The Moon
Observing the Moon: The Modern Astronomer's Guide
Lunar control networks (USGS)
The Rise And Fall of Lunar Observing , Kevin S. Jung
Consolidated Lunar Atlas
Virtual exhibition about the topography of the Moon on the digital library of Paris Observatory
Topography
Geodesy
Lunar science
Space science
Selenographers
Cartography | Selenography | [
"Mathematics"
] | 3,422 | [
"Applied mathematics",
"Geodesy"
] |
8,955,535 | https://en.wikipedia.org/wiki/DontDateHimGirl.com | DontDateHimGirl.com is a website with dating advice and tips. It was launched in July 2005. It originally hosted anonymously submitted relationship stories about cheating partners. In 2010, the website said it was removing the "database of alleged cads".
In an article in The New York Times, the site's founder Tasha Cunningham (also known as Tasha Joseph) likened it to a "dating credit report" for women.
History
DontDateHimGirl.com was founded in 2005 by Tasha Joseph. Members were able to post anonymous reviews and photographs of cheating men to the site. When asked about the accuracy of reviews, Joseph said that the website terms and conditions required posted content to be true, and said that men could also join the website to respond to messages.
In July 2010, the site issued a press release that it would be removing the "database of alleged cads" to refocus on "putting out quality content such as articles, videos and podcasts that help women learn to date better, forming content partnerships and creating engaging mobile platforms". As of July 2011, much of the database was still available to be accessed, but as of February 2016 the database has been removed.
Controversies
The site has received criticism as a "reputation management system" which provides a venue for anonymously posting false, malicious or fraudulent profiles of men without an adequate means to correct them.
In 2006, Todd Hollis, a Pennsylvania attorney, filed a suit against the website owner as well as two alleged posters and five unidentified women for various claims posted about him which he asserted were false and defamatory. The lawsuit was initially dismissed in Pennsylvania for a lack of personal jurisdiction. In 2007, Hollis filed a second lawsuit in federal court in Florida which was settled after the federal judge refused to dismiss the new case. The terms of the settlement were not disclosed.
A September 2006 article in the Miami New Times elaborated on a fabricated profile created to demonstrate that the "website is dangerous". The New Times investigated a number of profiles and found claims made were on the whole, fallacious. One profile the New Times uncovered supposedly of a philandering ex-boyfriend was actually a gay man who had spurned a woman's advances.
In an August 2007 feature, ABC News referred to DontDateHimGirl as a "revenge site". On the same day, The O'Reilly Factor referenced DontDateHimGirl as a "hate site".
While it was announced in July 2010 that the profiles of the men on the site would be removed, as of June 2011, the database could still be accessed through the site's "posts" directory which are linked extensively on other websites. However, on an unknown date consequent to this, the database was removed as promised and as of February 2016 is not accessible.
See also
Are We Dating The Same Guy?
Lulu a mobile app with a similar rating system in place for men
References
External links
Zosia Bielski (May 13, 2010). The Globe and Mail.
2005 establishments in the United States
American women's websites
Internet properties established in 2005
Reputation management
Sexuality and computing | DontDateHimGirl.com | [
"Technology"
] | 634 | [
"Computing and society",
"Sexuality and computing"
] |
8,955,537 | https://en.wikipedia.org/wiki/Gravitation%20of%20the%20Moon | The acceleration due to gravity on the surface of the Moon is approximately 1.625 m/s2, about 16.6% that on Earth's surface or 0.166 . Over the entire surface, the variation in gravitational acceleration is about 0.0253 m/s2 (1.6% of the acceleration due to gravity). Because weight is directly dependent upon gravitational acceleration, things on the Moon will weigh only 16.6% (= 1/6) of what they weigh on the Earth.
Gravitational field
The gravitational field of the Moon has been measured by tracking the radio signals emitted by orbiting spacecraft. The principle used depends on the Doppler effect, whereby the line-of-sight spacecraft acceleration can be measured by small shifts in frequency of the radio signal, and the measurement of the distance from the spacecraft to a station on Earth. Since the gravitational field of the Moon affects the orbit of a spacecraft, one can use this tracking data to detect gravity anomalies.
Most low lunar orbits are unstable. Detailed data collected has shown that for low lunar orbit the only "stable" orbits are at inclinations near 27°, 50°, 76°, and 86°. Because of the Moon's synchronous rotation it is not possible to track spacecraft from Earth much beyond the limbs of the Moon, so until the recent Gravity Recovery and Interior Laboratory (GRAIL) mission the far-side gravity field was not well mapped.
The missions with accurate Doppler tracking that have been used for deriving gravity fields are in the accompanying table. The table gives the mission spacecraft name, a brief designation, the number of mission spacecraft with accurate tracking, the country of origin, and the time span of the Doppler data. Apollos 15 and 16 released subsatellites. The Kaguya/SELENE mission had tracking between 3 satellites to get far-side tracking. GRAIL had very accurate tracking between 2 spacecraft and tracking from Earth.
The accompanying table below lists lunar gravity fields. The table lists the designation of the gravity field, the highest degree and order, a list of mission IDs that were analyzed together, and a citation. Mission ID LO includes all 5 Lunar Orbiter missions. The GRAIL fields are very accurate; other missions are not combined with GRAIL.
A major feature of the Moon's gravitational field is the presence of mascons, which are large positive gravity anomalies associated with some of the giant impact basins. These anomalies significantly influence the orbit of spacecraft around the Moon, and an accurate gravitational model is necessary in the planning of both crewed and uncrewed missions. They were initially discovered by the analysis of Lunar Orbiter tracking data: navigation tests prior to the Apollo program showed positioning errors much larger than mission specifications.
Mascons are in part due to the presence of dense mare basaltic lava flows that fill some of the impact basins. However, lava flows by themselves cannot fully explain the gravitational variations, and uplift of the crust-mantle interface is required as well. Based on Lunar Prospector gravitational models, it has been suggested that some mascons exist that do not show evidence for mare basaltic volcanism. The huge expanse of mare basaltic volcanism associated with Oceanus Procellarum does not cause a positive gravity anomaly. The center of gravity of the Moon does not coincide exactly with its geometric center, but is displaced toward the Earth by about 2 kilometers.
Mass of Moon
The gravitational constant G is less accurate than the product of G and masses for Earth and Moon. Consequently, it is conventional to express the lunar mass M multiplied by the gravitational constant G. The lunar GM = 4902.8001 km3/s2 from GRAIL analyses. The mass of the Moon is M = 7.3458 × 1022 kg and the mean density is 3346 kg/m3. The lunar GM is 1/81.30057 of the Earth's GM.
Theory
For the lunar gravity field, it is conventional to use an equatorial radius of R = 1738.0 km. The gravity potential is written with a series of spherical harmonic functions Pnm. The gravitational potential V at an external point is conventionally expressed as positive in astronomy and geophysics, but negative in physics. Then, with the former sign,
where r is the radius to an external point with r ≥ R, φ is the latitude of the external point, and λ is the east longitude of the external point. Note that the spherical harmonic functions Pnm can be normalized or unnormalized affecting the gravity coefficients Jn, Cnm, and Snm. Here we will use unnormalized functions and compatible coefficients. The Pn0 are called Legendre polynomials and the Pnm with m≠0 are called the Associated Legendre polynomials, where subscript n is the degree, m is the order, and m ≤ n. The sums start at n = 2. The unnormalized degree-2 functions are
Note that of the three functions, only P20(±1)=1 is finite at the poles. More generally, only Pn0(±1)=1 are finite at the poles.
The gravitational acceleration of vector position r is
where er, eφ, and eλ are unit vectors in the three directions.
Gravity coefficients
The unnormalized gravity coefficients of degree 2 and 3 that were determined by the GRAIL mission are given in Table 1. The zero values of C21, S21, and S22 are because a principal axis frame is being used. There are no degree-1 coefficients when the three axes are centered on the center of mass.
The J2 coefficient for an oblate shape to the gravity field is affected by rotation and solid-body tides whereas C22 is affected by solid-body tides. Both are larger than their equilibrium values showing that the upper layers of the Moon are strong enough to support elastic stress. The C31 coefficient is large.
Simulating lunar gravity
In January 2022 China was reported by the South China Morning Post to have built a small (60 centimeters in diameter) research facility to simulate low lunar gravity with the help of magnets. The facility was reportedly partly inspired by the work of Andre Geim (who later shared the 2010 Nobel Prize in Physics for his research on graphene) and Michael Berry, who both shared the Ig Nobel Prize in Physics in 2000 for the magnetic levitation of a frog.
See also
Magnetic field of the Moon
Micro-g environment
References
Geodesy
Moon
Lunar science
Gravimetry of objects | Gravitation of the Moon | [
"Mathematics"
] | 1,339 | [
"Applied mathematics",
"Geodesy"
] |
8,955,645 | https://en.wikipedia.org/wiki/Joyce%20Kilmer%20Memorial%20Forest | Joyce Kilmer Memorial Forest is an approximately 3,800-acre tract of publicly owned virgin forest in Graham County, North Carolina, named in memory of poet Joyce Kilmer (1886–1918), best known for his poem "Trees". One of the largest contiguous tracts of old growth forest in the Eastern United States, the area is administered by the U. S. Forest Service. The memorial forest is a popular family hiking destination and features an easy two-mile, figure-eight trail that includes a memorial plaque at the juncture of the two loops. In 1975 the memorial forest was joined with a much larger tract of the Nantahala National Forest to become part of the Joyce Kilmer-Slickrock Wilderness.
History
Beginning in 1915, the Babcock Lumber Company of Pittsburgh operated a standard gauge railroad in the area, logging out roughly two-thirds of the Slickrock Creek watershed before construction of Calderwood Dam threatened to flood the lower part of the railroad. A decline in the price of lumber during the Great Depression also encouraged preservation of the trees.
In 1934 the Bozeman Bulger Post (New York) of the Veterans of Foreign Wars petitioned "that the government of the United States examine its millions of forested acres and set aside a fitting area of trees to stand for all time as a living memorial" to Kilmer, a poet and journalist killed during World War I, whose 1913 poem "Trees" had become a popular favorite. After considering forests throughout the country, the Forest Service decided on an uncut area along Little Santeetlah Creek, which was dedicated as the Joyce Kilmer Memorial Forest on July 30, 1936.
Importance
The memorial is a rare example of old growth cove hardwood forest, a diverse type unique to the Appalachian Mountains. Dominant species are yellow-poplar, oak, basswood, beech, and sycamore. Some trees are over 400 years old, and the oldest yellow-poplars are more than in circumference and stand tall.
Missing is the American chestnut, once the dominant tree of the forest, a victim of the chestnut blight accidentally introduced from Asia during the early twentieth century. Although the last of the Kilmer chestnuts had probably died by the late 1930s, their wood is so rot-resistant that remnants of the massive logs and stumps are still visible. Another more recent loss is that of the giant hemlocks due to an infestation of an exotic insect, the hemlock woolly adelgid. Concerned that a falling limb or tree might injure a visitor, Forest Service managers decided to bring down dead trees near the memorial trail in a way they believed would mimic natural windthrow. In November 2010, the Forest Service blew up the trees with explosives, making the lower loop trail much lighter and drier, thereby changing the environment and creating a public relations challenge.
Images
References
Old-growth forests
Wilderness areas of North Carolina
Protected areas of Graham County, North Carolina
Protected areas established in 1936
Nantahala National Forest | Joyce Kilmer Memorial Forest | [
"Biology"
] | 606 | [
"Old-growth forests",
"Ecosystems"
] |
8,955,738 | https://en.wikipedia.org/wiki/Long-eared%20jerboa | The long-eared jerboa (Euchoreutes naso) is a nocturnal mouse-like rodent with a long tail, long hind legs for jumping, and exceptionally large ears. It is distinct enough that authorities consider it to be the only member of both its genus, Euchoreutes, and subfamily, Euchoreutinae.
Long-eared jerboas are found in the Palearctic ecozone. The specific palearctic ecozone areas they are found in are southernmost Mongolia to the Takla-Makan Desert, Mengxin, Aerijin Mountain, and Qing-Zang Plateau regions of north western China. Long-eared jerboas in most cases are nocturnal, The long-eared jerboa's fur according to the book 100 animals to see before they die "is reddish yellow to pale russet with white underparts." Very little is known about the species.
Description
The long-eared jerboa's head and body length measures to while its tail is double this size, between and . Like its disproportionately long tail, its hind feet are also large, helping it to jump high, measuring between and . It weighs to . Long-eared jerboas usually eat insects. They use sound to locate and capture them by performing fast leaps into the air. According to animal diversity web "The two lateral digits are shorter than the three central ones. The central metatarsals are fused for a small distance. The feet are covered with tufts of bristly hairs. Long-eared jerboas have ears that are 1/3 longer than their heads. The incisors are thin and white. A small premolar can be found on each side of the upper jaw. Females have eight mammae." Their fur is light reddish/brown with a white underside. Their tails are covered in fine hairs the same color as their body and have a black and white tuft on the end.
Conservation
The long-eared jerboa was identified as one of the top-10 "focal species" in 2007 by the Evolutionarily Distinct and Globally Endangered (EDGE) project.
In 2007 Zoological Society of London EDGE of Existence Programme sent a researcher to study human impact on its environment. The study returned with video footage that has been noted as the "first time" the creature has been "recorded on camera". This has helped to start a campaign to protect them.
References
9. www.theanimalfiles.com
External links
EDGE of Existence "(Long-eared jerboa)" Saving the World's most Evolutionarily Distinct and Globally Endangered (EDGE) species
Mammals described in 1891
Dipodidae
EDGE species
Mammals of Mongolia
Rodents of China
Taxa named by William Lutley Sclater | Long-eared jerboa | [
"Biology"
] | 581 | [
"EDGE species",
"Biodiversity"
] |
8,956,408 | https://en.wikipedia.org/wiki/Concrete%20leveling | In civil engineering, concrete leveling is a procedure that attempts to correct an uneven concrete surface by altering the foundation that the surface sits upon. It is a cheaper alternative to having replacement concrete poured and is commonly performed at small businesses and private homes as well as at factories, warehouses, airports and on roads, highways and other infrastructure.
Causes of settlement
Concrete slabs can be susceptible to settlement from a wide variety of factors, the most common being an inconsistency of moisture in the soil. Soil expands and contracts as the levels of moisture fluctuate during the dry and rainy seasons. In some parts of the United States, naturally occurring soils can consolidate over time, including areas ranging from Texas up through to Wisconsin. Soil erosion also contributes to concrete settlement, which is common for locations with improper drainage. Concrete slabs built upon filled-in land can excessively settle as well. This is common for homes with basement levels since the backfill on the outside of the foundation frequently is not compacted properly. In some cases, poorly designed sidewalk or patio slabs direct water towards the basement level of a structure. Tree roots can also have an impact on concrete as well, actually powerful enough to lift a slab upwards or breakthrough entirely; this is common along public roadways, especially within metropolitan areas.
Concrete settlement, uneven concrete surfaces, and uneven footings can also be caused by seismic activity especially in earthquake-prone countries including Japan, New Zealand, Turkey, and the United States.
Slabjacking
"Slabjacking" is a specialty concrete repair technology. In essence, slabjacking attempts to lift a sunken concrete slab by pumping a substance through the concrete, effectively pushing it up from below. The process is also commonly referred to as "mudjacking" and "pressure grouting.”
Accounts of raising large concrete slabs through the use of hydraulic pressure date back to the early 20th century. Early contractors used a mixture of locally available soils (sometimes including crushed limestone and/or cement for strength), producing a "mud-like" substance and thus the term "mudjacking." In recent years, some slabjacking contractors began using expanding polyurethane foam. Each method has its benefits and disadvantages.
The slabjacking process generally starts with drilling access holes in the concrete, strategically located to maximize lift. These holes range in size from 3/8" up to 3" depending on the process used.
Initial material injections fill any under slab void space. Once the void space is filled, subsequent injections will start lifting the concrete within minutes. After the slabs are lifted, the access holes are patched and the work is complete. The process is rapid when compared to traditional remove and replace applications and is minimally disturbing to the surrounding areas.
Slabjacking technology has several benefits, including:
Cost – can be significantly less expensive than new concrete
Timeliness of the repair – concrete is typically usable within hours as opposed to days with new concrete
Minimal or no environmental impact – mostly due to keeping waste out of landfills
Aesthetic – does not disturb the surrounding area and landscaping
Slabjacking also has some limitations, including:
Concrete must be in fairly sound condition – if there are too many cracks, replacement might be the only option
New cracks can occur as the slab is lifted – most would have already been present, just not visible before lifting
Possible resettlement – if concrete poured on top of poorly compacted soils it can still sink further. However, this is also possible with new concrete.
Slabjacking can typically be broken down into three main process types:
Mudjacking
The term Mudjacking originates from using a mixture of topsoil and portland cements injected underground to hydraulically lift concrete slabs. Mudjacking can be achieved with a variety of mixtures. The most common being a local soil or sand blend, mixed with water and cement. Other additives may be included in the mixture for increased "pumpabilitly"/lubrication, improved strength/curing times, or as a filler. Additives that may be present include: clay/bentonite, fly ash, pond sand, pea gravel, masonry cements, or crushed lime. This process typically requires holes between 1" and 2" in diameter. This "mud" is injected under the concrete slabs, oftentimes using a movable pump that can access most slabs. Once the void under the slab is filled, the pressure builds under the slab, lifting the concrete back into place. Once in place, the holes are filled with a color-matching grout.
Benefits of mudjacking:
Low-pressure lifting of slab
Finely controlled lifting of the slab
Possible to achieve higher compressive strength than foam leveling
Budget-friendly
Equipment can access locations at longer distances than poly foam
Environmentally friendly. Accepted at concrete recycling facilities unlike poly foam and does not need to be separated from the concrete
Disadvantages of mudjacking:
Typically shorter warranty periods than what's offered by polyurethane foam contractors.
Requires more clean-up afterward compared to foam leveling
Largest holes of the three main processes
Can be a slower process due to the smaller material volume of the movable cart.
Does not resist erosion or fill voids as well as polyurethane foam.
Limestone grout leveling
This method uses a pulverized limestone, commonly called agricultural lime. mixed with water, and sometimes Portland cement, to create a slurry about the consistency of a thick milkshake. This slurry is pumped hydraulically beneath the slab through 1" holes. Because of its semi-fluid nature, it pushes against itself, filling voids beneath the slab. Once the void is filled, pressure builds, slowly lifting the slab into place. Due to the low pressure of this method, trained professionals are able to control the lift of the concrete slab precisely, without the worry of lifting too far. This also decreases the likelihood of cracking or damaging the slab further. Once the slab is lifted into place, the holes are filled with a color-matching non-shrink grout.
Even though the injection pressure is relatively low, compared to Foam Leveling, Stone Slurry Grout Leveling has a high compressive strength of 240 pounds per square inch. This is equal to 34,560 pounds of lifting force per square foot. With Portland cement added, this can increase to over 6,000 psi or 864,000 pounds per square foot. Once the slurry dries it creates a near-solid stone foundation for the leveled concrete (much like the original stone base the concrete was poured upon.)
Benefits of stone slurry grout leveling
Low-pressure lifting of slabs
Finely controlled lifting of the slab
When the limestone grout dries out, it creates a hard subsurface for the concrete slab
Smaller holes than mudjacking
Highest compressive strength among the three methods
Environmentally friendly
Budget-friendly
Disadvantages of stone slurry grout leveling:
Requires more clean-up afterward compared with foam leveling
Slabs to be lifted must typically be within 100 feet of the truck-based pumping equipment
Larger holes than foam leveling
Without sufficient cement, rainwater can erode limestone leveling materials resulting in re-settlement
Expanding structural foam leveling
Foam leveling uses polyurethane in an injection process. A two-part polymer is injected through a hole less than one inch in diameter. Although the material is injected at a higher pressure than traditional cementitious grouts, the pressure is not what causes the lifting. The expansion of the air bubbles in the injected material below the slab surface performs the actual lifting action as the liquid resin reacts and becomes a structural foam. The material injected below a slab to be lifted will first find weak soils, expanding into them in such a manner as to consolidate and cause sub-soils to become denser and fill any voids below the slab. One inherent property of expanding foams is that they will follow the path of least resistance, expanding in all directions. Another inherent property includes reaching a hydro-insensitive or hydrophobic state when cured with 100% cure times as little as 30 minutes. Closed-cell injections will not retain moisture and are not subject to erosion once in place.
Some closed-cell polymer foams have baseline lifting capabilities of 6,000 lbs per sq. ft. [CONVERT] and leveling procedures have been performed in which loads as high as 125 tons have been lifted and stabilized in a surface area of less than 900 sq. ft. Some foams are even stronger, with compressive strengths of 50 psi and 100 psi in a free rise state. That is equal to 7,200–14,000 lbs. per square ft. [CONVERT] of support.
Benefits of Expanding Structural Foam Leveling
Meets compressive strength requirements when supporting highway slabs
Consumers benefit from longer warranty periods with Polyurethane Foam
Requires less clean up than Mudjacking or Limestone Grout Leveling
Smaller holes
Mobile units can reach areas inaccessible to truck-based equipment
Does not retain moisture
Does not erode when subjected to rainwater
Disadvantages of expanding structural foam leveling:
Requires specially trained technicians to properly install
Greater technical skills required for operations and maintenance of equipment
Intense heat can build up from improper installation of polyurethane
Environmentally un-friendly as polyurethane is a plastic
Potential toxicity of Structural Foam Dust
Can stick to and permanently stain other surrounding surfaces
Derived from crude oil, shipped to refineries, manufacturing plants, consumers and ultimately to job sites creating a negative environmental impact resulting in additional output of and burning of fuel.
Intense heat can build up causing self combustion and flammability of polyurethane from improper installation
References
Concrete | Concrete leveling | [
"Engineering"
] | 1,957 | [
"Structural engineering",
"Concrete"
] |
8,956,685 | https://en.wikipedia.org/wiki/William%20Draper%20Harkins | William Draper Harkins (December 28, 1873 – March 7, 1951) was an American physical chemist, noted for his contributions to surface chemistry and nuclear chemistry. He is also recognized now as one of the first environmental chemists. Harkins researched the structure of the atomic nucleus and was the first to propose the principle of nuclear fusion, four years before Jean Baptiste Perrin published his theory in 1919-20. His findings enabled, among other things, the development of the H-bomb. As a visiting professor with Fritz Haber in 1909, he was introduced to the study of surface tension, and he began work on the theory of solutions and solubility during a visit to MIT in 1909-1910.
Harkins was born in Titusville, Pennsylvania, and graduated with a PhD from Stanford University in 1907. He subsequently taught chemistry at the University of Montana from 1900 to 1912, and then spent the rest of his career at the University of Chicago.
Harkins correctly predicted the existence of the neutron in 1920 (as a proton–electron complex) and was the first to use the word "neutron" in connection with the atomic nucleus. The neutron was detected experimentally by James Chadwick in 1932. In the beginning of the 1930s, Harkins constructed the second ever cyclotron with fellow University of Chicago scientist Robert James Moon, improving greatly on the design of the previous one. From experiments with this, he concluded that the sun might be powered by nuclear fusion. Among other University of Chicago scientists who made use of this cyclotron was Enrico Fermi, who performed neutron diffusion experiments. Since 1978, the magnet yoke of the cyclotron Harkins built has been on display at Fermilab.
Harkins was elected to the United States National Academy of Sciences in 1921 and the American Philosophical Society in 1925.
Among his students were Robert Mulliken, Lyle Benjamin Borst, Calvin Souther Fuller, Martin Kamen, Henry W. Newson, Samuel Allison, and Robert James Moon, Jr. (1911–1989).
Harkins died in Chicago. He is buried at Oak Woods Cemetery.
References
External links
William Draper Harkins Academic Genealogy and List of PhD Students
Guide to the William D. Harkins Papers 1877-1988 at the University of Chicago Special Collections Research Center
1873 births
1951 deaths
People from Titusville, Pennsylvania
American chemists
University of Montana faculty
University of Chicago faculty
Stanford University alumni
People involved with the periodic table
Members of the American Philosophical Society | William Draper Harkins | [
"Chemistry"
] | 508 | [
"Periodic table",
"People involved with the periodic table"
] |
8,956,794 | https://en.wikipedia.org/wiki/11th%20FAI%20World%20Rally%20Flying%20Championship | 11th FAI World Rally Flying Championship took place between September 4–12, 1999 in Ravenna in Italy.
There were 48 crews from 16 countries: Poland (5), South Africa (5), Italy (5), France (4), Czech Republic (4), Slovakia (4), Austria (4), Germany (4), United Kingdom (2), Greece (2), Russia (2), Spain (2), Chile (2), Republic of Macedonia (2), Slovenia (1), Cyprus (1).
