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16,722,280 | https://en.wikipedia.org/wiki/Milk%20kinship | Milk kinship, formed during nursing by a non-biological mother, was a form of fostering allegiance with fellow community members. This particular form of kinship did not exclude particular groups, such that class and other hierarchal systems did not matter in terms of milk kinship participation.
Traditionally speaking, this practice predates the early modern period, though it became a widely used mechanism for developing alliances in many hierarchical societies during that time. Milk kinship used the practice of breast feeding by a wet nurse to feed a child either from the same community, or a neighbouring one. This wet nurse played the strategic role in forging relations between her family and the family of the child she was nursing, as well as their community.
Strategic reasons for milk kinship
"Colactation links two families of unequal status and creates a durable and intimate bond; it removes from 'clients' their outsider status but excludes them as marriage partners...it brings about a social relationship that is an alternative to kinship bonds based on blood." People of different races and religions could be brought together strategically through the bonding of the milk mother and their milk 'children'.
Lower social class
Milk kinship was as relevant for peasants as 'fostering' or as 'hosting' other children, in that it secured the good will from their masters and their wives. As previously mentioned the milk women's family is the 'core range' to the child she is nursing and they become milk kin, which may strategically be useful for the future if the child is from a higher class family, as the milk women's children will become 'milk-brothers' and 'milk-sisters.' Thus peasant women would most often play the role of the 'milk' mother to her non-biological children, and they held an important role in maintaining the connection between herself and the master whose baby she is nursing. It was also a practical way to assist families who were of a very ill mother or whose mother died in childbirth. This would have been helpful in many societies where, especially in times of war, if families perished, other members of society would end up co-parenting through the link of milk-kinship.
Higher social class
Noble offspring were often sent to milk kin fosterers that would foster them to maturity so that the children would be raised by their successive status subordinates. The purpose of this was for political importance to build milk kin as bodyguards. This was a major practice in the Hindu Kush society.
Conflicting theories, ideas and myths
One particular theory mentioned by Peter Parkes is an Arab folk-analogy that breast milk is supposed to be "transformed male semen" that arises from Héritier's Somatic Scheme. There is no evidence that Arabs ever considered a mother's milk to be 'transformed sperm'. Another suggested analogy is that breast milk was a refinement of uterine blood. It is also suggested since that milk is of the woman, her moods and dispositions are transferred through the breast milk. Parkes mentions that milk-kinship was "further endorsed as a canonical impediment to marriage by several eastern Christian churches". This indicates that this procedure was widely practiced among numerous religious communities, not just Islamic communities, in the early modern Mediterranean.
Héritier's somatic thesis
Soraya Altorki (1980) published a pioneering article on Sunni Arab notions of kinship created through suckling breast milk (Arabic: rida'a orrada'''). Altorki indicated that milk kinship had received little attention from anthropologists, despite its recognised significance in Muslim family law as a complex impediment to marriage. Milk kinship has since attracted further fieldwork throughout Islamic Asia and North Africa, demonstrating its importance as a culturally distinctive institution of adoptive affiliation.
Héritier's somatic thesis posits that Islamic marriage between milk kin is forbidden because of an ancient pre-Islamic meme that is communicated in the Arab saying 'the milk is from the man'. Héritier's somatic explanation has since been endorsed – and apparently confirmed – by several French ethnographers of the Maghreb, also being further developed in her monograph on incest.
In reaction, a few scholars have cited Islamic commentaries and jurisprudence. "A child is the product of the conjoint seed of man and woman . . . but milk is the property of woman alone; one should not conflate by analogy (qiyas) milk with male semen." Al-Qurtubi, Jami' al-ahkam V.83, cited in Benkheira (2001a: 26). The rules of Sunni marital incest apply through a standard of adoptive kin relations. But the modern jurisprudence does not negate nor explain the origin of the taboo.
Héritier explains Islamic juridical reckonings of milk kinship as the continuation of a somatic scheme of male filiative substances transmitted by lactation. But Parker critically interrogates its supposition of a peculiar Arab folk-physiology of lactation, whereby breast milk is supposed to be transformed male semen, yet mentions that Héritier has properly focused attention on evidently contested issues of 'patrifiliation' by breast-feeding, which remain to be understood. Parker posits that this somatic scheme seems to be unsubstantiated by current ethnographies, and also unwarranted in understanding the juridical reckoning of milk kinship that it purports to explain.
Practices in different societies
In Eastern Christianity
Weisner-Hanks mentions the introduction in the fifteenth century of prohibitions in the Christian Canon Law, in which one is not allowed to marry any one suspected to be of respective kin. Individuals who shared godparents, and great grandparents were prohibited against marrying. The prohibitions against marriage also extended to that of natural godparents. This was because both natural and 'foster' or 'spiritual' parents had an investment on the child's spiritual well being, which would not be achieved by going against Canon Law. The practice of milk kinship is paralleled quite frequently, among scholarly works, with that of Christian godparent-hood or spiritual kinship. Parkes states that in both milk kinship and god-or co-parenthood "we deal with a fictitious kinship relationship between people of unequal status that is embedded in a long-term exchange of goods and services that we know as patronage". Iranians seemed to have "taken care to confine delegated suckling to subordinate non-kin – particularly those with whom marriage would be undesirable in any event". Marriage taboos due to milk kinship were taken very seriously since some regarded breast milk to be refined female blood from the womb, thus conveying a 'uterine substance' of kinship. Children who were milk kin to each other were prohibited to marry as well as two children from different parents who were suckled by the same woman. It was as much of a taboo to marry your milk-brother or -sister, as it was to marry a biological brother or sister. It is extremely important to understand that in all cases "What is forbidden by blood kinship is equally forbidden by milk kinship".
In Islamic societies
In the early modern period, milk kinship was widely practiced in many Arab countries for both religious and strategic purposes. Like the Christian practice of godparenting, milk kinship established a second family that could take responsibility for a child whose biological parents came to harm. "Milk kinship in Islam thus appears to be a culturally distinctive, but by no means unique, institutional form of adoptive
The childhood of the Islamic prophet, Muhammad, illustrates the practice of traditional Arab milk kinship. In his early childhood, he was sent away to foster-parents amongst the Bedouin. By nursing him, Halimah bint Abdullah became his "milk-mother". The rest of her family was drawn into the relationship as well: her husband al-Harith became Muhammad's "milk-father", and Muhammad was raised alongside their biological children as a "milk-brother". This milk kinship creates a familial relationship, such that a man may not marry his milk-mother or his milk-sister (the daughter or milk-daughter of his milk-mother).
In Native American societies
When Crazy Horse, a 19th-century Lakotan chief, was a baby, he nursed at the breast of every woman in the tribe. The Sioux raised their children that way. Every warrior called every old woman in the tribe "Mother". Every old warrior, they called him "Grandfather".
See also
Affinity (Catholic canon law) marriages prohibited due to marriage or sexual intercourse
Consanguinity marriages prohibited due to blood relations
Inclusive fitness in humans
Rada (fiqh)
References
Bibliography
Altorki. Soraya. 1980. 'Milk Kinship in Arab Society: An Unexplored Problem in the Ethnography of Marriage', Ethnology, 19 (2): 233–244
El Guindi, Fadwa. 'Milk and Blood: Kinship among Muslim Arabs in Quatar', Anthropos: International Review of Anthropology and Linguistics, 107 (2): 545–555.View
Ensel, R. 2002. 'Colactation and fictive kinship as rites of incorporation and reversal in Morocco', Journal of North African Studies 7: 83–96.
Giladi, A. 1998. 'Breast-feeding in medieval Islamic thought. A preliminary study of legal and medical writings', Journal of Family History 23: 107–23.
Giladi. A. 1999. Infants, parents and wet nurses. Medieval Islamic views on Breast-feeding and their social implications. Leiden: Brill.
Parkes, Peter. 2005. 'Milk Kinship in Islam. Substance, Structure, History', Social Anthropology 13 (3) 307–329.
Soler, Elena. 2010. "Parentesco de leche y movilidad social. La nodriza pasiega" Giovanni Levi (coord) Familias, jerarquización y movilidad social. Edit.um
Weisner-Hanks, M. 2006. Early Modern Europe, 1450–1789. New York: Cambridge University Press. p. 74.
Moore, H. and Galloway, J. 1992. We Were Soldiers Once... And Young. New York: Random House.
Further reading
Parkes, Peter. 2004. 'Fosterage. Kinship, and Legend: When Milk Was Thicker than Blood?', Comparataive Studies in Society and History'' 46 (3): 587–615
Soler, Elena (2011). Lactancia y parentesco. Una Mirada antropológica. Anthropos
External links
Fictive Kinship: Making Maladaptation Palatable
Kinship and descent
Wet nursing
Islamic culture
Eastern Christianity | Milk kinship | Biology | 2,216 |
20,854,070 | https://en.wikipedia.org/wiki/Hen%202-47 | Hen 2-47 is a young planetary nebula that lies about 6600 light years away from Earth in the southern constellation of Carina, the keel.
Hen 2-47 contains six lobes of gas and dust that suggest that the central star of the nebula ejected material at least three times in three different directions. During each ejection, the star fired off a narrow pair jets of gas pointed in opposite directions, eventually giving the nebula the shape it has at present.
References
Planetary nebulae
Carina (constellation) | Hen 2-47 | Astronomy | 104 |
7,583,397 | https://en.wikipedia.org/wiki/Tortuosity | Tortuosity is widely used as a critical parameter to predict transport properties of porous media, such as rocks and soils. But unlike other standard microstructural properties, the concept of tortuosity is vague with multiple definitions and various evaluation methods introduced in different contexts. Hydraulic, electrical, diffusional, and thermal tortuosities are defined to describe different transport processes in porous media, while geometrical tortuosity is introduced to characterize the morphological property of porous microstructures.
Tortuosity in 2-D
Subjective estimation (sometimes aided by optometric grading scales) is often used.
The simplest mathematical method to estimate tortuosity is the arc-chord ratio: the ratio of the length of the curve (C) to the distance between its ends (L):
Arc-chord ratio equals 1 for a straight line and is infinite for a circle.
Another method, proposed in 1999, is to estimate the tortuosity as the integral of the square (or module) of the curvature. Dividing the result by length of curve or chord has also been tried.
In 2002 several Italian scientists proposed one more method. At first, the curve is divided into several (N) parts with constant sign of curvature (using hysteresis to decrease sensitivity to noise). Then the arc-chord ratio for each part is found and the tortuosity is estimated by:
In this case tortuosity of both straight line and circle is estimated to be 0.
In 1993 Swiss mathematician Martin Mächler proposed an analogy: it’s relatively easy to drive a bicycle or a car in a trajectory with a constant curvature (an arc of a circle), but it’s much harder to drive where curvature changes. This would imply that roughness (or tortuosity) could be measured by relative change of curvature. In this case the proposed "local" measure was derivative of logarithm of curvature:
However, in this case tortuosity of a straight line is left undefined.
In 2005 it was proposed to measure tortuosity by an integral of square of derivative of curvature, divided by the length of a curve:
In this case tortuosity of both straight line and circle is estimated to be 0.
Fractal dimension has been used to quantify tortuosity. The fractal dimension in 2D for a straight line is 1 (the minimal value), and ranges up to 2 for a plane-filling curve or Brownian motion.
In most of these methods digital filters and approximation by splines can be used to decrease sensitivity to noise.
Tortuosity in 3-D
Usually subjective estimation is used. However, several ways to adapt methods estimating tortuosity in 2-D have also been tried. The methods include arc-chord ratio, arc-chord ratio divided by number of inflection points and integral of square of curvature, divided by length of the curve (curvature is estimated assuming that small segments of curve are planar). Another method used for quantifying tortuosity in 3D has been applied in 3D reconstructions of solid oxide fuel cell cathodes where the Euclidean distance sums of the centroids of a pore were divided by the length of the pore.
Applications of tortuosity
Tortuosity of blood vessels (for example, retinal and cerebral blood vessels) is known to be used as a medical sign.
In mathematics, cubic splines minimize the functional, equivalent to integral of square of curvature (approximating the curvature as the second derivative).
In many engineering domains dealing with mass transfer in porous materials, such as hydrogeology or heterogeneous catalysis, the tortuosity refers to the ratio of the diffusivity in the free space to the diffusivity in the porous medium (analogous to arc-chord ratio of path). Strictly speaking, however, the effective diffusivity is proportional to the reciprocal of the square of the geometrical tortuosity
Because of the porous materials found in several layers of fuel cells, the tortuosity is an important variable to be analyzed. It is important to notice that there are different kind of tortuosity, i.e., gas-phase, ionic and electronic tortuosity.
In acoustics and following initial works by Maurice Anthony Biot in 1956, the tortuosity is used to describe sound propagation in fluid-saturated porous media. In such media, when frequency of the sound wave is high enough, the effect of viscous drag force between the solid and the fluid can be ignored. In this case, velocity of sound propagation in the fluid in the pores is non-dispersive and compared with the value of the velocity of sound in the free fluid is reduced by a ratio equal to the square root of the tortuosity. This has been used for a number of applications including the study of materials for acoustic isolation, and for oil prospection using acoustics means.
In analytical chemistry applied to polymers and sometimes small molecules tortuosity is applied in gel permeation chromatography (GPC) also known as size exclusion chromatography (SEC). As with any chromatography it is used to separate mixtures. In the case of GPC the separation is based on molecular size and it works by the use of stationary media with an appropriate porous microstructure and adequate pore dimensions and distribution. The separation occurs because larger molecules cannot enter the smaller porosity for steric hindrance reasons (constrictivity of the narrow pores) and remain in the macropores, eluting more quickly, while smaller molecules can pass into smaller pores and take a longer, more tortuous path and elute later.
In pharmaceutical sciences, tortuosity is used in relation to diffusion-controlled release from solid dosage forms. Insoluble matrix formers, such as ethyl cellulose, certain vinyl polymers, starch acetate and others control the permeation of the drug from the preparation and into the surrounding liquid. The rate of mass transfer per area unit is, among other factors, related to the shape of polymeric chains within the dosage form. Higher tortuosity or curviness retards mass transfer as it acts obstructively on the drug particles within the formulation.
HVAC makes extensive use of tortuosity in evaporator and condenser coils for heat exchangers, whereas Ultra-high vacuum makes use of the inverse of tortuosity, which is conductivity, with short, straight, voluminous paths.
Tortuosity has been used in ecology to describe the movement paths of animals.
References
Differential geometry
Porous media
Riemannian geometry
Multivariable calculus
Curves | Tortuosity | Materials_science,Mathematics,Engineering | 1,382 |
3,181,969 | https://en.wikipedia.org/wiki/Fusion%20bonded%20epoxy%20coating | Fusion bonded epoxy coating, also known as fusion-bond epoxy powder coating and commonly referred to as FBE coating, is an epoxy-based powder coating that is widely used to protect steel pipe used in pipeline construction from corrosion. It is also commonly used to protect reinforcing bars (though being phased out as of 2005) and on a wide variety of piping connections, valves etc. FBE coatings are thermoset polymer coatings. They come under the category of protective coatings in paints and coating nomenclature. The name fusion-bond epoxy is due to resigning cross-link and the application method, which is different from a conventional paint. In 2020 the market size was quoted at 12 billion dollars.
The resin and hardener components in the dry powder FBE stock remain unreacted at normal storage conditions. At typical coating application temperatures, usually in the range of , the contents of the powder melt and transform to a liquid form. The liquid FBE film wets and flows onto the steel surface on which it is applied, and soon becomes a solid coating by chemical cross-linking, assisted by heat. This process is known as “fusion bonding”. The chemical cross-linking reaction taking place in this case is irreversible. Once the curing takes place, the coating cannot be returned to its original form by any means. Application of further heating will not “melt” the coating and thus it is known as a “thermoset” coating.
History
Since their introduction as a protective coating in early 1960s, FBE coating formulations had gone through vast improvements and developments. Today, various types of FBE coatings, which are tailor-made to meet various requirements are available. FBEs are available as stand-alone coatings as well as a part in multi-layers. FBE coatings with different properties are available to suit coating application on the main body of pipe, internal surfaces, girth welds as well as on fittings.
Chemistry of FBE coatings
Essential components of a powder coating are:
Resin.
Hardener or curing agent.
Fillers and extenders.
Colour pigments.
The resin and hardener part together is known as the "Binder". As the name indicates, in Fusion bonded epoxy coatings the resin part is an "epoxy" type resin. “Epoxy” or “Oxirane” structure contains a three membered cyclic ring — one oxygen atom connected to two carbon atoms – in the resin molecule. This part is the most reactive group in the epoxy resins. Most commonly used FBE resins are derivatives of bisphenol A and epichlorohydrin.
However, other types of resins (for example bisphenol F type) are also commonly used in FBE formulations to achieve various properties, combinations or additions. Resins are also available in various molecular lengths, to provide unique properties to the final coating.
The second most important part of FBE coatings is the curing agent or hardener. Curing agents react either with the epoxy ring or with the hydroxyl groups, along the epoxy molecular chain. Various types of curing agents, used in FBE manufacture, include dicyandiamide, aromatic amines, aliphatic diamines and organic acid anhydrides. The selected curing agent determines the nature of the final FBE product – its cross linking density, chemical resistance, brittleness, flexibility etc. The ratio of epoxy resins and curing agents in a formulation is determined by their relative equivalent weights.
In addition to these two major components, FBE coatings include fillers, pigments, extenders and various additives, to provide desired properties. These components control characteristics such as permeability, hardness, colour, thickness, gouge resistance etc. All of these components are normally dry solids, even though small quantities of liquid additives may be used in some FBE formulations. If used, these liquid components are sprayed into the formulation mix during pre-blending in the manufacturing process.
The standard for FBE coating of pipelines is ISO 21809 Part 2.
FBE powder manufacturing process
Essential parts of a powder coating manufacturing plant are:
weighting station,
pre-blending station,
an extruder, and
a classifier or grinding unit.
The components of the FBE formulation are weighed and pre-blended in high speed mixers. The mix is then transferred to a high-shear extruder. FBE extruders incorporate a single or dual screw setup, rotating within a fixed clamshell barrel. A temperature range from 50 °C to 100 °C is used within the extruder barrel. This setup compresses the FBE blend, while heating and melting it to a semi-liquid form. During this process, the ingredients of the molten mix are dispersed thoroughly. Because of the fast operation of the extruder and relatively low temperature within the barrel, the epoxy and hardener components will not undergo a significant chemical reaction. The molten extrudate then passes between cold-rollers and becomes a solid, brittle sheet. It then moves to a “Kibbler”, which chops it into smaller chips. These chips are ground, using high speed grinders (classifiers) to a particle size of less than 150 micrometers (standard specifications requires 100% pass through in 250 micrometer sieves and maximum 3% retains in 150 micrometer sieve). The final product is packaged in closed containers, with particular care given to avoid moisture contamination. Normal storage temperatures of FBE powder coatings are below in air-conditioned warehouses.
FBE coating application process
Regardless of the shape and type of steel surface to be coated, the FBE powder coating application has three essential stages:
the steel surface is thoroughly cleaned,
the cleaned metal part is heated to the recommended FBE powder application temperature, and
the application and curing stage.
The advantage of pipe and rebar is that their round shape allows continuous linear application over the exterior surface, while the parts are moved in a conveyor through the powder application booth, ensuring high throughput. On fittings, etc., the coating is applied by manual spray guns. Another method of application is "fluid-dip" process, in which the heated components are dipped in a fluidized powder bed (see below).
Surface preparation—blast cleaning
Blast cleaning is the most commonly used method for preparation of steel surfaces. This effectively removes rust, scale, slats, etc., from the surface and produces an industrial grade cleaning and a rough surface finish. The roughness of the steel achieved after blasting is referred to as profile, which is measured in micrometers or mils. Commonly used to profile ranges for FBE coatings are 37 to 100 micrometers (1.5 to 4 mils). Profile increases the effective surface area of the steel. The cleanliness achieved is assessed to ISO 8501-1 grades: these originated from a set of photographic slides in a Swedish standard (SIS) showing exemplars of the common terminology of white-metal, near white-metal, etc. Typically, SA 2½ is used for pipelines (equivalent to NACE N°2).
It is important to remove grease or oil contamination prior to blast cleaning. Solvent cleaning, burn-off, etc., are commonly used for this purpose. In the blast cleaning process, compressed air (90 to 110 psi/610 to 760 kPa) is used to force an abrasive onto the surface to be cleaned. Aluminum oxide, steel grit, steel shot, garnet, coal slag, etc., are the frequently used abrasives. Another method of blast cleaning is centrifugal blast cleaning, which is especially used in cleaning the exterior of pipe. In this method, abrasive is thrown to the rotating pipe body, using a specially designed wheel, which is rotated at high speed, while the abrasive is fed from the centre of the wheel.
Heating and FBE powder application
Heating can be achieved by using several methods, but the most commonly used ones are ‘’induction heating’’ or ‘’oven heating’’. The steel part is passed through a high frequency alternating current magnetic field, which heats the metal part to the required FBE coating application temperature. Typical application temperature for a stand alone FBE is 225° to 245°C. When used as a primer in a multi-layer polyolifine system, application temperature may be dropped based on FBE manufacturer's recommendations, in order to meet the "inter-coat adhesion" parameters. Special grade FBE coatings which can be applied at temperatures as low as 175 °C has been developed recently by certain FBE powder manufacturers. Other methods of heating are ‘’oven heating’’, ‘’infra-red heating’’, etc. The FBE powder is placed on a “fluidization bed”. In a fluidization bed, the powder particles are suspended in a stream of air, in which the powder will “behave” like a fluid. Once the air supply is turned off, the powder will remain in its original form. The fluidized powder is sprayed onto the hot substrate using suitable spray guns. An electrostatic spray gun incorporates an ionizer electrode on it, which gives the powder particles a positive electric charge. The steel to be coated is “grounded” through the conveyor. The charged powder particles uniformly wraps around the substrate, and melts into a liquid form. Internal surfaces of pipes are coated using spraying lances, which travel from one end to the other end of the heated pipe at a uniform speed, while the pipe is being rotated in its longitudinal axis.
Standard coating thickness range of stand-alone FBE coatings is between 250 and 500 micrometers, even though lower or higher thickness ranges might be specified, depending on service conditions. The molten powder ‘flows’ into the profile and bonds with the steel. The molten powder will become a solid coating, when the ‘gel time’ is over, which usually occurs within few seconds after coating application. The resin part of coating will undergo cross-linking, which is known as “curing” under the hot condition. Complete curing is achieved either by the residual heat on the steel, or by the help of additional heating sources. Depending on the FBE coating system, full cure can be achieved in less than one minute to few minutes in case of long cure FBE's, which are used for internal pipe coating applications.
Rebars are coated in a similar manner as coating application, on the exterior of pipes. For FBE coating application on the interior of pipe surface, a lance is used. The lance enters into the pre-heated pipe, and starts spraying the powder from the opposite end, while the pipe is being rotated on its axis and the lance pulls out in a pre-determined speed.
On fittings such as Tee's, elbows, bends, etc., powder can be sprayed using hand held spray guns. Small sized fittings can also be coated by dipping in a fluidized bed of powder, after heating the steel to the required powder application temperature. After field welding of the pipe ends, FBE can be applied on the weld area as well.
Advantages of FBE application over conventional liquid coating application are:
Ease of application,
Less waste of material,
Rapid application,
Cure schedules, which means faster production rates
Failures
There are a number of potential failure modes for Fusion bonded epoxy. One of these failure modes is by ultraviolet degradation.
Manufacturers
The world's leading FBE manufacturers are Sherwin-Williams (Valspar), SolEpoxy (former Henkel/Dexter), KCC Corporation, Jotun Powder Coatings, 3M, Axalta Coating Systems, Akzo Nobel, BASF, and Rohm & Haas.
See also
Cathodic protection
Corrosion
DCVG
Epoxy
Powder coating
Rebar
Thermoset powder coatings
References
Further reading
External links
Improving Functional Powder Coatings' Corrosion Protection
Epoxy Interest Group of CRSI - Reinforcing Steel Coating
Corrosion protection by coatings for water and wastewater pipelines
Laboratory Evaluation of Fusion-Bonded Epoxy Coatings for Civil Works Applications
Coatings | Fusion bonded epoxy coating | Chemistry | 2,525 |
43,333 | https://en.wikipedia.org/wiki/Measurable%20space | In mathematics, a measurable space or Borel space is a basic object in measure theory. It consists of a set and a σ-algebra, which defines the subsets that will be measured.
It captures and generalises intuitive notions such as length, area, and volume with a set of 'points' in the space, but regions of the space are the elements of the σ-algebra, since the intuitive measures are not usually defined for points. The algebra also captures the relationships that might be expected of regions: that a region can be defined as an intersection of other regions, a union of other regions, or the space with the exception of another region.
Definition
Consider a set and a σ-algebra on Then the tuple is called a measurable space. The elements of are called measurable sets within the measurable space.
Note that in contrast to a measure space, no measure is needed for a measurable space.
Example
Look at the set:
One possible -algebra would be:
Then is a measurable space. Another possible -algebra would be the power set on :
With this, a second measurable space on the set is given by
Common measurable spaces
If is finite or countably infinite, the -algebra is most often the power set on so This leads to the measurable space
If is a topological space, the -algebra is most commonly the Borel -algebra so This leads to the measurable space that is common for all topological spaces such as the real numbers
Ambiguity with Borel spaces
The term Borel space is used for different types of measurable spaces. It can refer to
any measurable space, so it is a synonym for a measurable space as defined above
a measurable space that is Borel isomorphic to a measurable subset of the real numbers (again with the Borel -algebra)
See also
Category of measurable spaces
References
Measure theory
Space (mathematics) | Measurable space | Mathematics | 385 |
11,241,001 | https://en.wikipedia.org/wiki/Quantum%20master%20equation | A quantum master equation is a generalization of the idea of a master equation. Rather than just a system of differential equations for a set of probabilities (which only constitutes the diagonal elements of a density matrix), quantum master equations are differential equations for the entire density matrix, including off-diagonal elements. A density matrix with only diagonal elements can be modeled as a classical random process, therefore such an "ordinary" master equation is considered classical. Off-diagonal elements represent quantum coherence which is a physical characteristic that is intrinsically quantum mechanical.
A formally exact quantum master equation is the Nakajima–Zwanzig equation, which is in general as difficult to solve as the full quantum problem.
The Redfield equation and Lindblad equation are examples of approximate Markovian quantum master equations. These equations are very easy to solve, but are not generally accurate.
Some modern approximations based on quantum master equations, which show better agreement with exact numerical calculations in some cases, include the polaron transformed quantum master equation and the VPQME (variational polaron transformed quantum master equation).
Numerically exact approaches to the kinds of problems to which master equations are usually applied include numerical Feynman integrals, quantum Monte Carlo, DMRG and NRG, MCTDH, and HEOM.
See also
Open quantum system
Quantum dynamics
Quantum coherence
Differential equation
Master equation
Lindblad equation
Nakajima–Zwanzig equation
Feynman integral
References
Equations | Quantum master equation | Mathematics | 301 |
12,932,617 | https://en.wikipedia.org/wiki/Halobaculum | Halobaculum (common abbreviation: Hbl.) is a genus of the Halorubraceae.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).
Unassigned species:
H. halobium Tan et al. 2024
H. limi Tan et al. 2024
H. lipolyticum Tan et al. 2024
H. litoreum Tan et al. 2024
H. marinum Tan et al. 2024
See also
List of Archaea genera
References
Further reading
Scientific journals
Scientific books
Archaea genera
Taxa described in 1995 | Halobaculum | Biology | 143 |
2,702,982 | https://en.wikipedia.org/wiki/Topological%20tensor%20product | In mathematics, there are usually many different ways to construct a topological tensor product of two topological vector spaces. For Hilbert spaces or nuclear spaces there is a simple well-behaved theory of tensor products (see Tensor product of Hilbert spaces), but for general Banach spaces or locally convex topological vector spaces the theory is notoriously subtle.
Motivation
One of the original motivations for topological tensor products is the fact that tensor products of the spaces of smooth real-valued functions on do not behave as expected. There is an injection
but this is not an isomorphism. For example, the function cannot be expressed as a finite linear combination of smooth functions in We only get an isomorphism after constructing the topological tensor product; i.e.,
This article first details the construction in the Banach space case. The space is not a Banach space and further cases are discussed at the end.
Tensor products of Hilbert spaces
The algebraic tensor product of two Hilbert spaces A and B has a natural positive definite sesquilinear form (scalar product) induced by the sesquilinear forms of A and B. So in particular it has a natural positive definite quadratic form, and the corresponding completion is a Hilbert space A ⊗ B, called the (Hilbert space) tensor product of A and B.
If the vectors ai and bj run through orthonormal bases of A and B, then the vectors ai⊗bj form an orthonormal basis of A ⊗ B.
Cross norms and tensor products of Banach spaces
We shall use the notation from in this section. The obvious way to define the tensor product of two Banach spaces and is to copy the method for Hilbert spaces: define a norm on the algebraic tensor product, then take the completion in this norm. The problem is that there is more than one natural way to define a norm on the tensor product.
If and are Banach spaces the algebraic tensor product of and means the tensor product of and as vector spaces and is denoted by The algebraic tensor product consists of all finite sums
where is a natural number depending on and and for
When and are Banach spaces, a (or ) on the algebraic tensor product is a norm satisfying the conditions
Here and are elements of the topological dual spaces of and respectively, and is the dual norm of The term is also used for the definition above.
There is a cross norm called the projective cross norm, given by
where
It turns out that the projective cross norm agrees with the largest cross norm (, pp. 15-16).
There is a cross norm called the injective cross norm, given by
where Here and denote the topological duals of and respectively.
Note hereby that the injective cross norm is only in some reasonable sense the "smallest".
The completions of the algebraic tensor product in these two norms are called the projective and injective tensor products, and are denoted by and
When and are Hilbert spaces, the norm used for their Hilbert space tensor product is not equal to either of these norms in general. Some authors denote it by so the Hilbert space tensor product in the section above would be
A is an assignment to each pair of Banach spaces of a reasonable crossnorm on so that if are arbitrary Banach spaces then for all (continuous linear) operators and the operator is continuous and If and are two Banach spaces and is a uniform cross norm then defines a reasonable cross norm on the algebraic tensor product The normed linear space obtained by equipping with that norm is denoted by The completion of which is a Banach space, is denoted by The value of the norm given by on and on the completed tensor product for an element in (or ) is denoted by
A uniform crossnorm is said to be if, for every pair of Banach spaces and every
A uniform crossnorm is if, for every pair of Banach spaces and every
A is defined to be a finitely generated uniform crossnorm. The projective cross norm and the injective cross norm defined above are tensor norms and they are called the projective tensor norm and the injective tensor norm, respectively.
If and are arbitrary Banach spaces and is an arbitrary uniform cross norm then
Tensor products of locally convex topological vector spaces
The topologies of locally convex topological vector spaces and are given by families of seminorms. For each choice of seminorm on and on we can define the corresponding family of cross norms on the algebraic tensor product and by choosing one cross norm from each family we get some cross norms on defining a topology. There are in general an enormous number of ways to do this. The two most important ways are to take all the projective cross norms, or all the injective cross norms. The completions of the resulting topologies on are called the projective and injective tensor products, and denoted by and There is a natural map from to
If or is a nuclear space then the natural map from to is an isomorphism. Roughly speaking, this means that if or is nuclear, then there is only one sensible tensor product of and .
This property characterizes nuclear spaces.
See also
References
.
.
Operator theory
Topological vector spaces
Hilbert spaces
Tensors | Topological tensor product | Physics,Mathematics,Engineering | 1,046 |
18,062,676 | https://en.wikipedia.org/wiki/Monogenic%20field | In mathematics, a monogenic field is an algebraic number field K for which there exists an element a such that the ring of integers OK is the subring Z[a] of K generated by a. Then OK is a quotient of the polynomial ring Z[X] and the powers of a constitute a power integral basis.
In a monogenic field K, the field discriminant of K is equal to the discriminant of the minimal polynomial of α.
Examples
Examples of monogenic fields include:
Quadratic fields:
if with a square-free integer, then where if d ≡ 1 (mod 4) and if d ≡ 2 or 3 (mod 4).
Cyclotomic fields:
if with a root of unity, then Also the maximal real subfield is monogenic, with ring of integers .
While all quadratic fields are monogenic, already among cubic fields there are many that are not monogenic. The first example of a non-monogenic number field that was found is the cubic field generated by a root of the polynomial , due to Richard Dedekind.
References
Algebraic number theory | Monogenic field | Mathematics | 229 |
56,431,248 | https://en.wikipedia.org/wiki/Ana%20Mijic | Ana Mijic is an associate professor in the Department of Civil Engineering at Imperial College London who works in systems water management. She has expertise in advanced modelling of integrated water systems, as well as the analysis of processes, planning, resilience and economics.
Education
Mijic completed an MEng degree in civil engineering at the University of Belgrade, Serbia. She moved to Imperial College London and earned a master's degree in hydrology for environmental management, in 2009 with distinction. She received her PhD from Imperial College London in 2013, for "Near-well effects in carbon dioxide storage in saline aquifers". Mijic was described by the Royal Meteorological Society as an "influential voice" in 2017.
Research
After completing her PhD, Mijic remained at Imperial working on the Joint UK Land Environment Simulator (JULES). Since, she has been involved with a number of large scale international hydrological studies and surveys. In 2014 she was co-investigator on a NERC British Geological Survey funded project "Assessing the risk of groundwater-induced sewer flooding to inform water and sewerage company investment planning" alongside Chris Jackson. That year she led "Improved techno-economic evaluation of Blue Green Solutions for managing flood risk to infrastructure", also funded by NERC. She was co-investigator on FLIRE, an integrated decision support system for risk assessment of flash floods and forest fires. Mijic works with Imperial College London's Grantham Institute for Climate Change on Blue Green Dream, a systems approach to sustainable, cost-efficient urban development. She also works on "Hydroflux India", which monitors changes in water storage and fluxes in Northern India. She has also investigated pluvial floods in mediterranean cities.
Mijic is an affiliate of the Grantham Institute for Climate Change. In 2017, Mijic was promoted to senior lecturer at Imperial College London. Her research themes focus on:
Data collection and simulations of inclusive water management zones
Refining developed methods to improve planning and decision making of integrated water management
Providing inputs for land surface-atmosphere coupling and urban micro-climate simulations
Mijic has three children and has spoken about how the support of Imperial College London allowed her to balance a scientific career and being a mother.
Awards
2015 – Business Green Technology Award 2015 for the Blue Green Dream R&D Programme of the Year
2011 – ORSAS (Overseas Research Students Awards Scheme) Award, The Department of Earth Science and Engineering, Imperial College London
2010 – John Archer Scholarship Award, The Department of Earth Science and Engineering, Imperial College London
2009 – Victor Appleby Prize in Engineering Hydrology, Imperial College London
2009 – The Letitia Chitty Centenary Memorial Prize, Imperial College London
References
Living people
University of Belgrade Faculty of Civil Engineering alumni
Alumni of Imperial College London
Academics of Imperial College London
Hydrologists
Year of birth missing (living people)
Women hydrologists | Ana Mijic | Environmental_science | 567 |
36,685,860 | https://en.wikipedia.org/wiki/C14H14N2 | {{DISPLAYTITLE:C14H14N2}}
The molecular formula C14H14N2 (molar mass: 210.27 g/mol, exact mass: 210.1157 u) may refer to:
3-Amino-9-ethylcarbazole (AEC)
Naphazoline | C14H14N2 | Chemistry | 71 |
1,706,275 | https://en.wikipedia.org/wiki/Raney%20nickel | Raney nickel , also known as the primary catalyst for the Cormas-Grisius Electrophilic Benzene Addition, is a fine-grained solid composed mostly of nickel derived from a nickel–aluminium alloy. Several grades are known, of which most are gray solids. Some are pyrophoric, but most are used as air-stable slurries. Raney nickel is used as a reagent and as a catalyst in organic chemistry. It was developed in 1926 by American engineer Murray Raney for the hydrogenation of vegetable oils.
Raney Nickel is a registered trademark of W. R. Grace and Company. Other major producers are Evonik and Johnson Matthey.
Preparation
Alloy preparation
The Ni–Al alloy is prepared by dissolving nickel in molten aluminium followed by cooling ("quenching"). Depending on the Ni:Al ratio, quenching produces a number of different phases.
During the quenching procedure, small amounts of a third metal, such as zinc or chromium, are added to enhance the activity of the resulting catalyst. This third metal is called a "promoter". The promoter changes the mixture from a binary alloy to a ternary alloy, which can lead to different quenching and leaching properties during activation.
Activation
In the activation process, the alloy, usually as a fine powder, is treated with a concentrated solution of sodium hydroxide. The simplified leaching reaction is given by the following chemical equation:
2 Al + 2 NaOH + 6 H2O → 2 Na[Al(OH)4] + 3 H2
The formation of sodium aluminate (Na[Al(OH)4]) requires that solutions of high concentration of sodium hydroxide be used to avoid the formation of aluminium hydroxide, which otherwise would precipitate as bayerite. Hence sodium hydroxide solutions with concentrations of up to 5 M are used.
The temperature used to leach the alloy has a marked effect on the properties of the catalyst. Commonly, leaching is conducted between 70 and 100 °C. The surface area of Raney nickel (and related catalysts in general) tends to decrease with increasing leaching temperature. This is due to structural rearrangements within the alloy that may be considered analogous to sintering, where alloy ligaments would start adhering to each other at higher temperatures, leading to the loss of the porous structure.
During the activation process, Al is leached out of the NiAl3 and Ni2Al3 phases that are present in the alloy, while most of the Ni remains, in the form of NiAl. The removal of Al from some phases but not others is known as "selective leaching". The NiAl phase has been shown to provide the structural and thermal stability of the catalyst. As a result, the catalyst is quite resistant to decomposition ("breaking down", commonly known as "aging"). This resistance allows Raney nickel to be stored and reused for an extended period; however, fresh preparations are usually preferred for laboratory use. For this reason, commercial Raney nickel is available in both "active" and "inactive" forms.
Before storage, the catalyst can be washed with distilled water at ambient temperature to remove remaining sodium aluminate. Oxygen-free (degassed) water is preferred for storage to prevent oxidation of the catalyst, which would accelerate its aging process and result in reduced catalytic activity.
Properties
Macroscopically, Raney nickel is a finely divided, grey powder. Microscopically, each particle of this powder is a three-dimensional mesh, with pores of irregular size and shape, the vast majority of which are created during the leaching process. Raney nickel is notable for being thermally and structurally stable, as well as having a large Brunauer-Emmett-Teller (BET ) surface area. These properties are a direct result of the activation process and contribute to a relatively high catalytic activity.
The surface area is typically determined by a BET measurement using a gas that is preferentially adsorbed on metallic surfaces, such as hydrogen. Using this type of measurement, almost all the exposed area in a particle of the catalyst has been shown to have Ni on its surface. Since Ni is the active metal of the catalyst, a large Ni surface area implies a large surface is available for reactions to occur simultaneously, which is reflected in an increased catalyst activity. Commercially available Raney nickel has an average Ni surface area of 100 m2 per gram of catalyst.
A high catalytic activity, coupled with the fact that hydrogen is absorbed within the pores of the catalyst during activation, makes Raney nickel a useful catalyst for many hydrogenation reactions. Its structural and thermal stability (i.e., it does not decompose at high temperatures) allows its use under a wide range of reaction conditions. Additionally, the solubility of Raney nickel is negligible in most common laboratory solvents, with the exception of mineral acids such as hydrochloric acid, and its relatively high density (about 6.5 g cm−3) also facilitates its separation from a liquid phase after a reaction is completed.
Applications
Raney nickel is used in a large number of industrial processes and in organic synthesis because of its stability and high catalytic activity at room temperature.
Industrial applications
In a commercial application, Raney nickel is used as a catalyst for the hydrogenation of benzene to cyclohexane. Other heterogeneous catalysts, such as those using platinum group elements are used in some cases. Platinum metals tend to be more active, requiring milder temperatures, but they are more expensive than Raney nickel. The cyclohexane thus produced may be used in the synthesis of adipic acid, a raw material used in the industrial production of polyamides such as nylon.
Other industrial applications of Raney nickel include the conversion of:
Dextrose to sorbitol;
Nitro compounds to amines, for example, 2,4-dinitrotoluene to 2,4-toluenediamine;
Nitriles to amines, for example, stearonitrile to stearylamine and adiponitrile to hexamethylenediamine;
Olefins to paraffins, for example, sulfolene to sulfolane;
Acetylenes to paraffins, for example, 1,4-butynediol to 1,4-butanediol.
Applications in organic synthesis
Desulfurization
Raney nickel is used in organic synthesis for desulfurization. For example, thioacetals will be reduced to hydrocarbons in the last step of the Mozingo reduction:
Thiols, and sulfides can be removed from aliphatic, aromatic, or heteroaromatic compounds. Likewise, Raney nickel will remove the sulfur of thiophene to give a saturated alkane.
Reduction of functional groups
It is typically used in the reduction of compounds with multiple bonds, such as alkynes, alkenes, nitriles, dienes, aromatics and carbonyl-containing compounds. Additionally, Raney nickel will reduce heteroatom-heteroatom bonds, such as hydrazines, nitro groups, and nitrosamines. It has also found use in the reductive alkylation of amines and the amination of alcohols.
When reducing a carbon-carbon double bond, Raney nickel will add hydrogen in a syn fashion.
Related catalysts
Raney cobalt has also been described.
In contrast to the pyrophoric nature of some forms of Raney nickel, nickel silicide-based catalysts represent potentially safer alternatives.
Raney alloys include FeTi and other non Nickel alloys. FeTi has been considered for low pressure Hydrogen Storage. Aldricimica Acta (free from Sigma nee Aldrich) has a complete list of Raney alloys.
Safety
Due to its large surface area and high volume of contained hydrogen gas, dry, activated Raney nickel is a pyrophoric material that requires handling under an inert atmosphere. Raney nickel is typically supplied as a 50% slurry in water. Even after reaction, residual Raney nickel contains significant amounts of hydrogen gas and may spontaneously ignite when exposed to air.