Contest
First navigation competition:
Nigel Hopkins / Dale de Klerk - 96 penal points
Janusz Darocha / Zbigniew Chrząszcz - 102 pts
Krzysztof Wieczorek / Wacław Wieczorek - 124 pts
Second navigation competition:
Włodzimierz Skalik / Ryszard Michalski - 166 pts
Jiři Jakes / Lubomir Šťovíček - 106 pts
Janusz Darocha / Zbigniew Chrząszcz - 120 pts
Third navigation competition:
Krzysztof Wieczorek / Wacław Wieczorek - 4 pts
Jerzy Markiewicz / Dariusz Zawłocki - 65 pts
Joël Tremblet / Jose Bertanier - 71 pts
Results
Individual (10 best)
Team
Two best crews were counted (number of penal points):
- 678
- 1268
- 1541
- 2178
- 2554
- 2570
- 3459
- 3972
- 4752
- 6629
- 9198
- 9295
- 9876
- 11952
- 12740
Trivia
All five Polish crews took places in the best ten.
External links
11th FAI World Rally Flying Championship
Rally Flying 11
Fédération Aéronautique Internationale
September 1999 events in Europe
1999 in Italy
Ravenna
Aviation history of Italy | 11th FAI World Rally Flying Championship | [
"Engineering"
] | 387 | [
"Fédération Aéronautique Internationale",
"Aeronautics organizations"
] |
8,956,851 | https://en.wikipedia.org/wiki/Paint%20robot | Industrial paint robots have been used for decades in automotive paint applications.
Early paint robots were hydraulic versions, which are still in use today but are of inferior quality and safety to the latest electronic offerings. The newest robots are accurate and deliver results with uniform film builds and exact thicknesses.
Originally, industrial paint robots were large and expensive, but robot prices have come down to the point that general industry can now afford the same level of automation used by the large automotive manufacturers.
The selection of modern paint robot varies much more in size and payload to allow many configurations for painting items of all sizes.
Painting robots generally have five or six axis motion, three for the base motions and up to three for applicator orientation. These robots can be used in any explosion hazard Class 1 Division 1 environment.
Industrial paint robots are designed to help standardize the distance and path the automatic sprayer takes, thus eliminating the risk of human error caused by manual spraying. Paint robots are often paired with other automatic painting equipment to maximize the efficiency and consistency of the paint finish. Rotational Bell atomizers, other automatic electrostatic or automatic conventional sprayers are mounted on the robot to provide the highest quality finish. Automatic mixing equipment will usually supply the sprayers with paint. This equipment is designed to regulate pressure and flow, which are extremely important in providing consistent paint finish. Varying levels of automatic mixing equipment can also provide features that cut down on paint waste, and energy costs.
History
The worlds first painting robot was developed at Trallfa, a wheelbarrow factory in Bryne, Norway. The development started in 1964 to aid in the painting of the wheelbarrows and to reduce human interaction with toxic paint chemicals. In 1966 the robot was recruited for production in the factory painting the trolleys and wheelbarrows. By 1969 the robot was commercialized as its own product. The first robot, TR2000, was delivered to Swedish Gustavsberg Procelain for enamelling bath tubs.
Painting robots have been around since at least 1985. They were first introduced in the automative industry, including at General Motors' plant in Michigan.
Industrial robots, including painting ones, were created to keep people out of "dangerous" jobs as well as increase productivity. Since their creation, robots have been working side by side with people in manufacturing companies.
In recent years, the painting robot has evolved past industrial use. Many inventors have taken on the idea of creating robots that can create works of art, rather than paint in just a solid color. Besides making them more creative, others have looked for ways to make the robots affordable and accessible for commercial use in places such as interior wall painting.
Uses
Automotive industry
Painting robots are used by vehicle manufacturers to do detailing work on their cars in a consistent and systematic way. Some of these robots are designed with a robotic arm that moves vertically and horizontally, to apply paint on all parts of the car. A patent granted in 1985 to the Mazda Motor Corporation also includes a door handler (a small mechanical hand) that can open and close doors on a vehicle and paint the interior.
Companies like FANUC continue to mass-produce industrial painting robots that are then sold to manufacturers for use. According to FANUC's website, these robots are useful in limiting safety hazard such as the toxicity of paint, reducing wasted materials through consistent application, and increasing productivity.
Robots are used to paint all different sized automotive parts because they can help provide consistent finish from one part to another. They are used for large exterior parts like doors, hoods, wheels, or bumpers, and also used on small interior components like knobs, consoles and glove boxes.
Aerospace and defense
Finish is also extremely important in the aerospace and defense industry. These parts require very precise specifications for safety and performance reasons. Coatings can provide erosion resistance, anti-static dissipation, and even radar evading stealth. For this reason, consistent finish on all parts is vital to ensure continuity throughout.
Aluminum extrusions & panels
Aluminum extrusion can be found in building panels, metal door and window frames, and structural extrusions that are used in the commercial building industry for protecting buildings and increase aesthetic appeal. Many panel and extrusion manufacturers are faced with slim margins. With that, comes pressure to improve quality, continue to reduce costs, produce faster and provide more customization for their consumers. Because of this, many manufacturers in aluminum extrusions and panels are using paint robots and automatic applicators to apply coatings for protection and aesthetics.
Agriculture and construction equipment
Agricultural and construction equipment finish is important because these types of machines face heavy operation in abuse from harsh environments. Coatings help to protect the machines form rust and extend their life cycle. In this industry, product branding plays a big role for many companies trying to differentiate themselves, so high quality finish is a strong factor for many manufacturers.
In order to provide a durable paint coating with strong aesthetic appeal is not an easy task and can involve several layers of different component materials. In an agricultural or construction equipment manufacturer, there are usually multiple pump configurations feeding a plural component proportioning unit that mixes the multiple components of the paint. The proportioner feeds an automatic applicator hooked up to a robot. With several passes with different coatings, consistency is also very important because it minimizes rework and downtime if it is finished right the first time.
Cookware
Cookware technology continues to evolve using different high performance coatings in order to meet the needs of chefs or people cooking at home. Different types of cookware have unique performance requirements. They need to be able to evenly conduct heat, resist abrasion and impact from repeated utensil use, provide non-stick coatings, provide maximum cleaning ability, and have strong aesthetic appeal. The same pan may need to be coated multiple times with different materials to meet all of its performance requirements.
Paint line robots are very useful paired with an automatic applicator in this environment because each part requires multiple passes with different coatings. The performance of the cookware in each of its specific requirements will hinge solely on the quality of finish of each material. Paint robots provide the same spray pattern and paint path on every pass, minimizing rework for badly finished parts.
Cosmetics
There are many different types of containers used in the cosmetic industry. Manufacturers in this industry are concerned with perfect packaging appearance, many using mirror finishes. Any surface imperfections will cause the piece to be rejected or scrapped. The problem is mirror finishes can actually amplify finish imperfections.
In order to reduce rework costs, the base coat needs to be applied to a very consistent and smooth manner with zero variation. This is accomplished by controlling flow rate from the proportioning unit, having fine atomization from the applicator and a very consistent spray pattern provided from a painting robot.
Future
There are multiple ideas people have come up with to increase the presence of painting robots in various industries. One such idea comes from technology professors; an interior wall painting robot. The design aims to make the robots “roller-based” so that it can move freely along walls and apply paint to them. The hope is to get people out of the toxicity of interior painting and decrease the amount of time it takes to finish walls. According to the designers, the robot can be made inexpensively as to make it more commercially available.
CloudPainter is a company that designs robots, whose take on the painting robot shifts from simple filling of color to a robot that has “computational creativity,” and can paint more detailed and original designs. The robot has a 3-D printed paint-head with multiple robotic arms and is programmed with artificial intelligence and deep learning.
A painting robot designed by Shunsuke Kudoh is equipped with fingered hands and stereo vision. It is capable of looking (with a digital camera eye) at an object, then, using its fingers, pick up a paintbrush and copy the object onto a canvas. The robot is relatively small and can paint small things, such as an apple.
Ai-Da, a humanoid robot created by Aidan Meller, is prompted by AI algorithms to create paintings using her robotic arm, a paintbrush, and palette.
Clockwork, a manicurist robot, uses two 3D cameras to paint a fingernail in about 30 seconds.
References
-
Painting | Paint robot | [
"Engineering"
] | 1,684 | [
"Industrial robots"
] |
8,956,942 | https://en.wikipedia.org/wiki/POP%20before%20SMTP | POP before SMTP or SMTP after POP is a method of authentication used by mail server software which helps allow users the option to send e-mail from any location, as long as they can demonstrably also fetch their mail from the same place.
The POP before SMTP approach has been superseded by SMTP Authentication.
Technically, users are allowed to use SMTP from an IP address as long as they have previously made a successful login into the POP service at the same mail hosting provider, from the same address, within a predefined timeout period.
The main advantage of this process is that it was generally transparent to the average user who will be connecting with an email client, which almost always attempted to fetch new mail before sending new mail. The disadvantages include a potentially complex setup for the mail hosting provider (requiring some sort of communication channel between the POP service and the SMTP service) and uncertainty as to how much time users will take to connect via SMTP (to send mail) after connecting to POP.
Those users not handled by this method need to resort to other authorization methods. Also, in cases where users come from externally controlled dynamically assigned addresses, the SMTP server must be careful about not giving too much leeway when allowing unauthorized connections, because of a possibility of race conditions leaving an open mail relay unintentionally exposed.
See also
Simple Mail Transfer Protocol
SMTP AUTH, specified in
Mail submission protocol, specified in
Email authentication
Computer access control protocols | POP before SMTP | [
"Technology"
] | 303 | [
"Computing stubs",
"Computer network stubs"
] |
8,957,070 | https://en.wikipedia.org/wiki/Europe%20bridge | Europe bridge is the name of several bridges in Europe :
In Austria as Europabrücke
Europabrücke, a bridge over the Wipp valley (1963), highest bridge in Europe until 2004 and Millau Viaduct achievement
In Belgium as Pont de l'Europe
Pont de l'Europe in Huy, over the Meuse (1980) see;
In Bulgaria and Romania
New Europe Bridge, over the Danube between Vidin in Bulgaria and Calafat in Romania (2013)
In France as Pont de l'Europe
Pont de l'Europe in Orléans, over the Loire (built in 2000) ;
Pont de l'Europe in Vichy, a dam-bridge over the Allier (1963) see;
Pont de l'Europe in Avignon over the Rhône (1975) see;
Pont de l'Europe between Strasbourg (France) and Kehl (Germany) over the Rhine (1953)
In Germany as Europabrücke
Europabrücke in Koblenz over the Moselle (1974) ;
Europabrücke in Frankfurt am Main carrying Bundesautobahn 5 over the Main (1978) ;
Europabrücke in Hamburg over the Süderelbe (1983) ;
Europabrücke in Kehl and Strasbourg (France); see France
Europabrücke in Kelheim over the Danube;
In Romania, the New Europe Bridge connecting to Bulgaria
In Switzerland as Europabrücke
Europabrücke in Zürich
Europabrücke in Randa, Switzerland, replaced in 2017 by Charles Kuonen Bridge
Bridges | Europe bridge | [
"Engineering"
] | 302 | [
"Structural engineering",
"Bridges"
] |
8,957,775 | https://en.wikipedia.org/wiki/John%20Argyris | Johann Hadji Argyris FRS (Greek: Ιωάννης Χατζι Αργύρης; 19 August 1913 – 2 April 2004) was a Greek pioneer of computer applications in science and engineering, among the creators of the finite element method (FEM), and later Professor at the University of Stuttgart and Director of the Institute of Structural Mechanics and Dynamics in Aerospace Engineering.
Education
He was born in Volos, Greece but the family moved to Athens where he was educated in the Classical Gymnasium.
He studied civil engineering for four years in the National Technical University of Athens and then in the Technische Hochschule in Munich (now Technische Universität München), receiving his Engineering Diploma in 1936.
Following his escape from Nazi Germany he completed his Doctorate at ETH Zurich in 1942.
Career
His first job was at the Gollnow company in Stettin, where he was involved among other things in high radio transmitter masts. In 1943, he joined the research department of the Royal Aeronautical Society in England. Starting from 1949 he was lecturer in aeronautical engineering at the Imperial College London of the University of London, where he assumed a chair in 1955.
In 1959, Argyris was appointed a professor at the Technische Hochschule in Stuttgart (today University of Stuttgart) and director of the Institute of Structural Mechanics and Dynamics in Aerospace Engineering. He created the Aeronautical and Astronautical Campus of the University of Stuttgart as focal point for applications of digital computers and electronics.
Argyris was involved in and developed to a large extent the Finite Element Method along with Ray William Clough and Olgierd Zienkiewicz after an early mathematical pre-working of Richard Courant.
Awards and honours
Argyris was awarded the Royal Aeronautical Society Silver Medal in 1971.
He was elected a Fellow of the Royal Society in March 1986. His nomination reads:
Personal life
When World War II started Argyris was in Berlin the Technische Hochschule (now Technische Universität Berlin). He was arrested and interned accused of passing research secrets to the Allies. However he was saved from execution by Admiral Canaris (also of Greek descent) who arranged his escape. After swimming the Rhine during an air-raid, he made his way to Switzerland. There he entered ETH Zurich to complete his Doctorate.
Argyris died in Stuttgart and is buried in the Sankt Jörgens Cemetery in the city of Varberg, Sweden.
His uncle, Constantin Carathéodory, was a Greek mathematician of the Modern Era.
References
1913 births
2004 deaths
Aerospace engineers
Structural engineers
Academics of Imperial College London
Greek academics
20th-century Greek engineers
Engineering educators
Royal Medal winners
National Technical University of Athens alumni
Technical University of Munich alumni
People from Volos
Fellows of the Royal Society
Royal Aeronautical Society Silver Medal winners
Knights Commander of the Order of Merit of the Federal Republic of Germany
Recipients of the Order of Merit of Baden-Württemberg
Greek expatriates in Germany
ETH Zurich alumni | John Argyris | [
"Engineering"
] | 609 | [
"Structural engineering",
"Aerospace engineering",
"Aerospace engineers",
"Structural engineers"
] |
8,958,365 | https://en.wikipedia.org/wiki/Dacrymyces%20spathularia | Dacrymyces spathularia is a species of fungus in the family Dacrymycetaceae. Basidiocarps (fruit bodies) are gelatinous, frequently spathulate (spoon-shaped), and grow on wood, mainly in the tropics and subtropics. The fungus is edible and is commercially cultivated for use as an additive in the food industry.
Taxonomy
The species was first described as Merulius spathularius by German-American mycologist Lewis David de Schweinitz based on a collection from North Carolina in the United States. It was moved to the newly created genus Dacryopinax by American mycologist G. W. Martin in 1948 in recognition of its fruit bodies' frequently spathulate shape. Microscopically, however, the species is not typical of the genus and this has been confirmed by recent molecular research, based on cladistic analysis of DNA sequences. Dacryopinax spathularia is not closely related to the type species (Dacryopinax elegans) and belongs elsewhere. It has been placed in a widely defined Dacrymyces, but this latter genus still awaits a comprehensive revision.
Description
The fruit bodies of Dacrymyces spathularia are gregarious, often clustered, and have a distinct stipe (stem) and fertile head that is flattened and fan-like (spathulate) or less commonly palmate. They are tough-gelatinous to cartilaginous and yellow to orange, usually tall and between 0.3–1.2 cm wide. Microscopically, the species has cylindrical basidiospores that become septate at maturity, measuring 7–11.5 by 3.5–4.5 μm.
Similar species
It resembles Guepiniopsis buccina and young specimens of Dacrymyces chrysospermus.
Habitat and distribution
Dacrymyces spathularia grows on both rotting coniferous and broadleaf wood; it has even been reported to grow on polyester rugs. It is widely distributed in Asia, Africa, Australia and the Pacific, North and South America, but is not known from Europe.
Uses
Dacryopinax spathularia is edible. The species is commercially cultivated to produce long-chain glycolipids used as a natural preservative in soft drinks. The process involves fermentation of Dacryopinax spathularia using glucose as a carbon source in aerobic submerged culture.
In China fruit bodies are called guìhuā'ěr (桂花耳, literally "sweet osmanthus ear," referring to their resemblance to osmanthus flowers). They are sometimes included in a vegetarian dish called Buddha's delight.
References
External links
Dacrymycetes
Edible fungi
Fungi in cultivation
Fungi of Asia
Fungi of South America
Fungi of North America
Fungi of Australia
Fungi of Africa
Fungi of Colombia
Fungi described in 1822
Taxa named by Lewis David de Schweinitz
Fungus species | Dacrymyces spathularia | [
"Biology"
] | 616 | [
"Fungi",
"Fungus species"
] |
8,958,658 | https://en.wikipedia.org/wiki/European%20Spallation%20Source | The European Spallation Source ERIC (ESS) is a multi-disciplinary research facility currently under construction in Lund, Sweden. Its Data Management and Software Centre (DMSC) is co-located with DTU in Lyngby, Denmark. Its 13 European contributor countries are partners in the construction and operation of the ESS. The ESS is scheduled to begin its scientific user program in 2027, when the construction phase is set to be completed. The ESS will assist scientists in the tasks of observing and understanding basic atomic structures and forces, which are more challenging to do with other neutron sources in terms of lengths and time scales. The research facility is located near the MAX IV Laboratory, which conducts synchrotron radiation research. The construction of the facility began in the summer of 2014 and the first science results are planned for 2027.
During operation, the ESS will use nuclear spallation, a process in which neutrons are liberated from heavy elements by high energy protons. This is considered to be a safer process than uranium fission since the reaction requires an external energy supply which can be stopped easily. This facility is an example of a "long pulse" source (milliseconds). Furthermore, spallation produces more usable neutrons for a given amount of waste heat than fission.
The facility consists of a linear accelerator, in which protons are accelerated and collide with a rotating, helium-cooled tungsten target, generating intense pulses of neutrons. Surrounding the tungsten are baths of cryogenic hydrogen, which feed neutron supermirror guides. It operates similarly to optical fibres, directing the beams of neutrons to experimental stations, where research is performed on a range of materials.
Neutron scattering can be applied to a range of scientific explorations in physics, chemistry, geology, biology, and medicine. Neutrons serve as a probe for revealing the structure and function of matter from the microscopic down to the atomic scale, with the potential for development of new materials and processes.
During the construction, the ESS became a European Research Infrastructure Consortium, or ERIC, on 1 October 2015.
The European Investment Bank made a €50 million investment in the ESS. This investment is supported by InnovFin-EU Finance for Innovators, an initiative established by the EIB Group in collaboration with the European Commission under Horizon 2020, the EU's research and innovation program.
History
When the ISIS neutron source was built in England in 1985, its success in producing indirect images of molecular structures eventually raised the possibility of a far more powerful spallation source. By 1993, the European Neutron Scattering Association began to advocate for the construction of a new spallation source, and the project would eventually become known as the ESS.
Neutron science soon became a critical tool in the development of industrial and consumer products worldwide. So much so that the Organization for Economic Development (OECD), declared in 1999 that a new generation of high-intensity neutron sources should be built, one each in North America, Asia and Europe. Europe's challenge was its diverse collection of national governments, and an active research community numbering in the thousands. In 2001, a European roadmap for developing accelerator driven systems for nuclear waste incineration estimated that the ESS could have the beam ready for users in 2010. A European international task force gathered in Bonn, Germany in 2002 to review the findings and a positive consensus emerged to build ESS. The stakeholders group met a year later to review the task force's progress, and in 2003 a new design concept was adopted that set the course for beginning operations by 2019.
Over the next five years a selection process chose Lund, Sweden as the site of the ESS; the definitive selection of Lund was announced in Brussels, Belgium, on 28 May 2009. On 1 July 2010, the staff and operations of ESS Scandinavia were transferred from Lund University to 'European Spallation Source ESS AB', a limited liability company set up to design, construct and operate the European Spallation Source in Lund. The company's headquarters are situated in central Lund.
ESS became a European Research Infrastructure Consortium, or ERIC, on 1 October 2015. The Founding Members of the European Spallation Source ERIC are the Czech Republic, Denmark, Estonia, France, Germany, Hungary, Italy, Norway, Poland, Spain, Sweden, Switzerland and the United Kingdom.
As of 2013, the estimated cost of the facility will be about €1.843 bn. (or $1.958 bn.) Host nations Sweden and Denmark each plan to cover about half of the sum. However the negotiations about the exact contributions from every partner were still in progress. From 2010 to 30 September 2015, ESS was operated as a Swedish aktiebolag, or AB.
Site selection
Originally, three possible sites for the ESS were under consideration: Bilbao (Spain), Debrecen (Hungary) and Lund (Sweden).
On 28 May 2009, seven countries indicated support for placing ESS in Sweden. Furthermore, Switzerland and Italy indicated that they would support the site in majority. On 6 June 2009, Spain withdrew the Bilbao candidacy and signed a collaboration agreement with Sweden, supporting Lund as the main site, but with key component development work being performed in Bilbao. This effectively settled the location of the ESS; detailed economical negotiations between the participating countries then took place. On 18 December 2009, Hungary also chose to tentatively support ESS in Lund, thus withdrawing the candidacy of Debrecen.
The facility's construction began in early 2014, with an event held in September of that year. The user programme will start in 2027. The site is accessible via Lund tramway, the first new tram system in Sweden in over a century.
The linear accelerator
The ESS uses a linear accelerator (linac) to accelerate a beam of protons from the exit of its ion source at 75 keV to 2 GeV, at the entrance of the accelerator, protons are traveling at ~1% of the speed of light and at the end of the accelerator, they reach a velocity of ~95% speed of light. The accelerator uses both normal conducting and superconducting cavities.
The normal conducting cavities are Radio frequency Quadrupole, RFQ, working at a frequency of 352.21 MHz, and accelerating the proton beam up to an energy of 3.62 MeV. The next structure is a transport line for the medium energy protons, MEBT which transports the beam from the RFQ to the next structure for further acceleration. In the MEBT, the beam properties are measured, the beam is cleaned from the transverse halo around the beam, and also the head and tail of the beam pulse are cleaned using a transversally deflecting electromagnetic chopper. The Drift Tube Linac, DTL, which is the structure downstream of the MEBT accelerates the beam further to ~90 MeV. At this energy, there is a transition from normal conducting cavities to superconducting cavities.
Three families of superconducting cavities accelerate the beam to its final energy of 2 GeV, firstly a section using double-spoke cavities up to an energy of ~216 Mev, then two families of elliptical cavities which are optimized for medium and high energy proton acceleration at a frequency of 704.42 MHz. Following the elliptical cavities, a transfer-line guides the beam to the target, and just before sending the beam to the target for producing spallation neutrons expands the beam and paints the target to dissipate the generated heat over a larger area.
The linac repetition rate is 14 Hz, and the pulses of protons are 2.86 ms long, making the duty factor of the linac 4%. The beam current within the pulse is 62.5 mA, and the average beam current is 2.5 mA.
Except in the RFQ which uses the same structure and field to accelerate and focus the beam, the transverse focusing of the beam of protons is performed using magnetic lenses. In the low energy beam transport, right after the ion source, magnetic solenoids are used, in the DTL permanent quadrupole magnets are used and the rest of the linac uses electromagnetic quadrupoles.
The spallation target and its environmental impact
The ESS source will be built around a solid tungsten target, cooled by helium gas.
Radioactive substances will be generated by the spallation process, but the solid target makes the handling of these materials easier and safer than if a liquid target had been used.
ESS, E.on, and Lunds Energi are collaborating in a project aiming to get the facility to be the world's first completely sustainable large-scale research centre through investment in wind power. The ESS project is expected to include an extension of the Nysted Wind Farm.
Radioactive material storage and transport will be required, but the need is much less than that of a nuclear reactor.
ESS expects to be CO2-neutral.
Recent design improvements will decrease energy usage at ESS.
Neutron Scattering and Imaging Instruments at ESS
The target station is surrounded by instrument halls with scientific instruments placed in four sections in the cardinal directions. In the western section, science instruments are located 156 meters from the center of the target station. The distance is between 50 and 80 meters in the southern one, and the science instruments located closest to the target station are in the northern and eastern sections.
Initially, 15 different scientific instruments will be erected:
Large-scale structures:
ODIN (Imaging)
SKADI (General purpose SANS)
LoKI (Broadband SANS)
FREIA (Horizontal reflectometer)
ESTIA (Vertical reflectometer)
Diffraction:
HEIMDAL (Powder diffractometer)
DREAM (Powder diffractometer)
BEER (Engineering diffractometer)
MAGiC (Magnetism diffractometer)
NMX (Macromolecular diffractometer)
Spectroscopy:
CSPEC (Cold chopper spectrometer)
T-REX (Thermal chopper spectrometer)
BIFROST (Crystal analyser spectrometer)
VESPA (Vibrational spectrometer)
MIRACLES (Backscattering spectrometer)
ESSnuSB
The European Spallation Source neutrino Super Beam (ESSnuSB) project aims to measure leptonic CP violation at the second neutrino oscillation maximum, offering higher sensitivity than the first maximum. After 10 years of data collection, ESSnuSB is expected to cover over 70% of the CP-violating phase range with 5σ confidence level, achieving a precision better than 8° for all δCP values. The ESSnuSB+ extension project focuses on measuring neutrino-nucleus cross-sections in the 0.2–0.6 GeV energy range to address systematic uncertainties . This will be accomplished using two new facilities: a Low Energy nuSTORM (LEnuSTORM) and a Low Energy Monitored Neutrino Beam (LEMNB). The project also includes the development of a target station prototype, a common near detector, and studies on gadolinium-doped water Cherenkov detectors.