Additionally, acute exposure to Raney nickel may cause irritation of the respiratory tract and nasal cavities, and causes pulmonary fibrosis if inhaled. Ingestion may lead to convulsions and intestinal disorders. It can also cause eye and skin irritation. Chronic exposure may lead to pneumonitis and other signs of sensitization to nickel, such as skin rashes ("nickel itch").
Nickel is also rated as being a possible human carcinogen by the IARC (Group 2B, EU category 3) and teratogen, while the inhalation of fine aluminium oxide particles is associated with Shaver's disease.
Development
Murray Raney graduated as a mechanical engineer from the University of Kentucky in 1909. In 1915 he joined the Lookout Oil and Refining Company in Tennessee and was responsible for the installation of electrolytic cells for the production of hydrogen which was used in the hydrogenation of vegetable oils. During that time the industry used a nickel catalyst prepared from nickel(II) oxide. Believing that better catalysts could be produced, around 1921 he started to perform independent research while still working for Lookout Oil. In 1924 a 1:1 ratio Ni/Si alloy was produced, which after treatment with sodium hydroxide, was found to be five times more active than the best catalyst used in the hydrogenation of cottonseed oil. A patent for this discovery was issued in December 1925.
Subsequently, Raney produced a 1:1 Ni/Al alloy following a procedure similar to the one used for the nickel-silicon catalyst. He found that the resulting catalyst was even more active and filed a patent application in 1926. This is now a common alloy composition for modern Raney nickel catalysts. Other common alloy compositions include 21:29 Ni/Al and 3:7 Ni/Al. Both the activity and preparation protocols for these catalysts vary.
Following the development of Raney nickel, other alloy systems with aluminium were considered, of which the most notable include copper, ruthenium and cobalt. Further research showed that adding a small amount of a third metal to the binary alloy would promote the activity of the catalyst. Some widely used promoters are zinc, molybdenum and chromium. An alternative way of preparing enantioselective Raney nickel has been devised by surface adsorption of tartaric acid.
See also
Nickel aluminide
Urushibara nickel
Rieke nickel
Nickel boride catalyst
Raney cobalt, a similar cobalt/aluminum alloy catalyst which is sometimes more selective for certain hydrogenation products (e.g. primary amines via nitrile reduction).
References
External links
International Chemical Safety Card 0062
NIOSH Pocket Guide to Chemical Hazards
1941 paper describing the preparation of W-2 grade Raney nickel:
Catalysts
Nickel alloys
Hydrogenation catalysts
Pyrophoric materials | Raney nickel | Chemistry,Technology | 2,282 |
53,763,419 | https://en.wikipedia.org/wiki/Amable%20Li%C3%B1%C3%A1n | Amable Liñán Martínez (born 1934 in Noceda de Cabrera, Castrillo de Cabrera, León, Spain) is a Spanish aeronautical engineer working in the field of combustion.
Biography
He holds a PhD in Aeronautical Engineering from the Technical University of Madrid, advised by Gregorio Millán Barbany and Degree of Aeronautical Engineer from the Caltech advised by Frank E. Marble.
He is currently Professor of Fluid Mechanics and professor emeritus at the Higher Technical School of Aeronautical Engineers of the Polytechnic University of Madrid (attached to the Department of Motorcycle and Thermofluidodynamics of said school). He has taught at universities in California, Michigan and Princeton University in the United States and in Marseilles in France, among others. Since 1997 he is an adjunct professor at Yale University.
Research
He has focused his research studies on the basic problems of combustion, both reactor and planetary probe dynamics, in the latter case working directly for NASA and the European Space Agency.
The diffusion flame structure in counterflow wa analyzed by him in 1974 through activation-energy asymptotics.
Publications
He is the author of several books and scientific research.
Honors
In 1989 he was elected member of the Royal Academy of Exact, Physical and Natural Sciences. He is also a member of the Royal Academy of Engineering of Spain, France and Mexico. He is also a member of the scientific board of the IMDEA Energy Institute. He is also an elected foreign member of National Academy of Engineering for discoveries using asymptotic analyses in combustion and for contributions to advance engineering science. In 2007 he received the "Miguel Catalán" Research Award from the Community of Madrid and was awarded in 1993 with the Prince of Asturias Award for Scientific and Technical Research. A workshop in honor of Liñán's work was conducted in 2004 and the workshop papers are published in a book titled Simplicity, rigor and relevance in fluid mechanics : a volume in honor of Amable Liñán, CIMNE, (2004).
See also
References
External links
Spanish engineers
Fluid dynamicists
1934 births
Living people
California Institute of Technology alumni
Members of the United States National Academy of Engineering
Fellows of the Combustion Institute | Amable Liñán | Chemistry | 435 |
13,478,962 | https://en.wikipedia.org/wiki/Cultural%20algorithm | Cultural algorithms (CA) are a branch of evolutionary computation where there is a knowledge component that is called the belief space in addition to the population component. In this sense, cultural algorithms can be seen as an extension to a conventional genetic algorithm. Cultural algorithms were introduced by Reynolds (see references).
Belief space
The belief space of a cultural algorithm is divided into distinct categories. These categories represent different domains of knowledge that the population has of the search space.
The belief space is updated after each iteration by the best individuals of the population. The best individuals can be selected using a fitness function that assesses the performance of each individual in population much like in genetic algorithms.
List of belief space categories
Normative knowledge A collection of desirable value ranges for the individuals in the population component e.g. acceptable behavior for the agents in population.
Domain specific knowledge Information about the domain of the cultural algorithm problem is applied to.
Situational knowledge Specific examples of important events - e.g. successful/unsuccessful solutions
Temporal knowledge History of the search space - e.g. the temporal patterns of the search process
Spatial knowledge Information about the topography of the search space
Population
The population component of the cultural algorithm is approximately the same as that of the genetic algorithm.
Communication protocol
Cultural algorithms require an interface between the population and belief space. The best individuals of the population can update the belief space via the update function. Also, the knowledge categories of the belief space can affect the population component via the influence function. The influence function can affect population by altering the genome or the actions of the individuals.
Pseudocode for cultural algorithms
Initialize population space (choose initial population)
Initialize belief space (e.g. set domain specific knowledge and normative value-ranges)
Repeat until termination condition is met
Perform actions of the individuals in population space
Evaluate each individual by using the fitness function
Select the parents to reproduce a new generation of offspring
Let the belief space alter the genome of the offspring by using the influence function
Update the belief space by using the accept function (this is done by letting the best individuals to affect the belief space)
Applications
Various optimization problems
Social simulation
Real-parameter optimization
See also
Artificial intelligence
Artificial life
Evolutionary computation
Genetic algorithm
Harmony search
Machine learning
Memetic algorithm
Memetics
Metaheuristic
Social simulation
Sociocultural evolution
Stochastic optimization
Swarm intelligence
References
Robert G. Reynolds, Ziad Kobti, Tim Kohler: Agent-Based Modeling of Cultural Change in Swarm Using Cultural Algorithms
R. G. Reynolds, “An Introduction to Cultural Algorithms, ” in Proceedings of the 3rd Annual Conference on Evolutionary Programming, World Scientific Publishing, pp 131–139, 1994.
Robert G. Reynolds, Bin Peng. Knowledge Learning and Social Swarms in Cultural Systems. Journal of Mathematical Sociology. 29:1-18, 2005
Reynolds, R. G., and Ali, M. Z, “Embedding a Social Fabric Component into Cultural Algorithms Toolkit for an Enhanced Knowledge-Driven Engineering Optimization”, International Journal of Intelligent Computing and Cybernetics (IJICC), Vol. 1, No 4, pp. 356–378, 2008
Reynolds, R G., and Ali, M Z., Exploring Knowledge and Population Swarms via an Agent-Based Cultural Algorithms Simulation Toolkit (CAT), in proceedings of IEEE Congress on Computational Intelligence 2007.
Evolutionary algorithms
Genetic algorithms
Nature-inspired metaheuristics | Cultural algorithm | Biology | 681 |
19,008,450 | https://en.wikipedia.org/wiki/Prison | A prison, also known as a jail, gaol, penitentiary, detention center, correction center, correctional facility, remand center, hoosegow, or slammer, is a facility where people are imprisoned under the authority of the state, usually as punishment for various crimes. Prisons are most commonly used within a criminal-justice system by authorities: people charged with crimes may be imprisoned until their trial; those who have pleaded or been found guilty of crimes at trial may be sentenced to a specified period of imprisonment.
Prisons can also be used as a tool for political repression by authoritarian regimes who detain perceived opponents for political crimes, often without a fair trial or due process; this use is illegal under most forms of international law governing fair administration of justice. In times of war, belligerents or neutral countries may detain prisoners of war or detainees in military prisons or in prisoner-of-war camps. At any time, states may imprison civilians – sometimes large groups of civilians – in internment camps.
Naming
United States
In American English, the terms prison and jail have separate definitions, though this is not always adhered to in casual speech.
A jail holds people for shorter periods of time or for pre-trial detention and is usually operated by a local government, typically the county sheriff.
A prison or penitentiary holds people for longer periods of time, such as many years, and is operated by a state or federal government. After a conviction, a sentenced person is sent to prison.
Outside of the United States, prison and jail often have the same meaning.
New Zealand
In New Zealand, the terms "jail" and "prison" are commonly used, although the terms "correctional facility" and "prison" among others are in official usage.
Papua New Guinea
In Papua New Guinea, "prison" is officially used, although "jail" is widely understood and more common in usage.
Australia
In Australia, the words "gaol", "jail" and "prison" are commonly used. The spelling "gaol" was in official use in the past, and many historical gaols are now tourist attractions, such as the Maitland Gaol. Officially, the term "correctional centre" is used for almost all prisons in New South Wales and Queensland, while other states and territories use a variety of names. "Prison" is officially used for some facilities in South Australia, Victoria and Western Australia. Youth prisons in Australia are referred to as "youth correctional facilities" or "youth detention centres" among other names, depending on the jurisdiction.
Canada
In Canada, while the terms "jail" and "prison" are commonly used in speech, officially named facilities use "facility", "correctional centre", "penitentiary", or "institution". A number of facilities retain their historical designation as a "jail".
History
Ancient and medieval
The use of prisons can be traced back to the rise of the state as a form of social organization.
Some Ancient Greek philosophers, such as Plato, began to develop ideas of using punishment to reform offenders instead of for retribution. Imprisonment as a penalty was used commonly for those who could not afford to pay their fines. Eventually, since impoverished Athenians could not pay their fines, leading to indefinite periods of imprisonment, time limits were set instead. The prison in ancient Athens was known as the desmoterion or "the place of chains".
The Romans were among the first to use prisons as a form of punishment rather than simply for detention. A variety of existing structures were used to house prisoners, such as metal cages, basements of public buildings, and quarries. One of the most notable Roman prisons was the Mamertine Prison, established around 640 B.C. by Ancus Marcius. The Mamertine Prison was located within a sewer system beneath ancient Rome and contained a large network of dungeons where prisoners were held in squalid conditions contaminated with human waste. Forced labor on public works projects was also a common form of punishment. In many cases, citizens were sentenced to slavery, often in ergastula (a primitive form of prison where unruly slaves were chained to workbenches and performed hard labor). There were numerous prisons not only in the capital Rome, but throughout the Roman Empire. However, a regulated prison system did not emerge.
In Medieval Songhai, results of a trial could have led to confiscation of merchandise or imprisonment as a form of punishment, since various prisons existed in the empire.
During the Middle Ages in Europe, castles, fortresses, and the basements of public buildings were often used as makeshift prisons. The capability to imprison citizens granted an air of legitimacy to officials at all levels of government and served as a signifier of who possessed power or authority over others. Another common punishment was sentencing people to galley slavery, which involved chaining prisoners together in the bottoms of ships and forcing them to row on naval or merchant vessels.
Modern era
The French philosopher Michel Foucault, especially his book Discipline and Punish: The Birth of the Prison (1975), energized the historical study of prisons and their role in the overall social system. The book analyzed changes in Western penal systems during the modern age based on historical documents from France. Foucault argues that prison did not become the principal form of punishment just because of the humanitarian concerns of reformists. He traces the cultural shifts that led to the predominance of prison via the body and power. Prison used by the "disciplines" – new technological powers that can be found, according to Foucault, in places such as schools, hospitals, and military barracks.
From the late 17th century and during the 18th century, popular resistance to public execution and torture became more widespread both in Europe and in the United States. Particularly under the Bloody Code, with few sentencing alternatives, imposition of the death penalty for petty crimes, such as theft, was proving increasingly unpopular with the public; many jurors were refusing to convict defendants of petty crimes when they knew the defendants would be sentenced to death. Rulers began looking for means to punish and control their subjects in a way that did not cause people to associate them with spectacles of tyrannical and sadistic violence. They developed systems of mass incarceration, often with hard labor, as a solution. The prison reform movement that arose at this time was heavily influenced by two somewhat contradictory philosophies. The first was based in Enlightenment ideas of utilitarianism and rationalism, and suggested that prisons should simply be used as a more effective substitute for public corporal punishments such as whipping, hanging, etc. This theory, referred to as deterrence, claims that the primary purpose of prisons is to be so harsh and terrifying that they deter people from committing crimes out of fear of going to prison. The second theory, which saw prisons as a form of rehabilitation or moral reform, was based on religious ideas that equated crime with sin, and saw prisons as a place to instruct prisoners in Christian morality, obedience and proper behavior. These later reformers believed that prisons could be constructed as humane institutions of moral instruction, and that prisoners' behavior could be "corrected" so that when they were released, they would be model members of society.
The concept of the modern prison was imported to Europe in the early 19th-century.[from where?] Prior forms of punishment were usually physical, including capital punishment, mutilation, flagellation (whipping), branding, and non-physical punishments, such as public shaming rituals (like the stocks). From the Middle Ages up to the 16th and 17th centuries in Europe, imprisonment was rarely used as a punishment in its own right, and prisons were mainly to hold those awaiting trial or punishment.
However, an important innovation at the time was the Bridewell House of Corrections, located at Bridewell Palace in London, which resulted in the building of other houses of correction. These houses held mostly petty offenders, vagrants, and the disorderly local poor. In these facilities, the inmates were given "prison labor" jobs that were anticipated to shape them into hardworking individuals and prepare them for the real world. By the end of the 17th century, houses of correction were absorbed into local prison facilities under the control of the local justice of the peace.
Transportation, prison ships and penal colonies
England used penal transportation of convicted criminals (and others generally young and poor) for a term of indentured servitude within the general population of British America between the 1610s and 1776. The Transportation Act 1717 made this option available for lesser crimes, or offered it by discretion as a longer-term alternative to the death penalty, which could theoretically be imposed for the growing number of offenses in Britain. The substantial expansion of transportation was the first major innovation in eighteenth-century British penal practice. Transportation to America was abruptly suspended by the Criminal Law Act 1776 (16 Geo. 3. c. 43) with the start of the American Rebellion. While sentencing to transportation continued, the act instituted a punishment policy of hard labor instead. The suspension of transport also prompted the use of prisons for punishment and the initial start of a prison building program. Britain would resume transportation to specifically planned penal colonies in Australia between 1788 and 1868.
Jails at the time were run as business ventures, and contained both felons and debtors; the latter were often housed with their wives and younger children. The jailers made their money by charging the inmates for food, drink, and other services, and the system was generally corruptible. One reform of the seventeenth century was the establishment of the London Bridewell as a house of correction for women and children. It was the first facility to make any medical services available to prisoners.
With the widely used alternative of penal transportation halted in the 1770s, the immediate need for additional penal accommodations emerged. Given the undeveloped institutional facilities, old sailing vessels, termed hulks, were the most readily available and expandable choice to be used as places of temporary confinement. While conditions on these ships were generally appalling, their use and the labor thus provided set a precedent which persuaded many people that mass incarceration and labor were viable methods of crime prevention and punishment. The turn of the 19th century would see the first movement toward prison reform, and by the 1810s, the first state prisons and correctional facilities were built, thereby inaugurating the modern prison facilities available today.
France also sent criminals to overseas penal colonies, including Louisiana, in the early 18th century. Penal colonies in French Guiana operated until 1952, such as the notable Devil's Island (Île du Diable). Katorga prisons were harsh work camps established in the 17th century in Russia, in remote underpopulated areas of Siberia and the Russian Far East, that had few towns or food sources. Siberia quickly gained its fearful connotation of punishment.
Prison reform movement
John Howard was one of the most notable early prison reformers. After having visited several hundred prisons across Great Britain and Europe, in his capacity as high sheriff of Bedfordshire, he published The State of the Prisons in 1777. He was particularly appalled to discover prisoners who had been acquitted but were still confined because they could not pay the jailer's fees. He proposed wide-ranging reforms to the system, including the housing of each prisoner in a separate cell and the requirements that staff should be professional and paid by the government, that outside inspection of prisons should be imposed, and that prisoners should be provided with a healthy diet and reasonable living conditions. The prison reform charity, the Howard League for Penal Reform, was established in 1866 by his admirers.
Following Howard's agitation, the Penitentiary Act 1799 was passed. This introduced solitary confinement, religious instruction, a labor regime, and proposed two state penitentiaries (one for men and one for women). However, these were never built due to disagreements in the committee and pressures from wars with France, and jails remained a local responsibility. But other measures passed in the next few years provided magistrates with the powers to implement many of these reforms, and eventually, in 1815, jail fees were abolished.
Quakers were prominent in campaigning against and publicizing the dire state of the prisons at the time. Elizabeth Fry documented the conditions that prevailed at Newgate prison, where the ladies' section was overcrowded with women and children, some of whom had not even received a trial. The inmates did their own cooking and washing in the small cells in which they slept on straw. In 1816, Fry founded a prison school for the children who were imprisoned with their parents. She also began a system of supervision and required the women to sew and to read the Bible. In 1817, she helped to found the Association for the Reformation of the Female Prisoners in Newgate.
Development of the modern prison
The theory of the modern prison system was born in London, influenced by the utilitarianism of Jeremy Bentham. Bentham's panopticon introduced the principle of observation and control that underpins the design of the modern prison. The notion of prisoners being incarcerated as part of their punishment and not simply as a holding state until trial or hanging, was at the time revolutionary. His views influenced the establishment of the first prisons used as criminal rehabilitation centers. At a time when the implementation of capital punishment for a variety of relatively trivial offenses was on the decline, the notion of incarceration as a form of punishment and correction held great appeal to reform-minded thinkers and politicians.
In the first half of the 19th century, capital punishment came to be regarded as inappropriate for many crimes that it had previously been carried out for, and by the mid-19th century, imprisonment had replaced the death penalty for the most serious offenses except for murder.
The first state prison in England was the Millbank Prison, established in 1816 with a capacity for just under 1,000 inmates. By 1824, 54 prisons had adopted the disciplinary system advocated by the SIPD. By the 1840s, penal transportation to Australia and the use of hulks was on the decline, and the Surveyor-General of convict prisons, Joshua Jebb, set an ambitious program of prison building in the country, with one large prison opening per year. Pentonville prison opened in 1842, beginning a trend of ever increasing incarceration rates and the use of prison as the primary form of crime punishment. Robert Peel's Gaols Act 1823 introduced regular visits to prisoners by chaplains, provided for the payment of jailers and prohibited the use of irons and manacles.
In 1786, the state of Pennsylvania passed a law that mandated that all convicts who had not been sentenced to death would be placed in penal servitude to do public works projects such as building roads, forts, and mines. Besides the economic benefits of providing a free source of hard labor, the proponents of the new penal code also thought that this would deter criminal activity by making a conspicuous public example of consequences of breaking the law. However, what actually ended up happening was frequent spectacles of disorderly conduct by the convict work crews, and the generation of sympathetic feelings from the citizens who witnessed the mistreatment of the convicts. The laws quickly drew criticism from a humanitarian perspective (as cruel, exploitative and degrading) and from a utilitarian perspective (as failing to deter crime and delegitimizing the state in the eyes of the public). Reformers such as Benjamin Rush came up with a solution that would enable the continued use of forced labor while keeping disorderly conduct and abuse out of the eyes of the public. They suggested that prisoners be sent to secluded "houses of repentance" where they would be subjected (out of the view of the public) to "bodily pain, labor, watchfulness, solitude, and silence ... joined with cleanliness and a simple diet".
Pennsylvania soon put this theory into practice, and turned its old jail at Walnut Street in Philadelphia into a state prison, in 1790. This prison was modeled on what became known as the "Pennsylvania system" (or "separate system"), and placed all prisoners into solitary cells with nothing other than religious literature, made them wear prison uniforms, and forced them to be completely silent to reflect on their wrongs. New York soon built the Newgate state prison in Greenwich Village, which was modeled on the Pennsylvania system, and other states followed.
But, by 1820, faith in the efficacy of legal reform had declined, as statutory changes had no discernible effect on the level of crime, and the prisons, where prisoners shared large rooms and booty including alcohol, had become riotous and prone to escapes. In response, New York developed the Auburn system in which prisoners were confined in separate cells and prohibited from talking when eating and working together, implementing it at Auburn State Prison and Sing Sing at Ossining. The aim of this was rehabilitative: the reformers talked about the penitentiary serving as a model for the family and the school and almost all the states adopted the plan (though Pennsylvania went even further in separating prisoners). The system's fame spread and visitors to the U.S. to see the prisons included de Tocqueville who wrote Democracy in America as a result of his visit.
The use of prisons in Continental Europe was never as popular as it became in the English-speaking world, although state prison systems were largely in place by the end of the 19th century in most European countries. After the unification of Italy in 1861, the government reformed the repressive and arbitrary prison system they inherited, and modernized and secularized criminal punishment by emphasizing discipline and deterrence. Italy developed an advanced penology under the leadership of Cesare Lombroso (1835–1909).
Another prominent prison reformer who made important contributions was Alexander Paterson who advocated for the necessity of humanizing and socializing methods within the prison system in Great Britain and America.
Staff
Prisons employ people to run and maintain the prison while keeping control of the inmates. Oftentimes, the number of people employed within a prison depends upon factors such as the size of the prison, how many inmates the prison has, and how much funding the prison gets. Staff may include:
The Warden, also known as a Governor is the official who is in charge of the prison and heads all the staff.
Security staff, also known as prison guards, are enforcement officials who are in charge of enforcing prison rules among the inmates. Thus they are responsible for the care, custody and control of the prison.
Teachers are employed to provide education for inmates to use after their release, in order to reduce the likelihood of the inmates reoffending.
Case managers are people who perform correctional casework in an institutional setting; develop, evaluate, and analyze program needs and other data about inmates; evaluate progress of individual offenders in the institution; coordinate and integrate inmate training programs; develop social histories; evaluate positive and negative aspects in each case situation, and develop release plans.
Prison counselors are people who are employed to intervene therapeutically with various clients, the majority of whom happen to be offenders. These interventions include prison adjustment, prerelease and postrelease vocational and marital/family readjustment, and work with adolescent adjustment problems.
Medical workers are doctors and nurses who are tasked with providing the inmates with healthcare.
A work release supervisor is someone who is tasked with monitoring inmates outside of the prison during a work release program.
In private prisons, contractors are people who pay the prison for the use of prison labor and supplied the prisoners with work.
Prisons may also provide religious workers to meet the religious need for inmates. Religious workers are also in charge of the weddings when inmates marry someone outside the prison.
In addition to the prison staff, inmate labor may be utilized for tasks within the prison, such as cooking food for the other inmates or providing cleaning services.
Design
Security
Prisons are normally surrounded by fencing, walls, earthworks, geographical features, or other barriers to prevent escape. Multiple barriers, concertina wire, electrified fencing, secured and defensible main gates, armed guard towers, security lighting, motion sensors, dogs and roving patrols may all also be present depending on the level of security.
Remotely controlled doors, CCTV monitoring, alarms, cages, restraints, nonlethal and lethal weapons, riot-control gear and physical segregation of units and prisoners may all also be present within a prison to monitor and control the movement and activity of prisoners within the facility.
Modern prison designs have increasingly sought to restrict and control the movement of prisoners throughout the facility and also to allow a smaller prison staff to monitor prisoners directly, often using a decentralized "podular" layout. (In comparison, 19th-century prisons had large landings and cell blocks which permitted only intermittent observation of prisoners.) Smaller, separate and self-contained housing units known as "pods" or "modules" are designed to hold 16 to 50 prisoners and are arranged around exercise yards or support facilities in a decentralized "campus" pattern. A small number of prison officers, sometimes a single officer, supervise each pod. The pods contain tiers of cells arranged around a central control station or desk from which a single officer can monitor all the cells and the entire pod, control cell doors and communicate with the rest of the prison.
Pods may be designed for high-security "indirect supervision", in which officers in segregated and sealed control booths monitor smaller numbers of prisoners confined to their cells. An alternative is "direct supervision", in which officers work within the pod and directly interact with and supervise prisoners, who may spend the day outside their cells in a central "dayroom" on the floor of the pod. Movement in or out of the pod to and from exercise yards, work assignments or medical appointments can be restricted to individual pods at designated times and is generally centrally controlled. Goods and services, such as meals, laundry, commissary, educational materials, religious services and medical care can increasingly be brought to individual pods or cells as well. Some modern prisons may exclude certain inmates from the general population, usually for safety reasons, such as those within solitary confinement, celebrities, political figures and former law enforcement officers, those convicted of sexual crimes and/or crimes against children, or those on the medical wing or protective custody.
Inmate security classifications
Generally, when an inmate arrives at a prison, they go through a security classification screening and risk assessment that determines where they will be placed within the prison system. Classifications are assigned by assessing the prisoner's personal history and criminal record, and through subjective determinations made by intake personnel (which include mental health workers, counselors, clerical staff, sheriff deputies, prison unit managers, and others). This process will have a major impact on the prisoner's experience, determining their security level, educational and work programs, mental health status (e.g. the determination of whether they will be placed in a mental health unit), and many other factors. This sorting of prisoners is one of the fundamental techniques through which the prison administration maintains control over the inmate population and attempts to reduce risks and liabilities in an attempt to create an orderly and secure prison environment. In some countries, prisoners are made to wear a prison uniform and are stripped of nearly all personal possessions [[with the exception of approved medical devices like glasses.
The levels of security within a prison system are categorized differently around the world, but tend to follow a distinct pattern. At one end of the spectrum are the most secure facilities ("maximum security"), which typically hold prisoners that are considered dangerous, disruptive or likely to try to escape. Furthermore, in recent times, supermax prisons have been created where the custody level goes beyond maximum security for people such as terrorists or political prisoners deemed a threat to national security, and inmates from other prisons who have a history of violent or other disruptive behavior in prison or are suspected of gang affiliation. These inmates have individual cells and are kept in lockdown, often for more than 23 hours per day. Meals are served through "chuck-holes" in the cell door, and each inmate is allowed one hour of outdoor exercise per day, alone. They are normally permitted no contact with other inmates and are under constant surveillance via closed-circuit television cameras.
On the other end are "minimum security" prisons which are most often used to house those for whom more stringent security is deemed unnecessary. For example, prisoners convicted of white-collar crime (which rarely results in incarceration) are almost always sent to minimum-security prisons due to them having committed nonviolent crimes. Lower-security prisons are often designed with less restrictive features, confining prisoners at night in smaller locked dormitories or even cottage or cabin-like housing while permitting them free movement around the grounds to work or partake in activities during the day. Some countries (such as Great Britain) also have "open" prisons where prisoners are allowed home-leave or part-time employment outside of the prison. Suomenlinna Island facility in Finland is an example of one such "open" correctional facility. The prison has been open since 1971 and, as of September 2013, the facility's 95 male prisoners leave the prison grounds on a daily basis to work in the corresponding township or commute to the mainland for either work or study. Prisoners can rent flat-screen televisions, sound systems, and mini-refrigerators with the prison-labor wages that they can earn—wages range between 4.10 and €7.30 per hour. With electronic monitoring, prisoners are also allowed to visit their families in Helsinki and eat together with the prison staff. Prisoners in Scandinavian facilities are permitted to wear their own clothes.
There are fundamental differences between the security level of men's prisons and that of women's prisons. Male prisons tend to have higher, or more severe, security levels/classifications than female prisons. This is even noticeable when comparing the construction and design of male prisons which tend to have very tall walls and towers, barbed wire and other serious security measures whereas these types of high level security measures are absent at many female prisons. This is due to multiple factors including females being convicted of less severe offences, and being less likely to be convicted of violent offences, in comparison to males, and due to female prisoners being less likely to be violent than male prisoners.
Common facilities
Modern prisons often hold hundreds or thousands of inmates, and must have facilities onsite to meet most of their needs, including dietary, health, fitness, education, religious practices, entertainment, and many others. Conditions in prisons vary widely around the world, and the types of facilities within prisons depend on many intersecting factors including funding, legal requirements, and cultural beliefs/practices. Nevertheless, in addition to the cell blocks that contain the prisoners, there are also certain auxiliary facilities that are common in prisons throughout the world.
Kitchen and dining
Prisons generally have to provide food for a large number of individuals, and thus are generally equipped with a large institutional kitchen. There are many security considerations, however, that are unique to the prison dining environment. For instance, cutlery equipment must be very carefully monitored and accounted for at all times, and the layout of prison kitchens must be designed in a way that allows staff to observe activity of the kitchen staff (who are usually prisoners). The quality of kitchen equipment varies from prison to prison, depending on when the prison was constructed, and the level of funding available to procure new equipment. Prisoners are often served food in a large cafeteria with rows of tables and benches that are securely attached to the floor. However, inmates that are locked in control units, or prisons that are on "lockdown" (where prisoners are made to remain in their cells all day) have trays of food brought to their cells and served through "chuck-holes" in the cell door. Prison food in many developed countries is nutritionally adequate for most inmates.
Healthcare
Prisons in wealthy, industrialized nations provide medical care for most of their inmates. Additionally, prison medical staff play a major role in monitoring, organizing, and controlling the prison population through the use of psychiatric evaluations and interventions (psychiatric drugs, isolation in mental health units, etc.). Prison populations are largely from poor minority communities that experience greater rates of chronic illness, substance abuse, and mental illness than the general population. This leads to a high demand for medical services, and in countries such as the US that do not provide tax-payer funded healthcare, prison is often the first place that people are able to receive medical treatment (which they could not afford outside).
Some prison medical facilities include primary care, mental health services, dental care, substance abuse treatment, and other forms of specialized care, depending on the needs of the inmate population and the willingness of the prison to provide for these needs. Health care services in many prisons have long been criticized as inadequate, underfunded, and understaffed, and many prisoners have experienced abuse and mistreatment at the hands of prison medical staff who are entrusted with their care.
In the United States, a million incarcerated people suffer from mental illness without any assistance or treatment for their condition. The tendency of a convicted criminal to reoffend, known as the rate of recidivism, is unusually high for those with the most serious disorders. Analysis of data in 2000 from several forensic hospitals in California, New York and Oregon found that with treatment the rate of recidivism was "much lower" than for untreated mentally ill offenders.
Library and educational facilities
Some prisons provide educational programs for inmates that can include basic literacy, secondary education, or even college education. Prisoners seek education for a variety of reasons, including the development of skills for after release, personal enrichment and curiosity, finding something to fill their time, or trying to please prison staff (which can often secure early release for good behavior). However, the educational needs of prisoners often come into conflict with the security concerns of prison staff and with a public that wants to be "tough on crime" (and thus supports denying prisoners access to education). Whatever their reasons for participating in educational programs, prison populations tend to have very low literacy rates and lack of basic mathematical skills, and many have not completed secondary education. This lack of basic education severely limits their employment opportunities outside of prison, leading to high rates of recidivism, and research has shown that prison education can play a significant role in helping prisoners reorient their lives and become successful after reentry.
Many prisons also provide a library where prisoners can check out books, or do legal research for their cases. Often these libraries are very small, consisting of a few shelves of books. In some countries, such as the United States, drastic budget cuts have resulted in many prison libraries being shut down. Meanwhile, many nations that have historically lacked prison libraries are starting to develop them. Prison libraries can dramatically improve the quality of life for prisoners, who have large amounts of empty time on their hands that can be occupied with reading. This time spent reading has a variety of benefits including improved literacy, ability to understand rules and regulations (leading to improved behavior), ability to read books that encourage self-reflection and analysis of one's emotional state, consciousness of important real-world events, and education that can lead to successful re-entry into society after release.
In 2024, the American Library Association published Standards for Library Services for the Incarcerated or Detained.
Literacy programs
Under the Federal Bureau of Prisons in the United States, all prison institutions offer literacy programs to expand inmates' educational opportunities. Some scholars in the field see prison literacy programs as organic, tactical spaces that resist institutionalization. They warn against the dehumanizing nature of rehabilitative practices and encourage the maintenance of agency and control in these programs to prevent them from becoming self-serving entities that cause further exploitation. Others argue that certain education systems are falsely advertised as a perfect solution when in reality there are much larger systemic issues at hand. Rather than trying to shape inmates into helpful workforce members upon release, scholars like Michael Sutcliffe argue that there needs to be a focus on re-enfranchising members and helping them share their voices. Still others advocate for styles of collective life-writing to capture the experience of incarcerated individuals and fight against exclusionary institutions. Taking an alternative approach, queer literacy frameworks have also been supported by scholars like Alexandra Cavallaro who see the incorporation of LGBTQ individuals' stories as key to promoting lifelong learning. Keeping forward solutions in mind, rhetorical listening is a final approach that is spread by leaders like Wendy Hinshaw.
Recreation and fitness
Many prisons provide limited recreational and fitness facilities for prisoners. The provision of these services is controversial, with certain elements of society claiming that prisons are being "soft" on inmates, and others claiming that it is cruel and dehumanizing to confine people for years without any recreational opportunities. The tension between these two opinions, coupled with lack of funding, leads to a large variety of different recreational procedures at different prisons. Prison administrators, however, generally find the provision of recreational opportunities to be useful at maintaining order in the prisons, because it keeps prisoners occupied and provides leverage to gain compliance (by depriving prisoners of recreation as punishment). Examples of common facilities/programs that are available in some prisons are: gyms and weightlifting rooms, arts and crafts, games (such as cards, chess, or bingo), television sets, and sports teams. Additionally, many prisons have an outdoor recreation area, commonly referred to as an "exercise yard".
Control units
Most prisoners are part of the "general population" of the prison, members of which are generally able to socialize with each other in common areas of the prison. A or (also called a "block" or "isolation cell") is a highly secure area of the prison, where inmates are placed in solitary confinement to isolate them from the general population. Other prisoners that are often segregated from the general population include those who are in protective custody, or who are on suicide watch, and those whose behavior presents a threat to other prisoners.
Other facilities
In addition to the above facilities, others that are common include prison factories and workshops, visiting areas, mail rooms, telephone and computer rooms, a prison store (often called a "canteen") where prisoners can purchase goods with prison commissary. Some prisons have a death row where prisoners who have been sentenced to death await execution and an execution room, where the death sentence is carried out. In places like Singapore and Malaysia, there is place for corporal punishment (carried out by caning).
Special types
Youth detention facilities
Prisons for juveniles are known by a variety of names, including "youth detention facilities", "juvenile detention centers", and "reformatories". The purpose of youth detention facilities is to keep young offenders away from the public, while working towards rehabilitation. The idea of separately treating youthful and adult offenders is a relatively modern idea. The earliest known use of the term "juvenile delinquency" was in London in 1816, from where it quickly spread to the United States. The first juvenile correctional institution in the United States opened in 1825 in New York City. By 1917, juvenile courts had been established in all but 3 states. It was estimated that in 2011 more than 95,000 juveniles were locked up in prisons and jails in the United States (the largest youth prisoner population in the world). Besides prisons, many other types of residential placement exist within juvenile justice systems, including youth homes, community-based programs, training schools and boot camps.
Like adult facilities, youth detention centers in some countries are experiencing overcrowding due to large increases in incarceration rates of young offenders. Crowding can create extremely dangerous environments in juvenile detention centers and juvenile correctional facilities. Overcrowding may also lead to the decrease in availability to provide the youth with much needed and promised programs and services while they are in the facility. Many times the administration is not prepared to handle the large number of residents and therefore the facilities can become unstable and create instability in simple logistics.
In addition to overcrowding, juvenile prisons are questioned for their overall effectiveness in rehabilitating youth. Many critics note high juvenile recidivism rates, and the fact that most of the youths that are incarcerated are those from lower socio-economic classes (who often suffer from broken families, lack of educational/job opportunities, and violence in their communities).
Women's prisons
In the 19th century, a growing awareness that female prisoners had different needs to male prisoners led to the establishment of dedicated prisons for women. In modern times, it is the norm for female inmates to be housed in either a separate prison or a separate wing of a unisex prison. The aim is to protect them from physical and sexual abuse that would otherwise occur.
In the Western world, the guards of women's prisons are usually female, though not always. For example, in federal women's correction facilities of the United States, 70% of guards are male. Rape and sexual offenses remain commonplace in many women's prisons, and are usually underreported. Two studies in the late 2000s noted that because a high proportion of female inmates have experienced sexual abuse in the past, they are particularly vulnerable to further abuse.
The needs of mothers during pregnancy and childbirth often conflict with the demands of the prison system. The Rebecca Project, a non-profit organization that campaigns for women's rights issues, reports that "In 2007, the Bureau of Justice Statistics stated that, on average, 5% of women who enter into state prisons are pregnant and in jails [local prisons] 6% of women are pregnant". The standard of care that female prisoners receive before and after giving birth is often far worse than the standard expected by the general population, and sometimes almost none is given. In some countries, female prisoners may be restrained while giving birth. In many countries including the United States, mothers will frequently be separated from their baby after giving birth.
Research has shown a significant link between females in prison and brain injury which supports research that shows incarcerated females are overwhelmingly victims of domestic violence (mainly male violence against women).
Military prisons and prisoner-of-war camps
Prisons have formed parts of military systems since the French Revolution. France set up its system in 1796. They were modernized in 1852 and since their existence, are used variously to house prisoners of war, unlawful combatants, those whose freedom is deemed a national security risk by military or civilian authorities, and members of the military found guilty of a serious crime. Military prisons in the United States have also been converted to civilian prisons, to include Alcatraz Island. Alcatraz was formerly a military prison for soldiers during the American Civil War.
In the American Revolution, British prisoners held by the U.S. were assigned to local farmers as laborers. The British kept American sailors in broken down ship hulls with high death rates.
In the Napoleonic wars, the broken down hulks were still in use for naval prisoners. One French surgeon recalled his captivity in Spain, where scurvy, diarrhea, dysentery, and typhus abounded, and prisoners died by the thousands:
"These great trunks of ships were immense coffins, in which living men were consigned to a slow death.... [In the hot weather we had] black army bread full of gritty particles, biscuit full of maggots, salt meat that was already decomposing, rancid lard, spoiled cod, [and] stale rice, peas, and beans."
In the American Civil War, at first prisoners of war were released, after they promised not to fight again unless formally exchanged. When the Confederacy refused to exchange black prisoners the system broke down, and each side built large-scale POW camps. Conditions in terms of housing, food, and medical care were bad in the Confederacy, and the Union retaliated by imposing harsh conditions.
By 1900, the legal framework of the Geneva and Hague Convention provided considerable protection. In the First World War, millions of prisoners were held on both sides, with no major atrocities. Officers received privileged treatment. There was an increase in the use of forced labor throughout Europe. Food and medical treatment were generally comparable to what active duty soldiers received, and housing was much better than front-line conditions.
Political prisons and administrative detention
Political prisoners are people who have been imprisoned because of their political beliefs, activities and affiliations. There is much debate about who qualifies as a "political prisoner". The category of "political prisoner" is often contested, and many regimes that incarcerate political prisoners often claim that they are merely "criminals". Others who are sometimes classified as "political prisoners" include prisoners who were politicized in prison, and are subsequently punished for their involvement with political causes.
Many countries maintain or have in the past had a system of prisons specifically intended for political prisoners. In some countries, dissidents can be detained, tortured, executed, and/or "disappeared" without trial. This can happen either legally, or extralegally (sometimes by falsely accusing people and fabricating evidence against them).
Administrative detention is a classification of prisons or detention centers where people are held without trial.
Psychiatric facilities
Some psychiatric facilities have characteristics of prisons, particularly when confining patients who have committed a crime and are considered dangerous. In addition, many prisons have psychiatric units dedicated to housing offenders diagnosed with a wide variety of mental disorders. The United States government refers to psychiatric prisons housing federal inmates as "Federal Medical Centers (FMC)".
Prison population
Some jurisdictions refer to the prison population (total or per-prison) as the prison muster.
In 2021, the World Prison Brief reported that at least 11.5 million people were imprisoned worldwide.
In 2021, the United States of America had the world's largest prison population, with over 2 million people in American prisons or jails—up from 744,000 in 1985—making 1 in every 200 American adults a prisoner. In 2017, the nonprofit organization Prison Policy Initiative estimated that the United States government spent an estimated US$80.7 billion to maintain prisons. CNBC estimated that the cost of maintaining the US prison system was US$74 billion per year. This increases government spending on prisons. , the US no longer has the highest incarceration rate in the world, with El Salvador now having the highest.
Not all countries have experienced a rise in prison population: Sweden closed four prisons in 2013 due to a significant drop in the number of inmates. The head of Sweden's prison and probation services characterized the decrease in the number of Swedish prisoners as "out-of-the-ordinary", with prison numbers in Sweden falling by around 1% a year since 2004.
The United Nations Office on Drugs and Crime website hosts data regarding prison populations around the world, including "Persons held – by sex, by age group," "Persons held – by status and sex" and "Prison capacity and overcrowding – totals".
Economics of the prison industry
In the United States alone, more than $74 billion per year is spent on prisons, with over 800,000 people employed in the prison industry. As the prison population grows, revenues increase for a variety of small and large businesses that construct facilities, and provide equipment (security systems, furniture, clothing), and services (transportation, communications, healthcare, food) for prisons. These parties have a strong interest in the expansion of the prison system since their development and prosperity directly depends on the number of inmates.