See also
ISIS neutron source – Europe's only pulsed spallation source
J-PARC – The world's most powerful spallation source, located in Japan
MAX IV – synchrotron radiation facility in Lund
Spallation Neutron Source
References
Further reading
S. Peggs et al. ESS Technical Design Report , April 2013.
European Spallation Source. European Spallation Source Activity Report 2015, April 2015.
European Spallation Source. Feature Series: The ESS Instrument Suite, 2014–2015.
Hallonsten, O. 2012. Introduction: In pursuit of a Promise. In O. Hallonsten (ed.) In pursuit of a Promise: Perspectives on the political process to establish the European Spallation Source (ESS) in Lund, Sweden (pp. 11–19). Lund: Arkiv Academic Press, 2012, p. 12.
Prolingheuer, N.; Herbst, M.; Heuel-Fabianek, B.; Moormann, R.; Nabbi, R.; Schlögl, B., Vanderborght, J. 2009: Estimating Dose Rates from Activated Groundwater at Accelerator Sites. Nuclear Technology, Vol. 168, No. 3, December 2009, pp. 924–930.
Heuel-Fabianek, B. 2014: Partition Coefficients (Kd) for the Modelling of Transport Processes of Radionuclides in Groundwater (PDF; 9,4 MB) JÜL-Berichte, Forschungszentrum Jülich, Nr. 4375, 2014, ISSN 0944-2952.
T. Parker. ESS Environmental Design Report, January 2013.
External links
European Spallation Source website. The most up-to-date source for information on the ESS project.
Weekly updates of the construction of ESS and live webcams at the construction site.
essworkshop.org – See how the design of instrumentation for a future ESS-Scandinavia is moving forward.
BrightnESS, EU grant project in support of ESS.
SREss, EU grant project in support of ESS.
Buildings and structures in Lund
Lund University
Neutron scattering
Nuclear physics
Neutron facilities
Particle physics facilities
2019 in Sweden
Particle accelerators | European Spallation Source | [
"Physics",
"Chemistry"
] | 2,725 | [
"Scattering",
"Neutron scattering",
"Nuclear physics"
] |
8,958,957 | https://en.wikipedia.org/wiki/Comparison%20of%20Chernobyl%20and%20other%20radioactivity%20releases | This article compares the radioactivity release and decay from the Chernobyl disaster with various other events which involved a release of uncontrolled radioactivity.
Chernobyl compared to background radiation
Natural sources of radiation are prevalent in the environment, and come from cosmic rays, food sources (bananas have a particularly high source due to potassium-40 but all foods contain carbon and thereby carbon-14), radon gas, granite and other dense rocks, and others. The banana equivalent dose is sometimes used in science communication to visualize different levels of ionizing radiation. The collective radiation background dose for natural sources in Europe is about 500,000 man-Sieverts per year. The total dose from Chernobyl is estimated at 80,000 man-sieverts, or roughly 1/6 as much. However, some individuals, particularly in areas adjacent the reactor, received massively higher doses.
Chernobyl's radiation was detectable across Western Europe. Average doses received ranged from 0.02 mrem (Portugal) to 38 mrem (portions of Germany).
Chernobyl compared with an atomic bomb
Far fewer people died as an immediate result of the Chernobyl event than the immediate deaths from radiation at Hiroshima. Chernobyl is eventually predicted to result in up to 4,000 total deaths from cancer, sometime in the future, according to the WHO and create around 41,000 excess cancer according to the International Journal of Cancer, with, depending on treatment, not all cancers resulting in death. Due to the differences in half-life, the different radioactive fission products undergo exponential decay at different rates. Hence the isotopic signature of an event where more than one radioisotope is involved will change with time.
"Compared with other nuclear events: The Chernobyl explosion put 400 times more radioactive material into the Earth's atmosphere than the atomic bomb dropped on Hiroshima; atomic weapons tests conducted in the 1950s and 1960s all together are estimated to have put some 100 to 1,000 times more radioactive material into the atmosphere than the Chernobyl accident."
The radioactivity released at Chernobyl tended to be more long-lived than that released by a bomb detonation hence it is not possible to draw a simple comparison between the two events. Also, a dose of radiation spread over many years (as is the case with Chernobyl) is much less harmful than the same dose received over a short period.
The relative size of the Chernobyl release when compared with the release due to a hypothetical ground burst of a bomb similar to the Fat Man device dropped on Nagasaki.
A comparison of the gamma dose rates due to the Chernobyl accident and the hypothetical nuclear weapon.
The graph of dose rate as a function of time for the bomb fallout was created using a method similar to that of T. Imanaka, S. Fukutani, M. Yamamoto, A. Sakaguchi and M. Hoshi, J. Radiation Research, 2006, 47, Suppl A121-A127. The graph exhibits the same shape as that obtained in the paper. The bomb fallout graph is for a ground burst of an implosion-based plutonium bomb which has a depleted uranium tamper. The fission was assumed to have been caused by 1 MeV neutrons and 20% occurred in the 238U tamper of the bomb. It was assumed, for the sake of simplicity, that no plume separation of the isotopes occurred between the detonation and the deposit of radioactivity. The following gamma-emitting isotopes are modeled 131I, 133I, 132Te, 133I, 135I, 140Ba, 95Zr, 97Zr, 99Mo, 99mTc, 103Ru, 105Ru, 106Ru, 142La, 143Ce, 137Cs, 91Y, 91Sr, 92Sr, 128Sb, and 129Sb. The graph ignores the effects of beta emission and shielding. The data for the isotopes was obtained from the Korean table of the isotopes. The graphs for the Chernobyl accident were computed by an analogous method. Note that in the event of a low altitude or ground burst nuclear detonation that fractionation of the volatile and non volatile radionuclides occurs. Also during the Chernobyl accident, the ratio between the different elements released by the accident changed as a function of time.
A ground burst of a nuclear weapon creates considerably more local deposited fallout than the air bursts used at Hiroshima or Nagasaki. This is due in part to neutron activation of ground soil and greater amounts of soil being sucked into the nuclear fireball in a ground burst than in a high air burst. In the above, neutron activation is neglected, and only the fission product fraction of the total activity resulting from the ground burst is shown.
Chernobyl compared with Tomsk-7
The release of radioactivity which occurred at Tomsk-7 (an industrial nuclear complex located in Seversk rather than the city of Tomsk) in 1993, is another comparison with the Chernobyl release. During reprocessing activities, some of the feed for the second cycle (medium active part) of the PUREX process escaped in an accident involving red oil. According to the IAEA it was estimated that the following isotopes were released from the reaction vessel:
106Ru 7.9 TBq
103Ru 340 GBq
95Nb 11.2 TBq
95Zr 5.1 TBq
137Cs 505 GBq (estimated from the IAEA data)
141Ce 370 GBq
144Ce 240 GBq
125Sb 100 GBq
239Pu 5.2 GBq
The very short-lived isotopes such as 140Ba and 131I were absent from this mixture, and the long-lived 137Cs was at a small concentration. This is because it is not able to enter the tributyl phosphate/hydrocarbon organic phase used in the first liquid-liquid extraction cycle of the PUREX process. The second cycle is normally to clean up the uranium and plutonium product. In the PUREX process, some zirconium, technetium, and other elements are extracted by the tributyl phosphate. Due to the radiation induced degradation of tributyl phosphate, the first cycle organic phase is always contaminated with ruthenium (later extracted by dibutyl hydrogen phosphate). Because the very short-lived radioisotopes and the relatively long-lived caesium isotopes are either absent or in low concentrations, the shape of the dose rate vs. time graph is different from Chernobyl, both for short times and long times after the accident.
The size of the radioactive release at Tomsk-7 was much smaller, and while it caused moderate environmental contamination, it did not cause any early deaths.
Chernobyl compared to Fukushima Daiichi
Chernobyl compared with the Goiânia accident
While both events released 137Cs, the isotopic signature for the Goiânia accident was much simpler. It was a single isotope which has a half-life of about 30 years. To show how the activity vs. time graph for a single isotope differs from the dose rate due to Chernobyl (in the open air), the adjacent chart is shown with calculated data for a hypothetical release of 106Ru.
Chernobyl compared with the Three Mile Island accident
Three Mile Island-2 was an accident of a completely different type from Chernobyl. However, both accidents have vague similarities.
Chernobyl was a design flaw-caused power excursion causing a steam explosion resulting in a graphite fire, uncontained, which lofted radioactive smoke high into the atmosphere; TMI was a slow, undetected leak – caused by the technical malfunction of a pilot-operated relief valve – which lowered the water level around the nuclear fuel, resulting in over a third of it shattering when refilled rapidly with coolant.
Similar to Chernobyl, operator error played a role but did not directly cause the accident. Both accidents had grueling and costly cleanup efforts. Chernobyl and TMI's unaffected reactors were restarted and continued operation until 2000 and 2019, respectively.
Unlike Chernobyl, TMI-2's reactor vessel did not fail and contained almost all of the radioactive material. Containment at TMI was not breached. On the day of the accident, a small "hydrogen burn" occurred inside the reactor building, but it was not enough to affect normal operation of the reactor.
Following the accident, an estimated 44,000 curies of radioactive gases – particularly Krypton-85 – from the leak were vented into the atmosphere through specially designed filters under operator control. A government report concluded that the accident caused no increase in cancer rates for local residents.
Chernobyl compared with criticality accidents
During the time between the start of the Manhattan project and the present day, a series of accidents have occurred in which nuclear criticality has played a central role. The criticality accidents may be divided into two classes. For more details see nuclear and radiation accidents. A review of the topic was published in 2000, "A Review of Criticality Accidents" by Los Alamos National Laboratory (Report LA-13638), May 2000. Coverage includes United States, Russia, United Kingdom, and Japan. Also available at , which also tries to track down documents referenced in the report.
Press release on a report on criticality accidents from Los Alamos National Laboratory
List of radiation accidents
U.S. report from 1971 on criticality accidents to date
Process accidents
In the first class (process accidents) during the processing of fissile material, accidents have occurred when a critical mass has been created by accident. For instance at Charlestown, Rhode Island, United States, on July 24, 1964, one death occurred. At Tokaimura, Japan, nuclear fuel reprocessing plant, on September 30, 1999, two deaths and one non fatal overexposure occurred as result of accidents where too much fissile matter was placed in a vessel. Radioactivity was released as a result of the Tokaimura accident. The building in which the accident occurred was not designed as a containment building, yet it was able to retard the spread of radioactivity. Because the temperature rise in the nuclear reaction vessel was small, the majority of the fission products remained in the vessel.
These accidents tend to lead to very high doses due to direct irradiation of the workers within the site, but due to the inverse square law the dose suffered by members of the general public tends to be very small. Also very little environmental contamination normally occurs as a result of these accidents.
Reactor accidents
In this type of accident a reactor or other critical assembly releases far more fission power than was expected, or it becomes critical at the wrong moment in time. The series of examples of such events include one in an experimental facility in Buenos Aires, Argentina, on September 23, 1983 (one death), and during the Manhattan Project several people were irradiated (two, Harry Daghlian and Louis Slotin, were irradiated fatally) during "tickling the dragon's tail" experiments. These accidents tend to lead to very high doses due to direct irradiation of the workers within the site, but due to the inverse square law the dose suffered by members of the general public tends to be very small. Also, very little environmental contamination normally occurs as a result of these accidents. For instance, at Sarov the radioactivity remained confined to within the actinide metal objects which were part of the experimental system, according to the IAEA report (2001). Even the SL-1 accident (RIA, power surge in an experimental nuclear reactor in Idaho, 1961) failed to release much radioactivity outside the building in which it occurred.
See also
Church Rock uranium mill spill
Comparison of Fukushima and Chernobyl nuclear accidents
Effects of the Chernobyl disaster
Fukushima nuclear accident
Mayak explosion
International Nuclear Event Scale
Nuclear power debate
List of Chernobyl-related articles
Chernobyl
References
Environmental impact of nuclear power
Chernobyl | Comparison of Chernobyl and other radioactivity releases | [
"Technology"
] | 2,464 | [
"Aftermath of the Chernobyl disaster",
"Environmental impact of nuclear power",
"Civilian nuclear power accidents"
] |
8,960,053 | https://en.wikipedia.org/wiki/Declared%20Rare%20and%20Priority%20Flora%20List | The Declared Rare and Priority Flora List is the system by which Western Australia's conservation flora are given a priority. Developed by the Government of Western Australia's Department of Environment and Conservation, it was used extensively within the department, including the Western Australian Herbarium. The herbarium's journal, Nuytsia, which has published over a quarter of the state's conservation taxa, requires a conservation status to be included in all publications of new Western Australian taxa that appear to be rare or endangered.
The system defines six levels of priority taxa:
X: Threatened (Declared Rare Flora) – Presumed Extinct Taxa These are taxa that are thought to be extinct, either because they have not been collected for over 50 years despite thorough searching, or because all known wild populations have been destroyed. They have been declared as such in accordance with the Wildlife Conservation Act 1950, and are therefore afforded legislative protection under that act.
T: Threatened (Declared Rare Flora) – Extant Taxa These are taxa that have been thoroughly surveyed, and determined to be rare, in danger of extinction, or otherwise in need of special protection. They have been declared rare in accordance with the Wildlife Conservation Act 1950, and are therefore afforded legislative protection under that act. The code for this category was previously 'R'.
P1: Priority One – Poorly Known Taxa These are taxa that are known from only a few (generally less than five) populations, all of which are under immediate threat. They are candidates for declaration as rare flora, but are in need of further survey.
P2: Priority Two – Poorly Known Taxa These are taxa that are known from only a few (generally less than five) populations, some of which are not thought to be under immediate threat. They are candidates for declaration as rare flora, but are in need of further survey.
P3: Priority Three – Poorly Known Taxa That are taxa that are known from several populations, some of which are not thought to be under immediate threat. They are candidates for declaration as rare flora, but are in need of further survey.
P4: Priority Four – Rare Taxa These are taxa that have been adequately surveyed, and are rare but not known to be under threat.
See also
Conservation status
Wildlife Conservation Act 1950, state legislation
Environment Protection and Biodiversity Conservation Act 1999, federal legislation
ROTAP (Rare or Threatened Australian Plants) coding system
References
"Nuytsia – WA's Journal of Systematic Botany". Department of Environment and Conservation, Government of Western Australia.
"Nuytsia – WA's Journal of Systematic Botany - Editorial Guidelines". Department of Environment and Conservation, Government of Western Australia.
External links
Threatened plants – Government of Western Australia
Nature conservation in Western Australia
Biota by conservation status
Botany in Australia | Declared Rare and Priority Flora List | [
"Biology"
] | 550 | [
"Biota by conservation status",
"Biodiversity"
] |
8,960,168 | https://en.wikipedia.org/wiki/PalmPilot%20Professional | The PalmPilot Professional is a personal digital assistant. While the PalmPilot was released March 10, 1997 as an updated version of the Pilot 5000, there was delayed general availability of the Professional model in the marketplace.
It was marketed with a compact design, a back-lit display and the ability to quickly connect to a Microsoft Windows or Macintosh personal computer. it has the ability to synchronize via its cradle (or through a modem, which was sold separately) to a computer, making it possible to send e-mails, set appointments with others, and set contact information. Various third party applications, such as upIRC, enabled connecting to various messaging systems, including most popular instant messaging services. An optional memory card with an IR port was available as an upgrade directly from Palm.
System Details
Operating System: Palm OS 2.0, upgradeable to Palm OS 2.0.5 with 1MB or Palm OS 3.0 if 2MB memory upgrade is installed.
Processor: Motorola MC68328 DragonBall
Internal RAM: 1 MB
Screen Resolution: 160x160 pixels
Battery Type: 2 AAAs
Battery Life: 30 hours
Size: 117 x 81 x 17 mm - 4.6 x 3.2 x 0.7 in.
Weight:
References
Palm OS devices
Computer-related introductions in 1997
Products introduced in 1997
68k-based mobile devices | PalmPilot Professional | [
"Technology"
] | 280 | [
"Mobile computer stubs",
"Mobile technology stubs"
] |
8,960,255 | https://en.wikipedia.org/wiki/Design%20history | Design history is the study of objects of design in their historical and stylistic contexts. With a broad definition, the contexts of design history include the social, the cultural, the economic, the political, the technical and the aesthetic. Design history has as its objects of study all designed objects including those of architecture, fashion, crafts, interiors, textiles, graphic design, industrial design and product design. Design theorists revamp historical techniques and they use these aspects to create more sophisticated techniques of design. It acts as a tool to better future aspects of design.
Design history has had to incorporate criticism of the 'heroic' structure of its discipline in response to the establishment of material culture, much as art history has had to respond to visual culture (although visual culture has been able to broaden the subject area of art history through the incorporation of the televisual, film and new media). Design history has done this by shifting its focus towards the acts of production and consumption. The acts of production and consumption in design history were a result of the modernist approach designers started to take which advanced in the 19th century. Pre-capitalism and feudalism were the main drivers of modernism. They facilitated stylistic features and aesthetics which were exclusive because of the influence of small wealthy elites.
Design history as a component of British practice-based courses
Design history also exists as a component of many practice-based courses.
The teaching and study of design history within art and design programs in Britain are one of the results of the National Advisory Council on Art Education in the 1960s. Among its aims was making art and design education a legitimate academic activity, to which ends a historical perspective was introduced. This necessitated the employment or 'buying in' of specialists from art history disciplines, leading to a particular style of delivery: "Art historians taught in the only way that art historians knew how to teach; they switched off the lights, turned on the slide projector, showed slides of art and design objects, discussed and evaluated them and asked (art and design) students to write essays – according to the scholarly conventions of academia".
The most obvious effect of the traditional approach design history as sequential, in which X begat Y and Y begat Z. This has pedagogical implications in that the realization that assessment requires a fact-based regurgitation of received knowledge leads students to ignore discussions of the situations surrounding a design's creation and reception and to focus instead on simple facts such as who designed what and when.
This 'heroic/aesthetic' view – the idea that there are a few great designers who should be studied and revered unquestioningly – arguably instills an unrealistic view of the design profession. Although the design industry has been complicit in promoting the heroic view of history, the establishment of the UK government of Creative & Cultural Skills has led to calls for design courses to be made less 'academic' and more attuned to the 'needs' of the industry. Design history, as a component of design courses, is under increasing threat in the UK at least and it has been argued that its survival depends on an increased focus on the study of the processes and effects of design rather than the lives of designers themselves.
Ultimately it appears that design history for practice-based courses is rapidly becoming a branch of social and cultural studies, leaving behind its art historical roots. This has led to a great deal of debate as the two approaches forge distinct pedagogical approaches and philosophies.
Debates over the merits of different approaches to teaching design history on practice-based courses
The debate over the best way to approach the teaching of design history to practice-based students is often heated. It is notable that the biggest push to adopt a 'realistic' approach (i.e. non-hero-based and analysing the production as well as the consumption of design that would otherwise be viewed as ephemeral) comes from teachers delivering these programmes, while critics are predominantly those who teach design history by approaching it in a more diverse and geographical standpoint.
The biggest criticism of the 'realistic' approach appears to be that it imposes anonymity on designers, while the counter argument is that the vast majority of designers are anonymous and that it is the uses and users of design that are more important.
The research literature suggests that, contrary to critics' predictions of the death of design history, this realistic approach is beneficial. Baldwin and McLean at the University of Brighton (now at the University of Dundee and Edinburgh College of Art respectively) reported attendance figures for courses using this model rising dramatically, and improved interest in the subject, as did Rain at Central St. Martin's. This compares with the often-reported low attendance and low grades of practice-based students facing the 'death by slideshow' model.
Design history from a global perspective
The rise of western cultures in the 19th century facilitated the idea of having European civilization as culturally advanced which disregarded non-western cultures by representing them as cultures without history. A global perspective of design history meant that there was a growth in understanding design history from a global context. This meant that there became different understandings of design history and acknowledging its processes, production and consumption based on the different cultural contexts. This was done through what is called globalization. One way this was done was by building on to the existing modernist knowledge from Europe and making the processes, production and consumption meet the standards of the different cultures. The problem with this idea is that it assumes that there is only one narrative of design history by limiting it to a specific place and time. Globalizing design history also means popularizing other forms of design that may not constitute as design in the western countries. This means moving beyond the modernists approaches and acknowledging other forms of design other than those based on the European understanding of production and consumption. Such practices ensures that design history from different cultures is acknowledged and is treated equally to that of the West.
Globalization has also meant that design history is no longer only looked at in the perspective of production and consumption but is now also perceived in the lens of theories, policies, social programs, opinions and organizational systems. This perspective allows for acknowledging that design is not only concerned with the materialistic or three-dimensional products, but also includes a wide range of artifacts. Some of these artifacts may be understanding design history as a feature that gives humans a history of ideas on how to live and interact with each other. Aspects such as teamwork, management style and appreciation of different types of creativity are all examples of design history that demonstrates the art of living and interacting with each other. Diversity acts as a form of design technique that is used to facilitate creativity. Having diverse opinions and perspectives allows for a clash in opinions which also enhances creativity and helps build new knowledge. The Chinese design history and design studies has taken this approach by diversifying its approach on design. They take into consideration the Chinese civilizations which includes its history of arts, crafts and philosophy as well as incorporate the western technologies and marketing structures. On the other hand, places in Southern Africa have used design techniques as a form of social communication. These areas used rock paintings as a form of communications and such communication started to advance with the development of pictographs and alphabets.
Museums
Design Museum, London, UK.
V&A Museum, London, UK.
Cooper Hewitt National Design Museum, Smithsonian Museum, NY, USA.
See also
Design History Society
References
External links
Design History Society
Design Is History
Graphic design
Fashion design
Product design
Industrial design | Design history | [
"Engineering"
] | 1,511 | [
"Industrial design",
"Design engineering",
"Fashion design",
"Design history",
"Product design",
"Design"
] |
8,960,391 | https://en.wikipedia.org/wiki/Journal%20of%20Applied%20Behavior%20Analysis | The Journal of Applied Behavior Analysis (JABA) is a quarterly peer-reviewed academic journal which publishes empirical research related to applied behavior analysis. It was established in 1968 and is published by Wiley-Blackwell on behalf of the Society for the Experimental Analysis of Behavior. The editor-in-chief is John Borrero.
Common areas of research in JABA include: functional analysis and treatment of severe behavior disorders, classroom instruction in secondary and higher education, early and intensive behavioral interventions for children with autism, voucher-based contingency management in the treatment of substance abuse, and pediatric feeding therapy. According to the journal's web site, article acceptance rate was 26% in 2023.
Abstracting and indexing
The journal is abstracted and indexed in:
See also
Journal of the Experimental Analysis of Behavior
Florence DiGennaro Reed
References
External links
Journal Homepage
Editorial Board
Behaviorism journals
Delayed open access journals
Academic journals established in 1968
Quarterly journals
Wiley-Blackwell academic journals
Psychotherapy journals | Journal of Applied Behavior Analysis | [
"Biology"
] | 199 | [
"Behavior",
"Behaviorism",
"Behaviorism journals"
] |
8,960,415 | https://en.wikipedia.org/wiki/Exonic%20splicing%20enhancer | In molecular biology, an exonic splicing enhancer (ESE) is a DNA sequence motif consisting of 6 bases within an exon that directs, or enhances, accurate splicing of heterogeneous nuclear RNA (hnRNA) or pre-mRNA into messenger RNA (mRNA).
Introduction
Short sequences of DNA are transcribed to RNA; then this RNA is translated to a protein. A gene located in DNA will contain introns and exons. Part of the process of preparing the RNA includes splicing out the introns, sections of RNA that do not code for the protein. The presence of exonic splicing enhancers is essential for proper identification of splice sites by the cellular machinery.
Role in splicing
SR proteins bind to and promote exon splicing in regions with ESEs, while heterogeneous ribonucleoprotein particles (hnRNPs) bind to and block exon splicing in regions with exonic splicing silencers. Both types of proteins are involved in the assembly and proper functioning of spliceosomes.
During RNA splicing, U2 small nuclear RNA auxiliary factor 1 (U2AF35) and U2AF2 (U2AF65) interact with the branch site and the 3' splice site of the intron to form the lariat. It is thought that SR proteins that bind to ESEs promote exon splicing by increasing interactions with U2AF35 and U2AF65.
Mutation of exonic splicing enhancer motifs is a significant contributor to genetic disorders and some cancers. Simple point mutations in ESEs can inhibit affinity for splicing factors and alter alternative splicing, leading to altered mRNA sequence and protein translation. A field of genetic research is dedicated to determining the location and significance of ESE motifs in vivo.
Research
Computational methods were used to identify 238 candidate ESEs. ESEs are clinically significant because synonymous point mutations previously thought to be silent mutations located in an ESEs can lead to exon skipping and the production of a non functioning protein.