The prison industry also includes private businesses that benefit from the exploitation of the prison labor. Some scholars, using the term prison-industrial complex, have argued that the trend of "hiring out prisoners" is a continuation of the slavery tradition, pointing out that the Thirteenth Amendment to the United States Constitution freed slaves but allowed forced labor for people convicted of crimes. Prisons are very attractive to employers, because prisoners can be made to perform a great array of jobs, under conditions that most free laborers would not accept (and would be illegal outside of prisons): sub-minimum wage payments, no insurance, no collective bargaining, lack of alternative options, etc. Prison labor can soon deprive the free labor of jobs in a number of sectors, since the organized labor turns out to be uncompetitive compared to the prison counterpart.
Social effects
Internal
Prisons can be difficult places to live and work in, even in developed countries in the present day. By their very definition, prisons house individuals who may be prone to violence and rule-breaking. It is also typical that a high proportion of inmates have mental health concerns. A 2014 US report found that this included 64% of local jail inmates, 54% of state prisoners and 45% of federal prisoners. The environment may be worsened by overcrowding, poor sanitation and maintenance, violence by prisoners against other prisoners or staff, staff misconduct, prison gangs, self-harm, and the widespread smuggling of illegal drugs and other contraband. The social system within the prison commonly develops an "inmate code", an informal set of internal values and rules that govern prison life and relationships, but that may be at odds with the interests of prison management or external society, compromising future rehabilitation and increasing recidivism rates. In some cases, disorder can escalate into a full-scale prison riot, which could lead to serious injury or death en masse. Academic research has found that poor conditions tend to increase the likelihood of violence within prisons.
External
Prisoners can face difficulty re-integrating back into society upon their release. They often have difficulty finding work, earn less money when they do find work, and experience a wide range of medical and psychological issues. Many countries have a high recidivism rate. According to the Bureau of Justice Statistics, 67.8% of released prisoners in the United States are rearrested within three years and 76.6% are rearrested within five years. If the prisoner has a family, they are likely to suffer socially and economically from the prisoner's absence.
If a society has a very high imprisonment rate, these effects become noticeable not just on family units, but also on entire poor communities or communities of color. The expensive cost of maintaining a high imprisonment rate also costs money that must come at the expense of either the taxpayer or other government agencies.
Theories of punishment and criminality
A variety of justifications and explanations are put forth for why people are imprisoned by the state. The most common of these are:
Rehabilitation: Theories of rehabilitation argue that the purpose of imprisonment is to change prisoners' lives in a way that will make them productive and law-abiding members of society once they are released. The idea was promoted by 19th century reformers, who promoted prisons as a humane alternative to harsh punishments of the past. Many governments and prison systems have adopted rehabilitation as an official aim. In the United States and Canada, prison agencies are often referred to as "Corrections" services for this reason.
Deterrence: Theories of deterrence argue that by sentencing criminals to extremely harsh penalties, other people who might be considering criminal activities will be so terrified of the consequences that they will choose not to commit crimes out of fear.
Incapacitation: Theories of argue that while prisoners are incarcerated, they will be unable to commit crimes, thus keeping communities safer.
Retribution: Theories of argue that the purpose of imprisonment is to cause a sufficient level of misery to the prisoner, in proportion to the perceived seriousness of their crime. These theories do not necessarily focus on whether or not a particular punishment benefits the community, but instead are based upon a belief that some kind of moral balance will be achieved by "paying back" the prisoner for the wrongs they have committed.
Evaluation
Academic studies have been inconclusive as to whether high imprisonment rates reduce crime rates in comparison to low imprisonment rates; only a minority suggest it creates a significant reduction, and others suggest it increases crime.
Prisoners are at risk of being drawn further into crime, as they may become acquainted with other criminals, trained in further criminal activity, exposed to further abuse (both from staff and other prisoners) and left with criminal records that make it difficult to find legal employment after release. All of these things can result in a higher likelihood of reoffending upon release.
This has resulted in a series of studies that are skeptical towards the idea that prison can rehabilitate offenders. As Morris and Rothman (1995) point out, "It's hard to train for freedom in a cage." A few countries have been able to operate prison systems with a low recidivism rate, including Norway and Sweden. On the other hand, in many countries including the United States, the vast majority of prisoners are rearrested within 3 years of their release. Prison reform organizations such as the Howard League for Penal Reform are not entirely opposed to attempting to rehabilitate offenders, but instead argue that most prisoners would be more likely to be rehabilitated if they received a punishment other than prison.
The National Institute of Justice argues that offenders can be deterred by the fear of being caught but are unlikely to be deterred by the fear or experience of the punishment. Like Lawrence W. Sherman, they argue that better policing is a more effective way to reduce crime rates.
The argument that prisons can reduce crime through incapacitation is more widely accepted, even among academics who doubt that prisons can rehabilitate or deter offenders. A dissenting argument from Arrigo and Milovanovic, who argue that prisoners will simply continue to victimize people inside of the prison and that this harm has impacts on the society outside.
Alternatives
Modern prison reform movements generally seek to reduce prison populations. A key goal is to improve conditions by reducing overcrowding. Prison reformers also argue that alternative methods are often better at rehabilitating offenders and preventing crime in the long term. Among the countries that have sought to actively reduce prison populations include Sweden, Germany and the Netherlands.
Alternatives to prison sentences include:
Fines
Community service
Execution
Suspended sentence: The offender performs of a period of probation, and only serves a prison sentence if the terms of probation are broken. This is similar to the Canadian concept of a conditional sentence.
House arrest/curfews: Sometimes a condition of a strict suspended/conditional sentence.
Mandatory treatment for drug offenders.
Rehabilitation programs, such as anger management classes.
Mental health treatment for offenders with mental illness.
Conditional discharge: The offender is not punished for the crime if they abide by certain conditions; typically they must not commit any further crimes within a designated period.
Other court orders that take away privileges from the offender, such as banning motoring offenders from driving.
Restorative justice programs, which overlap with the above methods. Restorative justice is based around arranging a mediation between the offender and victim, so that the offenders can take responsibility for their actions, "to repair the harm they've done—by apologizing, returning stolen money, or community service".
These alternatives do not eliminate the need for imprisonment altogether. Suspended sentences entail the threat of time in prison, while for others, actual imprisonment may be used as a punishment for noncompliance.
The prison abolition movement seeks to eliminate prisons altogether. It is distinct from prison reform, although abolitionists often support reform campaigns, regarding them as incremental steps towards abolishing prisons. The abolition movement is motivated by a belief that prisons are inherently ineffective and discriminatory. The movement is associated with libertarian socialism, anarchism and anti-authoritarianism, with some prison abolitionists arguing that imprisoning people for actions the state designates as crimes is not only inexpedient but also immoral.
See also
Notes
References
Sources
Further reading
Bernstein, Robin. Freeman's Challenge: The Murder that Shook America's Original Prison for Profit. Chicago: University of Chicago Press, 2024. .
Diiulio, John J., Governing Prisons: A Comparative Study of Correctional Management, Simon & Schuster, 1990. .
Fisher, George. "The birth of the prison retold." Yale Law Journal 104.6 (1995): 1235–1324. online free
Moran, Dominique (2015) Carceral Geography: Spaces and Practices of Incarceration Routledge ISBN 9781138308466
Skarbek, David. 2020. The Puzzle of Prison Order: Why Life Behind Bars Varies Around the World. Oxford University Press.
Slade, Gavin; Trochev, Alexei (2024). Our zona: the impact of decarceration and prison closure on local communities in Kazakhstan, Post-Soviet Affairs, 40:2, 71–87, DOI: 10.1080/1060586X.2024.2312081
External links
Federal Bureau of Prisons
Priston Radio Official website
Penology
Total institutions | Prison | Biology | 10,715 |
23,521,131 | https://en.wikipedia.org/wiki/C-41%20%28rocket%29 | C-41 was a two-stage Italian-built rocket, 75 kg (165 lb) in weight, part of a program to develop probe carrying rockets to study outer atmosphere. It was first launched on July 9, 1960, from the Salto di Quirra range. The project was managed by Lt.Col. Metallo (DGAM—Direzione Generali Armi e Munizioni) and Engineer Angeloni (SISPRE—Societa Italiana Sviluppo Propulsione a Reazione (Italian Society of Studies on Jet Propulsion)). To cut costs the C-41 recycled parts of existing weaponry. The first stage was powered by a cluster of four jets featuring interconnected combustion chambers. The payload carrying second stage was powered by a single engine of the same type. On the whole six C-41 were launched successfully. Successive development of probe carrying rockets was the task of the newly formed Space Research Committee within the CNR (Italian National Research Institution). The committee's president was the founder of Italian astronautics, Luigi Broglio.
See also
Italian Space Agency
References
Bibliography
L’Aeronautica Militare e lo spazio dagli albori agli albori agli anni ’70, Rivista Aeronautica 6/2003
AA.VV:, Le attività spaziali italiane dal dopoguerra all’istituzione dell’Agenzia Spaziale Italiana, Agenzia Spaziale Europea
Sounding rockets of Italy | C-41 (rocket) | Astronomy | 312 |
12,767,916 | https://en.wikipedia.org/wiki/Propiverine | Propiverine is an anticholinergic drug used for the treatment of urinary urgency, frequency and urge incontinence, all symptoms of overactive bladder syndrome. It is a muscarinic antagonist.
References
Carboxylate esters
Ethers
M1 receptor antagonists
M2 receptor antagonists
M3 receptor antagonists
M4 receptor antagonists
M5 receptor antagonists
Piperidines | Propiverine | Chemistry | 81 |
2,633,686 | https://en.wikipedia.org/wiki/Index%20of%20aerospace%20engineering%20articles | This is an alphabetical list of articles pertaining specifically to aerospace engineering. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.
A
Ablative laser propulsion —
Absolute value —
Acceleration —
Action —
Advanced Space Vision System —
Aeroacoustics —
Aerobrake —
Aerobraking —
Aerocapture —
Aerodynamics —
Aeroelasticity —
Aeronautical abbreviations —
Aeronautics —
Aerospace engineering —
Aerospike engine —
Aerostat —
Aft-crossing trajectory —
Aileron —
Air-augmented rocket —
Aircraft —
Aircraft flight control systems —
Aircraft flight mechanics —
Airfoil —
Airlock —
Airship —
Alcubierre drive —
Angle of attack —
Angular momentum —
Angular velocity —
Antimatter rocket —
Apsis —
Arcjet rocket —
Areal velocity —
ARP4761 —
Aspect ratio (wing) —
Astrodynamics —
Atmospheric reentry —
Attitude control —
Avionics —
B
Balloon —
Ballute —
Beam-powered propulsion —
Bernoulli's equation —
Bi-elliptic transfer —
Big dumb booster —
Bipropellant rocket —
Bleed air —
Booster rocket —
Breakthrough Propulsion Physics Program —
Buoyancy —
Bussard ramjet —
C
Canard —
Centennial challenges —
Center of gravity —
Center of mass —
Center of pressure —
Chord —
Collimated light —
Compressibility —
Computational fluid dynamics —
Computing —
Control engineering —
Conservation of momentum —
Crew Exploration Vehicle —
Critical mach —
Centrifugal compressor —
Chevron nozzle —
D
De Laval nozzle —
Deflection —
Delta-v —
Delta-v budget —
Density —
Derivative —
Digital Datcom —
Displacement (vector) —
DO-178B —
DO-254 —
Drag (physics) —
Drag coefficient —
Drag equation —
Dual mode propulsion rocket —
Delta wing —
E
Earth's atmosphere —
Electrostatic ion thruster —
Elliptic partial differential equation —
Energy —
Engineering —
Engineering economics —
Enstrophy —
Equation of motion —
Euler angles —
European Space Agency —
Expander cycle (rocket) —
F
Field Emission Electric Propulsion —
Fixed-wing aircraft —
Flight control surfaces —
Flight control system (aircraft) —
Flight control system (helicopter) —
Flight dynamics —
Floatstick —
Fluid —
Fluid dynamics —
Fluid mechanics —
Fluid statics —
Force —
Freefall —
Fuselage —
Future Air Navigation System —
Flying wing —
G
Gas-generator cycle (rocket) —
Geostationary orbit —
Geosynchronous orbit —
Glide ratio —
GPS —
Gravitational constant —
Gravitational slingshot —
Gravity —
Gravity turn —
Guidance, navigation and control —
Guidance system —
H
Hall-effect thruster —
Heat shield —
Helicopter —
Hohmann transfer orbit —
Hybrid rocket —
Hydrodynamics —
Hydrostatics —
Hyperbolic partial differential equation —
Hypersonic —
HyShot —
I
Impulse —
Inertial navigation system —
Instrument landing system —
Integral —
Internal combustion —
Interplanetary Transport Network —
Interplanetary travel —
Interstellar travel —
Ion thruster —
ISRO
J
Jet engine —
K
Kepler's laws of planetary motion —
Kessler syndrome —
Kestrel rocket engine —
Kinetic energy —
Kite —
Kutta condition —
Kutta–Joukowski theorem —
L
Landing —
Landing gear —
Lagrangian —
Lagrangian point —
Laser broom —
Laser Camera System —
Latus rectum —
Launch window —
Law of universal gravitation —
Leading edge —
Lift —
Lift coefficient —
Lightcraft —
Lighter than air —
Liquid air cycle engine —
Liquid fuels —
Liquid rocket propellants —
Lithobraking —
Loiter —
Low Earth orbit —
Lunar space elevator —
M
Mach number —
Magnetic sail —
Magnetoplasmadynamic thruster —
Mass —
Mass driver —
Mechanics of fluids —
Membrane mirror —
Metre per second —
Microwave landing system —
Mini-magnetospheric plasma propulsion —
Missile guidance —
Moment of inertia —
Momentum —
Momentum wheel —
Monopropellant rocket —
Motion —
Multistage rocket —
N
Nanotechnology —
NASA —
Navier–Stokes equations —
Newton (unit) —
Newton's laws of motion —
Nose cone design —
Nozzle —
O
Orbit —
Orbit phasing —
Orbiter Boom Sensor System —
Orbital elements —
Orbital inclination change —
Orbital maneuver —
Orbital node —
Orbital period —
Orbital stationkeeping —
Osculating orbit —
P
Parallel axes rule —
Parasitic drag —
Parawing —
Perpendicular axes rule —
Physics —
Planetary orbit —
Plasma (physics) —
Plug nozzle —
Pogo oscillation —
Prandtl-Glauert singularity —
Precession —
Pressure —
Pressure altitude —
Pressure-fed engine —
Propeller —
Proper orbital elements —
Pulsed inductive thruster —
Pulsed plasma thruster —
Propulsion —
Philippine Space Agency —
Q
R
Radar —
Railgun —
Ram accelerator —
Ramjet —
Reaction control system —
Reentry —
Reflection —
Relativistic rocket —
Remote Manipulator System —
Resistojet rocket —
Reusable launch system —
Reynolds number —
RL-10 (rocket engine) —
Rocket —
Rocket engine nozzle —
Rocket fuel —
Rocket launch —
Rudder —
S
SABRE —
Satellite —
Saturn (rocket family) —
Scalar (physics) —
Schlieren —
Schlieren photography —
Scramjet —
Second moment of area —
Shock wave —
SI —
Single-stage to orbit —
Skyhook (structure) —
Stream function —
Streamline —
Solar panel —
Solar sail —
Solar thermal rocket —
Solid of revolution —
Solid rocket —
Sound barrier —
Space activity suit —
Space elevator —
Space fountain —
Space plane —
Space Shuttle —
Space Shuttle external tank —
Space Shuttle Main Engine —
Space station —
Space suit —
Space technology —
Space transport —
Spacecraft —
Spacecraft design —
Spacecraft propulsion —
Special relativity —
Specific impulse —
Speed of sound —
Staged combustion cycle (rocket) —
Subsonic —
Supersonic —
Surface of revolution —
Sweep theory —
T
Tait–Bryan rotations —
Temperature —
Terminal velocity —
Test target —
Tether propulsion —
Thermal protection system —
Thermodynamics —
Thrust —
Thrust vector control —
Thruster —
Torricelli's equation —
Trajectory —
Trailing edge —
Trans Lunar Injection —
Transonic —
Transverse wave —
Tripropellant rocket —
Tsiolkovsky rocket equation —
Turbomachinery —
Two-stage-to-orbit —
U
UFO
UAV
V
V-2 rocket —
Variable specific impulse magnetoplasma rocket —
Velocity —
Viscometer —
Viscosity —
Vortex generator —
W
Wave drag —
Weight —
Weight function —
Wind tunnel —
Wing —
Wright Flyer —
Wright Glider of 1902 —
X
Y
Z
Aerospace engineering topics | Index of aerospace engineering articles | Engineering | 1,333 |
11,097,538 | https://en.wikipedia.org/wiki/Saturn%20V-3 | The Saturn V-3, also known as the Saturn MLV 5-3, was a conceptual heavy-lift launch vehicle that would have utilized new engines and new stages that were never used on the original Saturn V. The Saturn V-3 was studied by the NASA Marshall Space Flight Center in 1965.
The first stage, called MS-IC-1, was to have used new F-1 engines designated F-1A which utilized a pump-fed design, an anticipated 20% additional thrust, and a six-second improvement in specific impulse on an F-1, with the first stage stretched 20 feet.
The second and third stages, MS-II-2 and MS-IVB-2, were proposed to use new HG-3 engines in place of the J-2 engines, but were never used, although the HG-3 led to the development of the Space Shuttle Main Engine.
The V-3 booster was one of six Saturn MLV designs that never flew, but if these vehicles had been manufactured, they could possibly have been used for the Apollo Applications Program, Manned Orbiting Research Laboratory, Mars fly-by and Mars landing missions in the 1970s and 1980s.
References
Lowther, Scott, Saturn: Development, Details, Derivatives and Descendants
Saturn V Improvement Study, Final report, NASA Contract NAS8-11359.
Saturn V | Saturn V-3 | Astronomy | 274 |
23,581,112 | https://en.wikipedia.org/wiki/Selective%20receptor%20modulator | In the field of pharmacology, a selective receptor modulator or SRM is a type of drug that has different effects in different tissues. A SRM may behave as an agonist in some tissues while as an antagonist in others. Hence selective receptor modulators are sometimes referred to as tissue selective drugs or mixed agonists / antagonists. This tissue selective behavior is in contrast to many other drugs that behave either as agonists or antagonists regardless of the tissue in question.
Classes
Classes of selective receptor modulators include:
Selective androgen receptor modulator (SARM)
Selective estrogen receptor modulator (SERM)
Selective glucocorticoid receptor modulator (SEGRM)
Selective progesterone receptor modulator (SPRM)
Selective PPAR modulator (SPPARM) including SPPARMγ (affecting the PPARγ) and SPPARMα (PPARα)
See also
Agonist–antagonist
Selective glucocorticoid receptor agonist (SEGRA)
References
Pharmacodynamics | Selective receptor modulator | Chemistry | 215 |
23,986,665 | https://en.wikipedia.org/wiki/Bandstacked | The term bandstacked applies to an antenna or satellite feedhorn (LNBF) that is designed to operate on two or more bands of frequencies. Usually, a portion of the radio frequency spectrum that has been divided into a low band and a high band.
This example is for a C Band LNBF that operates with two different local oscillator frequencies.
Model Number B1SAT STACK
I/P Frequency 3.7-4.2 GHz
O/P Frequency 950-2050 MHz
LO Frequency Lower Band 5.15 GHz, Upper Band 5.75 GHz
One application is to send both H and V signals to the receiver on one cable at the same time.
Other LNBF are voltage switched by the receiver for V or H signal.
· Extended Frequency 3.7 GHz ~ 4.2 GHz
· Bandstacked LNBF
This also can be applied to the design and construction of VHF antennas, typically base station antennas that can cover the VHF low band and high band.
This should not be confused with stacked antenna array configurations.
Radio technology | Bandstacked | Technology,Engineering | 216 |
75,186,104 | https://en.wikipedia.org/wiki/Cavorite | Cavorite is a fictional material first depicted by H. G. Wells in The First Men in the Moon, a 1901 scientific romance. Developed by Cavor, a reclusive physicist, it has the ability to negate the force of gravity, enabling him and a businessman named Bedford to travel to the Moon using a spherical spacecraft propelled by Cavorite blinds. The material was later referenced in numerous works of science fiction media, and its theoretical implications have been discussed by critics.
Creation
Into Other Worlds posits that Cavorite was based on a combination of lunarium, a fictional metal from A Voyage to the Moon (1827) by George Tucker, and apergy, from Across the Zodiac (1880) by Percy Greg, and that since Wells was unconcerned about the process of traveling to the Moon, he "borrowed freely from his predecessors".
Critical analysis
Beyond Reason states that a material such as Cavorite is impossible in the real world, as it contradicts the laws of conservation of energy. It would allow for the instant invention of a perpetual motion machine, such as a bicycle whose wheel, partly shielded from gravity, would spin at a faster and faster pace until it reached its mechanical limits.
Natural Space in Literature calls Cavorite a "rather fantastic" invention, saying that it was only slightly more scientific than the cannon shot in Jules Verne's From the Earth to the Moon (1865), but noting that the story itself focused more on realism than Verne's did. The book describes Cavorite as a convenient plot device that turned the reader's attention to "human questions" as soon as possible, comparing it to the shield of Achilles. It notes that while critics demanded realism in science fiction, Wells created a self-consistent story within the reality he created. In contrast, Sense of Wonder: A Century of Science Fiction called Cavorite "much more fanciful" than Verne's Columbiad cannon.
The Intellectuals and the Masses hypothesizes that the disaster almost caused by Cavorite destroying the atmosphere was representative of Wells' anxiety due to overpopulation and the ecological damage it caused, due to his childhood experiences.
References
Fictional materials
H. G. Wells | Cavorite | Physics | 454 |
56,288,945 | https://en.wikipedia.org/wiki/Ilijas%20Farah | Ilijas Farah (born 18 February 1966) is a Canadian-Serbian mathematician and a professor of mathematics at York University in Toronto and at the Mathematical Institute of Serbian Academy of Sciences and Arts, Belgrade, Serbia. His research focuses on applications of logic to operator algebras.
Career
Farah was born in Sremska Mitrovica, Serbia. He received his BSc and MSc in 1988 and 1992 respectively from Belgrade University and his PhD in 1997 from the University of Toronto.
He is a Research Chair in Logic and Operator Algebras at York University, Toronto. Before moving to York University he was an NSERC Postdoctoral Fellow, York University (1997–99), a Hill Assistant Professor at Rutgers University (1999–2000), and a professor at CUNY–Graduate center and College of Staten Island (2000–02).
Farah was an invited speaker at the International Congress of Mathematicians, Seoul 2014, section on Logic and Foundations, where he presented his work on applications of logic to operator algebras.
Awards, distinctions, and recognitions
Sacks prize for the best doctorate in Mathematical Logic, 1997
Governor General's gold medal for one of the two best doctorates at the University of Toronto, 1998
The Canadian Association for Graduate Studies/University Microfilms International Distinguished Dissertation Award, for the best dissertation in engineering, medicine and the natural sciences in Canada, 1998.
Dean's award for outstanding research, York University, 2006.
Faculty Excellence in Research Award (Established Research Award), Faculty of Science, York University, 2017
Sources
External links
Ilijas Farah: Krajnja proširenja modela, MSc thesis, Belgrade university 1992.
Living people
Canadian mathematicians
Mathematical logicians
Set theorists
1966 births
Yugoslav emigrants to Canada
Canadian people of Serbian descent | Ilijas Farah | Mathematics | 358 |
500,338 | https://en.wikipedia.org/wiki/Outrigger | An outrigger is a projecting structure on a boat, with specific meaning depending on types of vessel. Outriggers may also refer to legs on a wheeled vehicle that are folded out when it needs stabilization, for example on a crane that lifts heavy loads.
Powered vessels and sailboats
An outrigger describes any contraposing float rigging beyond the side (gunwale) of a boat to improve the vessel's stability. If a single outrigger is used it is usually but not always windward. The technology was originally developed by the Austronesian people. There are two main types of boats with outriggers: double outriggers (prevalent in maritime Southeast Asia) and single outriggers (prevalent in Madagascar, Melanesia, Micronesia and Polynesia). Multihull ships are also derived from outrigger boats.
In an outrigger canoe and in sailboats such as the proa, an outrigger is a thin, long, solid, hull used to stabilise an inherently unstable main hull. The outrigger is positioned rigidly and parallel to the main hull so that the main hull is less likely to capsize. If only one outrigger is used on a vessel, its weight reduces the tendency to capsize in one direction and its buoyancy reduces the tendency in the other direction.
On a keelboat, "outrigger" refers to a variety of structures by which the running rigging (such as a sheet) may be attached outboard (outside the lateral limits) of the boat's hull. The Racing Rules of Sailing generally prohibit such outriggers, though they are explicitly permitted on specific classes, such as the IMOCA Open 60 used in several major offshore races.
Fishing
In fishing from vessels, an outrigger is a pole or series of poles that allow boats to trawl more lines in the water without tangling and simulates a school of fish.
Rowing
In a rowing boat or galley, an outrigger (or rigger) is a triangular frame that holds the rowlock (into which the oar is slotted) away from the saxboard (or gunwale in gig rowing) to optimize leverage. Wooden outriggers appear on the new trireme around the 7th or 6th centuries BC and later on Italian galleys around AD 1300, while Harry Clasper (1812–1870), a British professional rower, popularised the use of the modern tubular-metal version and the top rowing events accepted the physiological and ergonomic advantages so acceded to its use in competitions. In recent decades, some manufacturers of racing shells have developed wing-riggers which are reinforced arcs or flattened tubular projections akin to aircraft wings, instead of conventional triangular structures.
See also
Outrigger canoe
Outrigger canoe racing
Racing shell
Sailing canoe
Training wheels
References
Watercraft components
Canoeing and kayaking equipment
Rowing equipment
Structural system | Outrigger | Technology,Engineering | 601 |
1,559,901 | https://en.wikipedia.org/wiki/Mean%20motion | In orbital mechanics, mean motion (represented by n) is the angular speed required for a body to complete one orbit, assuming constant speed in a circular orbit which completes in the same time as the variable speed, elliptical orbit of the actual body. The concept applies equally well to a small body revolving about a large, massive primary body or to two relatively same-sized bodies revolving about a common center of mass. While nominally a mean, and theoretically so in the case of two-body motion, in practice the mean motion is not typically an average over time for the orbits of real bodies, which only approximate the two-body assumption. It is rather the instantaneous value which satisfies the above conditions as calculated from the current gravitational and geometric circumstances of the body's constantly-changing, perturbed orbit.
Mean motion is used as an approximation of the actual orbital speed in making an initial calculation of the body's position in its orbit, for instance, from a set of orbital elements. This mean position is refined by Kepler's equation to produce the true position.
Definition
Define the orbital period (the time period for the body to complete one orbit) as P, with dimension of time. The mean motion is simply one revolution divided by this time, or,
with dimensions of radians per unit time, degrees per unit time or revolutions per unit time.
The value of mean motion depends on the circumstances of the particular gravitating system. In systems with more mass, bodies will orbit faster, in accordance with Newton's law of universal gravitation. Likewise, bodies closer together will also orbit faster.
Mean motion and Kepler's laws
Kepler's 3rd law of planetary motion states, the square of the periodic time is proportional to the cube of the mean distance, or
where a is the semi-major axis or mean distance, and P is the orbital period as above. The constant of proportionality is given by
where μ is the standard gravitational parameter, a constant for any particular gravitational system.
If the mean motion is given in units of radians per unit of time, we can combine it into the above definition of the Kepler's 3rd law,
and reducing,
which is another definition of Kepler's 3rd law. μ, the constant of proportionality, is a gravitational parameter defined by the masses of the bodies in question and by the Newtonian constant of gravitation, G (see below). Therefore, n is also defined
Expanding mean motion by expanding μ,
where M is typically the mass of the primary body of the system and m is the mass of a smaller body.
This is the complete gravitational definition of mean motion in a two-body system. Often in celestial mechanics, the primary body is much larger than any of the secondary bodies of the system, that is, . It is under these circumstances that m becomes unimportant and Kepler's 3rd law is approximately constant for all of the smaller bodies.
Kepler's 2nd law of planetary motion states, a line joining a planet and the Sun sweeps out equal areas in equal times, or
for a two-body orbit, where is the time rate of change of the area swept.
Letting t = P, the orbital period, the area swept is the entire area of the ellipse, dA = ab, where a is the semi-major axis and b is the semi-minor axis of the ellipse. Hence,
Multiplying this equation by 2,
From the above definition, mean motion n = . Substituting,
and mean motion is also
which is itself constant as a, b, and are all constant in two-body motion.
Mean motion and the constants of the motion
Because of the nature of two-body motion in a conservative gravitational field, two aspects of the motion do not change: the angular momentum and the mechanical energy.
The first constant, called specific angular momentum, can be defined as
and substituting in the above equation, mean motion is also
The second constant, called specific mechanical energy, can be defined,
Rearranging and multiplying by ,
From above, the square of mean motion n2 = . Substituting and rearranging, mean motion can also be expressed,
where the −2 shows that ξ must be defined as a negative number, as is customary in celestial mechanics and astrodynamics.
Mean motion and the gravitational constants
Two gravitational constants are commonly used in Solar System celestial mechanics: G, the Newtonian constant of gravitation and k, the Gaussian gravitational constant. From the above definitions, mean motion is
By normalizing parts of this equation and making some assumptions, it can be simplified, revealing the relation between the mean motion and the constants.
Setting the mass of the Sun to unity, M = 1. The masses of the planets are all much smaller, . Therefore, for any particular planet,
and also taking the semi-major axis as one astronomical unit,
The Gaussian gravitational constant k = , therefore, under the same conditions as above, for any particular planet
and again taking the semi-major axis as one astronomical unit,
Mean motion and mean anomaly
Mean motion also represents the rate of change of mean anomaly, and hence can also be calculated,
where M1 and M0 are the mean anomalies at particular points in time, and Δt (≡ t1-t0) is the time elapsed between the two. M0 is referred to as the mean anomaly at epoch t0, and Δt is the time since epoch.
Formulae
For Earth satellite orbital parameters, the mean motion is typically measured in revolutions per day. In that case,
where
d is the quantity of time in a day,
G is the gravitational constant,
M and m are the masses of the orbiting bodies,
a is the length of the semi-major axis.
To convert from radians per unit time to revolutions per day, consider the following:
From above, mean motion in radians per unit time is:
therefore the mean motion in revolutions per day is
where P is the orbital period, as above.
See also
Gaussian gravitational constant
Kepler orbit
Mean anomaly
Mean longitude
Mean motion resonance
Orbital elements
Notes
References
External links
Glossary entry mean motion at the US Naval Observatory's Astronomical Almanac Online
Orbits
Equations of astronomy | Mean motion | Physics,Astronomy | 1,277 |
33,698,097 | https://en.wikipedia.org/wiki/CPS%20operon | The capsule biosynthesis, or CPS operon, is a section of the genome present in some Escherichia coli, of which regulates the production of polysaccharides making up the bacterial capsule. These polysaccharides help protect the bacteria from harsh environments, toxic chemicals, and bacteriophages.
The CPS operon contains genes which code for the following proteins:
Wza - a lipoprotein which may form a channel in the bacterial outer membrane.
Wzb - a cytoplasmic regulatory phosphatase which dephosphorylates Wzc.
Wzc - a tyrosine kinase found in the bacterial inner membrane. Participates in polymerization of capsule polysaccharides.
Wzx - Transfers new polysaccharide units across the inner membrane.
Wzy - Assembles longer polysaccharide chains using units introduced by Wzx.
The CPS operon is likely transcriptionally regulated by the Rcs (regulation of capsule synthesis) proteins. Reduced levels of membrane-derived oligosaccharides result in autophosphorylation of RcsC. This results in a phosphate group being transferred from RcsC to RcsB. RcsB then binds to RcsA, forming a complex which acts on the CPS promoter and activates transcription of the CPS genes.
The same operon is present in Klebsiella species, possibly as a result of horizontal gene transfer.
References
Escherichia coli genes
Operons | CPS operon | Chemistry | 316 |
11,930,474 | https://en.wikipedia.org/wiki/French%20Gothic%20architecture | French Gothic architecture is an architectural style which emerged in France in 1140, and was dominant until the mid-16th century. The most notable examples are the great Gothic cathedrals of France, including Notre-Dame Cathedral, Reims Cathedral, Chartres Cathedral, and Amiens Cathedral. Its main characteristics are verticality, or height, and the use of the rib vault and flying buttresses and other architectural innovations to distribute the weight of the stone structures to supports on the outside, allowing unprecedented height and volume. The new techniques also permitted the addition of larger windows, including enormous stained glass windows, which fill the cathedrals with light.
French scholars divide the Gothic of their country into four phases: British and American historians use similar periods.
(Primary Gothic) or (First Gothic), from short before 1140 until shortly after 1180, marked by tribunes above the aisles of basilicas. The British and American term for the period is Early Gothic.
Gothique Classique or (Classic Gothic), from the 1180s to the first third of 13th century, marked by basilicas without lateral tribunes and with triforia without windows. The British and American term is for the period is High Gothic. and Some buildings of this phase, like Chartres Cathedral, are included in Early Gothic; others, like the Reims Cathedral and the western parts of Amiens Cathedral, are included in High Gothic.
(Shining Gothic), from the second third of 13th century to the first half of 14th century, marked by triforia with windows and a general preference for stained glass instead of stone walls. It forms the greater portion of High Gothic. American and British historians also use the term Rayonnant.
(Flaming Gothic), since mid 14th century, marked by swinging and flaming (that makes the term) forms of tracery. British and American historians use the same term.
French scholars divide the Gothic of their country into four phases: British and American historians use similar periods.
The French style was widely copied in other parts of northern Europe, particularly Germany and England. It was gradually supplanted as the dominant French style in the mid-16th century by French Renaissance architecture.
Origins
French Gothic architecture was the result of the emergence in the 12th century of a powerful French state centered in the Île-de-France. During the reign of Louis VI of France (1081–1137), Paris was the principal residence of the Kings of France, Reims the place of coronation, and the Abbey of Saint-Denis became their ceremonial burial place. The Abbot of Saint-Denis, Suger, was a counselor of Louis VI and Louis VII, as well as a historian. He oversaw the reconstruction of the ambulatory of Saint-Denis, making it the first and most influential example of Gothic architecture in France. The first complete Gothic cathedral, Sens Cathedral, was finished shortly afterwards.
Over the later course of the Capetian dynasty (1180 to 1328), three Kings: Philip Augustus (1180–1223), Louis IX of France (1226–1270), and Philip le Bel (1285–1314), established France as the major economic and political power on the Continent. The period also saw the founding of the University of Paris or Sorbonne. It produced the High Gothic and the Flamboyant Gothic styles, and the construction of some of the most famous cathedrals, including Chartres Cathedral, Reims Cathedral, and Amiens Cathedral.
Primary or Early Gothic Style - Saint-Denis, Sens, Senlis, and Notre Dame
The birthplace of the new style was the Basilica of Saint-Denis in the Île-de-France, not far north of Paris where, in 1137, the Abbé Suger began the reconstruction of the Carolingian-era abbey church. Just to the west of the original church, he began building a new structure with two towers, and then, from 1140 to 1144, he began to reconstruct the old church. Most of his modifications were traditional, but he made one remarkable innovation; he decided to create a new choir at the east end of the building, using the pointed arch and the rib vault in the construction of the choir and the ambulatory with radiating chapels. The use of rib vaults, and buttresses outside supporting the walls, allowed the elimination of the traditional walls between the chapels, and the installation of large stained glass windows. This gave the ambulatory a striking openness, light, and greater height.
The builders then constructed the nave of the church, also using rib vaults. It was constructed in four levels; the arcades on the ground floor whose two rows of columns received the ribs of the ceiling vaults; the tribune above it, a gallery which concealed the massive contreforts or buttresses which pressed against the walls; the triforium, another, narrower gallery; and, just below the ceiling, the or clerestorey, where the windows were located. The resulting greater height and light differed dramatically from the heaviness of Romanesque architecture. On the facade of the church, Suger introduced another innovation; he used columns in the form of statues of saints to decorate the portal of the church, adding a new element of verticality to the facade. This idea too was soon copied in new cathedrals. Ninety years later, the upper parts of the choir and the whole nave had to be renewed because of signs of decay; the new upper choir (on the arcades of the Primary Gothic) was built with a triforium with windows. This was the onset of Rayonnant style (see below).
The first cathedral constructed in the new style was Sens Cathedral, begun between 1135 and 1140 and consecrated in 1160. It featured a Gothic choir, and six-part rib vaults over the nave and collateral aisles, alternating pillars and doubled columns to support the vaults, and flying buttresses. But note, much of the ambulatory is still Romanesque, and all adjacent chapels are younger. One of the builders believed to have worked on that Cathedral, William of Sens, later traveled to England and became the architect who reconstructed the choir of Canterbury Cathedral in the Gothic style. Sens Cathedral was soon followed by Senlis Cathedral (begun 1160), and the most prominent of all, Notre-Dame Cathedral in Paris (begun 1160). Their builders abandoned the traditional plans and introduced the new Gothic elements. The builders of Notre Dame went further by introducing the flying buttress, heavy columns of support outside the walls connected by arches to the walls, which received and counterbalanced the thrust from the rib vaults of the roof. This allowed the builders to construct higher walls and larger windows.
Classic Gothic or High Gothic Cathedrals – Chartres, Bourges, Reims, western parts of Amiens
The second phase of Gothic in France is called Gothique Classique or Classic Gothic. The similar phase in English is called High Gothic. From the end of the 12th century until the middle of the 13th century, the Gothic style spread from the cathedrals in Île-de-France to appear in other cities of northern France, notably Chartres Cathedral (begun 1200); Bourges Cathedral (1195 to 1230), Reims Cathedral (1211–1275), and Amiens Cathedral (begun 1250); The characteristic Gothic elements were refined to make the new cathedrals taller, wider, and more full of light. At Chartres, the use of the flying buttresses allowed the elimination of the tribune level, which allowed much higher arcades and nave, and larger windows. The pillars were made of a central column surrounded by four more slender columns, which reached up to support the arches of the vaulted ceiling. The rib vault changed from six to four ribs, simpler and stronger. The flying buttresses at Amiens and Chartes were strengthened by an additional arch and with a supporting arcade, allowing even higher walls and more windows. At Reims, the buttresses were given greater weight and strength by the addition of heavy stone pinnacles on top. These were often decorated with statues of angels, and became an important decorative element of the High Gothic style. Another practical and decorative element, the gargoyle, appeared; it was an ornamental rain spout that channeled the water from the roof away from the building. At Amiens, the windows of the nave were made larger, and an additional row of clear glass windows (the ) flooded the interior with light. The new structural technologies allowed the enlargement of the transepts and the choirs at the east end of the cathedrals, creating the space for a ring of well-lit chapels.
Rayonnant Gothic – Sainte-Chapelle and the rose windows of Notre-Dame
The third period of French Gothic architecture, from the second half of the 13th century until the 1370s, is termed Rayonnant ("Radiant") in both French and English, describing the radiating pattern of the tracery in the stained glass windows, and also describing the tendency toward the use of more and more stained glass and less masonry in the design of the structure, until the walls seemed entirely made of glass. The most celebrated example was the chapel of Sainte-Chapelle, attached to the royal residence on the Palais de la Cité. An elaborate system of exterior columns and arches reduced the walls of the upper chapel to a thin framework for the enormous windows. The weight of each of the masonry gables above the archivolt of the windows also helped the walls to resist the thrust and to distribute the weight.
Other landmarks of the Rayonnant Gothic are the two rose windows on the north and south of the transept of Notre-Dame Cathedral, whereas earlier rose windows, like those of Amiens Cathedral, were framed by stone and occupied only a portion of the wall, these two windows, with a delicate lacelike framework, occupied the entire space between the pillars.
Flamboyant Gothic - Rouen Cathedral, Sainte-Chapelle de Vincennes
The Flamboyant Gothic style appeared beginning about 1350 and lasted until about 1500. Its characteristic features were more exuberant decoration, as the nobles and wealthy citizens of mostly northern French cities competed to build more and more elaborate churches and cathedrals. It took its name from the sinuous, flame-like designs which ornamented windows. Other new features included the arc en accolade, a window decorated with an arch, stone pinnacles and floral sculpture. It also featured an increase in the number of nervures, or ribs, that supported and decorated each vault of the ceiling, both for greater support and decorative effect. Notable examples of Flamboyant Gothic include the western facade of Rouen Cathedral and Sainte-Chapelle de Vincennes in Paris, both built in the 1370s; and the Choir of Mont Saint Michel Abbey (about 1448).
Gothic architecture in the French regions
The most famous examples of Gothic architecture are found in the Île-de-France and Champagne, but other French regions created their own original versions of the style.
Norman Gothic
Normandy at the end of the 12th century saw the construction of several notable Gothic cathedrals and churches. The characteristic features of Norman Gothic were sharply pointed arches, lavish use of decorative molding, and walls pierced with numerous passages. Norman architects and builders were active not only in Normandy, but also across the Channel in England. The high-quality Norman stone was cut and transported to England for use in English cathedrals.
Notable examples of Norman Gothic include Lisieux Cathedral, Fécamp Abbey, the chevet of Abbey of Saint-Étienne, Caen; Rouen Cathedral; Coutances Cathedral, the chevet of Le Mans Cathedral; Bayeux Cathedral; and the celebrated monastery at Mont-Saint-Michel.
Angevin Gothic
The Angevin Gothic style or Plantagenet style in the province of Anjou features vaults with elegant decorative ribs, as well as ornate columns. The style is found in the interior of Angers Cathedral (1032–1523), though many of the Gothic elements of the facade were replaced with Renaissance elements and towers. A fine example of Angevin Gothic is found in the medieval Saint Jean Hospital in Angers, which now contains the Musée Jean-Lurçat, a museum of contemporary tapestries.
Maine Gothic
Poitiers Cathedral in the historic province of Maine also features a distinctive regional Gothic style. It was begun in 1162 under King Henry II of England and Eleanor of Aquitaine. Its distinctive features, like those of Angevin Gothic, include convex vaults with ribs in decorative designs.