Disruption of an exon splicing enhancer in exon 3 of MLH1 gene is the cause of HNPCC (hereditary nonpolyposis colorectal cancer) in a Quebec family.
There is evidence that these 236 hexamers that signal splicing are evolutionarily conserved.
See also
Exonic splicing silencer (ESS)
References
External links
ESE finder
Genetics | Exonic splicing enhancer | [
"Biology"
] | 509 | [
"Genetics"
] |
8,960,524 | https://en.wikipedia.org/wiki/Double%20Cluster | The Double Cluster (also known as Caldwell 14) consists of the open clusters NGC 869 and NGC 884 (often designated h Persei and χ (chi) Persei, respectively), which are close together in the constellation Perseus. Both visible with the naked eye, NGC 869 and NGC 884 lie at a distance of about 7,500 light years in the Perseus Arm of the Milky Way galaxy.
Membership
NGC 869 has a mass of 4,700 solar masses and NGC 884 weighs in at 3,700 solar masses; both clusters are surrounded with a very extensive halo of stars, with a total mass for the complex of at least 20,000 solar masses. They form the core of the Perseus OB1 association of young hot stars.
Based on their individual stars, the clusters are relatively young, both 14 million years old. In comparison, the Pleiades have an estimated age ranging from 75 million years to 150 million years.
There are more than 300 blue-white super-giant stars in each of the clusters. The clusters are also blueshifted, with NGC 869 approaching Earth at a speed of and NGC 884 approaching at a similar speed of . Their hottest main sequence stars are of spectral type B0. NGC 884 includes five prominent red supergiant stars, all variable and all around 8th magnitude: RS Persei, AD Persei, FZ Persei, V403 Persei, and V439 Persei.
History
Greek astronomer Hipparchus cataloged the object (a patch of light in Perseus) as early as 130 BCE. To Bedouin Arabs the cluster marked the tail of the smaller of two fish they visualized in this area, and it was shown on illustrations in Abd al-Rahman al-Sufi's Book of Fixed Stars. However, the true nature of the Double Cluster was not discovered until the invention of the telescope, many centuries later. In the early 19th century William Herschel was the first to recognize the object as two separate clusters. The Double Cluster is not included in Messier's catalog, but is included in the Caldwell catalogue of popular deep-sky objects.
The clusters were designated h Persei and χ Persei by Johann Bayer in his Uranometria (1603). It is sometimes claimed that Bayer did not resolve the pair into two patches of nebulosity, and that χ refers to the Double Cluster and h to a nearby star. Bayer's Uranometria chart for Perseus does not show them as nebulous objects, but his chart for Cassiopeia does, and they are described as Nebulosa Duplex in Schiller's Coelum Stellatum Christianum, which was assembled with Bayer's help.
Location
The Double Cluster is circumpolar (continuously above the horizon) from most northern temperate latitudes. It is in proximity to the constellation Cassiopeia. This northern location renders this object invisible from locations south of about 30º south latitude, such as New Zealand, most of Australia and South Africa. The Double Cluster is approximately the radiant of the Perseid meteor shower, which peaks annually around August 12 or 13. Although easy to locate in the northern sky, observing the Double Cluster in its two parts requires optical aid. They are described as being an "awe-inspiring" and "breathtaking" sight, and are often cited as a target in astronomy observer's guides.
Mythology
Perseus was a famous hero of Greek mythology, a son of the Greek god Zeus. Along with beheading Medusa, Perseus performed other heroic deeds such as saving princess Andromeda who was chained to a rock as a sacrifice to a sea monster, Cetus. The gods commemorated Perseus by placing him among the stars, with the head of Medusa in one hand and the jeweled sword in the other. The Double Cluster represents the jeweled handle of his sword.
References
External links
Open clusters
014b
Asterisms (astronomy)
Astronomical objects known since antiquity | Double Cluster | [
"Astronomy"
] | 829 | [
"Sky regions",
"Constellations",
"Asterisms (astronomy)"
] |
8,960,940 | https://en.wikipedia.org/wiki/Earth%20Point | EarthPoint.us maps southwest Idaho real estate listings onto Google Earth and Google Maps.
Earth Point also maps the United States Public Land Survey System onto Google Earth.
Features
Properties are located with roof-top accuracy without relying on geocoding.
Property lines are drawn.
Properties are defined by ESRI shape files produced by county assessor offices. These files are converted by Earth Point for use on Google Earth and Google Maps.
Property for Sale - maps MLS listings in Ada and Canyon counties, Idaho.
County Assessor Data - maps any property in Ada or Canyon counties, whether or not it is for sale. Displays county assessor information including address, legal description, and assessed value. For Ada county, displays a picture of the property and the zoning.
Township and Range - maps the United States Public Land Survey System onto Google Earth.
Excel To Kml - upload spreadsheet data onto Google Earth.
References
External links
Earth Point web-site
Companies based in Idaho
Geographic information systems
Real estate companies of the United States
Online financial services companies of the United States
Land surveying systems
Companies with year of establishment missing | Earth Point | [
"Technology"
] | 222 | [
"Information systems",
"Geographic information systems"
] |
8,961,469 | https://en.wikipedia.org/wiki/Principles%20of%20user%20interface%20design | The principles of user interface design are intended to improve the quality of user interface design. According to Lucy Lockwood's approach of usage-centered design, these principles are:
The structure principle: Design should organize the user interface purposefully, in meaningful and useful ways based on clear, consistent models that are apparent and recognizable to users, putting related things together and separating unrelated things, differentiating dissimilar things and making similar things resemble one another. The structure principle is concerned with overall user interface architecture.
The simplicity principle: The design should make simple, common tasks easy, communicating clearly and simply in the user's own language, and providing good shortcuts that are meaningfully related to longer procedures.
The visibility principle: The design should make all needed options and materials for a given task visible without distracting the user with extraneous or redundant information. Good designs don't overwhelm users with alternatives or confuse with unneeded information.
The feedback principle: The design should keep users informed of actions or interpretations, changes of state or condition, and errors or exceptions that are relevant and of interest to the user through clear, concise, and unambiguous language familiar to users.
The tolerance principle: The design should be flexible and tolerant, reducing the cost of mistakes and misuse by allowing undoing and redoing, while also preventing errors wherever possible by tolerating varied inputs and sequences and by interpreting all reasonable actions reasonable.
The reuse principle: The design should reuse internal and external components and behaviors, maintaining consistency with purpose rather than merely arbitrary consistency, thus reducing the need for users to rethink and remember.
According to Jef Raskin there are two laws of user interface design:
First Law: A computer shall not harm your work or, through inactivity, allow your work to come to harm.
Second Law: A computer shall not waste your time or require you to do more work than is strictly necessary.
Additionally he mentions that "users should set the pace of an interaction", meaning that a user should not be kept waiting unnecessarily and that an interface should be monotonous with no surprises "the principle of monotony".
See also
Mental model
The Design of Everyday Things
References
2. https://learning.oreilly.com/library/view/software-for-use/9780768685305/
3. https://musemind.agency/blog/user-interface-design-principles
Design
Graphic design | Principles of user interface design | [
"Technology"
] | 512 | [
"User interfaces",
"Interfaces"
] |
8,963,187 | https://en.wikipedia.org/wiki/Omni-Theatre%2C%20Science%20Centre%20Singapore | The Omni-Theatre is an observatory and large-format film theatre located at the Science Centre Singapore (formerly Singapore Science Centre) in Jurong East, Singapore.
Facilities
It was officially opened on 10 December 1987 by the 4th President of Singapore Wee Kim Wee as an expansion of the larger Science Centre, it specifically encompasses an observatory, an omniplanetarium, and a domed projection system to show movies relating to science, astronomy, etc. A simulation theatre, exhibition room, classroom, restaurant, and gift shop are also located on the premises.
The Observatory
As one of the few observatories in the world located next to the Equator, constellations in both the northern and southern celestial hemispheres can be observed and thus opens up more vistas in the sky for observers.
The main telescope of the Observatory is a 40-cm Cassegrain reflector of combined focal length 520-cm. The sub-telescope is a 15-cm apochromatic Kepler refractor of focal length 180-cm. The equatorial mount for the telescopes was designed for its location; the accompanying English yoke provides the necessary stability for the drive and tracking mechanisms. The 5.5-metre stainless steel dome can be made to swivel in any direction and its shutter can be made to slide open for the telescope to be focused onto interesting objects in the sky.
The observatory is situated at geographical coordinates:
1° 20' 03" N latitude
103° 44' 14" E longitude
15.27 m Height (m.s.l)
The theatre
The theatre consists of a massive hemispheric screen, twenty-three metres in diameter. This screen is sixteen metres or about five storeys high, and is made up of 376 pieces of vinyl-coated aluminium panels, covering a surface of 625 m2. The material achieves 30% reflectivity, ensuring immense clarity.
About 43 million perforations in the screen allow both sound and air-conditioning to pass through to the audience. Stretching 180 degrees horizontal from wall to wall and tilted at a 30-degree angle to the horizon, the screen "wraps" over the audience to cover 80% of a hemisphere so that the images far exceed a person's field of vision. The theatre was originally opened with a seating capacity of 276 and was the first dedicated IMAX Dome/OMNIMAX theatre, and the first overall IMAX installation, in Southeast Asia. A refurbishment in 2015 saw the theatre's seating capacity reduced to 221, and the original IMAX Dome analogue film system was replaced with a new Evans & Sutherland "8K" Digistar 5 digital planetarium theatre system.
References
External links
Science Centre, Singapore
Planetaria
Cinemas in Singapore | Omni-Theatre, Science Centre Singapore | [
"Astronomy"
] | 546 | [
"Astronomy education",
"Astronomy organizations",
"Planetaria"
] |
8,963,881 | https://en.wikipedia.org/wiki/The%20Hitchhiker%27s%20Guide%20to%20the%20Galaxy%20%28fictional%29 | The Hitchhiker's Guide to the Galaxy is a fictional electronic guide book in the multimedia scifi/comedy series of the same name by Douglas Adams. The Guide serves as "the standard repository for all knowledge and wisdom" for many members of the series' galaxy-spanning civilization. Entries from the guidebook are used as comic narration to bridge events and provide background information in every version of the story. The guide is published by "Megadodo Publications", a publishing company on Ursa Minor Beta, and it is written and edited by many characters throughout the series.
In the original radio scripts, the Guide's voice was called the "Narrator" and in the 2004–2005 series, "The Voice". For all of the radio series and the 1981 TV series, the role was credited as "The Book", though this was changed to "Narrator/The Guide" for the 2005 movie.
In the first two phases of the radio series, the LP album adaptations of the first radio series and in the television series, the Guide was voiced by British actor Peter Jones. During the 2004–2005 radio series, The Guide was voiced by William Franklyn. In the film version, it was voiced by Stephen Fry. In the Hexagonal Phase of the radio series, based on the novel, And Another Thing..., the Guide was voiced by the series co-creator John Lloyd.
Overview
The "wholly remarkable" Guide is described as being Megadodo Publications' most successful book, being more popular than The Celestial Homecare Omnibus, better-selling than 53 More Things To Do in Zero Gravity and more controversial than philosophical author Oolon Colluphid's blockbuster "God Trilogy" (Where God Went Wrong, Some More of God's Greatest Mistakes, and Who is this God Person Anyway?).
It is said to have supplanted the rival Encyclopedia Galactica as a "standard repository of all knowledge and wisdom" in some parts of the galaxy for two reasons, one of them being that has a slightly cheaper price, and the other that it has the words "DON'T PANIC" printed on its cover.
Entries
The Guides numerous entries are quoted throughout the various incarnations of the Hitchhiker's Guide series. As well as offering background information, the Guide's entries often employ irony, sarcasm and subtle commentary on the action and on life in general. For instance, the entry on the Sirius Cybernetics Corporation describes their marketing division as "a bunch of mindless jerks who will be the first against the wall when the revolution comes", with a footnote to the effect that the editors would welcome applications from anyone interested in taking over the post of robotics correspondent. The entry on the villainous Vogons begins, "Here's what to do if you want to get a lift from a Vogon: forget it." The entry on "What to do if you find yourself stuck in a crack in the ground underneath a giant boulder you can't move, with no hope of rescue" suggests that first, you "consider how lucky you are that life has been good to you so far. Alternatively, if life hasn't been good to you so far, which given your current circumstances seems more likely, consider how lucky you are that it won't be troubling you much longer." Its advice on drunkenness is simply, "Go to it, and good luck", and according to the 2005 film, its entry on love is "Avoid, if at all possible".
The Guide tends to focus on certain topics. For instance, if looking for information about sex, the Guide suggests reading "chapters seven, nine, ten, eleven, fourteen, sixteen, seventeen, nineteen, twenty-one to eighty-four inclusive, and in fact most of the rest of the Guide." On the Guide'''s outdated and typo-filled entries (some of which could cause serious injury or death, such as "Ravenous Bugblatter Beasts often make a very good meal for visiting tourists," rather than "Ravenous Bugblatter Beasts often make a very good meal of visiting tourists.") Adams wrote, "...though it cannot hope to be useful or informative on all matters, it does make the reassuring claim that where it is inaccurate, it is at least definitively inaccurate. In cases of major discrepancy it was always reality that's got it wrong."
Editing
Despite the work of dedicated field researchers such as Ford Prefect, many of the contributions to the Guide are made on a strictly ad-hoc basis. With the permanent staff more likely to be on a lunch break than working, "most of the actual work got done by any passing stranger who happened to wander into the empty offices of an afternoon and saw something worth doing." This has led to the Guide being patchy in its coverage, cobbled together (for example: the entry on "The Universe" was copied from the back of a packet of breakfast cereal) and often riddled with errors. The novel of the same name notes that "it has many omissions and contains much that is apocryphal, or at least wildly inaccurate ...."
Although Ford puts together a lengthy and detailed entry on Earth during the 15 years he is stranded there, the editors cut it down to two words: "Mostly harmless." In So Long, and Thanks for All the Fish, he is stunned to see his entire original work restored during a database update, even though he saw the planet being demolished by the Vogons. The change turns out to be necessary because another Earth has been pulled into existence from a parallel universe by dolphins in order to prevent humans from becoming extinct.
The Guide can receive updates to its data base via Sub-Etha. Field researchers (like Ford Prefect) can also use the Guide to edit entries and transmit these back to the publisher.
Publisher
At the start of the series, the Guide was published by Megadodo Publications, one of the "great publishing corporations of Ursa Minor." When Megadodo was bought out by Infinidim Enterprises in Mostly Harmless, the new editor in chief, Vann Harl, changed the Guide's demographic from penniless hitchhikers to families in billions of billions of alternate worlds, thus altering the Guide's original purpose. When Ford learned of this plan, he knocked out Vann Harl and stole his Ident-I-Eeze card to increase the spending limit on Ford's own Dine-O-Charge card. Ford was thus able to use his Dine-O-Charge to buy (among other things): a pink spaceship, all the foie gras in London, and The London Zoo, in addition to buying the hotel he was staying at for the concierge, all charged to the Guide and Infinidim Enterprises.
Physical description
In the radio series, Ford describes the Guide as "a sort of electronic book", with several million entries.
In the first book, Ford's copy of the Guide is described as looking "rather like a largish electronic calculator" and "insanely complicated", with "about a hundred tiny flat press buttons and a screen about four inches square" which could display any of a million pages. The Guide reads its entries aloud in a "still quiet measured voice".
In So Long, and Thanks for All the Fish, Arthur's copy is described as resembling "a small, thin, flexible lap computer" encased in a "sturdy plastic cover" with the words "Don't Panic" inscribed on it "in large, friendly letters". Arthur's copy of the Guide is described as "battered and travelworn" by this point in the series, having survived being thrown into a river, "frozen on the glaciers of the moon of Jaglan Beta, sat on, kicked around spaceships, scuffed and generally abused".
The Guide's entries are arranged alphabetically on the screen and accessed via typing entry codes on a keyboard; "Earth" is on the same page as "Eccentrica Gallumbits, the Triple-Breasted Whore of Eroticon 6." In So Long, and Thanks for All the Fish the Guide's "current tally" of pages is said to be 5,975,509.
In the film, the Guide is depicted as a large metal book with a large screen instead of pages. This incarnation's entries are reached by voice activation (in the only example of this being shown, saying the word "Vogon" brought up the article on Vogons.)
Personality
At the start, the Guide is merely an information resource, although one with a distinctly flippant and exuberant tone. Its introduction begins with the words, "Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean you may think it's a long walk down the road to the chemist, but that's just peanuts to space. Listen..." However, in the fifth novel, Mostly Harmless, a new edition of the Guide, the Guide Mark II, is published that is artificially intelligent and capable of interacting with the reader. This Guide, which takes the form of a black, birdlike robot, appears pleasant and friendly but is in fact deeply malevolent and in league with the Vogons in a plot to destroy Earth. Strangely enough, it saves all the main characters from certain doom as part of some unknown agenda and disappears from existence shortly before the Grebulons destroy Earth at the beginning of the sixth book in the series, And Another Thing by Eoin Colfer.
Representation
In the original radio series, Peter Jones provided the voice for "The Book" as both the Guide itself and as the overall narrator. When speaking as the Guide, Jones's voice was electronically filtered to sound mechanical, and spoken against simple electronic music. When speaking merely as the narrator, his voice was left unfiltered.
In the television series, Jones's voice was left unfiltered for both the Guide and "general" narrations, which were accompanied by hand-drawn animations representing computer readouts. These animations often contained little jokes, such as the full text of the "worst poetry in the universe", the equation of 37 Earth miles as "1 Altairian long way", the inclusion of a topping of meringue on a Magrathea-constructed planet, and the outcome of an intergalactic war represented as a video game score.
The 2005 film, which featured Stephen Fry as the narrator/Guide, also employed animations, but in a more minimalist, abstract style. They were animated by Shynola.
An illustrated 42nd anniversary edition of the book featured illustrations by Chris Riddell, often used to accompany Guide entries.
Inspiration
Adams conceived of the Guide while hitchhiking from London to Istanbul in 1971. Drunk and penniless in a field in Innsbruck, Austria, Adams looked up at the stars and then at his stolen copy of Hitch-hiker's Guide to Europe and thought that someone should write The Hitchhiker's Guide to the Galaxy. The Hitch-hiker's Guide to Europe claimed in its introduction that it was possible to survive in Europe on less than US$25 a week, a claim echoed in the catchphrase of the Hitchhiker's Guide to the Galaxy that it was the best source of advice for those who wanted to see the universe "on less than 30 Altairian dollars a day."
In reality
Douglas Adams, who was deeply involved with computer technology, founded the website h2g2 in 1999. In keeping with the Hitchhiker's Guides tradition of being edited by random people off the street, h2g2 is an encyclopedia edited by thousands of contributors. The site's creation predates Wikipedia by two years, though several commentators have noted the similarities between Wikipedia and the Hitchhiker's Guide, particularly its wild variance in reliability and quality and its tendency to focus on topics of interest to its writers.
In 2000 Adams wrote:
Some have compared Apple's iPad and Amazon's Kindle to the Hitchhiker's Guide; indeed fans have designed "Don't Panic" covers for both.
Combining tablets or e-readers with Wikipedia is often considered the closest existing equivalent to the Hitchhiker's Guide to date. An app for the iPad allows users to read Guide entries as they appeared in the various Hitchhikers media.
See also
Encyclopedia Galactica''
References
The Hitchhiker's Guide to the Galaxy
Fictional books
Fictional encyclopedias
Fictional artificial intelligences
Fictional computers
Interstellar communication | The Hitchhiker's Guide to the Galaxy (fictional) | [
"Technology"
] | 2,615 | [
"Fictional computers",
"Computers"
] |
8,963,941 | https://en.wikipedia.org/wiki/Raul%20Proen%C3%A7a | Raul Proença (May 10, 1884 – May 20, 1941) was a Portuguese writer, journalist, and intellectual. Born in Caldas da Rainha, Proença earned a degree in economic and financial sciences from the Instituto Industrial e Comercial de Lisboa. He was a founder of the magazine Seara Nova. In 1927, Proença was exiled to Paris. Proença returned to Portugal in 1932. He was hospitalized for mental illness, but died of typhoid fever in Porto.
Proença was a supporter of Lamarckian evolution. He argued that Jean-Baptiste Lamarck was the true founder of evolution.
Biography
Graduated in Economic and Financial Sciences from the Industrial and Commercial Institute of Lisbon, with multifaceted thinking, he defined himself philosophically as an idealist and realist, defender of democratic socialism within a parliamentary regime.
Raul exiled to Paris, France in 1927 after Portugal was going through a military dictatorship. He defended his ideas and fought against Sidonism and the military dictatorship, which appeared in 1926.He is, nevertheless, a "victim" of the mentality of his time, adhering to racist dogmas, then popular in certain republican circles. He published in this topic, for example, "The Military Dictatorship: History and Analysis of a Crime", in which he defends democracy from men like Mussolini who destroyed it in his country. But he also defends Eugenics, for a "purer race", calling for a "politics of race" that corrects Portuguese decadence, the main cause of which he said was "ethnic degradation" due to "our sensuality" "in contact with other peoples." He therefore declared a "physiological policy" the most important of policies, "defending the Portuguese from greater bastardizations", seeking an "unharmed" race, along with national re-education. He would also declare, contradicting the dogmas of the time, the " intellectual superiority of Portuguese women over men", even though he declared this as an "extraordinary" symptom of an "ethnic and educational catastrophe".
References
External links
Raul Proença — profile from Centro Virtual Camões
Ecsola Secundária Raul Proença — secondary school in Caldas da Rainha, Portugal
1884 births
1941 deaths
Deaths from typhoid fever
Infectious disease deaths in Portugal
Lamarckism
Portuguese male journalists
Portuguese male writers
20th-century Portuguese journalists
People from Caldas da Rainha | Raul Proença | [
"Biology"
] | 500 | [
"Non-Darwinian evolution",
"Biology theories",
"Obsolete biology theories",
"Lamarckism"
] |
14,776,532 | https://en.wikipedia.org/wiki/HIST1H2AE | Histone H2A type 1-B/E is a protein that in humans is encoded by the HIST1H2AE gene.
Histones are basic nuclear proteins that are responsible for the nucleosome structure of the chromosomal fiber in eukaryotes. Nucleosomes consist of approximately 146 bp of DNA wrapped around a histone octamer composed of pairs of each of the four core histones (H2A, H2B, H3, and H4).
The chromatin fiber is further compacted through the interaction of a linker histone, H1, with the DNA between the nucleosomes to form higher order chromatin structures. This gene is intronless and encodes a member of the histone H2A family. Transcripts from this gene lack polyA tails; instead, they contain a palindromic termination element. This gene is found in the large histone gene cluster on chromosome 6p22-p21.3.
References
Further reading | HIST1H2AE | [
"Chemistry"
] | 213 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,776,609 | https://en.wikipedia.org/wiki/HOXB1 | Homeobox protein Hox-B1 is a protein that in humans is encoded by the HOXB1 gene.
Function
This gene belongs to the homeobox family of genes. The homeobox genes encode a highly conserved family of transcription factors that play an important role in morphogenesis in all multicellular organisms. Mammals possess four similar homeobox gene clusters, HOXA, HOXB, HOXC and HOXD, located on different chromosomes, consisting of 9 to 11 genes arranged in tandem. This gene is one of several homeobox HOXB genes located in a cluster on chromosome 17.
Interactions
HOXB1 has been shown to interact with PBX1.
See also
Tandemly arrayed genes
References
Further reading
External links
Transcription factors | HOXB1 | [
"Chemistry",
"Biology"
] | 160 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,622 | https://en.wikipedia.org/wiki/HOXB2 | Homeobox protein Hox-B2 is a protein that in humans is encoded by the HOXB2 gene.
Function
This gene is a member of the Antp homeobox family and encodes a nuclear protein with a homeobox DNA-binding domain. It is included in a cluster of homeobox B genes located on chromosome 17. The encoded protein functions as a sequence-specific transcription factor that is involved in development. Increased expression of this gene is associated with pancreatic cancer.
See also
Homeobox
References
Further reading
External links
Transcription factors | HOXB2 | [
"Chemistry",
"Biology"
] | 116 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,684 | https://en.wikipedia.org/wiki/KIF4A | Kinesin family member 4A is a protein that in humans is encoded by the KIF4A gene.
Function
Kinesins, such as KIF4A, are microtubule-based motor proteins that generate directional movement along microtubules. They are involved in many crucial cellular processes, including cell division.
Interactions
KIF4A has been shown to interact with HMG20B and DNMT3B.
Clinical significance
NTCP is the entry receptor for both Hepatitis B (HBV) and Hepatitis D viruses (HDV). KIF4 was found to play an essential role in HBV and HDV infection through its regulation of the retrograde transport of NTCP from the cytoplasm to the cell surface where it acts as a receptor for HBV/HDV infection.
References
Further reading
External links
Human proteins
Motor proteins | KIF4A | [
"Chemistry"
] | 177 | [
"Molecular machines",
"Motor proteins"
] |
14,776,763 | https://en.wikipedia.org/wiki/UHRF1 | Ubiquitin-like, containing PHD and RING finger domains, 1, also known as UHRF1, is a protein which in humans is encoded by the UHRF1 gene.