Burgundian Gothic
Burgundy also had its own version of Gothic, found in Nevers Cathedral (1211–1331), Dijon Cathedral (1280–1325), Chalon Cathedral (1220–1522), and Auxerre Cathedral (13th-16th century). The Burgundian Gothic tended to be more sober and monumental than the more ornate northern style, and often included elements of earlier Romanesque churches on the same site, such as the Romanesque crypt beneath the Gothic choir at Auxerre Cathedral. Other Burgundian features included colourful tile roofs in geometric patterns (Langres Cathedral).
Meridional Gothic
The south of France had its own distinct variation of the Gothic style: the Meriodonal or Southern French Gothic. A prominent example is Albi Cathedral in the Tarn Department, built between 1282 and 1480. It was originally constructed as a fortress, then transformed into a church. Due to a lack of suitable stone, it was constructed almost entirely of brick, and is one of the largest brick buildings in the world. In the Jacobins church of Toulouse, the grafting of a single apse of polygonal plan on a church with two vessels gave birth to a starry vault whose complex organization preceded by more than a century the Flamboyant Gothic. Tradition refers to this masterpiece as "palm tree" because the veins gush out of the smooth shaft of the column, like the fronds of palm trees.
Gothic civil architecture
The largest civic building built in the Gothic style in France was the Palais des Papes (Palace of the Popes) in Avignon, constructed between 1252 and 1364, when the Popes fled the political chaos and wars enveloping Rome. Given the complicated political situation, it combined the functions of a church, a seat of government and a fortress.
In the 15th century, following the Late Gothic or Flamboyant period, some elements of Gothic decoration borrowed from cathedrals began to appear in civil architecture, particularly in the region of Flanders in northern France, and in Paris. The Hôtel de Ville of Compiègne has an imposing Gothic bell tower, featuring a spire surrounded by smaller towers, and its windows are decorated with ornate accolades or ornamental arches. Similarly, flamboyant town halls were found in Arras, Douai, and Saint-Quentin, Aisne, and across the border in Belgium in Brussels and Bruges. Unfortunately, many of the finest buildings were destroyed during World War I, due to their proximity to the front lines.
Gothic features also appeared in the elaborate residences built by the nobility and wealthy bourgeoisie in Paris and other large cities. Examples include the Hôtel Cluny (now the Musée de Cluny – Musée national du Moyen Âge) in Paris, and particularly the palatial house built by merchant Jacques Cœur in Bourges (1440–1450). Another good example in Paris is the Tour Jean-sans-Peur, a nobleman's townhouse, which features a Gothic watch tower and a flamboyant gothic ceiling.
Transition between Gothic and Renaissance
During the Middle Ages Prosperous French cities competed to build the largest cathedral or the highest tower. One of the drawbacks of French Gothic architecture was its cost; it required many skilled craftsmen working for decades. Due to downturns in the economy, a number of French cathedrals were begun but never finished. They also sometimes suffered when the ambitions of the architects exceeded their technical skills. One example was Beauvais Cathedral. Its patrons and architects sought to build the tallest church in the world. with a vaulted choir 48 meters high, taller than its nearby competitor, Amiens Cathedral, at 42 meters. Work began in 1225 but the roof of the vault was too heavy for the walls, and partially collapsed in 1272. They thickened the walls and rebuilt the vault and in 1569 they completed a tower, 72 meters high, which from 1569 to 1573 made Beauvais Cathedral the tallest structure in the world. However, in 1573, the new tower collapsed, fortunately without any casualties. The church remains today as it was, with the choir, some of the ambulatory, apse, some chapels, but no nave or tower.
Beginning in the 1530s, the Flamboyant Gothic style of French religious and civil architecture also began to show the influence of the Italian Renaissance. Charles VIII of France and Louis XII of France had both participated in military campaigns in Italy, and had seen the new architecture there. Large numbers of Italian stonemasons had come to Paris to work on the new Pont Notre-Dame (1507–1512) and other construction sites. The Fontaine des Innocents, built by sculptor Jean Goujon to celebrate the entrance of Henry II into Paris in 1549, was the first Renaissance monument in the city. It was soon followed by the new facade of the Cour Carré of the Louvre, also decorated by Jean Goujon. The new Paris Hotel de Ville (1533–1568) was also constructed in an Italianate rather than Gothic style. Most important of all, the new Tuileries Palace by Philippe Delorme, built for Catherine de' Medici, begun in 1564, was inspired by Italian palaces.
Religious buildings were slower to change. The Church of the Carmes-Deschaussé (1613–1620) on rue Vaugirard in Paris, and especially the church of St-Gervais-et-St-Protais by Salomon de Brosse (1615–21) with a facade based on the superposition of the three orders of classical architecture, represented the new model. However, the Gothic style remained prominent in new churches. The Church of Saint Eustache in Paris (1532–1640), which rivaled Notre-Dame in size, combined a Gothic plan with Renaissance decoration.
In the course of the 17th century, the French classical style of François Mansart began to dominate; then, under Louis XIV, the grand French classical style, practiced by Jules Hardouin-Mansart, Louis Le Vau, and Claude Perrault, took center stage. Landmarks of the Gothic style, such as Notre-Dame, were modified with new interiors designed in the new style. Following the new fashion of his patron, Louis XIV, the poet Molière ridiculed the Gothic style in a 1669 poem: "...the insipid taste of Gothic ornamentation, these odious monstrosities of an ignorant age, produced by the torrents of barbarism...".
During the French Revolution, Gothic churches were symbols of the old regime and became targets for the Revolutionaries; the cathedrals were nationalized, and stripped of ornament and valuables. The statues of the Biblical figures on the facade of Notre-Dame were beheaded, under the false belief that they were statues of the French Kings. Under Napoleon Bonaparte, the cathedrals were returned to the church, but were left in a lamentable state of repair.
Military architecture
In the 13th century, the design of the chateau fort, or castle, was modified, based on the Byzantine and Moslem castles the French knights had seen during the Crusades. The new kind of fortification was called Phillipienne, after Philippe Auguste, who had taken part in the Crusades. The new fortifications were more geometric, usually square, with a high main donjon or tower, in the center, which could be defended even if the walls of the castle were captured. The donjon of the Château de Vincennes, begun by Philip VI of France, is a good example. It is 52 meters high, the tallest military tower in Europe.
In the Phillipienne castle, other towers, usually round, were placed at the corners and along the walls, close enough together to support each other. The walls had two levels of walkways on the inside, an upper parapet with openings () from which soldiers could watch or fire arrows on besiegers below; narrow openings () through which they could be sheltered as they fired arrows; and floor openings (), from which they could drop rocks, burning oil or other objects on the besiegers. The upper walls also had protected protruding balconies, and , from which soldiers could see what was happening at the corners or on the ground below. In addition, the towers and walls were pierced with narrow vertical slits, called , through which archers could fire arrows. In later castles, the slits took the form of crosses, so that archers could fire , or crossbows, in different directions.
Castles were surrounded by deep moats, spanned by a single drawbridge. The entrance was also protected by a portcullis, which could be opened and closed. The walls at the bottom were often sloping, and protected with earthen barriers. A surviving example is the Château de Dourdan in the Seine-et-Marne department, near Nemours.
After the end of the Hundred Years' War (1337–1453), with improvements in artillery, the castles lost most of their military importance. They remained as symbols of the rank of their noble occupants; the narrowing openings in the walls were often widened into the windows of bedchambers and ceremonial halls. The tower of the Chateau of Vincennes became a royal residence.
In the 19th century, portions of the Gothic walls and towers of the Cité de Carcassonne were restored, with some modification, by Eugène Viollet-le-Duc. He also rebuilt the Château de Pierrefonds (1393–1407), an unfinished medieval castle, making it into a neo-Gothic residence for Napoleon III. This project was incomplete when Napoleon III was overthrown in 1870, but can be visited today.
Restoration and Gothic Revival
A large part of the Gothic architectural heritage of France, particularly the churches and monasteries, had been damaged or destroyed during the Revolution. Of the 300 churches in Paris in the 16th century, only 97 still were standing in 1800. The Basilica of St Denis had been stripped of its stained glass and monumental tombs, while the statues on the façade of the cathedral of Notre-Dame de Paris had been beheaded and taken down. Throughout the country, churches and monasteries had been demolished or turned into barns, cafes, schools, or prisons. The first effort to catalogue the remaining monuments was made in 1816 by Alexandre de Laborde, who wrote the first list of "Monuments of France". In 1831, interest in Gothic architecture grew even greater following the popular success of the romantic novel Notre-Dame de Paris by Victor Hugo. In 1832, Hugo wrote an article for the Revue des deux Mondes, which declared war against the "massacre of ancient stones" and the "demolishers" of France's past. Louis Philippe declared that restoration of churches and other monuments would be a priority of his regime. In October 1830, the position of Inspector of Historical Monuments had been created by the Interior Minister, François Guizot, a professor of history at the Sorbonne. In 1833, Prosper Mérimée became its second Inspector, and by far the most energetic and long-lasting. He held the position for twenty-seven years.
Under Louis Philippe, French Gothic architecture was officially recognized as a treasure of French culture. Under Mérimée's direction, the first efforts to restore major Gothic monuments began. In 1835, the church of Saint Séverin in Paris was among the first to undergo restoration, followed in 1836 by Sainte-Chapelle, which had been turned into a storage house for government archives after the Revolution. The restoration of Saint-Chapelle as led by Félix Duban with Jean-Baptiste Antoine Lassus and a young Eugène Viollet-le-Duc. In 1843, Lassus and Viollet-le-Duc won the competition for the restoration of Notre-Dame de Paris. Over the rest of the 19th century, all of the major Gothic cathedrals of France underwent extensive restoration.
French Gothic architecture also experienced a modest revival, largely confined to new churches. Neo-Gothic churches built in Paris included Sainte-Clothilde by Theodore Ballu (1841–1857), and Saint-Laurent, Paris by Simon-Claude-Constant Dufeux (1862–1865). Jean-Baptiste Lassus became the most prolific neo-Gothic architect in France, constructing Saint-Nicolas de Nantes (1840), Sacré-Coeur de Moulins (1849), Saint-Pierre de Dijon (1850), Saint-Jean-Baptiste de Belleville (1853) and the Église de Cusset (1855). The Saint-Eugene-Sainte-Cécile in Paris by Louis-Auguste Boileau and Adrien-Louis Lasson (1854–1855) was the most innovative example of neo-Gothic; it combined a traditional Gothic design with a modern iron framework. Jules Verne was married in the church in 1857.
Characteristics
The rib vault
The Gothic style emerged from innovative use of existing technologies, particularly the pointed arch and the rib vault. The rib vault was known in the earlier Romanesque period, but it was not widely or effectively used until the Gothic period. The crossed ribs of the vault carried the weight outwards and downwards, to clusters of supporting pillars and columns. The earlier rib vaults, used at Sens Cathedral and Notre-Dame Cathedral, had six compartments bordered by ribs and the crossing arch, which transferred the weight to alternating columns and pillars. A new innovation appeared during the High Gothic: the four-part rib vault, which was used in Chartres Cathedral, Amiens Cathedral and Reims Cathedral. The ribs of this vault distributed the weight more equally to the four supporting pillars below and established a closer connection between the nave and the lower portions of the church walls, and between the arcades below and the windows above. This allowed for greater height and thinner walls and contributed to the strong impression of verticality given by the newer Cathedrals.
The flying buttress
The second major innovation of the Gothic style was the flying buttress, which was first used at Notre-Dame Cathedral. This transferred the thrust of the weight of the roof outside the walls, where it was countered by the weight of the buttress. Heavy stone pinnacles were added to the top of the buttresses, to precisely counterbalance the thrust from inside the walls. The buttress allowed a significant reduction in the thickness of the cathedral walls, and permitted the use of larger windows in the interior of the church. In churches such as Sainte Chapelle, due to buttresses, the walls were made almost entirely of stained glass.
The development of rib-vaults and buttresses brought gradual changes to the interior structure of cathedrals. Early Gothic cathedrals had the walls of the nave built in four levels: a gallery with columns on the ground level; then the tribune, a gallery with windows; then the triforium, a row of smaller windows; and finally the high windows, just below the vaults. During the High Gothic period, with the development of the four-part rib vault and the flying buttress, the tribune was eliminated at Chartres and other new cathedrals, allowing taller windows and arcades. By the 15th century, at Rouen Cathedral, the triforium also disappeared, and the walls between the traverses were filled with high windows.
The portal and tympanum
Another innovative feature of the French Gothic cathedral was the design of the portal or entry, which by long Christian tradition faced west. The Basilica of St Denis had a triple portal, decorated with columns in the form of statues of apostles and saints around the doorways, and biblical scenes crowded with statuary over the doorways. This triple portal was adopted by all the major cathedrals. A tympanum over the portal, crowded with sculptural figures illustrating a biblical story became a feature of Gothic cathedrals. Following the example of Amiens, the tympanum over the central portal traditionally depicted the Last Judgement, the right portal showed the coronation of the Virgin Mary, and the left portal showed the lives of saints who were important in the diocese.
Stained glass and the rose window
Large stained glass windows and rose windows were another defining feature of the Gothic style. Some Gothic windows, like those at Chartres, were cut into the stone walls. Other windows, such as those in the chapels of Notre-Dame and Reims, were in stone frames installed into the walls. The most common form was an oculus, a small round window with two lancets, or windows with pointed arches, just below it. The rose window was the most famous type of the Gothic style. They were placed in the transepts and the portals to provide light to the nave. The largest rose windows were ten meters in diameter. They had a framework of stone armatures often in an ornate floral pattern, to help them resist the wind. Gothic windows were in a stone frame separate from the wall, not cut into the wall.
The early windows were made of pieces of tinted glass, touched up with grisaille painting, and held in place by pieces of lead that outlined the figures. As the windows grew larger, more intense colors were used. After 1260, the colors became lighter, and the combination of grisaille and pale shades of yellow became more common. Chartres Cathedral and Le Mans Cathedral have some of the finest surviving original windows.
Sculpture and symbolism - the "Book for the Poor"
The Gothic cathedral was a , literally a "book for the poor", covered with sculpture illustrating biblical stories, for the vast majority of parishioners who were illiterate. These largely illustrated stories from the Bible, but also included stories and figures from mythology and more complicated symbols taken from medieval philosophical and scientific teachings such as alchemy.
The exteriors of cathedrals and other Gothic churches were decorated with sculptures of a variety of fabulous and frightening grotesques or monsters. These included the gargoyle, the chimera, the dragon, the tarasque, and others, taken largely from legend and mythology. They were part of the visual message for the illiterate worshippers, symbols of the evil and danger that threatened those who did not follow the teachings of the church.
The gargoyle also had a more practical purpose. They were the rain spouts of the Cathedral; rainwater ran from the roof into lead gutters, then down channels on the flying buttresses to the mouths of the gargoyles. The longer the gargoyle, the farther the water was projected from the walls, protecting the walls and windows from water damage. Multiple numbers were used to distribute the water as widely as possible.
Amid all the religious figures, some of the sculptural decoration was devoted to illustrating medieval science and philosophy. The porch of Notre-Dame Cathedral in Paris and of Amiens Cathedral are decorated with similar small carved figures holding circular plaques with symbols of transformation taken from alchemy. The central pillar of the central door of Notre-Dame features a statue of a woman on a throne holding a sceptre in her left hand, and in her right hand, two books, one open (symbol of public knowledge), and the other closed (esoteric knowledge), along with a ladder with seven steps, symbolizing the seven steps alchemists followed in their scientific quest of trying to transform ordinary metal into gold.
Another common feature of Gothic cathedrals was a design of a labyrinth, usually found in stone on the floor in a central part of the cathedral. Inspired by the labyrinth in Greek legend constructed by King Minos as the home of the Minotaur, in cathedrals they were known as the "Path of Jerusalem" and symbolized the difficult and often roundabout path that a Christian sometimes had to follow in life to reach the gates of Paradise and salvation. Large labyrinths were originally found in Auxerre Cathedral, Sens Cathedral, Reims Cathedral, and Arras Cathedral, but these removed during various renovations in the 18th century. The best surviving examples are in Chartres Cathedral, in its original form, and in Amiens Cathedral, which was reconstructed in 1894.
The portal sculpture of Burgundy integrates classical literary elements with its 13th-century Gothic style. In Auxerre, two such examples of sculptures are upon the cathedral of Saint-Étienne depicting Hercules, a satyr, and a sleeping faun; the Chartres–Reims cathedral's north transept illustrates the biblical tale of David and Bathsheba. The Sens Cathedral's "Coronation of the Virgin" reflects a similar relief cathedral on the Notre Dame in Paris, and was created in a workshop that made minor contributions to Spanish Gothic architecture.
Timeline of notable buildings
Because of the lengthy period of construction of Gothic cathedrals, few were built in a single style. Most, like Notre-Dame, have a combination of features constructed in several different periods, as well as features constructed after the Gothic age. Also, different sources give varying dates for time periods. This list primarily uses the time periods given in LaRousse encyclopedia on-line and the on-line Pedagogical Dossier of Gothic Architecture of the Cité de l'Architecture et du Patrimoine, Paris.
Early Gothic, Transition, or Primitive Gothic (1130–1180)
1130: Sens Cathedral, the first French Gothic cathedral, begun (consecrated 1171).
1135: Basilica of Saint-Denis reconstruction in new style begun by Abbot Suger, The Gothic ambulatory was finished in 1144.
1145: Rouen Cathedral begun. (consecrated 1237)
1150: Noyon Cathedral begun. (completed 1231)
1153: Senlis Cathedral begun. (consecrated 1191)
1155: Laon Cathedral begun. Reconstructed with three traverses and completed in 1220
1150 c. Angers Cathedral rebuilding from Romanesque to Angevin Gothic beginning mid-12th century, completed 1250
1162: Poitiers Cathedral begun. (consecrated 1379)
1163: Notre Dame de Paris begun. Choir completed in 1172, Cathedral consecrated in 1182.
1170: Lyon Cathedral begun. (completed 14th century)
1170: Lisieux Cathedral in Normandy reconstruction begins from Romanesque to Gothic style. Work continued until 13th century.
High Gothic or Classic Gothic (1180–1230)
1183: Bourges Cathedral begun, nave was finished by 1255; consecrated in 1324.
1194: Chartres Cathedral begun to replace earlier church destroyed by fire. Consecrated 1260. Flamboyant north spire added after earlier spire destroyed by lightning.
1210: Coutances Cathedral, Normandy, begun. (completed 1274)
1210: Toul Cathedral reconstruction from Romanesque began. Flamboyant facade was added in the 15th century.
1211: Reims Cathedral begun. (completed 1345)
1217: Le Mans Cathedral begun. (consecrated 1254)
1220: Amiens Cathedral begun. (completed 1288). Rose window was added 1366–1341
1220 to 1270: Notre-Dame de Paris; Addition of transepts and rose windows, modified buttresses
1225: Beauvais Cathedral begun, but after tower falls in 1272 it is left unfinished
Rayonnant (1230–1420)
1231: Basilica of Saint-Denis enlarged with new nave, transept, and rose windows (completed 1264)
1238: Sainte-Chapelle on the Ile de la Cité in Paris begun. (completed 1248).
1252: in Avignon begun. (major enlargement and modification between 1334 and 1364)
1284: Conciergerie and Palais de la Cité begun on the Ile de la Cité in Paris
1340–1410: Château de Vincennes keep and tower
Flamboyant Gothic (1400–1520)
1405–1527: Notre-Dame de l'Épine (begun 1405–1406, completed 1527)
1435–1521: Church of Saint-Maclou, Rouen.
The west facade and towers of Rouen Cathedral rebuilt after a fire in the (16th century)
1493–1510: The north façade, south façade, and south porch of the Church of Notre-Dame de Louviers
1500–1508: Beauvais Cathedral south transept constructed
1507–13: Chartres Cathedral north tower is destroyed by lightning, and rebuilt in the Flamboyant style
See also
Building a Gothic cathedral
Early Gothic architecture
Rayonnant
Flamboyant
French Gothic stained glass windows
High Gothic
Southern French Gothic
Gothic cathedrals and churches
Gothic architecture
Romanesque architecture
Architecture of cathedrals and great churches
References
Bibliography
Martindale, Andrew, Gothic Art, (1967), Thames and Hudson (in English and French);
Rivière, Rémi; Lavoye, Agnès (2007). La Tour Jean sans Peur, Association des Amis de la tour Jean sans Peur.
External links
Mapping Gothic France, a project by Columbia University and Vassar College with a database of images, 360° panoramas, texts, charts and historical maps
Architectural history
Architectural styles
European architecture
Catholic architecture
12th-century architecture
13th-century architecture
14th-century architecture
15th-century architecture
16th-century architecture
Gothic | French Gothic architecture | Engineering | 7,696 |
208,292 | https://en.wikipedia.org/wiki/19%20%28number%29 | 19 (nineteen) is the natural number following 18 and preceding 20. It is a prime number.
Mathematics
Nineteen is the eighth prime number.
Number theory
19 forms a twin prime with 17, a cousin prime with 23, and a sexy prime with 13. 19 is the fifth central trinomial coefficient, and the maximum number of fourth powers needed to sum up to any natural number (see, Waring's problem). It is the number of compositions of 8 into distinct parts.
19 is the eighth strictly non-palindromic number in any base, following 11 and preceding 47. 19 is also the second octahedral number, after 6, and the sixth Heegner number.
In the Engel expansion of pi, 19 is the seventh term following and preceding . The sum of the first terms preceding 17 is in equivalence with 19, where its prime index (8) are the two previous members in the sequence.
Prime properties
19 is the seventh Mersenne prime exponent. It is the second Keith number, and more specifically the first Keith prime. In decimal, 19 is the third full reptend prime, and the first prime number that is not a permutable prime, as its reverse (91) is composite (where 91 is also the fourth centered nonagonal number).
19 × 91 = 1729, the first Hardy-Ramanujan number or taxicab number, also a Harshad number in base-ten, as it's divisible by the sum of its digits, 19.
1729 is also the nineteenth dodecagonal number.
19, alongside 109, 1009, and 10009, are all prime (with 109 also full reptend), and form part of a sequence of numbers where inserting a digit inside the previous term produces the next smallest prime possible, up to scale, with the composite number 9 as root. 100019 is the next such smallest prime number, by the insertion of a 1.
Numbers of the form 10n9 equivalent to 10x + 9 with x = n + 1, where n is the number of zeros in the term, are prime for , and probably prime for .
Otherwise, is the second base-10 repunit prime, short for the number .
The sum of the squares of the first nineteen primes is divisible by 19.
Figurate numbers and magic figures
19 is the third centered triangular number as well as the third centered hexagonal number.
The 19th triangular number is 190, equivalently the sum of the first 19 non-zero integers, that is also the sixth centered nonagonal number.
19 is the first number in an infinite sequence of numbers in decimal whose digits start with 1 and have trailing 9's, that form triangular numbers containing trailing zeroes in proportion to 9s present in the original number; i.e. 19900 is the 199th triangular number, and 1999000 is the 1999th.
Like 19, 199 and 1999 are also both prime, as are 199999 and 19999999. In fact, a number of the form 19n, where n is the number of nines that terminate in the number, is prime for:
.
The number of nodes in regular hexagon with all diagonals drawn is nineteen.
Distinguishably, the only nontrivial normal magic hexagon is composed of nineteen cells, where every diagonal of consecutive hexagons has sums equal to 38, or twice 19.
A hexaflexagon is a strip of nineteen alternating triangular faces that can flex into a regular hexagon, such that any two of six colorings on triangles can be oriented to align on opposite sides of the folded figure.
Nineteen is also the number of one-sided hexiamonds, meaning there are nineteen ways of arranging six equiangular triangular polyforms edge-to-edge on the plane without turn-overs (and where holes are allowed).
can be used to generate the first full, non-normal prime reciprocal magic square in decimal whose rows, columns and diagonals — in a 18 x 18 array — all generate a magic constant of 81 = 92.
The next prime number to generate a like-magic square in base-ten is 383, the seventy-sixth prime number (where 19 × 4 = 76). A regular 19 x 19 magic square, on the other hand, has a magic constant of 3439 = 19 × 181.
Collatz problem
The Collatz sequence for nine requires nineteen steps to return to one, more than any other number below it. On the other hand, nineteen requires twenty steps, like eighteen. Less than ten thousand, only thirty-one other numbers require nineteen steps to return to one:
.
In abstract algebra
The projective special linear group represents the abstract structure of the 57-cell: a universal 4-polytope with a total of one hundred and seventy-one (171 = 9 × 19) edges and vertices, and fifty-seven (57 = 3 × 19) hemi-icosahedral cells that are self-dual.
In total, there are nineteen Coxeter groups of non-prismatic uniform honeycombs in the fourth dimension: five Coxeter honeycomb groups exist in Euclidean space, while the other fourteen Coxeter groups are compact and paracompact hyperbolic honeycomb groups.
There are also specifically nineteen uniform honeycombs inside the Euclidean tesseractic honeycomb group in 4-space. In 5-space, there are nineteen uniform polytopes with simplex symmetry.
There are infinitely many finite-volume Vinberg polytopes up through dimension nineteen, which generate hyperbolic tilings with degenerate simplex quadrilateral pyramidal domains, as well as prismatic domains and otherwise.
Vinberg polytopes of lowest rank mirrors exist up through the seventeenth dimension, where there exists a unique figure with nineteen facets. It is expressed with the simple Dynkin diagram, .
On the other hand, a cubic surface is the zero set in of a homogeneous cubic polynomial in four variables a polynomial with a total of twenty coefficients, which specifies a space for cubic surfaces that is 19-dimensional.
Finite simple groups
19 is the eighth consecutive supersingular prime. It is the middle indexed member in the sequence of fifteen such primes that divide the order of the Friendly Giant , the largest sporadic group: {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 41, 47, 59, 71}.
Janko groups and are the two-smallest of six pariah groups that are not subquotients of , which contain 19 as the largest prime number that divides their orders.
holds as standard generators that yield a semi-presentation where , while holds as standard generators , where .
is the dimensionality of the minimal faithful complex representation of O'Nan group — the second-largest after of like-representation in and largest amongst the six pariahs — whose value lies midway between primes (10939, 10949), the latter with a prime index of , which is the nineteenth tetrahedral number.
On the other hand, the Tits group , as the only non-strict group of Lie type that can loosely categorize as sporadic, has group order , whose prime factors (inclusive of powers) generate a sum equal to 54, which is the smallest non-trivial 19-gonal number.
In the Happy Family of sporadic groups, nineteen of twenty-six such groups are subquotients of the Friendly Giant, which is also its own subquotient. If the Tits group is indeed included as a group of Lie type, then there are nineteen classes of finite simple groups that are not sporadic groups.
Heegner number
19 is the sixth Heegner number. 67 and 163, respectively the 19th and 38th prime numbers, are the two largest Heegner numbers, of nine total.
The sum of the first six Heegner numbers 1, 2, 3, 7, 11, and 19 sum to the seventh member and fourteenth prime number, 43. All of these numbers are prime, aside from the unit. In particular, 163 is relevant in moonshine theory.
Science
The James Webb Space Telescope's optical elements are in an array of 19 hexagons, wherein 18 segmented primary mirrors focus light into a centered secondary mirror situated above the collecting mirrors, that in-turn reflects back onto the telescope's central imagers. It is a shape akin to the order-3 magic hexagon.
Religion
Islam
A group called United Submitter International claim the Quran has mathematical structure based on the number 19. The gematrical value of WAHD = 6+1+8+4=19, Wahd means 'One' (God) to the first verse (1:1), known as Bas-malah, consists of 19 Arabic letters or the Quran consists of 114 (19x6) surat etc.
Baháʼí Faith
In the Bábí and Baháʼí Faiths, a group of 19 is called a Váhid, a Unity (). The numerical value of this word in the Abjad numeral system is 19.
The Baháʼí calendar is structured such that a year contains 19 months of 19 days each (along with the intercalary period of Ayyám-i-Há), as well as a 19-year cycle and a 361-year (19x19) supercycle.
The Báb and his disciples formed a group of 19.
There were 19 Apostles of Bahá'u'lláh.
Celtic paganism
19 is a sacred number of the goddess Brigid because it is said to represent the 19-year cycle of the Great Celtic Year and the amount of time it takes the Moon to coincide with the winter solstice.
Music
Nineteen has been used as an alternative to twelve for a division of the octave into equal parts. This idea goes back to Salinas in the sixteenth century, and is interesting in part because it gives a system of meantone tuning, being close to 1/3 comma meantone. See 19 equal temperament.
Some organs use the 19th harmonic to approximate a minor third.
Literature
Stephen King's eight-book epic The Dark Tower saga employs the number 19 in books The Dark Tower: The Gunslinger, The Dark Tower V: Wolves of the Calla, The Dark Tower VI: Song of Susannah, The Dark Tower VII: The Dark Tower, and The Wind Through the Keyhole as a mysterious and important number. They refer to the "ka-tet of 19", "Directive Nineteen," many names add up to 19, 19 seems to permeate every aspect of Roland and his traveler's lives. In addition, the number ends up being a powerful key.
Games
Though the maximum score for a cribbage hand is 29, there is no combination of cards that adds up to 19 points. Many cribbage players, therefore, jokingly refer to a zero-point hand as "a 19 hand".
Age 19
In four countries, 19 is the age of majority.
In two countries, 19 is the minimum legal drinking age.
In three countries, 19 is the minimum legal smoking age.
The minimum age for the NBA draft is 19 years old.
In sports
In golf, the '19th hole' is the clubhouse bar and in match play, if there is a tie after 18 holes, an extra hole(s) is played. In miniature golf it is an extra hole on which the winner earns an instant prize.
References
External links
Number 19 at the Database of Number Correlations
Prime Curios for the number 19
Integers | 19 (number) | Mathematics | 2,385 |
41,713,359 | https://en.wikipedia.org/wiki/Process%20driven%20messaging%20service | A process driven messaging service (PDMS) is a service that is process oriented and exchanges messages/data calls. A PDMS is a service where jobs and triggers can be put together to create a workflow for a message.
Messaging platforms are considered key Internet infrastructure elements. A concept that once mainly encompassed email and IM has evolved to embrace complex multi-media email, instant messaging, and related fixed and mobile messaging infrastructure. Arguably, everything transmitted on the Internet and wireless telecommunication links are messages.
PDMS exchanges messages for the purpose of all kind of messages/data calls between systems, applications and or human beings that is based upon event-driven process chains.
Structure
A process driven messaging service is a service where jobs and triggers can be put together to create a workflow for a message and the workflow can be seen as a process.
A workflow is executed when a trigger is prompted. The trigger causes the activation of one or more jobs which can, in turn, execute more jobs. The workflow will still be active even when all jobs have been executed, but nothing occurs until it is re-triggered.
Workflows
A workflow in PDMS is used to wrap triggers and/or jobs together to accomplish a flow of actions and events that can be invoked over and over again without repeating the configuration. A workflow is a container. A workflow process is a container for a group of workflow statuses and actions, such as moving a record from one status to another. Other than triggers and jobs, it can contain groups or artifacts. The items that can be contained in the workflow are then available to all triggers and jobs within the workflow.
The concept of a workflow can be seen as a template for either part of, or a whole, business process. Workflows can be triggered for a number of different reasons, an example of which could be if something were to happen in the domain or there were to be an explicit call to invoke.
The workflow will be in a state awaiting execution when the workflow, its triggers, and its jobs are active.
When created, workflows require the last job to be added first, meaning jobs are to be listed in reverse order of execution. Jobs and triggers also require the reverse sequential listing of orders when created.
Jobs
A job creates something such as a task (e. g., sending a message) or affects Standard Objects (e.g. way metadata in a unit). It is a task describing what the system should do and can be several things. A job, when activated, can lead to the execution of another job (for instance: message delivery). It represents what a system does with the data, an activity within the system domain.
Jobs provide a means to encapsulate a process. A Job is a configuration representing input options, the steps in the process, a filter expression that matches the nodes where those steps will execute, and execution control parameters that specify if steps are run in parallel. One might find certain command executions are done repeatedly, and perhaps, represent what has become a routine procedure. Routine processes need to be encapsulated and become the basis for other routine procedures.
Triggers
A trigger—what starts/executes a workflow—prompts the execution of actions. The object's components that define business logic and behavior are called triggers. You can create and configure any number of triggers to perform automated and programmatic validation, notification, data manipulation, and other activities upon record creation, updating, and deletion.
Processes
A process starts at some point in the system. For example, when a trigger executes an instance of a workflow.
A process driven messaging service is often used when managing a more or less complex business processes.
With a well developed process driven messaging platform, all triggers and jobs can be exposed in a public API (application programming interface), and it will then be possible to create the process in the API.
Technology/programming
PDMS is based upon Event-Driven Architecture whereas the architectural pattern may be applied by the design and implementation of applications and systems which transmit events among loosely coupled software components and services. Unlike traditional information systems which work by issuing requests and waiting for responses, event-driven systems are designed to process events as they occur, allowing the system to observe, react dynamically, and issue personalized data depending on the recipient and situation.
Applicable areas
Areas where PDMS can be used are System to System, A2P with the difference that other message types can be included in the PDMS, Application to Application, System to Person, M2M and all kinds of messages/data calls between systems, applications and/or people based upon event-driven processes.
See also
Architectural pattern
Application-to-person (A2P) SMS
Critical Internet infrastructure
Event-driven architecture
Internet messaging platform
Loose coupling
Machine to machine (M2M)
Process mining
Service (systems architecture)
Workflow
References
Message transfer agents
Enterprise application integration
Text messaging
Mobile telecommunications standards | Process driven messaging service | Technology | 1,014 |
20,341,296 | https://en.wikipedia.org/wiki/Vatalanib | Vatalanib (INN, codenamed PTK787 or PTK/ZK) is a small molecule protein kinase inhibitor that inhibits angiogenesis. It is being studied as a possible treatment for several types of cancer, particularly cancer that is at an advanced stage or has not responded to chemotherapy. Vatalanib is orally active, which is to say it is effective when taken by mouth.
Vatalanib is being developed by Bayer Schering and Novartis. It inhibits all known VEGF receptors, as well as platelet-derived growth factor receptor-beta and c-kit, but is most selective for VEGFR-2.
Development
Vatalanib was discovered through high-throughput screening. It has been extensively investigated in Phase I, II and III clinical trials. Two large, randomized controlled Phase III trials have studied the effect of adding vatalanib to the FOLFOX chemotherapy regimen in people with metastatic colorectal cancer: CONFIRM-1, whose participants had not yet received any treatment for their cancer; and CONFIRM-2, in which participants had received first-line treatment with irinotecan and fluoropyrimidines. Vatalanib produced no significant improvement in overall survival (the primary endpoint of the studies), although it did significantly increase progression-free survival in CONFIRM-2. Both trials found that progression-free survival was improved in people with high levels of lactate dehydrogenase, an enzyme used as a marker of tissue breakdown; the reasons for and implications of this difference are still unclear.
Adverse effects
The adverse effects of vatalanib appear similar to those of other VEGF inhibitors. In the CONFIRM trials, the most common side effects were high blood pressure, gastrointestinal upset (diarrhea, nausea, and vomiting), fatigue, and dizziness.
Notable users
Patrick Swayze, a popular actor in the 1980s who starred in such films as Dirty Dancing and Road House was given this drug when he was diagnosed with Stage IV Pancreatic Cancer in 2008. Doctors hoped the drug would cut off blood supply to the tumor. Despite this, Swayze died on September 14, 2009, 20 months after being diagnosed.
References
External links
Ongoing and completed clinical trials of vatalanib at ClinicalTrials.gov (U.S. National Institutes of Health)
Angiogenesis inhibitors
Tyrosine kinase inhibitors
Experimental cancer drugs | Vatalanib | Biology | 500 |
6,904,987 | https://en.wikipedia.org/wiki/Virtual%20heritage | Virtual heritage or cultural heritage and technology is the body of works dealing with information and communication technologies and their application to cultural heritage, such as virtual archaeology. It aims to restore ancient cultures as real (virtual) environments where users can immerse.
Virtual heritage and cultural heritage have independent meanings: cultural heritage refers to sites, monuments, buildings and objects "with historical, aesthetic, archaeological, scientific, ethnological or anthropological value", whereas virtual heritage refers to instances of these within a technological domain, usually involving computer visualization of artefacts or virtual reality environments.
First use
The first use of virtual heritage as a museum exhibit, and the derivation of the name virtual tour, was in 1994 as a museum visitor interpretation, providing a 'walk-through' of a 3D reconstruction of Dudley Castle in England as it was in 1550.
This consisted of a computer controlled laserdisc based system designed by British-based engineer Colin Johnson. It is a little-known fact that one of the first users of virtual heritage was Queen Elizabeth II, when she officially opened the visitor centre in June 1994.
Because the Queen's officials had requested titles, descriptions and instructions of all activities, the system was named 'Virtual Tour', being a cross between virtual reality and royal tour.
Projects
One technology that is frequently employed in virtual heritage applications is augmented reality (AR), which is used to provide on-site reconstructions of archaeological sites or artefacts. An example is the lifeClipper project, a Swiss commercial tourism and mixed reality urban heritage project. Using HMD technology, users walking the streets of Basel can see cultured AR video characters and objects as well as oddly-shaped stencils.
Many virtual heritage projects focus on the tangible aspects of cultural heritage, for example 3D modelling, graphics and animation. In doing so, they often overlook the intangible aspects of cultural heritage associated with objects and sites, such as stories, performances and dances. The tangible aspects of cultural heritage are not inseparable from the intangible and one method for combining them is the use of virtual heritage serious games, such as the 'Digital Songlines' and 'Virtual Songlines' which modified computer game technology to preserve, protect and present the cultural heritage of Aboriginal Australian Peoples. There have been numerous applications of digital models being used to engage the public and encourage involvement in built heritage activities and discourse.
Place-Hampi is another example of a virtual heritage project. It applies co-evolutionary systems to show a cultural presence using stereoscopic rendering of the landscape of Hampi landscape, a UNESCO World Heritage Site in Karnataka, India.
See also
CyArk
Computational archaeology
Digital heritage
References
Further reading
Michael Falser, Monica Juneja (eds.). 'Archaeologizing' Heritage? Transcultural Entanglements between Local Social Practices and Global Virtual Realities. Heidelberg, New York: Springer (2013), .
External links
Cultural heritage
Virtual reality
Digital humanities | Virtual heritage | Technology | 589 |
951,352 | https://en.wikipedia.org/wiki/Carbendazim | Carbendazim is a fungicide, a member benzimidazole fungicides. It is a metabolite of benomyl.
The fungicide is used to control plant diseases in cereals and fruits, including citrus, bananas, strawberries, macadamia nuts, pineapples, and pomes. A 4.7% solution of carbendazim hydrochloride, sold as Eertavas, is marketed as a treatment for Dutch elm disease.
Other uses
It is also employed as a casting worm control agent in amenity turf situations such as golf greens, tennis courts etc. and in some countries is licensed for that use only.
Safety, regulation, controversy
High doses of carbendazim destroy the testicles of laboratory animals.
Maximum pesticide residue limits (MRLs) for fresh produce in the EU are between 0.1 and 0.7 mg/kg with the exception of loquat fruits, which is set at 2 mg/kg. The limits for more commonly consumed citrus and pome fruits are between 0.1 and 0.2 mg/kg.
Use of this fungicide on macadamia plantations has proven controversial in Queensland.
References
External links
International Chemical Safety Card
Acetylcholinesterase inhibitors
Fungicides
Endocrine disruptors
Benzimidazoles
Carbamates
Spermatotoxicants
Testicular toxicants
Methyl esters | Carbendazim | Chemistry,Biology | 289 |
209,440 | https://en.wikipedia.org/wiki/Perseids | The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle that are usually visible from mid-July to late-August. The meteors are called the Perseids because they appear from the general direction of the constellation Perseus and in more modern times have a radiant bordering on Cassiopeia and Camelopardalis.
Etymology
The name is derived from the word Perseidai (), the sons of Perseus in Greek mythology.
Characteristics
The stream of debris is called the Perseid cloud and stretches along the orbit of the comet Swift–Tuttle. The cloud consists of particles ejected by the comet as it travels on its 133-year orbit. Most of the particles have been part of the cloud for around a thousand years. However, there is also a relatively young filament of dust in the stream that was pulled off the comet in 1865, which can give an early mini-peak the day before the maximum shower. The dimensions of the cloud in the vicinity of the Earth are estimated to be approximately 0.1 astronomical units (AU) across and 0.8 AU along the Earth's orbit, spread out by annual interactions with the Earth's gravity.
The shower is visible from mid-July each year, with the peak in activity between 9 and 14 August, depending on the particular location of the stream. During the peak, the rate of meteors reaches 60 or more per hour. They can be seen all across the sky; however, because of the shower's radiant in the constellation of Perseus, the Perseids are primarily visible in the Northern Hemisphere. As with many meteor showers the visible rate is greatest in the pre-dawn hours, since more meteoroids are scooped up by the side of the Earth moving forward into the stream, corresponding to local times between midnight and noon, as can be seen in the accompanying diagram. While many meteors arrive between dawn and noon, they are usually not visible due to daylight. Some can also be seen before midnight, often grazing the Earth's atmosphere to produce long bright trails and sometimes fireballs. Most Perseids burn up in the atmosphere while at heights above .
Peak times
Historical observations and associations
Some Catholics refer to the Perseids as the "tears of Saint Lawrence", suspended in the sky but returning to Earth once a year on August 10, the canonical date of that saint's martyrdom in 258 AD. The saint is said to have been burned alive on a gridiron. His manner of death is almost certainly the origin of the Mediterranean folk legend claiming that the shooting stars are the sparks of Saint Lawrence's martyrdom. The legend holds that during the night of August 9 to 10, cooled embers appear in the ground under plants; these embers are known as the "coal of Saint Lawrence."
The transition in favor of the Catholic saint and his feast day on August 10, moving away from pagan gods and their festivals — a process known as Christianization — was facilitated by the phonetic assonance of the Latin name Laurentius with Acca Larentia, a goddess previously celebrated during the summer period alongside Priapus, as a fertility deity. Among the Romans, it was believed that the trails of the Perseids represented the benevolent rain of Priapus' seed. In this context, the god's cosmogonic phallus acted as a life-giver, blessing the fields and promoting fertility. During the same period, phallic processions and other sexual rites were common. Christianity, which had a different relationship with sexuality and generativity compared to Greco-Roman culture, replaced this sexual connotation with a reference to martyrdom.