Function
This gene encodes a member of a subfamily of RING-finger type E3 ubiquitin ligases. The protein binds to hemi-methylated DNA during S-phase and recruits the main DNA methyltransferase protein, DNMT1, to regulate chromatin structure and gene expression. Its expression peaks at late G1 phase and continues during G2 and M phases of the cell cycle. It plays a major role in the G1/S transition, and functions in the p53-dependent DNA damage checkpoint. Multiple transcript variants encoding different isoforms have been found for this gene. It was originally identified as a direct regulator of topoisomerase 2a, but this has subsequently been disproven. Uhrf1 has been extensively studied in vivo using zebrafish.
Clinical significance
UHRF1 has recently been identified as a novel oncogene in hepatocellular carcinoma, the primary type of liver cancer.
References
Further reading | UHRF1 | [
"Chemistry"
] | 238 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,776,851 | https://en.wikipedia.org/wiki/HOXB9 | Homeobox protein Hox-B9 is a protein that in humans is encoded by the HOXB9 gene.
Function
This gene is a member of the Abd-B homeobox family and encodes a protein with a homeobox DNA-binding domain. It is included in a cluster of homeobox B genes located on chromosome 17. The encoded nuclear protein functions as a sequence-specific transcription factor that is involved in cell proliferation and differentiation. Increased expression of this gene is associated with some cases of leukemia, prostate cancer and lung cancer.
Interactions
HOXB9 has been shown to interact with BTG2 and BTG1.
See also
Homeobox
References
Further reading
External links
Transcription factors | HOXB9 | [
"Chemistry",
"Biology"
] | 145 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,879 | https://en.wikipedia.org/wiki/HOXD3 | Homeobox protein Hox-D3 is a protein that in humans is encoded by the HOXD3 gene.
Function
This gene belongs to the homeobox family of genes. The homeobox genes encode a highly conserved family of transcription factors that play an important role in morphogenesis in all multicellular organisms. Mammals possess four similar homeobox gene clusters, HOXA, HOXB, HOXC and HOXD, located on different chromosomes, consisting of 9 to 11 genes arranged in tandem. This gene is one of several homeobox HOXD genes located at 2q31-2q37 chromosome regions. Deletions that removed the entire HOXD gene cluster or 5' end of this cluster have been associated with severe limb and genital abnormalities. The protein encoded by this gene may play a role in the regulation of cell adhesion processes.
See also
Homeobox
References
Further reading
External links
Transcription factors | HOXD3 | [
"Chemistry",
"Biology"
] | 196 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,902 | https://en.wikipedia.org/wiki/HSF2 | Heat shock factor protein 2 is a protein that in humans is encoded by the HSF2 gene.
Function
HSF2, as well as the related gene HSF1, encodes a protein that binds specifically to the heat-shock element and has homology to HSFs of other species. Heat shock transcription factors activate heat-shock response genes under conditions of heat or other stresses. Although the names HSF1 and HSF2 were chosen for historical reasons, these peptides should be referred to as heat-shock transcription factors.
Interactions
HSF2 has been shown to interact with Nucleoporin 62 and HSF1.
See also
Heat shock factor
References
Further reading
External links
Transcription factors | HSF2 | [
"Chemistry",
"Biology"
] | 141 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,917 | https://en.wikipedia.org/wiki/IRF8 | Interferon regulatory factor 8 (IRF8) also known as interferon consensus sequence-binding protein (ICSBP), is a protein that in humans is encoded by the IRF8 gene. IRF8 is a transcription factor that plays critical roles in the regulation of lineage commitment and in myeloid cell maturation including the decision for a common myeloid progenitor (CMP) to differentiate into a monocyte precursor cell.
Function
Interferon Consensus Sequence-binding protein (ICSBP) is a transcription factor of the interferon regulatory factor (IRF) family. Proteins of this family are composed of a conserved DNA-binding domain in the N-terminal region and a divergent C-terminal region that serves as the regulatory domain. The IRF family proteins bind to the IFN-stimulated response element (ISRE) and regulate expression of genes stimulated by type I IFNs, namely IFN-α and IFN-β. IRF family proteins also control expression of IFN-α and IFN-β-regulated genes that are induced by viral infection.
Knockout studies
IFN-producing cells (mIPCs) were absent in all lymphoid organs from ICSBP knockout (KO) mice, as revealed by lack of CD11clowB220+Ly6C+CD11b− cells. In parallel, CD11c+ cells isolated from ICSBP KO spleens were unable to produce type I IFNs in response to viral stimulation. ICSBP KO mice also displayed a marked reduction of the DC subset expressing the CD8alpha marker (CD8alpha+ DCs) in spleen, lymph nodes, and thymus. Moreover, ICSBP-deficient CD8alpha+ DCs exhibited a markedly impaired phenotype when compared with WT DCs. They expressed very low levels of costimulatory molecules (intercellular adhesion molecule ICAM1, CD40, CD80, CD86) and of the T cell area-homing chemokine receptor CCR7.
Clinical significance
In myeloid cells, IRF8 regulates the expression of Bax and Fas to regulate apoptosis. In chronic myelogenous leukemia (CML), IRF8 regulates acid ceramidase to mediate CML apoptosis.
IRF8 is highly expressed in myeloid cells and was originally identified in as a critical lineage-specific transcription factor for myeloid cell differentiation, recent studies, however, have shown that IRF8 is also constitutively expressed in non-hematopoietic cancer cells, albeit at a lower level. Furthermore, IRF8 can also be up-regulated by IFN-γ in non-hemotopoietic cells. IRF8 mediates the expression of Fas, Bax, FLIP, Jak1 and STAT1 to mediate apoptosis in non-hemotopoietic cancer cells.
Analysis of human cancer genomics database revealed that IRF8 is not significantly focally amplified across the entire dataset of 3131 tumors, but is significantly focally deleted across the entire dataset of 3131 tumors, suggesting that IRF8 is potentially a tumor suppressor in humans. Molecular analysis indicated that the IRF8 gene promoter is hypermethylated in human colon carcinoma cells, suggesting that these cells might use DNA methylation to silence IRF8 expression to advance the disease.
Interactions
IRF8 has been shown to interact with IRF1 and COPS2.
See also
Interferon regulatory factors
References
Illustrations
Further reading
External links
Transcription factors | IRF8 | [
"Chemistry",
"Biology"
] | 756 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,776,926 | https://en.wikipedia.org/wiki/IGHG1 | Ig gamma-1 chain C region is a protein that in humans is encoded by the IGHG1 gene.
References
Further reading | IGHG1 | [
"Chemistry"
] | 29 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,776,965 | https://en.wikipedia.org/wiki/International%20Association%20of%20Online%20Engineering | The International Association of Online Engineering (IAOE) is an international non-profit organization with the objective of encouraging the wider development, distribution and application of Online Engineering (OE) technologies and its influence to the society. The association seeks to foster practices in education and research in universities, higher education institutions and the industry on OE. Moreover, the IAOE promotes OE for the improvement of living and working conditions. The IAOE encourages the exchange of knowledge as well as the exchange of staff and students between co-operating institutions.
Aim and Vision
IAOE proclaims a growing complexity of engineering tasks, increasingly specialized and expensive equipment as well as software tools and simulators. It also observes the necessary use of expensive equipment and software tools/simulators in short time projects. As a consequence, it is increasingly necessary to allow and organize a shared use of equipment, but also specialized software as for example simulators.
Aims of the association in general are:
to bundle the activities of the already existing community in the field of Online Engineering,
spreading of up to date information and knowledge in the field of Online Engineering,
organizing conferences and publications,
provision of different services for the members,
supporting the development of OE in developing countries.
This includes the promotion of:
the subject "Online Engineering" at universities and other educational institutions,
the application of Online Engineering in small and medium enterprises (SMEs),
the information about Online Engineering solutions especially in the developing countries and for people with special demands,
networking of the knowhow of the members,
international projects between the members especially between the universities and the industry,
quality assurance of Online Engineering in education and further education programs,
exchange of scientists and students.
Publications
The International Journal of Online Engineering is the official publication of IAOE.
It is published quarterly. The association furthermore supports the International Journal of Emerging Technologies in Learning (iJET) and the International Journal of Interactive Mobile Technologies (iJIM). IAOE also runs the scientific journal hosting platform Online-Journals.org, thus aiming at contributing to the advancement of science by providing an efficient and cost-effective way for making qualitative scientific results easily accessible to the largest possible audience.
Conferences
The annual conference of the International Association of Online Engineering is the International Conference on Remote Engineering and Virtual Instrumentation (REV). Furthermore, IAOE is organizer or co-organizer of the following conferences:
International Conference on Interactive Computer aided Learning (ICL), Conference on Interactive Mobile and Computer aided Learning (IMCL), Conference on Interactive Computer aided Blended Learning (ICBL).
See also
Electronics
Online Engineering
Virtual instrumentation
References
Organizations established in 2006
International professional associations
Engineering organizations
International organisations based in Austria | International Association of Online Engineering | [
"Engineering"
] | 537 | [
"nan"
] |
14,776,980 | https://en.wikipedia.org/wiki/ILF2 | Interleukin enhancer-binding factor 2 is a protein that in humans is encoded by the ILF2 gene.
Function
Nuclear factor of activated T-cells (NFAT) is a transcription factor required for T-cell expression of the interleukin 2 gene. NFAT binds to a sequence in the interleukin 2 gene enhancer known as the antigen receptor response element 2. In addition, NFAT can bind RNA and is an essential component for encapsidation and protein priming of hepatitis B viral polymerase. NFAT is a heterodimer of 45 kDa and 90 kDa proteins, the smaller of which is the product of this gene. The encoded protein binds strongly to the 90 kDa protein and stimulates its ability to enhance gene expression.
Interactions
ILF2 has been shown to interact with CDC5L and DNA-PKcs.
ILF2 and ILF3 have been identified as autoantigens in mice with induced lupus, in canine systemic rheumatic autoimmune disease, and as a rare finding in humans with autoimmune disease.
References
Further reading
External links
PDBe-KB provides an overview of all the structure information available in the PDB for Mouse Interleukin enhancer-binding factor 2 (ILF2)
Transcription factors | ILF2 | [
"Chemistry",
"Biology"
] | 271 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,007 | https://en.wikipedia.org/wiki/KCNJ12 | ATP-sensitive inward rectifier potassium channel 12 is a lipid-gated ion channel that in humans is encoded by the KCNJ12 gene.
Function
This gene encodes an inwardly rectifying K+ channel that may be blocked by divalent cations. This protein is thought to be one of multiple inwardly rectifying channels that contribute to the cardiac inward rectifier current (IK1). The gene is located within the Smith–Magenis syndrome region on chromosome 17.
Interactions
KCNJ12 has been shown to interact with:
APBA1,
CASK,
DLG1,
DLG2,
DLG3,
DLG4,
LIN7A
LIN7B, and
LIN7C.
See also
Inward-rectifier potassium channel
References
Further reading
External links
Ion channels | KCNJ12 | [
"Chemistry"
] | 168 | [
"Neurochemistry",
"Ion channels"
] |
14,777,101 | https://en.wikipedia.org/wiki/LIMS1 | LIM and senescent cell antigen-like-containing domain protein 1 is a protein that in humans is encoded by the LIMS1 gene.
Function
The protein encoded by this gene is an adaptor protein which contains five LIM domains, or double zinc fingers. The protein is likely involved in integrin signaling through its LIM domain-mediated interaction with integrin-linked kinase, found in focal adhesion plaques. It is also thought to act as a bridge linking integrin-linked kinase to NCK adaptor protein 2, which is involved in growth factor receptor kinase signaling pathways. Its localization to the periphery of spreading cells also suggests that this protein may play a role in integrin-mediated cell adhesion or spreading.
Interactions
LIMS1 has been shown to interact with Integrin-linked kinase and NCK2.
References
Further reading | LIMS1 | [
"Chemistry"
] | 175 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,131 | https://en.wikipedia.org/wiki/Basal%20cell%20adhesion%20molecule | Basal cell adhesion molecule, also known as Lutheran antigen, is a plasma membrane glycoprotein that in humans is encoded by the BCAM gene. BCAM has also recently been designated CD239 (cluster of differentiation 239).
Function
Lutheran blood group glycoprotein is a member of the immunoglobulin superfamily and a receptor for the extracellular matrix protein, laminin. The protein contains five, N-terminus, extracellular immunoglobulin domains, a single transmembrane domain, and a short, C-terminal cytoplasmic tail. This protein may play a role in epithelial cell cancer and in vaso-occlusion of red blood cells in sickle cell disease. Two transcript variants encoding different isoforms have been found for this gene.
Interactions
BCAM has been shown to interact with Laminin, alpha 5. BCAM has also been shown to promote the metastasis of ovarian cancer.
References
Further reading
External links
Clusters of differentiation
Immunoglobulin superfamily
Glycoproteins | Basal cell adhesion molecule | [
"Chemistry"
] | 225 | [
"Glycoproteins",
"Glycobiology"
] |
14,777,257 | https://en.wikipedia.org/wiki/NFE2 |
Transcription factor NF-E2 45 kDa subunit is a protein that in humans is encoded by the NFE2 gene.
It is involved in megakaryocyte production.
Interactions
NFE2 has been shown to interact with CREB-binding protein.
References
Further reading
External links
Transcription factors
Human proteins | NFE2 | [
"Chemistry",
"Biology"
] | 64 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,346 | https://en.wikipedia.org/wiki/NFYC | Nuclear transcription factor Y subunit gamma is a protein that in humans is encoded by the NFYC gene.
Function
The protein encoded by this gene is one subunit of a trimeric complex, forming a highly conserved transcription factor that binds with high specificity to CCAAT motifs in the promoter regions in a variety of genes. This gene product, subunit C, forms a tight dimer with the B subunit (NFYB), a prerequisite for subunit A (NFYA) association. The resulting trimer binds to DNA with high specificity and affinity. Subunits B and C each contain a histone-like motif. Observation of the histone nature of these subunits is supported by two types of evidence; protein sequence alignments and experiments with mutants. Additional regulation, preliminarily supported by the EST database, may be represented by alternative splicing in this subunit.
Two microRNAs; miR-30c and miR-30e are located within introns of the nfyc gene. These microRNAs are actively transcribed in human insulin-producing beta cells in the pancreatic islets that also show high expression of nfyc and CDH1 genes. The expression of these intronic microRNAs is essential for maintaining the differentiated phenotype of human islet beta cells. Inhibition of miR-30 family microRNAs induces epithelial-mesenchymal transition of human pancreatic islet cells.
Interactions
NFYC has been shown to interact with Myc.
References
Further reading
External links
Transcription factors | NFYC | [
"Chemistry",
"Biology"
] | 318 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,367 | https://en.wikipedia.org/wiki/NRL%20%28gene%29 | Neural retina-specific leucine zipper protein is a protein that in humans is encoded by the NRL gene.
Function
This gene encodes a basic motif-leucine zipper transcription factor of the Maf subfamily. The encoded protein is conserved among vertebrates and is a critical intrinsic regulator of photoreceptor cell development and function. Mutations in this gene have been associated with retinitis pigmentosa and degenerative diseases of the retina.
See also
Transcription factor
References
Further reading
External links
GeneReviews/NCBI/NIH/UW entry on Retinitis Pigmentosa Overview
Transcription factors | NRL (gene) | [
"Chemistry",
"Biology"
] | 127 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,398 | https://en.wikipedia.org/wiki/Plakophilin-1 | Plakophilin-1 is a protein that in humans is encoded by the PKP1 gene.
Function
This gene encodes a member of the arm-repeat (armadillo) and plakophilin gene families. Plakophilin proteins contain numerous armadillo repeats, localize to cell desmosomes and nuclei, and participate in linking cadherins to intermediate filaments in the cytoskeleton. This protein may be involved in molecular recruitment and stabilization during desmosome formation. Mutations in this gene have been associated with the ectodermal dysplasia/skin fragility syndrome.
Interactions
PKP1 has been shown to interact with Desmoplakin.
See also
Skin fragility syndrome
References
Further reading
Armadillo-repeat-containing proteins | Plakophilin-1 | [
"Chemistry"
] | 167 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,406 | https://en.wikipedia.org/wiki/PLAG1 | Zinc finger protein PLAG1 is a protein that in humans is encoded by the PLAG1 gene.
Function
Pleomorphic adenoma gene 1 encodes a zinc finger protein with 2 putative nuclear localization signals. PLAG1, which is developmentally regulated, has been shown to be consistently rearranged in pleomorphic adenomas of the salivary glands. PLAG1 is activated by the reciprocal chromosomal translocations involving 8q12 in a subset of salivary gland pleomorphic adenomas.
Interactions
PLAG1 has been shown to interact with Karyopherin alpha 2.
References
Further reading
External links
Transcription factors | PLAG1 | [
"Chemistry",
"Biology"
] | 136 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,439 | https://en.wikipedia.org/wiki/PRKAR1B | cAMP-dependent protein kinase type I-beta regulatory subunit is an enzyme that in humans is encoded by the PRKAR1B gene.
Clinical significance
Mutations in PRKAR1B cause neurodegenerative disorder.
Interactions
PRKAR1B has been shown to interact with AKAP1 and PRKAR1A.
References
Further reading
External links
Genes on human chromosome 7 | PRKAR1B | [
"Chemistry"
] | 75 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,567 | https://en.wikipedia.org/wiki/Ethenone | Ethenone is the formal name for ketene, an organic compound with formula or . It is the simplest member of the ketene class. It is an important reagent for acetylations.
Properties
Ethenone is a highly reactive gas (at standard conditions) and has a sharp irritating odour. It is only reasonably stable at low temperatures (−80 °C). It must therefore always be prepared for each use and processed immediately, otherwise a dimerization to diketene occurs or it reacts to polymers that are difficult to handle. The polymer content formed during the preparation is reduced, for example, by adding sulfur dioxide to the ketene gas. Because of its cumulative double bonds, ethenone is highly reactive and reacts in an addition reaction H-acidic compounds to the corresponding acetic acid derivatives. It does for example react with water to acetic acid or with primary or secondary amines to the corresponding acetamides.
Preparation
Ethenone is produced by thermal dehydration of acetic acid at 700–750 °C in the presence of triethyl phosphate as a catalyst:
It has also been produced on a laboratory scale by the thermolysis of acetone at .
This reaction is called the Schmidlin ketene synthesis.
On a laboratory scale it can be produced by the thermal decomposition of Meldrum's acid at temperatures greater than 200 °C.
History
Ethenone was first produced in 1907 by N. T. M. Wilsmore through pyrolysis of acetone or acetic anhydride vapours over a hot platinum wire in an apparatus that was later developed by Charles D. Hurd into the "Hurd lamp" or "ketene lamp". This apparatus consists of a heated flask of acetone producing vapours which are pyrolyzed by a metal filament electrically heated to red heat, with a condenser to return unreacted acetone to the boiling flask. Other heating methods have been used and similar methods were used on a larger scale for the industrial production of ketene for acetic anhydride synthesis.
Ethenone was discovered at the same time by Hermann Staudinger (by reaction of bromoacetyl bromide with metallic zinc) The dehydration of acetic acid was reported in 1910.
The thermal decomposition of acetic anhydride was also described.
Natural occurrence
Ethenone has been observed to occur in space, in comets or in gas as part of the interstellar medium.
Use
Ethenone is used to make acetic anhydride from acetic acid. Generally it is used for the acetylation of chemical compounds.
Ethenone reacts with methanal in the presence of catalysts such as Lewis acids (AlCl3, ZnCl2 or BF3) to give β-propiolactone. The technically most significant use of ethenone is the synthesis of sorbic acid by reaction with 2-butenal (crotonaldehyde) in toluene at about 50 °C in the presence of zinc salts of long-chain carboxylic acids. This produces a polyester of 3-hydroxy-4-hexenoic acid, which is thermally or hydrolytically depolymerized to sorbic acid.
Ethenone is very reactive, tending to react with nucleophiles to form an acetyl group. For example, it reacts with water to form acetic acid; with acetic acid to form acetic anhydride; with ammonia and amines to form ethanamides; and with dry hydrogen halides to form acetyl halides.
The formation of acetic acid likely occurs by an initial formation of 1,1-dihydroxyethene, which then tautomerizes to give the final product.
Ethenone will also react with itself via [2 + 2] photocycloadditions to form cyclic dimers known as diketenes. For this reason, it should not be stored for long periods.
Hazards
Exposure to concentrated levels causes humans to experience irritation of body parts such as the eye, nose, throat and lungs. Extended toxicity testing on mice, rats, guinea pigs and rabbits showed that ten-minute exposures to concentrations of freshly generated ethenone as low as 0.2 mg/liter (116 ppm) may produce a high percentage of deaths in small animals. These findings show ethenone is toxicologically identical to phosgene.
The formation of ketene in the pyrolysis of vitamin E acetate, an additive of some e-liquid products, is one possible mechanism of the reported pulmonary damage caused by electronic cigarette use.
A number of patents describe the catalytic formation of ketene from carboxylic acids and acetates, using a variety of metals or ceramics, some of which are known to occur in e-cigarette devices from patients with e-cigarette or vaping product-use associated lung injury (EVALI).
Occupational exposure limits are set at 0.5 ppm (0.9 mg/m3) over an eight-hour time-weighted average.
An IDLH limit is set at 5 ppm, as this is the lowest concentration productive of a clinically relevant physiologic response in humans.
References
Literature
Tidwell, Thomas T. Ketenes, 2nd edition. John Wiley & Sons, 2006, .
External links
Ketenes
Gases
Pulmonary agents
Acetylating agents | Ethenone | [
"Physics",
"Chemistry"
] | 1,144 | [
"Matter",
"Chemical weapons",
"Phases of matter",
"Functional groups",
"Pulmonary agents",
"Ketenes",
"Acetylating agents",
"Reagents for organic chemistry",
"Statistical mechanics",
"Gases"
] |
14,777,577 | https://en.wikipedia.org/wiki/UGT1A3 | UDP-glucuronosyltransferase 1-3 is an enzyme that in humans is encoded by the UGT1A3 gene.
This gene encodes a UDP-glucuronosyltransferase, an enzyme of the glucuronidation pathway that transforms small lipophilic molecules, such as steroids, bilirubin, hormones, and drugs, into water-soluble, excretable metabolites. This gene is part of a complex locus that encodes several UDP-glucuronosyltransferases. The locus includes thirteen unique alternate first exons followed by four common exons. Four of the alternate first exons are considered pseudogenes. Each of the remaining nine 5' exons may be spliced to the four common exons, resulting in nine proteins with different N-termini and identical C-termini. Each first exon encodes the substrate binding site, and is regulated by its own promoter. Substrates of this enzyme include estrone, 2-hydroxyestrone, and metabolites of benzo(a)pyrene.
References
Further reading | UGT1A3 | [
"Chemistry"
] | 245 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,608 | https://en.wikipedia.org/wiki/International%20Conference%20on%20Remote%20Engineering%20and%20Virtual%20Instrumentation | International Conference on Remote Engineering and Virtual Instrumentation (REV) is an annual IAOE conference.
REV is an annual conference covering topics on online & remote engineering, virtual instrumentation and applications. Like other conferences, REV offers various tracks and simultaneous sessions, tutorials and workshops.
The first REV was held in Villach, Austria in 2004. It operates under the auspices of the International Association of Online Engineering (IAOE).
REV’s venue changes every year, and the categories of its program vary. Historically REV has combined the presentation of academic papers with comparatively practical experience reports, panels, workshops and tutorials.
Locations and organizers
External links
Official website
Computer science conferences | International Conference on Remote Engineering and Virtual Instrumentation | [
"Technology"
] | 133 | [
"Computer science",
"Computer science conferences"
] |
14,777,618 | https://en.wikipedia.org/wiki/ARID1B | AT-rich interactive domain-containing protein 1B is a protein that in humans is encoded by the ARID1B gene. ARID1B is a component of the human SWI/SNF chromatin remodeling complex.
Clinical significance
Germline mutations in ARID1B are associated with Coffin–Siris syndrome. Somatic mutations in ARID1B are associated with several cancer subtypes, suggesting that it is a tumor suppressor gene.
Interactions
ARID1B has been shown to interact with SMARCA4 and SMARCA2.
References
Further reading
External links
Transcription factors | ARID1B | [
"Chemistry",
"Biology"
] | 122 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,654 | https://en.wikipedia.org/wiki/Coherent%20ring | In mathematics, a (left) coherent ring is a ring in which every finitely generated left ideal is finitely presented.
Many theorems about finitely generated modules over Noetherian rings can be extended to finitely presented modules over coherent rings.
Every left Noetherian ring is left coherent. The ring of polynomials in an infinite number of variables over a left Noetherian ring is an example of a left coherent ring that is not left Noetherian.
A ring is left coherent if and only if every direct product of flat right modules is flat , . Compare this to: A ring is left Noetherian if and only if every direct sum of injective left modules is injective.
References
Ring theory | Coherent ring | [
"Mathematics"
] | 147 | [
"Fields of abstract algebra",
"Ring theory"
] |
14,777,697 | https://en.wikipedia.org/wiki/HCN2 | Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated ion channel 2 is a protein that in humans is encoded by the HCN2 gene.
Interactions
HCN2 has been shown to interact with HCN1 and HCN4.
Function
The function of the channel is not known although its activation by hyperpolarization alludes to the funny channels in the sinoatrial node of the heart (which form the basis of spontaneous generation of electrical rhythm). These channels have recently been associated with chronic pain and blocking the gene is associated with resolution of neuropathic episodes of pain.
See also
Cyclic nucleotide-gated ion channel
References
Further reading
External links
Ion channels | HCN2 | [
"Chemistry"
] | 142 | [
"Neurochemistry",
"Ion channels"
] |
14,777,713 | https://en.wikipedia.org/wiki/KDM5A | Lysine-specific demethylase 5A is an enzyme that in humans is encoded by the KDM5A gene.
Function
The protein encoded by this gene is a ubiquitously expressed nuclear protein. It binds directly, with several other proteins, to retinoblastoma protein which regulates cell proliferation. It was formerly known as Retinoblastoma Binding Protein 2 (RBP2). This protein also interacts with rhombotin-2 which functions distinctly in erythropoiesis and in T-cell leukemogenesis. Rhombotin-2 is thought to either directly affect the activity of the encoded protein or may indirectly modulate the functions of the retinoblastoma protein by binding to this protein. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene.
The Drosophila homolog, LID, was found to be an H3K4 histone demethylase that binds to c-Myc. It was recently renamed to Lysine Demethylase 5 (KDM5).
Enzymatically can be designated as a trimethyllysine dioxygenase, which is a member of the alpha-ketoglutarate-dependent hydroxylase superfamily ().
Interactions
JARID1A has been shown to interact with Estrogen receptor alpha, LMO2 and Retinoblastoma protein.
JARID1A is a major component of the circadian clock, the upregulation of which at the end of the sleep phase blocks HDAC1 activity. Blocking HDAC1 activity results in an upregulation of CLOCK and BMAL1 and consequent upregulation of PER proteins. The PSF (polypyrimidine tract-binding protein-associated splicing factor) within the PER complex recruits SIN3A, a scaffold for assembly of transcriptional inhibitory complexes and rhythmically delivers histone deacetylases to the Per1 promoter, which repress Per1 transcription.
Knockdown of JARID1A promoted osteogenic differentiation of human adipose-derived stromal cells in vitro and in vivo and resulted in marked increases of mRNA expression of osteogenesis-associated genes such as alkaline phosphatase (ALP), osteocalcin (OC), and osterix (OSX). RBP2 was shown to occupy the promoters of OSX and OC to maintain the level of the H3K4me3 mark by chromatin immunoprecipitation assays. RBP2 was also physically and functionally associated with RUNX2, an essential transcription factor that governed osteoblastic differentiation. RUNX2 knockdown impaired the repressive activity of RBP2 in osteogenic differentiation of human adipose-derived stromal cells.
References
Further reading
External links
Transcription factors
Human 2OG oxygenases
EC 1.14.11 | KDM5A | [
"Chemistry",
"Biology"
] | 616 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,734 | https://en.wikipedia.org/wiki/RING1 | E3 ubiquitin-protein ligase RING1 is an enzyme that in humans is encoded by the RING1 gene.
Function
This gene belongs to the RING finger family, members of which encode proteins characterized by a RING domain, a zinc-binding motif related to the zinc finger domain. The gene product can bind DNA and can act as a transcriptional repressor. It is associated with the multimeric polycomb group protein complex. The gene product interacts with the polycomb group proteins BMI1, EDR1, and CBX4, and colocalizes with these proteins in large nuclear domains. It interacts with the CBX4 protein via its glycine-rich C-terminal domain. The gene maps to the HLA class II region, where it is contiguous with the RING finger genes FABGL and HKE4.
Interactions
RING1 has been shown to interact with CBX8, BMI1 and RYBP.
References
Further reading
External links
Transcription factors | RING1 | [
"Chemistry",
"Biology"
] | 206 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,740 | https://en.wikipedia.org/wiki/ROBO1 | Roundabout homolog 1 is a protein that in humans is encoded by the ROBO1 gene.
Function
Bilateral symmetric nervous systems have special midline structures that establish a partition between the two mirror image halves. Some axons project toward and across the midline in response to long-range chemoattractants emanating from the midline. The protein encoded by ROBO1 is structurally similar to a Drosophila integral membrane protein which is encoded by the Drosophila roundabout gene (a member of the immunoglobulin gene superfamily) and is both an axon guidance receptor and a cell adhesion receptor, known to be involved in the decision by axons to cross the central nervous system midline. Two transcript variants encoding different isoforms have been found for ROBO1.
Clinical significance
ROBO1 was implicated in a communication disorder based on a Finnish pedigree with severe dyslexia. Analyses revealed a translocation had occurred disrupting ROBO1. Study of the phonological memory component of the language acquisition system suggests that ROBO1 polymorphisms are associated with functioning in this system. The gene is thought to be related to the brain's ability to represent quantities, and is correlated with better math scores of young children in one limited study.
References
Further reading | ROBO1 | [
"Chemistry"
] | 266 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,746 | https://en.wikipedia.org/wiki/60S%20ribosomal%20protein%20L3 | 60S ribosomal protein L3 is a protein that in humans is encoded by the RPL3 gene.
Function
Ribosomes, the complexes that catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit. Together these subunits are composed of 4 RNA species and approximately 80 structurally distinct proteins. The RPL3 gene encodes a ribosomal protein that is a component of the 60S subunit. The protein belongs to the L3P family of ribosomal proteins and it is located in the cytoplasm. The protein can bind to the HIV-1 TAR mRNA, and it has been suggested that the protein contributes to tat-mediated transactivation. This gene is co-transcribed with several small nucleolar RNA genes, which are located in several of this gene's introns. Alternate transcriptional splice variants, encoding different isoforms, have been characterized. As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of this gene dispersed through the genome.
References
Further reading
Ribosomal proteins | 60S ribosomal protein L3 | [
"Chemistry"
] | 216 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,751 | https://en.wikipedia.org/wiki/60S%20acidic%20ribosomal%20protein%20P1 | 60S acidic ribosomal protein P1 is a protein that in humans is encoded by the RPLP1 gene.
Function
Ribosomes, the organelles that catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit. Together these subunits are composed of 4 RNA species and approximately 80 structurally distinct proteins. This gene encodes a ribosomal phosphoprotein that is a component of the 60S subunit. The protein, which is a functional equivalent of the Escherichia coli L7/L12 ribosomal protein, belongs to the L12P family of ribosomal proteins. It plays an important role in the elongation step of protein synthesis. Unlike most ribosomal proteins, which are basic, the encoded protein is acidic. Its C-terminal end is nearly identical to the C-terminal ends of the ribosomal phosphoproteins P0 and P2. The P1 protein can interact with P0 and P2 to form a pentameric complex consisting of P1 and P2 dimers, and a P0 monomer. The protein is located in the cytoplasm. Two alternatively spliced transcript variants that encode different proteins have been observed. As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of this gene dispersed through the genome.
Interactions
RPLP1 has been shown to interact with RPLP2.
References
Further reading
External links
Ribosomal proteins | 60S acidic ribosomal protein P1 | [
"Chemistry"
] | 302 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,777,789 | https://en.wikipedia.org/wiki/Coxeter%E2%80%93Todd%20lattice | In mathematics, the Coxeter–Todd lattice K12, discovered by , is a 12-dimensional even integral lattice of discriminant 36 with no norm-2 vectors. It is the sublattice of the Leech lattice fixed by a certain automorphism of order 3, and is analogous to the Barnes–Wall lattice. The automorphism group of the Coxeter–Todd lattice has order 210·37·5·7=78382080, and there are 756 vectors in this lattice of norm 4 (the shortest nonzero vectors in this lattice).
Properties
The Coxeter–Todd lattice can be made into a 6-dimensional lattice self dual over the Eisenstein integers. The automorphism group of this complex lattice has index 2 in the full automorphism group of the Coxeter–Todd lattice and is a complex reflection group (number 34 on the list) with structure 6.PSU4(F3).2, called the Mitchell group.
The genus of the Coxeter–Todd lattice was described by and has 10 isometry classes: all of them other than the Coxeter–Todd lattice have a root system of maximal rank 12.
Construction
Based on Nebe web page we can define K12 using following 6 vectors in 6-dimensional complex coordinates. ω is complex number of order 3 i.e. ω3=1.
(1,0,0,0,0,0), (0,1,0,0,0,0), (0,0,1,0,0,0),
½(1,ω,ω,1,0,0), ½(ω,1,ω,0,1,0), ½(ω,ω,1,0,0,1),
By adding vectors having scalar product -½ and multiplying by ω we can obtain all lattice vectors. We have 15 combinations of two zeros times 16 possible signs gives 240 vectors; plus 6 unit vectors times 2 for signs gives 240+12=252 vectors. Multiply it by 3 using multiplication by ω we obtain 756 unit vectors in K12 lattice.
Further reading
The Coxeter–Todd lattice is described in detail in and .
References
External links
Coxeter–Todd lattice in Sloane's lattice catalogue
Quadratic forms
Lattice points | Coxeter–Todd lattice | [
"Mathematics"
] | 474 | [
"Lattice points",
"Quadratic forms",
"Number theory"
] |
14,777,805 | https://en.wikipedia.org/wiki/SALL1 | Sal-like 1 (Drosophila), also known as SALL1, is a protein which in humans is encoded by the SALL1 gene. As the full name suggests, it is one of the human versions of the spalt (sal) gene known in Drosophila.
Function
The protein encoded by this gene is a zinc finger transcriptional repressor and may be part of the NuRD histone deacetylase (HDAC) complex.
Clinical significance
Defects in this gene are a cause of Townes–Brocks syndrome (TBS) as well as branchio-oto-renal syndrome (BOR). Two transcript variants encoding different isoforms have been found for this gene.
Interactions
SALL1 has been shown to interact with TERF1 and UBE2I.
References
External links
GeneReviews/NCBI/NIH/UW entry on Townes-Brocks Syndrome
Further reading
Transcription factors | SALL1 | [
"Chemistry",
"Biology"
] | 193 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,777,833 | https://en.wikipedia.org/wiki/Barnes%E2%80%93Wall%20lattice | In mathematics, the Barnes–Wall lattice Λ16, discovered by Eric Stephen Barnes and G. E. (Tim) Wall (), is the 16-dimensional positive-definite even integral lattice of discriminant 28 with no norm-2 vectors. It is the sublattice of the Leech lattice fixed by a certain automorphism of order 2, and is analogous to the Coxeter–Todd lattice.
The automorphism group of the Barnes–Wall lattice has order 89181388800 = 221 35 52 7 and has structure 21+8 PSO8+(F2). There are 4320 vectors of norm 4 in the Barnes–Wall lattice (the shortest nonzero vectors in this lattice).
The genus of the Barnes–Wall lattice was described by and contains 24 lattices; all the elements other than the Barnes–Wall lattice have root system of maximal rank 16.
The Barnes–Wall lattice is described in detail in .
While Λ16 is often referred to as the Barnes-Wall lattice, their original article in fact construct a family of lattices of increasing dimension n=2k for any integer k, and increasing normalized minimal distance, namely n1/4. This is to be compared to the normalized minimal distance of 1 for the trivial lattice , and an upper bound of given by Minkowski's theorem applied to Euclidean balls. Interestingly, this family comes with a polynomial time decoding algorithm by .
Generating matrix
The generator matrix for the Barnes-Wall Lattice is given by the following matrix:
The lattice spanned by the following matrix is isomorphic to the above,
Lattice theta function
The lattice theta function for the Barnes Wall lattice is known as
where the thetas are Jacobi theta functions.
Note that the lattice theta functions for , are
where
References
External links
Barnes–Wall lattice at Sloane's lattice catalogue.
Quadratic forms
Lattice points | Barnes–Wall lattice | [
"Mathematics"
] | 384 | [
"Lattice points",
"Quadratic forms",
"Number theory"
] |
14,777,842 | https://en.wikipedia.org/wiki/Stacte | Stacte () and nataph () are names used for one component of the Solomon's Temple incense, the Ketoret, specified in the Book of Exodus (). Variously translated to the Greek term (AMP: ) or to an unspecified "gum resin" or similar (NIV: ), it was to be mixed in equal parts with onycha (prepared from certain vegetable resins or seashell parts), galbanum and mixed with pure frankincense and they were to "beat some of it very small" for burning on the altar of the tabernacle.
This incense was considered restricted for sacred purposes honoring Yahweh; the trivial or profane use of it was punishable by exile, as laid out in (KJV).
The Hebrew word nataf means "drop", corresponding to "drops of water" (). The Septuagint translates nataf as stacte, a Greek word meaning "an oozing substance," which refers to various viscous liquids, including myrrh.
Rabban Shimon ben Gamliel explained, "Stacte is simply the sap that drips from the tapping of the wood of the balsam tree" (Kerithot 6a). It is not exactly clear from what plant nataf was derived, however, it most likely was a myrrh extract of the highest grade or the light resin which exudes naturally from the myrrh tree before harvest. Alternately it may have been myrrh scented with styrax (Styrax officinalis or Styrax benzoin, a close relative of and of the same genus as Styrax officinalis) or opobalsamum (rare type of myrrh tree mentioned frequently in ancient Jewish writings as "balm" or "balsam").
Contenders for stacte
Myrrh extract
Most ancient sources refer to Stacte as being a product of myrrh. It is variously described as the transparent parts separated or extracted from the myrrh resin, the myrrh that exudes spontaneously from the tree, or the product of myrrh heated over fire.
The ancient Greek botanist Theophrastus described the manufacturing of stacte: "From the myrrh, when it is bruised flows an oil; it is in fact called "stacte" because it comes in drops slowly." The ancient Roman historian Pliny, in Natural History, described stacte as "the liquid which exuded naturally from the myrrh tree before the gum was collected from man-made incisions". Pancirollus described myrrh as a drop or tear distilling from a tree in Arabia Felix, and stacte as a drop of myrrh, which is extracted from it, and yielding a most precious liquid. Dioscorides wrote that stacte was made from myrrh. He recorded that after having bruised the myrrh and dissolved it in oil of balanos over a gentle fire, hot water was poured over it. The myrrh and oil would sink to the bottom like a deposit; and as soon as this has occurred, they strained off the water and squeeze the sediment in a press.
Ben-Yehoshua, et al., write "Stacte, which appears in the Bible in Exodus (30:34), probably refers to the liquid form of myrrh" and states that ancient writers referred to "a naturally flowing gum, called stacte, which sometimes flows from the bark of the tree without any cutting, before the actual harvest."
Stoddart, who lists myrrh as a balm, informs us that "Myrrh—after the almost clear stacte has passed through—is reddish brown ... Stacte is the thinnest moiety of myrrh, the very best of which is forced through tiny holes in the intact bark at the start of spring." Pomet wrote that to obtain stacte one must first gather the myrrh "that flows spontaneously from the tree" and to look for portions of the resin which are "clear and transparent, apt to crumble, light." He says to choose the myrrh "that when it is broke, has little white spots in it." We are told that "stacte is that liquid part which is found in the center or middle of the lumps or clots of myrrh." Pomet also wrote that stacte is that "which is first so gather'd from the tree without force, and also press'd from the myrrh ... there is prepar'd from it, an extract, an oil or liquor of myrrh."
The Gerrhaean tribute to Antiochus III in 205 BC included one thousand talents of frankincense and two hundred of "stacte myrrh."
Cant. 5:5 reads, "I rose up to open to my beloved; And my hands dropped with myrrh, And my fingers with stacte" referring to myrrh and the stacte which seems to have exuded from it. This would seem to agree with Sauer and Blakely who note that stacte was extracted from myrrh.
Abrahams informs that "With regard to the Tabernacle incense, most scholars agree that the term 'stacte' is of Latin and Greek origin, and that stacte represents myrrh." A. Lucas informs us in no uncertain terms that stacte is indeed a product of the myrrh tree. Tucker says that "Common myrrh is obtained from Commiphora myrrha; this is the species from which . . . stacte, was obtained."
R. Steuer, in his scholarly paper "Stacte in Egyptian Antiquity," gives a convincing argument in favor of stacte being the product of the myrrh tree in ancient Egypt.
Myrrh Extract scented with Benzoin is a possibility. Myrrh in antiquity and classical times was seldom myrrh alone but was a mix of myrrh and some other oil. Stacte may have been light myrrh scented with benzoin (benzoin is described in section 2.1 below).
According to Rosenmuller, stacte was myrrh and another oil mixed together. One definition of "myrrh" in the Merriam-Webster Dictionary is myrrh mixed with another aromatic oil. Writers in antiquity and classical times refer often to "mixed myrrh" and "scented myrrh". One kind of myrrh described by Dioscorides was "like the stacte, a composition of myrrh and some other ingredient." Then in another place he wrote that stacte was a mix of two fats (the first natural exudations of myrrh was often referred to as "the fat of fresh myrrh") which included styrax (referred to as storax in antiquity). Dioscordes defining stacte as Styrax and another substance and in another place as Myrrh and another substance seems to bring myrrh and storax together.
Although many scholars cite Styrax officinalis as the biblical storax, it exudes very little resin. This would seem to have necessitated the import of a storax such as Styrax benzoin, which is chemically similar and could have scented the slight bitter note of myrrh and met the demands of making large amounts of incense described in the Bible.
The book of Ecclesiasticus lists storax as one of the ingredients when alluding to the sacred incense of the biblical tabernacle, speaking of "a pleasant odour like the best myrrh, as galbanum, and onyx, and sweet storax, [in antiquity Styrax was referred to as Storax] and as the fume of frankincense in the tabernacle". Either myrrh was treated with storax or by the time of the first temple period a fifth ingredient was added to the ketoret. Myrrh may have been treated with storax or storax oil to further enhance the fragrance. Frederic Charles Cook's commentary on Exodus 30:34 says that it seems by no means unlikely that benzoin was part of the incense of Exodus 30. For centuries, myrrh has been scented with Styrax benzoin, particularly in the Middle East, to scent private homes and places of worship. Myrrh treated with Styrax benzoin exudes qualities similar to that of opobalsamum (Mecca myrrh).
Lucas and Steuer, however, independently insist that stacte is simply a form of myrrh (e.g., a myrrh extract or the light myrrh resin which exudes naturally without harvesting assistance).
Opobalsamum / Mecca Myrrh
Opobalsamum (Commiphora opobalsamum [L.] Engl. Mecca myrrh) is a rare type of myrrh in the genus Commiphora. Some writers believe that stacte was derived from the balsam tree, Commiphora opobalsamum, known as kataf in the Talmud, which grows wild in Yemen, around Mecca, and in Israel. The Revised Standard Version places "opobalsamum" in the margin by Exodus 30:34.
Gamliel said, "Stacte is simply the sap that drips from the tapping of the wood of the balsam tree" (Kerithot 6a). Iluz, et al., write that "researchers (Alpini, 1718; Feliks, 1995; Hepper, 1992; Linnaeus, 1764) have agreed with confidence that balsam is Commiphora gileadensis 1 (=C. opobalsamum), which grows wild today in the dry stony hills around the Red Sea." Ben-Yehoshua, et al., writing about "the most important spices used in religious ritual in ancient Israel" include opobalsamum referring to it as the "balm of Gilead, called also Judaean balsam, Hebrew—tzori, nataf, or Apharsemon (Exodus 30: 34)." Bos, et al., says that stacte is the "oil of the balsam tree, Commiphora opobalsamum, and features in Rabbinic literature."
In Fauna and Flora of the Bible, translators define stacte (nataf) as a resinous, aromatic gum exuding from Commiphora opobalsamum. Van Dam writes that stacte, which many equate with nataf, is a resinous aromatic gum of a balsam tree which he identifies as Commiphora opobalsamum. Some Latin texts of Exodus 30:34 translate stacte as a specie of myrrh, which Abraham states is opobalsamum.
From the genus Commiphora, opobalsamum is a relative of the official myrrh known as Commiphora myrrha and produces a myrrh resin known as Mecca myrrh. Irenaeus referred to "myrrh called opobalsamum." The juice exudes spontaneously during the heat of summer, in resinous drops, but at other times the process is helped by making incisions in the bark. It historically has produced a very pleasant aromatic resin with many alleged medicinal properties. The resin has a strong fragrant smell, with something of the lemon or citron flavour, a scent of vanilla, and the bitter, astringent aroma of Commiphora myrrha.
Lesser recognized contenders
There are several lesser recognized contenders for the title "Stacte" which should also be mentioned here:
Storax
Storax (Styrax officinalis, syn. S. officinale) is a species belonging to the family Styracaceae. Many modern authorities identify stacte with the gum of this storax tree and most commonly referred to by writers as Styrax officinalis. One source states that stacte is "the product of the Storax ... [T]he Septuagint name 'Stacte,' derived from the verb 'stazo,' to flow. By metonymy the name of the product, most probably, was transferred to the tree—as was the case in so many other instances among the ancient Israelites . . . [It] must not for a moment be confused or confounded with the Liquid Storax of commerce, which is the product of an altogether different Eastern tree . . . The Talmud contains several references to the Storax plant and its product. Of course in connection with the preparation of the holy incense for the Temple services."
The ancient book of Jubilees, part of the Dead Sea scroll collection found in Qumran, makes reference to storax. Carroll and Siler say that "The Septuagint's translation was most likely in error because it seems unlikely that nataph is a form of myrrh . . . it seems that its translation in the Septuagint as stacte was made simply because both nataph and stacte mean 'to drip' . . . the storax tree seems more likely. Our word storax may even come from the Hebrew tsori."
Benzoin (Styrax benzoin syn. Styrax tonkinensis) is a close relative of and of the same genus as Styrax officinalis above. In his commentary on Exodus 30:34 Frederic Charles Cook wrote that "it seems by no means unlikely that the stacte here mentioned was the gum known as Benzoin, or Gum Benjamin, which is an important ingredient in the incense now used in churches and mosks, and is the produce of another storax-tree (Styrax benzoin) that grows in Java and Sumatra."
Benzoin has a history steeped in antiquity and was once employed by the ancient Egyptians in the art of perfumery and incense. The apothecary of Shemot (Book of Exodus) would have been familiar with its aromatic uses. All the compounds identified in benzoin resin were detected in an archaeological organic residue from an Egyptian ceramic censer, thus proving that this resin was used as one of the components of the mixture of organic materials burned as incense in ancient Egypt. Morfit writes that the priests of Memphis burned benzoin incense every morning. The name "benzoin" is probably derived from Arabic lubān jāwī (لبان جاوي, "Javan frankincense"); compare the mid-eastern terms "gum benjamin" and "benjoin". H.J. Abrahams states that the use of benzoin in the Biblical incense is not inconceivable since Syro-Arabian tribes maintained extensive trade routes prior to Hellenism. Benzoin was available via import to the Biblical lands during the Old Testament era.
According to McClintock and Strong, the Hindustanis use benzoin to burn in their temples-which Strong and McClintoch write is a circumstance strongly in favor of the hypothesis that the stacte of Exodus is a storax.
Many scholars cite Styrax officinalis as the biblical storax, however the yield of resin produced by S. officinalis, if any is produced at all, is extremely small. The large amounts of stacte needed for liturgical purposes, especially in the first temple period, would seem to have necessitated the import of a storax that could have met the demand. Styrax benzoin yields a much larger yield of resin and could fill this need quite adequately. As mentioned above, Styrax benzoin is a close relative of and of the same genus as Styrax officinalis. Herodotus of Halicarnassus in the 5th century BC indicates that different kinds of storax were traded. Gamaliel said that stacte was nothing more than the sap that drips from the branches of the balsam tree. Balsam is a term that has been used for a variety of pleasantly scented vegetable gums that usually contain benzoic acid such as is contained in gum benzoin from the gum benzoin tree.
Dioscordes describes two kinds of stacte: one which is derived from myrrh and one which was derived from storax. He also refers to "another called gabirea ...it also yields much stacte." Houtman writes that stacte refers to myrrh, but is also used for other types of gums.
Rosenmeuller records that "the Greeks also called stacte, a species of storax gum, which Dioscorides describes, as transparent like a tear, and resembling myrrh." In the Orphic Hymns, the Greek word for storax is στόρακας or στόρακα.
One ancient Egyptian perfume formula (1200 BC) consisted of "storax, labdanum, galbanum, frankincense, myrrh, cinnamon, cassia, honey, raisins."
Again, the possibility exists that instead of being stacte itself, Benzoin may have been the agent used for scenting a Myrrh Extract (See section 1.1 above).
Liquidambar
It is believed by some that Liquidambar was the stacte of antiquity. This ancient product was discovered in King Tut's tomb.
Opoponax
Opoponax (Commiphora guidottii) is a member of the myrrh family and has been considered to have been stacte. It is sometimes referred to as opobalsamum, and is a relative of but not the true C. opobalsamum.