In 1836 Adolphe Quetelet wrote: J'ai cru remarquer aussi une fréquence plus grande de ces météores au mois d'août (du 8 au 15) "I think I noticed also a greater frequency of these meteors in the month of August (from 8 to 15)." After studying historical records, he predicted a peak on 10 August. He then wrote to other astronomers, who confirmed this prediction on the night of 10 August 1837. Quetelet missed the shower due to bad weather.
In 1866, after the perihelion passage of Swift-Tuttle in 1862, the Italian astronomer Giovanni Virginio Schiaparelli discovered the link between meteor showers and comets. The finding is contained in an exchange of letters with Angelo Secchi.
In popular culture
In his 2006 novel Against the Day, American novelist Thomas Pynchon refers to the Perseid meteor shower being watched by three characters west of the Dolores Valley after playing a game of tarot.
In the TV series Curious George, season 7 episode 1b, George and his friends Allie and Bill hunt for the Perseids, which they believe are creatures that look like purses. At the end of the episode, Allie's grandfather Mr. Renkins says that the Perseids is a meteor shower happening in early August.
John Denver's song "Rocky Mountain High" references the showers with the lyric, "I've seen it raining fire in the sky."
See also
Leonids, associated with the comet Tempel–Tuttle
Asteroid impact prediction
Earth-grazing fireball
List of asteroid close approaches to Earth
Meteoroid
References
General and cited references
Littman, Mark, The Heavens on Fire: The Great Leonid Meteor Storms, Cambridge, Cambridge University Press, 1998. . Chapter 6, "The Discovery of the August Meteors", pp. 83–100.
External links
Where to see the Perseids and public stargazing events in the UK (Go Stargazing)
Worldwide viewing times for the 2016 Perseids meteor shower
How to see the Perseid meteor shower in 2024 (Paul Sutherland)
How to photograph a meteor shower (Skymania)
Perseid Observing Conditions (The International Project for Radio Meteor Observation)
2014 Perseids Radio results (RMOB)
Perseid Visibility Map (2014 NASA Meteoroid Environment Office)
2009 Perseid Meteor Fireball
NASA website on the Perseid shower of 2009
Sky & Telescope Magazine – Perseids at Their Prime
2012 Image of Perseids emanating from the radiant
What are the perseids?
July
August
Meteor showers
Perseus (constellation) | Perseids | Astronomy | 1,296 |
3,984,464 | https://en.wikipedia.org/wiki/Fructan | A fructan is a polymer of fructose molecules. Fructans with a short chain length are known as fructooligosaccharides. Fructans can be found in over 12% of the angiosperms including both monocots and dicots such as agave, artichokes, asparagus, leeks, garlic, onions (including spring onions), yacón, jícama, barley and wheat.
Fructans also appear in grass, with dietary implications for horses and other grazing animals (Equidae).
Types
Fructans are built up of fructose residues, normally with a sucrose unit (i.e. a glucose–fructose disaccharide) at what would otherwise be the reducing terminus. The linkage position of the fructose residues determine the type of the fructan. There are five types of fructans.
Linkage normally occurs at one of the two primary hydroxyls (OH-1 or OH-6), and there are two basic types of simple fructan:
1-linked: in inulin, the fructosyl residues are linked by β-2,1-linkages
6-linked: in levan and phlein, the fructosyl residues are linked by β-2,6-linkages
A third type of fructans, the graminin type, contains both β-2,1-linkages and β-2,6-linkages.
Two more types of fructans are more complex: they are formed on a 6G-kestotriose backbone where elongations occur on both sides of the molecule. Again two types are discerned:
neo-inulin type (also called "inulin neoseries"): predominant β-2,1-linkages
neo-levan type (also called "levan neoseries"): predominant β-2,6-linkages
Functions
Fructans are important storage polysaccharides in the stems of many species of grasses and confer a degree of freezing tolerance. A notable exception is rice, which is unable to synthesise fructans.
In barley, fructan accumulates in the cell vacuoles and acts as a carbon sink within the cell to facilitate photosynthesis. Fructan reserves are transported to the reproductive tissue during grain filling, and to the vegetative tissues during periods of growth.
Chicory inulin-type fructans are used mainly as the raw materials for industrial production of fructans as food ingredients. Use in the food industry is based on the nutritional and technological properties of fructans as a prebiotic dietary fiber.
Fructan content of various foods
See also
Notes
References
Sugar – Chemical, Biological and Nutritional Aspects of Sucrose. John Yudkin, Jack Edelman and Leslie Hough (1971, 1973). The Butterworth Group.
Polysaccharides
Prebiotics (nutrition) | Fructan | Chemistry | 634 |
13,358,411 | https://en.wikipedia.org/wiki/Personal%20health%20application | Personal health applications (PHA) are tools and services in medical informatics which utilizes information technologies to aid individuals to create their own personal health information. These next generation consumer-centric information systems help improve health care delivery, self-management and wellness by providing clear and complete information, which increases understanding, competence and awareness. Personal health applications are part of the Medicine 2.0 movement.
Definition
Personal Health Application is an electronic tool of storing, managing and sharing health information in illness and wellness by an individual in a secure and confidential environment.
Benefits
Most people do not carry medical records when they leave home. They do not realize that in an emergency these medical records can make a big difference; additionally, it is hard to predict when an emergency might occur. In fact, they could save a life. Previous medications, history of allergy to medications, and other significant medical or surgical history can help a health professional through PHA tools to optimize treatment.
A Personal Health Application (PHA) tool contains a patient's personal data (name, date of birth and other demographic details). It also includes a patient's diagnosis or health condition and details about the various treatment/assessments delivered by health professionals during an episode of care from a health care provider. It contains an individual's health-related information accumulated during an entire lifetime.
See also
eHealth
mHealth
Personal health record
References
Health informatics | Personal health application | Biology | 287 |
2,819,178 | https://en.wikipedia.org/wiki/IEEE%20802.1D | IEEE 802.1D is the Ethernet MAC bridges standard which includes bridging, Spanning Tree Protocol and others. It is standardized by the IEEE 802.1 working group. It includes details specific to linking many of the other 802 projects including the widely deployed 802.3 (Ethernet), 802.11 (Wireless LAN) and 802.16 (WiMax) standards.
Bridges using virtual LANs (VLANs) have never been part of 802.1D, but were instead specified in separate standard, 802.1Q originally published in 1998.
By 2014, all the functionality defined by IEEE 802.1D has been incorporated into either IEEE 802.1Q-2014 (Bridges and Bridged Networks) or IEEE 802.1AC (MAC Service Definition). 802.1D is expected to be officially withdrawn in 2022.
Publishing history:
1990 — Original publication (802.1D-1990).
1993 — standard ISO/IEC 10038:1993.
1998 — Revised version (802.1D-1998, ISO/IEC 15802-3:1998), incorporating the extensions P802.1p, P802.12e, 802.1j-1996 and 802.6k-1992.
2004 — Revised version (802.1D-2004), incorporating the extensions 802.11c-1998, 802.1t-2001, 802.1w-2001, and removing the original Spanning Tree Protocol, instead incorporating the Rapid Spanning Tree Protocol (RSTP) from 802.1w-2001.
Amendments to 802.1D-2004:
2004 — Small amendment (802.17a-2004) to add in 802.17 bridging support.
2007 — Small amendment (802.16k-2007) to add in 802.16 bridging support.
2012 — Shortest Path Bridging (IEEE 802.1aq-2012, amendment to 802.1Q-2011).
See also
Multiple Spanning Tree Protocol
Spanning Tree Protocol
TRILLTransparent Interconnection of Lots of Links
References
802.1D-2004 - IEEE Standard for Local and metropolitan area networks: Media Access Control (MAC) Bridges
802.1D Status
IEEE 802.01D
Ethernet standards | IEEE 802.1D | Technology | 457 |
25,183,976 | https://en.wikipedia.org/wiki/Convolution%20for%20optical%20broad-beam%20responses%20in%20scattering%20media | Photon transport theories in Physics, Medicine, and Statistics (such as the Monte Carlo method), are commonly used to model light propagation in tissue. The responses to a pencil beam incident on a scattering medium are referred to as Green's functions or impulse responses. Photon transport methods can be directly used to compute broad-beam responses by distributing photons over the cross section of the beam. However, convolution can be used in certain cases to improve computational efficiency.
General convolution formulas
In order for convolution to be used to calculate a broad-beam response, a system must be time invariant, linear, and translation invariant. Time invariance implies that a photon beam delayed by a given time produces a response shifted by the same delay. Linearity indicates that a given response will increase by the same amount if the input is scaled and obeys the property of superposition. Translational invariance means that if a beam is shifted to a new location on the tissue surface, its response is also shifted in the same direction by the same distance. Here, only spatial convolution is considered.
Responses from photon transport methods can be physical quantities such as absorption, fluence, reflectance, or transmittance. Given a specific physical quantity, G(x,y,z), from a pencil beam in Cartesian space and a collimated light source with beam profile S(x,y), a broad-beam response can be calculated using the following 2-D convolution formula:
Similar to 1-D convolution, 2-D convolution is commutative between G and S with a change of variables and :
Because the broad-beam response has cylindrical symmetry, its convolution integrals can be rewritten as:
where . Because the inner integration of Equation 4 is independent of z, it only needs to be calculated once for all depths. Thus this form of the broad-beam response is more computationally advantageous.
Common beam profiles
Gaussian beam
For a Gaussian beam, the intensity profile is given by
Here, R denotes the radius of the beam, and S0 denotes the intensity at the center of the beam. S0 is related to the total power P0 by
Substituting Eq. 5 into Eq. 4, we obtain
where I0 is the zeroth-order modified Bessel function.
Top-hat beam
For a top-hat beam of radius R, the source function becomes
where S0 denotes the intensity inside the beam. S0 is related to the total beam power P0 by
Substituting Eq. 8 into Eq. 4, we obtain
where
Errors in numerical evaluation
First interactions
First photon-tissue interactions always occur on the z axis and hence contribute to the specific absorption or related physical quantities as a Dirac delta function. Errors will result if absorption due to the first interactions is not recorded separately from absorption due to subsequent interactions. The total impulse response can be expressed in two parts:
where the first term results from the first interactions and the second, from subsequent interactions.
For a Gaussian beam, we have
For a top-hat beam, we have
Truncation error
For a top-hat beam, the upper integration limits may be bounded by rmax, such that r ≤ rmax − R. Thus, the limited grid coverage in the r direction does not affect the convolution. To convolve reliably for physical quantities at r in response to a top-hat beam, we must ensure that rmax in photon transport methods is large enough that r ≤ rmax − R holds.
For a Gaussian beam, no simple upper integration limits exist because it theoretically extends to infinity. At r >> R, a Gaussian beam and a top-hat beam of the same R and S0 have comparable convolution results. Therefore, r ≤ rmax − R can be used approximately for Gaussian beams as well.
Implementation of convolution
There are two common methods used to implement discrete convolution: the definition of convolution and fast Fourier transformation (FFT and IFFT) according to the convolution theorem. To calculate the optical broad-beam response, the impulse response of a pencil beam is convolved with the beam function. As shown by Equation 4, this is a 2-D convolution. To calculate the response of a light beam on a plane perpendicular to the z axis, the beam function (represented by a b × b matrix) is convolved with the impulse response on that plane (represented by an a × a matrix). Normally a is greater than b. The calculation efficiency of these two methods depends largely on b, the size of the light beam.
In direct convolution, the solution matrix is of the size (a + b − 1) × (a + b − 1). The calculation of each of these elements (except those near boundaries) includes b × b multiplications and b × b − 1 additions, so the time complexity is O[(a + b)2b2]. Using the FFT method, the major steps are the FFT and IFFT of (a + b − 1) × (a + b − 1) matrices, so the time complexity is O[(a + b)2 log(a + b)]. Comparing O[(a + b)2b2] and O[(a + b)2 log(a + b)], it is apparent that direct convolution will be faster if b is much smaller than a, but the FFT method will be faster if b is relatively large.
See also
Radiative transfer equation and diffusion theory for photon transport in biological tissue
Monte Carlo method
Monte Carlo method for photon transport
Links to other Monte Carlo resources
Optical Imaging Laboratory at Washington University in St. Louis (MCML)
Oregon Medical Laser Center
References
L.-H. Wang and H.-I. Wu. Biomedical Optics: Principles and Imaging. Wiley 2007.
L.-H. Wang, S. L. Jacques, and L.-Q. Zheng, "Monte Carlo modeling of photon transport in multi-layered tissues," Computer Methods and Programs in Biomedicine 47, 131–146 (1995).
L.-H. Wang, S. L. Jacques, and L.-Q. Zheng, "Convolution for responses to a finite diameter photon beam incident on multi-layered tissues," Computer Methods and Programs in Biomedicine 54, 141–150 (1997). Download article.
Scattering theory | Convolution for optical broad-beam responses in scattering media | Chemistry | 1,362 |
5,971,868 | https://en.wikipedia.org/wiki/Cadmium%20bromide | Cadmium bromide is the inorganic compound with the formula CdBr2. It is a white hygroscopic solid. It also can be obtained as a mono- and tetrahydrate. It has few applications.
Preparation and structure
Cadmium bromide is prepared by heating cadmium with bromine vapor. The tetrahydrate has been obtained by crystallization of the dibromide from aqueous solution. At 3.04 g/cm3, it is much less dense than the anhydrous material. According to X-ray crystallography, the tetrahydrate is a polymer of CdBr2(H2O)2 with bridging bromide ligands. There are two interstitial water molecules
References
Cadmium compounds
Bromides
Metal halides
Photographic chemicals | Cadmium bromide | Chemistry | 169 |
316,904 | https://en.wikipedia.org/wiki/Ehrhart%20polynomial | In mathematics, an integral polytope has an associated Ehrhart polynomial that encodes the relationship between the volume of a polytope and the number of integer points the polytope contains. The theory of Ehrhart polynomials can be seen as a higher-dimensional generalization of Pick's theorem in the Euclidean plane.
These polynomials are named after Eugène Ehrhart who studied them in the 1960s.
Definition
Informally, if is a polytope, and is the polytope formed by expanding by a factor of in each dimension, then is the number of integer lattice points in .
More formally, consider a lattice in Euclidean space and a -dimensional polytope in with the property that all vertices of the polytope are points of the lattice. (A common example is and a polytope for which all vertices have integer coordinates.) For any positive integer , let be the -fold dilation of (the polytope formed by multiplying each vertex coordinate, in a basis for the lattice, by a factor of ), and let
be the number of lattice points contained in the polytope . Ehrhart showed in 1962 that is a rational polynomial of degree in , i.e. there exist rational numbers such that:
for all positive integers .
The Ehrhart polynomial of the interior of a closed convex polytope can be computed as:
where is the dimension of . This result is known as Ehrhart–Macdonald reciprocity.
Examples
Let be a -dimensional unit hypercube whose vertices are the integer lattice points all of whose coordinates are 0 or 1. In terms of inequalities,
Then the -fold dilation of is a cube with side length , containing integer points. That is, the Ehrhart polynomial of the hypercube is . Additionally, if we evaluate at negative integers, then
as we would expect from Ehrhart–Macdonald reciprocity.
Many other figurate numbers can be expressed as Ehrhart polynomials. For instance, the square pyramidal numbers are given by the Ehrhart polynomials of a square pyramid with an integer unit square as its base and with height one; the Ehrhart polynomial in this case is .
Ehrhart quasi-polynomials
Let be a rational polytope. In other words, suppose
where and (Equivalently, is the convex hull of finitely many points in ) Then define
In this case, is a quasi-polynomial in . Just as with integral polytopes, Ehrhart–Macdonald reciprocity holds, that is,
Examples of Ehrhart quasi-polynomials
Let be a polygon with vertices (0,0), (0,2), (1,1) and (, 0). The number of integer points in will be counted by the quasi-polynomial
Interpretation of coefficients
If is closed (i.e. the boundary faces belong to ), some of the coefficients of have an easy interpretation:
the leading coefficient, , is equal to the -dimensional volume of , divided by (see lattice for an explanation of the content or covolume of a lattice);
the second coefficient, , can be computed as follows: the lattice induces a lattice on any face of ; take the -dimensional volume of , divide by , and add those numbers for all faces of ;
the constant coefficient, , is the Euler characteristic of . When is a closed convex polytope, .
The Betke–Kneser theorem
Ulrich Betke and Martin Kneser established the following characterization of the Ehrhart coefficients. A functional defined on integral polytopes is an and translation invariant valuation if and only if there are real numbers such that
Ehrhart series
We can define a generating function for the Ehrhart polynomial of an integral -dimensional polytope as
This series can be expressed as a rational function. Specifically, Ehrhart proved (1962) that there exist complex numbers , , such that the Ehrhart series of is
Additionally, Richard P. Stanley's non-negativity theorem states that under the given hypotheses, will be non-negative integers, for .
Another result by Stanley shows that if is a lattice polytope contained in , then for all . The -vector is in general not unimodal, but it is whenever it is symmetric, and the polytope has a regular unimodular triangulation.
Ehrhart series for rational polytopes
As in the case of polytopes with integer vertices, one defines the Ehrhart series for a rational polytope. For a d-dimensional rational polytope , where is the smallest integer such that is an integer polytope ( is called the denominator of ), then one has
where the are still non-negative integers.
Non-leading coefficient bounds
The polynomial's non-leading coefficients in the representation
can be upper bounded:
where is a Stirling number of the first kind. Lower bounds also exist.
Toric variety
The case and of these statements yields Pick's theorem. Formulas for the other coefficients are much harder to get; Todd classes of toric varieties, the Riemann–Roch theorem as well as Fourier analysis have been used for this purpose.
If is the toric variety corresponding to the normal fan of , then defines an ample line bundle on , and the Ehrhart polynomial of coincides with the Hilbert polynomial of this line bundle.
Ehrhart polynomials can be studied for their own sake. For instance, one could ask questions related to the roots of an Ehrhart polynomial. Furthermore, some authors have pursued the question of how these polynomials could be classified.
Generalizations
It is possible to study the number of integer points in a polytope if we dilate some facets of but not others. In other words, one would like to know the number of integer points in semi-dilated polytopes. It turns out that such a counting function will be what is called a multivariate quasi-polynomial. An Ehrhart-type reciprocity theorem will also hold for such a counting function.
Counting the number of integer points in semi-dilations of polytopes has applications in enumerating the number of different dissections of regular polygons and the number of non-isomorphic unrestricted codes, a particular kind of code in the field of coding theory.
See also
Quasi-polynomial
Stanley's reciprocity theorem
References
Further reading
. Introduces the Fourier analysis approach and gives references to other related articles.
.
Figurate numbers
Polynomials
Lattice points
Polytopes | Ehrhart polynomial | Mathematics | 1,339 |
13,904,544 | https://en.wikipedia.org/wiki/New%20Zealand%20Food%20Safety |
New Zealand Food Safety (NZFS), or Haumaru Kai Aotearoa, was the New Zealand government body responsible for food safety, and is the controlling authority for imports and exports of food and food-related products. In April 2012 it was merged into the Ministry for Primary Industries.
The NZFSA administered legislation covering:
food for sale in New Zealand
primary processing of animal products and official assurances related to their export
exports of plant products and the controls surrounding registration, and
use of agricultural compounds and veterinary medicines.
In July 2007 the NZFSA was separated from the Ministry of Agriculture and Forestry to form a new Public Service Department. On 1 July 2010, the New Zealand Food Safety Authority (NZFSA) was amalgamated back into the Ministry of Agriculture and Forestry.
Food Bill 160-2
Food Bill 160-2 was introduced on 26 May 2010 to make some fundamental changes to New Zealand's domestic food regulatory regime. Significantly, for an export-led economic recovery for New Zealand, the domestic food regulatory regime is the platform for exports. The New Zealand domestic standard is used as the basis for negotiating equivalence arrangements with trading partners. This minimizes the excessive importing country requirements that may be imposed but which do not go to food safety. If passed into law and fully implemented, it would replace the Food Act 1981 and the Food Hygiene Regulations 1974. Food Bill will also make consequential amendments to the Animal Products Act 1999 and the Wine Act 2003 to improve the interface of regulatory processes across food sectors.
MAF (through NZFSA) managed New Zealand's participation in Codex Alimentarius and set strategic priorities which ensure that Codex standards have the widest possible application.
See also
Food safety in New Zealand
Food Standards Australia New Zealand
Food Act 1981 - New Zealand
Food Act 2014 - New Zealand
References
External links
New Zealand Food Safety Authority
Government agencies of New Zealand
Regulators of biotechnology products
Food safety organizations
Food safety in New Zealand
Medical and health organisations based in New Zealand
Regulation in New Zealand | New Zealand Food Safety | Biology | 405 |
1,834,194 | https://en.wikipedia.org/wiki/Kick%20start | Kick start is a method of starting an internal combustion engine (usually that of a motorcycle) by pushing a ratcheting lever with the rider's foot. Kick start mechanisms were almost universally a part of motorcycle engines before the mid-1970s, and were phased out of production over the next twenty years or so as electric starters became standard equipment. There are still some motorcycles produced that have both kick and electric starters.
Many mopeds and scooters also carry both a kick start and an electric start, the former being useful in case the latter fails, as scooter and moped batteries tend to be smaller and, as a result, run down much faster than other forms of automotive batteries. Also, it is usually not possible to push start a moped or scooter with automatic transmission.
Larger motorcycles featured a manual compression release mechanism that made starting easier while modern units did this automatically through a cable attached to the kick start lever.
Today, dedicated off-road motorcycles and many ATVs use kick start systems, to avoid the weight of electric starters. The majority of the inexpensive two-wheelers and sometimes three-wheelers in developing countries, also use kick start systems.
Operation
Before starting, kickstart levers are generally unfolded from the side of the motorcycle so that the rider can clear the side of the engine as it rotates. As the lever begins to descend under the rider's foot, the rachet engages a gear linked to the crankshaft causing it to spin past top dead center so that an ignition spark can ignite the compressed fuel mixture. Upon starting, the rachet disengages and the rider folds the lever back.
On some large displacement twins or singles, 'kickback' can occur if the fuel ignites before the piston reaches top dead center. This causes the crank to spin backwards and can be painful for the rider as the lever kicks back on their foot.
The first kick start motorcycle was a British Scott Motorcycle two-stroke twin manufactured in 1910.
Some scooters have kick starters with a tendency not to always work, if not performed correctly. Some manufacturers have also included kick starters in their models, only for a purpose of introducing apparent convenience for ignition, as opposed to offering a reliable alternative for an electric starter.
See also
Jump start
References
Motorcycle engines
Starting systems | Kick start | Technology | 469 |
34,122,362 | https://en.wikipedia.org/wiki/Fluence%20response | Both fluence rates and irradiance of light are important signals for plants and are detected by phytochrome. Exploiting different modes of photoreversibility in this molecule allow plants to respond to different levels of light. There are three main types of fluence rate governed responses that are brought about by different levels of light.
Very low fluence responses
As the name would suggest this type of response is triggered by very low levels of light and is thought to be mediated by phytochrome A. It can be initiated by fluences as low as 0.0001μmol/m2 up to about 0.05μmol/m2. Germination of Arabidopsis can be induced with very low levels of red light, as can oat seedlings. Such low levels of light are sufficient for inducing this response, since they only convert 0.02% of the phytochrome to its active form. The backward reaction by far red light is only 98% efficient making the conversion non-photoreversible and allowing the response to proceed. VLFRs can also be induced by making up the required fluence by brief flashes of light. Since this depends on light levels and time it is known as the law of reciprocity.
Low fluence responses
These responses require at least 1μmol/m2 to be initiated and become saturated at about 1000μmol/m2. Unlike VLFRs, these responses are photoreversible. This was shown by exposing lettuce seed to a brief flash of red light causing germination. It was then shown, if this red flash was followed by a flash of far red light, germination was again inhibited. LFRs also follow the law of reciprocity. Other examples of LFRs include leaf de-etiolation and enhancement of rate of chlorophyll production.
High-irradiance responses
HIRs require long exposure to relatively high light levels. The degree of response will depend on the level of light. They are characterised by the fact that they do not follow the law of reciprocity and depend on the rate of photons hitting the leaf surface, as opposed to the total light levels. This means that neither long exposure to dim levels of light nor very bright flashes of light are enough to trigger these responses. HIR does not show red and far red photoreversibility and does not obey the law of reciprocity.
References
Physical quantities
Radiometry
Photosynthesis | Fluence response | Physics,Chemistry,Mathematics,Engineering,Biology | 513 |
11,793,054 | https://en.wikipedia.org/wiki/Claviceps%20zizaniae | Claviceps zizaniae is a plant pathogen that causes ergot in the wild rice species Zizania aquatica and Z. palustris. Originally described in 1920 as Spermoedia zizaniae by Faith Fyles, it was transferred to Claviceps in 1959 by Maria E. Pantidou. The new combination, however, was not published validly as Pantidou "failed to provide a full and direct reference to the place of publication". The binomial was published validly by Scott Redhead and colleagues in 2009.
References
Fungi described in 1920
Fungal plant pathogens and diseases
Monocot diseases
Clavicipitaceae
Fungus species | Claviceps zizaniae | Biology | 137 |
42,909,270 | https://en.wikipedia.org/wiki/Anton%E2%80%93Schmidt%20equation%20of%20state | The Anton–Schmidt equation is an empirical equation of state for crystalline solids, e.g. for pure metals or intermetallic compounds.
Quantum mechanical investigations of intermetallic compounds show that the dependency of the pressure under isotropic deformation can be described empirically by
.
Integration of leads to the equation of state for the total energy. The energy required to compress a solid to volume is
which gives
.
The fitting parameters and are related to material properties, where
is the bulk modulus at equilibrium volume .
correlates with the Grüneisen parameter .
However, the fitting parameter does not reproduce the total energy of the free atoms.
The total energy equation is used to determine elastic and thermal material constants in quantum chemical simulation packages.
The equation of state has been used in cosmological contexts to describe the dark energy dynamics. However its use has been recently criticized since it appears disfavored than simpler equations of state adopted for the same purpose.
See also
Murnaghan equation of state
Rose–Vinet equation of state
Birch–Murnaghan equation of state
References
Solid mechanics
Equations of state | Anton–Schmidt equation of state | Physics | 225 |
26,592,619 | https://en.wikipedia.org/wiki/CoRoT-9b | CoRoT-9b is an exoplanet orbiting the star CoRoT-9, approximately 1500 light years away in the constellation Serpens. CoRoT-9b's distance of nearest approach to its parent star of approximately 0.36 AU was the largest of all known transiting planets at the time of its discovery, with an orbital period of 95 days. The transit of this planet lasts 8 hours. The planet is at a distance from its star where there is a strong increase in albedo as the temperature decreases, because of the condensation of reflective water clouds in the atmosphere. This suggests its atmosphere may be locked into one of two states: a cloudless state with temperatures between and , or covered in water clouds with a temperature in the range to .
Discovery
CoRoT-9b was discovered by combining observations from the CoRoT satellite, which looks for a small dip in starlight as a planet passes in front of its parent star, and radial velocity measurements from the European Southern Observatory's High Accuracy Radial velocity Planet Searcher (HARPS) instrument on the 3.6 m Telescope. Its presence was confirmed by observations from several telescopes from the ESO. This discovery was announced in 2010 on St. Patrick's Day, after 145 days of continuous observations in summer 2008.
Mass and size
CoRoT-9b has a mass of 0.84 times that of Jupiter (MJ) as determined from HARPS spectroscopy, and has a radius of 1.05 times that of Jupiter (RJ) as determined from photometry of the transit light curve. This implies that this planet has a density of 96% that of water, and surface gravity 1.93 times that of Earth. A search for rings and satellites around this planet with the Spitzer space telescope was negative.
Atmosphere and interior
Since CoRoT-9b is the first temperate giant exoplanet found by the transit method, astronomers will be able to study the atmosphere of a temperate giant planet for the first time, examining the composition of clouds, the composition of the atmosphere, temperature distributions, and even some details of the interior of the planet. The atmosphere of this planet is presumably dominated by hydrogen and helium (like Jupiter and Saturn), with up to 20 Earth masses of other elements including water, as well as rock at high temperatures and pressures. The authors of the CoRoT-9b discovery paper refer to the planet as a class II ("water cloud") or class III ("clear") atmosphere planet, as described by the Sudarsky extrasolar planet classification.
See also
CoRoT is a CNES space mission to discover planets using the photometric transit method. It is in polar orbit around the Earth.
CoRoT-7b is a rocky super-Earth.
HD 80606 b is the longest period (but much more eccentric than CoRoT-9b) transiting planet.
GJ 1214 b is a transiting super-Earth found by MEarth Project.
References
External links
"CoRoT-9b, a temperate exoplanet" - DLR Portal, 2010.march.17
Exoplanets discovered in 2010
Transiting exoplanets
Giant planets
Serpens
9b
Articles containing video clips | CoRoT-9b | Astronomy | 658 |
224,034 | https://en.wikipedia.org/wiki/Tarpit%20%28networking%29 | A tarpit is a service on a computer system (usually a server) that purposely delays incoming connections. The technique was developed as a defense against a computer worm, and the idea is that network abuses such as spamming or broad scanning are less effective, and therefore less attractive, if they take too long. The concept is analogous with a tar pit, in which animals can get bogged down and slowly sink under the surface, like in a swamp.
The original tarpit idea
Tom Liston developed the original tarpitting program LaBrea. It can protect an entire network with a tarpit run on a single machine.
The machine listens for Address Resolution Protocol requests that go unanswered (indicating unused addresses), then replies to those requests, receives the initial SYN packet of the scanner and sends a SYN/ACK in response. It does not open a socket or prepare a connection, in fact it can forget all about the connection after sending the SYN/ACK. However, the remote site sends its ACK (which gets ignored) and believes the 3-way-handshake to be complete. Then it starts to send data, which never reaches a destination. The connection will time out after a while, but since the system believes it is dealing with a live (established) connection, it is conservative in timing it out and will instead try to retransmit, back-off, retransmit, etc. for quite a while.
Later versions of LaBrea also added functionality to reply to the incoming data, again using raw IP packets and no sockets or other resources of the tarpit server, with bogus packets that request that the sending site "slow down". This will keep the connection established and waste even more time of the scanner.
SMTP tarpits
One of the possible avenues that were considered to battle bulk-spam at one time, was to mandate a small fee for every submitted mail. By introducing such artificial cost, with negligible impact on legitimate use as long as the fee is small enough, automated mass-scale spam would instantly become unattractive. Tarpitting could be seen as a similar (but technically much less complex) approach, where the cost for the spammer would be measured in terms of time and efficiency rather than money.
Authentication procedures increase response times as users attempt invalid passwords. SMTP authentication is no exception. However, server-to-server SMTP transfers, which is where spam is injected, require no authentication. Various methods have been discussed and implemented for SMTP tarpits, systems that plug into the Mail Transfer Agent (MTA, i.e. the mail server software) or sit in front of it as a proxy.
One method increases transfer time for all mails by a few seconds by delaying the initial greeting message ("greet delay"). The idea is that it will not matter if a legitimate mail takes a little longer to deliver, but due to the high volume, it will make a difference for spammers. The downside of this is that mailing lists and other legitimate mass-mailings will have to be explicitly whitelisted or they will suffer, too.
Some email systems, such as sendmail 8.13+, implement a stronger form of greet delay. This form pauses when the connection is first established and listens for traffic. If it detects any traffic prior to its own greeting (in violation of RFC 2821) it closes the connection. Since many spammers do not write their SMTP implementations to the specification, this can reduce the number of incoming spam messages.
Another method is to delay only known spammers, e.g. by using a blacklist (see Spamming, DNSBL). OpenBSD has integrated this method into their core system since OpenBSD 3.3, with a special-purpose daemon (spamd) and functionality in the firewall (pf) to redirect known spammers to this tarpit.
MS Exchange can tarpit senders who send to an invalid address. Exchange can do this because the SMTP connector is connected to the authentication system.
A more subtle idea is greylisting, which, in simple terms, rejects the first connection attempt from any previously unseen IP address. The assumption is that most spammers make only one connection attempt (or a few attempts over a short period of time) to send each message, whereas legitimate mail delivery systems will keep retrying over a longer period. After they retry, they will eventually be allowed in without any further impediments.
Finally, a more elaborate method tries to glue tarpits and filtering software together, by filtering e-mail in realtime, while it is being transmitted, and adding delays to the communication in response to the filter's "spam likeliness" indicator. For example, the spam filter would make a "guess" after each line or after every x bytes received as to how likely this message is going to be spam. The more likely this is, the more the MTA will delay the transmission.
Background
SMTP consists of requests, which are mostly four-letter words such as MAIL, and replies, which are (minimally) three-digit numbers. In the last line of the reply, the number is followed by a space; in the preceding lines it is followed by a hyphen. Thus, on determining that a message being attempted to send is spam, a mail server can reply:
451-Ophiomyia prima is an agromyzid fly
451-Ophiomyia secunda is an agromyzid fly
451-Ophiomyia tertia is an agromyzid fly
451-Ophiomyia quarta is an agromyzid fly
451-Ophiomyia quinta is an agromyzid fly
451-Ophiomyia sexta is an agromyzid fly
451-Ophiomyia septima is an agromyzid fly
451 Your IP address is listed in the DNSBL. Please try again later.
The tarpit waits fifteen or more seconds between lines (long delays are allowed in SMTP, as humans sometimes send mail manually to test mail servers). This ties up the SMTP sending process on the spammer's computer so as to limit the amount of spam it can send.
IP-level tarpits
The Linux kernel can now be patched to allow tarpitting of incoming connections instead of the more usual dropping of packets. This is implemented in iptables by the addition of a TARPIT target. The same packet inspection and matching features can be applied to tarpit targets as are applied to other targets.
Mixed SMTP-IP level tarpits
A server can determine that a given mail message is spam, e.g. because it was addressed to a spam trap, or after trusted users' reports. The server may decide that the IP address responsible for submitting the message deserves tarpitting. Cross-checking against available DNSBLs can help to avoid including innocent forwarders in the tarpit database. A daemon exploiting Linux libipq can then check the remote address of incoming SMTP connections against that database. SpamCannibal is a GPL software designed around this idea; Stockade is a similar project implemented using FreeBSD ipfirewall.
One advantage of tarpitting at the IP level is that regular TCP connections handled by an MTA are stateful. That is, although the MTA doesn't use much CPU while it sleeps, it still uses the amount of memory required to hold the state of each connection. On the opposite, LaBrea-style tarpitting is stateless, thus gaining the advantage of a reduced cost against the spammer's box. However, it has to be noted that making use of botnets, spammers can externalize most of their computer-resource costs.
Criticism
It is known that a tarpitted connection may generate a significant amount of traffic towards the receiver, because the sender considers the connection as established and tries to send (and then retransmit) actual data. In practice, given current average computer botnet size, a more reasonable solution will be to drop suspicious traffic completely, without tarpitting. This way, only TCP SYN segments will be retransmitted, not the whole HTTP or HTTPS requests.
Commercial implementations of tar-pitting
As well as MS Exchange, there have been two other successful commercial implementations of the tar pit idea. The first was developed by TurnTide, a Philadelphia-based startup company, which was acquired by Symantec in 2004 for $28 million in cash. The TurnTide Anti Spam Router contains a modified Linux kernel which allows it to play various tricks with TCP traffic, such as varying the TCP window size. By grouping various email senders into different traffic classes and limiting the bandwidth for each class, the amount of abusive traffic is reduced - particularly when the abusive traffic is coming from single sources which are easily identified by their high traffic volume.
After the Symantec acquisition, a Canadian startup company called MailChannels released their "Traffic Control" software, which uses a slightly different approach to achieve similar results. Traffic Control is a semi-realtime SMTP proxy. Unlike the TurnTide appliance, which applies traffic shaping at the network layer, Traffic Control applies traffic shaping to individual senders at the application layer. This approach results in a somewhat more effective handling of spam traffic originating from botnets because it allows the software to slow traffic from individual spam zombies, rather than requiring zombie traffic to be aggregated into a class.
See also
Turing tarpit
Anti-spam techniques (e-mail)
Mail-sink
References
Computer network security
Anti-spam | Tarpit (networking) | Engineering | 2,023 |
28,987,287 | https://en.wikipedia.org/wiki/RNA%20recognition%20motif | RNA recognition motif, RNP-1 is a putative RNA-binding domain of about 90 amino acids that are known to bind single-stranded RNAs. It was found in many eukaryotic proteins.
The largest group of single strand RNA-binding protein is the eukaryotic RNA recognition motif (RRM) family that contains an eight amino acid RNP-1 consensus sequence.
RRM proteins have a variety of RNA binding preferences and functions, and include heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing (SR, U2AF2, Sxl), protein components of small nuclear ribonucleoproteins (U1 and U2 snRNPs), and proteins that regulate RNA stability and translation (PABP, La, Hu). The RRM in heterodimeric splicing factor U2 snRNP auxiliary factor appears to have two RRM-like domains with specialised features for protein recognition. The motif also appears in a few single stranded DNA binding proteins.
The typical RRM consists of four anti-parallel beta-strands and two alpha-helices arranged in a beta-alpha-beta-beta-alpha-beta fold with side chains that stack with RNA bases. A third helix is present during RNA binding in some cases. The RRM is reviewed in a number of publications.
Human proteins containing this domain
A2BP1; ACF; BOLL; BRUNOL4; BRUNOL5; BRUNOL6; CCBL2; CGI-96;
CIRBP; CNOT4; CPEB2; CPEB3; CPEB4; CPSF7; CSTF2; CSTF2T;
CUGBP1; CUGBP2; D10S102; DAZ1; DAZ2; DAZ3; DAZ4; DAZAP1;
DAZL; DNAJC17; DND1; EIF3S4; EIF3S9; EIF4B; EIF4H; ELAVL1;
ELAVL2; ELAVL3; ELAVL4; ENOX1; ENOX2; EWSR1; FUS; FUSIP1;
G3BP; G3BP1; G3BP2; GRSF1; HNRNPL; HNRPA0; HNRPA1; HNRPA2B1;
HNRPA3; HNRPAB; HNRPC; HNRPCL1; HNRPD; HNRPDL; HNRPF; HNRPH1;
HNRPH2; HNRPH3; HNRPL; HNRPLL; HNRPM; HNRPR; HRNBP1; HSU53209;
HTATSF1; IGF2BP1; IGF2BP2; IGF2BP3; LARP7; MKI67IP; MSI1; MSI2; MSSP-2;
MTHFSD; MYEF2; NCBP2; NCL; NOL8; NONO; P14;
PABPC1; PABPC1L; PABPC3; PABPC4; PABPC5; PABPN1; POLDIP3; PPARGC1;
PPARGC1A; PPARGC1B; PPIE; PPIL4; PPRC1; PSPC1; PTBP1; PTBP2;
PUF60; RALY; RALYL; RAVER1; RAVER2; RBM10; RBM11; RBM12;
RBM12B; RBM14; RBM15; RBM15B; RBM16; RBM17; RBM18; RBM19;
RBM22; RBM23; RBM24; RBM25; RBM26; RBM27; RBM28; RBM3;
RBM32B; RBM33; RBM34; RBM35A; RBM35B; RBM38; RBM39; RBM4;
RBM41; RBM42; RBM44; RBM45; RBM46; RBM47; RBM4B; RBM5;
RBM7; RBM8A; RBM9; RBMS1; RBMS2; RBMS3; RBMX; RBMX2;
RBMXL2; RBMY1A1; RBMY1B; RBMY1E; RBMY1F; RBMY2FP; RBPMS; RBPMS2;
RDBP; RNPC3; RNPC4; RNPS1; ROD1; SAFB; SAFB2; SART3;
SETD1A; SF3B6; SF3B4; SFPQ; SFRS1; SFRS10; SFRS11; SFRS12;
SFRS15; SRSF2; SFRS2B; SFRS3; SFRS4; SFRS5; SFRS6; SFRS7;
SFRS9; SLIRP; SLTM; SNRP70; SNRPA; SNRPB2; SPEN; SR140;
SRRP35; SSB; SYNCRIP; TAF15; TARDBP; THOC4; TIA1; TIAL1;
TNRC4; TNRC6C; TRA2A; TRSPAP1; TUT1; U1SNRNPBP; U2AF1; U2AF2;
UHMK1; ZCRB1; ZNF638; ZRSR1; ZRSR2;
References
External links
Protein domains
Protein superfamilies | RNA recognition motif | Biology | 1,221 |
1,972,565 | https://en.wikipedia.org/wiki/Cryptochrome | Cryptochromes (from the Greek κρυπτός χρώμα, "hidden colour") are a class of flavoproteins found in plants and animals that are sensitive to blue light. They are involved in the circadian rhythms and the sensing of magnetic fields in a number of species. The name cryptochrome was proposed as a portmanteau combining the chromatic nature of the photoreceptor, and the cryptogamic organisms on which many blue-light studies were carried out.
The genes CRY1 and CRY2 encode the proteins CRY1 and CRY2, respectively. Cryptochromes are classified into plant Cry and animal Cry. Animal Cry can be further categorized into insect type (Type I) and mammal-like (Type II). CRY1 is a circadian photoreceptor whereas CRY2 is a clock repressor which represses Clock/Cycle (Bmal1) complex in insects and vertebrates. In plants, blue-light photoreception can be used to cue developmental signals. Besides chlorophylls, cryptochromes are the only proteins known to form photoinduced radical-pairs in vivo. These appear to enable some animals to detect magnetic fields.
Cryptochromes have been the focus of several current efforts in optogenetics. Employing transfection, initial studies on yeast have capitalized on the potential of CRY2 heterodimerization to control cellular processes, including gene expression, by light.
Discovery
Although Charles Darwin first documented plant responses to blue light in the 1880s, it was not until the 1980s that research began to identify the pigment responsible. In 1980, researchers discovered that the HY4 gene of the plant Arabidopsis thaliana was necessary for the plant's blue light sensitivity, and, when the gene was sequenced in 1993, it showed high sequence homology with photolyase, a DNA repair protein activated by blue light. Reference sequence analysis of cryptochrome-1 isoform d shows two conserved domains with photolyase proteins. Isoform d nucleotide positions 6 through 491 show a conserved domain with deoxyribodipyrimidine photolyase, and positions 288 through 486 show a conserved domain with the FAD binding domain of DNA photolyase. Comparative genomic analysis supports photolyase proteins as the ancestors of cryptochromes. However, by 1995 it became clear that the products of the HY4 gene and its two human homologs did not exhibit photolyase activity and were instead a new class of blue light photoreceptor hypothesized to be circadian photopigments. In 1996 and 1998, Cry homologs were identified in Drosophila and mice, respectively.
Evolutionary history
Cryptochromes (CRY1, CRY2) are evolutionarily old and highly conserved proteins that belong to the flavoproteins superfamily that exists in all kingdoms of life. Cryptochromes are derived from and closely related to photolyases, which are bacterial enzymes that are activated by light and involved in the repair of UV-induced DNA damage.
In eukaryotes, cryptochromes no longer retain this original enzymatic activity. By using a T-DNA labeled allele of the cry1 gene in the Arabidopsis plant, researchers determined that the cry1 gene encoded a flavoprotein without photolyase activity and with a unique C-terminal tail. The protein encoded by this gene was named cryptochrome 1 to distinguish it from its ancestral photolyase proteins and was found to be involved in the photoreception of blue light. Studies of Drosophila cry-knockout mutants led to the later discovery that cryptochrome proteins are also involved in regulating the mammalian circadian clock. The Drosophila cry gene similarly encodes a flavoprotein without photolyase activity that also binds pterin chromophores. Cry mutants (cryb) were found to express arrhythmic levels of luciferase as well as PER and TIM proteins in photoreceptor cells. Despite the arrhythmicity of these protein levels, cryb mutants still showed rhythmicity in overall behavior but could not entrain to short pulses of light, leading researchers to conclude that the dorsal and ventral lateral neurons (the primary pacemaker cells of Drosophila) were still functioning effectively. When cryb mutants also had visually unresponsive compound eyes, though, they failed to behaviorally entrain to environmental cues. These findings led researchers to conclude that the cryptochrome protein encoded by cry is necessary for Drosophila photoentrainment. In mammals, a protein analog of the Drosophila cryptochrome protein was discovered with the characteristic property of lacking photolyase activity, prompting researchers to consider it in the same class of cryptochrome proteins. In mice, the greatest cry1 expression is observed in the suprachiasmatic nucleus (SCN) where levels rhythmically fluctuate. Due to the role of the SCN as the primary mammalian pacemaker as well as the rhythmic fluctuations in cry1 expression, researchers concluded cry1 was also necessary for the entrainment of mammalian circadian rhythms.
A common misconception in the evolutionary history of cryptochrome proteins is that mammalian and plant proteins are orthologs of each other that evolved directly from a shared photolyase gene. However, genomic analysis indicates that mammalian and fly cryptochrome proteins show greater sequence similarity to the (6-4) photolyase proteins than to plant cryptochrome proteins. It is therefore likely that plant and animal cryptochrome proteins show a unique case of convergent evolution by repeatedly evolving new functions independently of each other from a single common ancestral cry gene.
Research by Worthington et al. (2003) indicates that cryptochromes first evolved in bacteria and were identified in Vibrio cholerae. Genome sequencing of this bacteria identified three genes in the photolyase/cryptochrome family, all of which have the folate and flavin cofactors characteristic of these proteins. Of these genes, one encodes a photolyase, while the other two encode cryptochrome proteins designated VcCry1 and VcCry2. Cashmore AR et al. (1999) hypothesize that mammalian cryptochromes developed later in evolutionary history shortly after plants and animals diverged based on conserved genomic domains between animal cryptochromes and the Arabidopsis (6-4) photolyase protein. Based on the role of cryptochromes in the entrainment of mammalian circadian rhythms, current researchers hypothesize that they developed simultaneously with the coevolution of PER, TIM, CLOCK, and CYCLE proteins, but there is currently insufficient evidence to determine the exact evolution timing and mechanism of evolution.
Structure
All members of the flavoprotein superfamily have the characteristics of an N-terminal photolyase homology (PHR) domain. The PHR domain can bind to the flavin adenine dinucleotide (FAD) cofactor and a light-harvesting chromophore. The structure of cryptochrome involves a fold very similar to that of photolyase, arranged as an orthogonal bundle with a single molecule of FAD noncovalently bound to the protein. These proteins have variable lengths and surfaces on the C-terminal end, due to the changes in genome and appearance that result from the lack of DNA repair enzymes. The Ramachandran plot shows that the secondary structure of the CRY1 protein is primarily a right-handed alpha helix with little to no steric overlap. The structure of CRY1 is almost entirely made up of alpha helices, with several loops and few beta sheets.
Function
Phototropism
In plants, cryptochromes mediate phototropism, or directional growth toward a light source, in response to blue light. This response is now known to have its own set of photoreceptors, the phototropins.
Unlike phytochromes and phototropins, cryptochromes are not kinases. Their flavin chromophore is reduced by light and transported into the cell nucleus, where it affects the turgor pressure and causes subsequent stem elongation. To be specific, Cry2 is responsible for blue-light-mediated cotyledon and leaf expansion. Cry2 overexpression in transgenic plants increases blue-light-stimulated cotyledon expansion, which results in many broad leaves and no flowers rather than a few primary leaves with a flower. A double loss-of-function mutation in Arabidopsis thaliana Early Flowering 3 (elf3) and Cry2 genes delays flowering under continuous light and was shown to accelerate it during long and short days, which suggests that Arabidopsis CRY2 may play a role in accelerating flowering time during continuous light.
Photomorphogenesis
Cryptochromes receptors cause plants to respond to blue light via photomorphogenesis. They help control seed and seedling development, as well as the switch from the vegetative to the flowering stage of development.
In Arabidopsis, CRY1 is the primary inhibitor of hypocotyl elongation but CRY2 inhibits hypocotyl elongation under low blue light intensity. CRY2 promotes flowering under long-day conditions.
CRY gene mediates photomorphogenesis in several ways. CRY C-terminal interacts with CONTITUTIVE PHOTOMORPHOGENIC 1 (COP1), a E3 ubiquitin ligase that represses photomorphogenesis and flowering time. The interaction inhibits COP1 activity and allows transcription factors such as ELONGATED HYPOCOTYL 5 (HY5) to accumulate. HY5 is a basic leucine zipper (bZIP) factor that promotes photomorphogenesis by binding to light-responsive genes. CRY interacts with G protein β-subunit AGB1, where HY5 dissociates from AGB1 and becomes activated. CRY interacts with PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) and PIF5, repressors of photomorphogenesis and promoter of hypocotyl elongation, to repress PIF4 and PIF5 transcription activity. Lastly, CRY can inhibit auxin and brassinosterioid (BR) signaling to promote photomorphogenesis.
Light capture
Despite much research on the topic, cryptochrome photoreception and phototransduction in Drosophila and Arabidopsis thaliana is still poorly understood. Cryptochromes are known to possess two chromophores: pterin (in the form of 5,10-methenyltetrahydrofolic acid (MTHF)) and flavin (in the form of FAD). Both may absorb a photon, and in Arabidopsis, pterin appears to absorb at a wavelength of 380 nm and flavin at 450 nm. Past studies have supported a model by which energy captured by pterin is transferred to flavin. Under this model of phototransduction, FAD would then be reduced to FADH, which probably mediates the phosphorylation of a certain domain in cryptochrome. This could then trigger a signal transduction chain, possibly affecting gene regulation in the cell nucleus.
A new hypothesis proposes that partner molecules sense the transduction of a light signal into a chemical signal in plant cryptochromes, which could be triggered by a photo-induced negative charge on the FAD cofactor or on the neighboring aspartic acid within the protein. This negative charge would electrostatically repel the protein-bound ATP molecule and thereby also the protein C-terminal domain, which covers the ATP binding pocket prior to photon absorption. The resulting change in protein conformation could lead to phosphorylation of previously inaccessible phosphorylation sites on the C-terminus and the given phosphorylated segment could then liberate the transcription factor HY5 by competing for the same binding site at the negative regulator of photomorphogenesis COP1.
A different mechanism may function in Drosophila. The true ground state of the flavin cofactor in Drosophila CRY is still debated, with some models indicating that the FAD is in an oxidized form, while others support a model in which the flavin cofactor exists in anion radical form, •. Recently, researchers have observed that oxidized FAD is readily reduced to • by light. Furthermore, mutations that blocked photoreduction had no effect on light-induced degradation of CRY, while mutations that altered the stability of • destroyed CRY photoreceptor function. These observations provide support for a ground state of •. Researchers have also recently proposed a model in which is excited to its doublet or quartet state by absorption of a photon, which then leads to a conformational change in the CRY protein.
Also the ring eyes of the demosponge larva of Amphimedon queenslandica express a blue-light-sensitive cryptochrome (Aq-Cry2), which might mediate phototaxis. In contrast, the eyes of most animals use photo-sensitive opsins expressed in photoreceptor cells, which communicate information about light from the environment to the nervous system. However, A. queenslandica lacks a nervous system, like other sponges. And it does not have an opsin gene in its fully sequenced genome either, despite having many other G-protein-coupled receptors (GPCRs). Therefore, the sponge's unique eyes must have evolved a different mechanism to detect light and mediate phototaxis, possibly with cryptochromes or other proteins.
Iris function
Isolated irises constrict in response to light via a photomechanical transduction response (PMTR) in a variety of species and require either melanopsin or cryptochrome to do so. The iris of chicken embryos senses short-wavelength light via a cryptochrome, rather than opsins. Research by Margiotta and Howard (2020) shows that the PMTR of the chicken iris striated muscle occurs with CRY gene activation by 430 nm blue light. The PMTR was inhibited in CRY gene knockouts and decreased when flavin reductase was inhibited, but remained intact with the addition of melanopsin antagonists. Similarly, cytosolic CRY1 and CRY2 proteins were found in iris myotubes, and decreasing transcription of these genes inhibited PMTRs. The greatest iris PMTRs therefore correspond with the development of striated, rather than smooth, muscle fibers through CRY-mediated PMTRs.
Circadian rhythm
Studies in animals and plants suggest that cryptochromes play a pivotal role in the generation and maintenance of circadian rhythms. Similarly, cryptochromes play an important role in the entrainment of circadian rhythms in plants. In Drosophila, cryptochrome (dCRY) acts as a blue-light photoreceptor that directly modulates light input into the circadian clock, while in mammals, cryptochromes (CRY1 and CRY2) act as transcription repressors within the circadian clockwork. Some insects, including the monarch butterfly, have both a mammal-like and a Drosophila-like version of cryptochrome, providing evidence for an ancestral clock mechanism involving both light-sensing and transcriptional-repression roles for cryptochrome.
Cry mutants have altered circadian rhythms, showing that Cry affects the circadian pacemaker. Drosophila with mutated Cry exhibit little to no mRNA cycling. A point mutation in cryb, which is required for flavin association in CRY protein, results in no PER or TIM protein cycling in either DD or LD. In addition, mice lacking Cry1 or Cry2 genes exhibit differentially altered free running periods, but are still capable of photoentrainment. However, mice that lack both Cry1 and Cry2 are arrhythmic in both LD and DD and always have high Per1 mRNA levels. These results suggest that cryptochromes play a photoreceptive role, as well as acting as negative regulators of Per gene expression in mice.
In Drosophila
In Drosophila, cryptochrome is only encoded by one Cry gene (dCry) and functions as a blue light photoreceptor. Exposure to blue light induces a conformation similar to that of the always-active CRY mutant with a C-terminal deletion (CRYΔ). The half-life of this conformation is 15 minutes in the dark and facilitates the binding of CRY to other clock gene products, PER and TIM, in a light-dependent manner. Once bound by dCRY, dTIM is committed to degradation by the ubiquitin-proteasome system.
Although light pulses do not entrain, full photoperiod LD cycles can still drive cycling in the ventral-lateral neurons in the Drosophila brain. These data along with other results suggest that CRY is the cell-autonomous photoreceptor for body clocks in Drosophila and may play a role in nonparametric entrainment (entrainment by short discrete light pulses). However, the lateral neurons receive light information through both the blue light CRY pathway and the rhodopsin pathway. Therefore, CRY is involved in light perception and is an input to the circadian clock, however it is not the only input for light information, as a sustained rhythm has been shown in the absence of the CRY pathway, in which it is believed that the rhodopsin pathway is providing some light input. Recently, it has also been shown that there is a CRY-mediated light response that is independent of the classical circadian CRY-TIM interaction. This mechanism is believed to require a flavin redox-based mechanism that is dependent on potassium channel conductance. This CRY-mediated light response has been shown to increase action potential firing within seconds of a light response in opsin-knockout Drosophila.
Cryptochrome, like many genes involved in circadian rhythm, shows circadian cycling in mRNA and protein levels. In Drosophila, Cry mRNA concentrations cycle under a light-dark cycle (LD), with high levels in light and low levels in the dark. This cycling persists in constant darkness (DD), but with decreased amplitude. The transcription of the Cry gene also cycles with a similar trend. CRY protein levels, however, cycle in a different manner than Cry transcription and mRNA levels. In LD, CRY protein has low levels in light and high levels in dark, and, in DD, CRY levels increase continuously throughout the subjective day and night. Thus, CRY expression is regulated by the clock at the transcriptional level and by light at the translational and posttranslational level.
Overexpression of Cry also affects circadian light responses. In Drosophila, Cry overexpression increases flies' sensitivity to low-intensity light. This light regulation of CRY protein levels suggests that CRY has a circadian role upstream of other clock genes and components.
In mammals
In mammals, cryptochrome proteins are encoded by two genes, Cry1 and Cry2.
Cry2
Cryptochrome is one of the four groups of mammalian clock genes/proteins that generate a transcription-translation negative-feedback loop (TTFL), along with Period (PER), CLOCK, and BMAL1. In this loop, CLOCK and BMAL1 proteins are transcriptional activators, which together bind to the promoters of the Cry2 and Per genes and activate their transcription. The CRY2 and PER proteins then bind to each other, enter the nucleus, and inhibit CLOCK-BMAL1-activated transcription. The overall function of CRY2 is therefore to repress transcription of CLOCK and BMAL1.
Cry1
Cry1 encodes the CRY1 protein which is a mammalian circadian photoreceptor. In mice, Cry1 expression displays circadian rhythms in the suprachiasmatic nucleus, a brain region involved in the generation of circadian rhythms, with mRNA levels peaking during the light phase and reaching a minimum in the dark. These daily oscillations in expression are maintained in constant darkness.
While CRY1 has been well established as a TIM homolog in mammals, the role of CRY1 as a photoreceptor in mammals has been controversial. Early papers indicated that CRY1 has both light-independent and -dependent functions. A study conducted by Selby CP et al. (2000) found that mice without rhodopsin but with cryptochrome still respond to light; however, in mice without either rhodopsin or cryptochrome, c-Fos transcription, a mediator of light sensitivity, significantly drops. In recent years, data have supported melanopsin as the main circadian photoreceptor, in particular melanopsin cells that mediate entrainment and communication between the eye and the suprachiasmatic nucleus (SCN). One of the main difficulties in confirming or denying CRY as a mammalian photoreceptor is that when the gene is knocked out the animal goes arrhythmic, so it is hard to measure its capacity as purely a photoreceptor. However, some recent studies indicate that human CRY1 may mediate light response in peripheral tissues.
Normal mammalian circadian rhythm relies critically on delayed expression of Cry1 following activation of the Cry1 promoter. Whereas rhythms in Per2 promoter activation and Per2 mRNA levels have almost the same phase, Cry1 mRNA production is delayed by approximately four hours relative to Cry1 promoter activation. This delay is independent of CRY1 or CRY2 levels and is mediated by a combination of E/E'-box and D-box elements in the promoter and RevErbA/ROR binding elements (RREs) in the gene's first intron. Transfection of arrhythmic Cry1−/− Cry2−/− double-knockout cells with only the Cry1 promoter (causing constitutive Cry1 expression) is not sufficient to rescue rhythmicity. Transfection of these cells with both the promoter and the first intron is required for restoration of circadian rhythms in these cells.
There is evidence that CRY1 can play a role in how sleep-wake patterns can be inherited through families. There is a mutation, CRY1Δ11, that causes a delay in one's circadian rhythm. CRY1Δ11 is a splicing variant that has deleted an auto-inhibitory section of the gene. It causes a delay by increasing the affinity of CLOCK and BMAL which in turn lengthens the period. This causes people with this mutation to have a later sleep midpoint than the rest of the population, causing a disorder known as delayed sleep–wake phase disorder.
CRY1 is also a key modulator in DNA repair, specifically through temporal regulation. CRY1 has an impact in the cell cycle progression, particularly in the G2/M checkpoint, and the depletion of CRY1 leads to effects on DNA repair networks, including mismatch repair, UV, and nucleotide excision. In cancer, CRY1 is stabilized by DNA damage, which results in CRY1 expression being associated with worse outcomes in prostate cancer. Because of its role in DNA repair and being pro-tumorigenic, further research can use CRY1 as a therapeutic target.
Variants of CRY1 can have impacts on humans in regards to metabolic output. According to a 2021 study, metabolic outputs, measured by bowel movements, were severely different for participants who were wild type in comparison to those with the CRY1Δ11 variant. The participants with the variant had a delayed sleep cycle and delayed metabolic output when compared to the wild type.
Magnetoreception
Magnetoreception is a sense which allows an organism to detect a magnetic field to perceive direction, altitude or location. Experimental data suggests that cryptochromes in the photoreceptor neurons of birds' eyes are involved in magnetic orientation during migration. Cryptochromes are also thought to be essential for the light-dependent ability of Drosophila to sense magnetic fields. Magnetic fields were once reported to affect cryptochromes also in Arabidopsis thaliana plants: growth behavior seemed to be affected by magnetic fields in the presence of blue (but not red) light. Nevertheless, these results have later turned out to be irreproducible under strictly controlled conditions in another laboratory, suggesting that plant cryptochromes do not respond to magnetic fields.
Cryptochrome forms a pair of radicals with correlated spins when exposed to blue light. Radical pairs can also be generated by the light-independent dark reoxidation of the flavin cofactor by molecular oxygen through the formation of a spin-correlated FADH-superoxide radical pairs. Magnetoreception is hypothesized to function through the surrounding magnetic field's effect on the correlation (parallel or anti-parallel) of these radicals, which affects the lifetime of the activated form of cryptochrome. Activation of cryptochrome may affect the light-sensitivity of retinal neurons, with the overall result that the animal can sense the magnetic field. Animal cryptochromes and closely related animal (6-4) photolyases contain a longer chain of electron-transferring tryptophans than other proteins of the cryptochrome-photolyase superfamily (a tryptophan tetrad instead of a triad). The longer chain leads to a better separation and over 1000× longer lifetimes of the photoinduced flavin-tryptophan radical pairs than in proteins with a triad of tryptophans. The absence of spin-selective recombination of these radical pairs on the nanosecond to microsecond timescales seems to be incompatible with the suggestion that magnetoreception by cryptochromes is based on the forward light reaction.
References
External links
Cryptochrome circadian clock in Monarch Butterflies , by Steven M. Reppert, Department of Neurobiology, University of Massachusetts
Cryptochrome and Magnetic Sensing, Theoretical and Computational Biophysics Group at the University of Illinois at Urbana-Champaign
2IJG at the Protein Data Bank; 3-D structure of Arabidopsis cryptochrome 3, obtained by X-ray crystallography.
Animated model of murine circadian pathway, including role of Cry
Physiology
Biological pigments
Sensory receptors
Plant intelligence | Cryptochrome | Biology | 5,544 |
384,948 | https://en.wikipedia.org/wiki/Methyl%20violet | Methyl violet is a family of organic compounds that are mainly used as dyes. Depending on the number of attached methyl groups, the color of the dye can be altered. Its main use is as a purple dye for textiles and to give deep violet colors in paint and ink. It is also used as a hydration indicator for silica gel. Methyl violet 10B is also known as crystal violet (and many other names) and has medical uses.
Structure
The term methyl violet encompasses three compounds that differ in the number of methyl groups attached to the amine functional group. Methyl violets are mixtures of tetramethyl (2B), pentamethyl (6B) and hexamethyl (10B) pararosanilins.
They are all soluble in water, ethanol, diethylene glycol and dipropylene glycol.
{|class="wikitable" style="text-align:center"
|-
!Name
| Methyl violet 2B || Methyl violet 6B || Methyl violet 10B (Crystal violet)
|-
!Structure
| || ||
|-
!Formula (salt)
| C23H26ClN3 || C24H28ClN3 || C25H30ClN3
|-
!CAS no
| 84215-49-6 || 8004-87-3 || 548-62-9
|-
!C.I.
| 42536 || 42535 || 42555
|-
!ChemSpider ID
| 21164086 || 170606 || 10588
|-
!PubChem ID
| 91997555 || 164877 || 11057
|-
!Formula (cation)
| C23H26N3+ || C24H28N3+ || C25H30N3+
|-
!ChemSpider ID
| || 2006225 || 3349, 9080056, 10354393
|-
!PubChem ID
| || 2724053 || 3468
|}
Methyl violet 2B
Methyl violet 2B (IUPAC name: 4,4′-((4-Iminocyclohexa-2,5-dien-1-ylidene)methylene)bis(N,N-dimethylaniline) monohydrochloride) is a green powder which is soluble in water and ethanol but not in xylene. It appears yellow in solution of low pH (approximately 0.15) and changes to violet with pH increasing toward 3.2.
Methyl violet 10B
Methyl violet 10B has six methyl groups. It is known in medicine as Gentian violet (or crystal violet or pyoctanin(e)) and is the active ingredient in a Gram stain, used to classify bacteria. It is used as a pH indicator, with a range between 0 and 1.6. The protonated form (found in acidic conditions) is yellow, turning blue-violet above pH levels of 1.6.
Methyl violet 10B inhibits the growth of many Gram positive bacteria, except streptococci. When used in conjunction with nalidixic acid (which destroys gram-negative bacteria), it can be used to isolate the streptococci bacteria for the diagnosis of an infection.
Degradation
Methyl violet is a mutagen and mitotic poison, therefore concerns exist regarding the ecological impact of the release of methyl violet into the environment. Methyl violet has been used in vast quantities for textile and paper dyeing, and 15% of such dyes produced worldwide are released to environment in wastewater. Numerous methods have been developed to treat methyl violet pollution. The three most prominent are chemical bleaching, biodegradation, and photodegradation.
Chemical bleaching
Chemical bleaching is achieved by oxidation or reduction. Oxidation can destroy the dye completely, e.g. through the use of sodium hypochlorite (NaClO, common bleach) or hydrogen peroxide. Reduction of methyl violet occurs in microorganisms but can be attained chemically using sodium dithionite.
Biodegradation
Biodegradation has been well investigated because of its relevance to sewage plants with specialized microorganisms. Two microorganisms that have been studied in depth are the white rot fungus and the bacterium Nocardia corallina.
Photodegradation
Light alone does not rapidly degrade methyl violet, but the process is accelerated upon the addition of large band-gap semiconductors, titanium dioxide or zinc oxide.
Other methods
Many other methods have been developed to treat the contamination of dyes in a solution, including electrochemical degradation, ion exchange, laser degradation, and absorption onto various solids such as activated charcoal.
See also
Fuchsine
Methylene blue
Methyl blue
Egyptian Blue
Han Purple
Fluorescein
References
Triarylmethane dyes
Disinfectants
PH indicators
Staining dyes
Anilines
Chlorides
Dimethylamino compounds | Methyl violet | Chemistry,Materials_science | 1,039 |
27,559,881 | https://en.wikipedia.org/wiki/Got%20%28bull%29 | Got is a fighting bull (born 18 May 2010 in Spain) who was cloned from another fighting bull named Vasito by teams at the Prince Felipe Research Center and the Valencia Foundation for Veterinary Research using nuclear transfer. This is thought to be the first time a fighting bull has been successfully cloned.
Vicente Torrent from the Valencia Foundation for Veterinary Research, who led the project, said that Got was the culmination of three years of research into how to preserve "valuable bull genes" costing €28,000.
References
Cloned animals
2010 animal births
Individual bulls in sport
Individual animals in Spain | Got (bull) | Biology | 122 |
60,462,641 | https://en.wikipedia.org/wiki/Carrelame | Carrelame is an extremely high potency artificial sweetener of the guanidine class, closely related to lugduname. While Carrelame is roughly 200,000 times as sweet as sucrose, lugduname is still somewhat sweeter. It appears safe in pigs.
See also
Sucrononic acid
Additional reading
References
Acetic acids
Sugar substitutes
Guanidines | Carrelame | Chemistry | 81 |
57,370,057 | https://en.wikipedia.org/wiki/Belgium%20Pier | The Belgium Pier is a pier in Blankenberge, Belgium. It was built in 1933 after an Art Deco design by architect Jules Soete. The concrete structure stretches 350 meters out into the North Sea. The Belgium Pier replaced an earlier structure that was the first pier at the Atlantic and North Sea coasts of the European continent, and the only other pier like it is the Scheveningen Pier in the Netherlands.
External links
Coastal construction
Marine architecture
Piers in Belgium
1933 establishments in Belgium
Buildings and structures completed in 1933
Art Deco architecture in Belgium | Belgium Pier | Engineering | 109 |
8,091,361 | https://en.wikipedia.org/wiki/Policeman%20%28laboratory%29 | A policeman is a hand-held flexible natural-rubber or plastic scraper. The common type of it is attached to a glass rod and used in chemical laboratories to transfer residues of precipitate or solid on glass surfaces when performing gravimetric analysis. This equipment works well under gentle, delicate and precise requirement. A policeman also comes in various sizes, shapes, and types. Some of them come in one-piece flexible plastic version and some in stainless. The origin of the policeman and its name cannot be identified for sure but some clues led back to the 19th century from German chemist Carl Remigius Fresenius.
Structure
A policeman is generally a flexible natural-rubber blade attached to a glass rod, which is typically 5 mm to 6 mm diameter and 150 mm long. However, it also comes in various sizes and shapes depending on its uses. The rubber material provides chemical resistance. In some designs, there is no glass rod, but instead the whole item is made of plastic or stainless steel and is shaped into a spatula or scraper shape at the end.
Uses
A policeman can be used for cleaning the inside of glassware, or for getting the last bit of precipitate out of a vessel. Especially in chemical laboratories it is often used to transfer residues of precipitate or solid on glass surfaces when performing the gravimetric analysis. It also used in biological laboratories, to transfer tissue culture cells from a plate to a suspension. It feature is to prevent the glass rod from scratching or breaking glassware.
Origin
There is no answer on where the name "policeman" comes from, though it may be related to the function of the instrument.
It is like the police in that it protects the beaker from scratching.
It is like the police in that it gathers up any stray or escaped particles of precipitate on the beaker wall.
In chemistry, gravimetric analysis is essential. After precipitating the chemical element of interest, successfully transferring all of the precipitate to the filtration funnel for separation from the supernatant liquid is required. This can be done by using a stream of distilled water from a wash bottle. This is less effective because dense precipitates may become compacted at the bottom of the beaker, while light precipitates may be dispersed on the walls of the beaker. A glass rod can be used to remove the precipitate but this risks poking a hole in the bottom of the beaker or scratching the beaker wall. In the 19th century, German chemist, Carl Remigius Fresenius suggested a solution to overcome this problem using a device similar to the rubber policeman.
Then rubber policeman was also recorded in 1910 edition of J. C. Olsen's textbook of quantitative analysis that states "particles adhering to the glass must be removed by means of a so-called policeman, which is made by inserting the end of a rather thick large-sized glass stirring-rod into a short piece of rubber tubing. The rubber tube should be left protruding slightly beyond the end of the glass tube and sealed together with a little bicycle [i.e. rubber] cement."
However, it seems that Olsen has nothing to do with the mass production and sales of this invention. Instead, Oesper Collections catalog indicated that Henry Heil Company of St. Louis sold policemen as early as 1904.
The second speculation is the most likely the one since in the 1937 edition of Hackh's Chemical Dictionary "platinum policeman," defined as "a platinum-iridium claw that fits over a glass rod and is used to hold a quantitative filter during ignition," which the purpose of the policeman was to prevent the escape of stray filter paper from the crucible during the ignition process that causes thermal updrafts from the burner. Therefore, for policeman, it likely means to prevent the escape of stray precipitate.
See also
Glass rod
Spatula
Beaker
References
Laboratory equipment
Microbiology equipment
Chemical equipment | Policeman (laboratory) | Chemistry,Engineering,Biology | 818 |
9,780,169 | https://en.wikipedia.org/wiki/UNESCO%20statements%20on%20race | UNESCO has published several statements about issues of race.
The statements include:
Statement on race (Paris, July 1950)
Statement on the nature of race and race differences (Paris, June 1951)
Proposals on the biological aspects of race (Moscow, August 1964)
Statement on race and racial prejudice (Paris, September 1967)
Other statements include the Declaration on the Elimination of All Forms of Racial Discrimination (1963), the "Declaration on Race and Racial Prejudice" (1978) and the "Declaration of Principles on Tolerance" (1995).
Statement on race (1950)
Statement on race is the first statement on race issued by UNESCO. It was issued on 18 July 1950 following World War II and Nazi racism, to clarify what was scientifically known about race, and as a moral condemnation of racism.
It was drafted by Ernest Beaglehole, psychologist and ethnologist; Juan Comas, anthropologist; Luiz de Aguiar Costa Pinto, sociologist; Franklin Frazier, sociologist specialised in race relations studies; Morris Ginsberg, founding chairperson of the British Sociological Association; Humayun Kabir, writer, philosopher, and twice Education Minister of India; Claude Lévi-Strauss, one of the founders of ethnology and leading theorist of structural anthropology; and Ashley Montagu, anthropologist and author of The Elephant Man: A Study in Human Dignity, who was the rapporteur.
The text was then revised by Ashley Montagu following criticisms submitted by Hadley Cantril; Edwin Conklin; Gunnar Dahlberg; Theodosius Dobzhansky, author of Genetics and the Origin of Species (1937); L. C. Dunn; Donald J. Hager, professor of anthropology and sociology at the University of Princeton; Julian Huxley, first director of UNESCO and one of the many key contributors to modern evolutionary synthesis; Otto Klineberg; Wilbert Moore; H. J. Muller; Gunnar Myrdal, author of An American Dilemma: The Negro Problem and Modern Democracy (1944); Joseph Needham, a biochemist specialist of Chinese science; and geneticist Curt Stern.
The statement was criticized on several grounds and a revised statement was published in 1951, as well as a book detailing the criticisms in 1952. Further statements were published in 1964, 1967, and 1978.
UNESCO would start a campaign to spread the results of the report to a "vast public" such as by publishing pamphlets. It described Brazil as having an "exemplary situation" regarding race relations and that research should be undertaken in order to understand the causes of this "harmony".
Contents
The introduction states that it was inevitable that UNESCO should take a position in the controversy. The preamble to the UNESCO constitution states that it should combat racism. The constitution itself stated that "The great and terrible war that has now ended was a war made possible by the denial of the democratic principles of the dignity, equality and mutual respect of men, and by the propagation, in their place, through ignorance and prejudice, of the doctrine of the inequality of men and races."
A 1948 UN Social and Economic Council resolution called upon UNESCO to consider the timeliness "of proposing and recommending the general adoption of a programme of dissemination of scientific facts designed to bring about the disappearance of that which is commonly called race prejudice." In 1949, the General Conference of UNESCO adopted three resolutions which committed it to "study and collect scientific materials concerning questions of race", "to give wide diffusion to the scientific material collected", and "to prepare an education campaign based on this information."
Furthermore, in doing this
The introduction stated "Knowledge of the truth does not always help change emotional attitudes that draw their real strength from the subconscious or from factors beside the real issue." But it could "however, prevent rationalizations of reprehensive acts or behaviour prompted by feelings that men will not easily avow openly."
UNESCO made a moral statement:
The statement argued that there was no evidence for intellectual or personality differences.
The statement did not reject the idea of a biological basis to racial categories. It defined the concept of race in terms of a population defined by certain anatomical and physiological characteristics diverging from other populations; it gives as examples the Caucasian, Mongoloid, and Negroid races. However, the statement argued that "National, religious, geographic, linguistic and cultural groups do not necessarily coincide with racial groups: and the cultural traits of such groups have no demonstrated genetic connection with racial traits. Because serious errors of this kind are habitually committed when the term 'race' is used in popular parlance, it would be better when speaking of human races to drop the term 'race' altogether and speak of ethnic groups."
Statement on the nature of race and race differences (1951)
Despite the introduction to the 1950 statement declaring "The competence and objectivity of the scientists who signed the document in its final form cannot be questioned", the first version of the statement was heavily criticized.
L.C. Dunn, the rapporteur for the 1951 statement, explained the controversy as "At the first discussion on the problem of race, it was chiefly sociologists who gave their opinions and framed the 'Statement on Race'. That statement had a good effect, but it did not carry the authority of just those groups within whose special province fall the biological problems of race, namely the physical anthropologists and geneticists. Secondly, the first statement did not, in all its details, carry conviction of these groups and, because of this, it was not supported by many authorities in these two fields. In general, the chief conclusions of the first statement were sustained, but with differences in emphasis and with some important omissions."
The 1951 statement declared that Homo sapiens is one species.
The authors of the 1951 statement "agreed to reserve race as the word to be used" for "groups of mankind possessing well-developed and primarily heritable physical differences from other groups."
"The concept of race is unanimously regarded by anthropologists as a classificatory device providing a zoological frame within which the various groups of mankind may be arranged and by means of which studies of evolutionary processes can be facilitated. In its anthropological sense, the word 'race' should be reserved for groups of mankind possessing well-developed and primarily heritable physical differences from other groups." These differences have been caused in part by partial isolation preventing intermingling, geography an important explanation for the major races, often cultural for the minor races. National, religious, geographical, linguistic and cultural groups do not necessarily coincide with racial groups.
The statement declared "There is no evidence for the existence of so-called 'pure races'" and "no biological justification for prohibiting inter- marriage between persons of different races."
The Race Concept (1952)
In 1952, UNESCO published a follow-up book, The Race Concept: Results of an Inquiry, containing the 1951 statement, followed by comments and criticisms from many of the scientists engaged in the drafting and review of the text.
Four scientists are listed as "frankly opposed" to the statement as a whole: C. D. Darlington, Ronald Fisher, Giuseppe E. Genna of the University of Florence, and Carleton S. Coon. Among these, English statistician and biologist Fisher insisted on racial differences, arguing that evidence and everyday experience showed that human groups differ profoundly "in their innate capacity for intellectual and emotional development" and concluded that the "practical international problem is that of learning to share the resources of this planet amicably with persons of materially different nature", and that "this problem is being obscured by entirely well-intentioned efforts to minimize the real differences that exist."
The book stated that "When intelligence tests, even non-verbal, are made on a group of non-literate people, their scores are usually lower than those of more civilised people" but concluded that "Available scientific knowledge provides no basis for believing that the groups of mankind differ in their innate capacity for intellectual and emotional development."
Statement on race and racial prejudice (1967)
According to Michael Banton, "The 1950 statement appeared to assume that once the erroneous nature of racist doctrines had been exposed, the structure of racial prejudice and discrimination would collapse. The eminent scholars who composed the document did not consider explicitly the other sources of racial hostility." Therefore, in 1967 a fourth panel of experts was assembled for one week to discuss social, ethical and philosophical aspects of race.
Declaration on Race and Racial Prejudice (1978)
In 1978, the Declaration on Race and Racial Prejudice was adopted by the General Conference of UNESCO, a political body consisting of representatives of member states. This declaration stated that "All peoples of the world possess equal faculties for attaining the highest level in intellectual, technical, social, economic, cultural and political development" and "The differences between the achievements of the different peoples are entirely attributable to geographical, historical, political, economic, social and cultural factors." It also argued for implementing a number of policies in order to combat racism and inequalities, and stated that "Population groups of foreign origin, particularly migrant workers and their families who contribute to the development of the host country, should benefit from appropriate measures designed to afford them security and respect for their dignity and cultural values and to facilitate their adaptation to the host environment and their professional advancement with a view to their subsequent reintegration in their country of origin and their contribution to its development; steps should be taken to make it possible for their children to be taught their mother tongue."
A draft of the statement was prepared by the Director-General and "eminent specialists in human rights". It was discussed at a meeting by government representatives from over 100 member states. It was recommended that the representatives should include among them "social scientists and other persons particularly qualified to in the social, political, economic, cultural, and scientific aspects of the problem". A number of non-governmental and inter-governmental organizations sent observers. A final text of was adopted by the meeting of government representatives "by consensus, without opposition or vote" and later by the UNESCO General Conference, Twentieth Session.
Declaration of Principles on Tolerance (1995)
In 1995, UNESCO published a Declaration of Principles on Tolerance to add to its dialogue about racial equality with recommendations for tolerant treatment of persons with varied racial and cultural backgrounds. It stated "Tolerance is respect, acceptance and appreciation of the rich diversity of our world's cultures, our forms of expression and ways of being human. It is fostered by knowledge, openness, communication, and freedom of thought, conscience and belief. Tolerance is harmony in difference. It is not only a moral duty, it is also a political and legal requirement. Tolerance, the virtue that makes peace possible, contributes to the replacement of the culture of war by a culture of peace."
Legacy
The 1950 UNESCO statement contributed to the 1954 U.S. Supreme Court desegregation decision in Brown v. Board of Education of Topeka.
See also
Convention on the Protection and Promotion of the Diversity of Cultural Expressions
International Convention on the Elimination of All Forms of Racial Discrimination
International Day for Tolerance
Nazism and race
Racial Equality Proposal
World Conference against Racism
References
External links
The Race Question, 1950
Statement on Race and Racial Prejudice, 1967
Scientific racism
UNESCO
1950 in science
Ethnicity
Ethnology
Historical definitions of race
Race (human categorization)
Politics and race
1950 in politics
1950 documents
1951 documents
1952 documents
1963 documents
1964 documents
1967 documents
1978 documents | UNESCO statements on race | Biology | 2,308 |
10,270,766 | https://en.wikipedia.org/wiki/Autophagin | Autophagin-1 (Atg4/Apg4) is a unique cysteine protease responsible for the cleavage of the carboxyl terminus of Atg8/Apg8/Aut7, a reaction essential for its lipidation during autophagy. Human Atg4 homologues cleave the carboxyl termini of the three human Atg8 homologues, microtubule-associated protein light chain 3 (LC3), GABARAP, and GATE-16.
The rapid advancement in our understanding of the mechanisms and regulation of autophagy has placed this process in the center of current research in major human disorders. The future challenge is to develop easy methods to separately manipulate the activity of each of the autophagic pathways. This would allow researchers to further understand their contribution to disease such as cancer, neurodegeneration, infectious disease, muscular disorders and possibly will provide therapeutic tools.
See also
Autophagy
Apoptosis
Ubiquitin
References
EC 3.4.22
Post-translational modification
Cellular processes | Autophagin | Chemistry,Biology | 222 |
1,411,188 | https://en.wikipedia.org/wiki/Activated%20sludge | The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa. It is one of several biological wastewater treatment alternatives in secondary treatment, which deals with the removal of biodegradable organic matter and suspended solids. It uses air (or oxygen) and microorganisms to biologically oxidize organic pollutants, producing a waste sludge (or floc) containing the oxidized material.
The activated sludge process for removing carbonaceous pollution begins with an aeration tank where air (or oxygen) is injected into the waste water. This is followed by a settling tank to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water. Part of the waste sludge is recycled to the aeration tank and the remaining waste sludge is removed for further treatment and ultimate disposal.
Plant types include package plants, oxidation ditch, deep shaft/vertical treatment, surface-aerated basins, and sequencing batch reactors (SBRs). Aeration methods include diffused aeration, surface aerators (cones) or, rarely, pure oxygen aeration.
Sludge bulking can occur which makes activated sludge difficult to settle and frequently has an adverse impact on final effluent quality. Treating sludge bulking and managing the plant to avoid a recurrence requires skilled management and may require full-time staffing of a works to allow immediate intervention. A new development of the activated sludge process is the Nereda process which produces a granular sludge that settles very well.
Purpose
The activated sludge process is a biological process used to oxidise carbonaceous biological matter, oxidising nitrogenous matter (mainly ammonium and nitrogen) in biological matter, and removing nutrients (nitrogen and phosphorus).
Process description
The process takes advantage of aerobic micro-organisms that can digest organic matter in sewage, and clump together by flocculation entrapping fine particulate matter as they do so. It thereby produces a liquid that is relatively free from suspended solids and organic material, and flocculated particles that will readily settle out and can be removed.
The general arrangement of an activated sludge process for removing carbonaceous pollution includes the following items:
Aeration tank where air (or oxygen) is injected in the mixed liquor.
Settling tank (usually referred to as "final clarifier" or "secondary settling tank") to allow the biological flocs (the sludge blanket) to settle, thus separating the biological sludge from the clear treated water.
Treatment of nitrogenous or phosphorous matter comprises the addition of an anoxic compartment inside the aeration tank in order to perform the nitrification-denitrification process more efficiently. First, ammonia is oxidized to nitrite, which is then converted into nitrate in aerobic conditions (aeration compartment). Facultative bacteria then reduce the nitrate to nitrogen gas in anoxic conditions (anoxic compartment). Moreover, the organisms used for the phosphorus uptake (Polyphosphate Accumulating Organisms) are more efficient under anoxic conditions. These microorganisms accumulate large amounts of phosphates in their cells and are settled in the secondary clarifier. The settled sludge is either disposed of as waste activated sludge or reused in the aeration tank as return activated sludge. Some sludge must always be returned to the aeration tanks to maintain an adequate population of organisms.
The yield of PAOs (Polyphosphate Accumulating Organisms) is reduced between 70 and 80% under aerobic conditions. Even though the phosphorus can be removed upstream of the aeration tank by chemical precipitation (adding metal ions such as: calcium, aluminum or iron), the biological phosphorus removal is more economic due to the saving of chemicals.