Balsam of Tolu and Balsam of Peru
Balsam of Tolu and Balsam of Peru (Myroxylon balsamum) are sometimes called opobalsamum and are sometimes substituted for it, however they are not the true C. opobalsamum. The balsams have a sweet, aromatic, resinous scent with an odour resembling vanilla or benzoin. Both Balsam of Tolu and Balsam of Peru come from the same tree, Myroxylon, but each differs in production. The word Myroxylon is literally "fragrant wood" in Greek, or Quina/Balsamo. The balsams substitute for opobalsamum which some believe to be stacte.
Mastic
Mastic (Pistacia lentiscus) is a bush which exudes an aromatic resin.
Myrrh extract and cinnamon mixed
Rosenmuller says that the etymology of the word stacte indicates "to distil", and that it was a distillate from myrrh and cinnamon which was mixed together.
Myrrh and Labdanum mixed
Moldenke writes that the myrrh of certain parts of Biblical history was actually labdanum. It is believed that many instances in the Bible where it speaks of myrrh it is actually referring to a mixture of myrrh and labdanum. According to the Merriam-Webster Dictionary one of the definitions of "myrrh" is "a mixture of myrrh and labdanum." If what was often referred to as myrrh was actually a mixture of myrrh and labdanum, then the manufacturing of stacte as described by Dioscorides could have reasonably been the product of this myrrh and labdanum mixture.
Labdanum
Labdanum (loT, stacte; translated "myrrh" in Genesis 37:25, margin "ladanum"; 43:11) The fragrant resin obtained from some species of cistus and called in Arabic ladham, in Latin ladanum. Stacte is described as resin which exudes naturally without a man-made incision. Labdanum exudes from the rock rose bush naturally without any incisions being made.
Oil of cinnamon
Stacte might have been the sweetly fragrant resin that used to exude spontaneously from Amyris kataf, the bark of which, in other opinions, is the biblical "cinnamon". or may have been the product of the cinnamon tree itself.
Jules Janick writes: "Stacte; unknown, probably oil of cinnamon or cassia or aromatic gem resins."
From Webster's Dictionary: "Stacte: one of the sweet spices used by the ancient Jews in the preparation of incense. It was perhaps an oil or other form of myrrh or cinnamon, or a kind of storax."
Balsam
Groom defines balsam as simply as "a viscous, resinous exudation from certain trees and shrubs, with a consistency which is thick but not solid. The principle balsams used in modern perfumery are Balsam of Peru, Balsam of Tolu, Balsam of Copaiba, Storax and Balm of Gilead [opobalsamum]. They have in common a vanilla like odor. The words balsam and balm are often used synonymously."
As stated above, some use Balsam of Tolu and Peru as a substitute for opobalsamum (Balm of Gilead), which they believe is the original stacte, because of the similarity of scent (opobalsamum is in the commiphora or the myrrh family). Groom describes the scent of these balsams as vanilla like and referring to Styrax benzoin, he says "the resin from it has a storax-like fragrance . . . and has a vanilla-like fragrance."
Gamaliel wrote, "Stacte is simply the sap that drips from the tapping of the wood of the balsam tree" (Kerithot 6a).
Footnotes
References
(2007): Stacte . Version of 07:35, 22 June 2007. Retrieved 2007-DEC-19.
(1915): Stacte. Retrieved 2007-DEC-19.
Incense material
Myrrh
Plants in the Bible | Stacte | [
"Physics"
] | 4,688 | [
"Incense material",
"Materials",
"Matter"
] |
14,777,889 | https://en.wikipedia.org/wiki/TBX3 | T-box transcription factor TBX3 is a protein that in humans is encoded by the TBX3 gene.
T-box 3 (TBX3) is a member of the T-box gene family of transcription factors which all share a highly conserved DNA binding domain known as the T-box. The T-box gene family consists of 17 members in mouse and humans that are grouped into five subfamilies, namely Brachyury (T), T-brain (Tbr1), TBX1, TBX2, and TBX6. Tbx3 is a member of the Tbx2 subfamily which includes Tbx2, Tbx4 and Tbx5. The human TBX3 gene maps to chromosome 12 at position 12q23-24.1 and consists of 7 exons which encodes a 723 amino acid protein (ENSEMBL assembly release GRCh38.p12).
Transcript splicing
Alternative processing and splicing results in at least 4 distinct TBX3 isoforms with TBX3 and TBX3+2a being the predominant isoforms. TBX3+2a results from alternative splicing of the second intron which leads to the addition of the +2a exon and consequently this isoform has an additional 20 amino acids within the T-box DNA binding domain. The functions of TBX3 and TBX3+2a may vary slightly across different cell types.
Structure and function
TBX3 has domains which are important for its transcription factor function which include a DNA-binding domain (DBD) also called the T-box, a nuclear localization signal, two repression domains (R2 and R1) and an activation domain (A). The T-box recognizes a palindromic DNA sequence (T(G/C)ACACCT AGGTGTGAAATT) known as the T-element, or half sites within this sequence called half T-elements, although it can also recognize variations within the consensus T-element sequences. While there are 29 predicted phosphorylation sites in the TBX3 protein only the SP190, SP692 and S720 have been fully characterized. The kinases involved are cyclin A-CDK2 at either SP190 or SP354, p38 mitogen-activated protein (MAP) kinase at SP692 in embryonic kidney cells and AKT3 at S720 in melanoma. These modifications act in a context dependent manner to promote TBX3 protein stability, nuclear localization and transcriptional activity.
TBX3 can activate and/or repress its target genes by binding a T-element, or half T-element sites. Indeed, Tbx3 binds highly conserved T-elements to activate the promoters of Eomes, T, Sox17 and Gata6, which are factors essential for mesoderm differentiation and extra embryonic endodermal. Furthermore, in the cancer context, TBX3 directly represses the cell cycle regulators p19ARF/p14ARF, p21WAF1 and TBX2 as well as E-cadherin which encodes a cell adhesion molecule, to promote proliferation and migration. TBX3 directly represses a region of the PTEN promoter which lacks putative T-elements, but which forms an important regulatory unit for PTEN transcriptional activators, thus raising the possibility that TBX3 may also repress some of its target genes through interfering with transcriptional activators.
The function of TBX3 as either a transcriptional repressor or transcriptional activator is, in part, modulated by protein co-factors. For example, it can interact with other transcription factors such as Nkx2-5, Msx 1/2 and Sox4 to assist it binding to its target genes to regulate heart development and it can interact with histone deacetylases (HDACs) 1, 2, 3 and 5 to repress p14ARF in breast cancer and with HDAC5 to repress E-cadherin to promote metastasis in hepatocellular carcinoma. Lastly, TBX3 can also co-operate with other factors to inhibit the process of mRNA splicing by directly binding RNAs containing the core motif of a T-element. Indeed, TBX3 interacts with Coactivator of AP1 and Estrogen Receptor (CAPERα) to repress the long non-coding RNA, Urothelial Cancer Associated 1 (UCA1), which leads to the bypass of senescence through the stabilization of p16INK4a mRNA.
TBX3 has been functionally connected to the regulation of the Wnt signalling, thereby providing a novel explanation of how signalling pathways are orchestrated by tissue-specific transcription factors.
Role in development
During mouse embryonic development, Tbx3 is expressed in the inner cell mass of the blastocyst, in the extraembryonic mesoderm during gastrulation, and in the developing heart, limbs, musculoskeletal structures, mammary glands, nervous system, skin, eye, liver, pancreas, lungs and genitalia. Tbx3 null embryos show defects in, among other structures, the heart, mammary glands and limbs and they die in utero by embryonic day E16.5, most likely due to yolk sac and heart defects. These observations together with numerous other studies have illustrated that Tbx3 plays crucial roles in the development of the heart, mammary glands, limbs and lungs. TBX3 has been implicated in the regulation of Wnt target genes by tissue-specific crosstalk with the protein BCL9.
Role in stem cells
Embryonic stem cells (ESCs) and adult stem cells, are undifferentiated cells which when they divide have the potential to either remain a stem cell or to differentiate into other specialized cells. Adult stem cells are multipotent progenitor cells found in numerous adult tissues and, as part of the body repair system, they can develop into more than one cell type but they are more limited than ESCs. TBX3 is highly expressed in mouse ESCs (mESCs) and appears to have a dual role in these cells. Firstly it can enhance and maintain stem cell pluripotency by preventing differentiation and enhancing self-renewal and secondly it can maintain the pluripotency and differentiation potential of mESCS. Induced pluripotent stem cells (iPSCs) are ESC-like cells that can generate scalable quantities of relevant tissue and are of major interest for their application in personalized regenerative medicine, drug screening, and for our understanding of the cell signaling networks that regulate embryonic development and disease. In vitro studies have shown that Tbx3 is an important factor that, together with KLF4, SOX2, OCT4, Nanog, LIN-28A and C-MYC, can reprogram somatic cells to form iPS cells.
Clinical significance
TBX3 has been implicated in human diseases including the ulnar mammary syndrome, obesity, rheumatoid arthritis and cancer.
In humans, heterozygous mutations of TBX3 lead to the autosomal dominant developmental disorder, ulnar mammary syndrome (UMS), which is characterized by a number of clinical features including mammary and apocrine gland hypoplasia, upper limb defects, malformations of areola, dental structures, heart and genitalia. Several UMS causing mutations in the TBX3 gene have been reported which include 5 nonsense, 8 frameshift (due to deletion, duplication and insertion), 3 missense and 2 splice site mutations. Missense mutations within the T-domain, or the loss of RD1 result in aberrant transcripts and truncated proteins of TBX3. These mutations lead to reduced DNA binding, transcriptional control and splicing regulation of TBX3 and the loss of function and are associated with the most severe phenotype of UMS.
Tbx3 is expressed in heterogenous populations of hypothalamic arcuate nucleus neurons which control energy homeostasis by regulating appetite and energy expenditure and the ablation of TBX3 function in these neurons was shown to cause obesity in mouse models. Importantly, Tbx3 was shown to be a key player in driving the functional heterogeneity of hypothalamic neurons and this function was conserved in mice, drosophila and humans. Genome wide association studies also causally linked TBX3 to rheumatoid arthritis (RA) susceptibility and a recent study identified Tbx3 as a candidate gene for RA in collagen-induced arthritis (CIA) mouse models. The severity of RA directly correlated with TBX3 serum levels in the CIA mouse models. Furthermore, Tbx3 was shown to repress B lymphocyte proliferation and to activate the humoral immune response which is associated with chronic inflammation of the synovium leading to RA. Tbx3 may thus be an important player in regulating the immune system and could be used as a biomarker for the diagnosis of RA severity.
TBX3 is overexpressed in a wide range of carcinomas (breast, pancreatic, melanoma, liver, lung, gastric, ovarian, bladder and head and neck cancers) and sarcomas (chondrosarcoma, fibrosarcoma, liposarcoma, rhabdomyosarcoma and synovial sarcoma) and there is compelling evidence that it contributes to several hallmarks of cancer. Indeed, TBX3 can bypass cellular senescence, apoptosis and anoikis as well as promote uncontrolled cell proliferation, tumor formation, angiogenesis and metastasis. Furthermore, TBX3 contributes to the expansion of cancer stem cells (CSCs) and is a key player in regulating pluripotency-related genes in these cells. CSCs contribute to tumor relapse and drug resistance and thus this may be another mechanism by which TBX3 contributes to cancer formation and tumor aggressiveness. The mechanisms by which TBX3 contributes to oncogenic processes involve, in part, its ability to inhibit the tumor suppressor pathways p14ARF/p53/p21WAF1/CIP1, p16INK4a/pRb, p57KIP2, PTEN, E-cadherin and activating the angiogenesis-associated genes FGF2 and VEGF-A and the EMT gene SNAI. Some of the oncogenic signaling molecules identified that upregulate TBX3 include TGF-β, BRAF-MAPK, c-Myc, AKT, and PLCᗴ/PKC. The function of TBX3 is also regulated by phosphorylation by the p38-MAPK, AKT3 and cyclin A/CDK2 and by protein co-factors, which include PRC2, Histone Deacetylases 1, 2, 3 and 5 and CAPERα.
There is also evidence that TBX3 may function as a tumour suppressor. During oncogenesis, TBX3 is silenced by methylation in some cancers and this was associated with a poor overall survival, resistance to cancer therapy and a more invasive phenotype. In addition, TBX3 is overexpressed in fibrosarcoma cells and removing TBX3 from these cells led to a more aggressive phenotype.
Notes
References
External links
Transcription factors | TBX3 | [
"Chemistry",
"Biology"
] | 2,417 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,778,022 | https://en.wikipedia.org/wiki/Geography%20of%20food | The geography of food is a field of human geography. It focuses on patterns of food production and consumption on the local to global scale. Tracing these complex patterns helps geographers understand the unequal relationships between developed and developing countries in relation to the innovation, production, transportation, retail and consumption of food. It is also a topic that is becoming increasingly charged in the public eye. The movement to reconnect the 'space' and 'place' in the food system is growing, spearheaded by the research of geographers.
History
Spatial variations in food production and consumption practices have been noted for thousands of years. In fact, Plato commented on the destructive nature of agriculture when he referred to the soil erosion from the mountainsides surrounding Athens, stating "[In previous years] Athens yielded far more abundant produce. In comparison of what then was, there are remaining only the bones of the wasted body; all the richer and softer parts of the soil having fallen away, and the mere skeleton of the land being left". Societies beyond those of ancient Greece have struggled under the pressure to feed expanding populations. The people of Easter Island, the Maya of Central America and most recently the inhabitants of Montana have been experiencing similar difficulties in production due to several interconnecting factors related to land and resource management. These events have been extensively studied by geographers and other interested parties (the study of food has not been confined to a single discipline, and has received attention from a huge range of diverse sources).
Modern geographers initially focused on food as an economic activity, especially in terms of agricultural geography. It was not until recently that geographers have turned their attention to food in a wider sense: "The emergence of an agro-food geography that seeks to examine issues along the food chain or within systems of food provision derives, in part, from the strengthening of political economy approaches in the 1980s".
Overlapping areas of study
Food has received attention from both the physical sciences and the social sciences because it is a bridge between the natural and social worlds. Some of the earliest numerical data about food production come from bureaucratic sources linked to the ancient civilizations of Ancient Egypt and the Roman Empire. Traders have also been influential in documenting food networks. Early Indian merchants and traders mapped the location of trading posts associated with food production nodes.
Food production
Food production was the first element of food to receive extensive attention from geographers in the field of cultural geography, particularly in agricultural geography.
Globally, the production of food is unequal. This is because there are two main components involved in sustenance production that are also distributed irregularly. These components are the environmental capacity of the area, and the human capacity. Environmental capacity is its ability ‘to accommodate a particular activity or rate of an activity without unacceptable impact’. The climate, soil types, and availability of water affect it. Human capacity, in relation to food production, is the size of the population and the amount of agricultural skill within that population. When these two are at ideal levels and partnered with financial capital, the creation of intense agricultural infrastructure is possible, as the Green Revolution clearly portrays.
Simultaneously, the ability of a country to produce food is being severely impacted by a plethora of other factors:
Pests are becoming resistant to pesticides, or pesticides may be killing off the useful and necessary insects. Examples of this happening occur around the globe. Tanzania experienced a particularly horrible infection of armyworms in 2005. At the infections peak, there were over 1000 larva per square meter. In 2009, Liberia experienced a state of emergency when invading African armyworm caterpillars began what became a regional food crisis. The caterpillars traveled through 65 towns and 20 000 people were forced to leave their homes, markets, and farms. Losses like this can cost millions to billions, depending on size and duration, and have severe effects on food security. The FAO has created an international team, the Plant Production and Protection Division, which is attempting to ‘reduce reliance on pesticides’ and ‘demonstrate that pesticide use often can be reduced considerably without affecting yields or farmer profits' in these, and other hard-struck areas.
Water stress, desertification, and erosion are leading to loss of arable land. Agricultural practices use the bulk of the Earth’s fresh water – up to 70 percent – and those numbers are predicted to rise by 50-100 percent by 2025’. Countries are being forced to divert more water than ever before to irrigate their land. Hydroelectric dams and mega-canal projects are becoming the new standard for countries like Egypt that can no longer depend on rainfall or natural flood cycles. These water shortages are also causing a source of conflict between neighboring nations as they live with increasingly high levels of water scarcity. Policy responses to these events could be implemented in order to strengthen the socio-economic growth, human health statuses, and environmental sustainability of these areas. Combining current limitations with water and transitions from practices such as agroforestry and shifting cultivation makes land susceptible to aeolian erosion by weakening soil composition and exposing larger areas of land to destructive wind. Aeolian erosion largely effects deserted areas, reducing air quality, polluting water sources, and limiting fertility of nearby land.
Climate change is creating more extreme weather patterns, and agricultural practices are estimated to cause from 10 to 12 percent of greenhouses gas emissions. Warming will increase the previously mentioned rates of desertification and insect activity and agricultural zones near the equator may be lost. However, due to the uneven warming that will probably occur, higher latitudes are expected to warm up at faster rates than other areas of the globe. Scientists are now presenting the idea that areas in Canada and Siberia may become suitable for farming at the industrial scale, and that those areas will be able to account for any farmland that is lost at the equator. Conservative estimates place the shift of traditional crops (maize, grain, potatoes) northward at 50 to 70 kilometers a decade. It is also believed that non-traditional crops (berries, sunflowers, melons) could be established on the southern sides of these countries. Changes in climate may force humans to adapt, adopt new practices, and alter old habits to promote success in the uncertain age of climate change ahead.
Food consumption
Criticisms of the industrialized food system regarding its inability to provide nutritious, ecologically sound, equitable food for the world's population has increased in recent history. Systems that are currently in place focus on providing relatively cheap food to millions, but often cost the Earth in terms of water and soil degradation, local food insecurity, animal welfare, rising obesity and health-related problems, and declining rural communities. Variations in diet and consumption practices on global and regional scales became the focus of geographers and economists with the vastly expanding population and widely publicized famines of the 1960s, and the food riots of 2007-2008 in 60 different countries. Due in part to these events, differences in the caloric intake of food and the composition of an average diet have been estimated and mapped for many countries since the 1960s.
Canada, USA, and Europe consume the highest amount of calories with an average per capita consumption of around 3400 calories daily. The recommended daily caloric intake for men and women living in these areas is 2500 and 2000 respectively. Studies focused on consumption patterns in these areas lay the blame for increased caloric intake on soft drink and fast food consumption, and decreased physical activity. Many developing countries are beginning to follow the leaders in rising caloric intake as they develop further due to increased availability of these high-impact items. Ballooning weight and associated health problems such as high blood pressure, high cholesterol, heart problems, and diabetes are being recorded in skyrocketing numbers.
Globally, consumption is still extremely uneven, with areas such as Sub-Saharan Africa still having some of the lowest rates of caloric intake per capita, often falling below the recommended levels. Much of this is due to lack of access of particular foods, which is a leading factor as to why much of the undernourished population is located in this region. In the world today, there are over 800 million people that are undernourished. The Democratic Republic of Congo holds the lowest average, at 1800 calories daily; however, averages do not represent the range of inequality between the best and worst fed people within a region. Currently, steps are being made to reduce caloric inequality. In parts of South Africa, the government has implemented a widespread electrification system featuring a free electricity allowance due to a study was conducted from 1991 to 2002 that found a positive increase in consumption habits within villages if given access to electricity. Access to electricity allowed for less time to be spent on menial tasks such as gathering firewood, and more time working on higher-level tasks that could increase income. In fact, villages often exceeded their electrical allowances.
See also
Local food
Food security
Right to food
Food rescue
Food speculation
References
External links
History of Thought Wiki: Geography of Food
Geography all the Way: Food Miles
Food Tank: The Food Think Tank
Food Manufacturing: The Leading Source for Food Manufacturing News
Zurich University of Applied Sciences - Research Group Geography of Food
Human geography
Food science
Agriculture | Geography of food | [
"Environmental_science"
] | 1,867 | [
"Environmental social science",
"Human geography"
] |
14,778,125 | https://en.wikipedia.org/wiki/CSDE1 | Cold shock domain-containing protein E1 is a protein that in humans is encoded by the CSDE1 gene.
References
External links
Further reading | CSDE1 | [
"Chemistry"
] | 30 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,778,146 | https://en.wikipedia.org/wiki/Melanoma%20inhibitory%20activity | Melanoma-derived growth regulatory protein is a protein that in humans is encoded by the MIA gene.
It is a marker for malignant melanoma.
References
Further reading
Human proteins | Melanoma inhibitory activity | [
"Chemistry"
] | 39 | [
"Biochemistry stubs",
"Protein stubs"
] |
14,778,193 | https://en.wikipedia.org/wiki/BHLHB2 | Class E basic helix-loop-helix protein 40 is a protein that in humans is encoded by the BHLHE40 gene.
Function
DEC1 encodes a basic helix-loop-helix protein expressed in various tissues. Expression in the chondrocytes is responsive to the addition of Bt2cAMP. Differentiated embryo chondrocyte expressed gene 1 is believed to be involved in the control of cell differentiation.
References
Further reading
External links
Transcription factors | BHLHB2 | [
"Chemistry",
"Biology"
] | 92 | [
"Induced stem cells",
"Gene expression",
"Transcription factors",
"Signal transduction"
] |
14,778,287 | https://en.wikipedia.org/wiki/MED6 | Mediator of RNA polymerase II transcription subunit 6 is one of the subunits of the Mediator complex. It is an enzyme that in humans is encoded by the MED6 gene.
Protein family
This family of proteins represent the transcriptional mediator protein subunit 6 that is required for activation of many RNA polymerase II promoters and which are conserved from yeast to humans.
Interactions
MED6 has been shown to interact with:
Cyclin-dependent kinase 8,
Estrogen receptor alpha,
MED21, and
Thyroid hormone receptor alpha.
References
Further reading
External links
Protein families | MED6 | [
"Biology"
] | 114 | [
"Protein families",
"Protein classification"
] |
14,778,324 | https://en.wikipedia.org/wiki/CARD11 | Caspase recruitment domain-containing protein 11 also known as CARD-containing MAGUK protein 1 (Carma 1) is a protein in the CARD-CC protein family that in humans is encoded by the CARD11 gene. CARD 11 is a membrane associated protein that is found in various human tissues, including the thymus, spleen, liver, and peripheral blood leukocytes. Similarly, CARD 11 is also found in abundance in various lines of cancer cells.
Function
The protein encoded by this gene belongs to the membrane-associated guanylate kinase (MAGUK) family, a class of proteins that functions as molecular scaffolds for the assembly of multiprotein complexes at specialized regions of the plasma membrane. This protein is also a member of the CARD protein family, which is defined by carrying a characteristic caspase-associated recruitment domain (CARD). CARD11 (CARMA1) has a domain structure similar to that of CARD10 (CARMA3) and CARD14 (CARMA2) as a member of the CARD-CC family with a C terminal MAGUK domain (the so-called CARMA proteins). The CARD domain of proteins in the CARD-CC family have been shown to specifically interact with BCL10, a protein known to function as a positive regulator of NF-κB activation by recruitment and activation of MALT1. When overexpressed in cells, this protein family activates NF-κB and induces the phosphorylation of BCL10.
CARD11 is critical for T cell and B cell function and is activated after T cell receptor or B cell receptor stimulation. After receptor stimulation, CARD11 is phosphorylated by PKC-θ (in T cells) or PKC-β (in B cells). The phosphorylation induces formation of filamentous CARD11 multimers that recruit BCL10 and MALT1, which in turn activates NF-κB. Loss of function mutations in CARD11 cause severe combined immunodeficiency (SCID) since the function of cells critical for adaptive immunity are disrupted.
Structure
The structure of CARD11 involves multiple domains that impact the protein's ability to activate BCL10 and NF-κB activity. CARD11 has a CARD domain, a serine-threonine rich region, is associated with the N-terminus, which is essential for NF-κB signaling activity. The region following the CARD domain is highly coiled. In deleting the CARD domain, all NF-κB signaling activity was prevented. The CARD domain on CARD11 interacts with the CARD domain on BCL10 to initiate the signaling pathway.
On the C-terminus of CARD11 there is the MAGUK domain that is associated with the cell membrane. This domain is often referred to as the inhibitory domain. Protein kinase C activates CARD11 by phosphorylating serine residues within the inhibitory domain.
Interactions
CARD11 has been shown to interact with BCL10. This interaction occurs between the CARD domain on BCL10 and the CARD domain on CARD11, and results in signal propagation and NF-κB activation.
References
External links
Further reading
Proteins | CARD11 | [
"Chemistry"
] | 664 | [
"Proteins",
"Biomolecules by chemical classification",
"Molecular biology"
] |
14,778,566 | https://en.wikipedia.org/wiki/Dunedin%20Astronomical%20Society | The Dunedin Astronomical Society Incorporated (DAS) is an amateur astronomical group operating from the Beverly-Begg Observatory Dunedin, New Zealand. It is affiliated with the Royal Astronomical Society of New Zealand and with the Otago Institute.
The objectives of the society are to:
Promote astronomy and telescope making
Maintain the Beverly-Begg Observatory and provide regular public viewing nights and astronomical instruction for privately arranged groups
Aid members by providing a regular programme of lectures and practical demonstrations on astronomical and telescope making topics
To provide access to astronomical equipment owned by the society to members and to upgrade such equipment as the society deems appropriate
Membership of the society is open to anyone interested in astronomy.
History
The Society was established on Monday 27 September 1910 by a meeting in "The Chemistry Room" of the University of Otago as the "Otago Astronomical Society". R. Gilkison was elected president with Rev. P. W. Fairclough and J. M. Garrow elected as vice-presidents. Thompson Lamb was Hon. Secretary and W. S. Wilson Hon. Treasurer.
In 1911 the Society affiliated with the Otago Institute to become the Astronomical Section of the institute. The following year a membership of 254 was reported in the transactions of the Royal Society of New Zealand (of which the Otago Institute was the Otago branch).
For a short time around 1915 the society had a "Telescope House" on Tanna Hill in the grounds of the Otago University. However the university required the land for a building project and the society had to look elsewhere for a permanent home. A site near the Dunedin Botanic Gardens was selected, but construction was delayed by World War I. In 1920 the current site for the Beverly-Begg Observatory in Belleknowes was chosen instead and construction of the observatory was completed in 1922.
In 1948 the Telescope Makers' Club asked to make use of the Society's facilities and subsequently joined with the Society.
In the 1960s the society built an annex on to the observatory to provide a more convenient area for meetings, talks and telescope construction.
The Dunedin Astronomical Society became an incorporated society in 2000 and was registered as a charitable society by the New Zealand Charities Commission in 2009.
In 2002 the society gained access to a cottage near Middlemarch for use as a dark sky site.
Centennial Celebrations
In 2010 DAS celebrated its centennial year with range of activities. As a part of the celebrations through the year the RASNZ Conference was hosted by the Society at the Otago Museum.
The main centennial events however started on Monday 27 September 2010 when a public meeting was held by the Society in the same room that was used for the meeting that established the society 100 years to the day previously. The minutes of the original meeting were read and a motion was passed taking the minutes as a true and accurate record (although none of those present at the 2010 meeting had been present at the previous meeting). Motions honouring the past officers of the Society and the association the Society had enjoyed with the Otago Institute were passed with acclamation. A talk was then given by amateur astronomer Dr. Grant Christie of Auckland's Stardome Observatory concerning the changes in our understanding of astronomy and the universe during the last 100 years.
During the following weekend a tour by bus of various sites of historical astronomical interest was conducted and culminated with the unveiling of a plaque on the University of Otago's Consumer and Applied Sciences (formally the Home Science building) near the site of the Society's first meeting and the site of the original "Telescope House".
Current activities
DAS meets twice a month through most of the year with meetings on the first and third Tuesday of each month (except January). The first meeting of each month generally features an astronomy related talk presented by a society member or an invited speaker. The second meeting of each month focuses more on practical astronomy in the form of an observation session (if the weather is kind), or discussion and examination of astronomical equipment and techniques.
During winter months (when daylight saving time is not in force) the society opens the Beverly-Begg Observatory to the public on Sunday nights starting at 7:00pm.
The society also makes access to the observatory available to education and private groups by arrangement.
Society members make regular use of The Cottage, a farm cottage near Middlemarch that is available for use as a dark sky site. In 2013 piers were installed to facilitate the use of the society's and member's Sky-Watcher EQ6 telescope mounts.
Science program
A magnetometer and data logger are installed at The Cottage to collect data for Dr. Yuki Obana of the Osaka Electro-Communication University. The data is used for solar wind research.
Society members are very active in occultation observation using the C14 telescope housed in the Beverly-Begg Observatory with a Watec astronomical video camera and IOTA-VTI video timing system.
A SBIG ST8300M camera is used for Astrometry and Photometry in several observation programs.
In 2015 members of the society recorded an important Pluto occultation on 29 June 2015 a couple of weeks before the New Horizons fly by of Pluto.
See also
List of astronomical societies
References
External links
Dunedin Astronomical Society website
Amateur astronomy organizations
Organisations based in Dunedin
Scientific organisations based in New Zealand | Dunedin Astronomical Society | [
"Astronomy"
] | 1,049 | [
"Amateur astronomy organizations",
"Astronomy organizations"
] |
14,778,811 | https://en.wikipedia.org/wiki/Webcam%20model | A webcam model (colloquially, camgirl, camboy, or cammodel) is a video performer who streams on the Internet with a live webcam broadcast. A webcam model often performs erotic acts online, such as stripping, masturbation, or sex acts in exchange for money, goods, or attention. They may also sell videos of their performances. Once viewed as a small niche in the world of adult entertainment, camming became "the engine of the porn industry," according to Alec Helmy, the publisher of XBIZ, a sex-trade industry journal.
As many webcam models operate in the comfort of their own homes, they are free to choose the amount of sexual content for their broadcasts. While most display nudity and sexually provocative behavior, some choose to remain mostly clothed and merely talk about various topics, while still soliciting payment as tips from their fans. Webcam models are predominantly women, and also include noted performers of all genders and sexualities.
Background
The conceptual artist Jenny Ringley is considered the first camgirl. In 1996, as a student at Dickinson College, Ringley created a website called "JenniCam". Her webcam was located in her dorm room and automatically photographed her every few minutes. Ringley viewed her site as a straightforward document of her life. She did not wish to filter the events that were shown on her camera, so sometimes she was shown nude or engaging in sexual behavior, including sexual intercourse and masturbation. These images were then broadcast live over the Internet. Two years later, in 1998, she divided her website's access between free and paying.
Also in 1998, a commercial site called AmandaCam was launched. Amanda's site, like Ringley's, had multiple cameras around her house, which allowed people to look in on her. However, Amanda made an important early discovery that would influence the camming industry for decades to come – that a website's popularity could be greatly increased by enabling viewers to chat with a performer while online. Within her members section, Amanda made it a point to chat with her viewers for over three hours a day. Since the early days of live webcasts by Ringley and Amanda, the phenomenon of camming has grown to become a multibillion-dollar industry, which has an average of at least 12,500 cam models online at any given time, and more than 240,000 viewers at any given time.
Payment systems and earnings
A camming website acts as an intermediary and aggregator by hosting independent models, and verifies that all are at least 18 years old. Camming websites typically fall into two main categories, dependent upon whether their video chat rooms are free or private. Viewers in private chat rooms pay the performance by the minute. In free chat rooms, payment is voluntary in the form of tips.
Tips are electronic tokens that viewers can buy from a camming website, and then give to the models during live performances to show appreciation. Tokens can also be used to buy access to private shows, operate a Teledildonic device that a model may be wearing, or buy videos and souvenirs from a model. The website provides the transactional platform and then collects and distributes a percentage of the tips to the models. For public chat rooms, the model's portion of a tip ranges from 30% to 70%, depending on the cam site.
A July 2020 survey found the average webcam model in the United States works 18 hours per week, and earns $4,470 per month. Webcam models who work full-time (40 hours per week or more) earn $11,250 per month on average. Top-earning webcam models have a self-reported income of over $312,000 annually, while bottom earners take home as little as $100 per week.
US taxes
In the United States, webcam models are considered as self-employed workers, and their tax rate is 15.3% (where 12.4% is for social security and 2.9% for Medicare), plus income tax. If a webcam model earns more than $600 in a year, they are sent a 1099 form and are required to report the income to the IRS.
Personal connection and interaction
Performances can be interactive in both public and private video chat rooms, as viewers and performers can communicate with each other using a keyboard, speech, and two-way cameras. Within public chat rooms, the audience can see tips and viewer comments as scrolling text next to the real-time video stream. Camgirls will frequently read and respond to the scrolling viewer comments. The chatter is constant and is often led by a small band of regular fans.
This is not the first time conversational interaction has become a boon for the erotic entertainment industry. In the early 20th century, sociologist Paul Cressey noted that within the hundreds of taxi-dance halls of America, "the traffic in romance and feminine society" would become available when taxi dancers would offer their companionship and "the illusion of romance" for ten cents a dance. The Mitchell Brothers O'Farrell Theatre strip club is credited with the invention of the lap dance in 1977 when their new stage, New York Live, pioneered customer-contact shows with strippers that came off the stage and sat in the laps of customers for tips. Enabled with this new revenue stream for strippers, the strip club industry went through a period of extreme growth during the 1980s.
There are often connections between erotic video performance and the everyday social lives of camming customers. Webcam performers are often highly entrepreneurial and use mainstream social networking sites such as Twitter, Instagram, Snapchat, Skype, and Tumblr to build and maintain relationships with their customers. Some fans communicate multiple times a day with models through social media.
Unlike traditional pornography, the interactive nature of the camming medium titillates with the promise of virtual friendship. Princeton University sociologist and author of The Purchase of Intimacy, Viviana Zelizer, states of camming: "they're defining a new kind of intimacy. It's not traditional sex work, not a relationship, but something in between." In addition to performing sex work, cam models also perform through their hosting duties, conveying authenticity, creating and animating fantasies, and managing relationships over time.
Within Cam Girlz, a documentary film about the industry, male fans often say that they come to camming sites as a way to fulfill emotional needs. The film's director, Sean Dunne, states of the fans, "they said it's not like a strip club – it's like a community, and you feel it when you're in these chat rooms. It's a community and entertainment that goes very far beyond sexuality."
However, Dr Kari Lerum of the University of Washington suggests that men are more open and vulnerable in cam rooms than in strip clubs, and can become very invested in relationships which only exist on the screen. This proposition was supported by a 2019 study of over 6,000 webcam users by the webcam platform Stripchat. The study found that over 40% of its users had developed significant relationships with their cam models, ranging from friendship to deep emotional connections.
Terminology
The term webcam is a clipped compound, combining the terms World Wide Web and video camera.
When webcam models create live webcasts, the activity is known as camming. A third-party hosting website which transmits multiple webcam models' video-streams is known as a camming site. Webcam models mostly perform individually in separate video chat rooms, frequently referred to as rooms.
The generally derogatory and pejorative term camwhore was used in print as early as November 2001. While commonly applied to sexually explicit performers, the term has also been applied to non-explicit female livestreamers on platforms such as Twitch and YouTube.
Camming industry
As of 2016, the money generated by camming sites was upwards of US$2 billion annually. The pornography business as a whole is estimated to be about $5 billion. According to the web traffic analysis service Compete.com, LiveJasmin generates more than 9 million unique viewers a month. Similar webcam model hosting sites such as Chaturbate, CAM4, and MyFreeCams boast 4.1 million, 3.7 million and 2 million unique monthly visitors, respectively. Certain hosting sites such as the aforementioned Chaturbate, LiveJasmin, ManyVids, and many other providers also offer payment in cryptocurrency.
The decentralized business model of camming has upended the pornography industry in multiple ways. Camming revenue has been severely cutting into the profits of the pornographic movie business, which has also been eroded for several years by piracy and the distribution of free sexual content on the Internet. The pornographic film industry used to be male-dominated, except for the performers. Since camming requires only a video camera, broadband service, and a computer, there has now been a power reversal, and female webcam performers are driving the industry. Todd Blatt, a former pornographic movie producer, has said, "If you're the middle guy who has been eating off this industry for 20 years, it's a big change. The girls don't need anybody."
The new revolution that the decentralized camming industry has brought also challenged many cultural stereotypes concerning both the camgirls and their customers. Ethnography researcher Dr Theresa Senft became a camgirl for a year while doing four years of research for her 2008 book Camgirls: Celebrity and Community in the Age of Social Networks. Senft has described herself as "the first academic camgirl" while becoming a "camgirl writing about camgirls." Anna Katzen, a camgirl who has a postgraduate degree from Harvard, stated during an interview:
Furthermore, she says that:
During the COVID-19 pandemic, the webcamming industry experienced explosive growth. The popular platform OnlyFans reported $2.4 billion in transactions in 2020, a 600% increase from 2019. This was driven in part by a large influx of new creators with little or no previous experience in sex work who joined the platform due to unemployment.
Hosting websites
Webcam models typically make use of third-party websites to stream their real-time video performances on the Internet. Some sites charge viewers a fixed fee per minute, although many allow free access for unregistered visitors. These Internet hosting websites, known as camming sites, take care of the technical work hosting the video feed broadcast, processing payments, providing an intuitive interface, advertising so that the cam model only has to focus on the actual shows for their video chat room.
A fee can be charged for service as a percentage of the revenue made by the model. To improve security and anonymity, some webcamming services (such as Live Stars) use blockchain technology to handle the payment and to protect the model's entered personal information. SpankChain is another similar camming site and cryptocurrency.
By presenting hundreds of different models via individual chat rooms, a camming site becomes a talent aggregator and middleman. Though a camming website may carry many hundreds of models, they frequently provide an interface for the viewer to easily switch between the most-visited models' rooms, and that interface occasionally resembles the multiple channel selection of cable television.
Most cam models are independent contractors for camming sites, and are not employees.
Camming sites typically supply each webcam model with an individual profile webpage where the performer can describe themselves and more importantly, create a virtual store where they can sell items like videos, photos, personal clothing, and memberships to their fan club. The profile page's virtual store creates a stream of passive income, meaning that even if a camgirl is not online and performing, she can still generate money while fans come to the ever-present profile page to purchase its wares. Some of the most popular items are homemade videos cam models make of themselves. While most of these videos are sexual in nature, they often include elements of comedy, fashion, and a narration of their lifestyles.
The affordability of and access to new video recording technology has spawned new variations and genres of pornography since individual women, as well as industry players, can now create content. A profile page might also sell contact information like a personal phone number, a spot on a model's Snapchat contact list, or the ability to send her private messages through a camming site's friends list. The profile page may also suggest tip amounts for real-time performance requests, like a sexy dance, a song request, removal of clothing, or a particular sex act. All prices on a profile page are listed in quantities of tips, which are electronic tokens that the viewer can buy in bunches from the cam site to be given to various models during the performance, or in later purchases upon the profile page.
The camming site keeps a percentage of the tips, and the amount varies. Big earners can get a bigger chunk of their tips. Commissions earned by webcam models vary widely by website and are usually based on a percentage of gross sales, although sometimes they are in the form of a flat fee. They may also earn money through advertising or commissions by persuading customers to sign up for membership at adult pornographic paysites. Many sites encourage viewers to purchase items from online wish lists. Some webcam models cater to particular fetishes, such as a fascination with feet, and might earn additional money by selling worn socks to patrons. Some models will cater to extremely specific fetishes, as customers with uncommon fetishes tend to pay more. This has been criticized as a "race to the bottom," where webcam models will attempt to outdo each other in perversity. In reaction, cam models on websites such as Chaturbate have developed a culture discouraging engagement in fetishes they consider demeaning.
Camming sites specify rules and restrictions for their cam models, which in turn tend to give the camming site a distinct style and format. For example, one major free-access site, which only allows female models, fosters an environment where the camgirls are not necessarily obligated to do masturbation shows or even display nudity. Consequently, some of that site's models create a more relaxed "hangout atmosphere" within their rooms that occasionally resembles a talk show. Conversely, another major cam site, which allows men and couples to perform, tends to be more sexual and show-oriented. On some sites, models are not required to show their face on the webcam stream (thus allowing the use of veils, masks, ...). Other cam site rules might prohibit working in a public place so that the model does not get a public indecency arrest, the way that Kendra Sunderland was charged after her 2014 performance inside the Oregon State University Library. Models who violate a camming site's rules may be subjected to a temporary or permanent ban from the cam site.
Social media
Webcam models often rely on social media to interact with existing customers and to meet new customers. This has potential disadvantages; however, mainstream social media platforms often have poorly-defined and changing rules that sex workers can inadvertently break. Having a social media account closed for any reasonlegitimate or otherwisecan severely affect a performer's ability to earn income.
Some cam models have non-commercial personal web blogs.
Resources for performers
Cam studios allow models to rent facilities outside of their homes. These businesses can supply models with video equipment, Internet service, computer, lighting, and furniture. One example was the pornographic film company Kink.com, which rented individual cam studios in the San Francisco Armory by the hour from 2013 until the building was sold in 2018.
Within some studios, cam models can work by the percentage of business that they bring in, instead of renting studio time. The cam models do not have to pay to join this type of studio and are also not guaranteed a salary. These models can typically charge customers between $1 and $15 per minute, and then the studio keeps half of the gross while the model gets the rest.
Another workplace option is called a "camgirl mansion", which is a place that provides equipment and broadcast rooms, where multiple camgirls can live and share expenses without a studio owner.
Various support websites supply general information about business strategies, upcoming conferences, performance tips, and studio equipment reviews. Support sites also advise on how to protect privacy, discourage piracy, avoid Internet security lapses, and prevent financial scams. Some chat websites for cam models provide message boards for the models, which enables them to discuss their work concerns and issues, such as clients who get overly attached.
Conferences and industry trade shows can also aid cam models by allowing cam models to network and meet others in the profession on a personal level. Cam model Nikki Night provides a coaching service for cam models, in which she advises them on business practices that maximize revenues.
Legal issues and risks
Laws
Due to the controversial nature of pornography, camming, like most sex work, is not considered a legitimate form of labor in most developed countries. As a result, cam models do not receive the same benefits and rights as other employees since they are technically independent contractors. This offers cam models some freedom not offered to other laborers but prevents them from demanding better treatment from the websites that host them. However, in-person sex work is treated more harshly since it is illegal in many Western countries, including the United States. Camming is considered slightly different, since it is considered pornography as a virtue of being filmed.
Regulation would be beneficial to camming, since it would prevent cam models from being exploited for their labor. However, regulation could also potentially take away cam models' independence, such as sexual freedom and bodily autonomy. Although in-person sex work such as prostitution can be regulated by policing the streets, online sex work is hard to regulate, due to anonymity, and risk of encroaching on content that is risqué, but not necessarily pornographic. In a study on sex work in East Java, Indonesia where a specific district decriminalized sex work while its surround districts did not, researchers found that anti-prostitution laws decreased the use of condoms, which in effect increased the transmission of sexually transmitted diseases such as HIV.
China
In accordance with the 1997 penal code, pornography is illegal in China. The law only permits educational or artistic depictions of sexual intercourse. Historically, the law is not interpreted by the government to include pornography under the umbrella of art. As such, camming faces strict regulation on the internet in contrast to Western countries, where its legal distinction protects it from prostitution. However, camming can also be a form of solace for sex workers since it allows them to escape online where they can avoid persecution for their profession.
China has planned to extend anti-camming laws to ASMR. The Chinese government claims that ASMR constitutes pornography, but Chinese ASMR content creators dispute this, arguing that pornographic ASMR represents a different category from non-sexual ASMR.
India
Sex work is legal in India, but many related elements such as brothels are illegal. Thus, camming is legal in India, but a social stigma remains. There is a narrative that sex workers in India are coerced into their profession, but this is not true of all sex workers. Many sex workers attest that their profession is legitimate labor and should be recognized as such. Due to the illegality of pimping, sex workers like cammers tend to operate independently and thus control their labor and profits.
Philippines
Sex work is illegal in the Philippines, but enforcement of the law is not strict such that it is quite commonplace. There is a perception that Filipino sex workers are victims of human trafficking, but this isn't always the case. Camming, in particular, is usually consensual and not always explicitly sexual, likening it more to performance than pornography.
United Kingdom
Sex work and camming in the United Kingdom is heavily regulated by the government. Sex work is not recognized as legitimate employment by the government. As a result, sex workers are often afraid to report crimes committed against them, making sex work a dangerous occupation. Sex workers, both online and offline, are often subject to stalking, unwanted messages, and other forms of harassment. It is hard to obtain concrete conclusions from studies on sex work in the UK due to its tenuous legality. Most studies are conducted through surveys which are subject to biases.
A sex work researcher, Rachel Stuart, notes a paradox in British law that tends to focus on the uploading of pornographic recordings, but does not deal with erotic performance when streamed upon the Internet through camming. For instance, the Audiovisual Media Services Regulations 2014 ban certain acts from being depicted and uploaded by pornography producers in the United Kingdom, and the Digital Economy Act 2017 seeks to restrict minors' access to pornographic material online, yet both laws will have no effect if the performances are streamed as opposed to recorded. Stuart states of the legal conundrum in England, "Performing an explicitly pornographic act via a webcam carries no repercussions, but if the same show is recorded and uploaded, the performer can be liable to a fine."
United States
Lawrence Walters, a Florida lawyer who is an expert in obscenity law, said that there was nothing inherently illegal about web model camming shows, as long as the models were over 18, and performed at home or in a model's studio.
Risks
While the conduct of webcam models' clients in chat rooms has been described as generally civil and polite, some models have faced "aggressive sexual language" and online harassment. In 2012, a group of 4chan users harassed a webcam model about her weight until she began crying on camera. Even clients who are polite can behave in ways that make models feel uncomfortable, such as when clients become overly attached to, or obsessive, about a model; if the client is a regular customer and a heavy tipper, this can make the model feel pressured to give in to the client's requests. Webcam models have occasionally been the targets of cyber-stalkers and blackmailers. Some cam models have been "blackmailed or threatened into performing acts they are not comfortable with. If they don't comply, they run the risk of having their real identity exposed". In one case, Internet trolls revealed the real name, address and phone number of a webcam performer and posted this information, along with explicit photos of her, on social media, and the account was forwarded to her friends and family. As of 2019, it was reported that there is little legal protection for cam models, as most of the case law deals with the regulation of strip clubs and sex shops, or for distribution of products.
Sex work researcher, Rachel Stuart, reported that while doing her PhD research she encountered webcam models who were concerned about viewers filming and sharing their performances on porn sites, or acquiring personal information which could be used to stalk or blackmail them. In 2013, the New York Times interviewed a woman who prefers to conceal her real identity while working as a camgirl. She revealed that she had been cyber-stalked by a heavy tipper who started making threats and demands about what outfits she should wear. A short while later, she found out that her real name and address had been posted on the Internet along with her cam name. When she complained to the police, they said that they could do nothing, because "putting real information on the Internet is not illegal." She later found out that the same individual had also threatened and outed several other camgirls.
Another issue faced by cam models is that viewers may record streams or images of the model without their consent and then redistribute them on pornography websites. In addition to taking away the model's ability to choose where their content is shown, unauthorized use has been likened to theft of the model's property, since the porn site will earn money from the video and not the cam model.
Sex workers have formed support groups where sex workers may give each other advice and possibly cope with harassment and marginalization. The word "camily", a portmanteau of "cam" and "family", refers to communities formed by sex workers to help deal with such issues.
Incidents
1990s
A New York Times report described the story of Justin Berry, a 13-year-old boy who, after hooking up his webcam and listing himself on an online forum in order to make friends, was propositioned by older men to strip and masturbate on camera. CNN referred to him as "in the language of cyberspace... a cam-whore". He started his own paysite, prostituted himself, sold video recordings of his encounters with Mexican prostitutes, and helped hire other underage models. He made several hundred thousand dollars over five years before turning all information over to prosecutors in exchange for immunity.
2010s
In October 2014, a 19-year-old Oregon State University student, Kendra Sunderland, had been working as a camgirl before she made an hour-long video for MyFreeCams.com of herself at the Oregon State University Library, in which she stripped and masturbated on camera for a live audience. She was then charged with public indecency after the show was recorded by someone who was watching MyFreeCams.com online, and then posted it on other sites. Sunderland faced fines up to $6,250 and one year of jail. She pleaded guilty, paid $1,000, and avoided jail. The incident generated headlines around the country and landed Sunderland reported deals with Playboy, and a contract with Penthouse's parent company Friend Finder Networks purportedly worth six figures. The incident greatly increased Sunderland's popularity, and she has continued to do camming and speak positively of it as a career.
In Arizona during 2015, a fan took his appreciation of camgirls to an illegal level when he was indicted for spending $476,000 on a company credit card, which he used for tips on camming websites. He spent more than $100,000 on MyFreeCams.com alone, and sent $26,800 to one cam model in particular to pay for her college tuition bill and new tires for her car. According to the indictment, he also purchased flowers, chocolates, electronic equipment, shoes, a TV, a handbag, laptop computer, and an iPod for some of his favorite camgirls.
In one case, sex traffickers who operated illegal brothels forced an indentured victim to have sex in webcam shows.
In January 2019, a 29-year-old Grant Amato killed his father, mother and brother and staged the scene as a murder-suicide, placing the gun by his brother's body. His motivation was an argument with his parents about his infatuation with a webcam model.
See also
Adult content subscription service
American burlesque
Cybersex
Exhibitionism
Internet pornography
Lap dance
List of chat websites
LittleRedBunny
Parasocial interaction
Sex show
Striptease
Talk show
Taxi dancer
Voyeurism
References
Further reading
External links
Sexuality and computing
Online content distribution
Internet culture
Sex workers
2000s neologisms
Sex industry
Streaming | Webcam model | [
"Technology"
] | 5,585 | [
"Multimedia",
"Streaming",
"Computing and society",
"Sexuality and computing"
] |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.