Bioreactor and final clarifier
The process involves air or oxygen being introduced into a mixture of screened, and primary treated sewage or industrial wastewater (wastewater) combined with organisms to develop a biological floc which reduces the organic content of the sewage. This material, which in healthy sludge is a brown floc, is largely composed of Saprotrophic bacteria but also has an important protozoan flora component mainly composed of amoebae, Spirotrichs, Peritrichs including Vorticellids and a range of other filter-feeding species. Other important constituents include motile and sedentary Rotifers. In poorly managed activated sludge, a range of mucilaginous filamentous bacteria can develop - including Sphaerotilus natans, Gordonia, and other microorganisms - which produces a sludge that is difficult to settle and can result in the sludge blanket decanting over the weirs in the settlement tank to severely contaminate the final effluent quality. This material is often described as sewage fungus but true fungal communities are relatively uncommon.
The combination of wastewater and biological mass is commonly known as mixed liquor. In all activated sludge plants, once the wastewater has received sufficient treatment, excess mixed liquor is discharged into settling tanks and the treated supernatant is run off to undergo further treatment before discharge. Part of the settled material, the sludge, is returned to the head of the aeration system to re-seed the new wastewater entering the tank. This fraction of the floc is called return activated sludge (R.A.S.).
The space required for a sewage treatment plant can be reduced by using a membrane bioreactor to remove some wastewater from the mixed liquor prior to treatment. This results in a more concentrated waste product that can then be treated using the activated sludge process.
Many sewage treatment plants use axial flow pumps to transfer nitrified mixed liquor from the aeration zone to the anoxic zone for denitrification. These pumps are often referred to as internal mixed liquor recycle pumps (IMLR pumps). The raw sewage, the RAS, and the nitrified mixed liquor are mixed by submersible mixers in the anoxic zones in order to achieve denitrification.
Sludge production
Activated sludge is also the name given to the active biological material produced by activated sludge plants. Excess sludge is called "surplus activated sludge" or "waste activated sludge" and is removed from the treatment process to keep "food to biomass" (F/M) ratio in balance (where biomass refers to the activated sludge). This sewage sludge is usually mixed with primary sludge from the primary clarifiers and undergoes further sludge treatment for example by anaerobic digestion, followed by thickening, dewatering, composting and land application.
The amount of sewage sludge produced from the activated sludge process is directly proportional to the amount of wastewater treated. The total sludge production consists of the sum of primary sludge from the primary sedimentation tanks as well as waste activated sludge from the bioreactors. The activated sludge process produces about of waste activated sludge (that is grams of dry solids produced per cubic metre of wastewater treated). is regarded as being typical. In addition, about of primary sludge is produced in the primary sedimentation tanks which most - but not all - of the activated sludge process configurations use.
Process control
The general process control method is to monitor sludge blanket level, SVI (Sludge Volume Index), MCRT (Mean Cell Residence Time), F/M (Food to Microorganism), as well as the biota of the activated sludge and the major nutrients DO (Dissolved oxygen), nitrogen, phosphate, BOD (Biochemical oxygen demand), and COD (Chemical oxygen demand). In the reactor/aerator and clarifier system, the sludge blanket is measured from the bottom of the clarifier to the level of settled solids in the clarifier's water column; this, in large plants, can be done up to three times a day.
The SVI is the volume of settled sludge occupied by a given mass of dry sludge solids. It is calculated by dividing the volume of settled sludge in a mixed liquor sample, measured in milliliters per liter of sample (after 30 minutes of settling), by the MLSS (Mixed Liquor Suspended Solids), measured in grams per liter. The MCRT is the total mass (in kilograms or pounds) of mixed liquor suspended solids in the aerator and clarifier divided by the mass flow rate (in kilograms/pounds per day) of mixed liquor suspended solids leaving as WAS and final effluent. The F/M is the ratio of food fed to the microorganisms each day to the mass of microorganisms held under aeration. Specifically, it is the amount of BOD fed to the aerator (in kilograms/pounds per day) divided by the amount (in kilograms or pounds) of Mixed Liquor Volatile Suspended Solids (MLVSS) under aeration. Note: Some references use MLSS (Mixed Liquor Suspended Solids) for expedience, but MLVSS is considered more accurate for the measure of microorganisms. Again, due to expedience, COD is generally used, in lieu of BOD, as BOD takes five days for results.
To ensure good bacterial settlement and to avoid sedimentation problems caused by filamentous bacteria, plants using atmospheric air as an oxygen source should maintain a dissolved oxygen (DO) level of about 2 mg/L in the aeration tank. In pure oxygen systems, DO levels are usually in the range of 4 to 10 mg/L. Operators should monitor the tank for low DO bacteria, such as S. natans, type 1701 and H. hydrossis, which indicate low DO conditions by elevated effluent turbidity and dark activated sludge with foul odours. Many plants have on-line monitoring equipment that continuously measures and records DO levels at specific points within the aeration tank. These on-line analysers send data to the SCADA system and allow automatic control of the aeration system to maintain a predetermined DO level. Whether generated automatically or taken manually, regular monitoring is necessary to favour organisms that settle well rather than filaments. However, operating the aeration system involves finding a balance between sufficient oxygen for proper treatment and the energy cost, which represents approximately 90% of the total treatment cost.
Based on these control methods, the amount of settled solids in the mixed liquor can be varied by wasting activated sludge (WAS) or returning activated sludge (RAS).
The returning activated sludge is designed to recycle a portion of the activated sludge from the secondary clarifier back to the aeration tank. It usually includes a pump that draws the portion back.
The RAS line is designed considering the potential for clogging, settling, and other relatable issues that manage to impact the flow of the activated sludge back to the aeration tank. This line must handle the required flow of the plant and has to be designed to minimize the risk of solids settling or accumulating.
Nitrification and Denitrification
Ammonium can have a toxic effect on aquatic organism. Nitrification also takes place in bodies of water, which leads to oxygen depletion. Furthermore, nitrate and ammonium are eutrophying (fertilizing) nutrients that can impair water bodies. For these reasons, nitrification and, in many cases, nitrogen removal is necessary.
Two special steps are required for nitrogen removal:
a) Nitrification: Oxidation of ammonium nitrogen and organically bound nitrogen to nitrate. Nitrification is very sensitive to inhibitors and can lead to a pH value in poorly buffered water.
Nitrification takes places in following steps:
this results in:
Nitrification is associated with the production of acid (H+). This puts a strain on the buffering capacity of the water or a pH value shift may occur, which impairs the process.
b) Denitrification: Reduction of nitrate nitrogen to molecular nitrogen, which escapes from the wastewater into the atmosphere. This step can be carried out by microorganisms commonly found in sewage treatment plants. However, these only use the nitrate as an electron acceptor if no dissolved oxygen is present.
In order for denitrification to take place in the activated sludge process, an electron source, a reductant, must therefore also be present that can reduce sufficient nitrate to N2. If there is too little substrate in the raw wastewater, this can be added artificially. In addition, denitrification corrects the change in H+ concentration (pH value shift) that occurs during nitrification. This is particularly important for poorly buffered water.
Nitrification and denitrification are in considerable contradiction with regard to the required environmental conditions. Nitrification requires oxygen and CO2. Denitrification only takes place in the absence of dissolved oxygen and with a sufficient supply of oxidizable substances.
Plant types
There are a variety of types of activated sludge plants. These include:
Package plants
There are a wide range of types of package plants, often serving small communities or industrial plants that may use hybrid treatment processes often involving the use of aerobic sludge to treat the incoming sewage. In such plants the primary settlement stage of treatment may be omitted. In these plants, a biotic floc is created which provides the required substrate. Package plants are designed and fabricated by specialty engineering firms in dimensions that allow for their transportation to the job site in public highways, typically width and height of . Length varies with capacity with larger plants being fabricated in pieces and welded on site. Steel is preferred over synthetic materials (e.g., plastic) for its durability. Package plants are commonly variants of extended aeration, to promote the "fit and forget" approach required for small communities without dedicated operational staff. There are various standards to assist with their design.
To use less space, treat difficult waste, and intermittent flows, a number of designs of hybrid treatment plants have been produced. Such plants often combine at least two stages of the three main treatment stages into one combined stage. In the UK, where a large number of wastewater treatment plants serve small populations, package plants are a viable alternative to building a large structure for each process stage. In the US, package plants are typically used in rural areas, highway rest stops and trailer parks.
Package plants may be referred to as high charged or low charged. This refers to the way the biological load is processed. In high charged systems, the biological stage is presented with a high organic load and the combined floc and organic material is then oxygenated for a few hours before being charged again with a new load. In the low charged system the biological stage contains a low organic load and is combined with flocculate for longer times.
Oxidation ditch
In some areas, where more land is available, sewage is treated in large round or oval ditches with one or more horizontal aerators typically called brush or disc aerators which drive the mixed liquor around the ditch and provide aeration. These are oxidation ditches, often referred to by manufacturer's trade names such as Pasveer, Orbal, or Carrousel. They have the advantage that they are relatively easy to maintain and are resilient to shock loads that often occur in smaller communities (i.e. at breakfast time and in the evening).
Oxidation ditches are installed commonly as 'fit & forget' technology, with typical design parameters of a hydraulic retention time of 24 – 48 hours, and a sludge age of 12 – 20 days. This compares with nitrifying activated sludge plants having a retention time of 8 hours, and a sludge age of 8 – 12 days.
Deep shaft / Vertical treatment
Where land is in short supply sewage may be treated by injection of oxygen into a pressured return sludge stream which is injected into the base of a deep columnar tank buried in the ground. Such shafts may be up to deep and are filled with sewage liquor. As the sewage rises the oxygen forced into solution by the pressure at the base of the shaft breaks out as molecular oxygen providing a highly efficient source of oxygen for the activated sludge biota. The rising oxygen and injected return sludge provide the physical mechanism for mixing of the sewage and sludge. Mixed sludge and sewage is decanted at the surface and separated into supernatant and sludge components. The efficiency of deep shaft treatment can be high.
Surface aerators are commonly quoted as having an aeration efficiency of 0.5–1.5 kg O2/kWh (1.1–3.3 lb O2/kWh), diffused aeration as 1.5–2.5 kg O2/kWh (3.3–5.5 lb O2/kWh). Deep Shaft claims 5–8 kg O2/kWh (11–18 lb O2/kWh).
However, the costs of construction are high. Deep Shaft has seen the greatest uptake in Japan, because of the land area issues. Deep Shaft was developed by ICI, as a spin-off from their Pruteen process. In the UK it is found at three sites: Tilbury, Anglian water, treating a wastewater with a high industrial contribution; Southport, United Utilities, because of land space issues; and Billingham, ICI, again treating industrial effluent, and built (after the Tilbury shafts) by ICI to help the agent sell more.
DeepShaft is a patented, licensed, process. The licensee has changed several times and currently (2015) Noram Engineering sells it.
Surface-aerated basins
Most biological oxidation processes for treating industrial wastewaters have in common the use of oxygen (or air) and microbial action. Surface-aerated basins achieve 80 to 90% removal of BOD with retention times of 1 to 10 days. The basins may range in depth from and utilize motor-driven aerators floating on the surface of the wastewater.
In an aerated basin system, the aerators provide two functions: they transfer air into the basins required by the biological oxidation reactions, and they provide the mixing required for dispersing the air and for contacting the reactants (that is, oxygen, wastewater and microbes). Typically, the floating surface aerators are rated to deliver the amount of air equivalent to 1.8 to 2.7 kilograms O2/kWh (4.0 to 6.0 lb O2/kWh). However, they do not provide as good mixing as is normally achieved in activated sludge systems and therefore aerated basins do not achieve the same performance level as activated sludge units.
Biological oxidation processes are sensitive to temperature and, between , the rate of biological reactions increase with temperature. Most surface aerated vessels operate at between .
Sequencing batch reactors (SBRs)
Sequencing batch reactors (SBRs) treat wastewater in batches within the same vessel. This means that the bioreactor and final clarifier are not separated in space but in a timed sequence. The installation consists of at least two identically equipped tanks with a common inlet, which can be alternated between them. While one tank is in settle/decant mode the other is aerating and filling.
Aeration methods
Diffused aeration
Sewage liquor is run into deep tanks with diffuser grid aeration systems that are attached to the floor. These are like the diffused airstone used in tropical fish tanks but on a much larger scale. Air is pumped through the blocks and the curtain of bubbles formed both oxygenates the liquor and also provides the necessary mixing action. Where capacity is limited or the sewage is unusually strong or difficult to treat, oxygen may be used instead of air. Typically, the air is generated by some type of air blower.
Surface aerators (cones)
Vertically mounted tubes of up to diameter extending from just above the base of a deep concrete tank to just below the surface of the sewage liquor. A typical shaft might be high. At the surface end, the tube is formed into a cone with helical vanes attached to the inner surface. When the tube is rotated, the vanes spin liquor up and out of the cones drawing new sewage liquor from the base of the tank. In many works, each cone is located in a separate cell that can be isolated from the remaining cells if required for maintenance. Some works may have two cones to a cell and some large works may have 4 cones per cell.
Pure oxygen aeration
Pure oxygen activated sludge aeration systems are sealed-tank reactor vessels with surface aerator type impellers mounted within the tanks at the oxygen carbon liquor surface interface. The amount of oxygen entrainment, or DO (Dissolved Oxygen), can be controlled by a weir adjusted level control, and a vent gas oxygen controlled oxygen feed valve. Oxygen is generated on site by cryogenic distillation of air, pressure swing adsorption, or other methods. These systems are used where wastewater plant space is at a premium and high sewage throughput is required as high energy costs are involved in purifying oxygen.
Recent developments
A new development of the activated sludge process is the Nereda process which produces a granular sludge that settles very well (the sludge volume index is reduced from ). A new process reactor system is created to take advantage of this quick settling sludge and is integrated into the aeration tank instead of having a separate unit outside. As of 2015, about 30 Nereda wastewater treatment plants worldwide were operational, under construction or under design, varying in size from 5,000 up to 858,000 person equivalent.
Issues
Process upsets
Sludge bulking can occur which makes activated sludge difficult to settle and frequently has an adverse impact on final effluent quality. Treating sludge bulking and managing the plant to avoid a recurrence requires skilled management and may require full-time staffing of a works to allow immediate intervention.
The discharge of toxic industrial pollution to treatment plants designed primarily to treat domestic sewage can create process upsets.
Costs and technology choice
The activated sludge process is an example for a more high-tech, energy intensive or "mechanized" process that is relatively expensive compared to some other wastewater treatment systems. It can provide a very high level of treatment.
Activated sludge plants are wholly dependent on an electrical supply to power the aerators to transfer settled solids back to the aeration tank inlet, and in many cases to pump waste sludge and final effluent. In some works untreated sewage is lifted by pumps to the head-works to provide sufficient fall through the works to enable a satisfactory discharge head for the final effluent. Alternative technologies such as trickling filter treatment requires much less power and can operate on gravity alone.
History
The activated sludge process was discovered in 1913 in the United Kingdom by two engineers, Edward Ardern and W.T. Lockett, who were conducting research for the Manchester Corporation Rivers Department at Davyhulme Sewage Works. In 1912, Gilbert Fowler, a scientist at the University of Manchester, observed experiments being conducted at the Lawrence Experiment Station at Massachusetts involving the aeration of sewage in a bottle that had been coated with algae. Fowler's engineering colleagues, Ardern and Lockett, experimented on treating sewage in a draw-and-fill reactor, which produced a highly treated effluent. They aerated the waste-water continuously for about a month and were able to achieve a complete nitrification of the sample material. Believing that the sludge had been activated (in a similar manner to activated carbon) the process was named activated sludge. Not until much later was it realized that what had actually occurred was a means to concentrate biological organisms, decoupling the liquid retention time (ideally, low, for a compact treatment system) from the solids retention time (ideally, fairly high, for an effluent low in BOD5 and ammonia.)
Their results were published in their seminal 1914 paper, and the first full-scale continuous-flow system was installed at Worcester two years later. In the aftermath of the First World War the new treatment method spread rapidly, especially to the US, Denmark, Germany and Canada. By the late 1930s, the activated sludge treatment became a well-known biological wastewater treatment process in those countries where sewer systems and sewage treatment plants were common.
See also
Activated sludge model
Aerated lagoon
Aerobic granulation
Aerobic granular reactor
Aerobic treatment system
Industrial wastewater treatment
List of wastewater treatment technologies
Membrane bioreactor
Rotating biological contactor
Sludge bulking
Thermal hydrolysis
References
Sewerage
Environmental engineering
Chemical engineering | Activated sludge | Chemistry,Engineering,Environmental_science | 5,116 |
22,153,060 | https://en.wikipedia.org/wiki/Insufflation%20%28medicine%29 | Insufflation () is the act of blowing something (such as a gas, powder, or vapor) into a body cavity. Insufflation has many medical uses, most notably as a route of administration for various drugs.
Medical uses
Surgery
Gases are often insufflated into a body cavity to inflate the cavity for more workroom, e.g. during laparoscopic surgery. The most common gas used in this manner is carbon dioxide, because it is non-flammable, colorless, and dissolves readily in blood.
Diagnostics
Gases can be insufflated into parts of the body to enhance radiological imaging or to gain access to areas for visual inspection (e.g. during colonoscopy).
Respiratory assistance
Oxygen can be insufflated into the nose by nasal cannulae to assist in respiration.
Mechanical insufflation-exsufflation simulates a cough and assists airway mucus clearance. It is used with patients with neuromuscular disease and muscle weakness due to central nervous system injury.
Glossopharyngeal insufflation is a breathing technique that consists of gulping boluses of air into the lungs. It is also used by breath-hold divers to increase their lung volumes.
Positive airway pressure is a mode of mechanical or artificial ventilation based on insufflation.
Pump inhalers for asthmatics deliver aerosolized drugs into the lungs via the mouth. However, the insufflation by the pump is not adequate for delivery to the lungs, necessitating an active inhalation by the patient.
Anesthesia and critical care
Insufflated gases and vapors are used to ventilate and oxygenate patients (oxygen, air, helium), and to induce, assist in or maintain general anaesthesia (nitrous oxide, xenon, volatile anesthetic agents).
Positive airway pressure is a mode of mechanical or artificial ventilation based on insufflation.
Nasal drug administration
Nasal insufflation is the most common method of nasal administration. Other methods are nasal inhalation and nasal instillation. Drugs administered in this way can have a local effect or a systemic effect. The time of onset for systemic drugs delivered via nasal administration is generally only marginally slower than if given intravenously.
Examples of drugs given
Steroids (local effect) and anti-asthma medication
Hormone replacement
Decongestants (local effect)
Nicotine replacement
Migraine medication
Vaccines
Nasal administration can also be used for treatment of children or patients who are otherwise alarmed or frightened by needles, or where intravenous (IV) access is unavailable.
History
In the 18th century, the tobacco smoke enema, an insufflation of tobacco smoke into the rectum, was a common method of reviving drowning victims.
References
Medical terminology
Routes of administration | Insufflation (medicine) | Chemistry | 588 |
3,133,127 | https://en.wikipedia.org/wiki/F%C3%A1ry%E2%80%93Milnor%20theorem | In the mathematical theory of knots, the Fáry–Milnor theorem, named after István Fáry and John Milnor, states that three-dimensional smooth curves with small total curvature must be unknotted. The theorem was proved independently by Fáry in 1949 and Milnor in 1950. It was later shown to follow from the existence of quadrisecants .
Statement
If K is any closed curve in Euclidean space that is sufficiently smooth to define the curvature κ at each of its points, and if the total absolute curvature is less than or equal to 4π, then K is an unknot, i.e.:
The contrapositive tells us that if K is not an unknot, i.e. K is not isotopic to the circle, then the total curvature will be strictly greater than 4π. Notice that having the total curvature less than or equal to 4 is merely a sufficient condition for K to be an unknot; it is not a necessary condition. In other words, although all knots with total curvature less than or equal to 4π are the unknot, there exist unknots with curvature strictly greater than 4π.
Generalizations to non-smooth curves
For closed polygonal chains the same result holds with the integral of curvature replaced by the sum of angles between adjacent segments of the chain. By approximating arbitrary curves by polygonal chains, one may extend the definition of total curvature to larger classes of curves, within which the Fáry–Milnor theorem also holds (, ).
References
.
.
.
.
External links
. Fenner describes a geometric proof of the theorem, and of the related theorem that any smooth closed curve has total curvature at least 2π.
Knot theory
Theorems in topology | Fáry–Milnor theorem | Mathematics | 358 |
4,211,895 | https://en.wikipedia.org/wiki/Center%20for%20Auto%20Safety | The Center for Auto Safety is a Washington, D.C.–based 501(c)(3) consumer advocacy non-profit group focused on the automotive industry in the United States. Founded in 1970 by Consumers Union and Ralph Nader, the group focuses its efforts on enacting reform though public advocacy and pressuring the National Highway Traffic Safety Administration and automakers through litigation.
For decades, it was led by Executive Director Clarence Ditlow, who died in late 2016 from cancer. Ditlow was widely admired in the auto safety community, although he also had detractors among auto manufacturers. The Center for Auto Safety is currently led by Executive Director Jason Levine.
History
The Center for Auto Safety (the Center) was founded in 1970 by Consumers Union and Ralph Nader as a consumer safety group to protect drivers. Ralph Nader, the author of Unsafe at Any Speed, believed that automakers and the government were not adequately regulating safety. For many years, the Center was led by Clarence Ditlow, a well-known consumer safety advocate. The Center has advocated vigorously for driver safety and automaker accountability by pressuring government agencies and automakers with many lawsuits campaigns. The Center has also published The Car Book annually, which presents the latest safety ratings, dealer prices, fuel economy, insurance premiums, and maintenance costs for new vehicles.
Lemon laws
The Center for Auto Safety counts the enacting of lemon laws in all 50 states among its greatest successes. The Center has testified over 50 times before Congressional Committees on auto safety, warranties and service bulletins, air pollution, consumer protection, and fuel economy. The Center was the leading consumer advocate in passage of Magnuson-Moss Warranty Act, fuel economy provisions of Energy Policy and Conservation Act and Technical Service Bulletin disclosure in MAP-21. The Center recently succeeded in a lawsuit against DOT Secretary Anthony Foxx, forcing NHTSA to make public all manufacturer communications to dealers regarding safety issues. Additionally, former Center Executive Director Clarence Ditlow and Ralph Nader published The Lemon Book in 1980 to educate drivers on how to avoid buying a "lemon" and what to do if they purchase one.
Recalls
The Center for Auto Safety has been involved in many campaigns to pressure automakers and NHTSA to issue recalls on dangerous car parts. Throughout its history, the Center has played a major role in numerous recalls including 6.7 million Chevrolets for defective engine mounts, 15 million Firestone 500 tires, 1.5 million Ford Pintos for exploding gas tanks, 3 million Evenflo child seats for defective latches. More recently, the Center was the main proponent for recalls of 7 million Toyotas for sudden acceleration, 2 million Jeeps for fuel tank fires, 11 million GM vehicles for defective ignition switches, and over 60 million exploding Takata airbag inflators.
Accomplishments
The Center for Auto Safety counts numerous far-reaching efforts among its successes:
"Lemon laws" enacted in all 50 states
State laws requiring auto manufacturers to disclose "hidden" warranties to consumers
The Firestone tire recall
The Ford Pinto recall due to its dangerous gas tank design
Exposure of a potentially lethal gas tank design in General Motors pickup trucks
Improved U.S. highway safety standards administered by the U.S. National Highway Traffic Safety Administration (NHTSA)
Recall of Jeep vehicles with fuel tanks that could explode in rear impact
Pressuring General Motors to take action on their faulty airbags and ignition switches
Annual publication of The Car Book to inform drivers of the safety of specific models
Better protection for drivers against rollover and roof crush in SUVs
Maintaining an online database of vehicle safety complaints submitted to the Center
Wrote Small—On Safety: The Designed-in Dangers of the Volkswagen.
References
External links
The Center for Auto Safety—Official website
The Safe Climate Campaign—Official website
1970 establishments in Washington, D.C.
Automotive safety
Consumer rights organizations
Organizations established in 1970
Political advocacy groups in the United States
Ralph Nader | Center for Auto Safety | Physics | 792 |
18,184,222 | https://en.wikipedia.org/wiki/David%20Caminer | David Caminer OBE (26 June 1915 – 19 June 2008) was a British computer engineer who helped to develop the world's first business computer, LEO (Lyons Electronic Office). He has been called "the world's first corporate electronic systems analyst" and "the world's first software engineer". He carried out the systems analysis and charting for the world's first routine business computer job, thus he is also called "the first business application programmer".
Life and work
Caminer was born David Treisman in the East End of London. His father was killed in action during the First World War. When his mother remarried, he was given his stepfather's surname Caminer.
In March 1943 Caminer lost a leg at the Battle of Mareth, whilst serving with the Green Howards in Tunisia.
Caminer worked generally in the area of operations management and cost accounting. He helped to design, along with John Pinkerton, the LEO (Lyons Electronic Office), which has been certified by the Guinness World Records as the world's first business computer.
Caminer joined Lyons & Co. as a management trainee in 1936 and became manager of the Lyons Systems Research Office before concentrating on the computer innovation. He became director of LEO Computers Ltd in 1959 and was subsequently general sales manager of English Electric LEO Marconi, while retaining his responsibility for consultancy and systems implementation. After the merger to form ICL, his posts included the delineation of the systems software requirements for the New Range and director of New Range Market Introduction.
He chose to complete his formal career in the field as project director for the implementation of the computer and communications network for the European Economic Community, where he developed a computer system for the European Common Market. For this work he was appointed to the Order of the British Empire in 1980.
As Caminer himself pointed out, the LEO story highlights important characteristics of the history of innovation in computing technology, including the complex roles of government funding and university research; the frequent failure of technically advanced products to enjoy commercial success; the importance for commercial success in business computing of firm-level capabilities in related technologies; and the interaction between organizational and technological change in the adoption of business computing systems.
In 2001 he presented the second IEE Pinkerton Lecture.
He died in June 2008, at age 92.
See also
LEO (computer)
List of pioneers in computer science
References
Notes
The Journal of Strategic Information Systems, Volume 12, Issue 4, December 2003, Pages 265-284 LEO Conference 2001
David C. Mowery, 50 Years of business computing: LEO to Linux, The Journal of Strategic Information Systems, Volume 12, Issue 4, December 2003, Pages 295-308
Ferry, G. (2004). A Computer Called LEO: Lyons Tea Shops and the World's First Office Computer. Hammersmith: Harper Perennial. .
Bird, P.J. (1994). LEO: The First Business Computer''. Wokingham: Hasler Publishing Co. .
External links
Times obituary
Financial Times (London) obituary
Telegraph obituary
The Guardian obituary
1915 births
2008 deaths
History of computing in the United Kingdom
Officers of the Order of the British Empire
British Army personnel of World War II
British computer specialists | David Caminer | Technology | 645 |
20,541,712 | https://en.wikipedia.org/wiki/PITZ | The Photo Injector Test Facility at the DESY location in Zeuthen (PITZ) was built in 2002 in order to test and optimize sources of high-brightness electron beams for future free-electron lasers (FELs) and linear colliders. The focus at PITZ is on the production of intense electron beams with very small transverse emittance and reasonably small longitudinal emittance which are required in order to meet the high-gain conditions of FEL operation. This challenge is met by applying the most advanced techniques in combination with key parameters of projects based on TESLA technology, such as FLASH and the European XFEL. The PITZ collaboration involves several accelerator centres and institutes from around the world.
References
External links
PITZ website
DESY website
FLASH website
European XFEL website
Experimental particle physics | PITZ | Physics | 167 |
24,412,778 | https://en.wikipedia.org/wiki/Glossomastix | Glossomastix is a genus of heterokont.
It includes a single species, Glossomastix chrysoplasta.
References
Ochrophyta
Ochrophyte genera
Monotypic algae genera | Glossomastix | Biology | 45 |
42,968,488 | https://en.wikipedia.org/wiki/BMVA%20Summer%20School | BMVA Summer School is an annual summer school on computer vision, organised by the British Machine Vision Association and Society for Pattern Recognition (BMVA). The course is residential, usually held over five days, and consists of lectures and practicals in topics in image processing, computer vision, pattern recognition. It is intended that the course will complement and extend the material in existing technical courses that many students/researchers will encounter in their early stage of postgraduate training or careers. It aims to broaden awareness of knowledge and techniques in Vision, Image Computing and Pattern Recognition, and to develop appropriate research skills, and for students to interact with their peers, and to make contacts among those who will be the active researchers of their own generation. It is open to students from both UK and non-UK universities. The registration fees vary based on time of registration and are in general slightly higher for non-UK students. The summer school has been hosted locally by various universities in UK that carry out Computer Vision research, e.g., Kingston University, the University of Manchester, Swansea University and University of Lincoln.
It has run since the mid-1990s, and content is updated every year. Speakers at the Summer School are active academic researchers or experienced practitioners from industry, mainly in the UK. It has received financial support from EPSRC from 2009 to 2012.
Delegates of the summer school are usually encouraged to bring posters to summer school to present their work to peers and lecturers. A best poster is selected by the summer school lecturers.
References
External links
26th BMVA Summer School 2023, University of East Anglia
25th BMVA Summer School 2022, University of East Anglia
2017 BMVA summer school, University of Lincoln
2015-16 BMVA summer school, Swansea University
2014 BMVA summer school, Swansea University
2013 BMVA summer school, Manchester University
2012 BMVA summer school, Manchester University
2011 BMVA summer school, Manchester University
Annual events in the United Kingdom
Computer science education in the United Kingdom
Computer vision research infrastructure
Engineering and Physical Sciences Research Council
Information technology organisations based in the United Kingdom
Machine vision
Summer schools | BMVA Summer School | Engineering | 429 |
21,846,856 | https://en.wikipedia.org/wiki/Architectural%20History%20%28journal%29 | Architectural History is an annual peer-reviewed journal published by the Society of Architectural Historians of Great Britain (SAHGB).
The journal is published each autumn. The architecture of the British Isles is a major theme of the journal, but articles can consider all places and periods. All members of the SAHGB receive the journal, as do subscribing institutional libraries. Older issues from its inception in 1958 onwards are available online through JSTOR.
The editor-in-chief is Alistair Fair, of the University of Cambridge.
References
External links
Academic journals established in 1958
1958 establishments in the United Kingdom
Architectural history journals
Annual journals
English-language journals
Cambridge University Press academic journals | Architectural History (journal) | Engineering | 136 |
20,162,937 | https://en.wikipedia.org/wiki/BLU-80/B%20Bigeye%20bomb | The BLU-80/B BIGEYE bomb was a developmental U.S. air-launched binary chemical weapon. The BIGEYE was a class glide bomb with a radar altimeter fuze intended to disperse the binary generated nerve agent VX, made in flight from the non-lethal chemical components "QL" and sulfur only after aircraft release. The BLU-80-B was designed under the auspices of the U.S. Navy as a safe chemical weapons alternative in response to chemical weapons (CW) threats from the USSR and other actors. BIGEYE was a genuine tri-service program led by the U.S. Navy with significant U.S. Army and U.S. Air Force participation. Initially approved in the 1950s, the program persisted into the 1990s.
Background
As the stockpile of U.S. unitary (live agent) chemical weapons began to show troubling leakage, the Department of Defense (DoD) became acutely aware of the safety hazard to military personnel and public backlash this could generate. It is now known that the Soviets experienced the same and likely worse leakage issues with their unitary live agent weapons. With this in mind, the Pentagon insisted that it needed a binary chemical weapons program to counter and deter a Soviet Union or third-world chemical attack threat.
The U.S. Army Chemical Corps was reactivated in 1976 to assess and deal with this threat, and with it came the increased desire to acquire a retaliatory chemical capability in the form of much safer binary chemical weapons. Initially, the United States was in Strategic Arms Limitation Talks with the Soviet Union, and then-President Jimmy Carter rejected U.S. Army requests for authorization of the binary chemical weapons program. The talks deteriorated, and President Carter eventually granted the Army request. However, at the last minute Carter pulled the provision from the budget. This action left the decision on a retaliatory binary chemical weapons option to the Ronald Reagan administration.
History
BIGEYE (an acronym for Binary Internally Generated chemical weapon within the "EYE" series of canister weapons) was the common name for the BLU-80/B, a concept conceived during the 1950s. During the 1970s at Pine Bluff Arsenal around 200 test articles were produced. Initial production contracts for the BIGEYE were awarded in June, 1988, to The Marquardt Company of Van Nuys, CA, the project's prime contractor for most of the program. The original timeline for the U.S. binary chemical weapons program called for the BIGEYE to be deployed by September 1988. President Reagan authorized the spending of more than $59 million in 1986 to revive the binary chemical weapons program. Under the original timeline, the BIGEYE was to be the second binary chemical weapon to be produced (the first being a binary artillery shell) with binary chemical agent rockets to follow. After a General Accounting Office (GAO) report pointed out numerous flaws in the program the U.S. Senate moved to effectively kill the binary chemical weapons program, including the BIGEYE bomb. In 1989 President George H. W. Bush announced that the U.S. would retain the option to produce such binary weapons. At the time of his announcement, 1992 was the earliest date BIGEYES were expected to be deployed.
Specifications
The BIGEYE was an air-launched 500 pound-class canister weapon to be delivered by various U.S. Navy and Air Force aircraft. The interior of the weapon consisted of two separate containers of non-lethal chemical compounds, stored separately and assembled only immediately before flight, and then combined to create the active chemical nerve agent VX only after release from the aircraft. It was the storage separation of less aggressive chemical components that ensured safe storage/handling and simpler maintenance requirements. The bomb was a Navy weapon design that would atomize the percutaneous nerve agent VX over a targeted area by releasing the binary-generated agent while gliding through the air over the target.
The BIGEYE bomb weighed ; and would have generated the chemical agent VX. It was to have a length of and a diameter of . The glide bomb had a wingspan of . The BIGEYE was not planned to have any internal guidance, propulsion or autopilot systems (hence its "glide bomb" designation).
Problems and issues
The 25+ year old, on-again off-again BIGEYE bomb program was plagued with problems and controversy from its outset. Much of the controversy was based on analysis by the Government Accountability Office (GAO). Also criticized was the entire idea of a modern American chemical weapons program. Such a program, the argument went, would actually encourage others to develop chemical weapons, as opposed to acting as a deterrent.
The testing, which had mixed results, presented its own set of problems. In 1987 the Navy and Air Force conducted 70+ tests, results which were characterized as "very inconsistent" by the GAO. Following a test suspension and subsequent significant design improvements, vastly better weapons function and reliability results were achieved. Problems the Navy encountered with the BIGEYE included excessive pressure build-up, questions about the lethality of the chemical mixture resulting from variable mix times, and overall reliability concerns. Scientists debated the efficacy of the binary weapons program, especially since the BIGEYE had only been tested using simulants.
In the end, the BLU-80/B BIGEYE binary chemical weapon might possibly have been the tipping point in chemical weapons disarmament talks with the USSR, as the Soviets agreed to significant chemical weapons disarmament agreements immediately after successful operational test results of the BIGEYE resulting from improvements implemented by the U.S. Navy's Naval Air Weapons Center, China Lake.
Notes
Chemical weapon delivery systems
Cold War aerial bombs of the United States
Chemical weapons of the United States | BLU-80/B Bigeye bomb | Chemistry | 1,158 |
2,049,553 | https://en.wikipedia.org/wiki/IReview | iReview was a service offered by Apple Computer (now Apple Inc.) dedicated to reviews of Internet content. During the 2000 Macworld Conference in San Francisco, Apple CEO Steve Jobs introduced this service along with iTools, which was the free predecessor to Apple's current iCloud subscription service.
iReview was part of a reaction to the commercial success of the iMac that resulted in thousands of new computer owners suddenly having access to the Internet. The main purpose of the service was to give new users a place for detailed reviews on websites on the World Wide Web. iReview was integrated into the Apple website as part of the new "tabbed" layout, with a dedicated tab alongside iCards, iTools, the online store, QuickTime, and online support. Once a visitor clicked on the iReview tab, they could choose from one of 15 categories of websites for specific reviews on subjects that may be of interest. Each initial review was published by Apple employees, who gave their input on the site along with a detailed review and an overall rating. Visitors to iReview were also able to review and rate the sites themselves as well. Users could organize the viewing of reviews by ratings or by simple searches.
Cancellation
In February 2001, Apple cancelled the iReview service. Its failure to generate traffic is generally attributed to a lack of awareness of the service by most web users, a lack of perceived openness of the system, and the idea that most people would typically not spend time reading others' opinions of websites when they could quickly generate their own opinions by visiting the sites themselves.
References
Apple Inc. services
Recommender systems | IReview | Technology | 339 |
1,344,480 | https://en.wikipedia.org/wiki/Uniform%20isomorphism | In the mathematical field of topology a uniform isomorphism or is a special isomorphism between uniform spaces that respects uniform properties. Uniform spaces with uniform maps form a category. An isomorphism between uniform spaces is called a uniform isomorphism.
Definition
A function between two uniform spaces and is called a uniform isomorphism if it satisfies the following properties
is a bijection
is uniformly continuous
the inverse function is uniformly continuous
In other words, a uniform isomorphism is a uniformly continuous bijection between uniform spaces whose inverse is also uniformly continuous.
If a uniform isomorphism exists between two uniform spaces they are called or .
Uniform embeddings
A is an injective uniformly continuous map between uniform spaces whose inverse is also uniformly continuous, where the image has the subspace uniformity inherited from
Examples
The uniform structures induced by equivalent norms on a vector space are uniformly isomorphic.
See also
— an isomorphism between topological spaces
— an isomorphism between metric spaces
References
, pp. 180-4
Homeomorphisms
Uniform spaces | Uniform isomorphism | Mathematics | 206 |
25,306,829 | https://en.wikipedia.org/wiki/Terzan%205 | Terzan 5 is a heavily obscured globular cluster belonging to the bulge (the central star concentration) of the Milky Way galaxy. It was one of six globulars discovered by French astronomer Agop Terzan in 1968 and was initially labeled Terzan 11. The cluster was cataloged by the Two-Micron Sky Survey as IRC–20385. It is situated in the Sagittarius constellation in the direction of the Milky Way's center. Terzan 5 probably follows an unknown complicated orbit around the center of the galaxy, but currently it is moving towards the Sun with a speed of around 90 km/s.
Physical properties
The absolute magnitude of Terzan 5 is at least . Its bolometric luminosity is about 800,000 times that of the Sun, while its mass is about 2 million solar masses. The small core of Terzan 5—about 0.5 pc in size—has one of the highest star densities in the galaxy. Its volume mass density exceeds , while its volume luminosity density exceeds , where and are the Sun's mass and luminosity, respectively. The cluster also has one of the highest metallicities among the Milky Way's globular clusters—[Fe/H]=−0.21.
In 2009 it was discovered that Terzan 5 consists of at least two generations of stars with ages of 12 and 4.5 billion years and slightly different metallicities, possibly indicating that it is the core of a disrupted dwarf galaxy, not a true globular cluster. There are only a few other globular clusters in the Milky Way that contain stars with different ages. Among them are M54, Omega Centauri and Liller 1. The latter, like Terzan 5, is thought to be a fossil fragment from the assembly of the galactic bulge. The cluster also contains around 1300 core helium burning horizontal branch (HB) stars, including at least one RR Lyrae variable star.
Pulsars and X-ray sources
Terzan 5 is known to contain 49 millisecond radio pulsars as of December 2023, the largest MSP population among all globular clusters in the Galaxy; their true number may be as high as 200. The first such object, PSR B1744-24A, discovered in 1990, has the period of 11.56 ms. The population of pulsars inside Terzan 5 includes PSR J1748–2446ad, the fastest known millisecond pulsar, which is spinning at 716 Hz (the rotation period is 1.40 ms).
Terzan 5 also contains an X-ray burster, discovered in 1980, known as Terzan 5 or XB 1745-25. It also contains around 50 weaker X-ray sources, many of which are likely Low-mass X-ray binaries (LMXB) or cataclysmic variables.
The large number of X-ray sources and millisecond pulsars may be a direct consequence of the high density of the cluster's core, which leads to a high rate of star collisions, and to formation of close binaries, including binary systems which contain a neutron star.
In addition to discrete X-ray sources Terzan 5 produces a diffuse non-thermal X-ray emission and high (a few GeV) and ultra-high (0.5–24 TeV) energy gamma-rays. The high energy gamma rays probably originate in the magnetosphere of abundant millisecond pulsars, while ultra-high energy gamma rays likely result from the inverse Compton scattering by the relativistic electron emitted by the pulsars off the cosmic microwave background radiation.
Gallery
Notes
References
Terzan 05
Sagittarius (constellation) | Terzan 5 | Astronomy | 775 |
1,461,142 | https://en.wikipedia.org/wiki/Ecotope | Ecotopes are the smallest ecologically distinct landscape features in a landscape mapping and classification system. As such, they represent relatively homogeneous, spatially explicit landscape functional units that are useful for stratifying landscapes into ecologically distinct features for the measurement and mapping of landscape structure, function and change.
Like ecosystems, ecotopes are identified using flexible criteria, in the case of ecotopes, by criteria defined within a specific ecological mapping and classification system. Just as ecosystems are defined by the interaction of biotic and abiotic components, ecotope classification should stratify landscapes based on a combination of both biotic and abiotic factors, including vegetation, soils, hydrology, and other factors. Other parameters that must be considered in the classification of ecotopes include their period of stability (such as the number of years that a feature might persist), and their spatial scale (minimum mapping unit).
The first definition of ecotope was made by Thorvald Sørensen in 1936. Arthur Tansley picked this definition up in 1939 and elaborated it. He stated that an ecotope is "the particular portion, [...], of the physical world that forms a home for the organisms which inhabit it". In 1945 Carl Troll first applied the term to landscape ecology "the smallest spatial object or component of a geographical landscape". Other academics clarified this to suggest that an ecotope is ecologically homogeneous and is the smallest ecological land unit that is relevant.
The term "patch" was used in place of the term "ecotope", by Foreman and Godron (1986), who defined a patch as "a nonlinear surface area differing in appearance from its surroundings". However, by definition, ecotopes must be identified using a full suite of ecosystem characteristics: patches are a more general type of spatial unit than ecotopes.
In ecology an ecotope has also been defined as "The species relation to the full range of environmental and biotic variables affecting it" (Whittaker et al., 1973), but the term is rarely used in this context, due to confusion with the ecological niche concept.
See also
Biotope
Ecotype
References
Bibliography
Bastian, O., C. Beierkuhlein, H. J. Klink, J. Löfffler, U. Steinhardt, M. Volk, and M. Wilmking. 2003. Landscape structures and processes. Pages 49–112 in O. Bastian and U. Steinhardt, eds. Development and Perspectives of Landscape Ecology. Kluwer Academic Publishers.
Farina, A. 1998. Principles and Methods in Landscape Ecology. Chapman & Hall, London; New York.
Foreman, R. and Godron, M. 1986. Landscape Ecology. Wiley, New York.
Haber, W. 1994. System ecological concepts for environmental planning. Pages 49–67 in F. Klijn, ed. Ecosystem Classification for Environmental Management. Kluwer Academic Publishers, Dordrecht, The Netherlands.
Ingegnoli, V. 2002. Landscape Ecology - a Widening Foundation: A Holistic Unifying Approach. Springer, Berlin; New York.
Klijn, F., and H. A. Udo De Haes. 1994. A hierarchical approach to ecosystems and its implications for ecological land classification. Landscape Ecology 9: 89-104.
Schmithüsen, J. 1948. "Fliesengefüge der Landschaft" und "Ökotop": Vorschläge zur begrifflichen Ordnung und zur Nomenklatur in der Landschaftsforschung. Berichte zur Deutschen Landeskunde (Bad Godesberg) 5: 74-83.
Tansley, A. G. 1939. The British Isles and Their Vegetation. Vol. 1 of 2. Cambridge, United Kingdom. 494 pp.
Troll, C. 1950. Die geografische landschaft und ihre erforschung. Pages 163-181. Studium Generale 3. Springer, Heidelberg, German Democratic Republic.
Whittaker, R. H., S. A. Levin, and R. B. Root. 1973. Niche, habitat, and ecotope. American Naturalist 107: 321-338.
Zonneveld, I. S. 1989. The land unit - A fundamental concept in landscape ecology, and its applications. Landscape Ecology 3: 67-86.
External links
A set of different definitions of the term "ecotope"
Ecotope at Encyclopedia of Earth
Ecosystems | Ecotope | Biology | 939 |
43,106,032 | https://en.wikipedia.org/wiki/C16H16O4 | {{DISPLAYTITLE:C16H16O4}}
The molecular formula C16H16O4 (molar mass: 272.29 g/mol, exact mass: 272.104859 u) may refer to:
Gnetucleistol E
1,6-Bis(2,3-epoxypropoxy)naphthalene
Molecular formulas | C16H16O4 | Physics,Chemistry | 82 |
61,900,989 | https://en.wikipedia.org/wiki/Magic%20wavelength | The magic wavelength (also known as a related quantity, magic frequency) is the wavelength of an optical lattice where the polarizabilities of two atomic clock states have the same value, such that the AC Stark shift caused by the laser intensity fluctuation has no effect on the transition frequency between the two clock states.
AC Stark shift by optical lattice
The laser field in an optical lattice induces an electric dipole moment in the atoms to exert forces on them and hence confine them. However, the difference in polarizabilities of the atomic states leads to an AC Stark shift in the transition frequency between the two states, a shift that is dependent on the laser optical intensity at the particular atom location in the lattice. When it comes to precise measurements of transition frequency such as atomic clocks, the temporal fluctuations of the laser optical intensity would then deteriorate the clock accuracy. Furthermore, due to the spatial variation of laser intensity in the lattice, the atom's motion within the lattice would also be coupled into the uncertainty of the internal transition frequency of the atom.
Polarizability depends on wavelength
Despite having different function forms, the polarizabilities of two atomic states do have a dependency on the wavelength of the laser field. In some cases, it is then possible to find a particular wavelength at which the two atomic states happen to have exactly the same polarizability. This particular wavelength, where the AC Stark shift vanishes for the transition frequency, is called the magic wavelength, and the frequency that corresponds to this wavelength is called the magic frequency. This idea was first introduced by Hidetoshi Katori's calculation in 2003, and then experimentally achieved by Katori's group in 2005.
References
Physical quantities
Atomic clocks
Atomic physics | Magic wavelength | Physics,Chemistry,Mathematics | 350 |
45,317 | https://en.wikipedia.org/wiki/Flange | A flange is a protruded ridge, lip or rim, either external or internal, that serves to increase strength (as the flange of a steel beam such as an I-beam or a T-beam); for easy attachment/transfer of contact force with another object (as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera); or for stabilizing and guiding the movements of a machine or its parts (as the inside flange of a rail car or tram wheel, which keep the wheels from running off the rails). Flanges are often attached using bolts in the pattern of a bolt circle.
Flanges play a pivotal role in piping systems by allowing easy access for maintenance, inspection, and modification. They provide a means to connect or disconnect pipes and equipment without the need for welding, which simplifies installation and reduces downtime during repairs or upgrades. Additionally, flanges facilitate the alignment of pipes, ensuring a proper fit and minimizing stress on the system.
Plumbing or piping
A flange can also be a plate or ring to form a rim at the end of a pipe when fastened to the pipe (for example, a closet flange). A blind flange is a plate for covering or closing the end of a pipe. A flange joint is a connection of pipes, where the connecting pieces have flanges by which the parts are bolted together.
Although the word 'flange' generally refers to the actual raised rim or lip of a fitting, many flanged plumbing fittings are themselves known as flanges.
Common flanges used in plumbing are the Surrey flange or Danzey flange, York flange, Sussex flange and Essex flange.
Surrey and York flanges fit to the top of the hot water tank allowing all the water to be taken without disturbance to the tank. They are often used to ensure an even flow of water to showers. An Essex flange requires a hole to be drilled in the side of the tank.
There is also a Warix flange which is the same as a York flange but the shower output is on the top of the flange and the vent on the side. The York and Warix flange have female adapters so that they fit onto a male tank, whereas the Surrey flange connects to a female tank.
A closet flange provides the mount for a toilet.
Pipe flanges
Piping components can be bolted together between flanges. Flanges are used to connect pipes with each other, to valves, to fittings, and to specialty items such as strainers and pressure vessels. A cover plate can be connected to create a "blind flange". Flanges are joined by bolting, and sealing is often completed with the use of gaskets or other methods. Mechanical means to mitigate effects of leaks, like spray guards or specific spray flanges, may be included. Industries where flammable, volatile, toxic or corrosive substances are being processed have greater need of special protection at flanged connections.
Flange guards can provide that added level of protection to ensure safety.
There are many different flange standards to be found worldwide. To allow easy functionality and interchangeability, these are designed to have standardised dimensions. Common world standards include ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean). In the USA, the standard is ASME B16.5 (ANSI stopped publishing B16.5 in 1996). ASME B16.5 covers flanges up to 24 inches size and up to pressure rating of Class 2500. Flanges larger than 24 inches are covered in ASME B16.47.
In most cases, standards are interchangeable, as most local standards have been aligned to ISO standards; however, some local standards still differ. For example, an ASME flange will not mate against an ISO flange. Further, many of the flanges in each standard are divided into "pressure classes", allowing flanges to be capable of taking different pressure ratings. Again these are not generally interchangeable (e.g. an ASME 150 will not mate with an ASME 300).
These pressure classes also have differing pressure and temperature ratings for different materials. Unique pressure classes for piping can also be developed for a process plant or power generating station; these may be specific to the corporation, engineering procurement and construction (EPC) contractor, or the process plant owner. The ASME pressure classes for flat-face flanges are Class 125 and Class 250. The classes for ring-joint, tongue and groove, and raised-face flanges are Class 150, Class 300, Class 400 (unusual), Class 600, Class 900, Class 1500, and Class 2500.
The flange faces are also made to standardized dimensions and are typically "flat face", "raised face", "tongue and groove", or "ring joint" styles, although other obscure styles are possible.
Flange designs are available as "weld neck", "slip-on", "lap joint", "socket weld", "threaded", and also "blind".
Types of flanges
Flanges come in various types, each designed to meet specific requirements based on factors such as pressure, temperature, and application. Some common types include:
Weld Neck Flanges: Weld neck flanges feature a long tapered hub that provides reinforcement to the connection, making them suitable for high-pressure and high-temperature applications.
Slip-On Flanges: Slip-on flanges have a slightly larger diameter than the pipe they connect to and are slipped over the pipe before welding. They are commonly used in low-pressure and non-critical applications.
Socket Weld Flanges: Socket weld flanges have a recessed area (socket) into which the pipe end fits, allowing for fillet welding. They are suitable for small-bore piping systems and applications with moderate pressure and temperature requirements.
Blind Flanges: Blind flanges are solid discs used to close the end of a piping system or vessel. They are often used for pressure testing or as a permanent seal when a pipe end needs to be closed off.
ASME standards (U.S.)
Pipe flanges that are made to standards called out by ASME B16.5 or ASME B16.47, and MSS SP-44. They are typically made from forged materials and have machined surfaces. ASME B16.5 refers to nominal pipe sizes (NPS) from " to 24". B16.47 covers NPSs from 26" to 60". Each specification further delineates flanges into pressure classes: 150, 300, 400, 600, 900, 1500 and 2500 for B16.5, and B16.47 delineates its flanges into pressure classes 75, 150, 300, 400, 600, 900. However these classes do not correspond to maximum pressures in psi. Instead, the maximum pressure depends on the material of the flange and the temperature. For example, the maximum pressure for a Class 150 flange is 285 psi, and for a Class 300 flange it is 740 psi (both are for ASTM a105 carbon steel and temperatures below 100 °F).
The gasket type and bolt type are generally specified by the standard(s); however, sometimes the standards refer to the ASME Boiler and Pressure Vessel Code (B&PVC) for details (see ASME Code Section VIII Division 1 – Appendix 2). These flanges are recognized by ASME Pipe Codes such as ASME B31.1 Power Piping, and ASME B31.3 Process Piping.
Materials for flanges are usually under ASME designation: SA-105 (Specification for Carbon Steel Forgings for Piping Applications), SA-266 (Specification for Carbon Steel Forgings for Pressure Vessel Components), or SA-182 (Specification for Forged or Rolled Alloy-Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service). In addition, there are many "industry standard" flanges that in some circumstance may be used on ASME work.
The product range includes SORF, SOFF, BLRF, BLFF, WNRF (XS, XXS, STD and Schedule 20, 40, 80), WNFF (XS, XXS, STD and Schedule 20, 40, 80), SWRF (XS and STD), SWFF (XS and STD), Threaded RF, Threaded FF and LJ, with sizes from 1/2" to 16". The bolting material used for flange connection is stud bolts mated with two nut (washer when required). In petrochemical industries, ASTM A193 B7 STUD and ASTM A193 B16 stud bolts are used as these have high tensile strength.
European dimensions (EN / DIN) Hygienic Flange STC DIN11853-2
Most countries in Europe mainly install flanges according to standard DIN EN 1092-1 (forged stainless or steel flanges). Similar to the ASME flange standard, the EN 1092-1 standard has the basic flange forms, such as weld neck flange, blind flange, lapped flange, threaded flange (thread ISO7-1 instead of NPT), weld on collar, pressed collars, and adapter flange such as flange coupling GD press fittings. The different forms of flanges within the EN 1092-1 (European Norm/Euronorm) is indicated within the flange name through the type.
Similar to ASME flanges, EN1092-1 steel and stainless flanges, have several different versions of raised or none raised faces. According to the European form the seals are indicated by different form:
Furthermore, for sanitary applications such as in the food and beverage and pharmaceutical industries, sanitary flanges according to DIN 11853-2 STC are utilized. The primary distinction between sanitary flanges according to DIN 11853-2 and DIN/EN flanges lies in the restricted dead-room and the interior polishing according to hygienic levels of H1 to H4. Usually the flange traders that hold the Standard DIN EN 1092-1 such as Hage Fittings, do not hold Sanitary flanges as the storage requirements are different. Sanitary flanges are more delicate and need to stay clean. Usually the O-Rings, according to DIn 11853, are made out of FPM or EPDM.
Other countries
Flanges in the rest of the world are manufactured according to the ISO standards for materials, pressure ratings, etc. to which local standards including DIN, BS, and others, have been aligned.
Compact flanges
As the size of a compact flange increases it becomes relatively increasingly heavy and complex resulting in high procurement, installation and maintenance costs.
Large flange diameters in particular are difficult to work with, and inevitably require more space and have a more challenging handling and installation procedure, particularly on remote installations such as oil rigs.
The design of the flange face includes two independent seals. The first seal is created by application of seal seating stress at the flange heel, but it is not straight forward to ensure the function of this seal.
Theoretically, the heel contact will be maintained for pressure values up to 1.8 times the flange rating at room temperature.
Theoretically, the flange also remains in contact along its outer circumference at the flange faces for all allowable load levels that it is designed for.
The main seal is the IX seal ring. The seal ring force is provided by the elastic stored energy in the stressed seal ring. Any heel leakage will give internal pressure acting on the seal ring inside intensifying the sealing action. This however requires the IX ring to be retained in the theoretical location in the ring groove which is difficult to ensure and verify during installation.
The design aims at preventing exposure to oxygen and other corrosive agents. Thus, this prevents corrosion of the flange faces, the stressed length of the bolts and the seal ring. This however depends on the outer dust rim to remain in satisfactory contact and that the inside fluid is not corrosive in case of leaking into the bolt circle void.
Applications of compact flanges
The initial cost of the theoretical higher performance compact flange is inevitably higher than a regular flange due to the closer tolerances and significantly more sophisticated design and installation requirements.
By way of example, compact flanges are often used across the following applications: subsea oil and gas or riser, cold work and cryogenics, gas injection, high temperature, and nuclear applications.
Train wheels
Most trains and trams stay on their tracks primarily due to the conical geometry of their wheels. They also have a flange on one side to keep the wheels, and hence the train, running on the rails when the limits of the geometry-based alignment are reached, either due to some emergency or defect, or simply because the curve radius is so small that self-steering normally provided by the coned wheel tread is no longer effective.
Vacuum flanges
A vacuum flange is a flange at the end of a tube used to connect vacuum chambers, tubing and vacuum pumps to each other.
Microwave
In microwave telecommunications, a flange is a type of cable joint that allows different types of waveguide to connect.
Several different microwave RF flange types exist, such as CAR, CBR, OPC, PAR, PBJ, PBR, PDR, UAR, UBR, UDR, icp and UPX.
Ski boots
Ski boots use flanges at the toe or heel to connect to the binding of the ski. The size and shape for flanges on alpine skiing boots is standardized in ISO 5355. Traditional telemark and cross country boots use the 75 mm Nordic Norm, but the toe flange is informally known as the "duckbill". New cross country bindings eliminate the flange entirely and use a steel bar embedded within the sole instead.
See also
Casing head
Closet flange
Victaulic
Swivel
References
Further reading
ASME B16.5: Standard Pipe Flanges up to and including 24 inches nominal
ASME B16.47: Standard Pipe Flanges above 24 inches
ASME Section II (Materials), Part A – Ferrous Material Specifications
ASME B16.47 Standard Pipe Flanges Yaang Pipe Industry
ANSI Flange Torque Lookup Tool
Piping
Plumbing
Mechanical engineering
Structural engineering
Train wheels | Flange | Physics,Chemistry,Engineering | 3,076 |
34,606,312 | https://en.wikipedia.org/wiki/Schaffer%E2%80%93Vega%20diversity%20system | The Schaffer–Vega diversity system (SVDS) was a wireless guitar system developed in 1975–76, engineered and prototyped by Ken Schaffer in New York City, and manufactured by the Vega Corporation, El Monte, California. A handheld microphone version was introduced in 1977.
The system was the first cordless system to be adopted by major rock acts because it solved technical problems common to earlier wireless systems. The reliable sound and freedom of movement it provided paved the way for bands to tour with large multi-level stages in arenas. Schaffer-Vegas were used in the late 1970s and early 1980s by many rock bands such as Pink Floyd (namely guitarist David Gilmour), the Rolling Stones, AC/DC and Kiss.
Background
Traveling with the Rolling Stones on the Tour of The Americas '75, New York-based engineer and radio aficionado Ken Schaffer witnessed the limitations of then-existing wireless systems and sought to develop a better system. The Schaffer-Vega Diversity System (SVDS) combined several new technologies to present a wireless system that was largely immune to the frequent signal fades, interfering signals and limited dynamic range of previous wireless systems. Schaffer gave precedence to developing the first system for wireless guitar (1976) and then the wireless microphone (1977).
After prototyping the wireless system, Schaffer arranged its manufacture by the Vega Corporation, based in El Monte, California. The first bands to use Schaffer-Vega Diversity System were Kiss and Electric Light Orchestra. Though wireless systems afford great mobility on stage, Kiss switched to a wireless system for safety reasons: lead guitarist Ace Frehley had been knocked unconscious by a near-fatal shock traced to a ground fault between his wired guitar connection and a metal staging element. Going wireless with all guitars and microphones eliminated this hazard.
Technical highlights
The Schaffer–Vega diversity system used a space diversity method consisting of two independent VHF receivers fed by antennas placed at least one wavelength apart. Use of two full independent receivers, rather than two parallel antennas, made the Schaffer-Vega the first "True Diversity" system. The diversity technique prevented signal degradation due to multi-path cancellation. In the Schaffer-Vega system, a comparator monitored the instantaneous RF signal strength delivered by each antenna to its dedicated receiver, that switched to the other receiver when the currently selected receiver's signal strength fell below a quieting threshold.
The system achieved high interference rejection by using four helical resonator filters between the antenna and preamplifier stage of each receiver. This made it possible to use the systems on unused VHF television broadcast frequencies and protected the receivers from even strong spurious local signals (such as nearby police calls, taxi dispatch, etc.). Limited by the US FCC to 50 mW output, the Schaffer-Vega Diversity System maintained reliable transmission for up to 100 meters in a line of sight from transmitter to receiver.
In the United States, the FCC and corresponding agencies in most ITU countries, regulations that limit the transmitter's FM frequency deviation also limited the theoretical signal-to-noise ratios and dynamic ranges of wireless systems to approximately 70 dB. The Schaffer-Vega Diversity System also used companding. By compressing signal amplitude 2:1 in the transmitter and then expanding it in the receiver, it was possible for the system to deliver a signal-to-noise ratio and dynamic range of 100 dB.
Use in the recording studio
Although Schaffer's design objective was to create a wireless system that sounded transparent—as close as possible to the wired version—artists, such as Rick Derringer, Eddie Van Halen and Angus Young of AC/DC, chose to use their wireless units in the recording studio. The slight coloration added by the Schaffer-Vega was considered part of the desired guitar tone. In 2015, the audio section of the SVDS was put into production and brought to market as a stand-alone effect by Filippo "SoloDallas" Olivieri and selected for inclusion in Guitar Player Magazine's 2015 Hall of Fame.
Cessation of production
Production ended in 1981, when Schaffer changed his focus to communications satellites. By the time Schaffer moved on, numerous competing systems had become staples in the market.
References
Guitar parts and accessories
Microphones
Wireless transmitters
Audio electronics | Schaffer–Vega diversity system | Engineering | 885 |
3,405,565 | https://en.wikipedia.org/wiki/Form-based%20code | A Form-Based Code (FBC) is a means of regulating land development to achieve a specific urban form. Form-Based Codes foster predictable built results and a high-quality public realm by using physical form (rather than separation of uses) as the organizing principle, with less focus on land use, through municipal regulations. An FBC is a regulation, not a mere guideline, adopted into city, town, or county law and offers a powerful alternative to conventional zoning regulation.
Form-Based Codes are a new response to the modern challenges of urban sprawl, deterioration of historic neighborhoods, and neglect of pedestrian safety in new development. Tradition has declined as a guide to development patterns, and the widespread adoption by cities of single-use zoning regulations has discouraged compact, walkable urbanism. Form-Based Codes are a tool to address these deficiencies, and to provide local governments the regulatory means to achieve development objectives with greater certainty.
Scope
Form-Based Codes address the relationship between building facades and the public realm, the form and mass of buildings in relation to one another, and the scale and types of streets and blocks. The regulations and standards in Form-Based Codes, presented in both diagrams and words, are keyed to a regulating plan that designates the appropriate form and scale (and therefore, character) of development rather than only distinctions in land-use types. This is in contrast to conventional zoning's focus on the micromanagement and segregation of land uses, and the control of development intensity through abstract and uncoordinated parameters (e.g., floor area ratios, dwelling units per acre, setbacks, parking ratios) to the neglect of an integrated built form. Not to be confused with design guidelines or general statements of policy, form-based codes are regulatory, not advisory.
Form-Based Codes are drafted to achieve a community vision based on time-tested forms of urbanism. Ultimately, a Form-Based Code is a tool; the quality of development outcomes is dependent on the quality and objectives of the community plan that a code implements.
History
Form-Based Codes are part of a long history of shaping the built landscape. Such efforts go back to the urban designs of Hippodamus of Miletus, the planning of cities in ancient China, and Roman town planning. The Laws of the Indies, promulgated by the Spanish Crown starting in the 16th century, established some basic urban form requirements for colonial towns in the Americas. William Penn when planning Philadelphia in the 17th century did not shy from precise urban form requirements when he said, "Let every house be in a line, or upon a line, as much as may be."
During the 18th century, Baroque urban design commonly brought buildings to the fronts of their lots with common facade treatments. Baron Haussmann, appointed by Napoleon III to oversee the redevelopment of Paris in the 19th century, stipulated precise ratios of building heights to street widths; disposition and sizes of windows and doors on building facades; consistent planting of street trees; and standardization of material colors to bring unity and harmony to the public environment.
Emergence
Regulating urban form is a challenge in modern democracies. Design guidelines adopted by municipalities, without legal enforceability, often invite capricious observance, thus failing to produce the comprehensive changes required to produce satisfying public places. When public planning exercises fail to produce predictable results, citizens often rebel against any development. In addition, from early in the twentieth century to the present, attempts at regulating the built landscape have usually been done for reasons that neglect community form, that are more concerned with the uses of property and impacts of scale than the form that development takes. And a planning profession that in recent decades has focused on policy, neglecting design, encouraged an abstract intellectual response to problems that are largely physical in nature.
The development of modern Form-Based Codes was started by architects, urban designers, and physical planners frustrated by the ineffectiveness of past criticisms of sprawl development and the failure of critics to propose realistic alternatives. These professionals, used to thinking physically about community problems, began the search for systematic physical solutions in the 1970s. Architect Christopher Alexander published A Pattern Language in 1977, a compendium of physical rules for designing humane buildings and places. Ian McHarg developed systematic mapping tools to encourage deliberate development patterns sensitive to local environmental conditions. Traditional Neighborhood Development ordinances were drafted beginning in the early 1990s as sets of development regulations to promote traditional neighborhood forms in new development projects. TND ordinances were typically adopted as an optional regulatory procedure that developers could request in place of conventional zoning. But their design regulations were not mapped to parcels or streets in advance, so lacked predictability of outcomes; TND ordinances proved to be an instructive effort, but showed few results.
Meanwhile, the accelerating scale of worldwide urban growth and the rapid expansion of the extent of cities heightened the need for regulatory tools better equipped to deal with such growth. The first serious attempt at creating a modern form-based code was done in 1982 to guide the development of the Florida resort town of Seaside by the husband and wife design team of Andres Duany and Elizabeth Plater-Zyberk. Realizing that designing an entire town would be an overwhelming task and would in the end lack the visual serendipity that only comes from myriad creative minds at work, they created a design code that established basic physical standards mapped to parcels, and then invited developers and architects to put their own distinctive stamp on their projects—but operating within those standards. The Seaside Code proved very successful; the resulting development of the town of Seaside is widely recognized as one of the most important and appealing planning efforts of the post-World War II era.
Duany/Plater-Zyberk's codes and the work of subsequent form-based code practitioners are not top-down mandates from imperial designers as in the baroque era or the wishful thinking of design guidelines that lack enforceability, but are instead legal regulations adopted by units of local government. As regulations they possess police power; violators of the regulations can be cited, and their invocation or retraction must go through a legislative process. As such, the community plays a more forceful role in shaping its physical future.
Recent developments
Although the Seaside code was commissioned by a private developer, most current codes are commissioned by counties and municipalities. Since Seaside, the scale of Form-Based Coding projects has grown. Form-Based Coding can be applied at many scales, from a two-block main street to a county-wide region. An early Form-Based Code was adopted for downtown West Palm Beach in 1995. A significant code for a major urban arterial, the Columbia Pike in Arlington County, Virginia, was adopted in 2003 (Ferrell Madden Associates). A regional FBC was adopted in 2006 by St. Lucie County, Florida (Spikowski Associates, Dover-Kohl Partners). Duany/Plater-Zyberk has drafted a model FBC that is also a transect-based code that can be calibrated for local needs—the SMARTCODE. Its first attempted customization was done for Vicksburg, Mississippi in 2001 (Mouzon & Greene). The lessons learned there led to the first California adoption of a citywide Form-Based Code for the City of Sonoma in March 2003 (Crawford Multari & Clark Associates, Moule & Polyzoides), followed on June 16, 2003, by the first SmartCode adopted in the U.S., for central Petaluma, California (Fisher and Hall Urban Design, Crawford Multari & Clark Associates). SmartCodes are now being calibrated for Miami, Florida and Hurricane Katrina ravaged communities in Mississippi and Louisiana, along with cities as diverse as Taos, NM, Michigan City, IN, Jamestown, RI, Lawrence, KS, New Castle, DE, and Bran, Romania. Planetary climate change that must be mitigated by changes in the human environment will no doubt be an inducement to form-based and transect-based coding in the future.
The Cincinnati Form-Based Code adopted in 2013 is designed to be applied citywide in an incremental way, neighborhood by neighborhood. The code establishes transect zones and specifies standards for transects, building types, frontage types, walkable neighborhoods, and thoroughfares that can be adapted to each neighborhood.
Beaufort County, South Carolina adopted one of the first multijurisdictional Form-Based Codes at the end of 2014: In 2010, the County, the City of Beaufort and the City of Port Royal came together to hire Opticos Design, Inc. in Berkeley, California to draft the code.
The non-profit Form-Based Codes Institute was created in 2004 to establish standards and best practices for form-based codes. In Spring 2014, a new graduate-level studio dedicated to Form-Based Coding was launched at California State Polytechnic University, entitled "Form-Based Codes in the Context of Integrated Urbanism".
See also
Zoning in the United States
Development control in the United Kingdom
Statutory planning
References
External links
Form-Based Codes Institute
Form-Based Codes: A Guide for Planners, Urban Designers, Municipalities, and Developers
The Center for Applied Transect Studies
The Seaside Institute
Top 10 Misconceptions about form-based codes
AARP Livability Fact Sheet Series Form-Based Code
Form-Based Codes on Planetizen
Urban planning
Real property law
Zoning
New Urbanism | Form-based code | Engineering | 1,914 |
1,495,421 | https://en.wikipedia.org/wiki/Li%20%28unit%29 | Li or ri (, lǐ, or , shìlǐ), also known as the Chinese mile, is a traditional Chinese unit of distance. The li has varied considerably over time but was usually about one third of an English mile and now has a standardized length of a half-kilometer (). This is then divided into 1,500 chi or "Chinese feet".
The character 里 combines the characters for "field" (田, tián) and "earth" (土, tǔ), since it was considered to be about the length of a single village. As late as the 1940s, a "li" did not represent a fixed measure but could be longer or shorter depending on the effort required to cover the distance.
There is also another li (Traditional: 釐, Simplified: 厘, lí) that indicates a unit of length of a chi, but it is used much less commonly. This li is used in the People's Republic of China as the equivalent of the centi- prefix in metric units, thus limi (厘米, límǐ) for centimeter. The tonal difference makes it distinguishable to speakers of Chinese, but unless specifically noted otherwise, any reference to li will always refer to the longer traditional unit and not to either the shorter unit or the kilometer. This traditional unit, in terms of historical usage and distance proportion, can be considered the East Asian counterpart to the Western league unit. However, in English league commonly means "3 miles."
Changing values
Like most traditional Chinese measurements, the li was reputed to have been established by the Yellow Emperor at the founding of Chinese civilization around 2600 BC and standardized by Yu the Great of the Xia dynasty six hundred years later. Although the value varied from state to state during the Spring and Autumn period and Warring States periods, historians give a general value to the li of 405 meters prior to the Qin dynasty imposition of its standard in the 3rd century BC.
The basic Chinese traditional unit of distance was the chi. As its value changed over time, so did the lis. In addition, the number of chi per li was sometimes altered. To add further complexity, under the Qin dynasty, the li was set at 360 "paces" (, bù) but the number of chi per bu was subsequently changed from 6 to 5, shortening the li by . Thus, the Qin li of about 576 meters became (with other changes) the Han li, which was standardized at 415.8 meters.
The basic units of measurement remained stable over the Qin and Han periods. A bronze imperial standard measure, dated AD 9, had been preserved at the Imperial Palace in Beijing and came to light in 1924. This has allowed very accurate conversions to modern measurements, which has provided a new and extremely useful additional tool in the identification of place names and routes. These measurements have been confirmed in many ways including the discovery of a number of rulers found at archaeological sites, and careful measurements of distances between known points. The Han li was calculated by Dubs to be 415.8 metres and all indications are that this is a precise and reliable determination.
Under the Tang dynasty (AD 618–907), the li was approximately 323 meters.
In the late Manchu or Qing dynasty, the number of chi was increased from 1,500 per li to 1,800. This had a value of 2115 feet or 644.6 meters. In addition, the Qing added a longer unit called the tu, which was equal to 150 li (96.7 km).
These changes were undone by the Republic of China of Chiang Kai-shek, who adopted the metric system in 1928. The Republic of China (now also known as Taiwan) continues not to use the li at all but only the kilometer (Mandarin: , gōnglǐ, lit. "common li").
Under Mao Zedong, the People's Republic of China reinstituted the traditional units as a measure of anti-imperialism and cultural pride before officially adopting the metric system in 1984. A place was made within this for the traditional units, which were restandardized to metric values. A modern li is thus set at exactly half a kilometer (500 meters). However, unlike the jin which is still frequently preferred in daily use over the kilogram, the li is almost never used. Nonetheless, its appearance in many phrases and sayings means that "kilometer" must always be specified by saying gōnglǐ in full.
Cultural use
As one might expect for the equivalent of "mile", li appears in many Chinese sayings, locations, and proverbs as an indicator of great distances or the exotic:
One Chinese name for the Great Wall is the "Ten-Thousand-Li Long Wall" (). As in Greek, the number "ten thousand" is used figuratively in Chinese to mean any "immeasurable" value and this title has never provided a literal distance of 10,000 li (). The actual length of the modern Great Wall is around 42,000 li (), over 4 times the name's proverbially "immeasurable" length.
The Chinese proverb appearing in chapter 64 of the Tao Te Ching and commonly rendered as "A journey of a thousand miles begins with a single step" in fact refers to a thousand li: 千里之行，始於足下 (Qiānlǐzhīxíng, shǐyúzúxià).
The greatest horses of Chinese history including Red Hare and Hualiu (驊騮) are all referred to as "thousand-li horses" (, qiānlǐmǎ), since they could supposedly travel a thousand li () in a single day.
Li is sometimes used in location names, for example: Wulipu (Chinese: 五里铺镇), Hubei; Ankang Wulipu Airport (Chinese: 安康五里铺机场), Shaanxi. Sanlitun () is an area in Beijing.
Ri in Japan and Korea
The present day Korean ri (리, 里) and Japanese ri (里) are units of measurements that can be traced back to the Chinese li (里).
Although the Chinese unit was unofficially used in Japan since the Zhou dynasty, the countries officially adopted the measurement used by the Tang dynasty (618–907 AD). The ri of an earlier era in Japan was thus true to Chinese length, corresponding to six chō ( 500–600 m), but later evolved to denote the distance that a person carrying a load would aim to cover on mountain roads in one hour. Thus, there had been various ri of 36, 40, and 48 chō. In the Edo period, the Tokugawa shogunate defined 1 ri as 36 chō, allowing other variants, and the Japanese government adopted this last definition in 1891. The Japanese ri was, at that time, fixed to the metric system, ≈ 3.93 kilometres or about 2.44 miles. Therefore, one must be careful about the correspondence between chō and ri. See Kujūkuri Beach (99-ri beach) for a case.
In South Korea, the ri currently in use is a unit taken from the Han dynasty (206 BC–220 AD) li. It has a value of approximately 392.72 meters, or one tenth of the ri. The Aegukga, the national anthem of South Korea, and the Aegukka, the national anthem of North Korea, both mention 3,000 ri, which roughly corresponds to 1,200 km, the approximate longitudinal span of the Korean peninsula.
In North Korea the Chollima Movement, a campaign aimed at improving labour productivity along the lines of the earlier Soviet Stakhanovite movement, gets its name from the word "chollima" which refers to a thousand-ri horse (chŏn + ri + ma in North Korean Romanization).
See also
Chinese units of measurement
Japanese units of measurement
Korean units of measurement
League (unit) for a general discussion of league-style units
Qianlima for more on "thousand-li horse" including North Korean Chollima
Li (short)
References
Citations
Sources
Homer H. Dubs (1938): The History of the Former Han Dynasty by Pan Ku. Vol. One. Translator and editor: Homer H. Dubs. Baltimore. Waverly Press, Inc.
Homer H. Dubs (1955): The History of the Former Han Dynasty by Pan Ku. Vol. Three. Translator and editor: Homer H. Dubs. Ithaca, New York. Spoken Languages Services, Inc.
Hulsewé, A. F. P. (1961). "Han measures". A. F. P. Hulsewé, T'oung pao Archives, Vol. XLIX, Livre 3, pp. 206–207.
Needham, Joseph. (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 3, Civil Engineering and Nautics. Taipei: Caves Books Ltd.
History of science and technology in China
Units of length | Li (unit) | Mathematics | 1,836 |
41,592 | https://en.wikipedia.org/wiki/Provisioning%20%28technology%29 | In telecommunications, provisioning involves the process of preparing and equipping a network to allow it to provide new services to its users. In National Security/Emergency Preparedness telecommunications services, "provisioning" equates to "initiation" and includes altering the state of an existing priority service or capability.
The concept of network provisioning or service mediation, mostly used in the telecommunication industry, refers to the provisioning of the customer's services to the network elements, which are various equipment connected in that network communication system. Generally in telephony provisioning this is accomplished with network management database table mappings. It requires the existence of networking equipment and depends on network planning and design.
In a modern signal infrastructure employing information technology (IT) at all levels, there is no possible distinction between telecommunications services and "higher level" infrastructure. Accordingly, provisioning configures any required systems, provides users with access to data and technology resources, and refers to all enterprise-level information-resource management involved.
Organizationally, a CIO typically manages provisioning, necessarily involving human resources and IT departments cooperating to:
Give users access to data repositories or grant authorization to systems, network applications and databases based on a unique user identity.
Appropriate for their use hardware resources, such as computers, mobile phones and pagers.
As its core, the provisioning process monitors access rights and privileges to ensure the security of an enterprise's resources and user privacy. As a secondary responsibility, it ensures compliance and minimizes the vulnerability of systems to penetration and abuse. As a tertiary responsibility, it tries to reduce the amount of custom configuration using boot image control and other methods that radically reduce the number of different configurations involved.
Discussion of provisioning often appears in the context of virtualization, orchestration, utility computing, cloud computing, and open-configuration concepts and projects. For instance, the OASIS Provisioning Services Technical Committee (PSTC) defines an XML-based framework for exchanging user, resource, and service-provisioning information - SPML (Service Provisioning Markup Language) for "managing the provisioning and allocation of identity information and system resources within and between organizations".
Once provisioning has taken place, the process of SysOpping ensures the maintenance of services to the expected standards. Provisioning thus refers only to the setup or startup part of the service operation, and SysOpping to the ongoing support.
Network provisioning
One type of provisioning.
The services which are assigned to the customer in the customer relationship management (CRM) have to be provisioned on the network element which is enabling the service and allows the customer to actually use the service. The relation between a service configured in the CRM and a service on the network elements is not necessarily a one-to-one relationship; for example, services like Microsoft Media Server (mms://) can be enabled by more than one network element.
During the provisioning, the service mediation device translates the service and the corresponding parameters of the service to one or more services/parameters on the network elements involved. The algorithm used to translate a system service into network services is called provisioning logic.
Electronic invoice feeds from your carriers can be automatically downloaded directly into the core of the telecom expense management (TEM) software and it will immediately conduct an audit of each single line item charge all the way down to the User Support and Operations Center (USOC) level. The provisioning software will capture each circuit number provided by all of your carriers and if billing occurs outside of the contracted rate an exception rule will trigger a red flag and notify the pre-established staff member to review the billing error.
Server provisioning
Server provisioning is a set of actions to prepare a server with appropriate systems, data and software, and make it ready for network operation. Typical tasks when provisioning a server are: select a server from a pool of available servers, load the appropriate software (operating system, device drivers, middleware, and applications), appropriately customize and configure the system and the software to create or change a boot image for this server, and then change its parameters, such as IP address, IP Gateway to find associated network and storage resources (sometimes separated as resource provisioning) to audit the system. By auditing the system, you ensure OVAL compliance with limit vulnerability, ensure compliance, or install patches. After these actions, you restart the system and load the new software. This makes the system ready for operation. Typically an internet service provider (ISP) or network operations center will perform these tasks to a well-defined set of parameters, for example, a boot image that the organization has approved and which uses software it has license to. Many instances of such a boot image create a virtual dedicated host.
There are many software products available to automate the provisioning of servers, services and end-user devices. Examples: BMC Bladelogic Server Automation, HP Server Automation, IBM Tivoli Provisioning Manager, Redhat Kickstart, xCAT, HP Insight CMU, etc. Middleware and applications can be installed either when the operating system is installed or afterwards by using an Application Service Automation tool. Further questions are addressed in academia such as when provisioning should be issued and how many servers are needed in multi-tier, or multi-service applications.
In cloud computing, servers may be provisioned via a web user interface or an application programming interface (API). One of the unique things about cloud computing is how rapidly and easily this can be done. Monitoring software can be used to trigger automatic provisioning when existing resources become too heavily stressed.
In short, server provisioning configures servers based on resource requirements. The use of a hardware or software component (e.g. single/dual processor, RAM, HDD, RAID Controller, a number of LAN cards, applications, OS, etc.) depends on the functionality of the server, such as ISP, virtualization, NOS, or voice processing. Server redundancy depends on the availability of servers in the organization. Critical applications have less downtime when using cluster servers, RAID, or a mirroring system.
Service used by most larger-scale centers in part to avoid this. Additional resource provisioning may be done per service.
There are several software on the market for server provisioning such as Cobbler or HP Intelligent Provisioning.
User provisioning
User provisioning refers to the creation, maintenance and deactivation of user objects and user attributes, as they exist in one or more systems, directories or applications, in response to automated or interactive business processes. User provisioning software may include one or more of the following processes: change propagation, self-service workflow, consolidated user administration, delegated user administration, and federated change control. User objects may represent employees, contractors, vendors, partners, customers or other recipients of a service. Services may include electronic mail, inclusion in a published user directory, access to a database, access to a network or mainframe, etc. User provisioning is a type of identity management software, particularly useful within organizations, where users may be represented by multiple objects on multiple systems and multiple instances.
Self-service provisioning for cloud computing services
On-demand self-service is described by the National Institute of Standards and Technology (NIST) as an essential characteristic of cloud computing. The self-service nature of cloud computing lets end users obtain and remove cloud services―including applications, the infrastructure supporting the applications, and configuration― themselves without requiring the assistance of an IT staff member. The automatic self-servicing may target different application goals and constraints (e.g. deadlines and cost), as well as handling different application architectures (e.g., bags-of-tasks and workflows). Cloud users can obtain cloud services through a cloud service catalog or a self-service portal. Because business users can obtain and configure cloud services themselves, this means IT staff can be more productive and gives them more time to manage cloud infrastructures.
One downside of cloud service provisioning is that it is not instantaneous. A cloud virtual machine (VM) can be acquired at any time by the user, but it may take up to several minutes for the acquired VM to be ready to use. The VM startup time is dependent on factors, such as image size, VM type, data center location, and number of VMs. Cloud providers have different VM startup performance.
Mobile subscriber provisioning
Mobile subscriber provisioning refers to the setting up of new services, such as GPRS, MMS and Instant Messaging for an existing subscriber of a mobile phone network, and any gateways to standard Internet chat or mail services. The network operator typically sends these settings to the subscriber's handset using SMS text services or HTML, and less commonly WAP, depending on what the mobile operating systems can accept.
A general example of provisioning is with data services. A mobile user who is using his or her device for voice calling may wish to switch to data services in order to read emails or browse the Internet. The mobile device's services are "provisioned" and thus the user is able to stay connected through push emails and other features of smartphone services.
Device management systems can benefit end-users by incorporating plug-and-play data services, supporting whatever device the end-user is using.. Such a platform can automatically detect devices in the network, sending them settings for immediate and continued usability. The process is fully automated, keeping the history of used devices and sending settings only to subscriber devices which were not previously set. One method of managing mobile updates is to filter IMEI/IMSI pairs. Some operators report activity of 50 over-the-air settings update files per second.
Mobile content provisioning
This refers to delivering mobile content, such as mobile internet to a mobile phone, agnostic of the features of said device. These may include operating system type and versions, Java version, browser version, screen form factors, audio capabilities, language settings and many other characteristics. As of April 2006, an estimated 5,000 permutations were relevant. Mobile content provisioning facilitates a common user experience, though delivered on widely different handsets.
Mobile device provisioning
Provisioning devices involves delivering configuration data and policy settings to the mobile devices from a central point – Mobile device management system tools.
Internet access provisioning
When getting a customer online, the client system must be configured. Depending on the connection technology (e.g., DSL, Cable, Fibre), the client system configuration may include:
Modem configuration
Network authentication
Installing drivers
Setting up Wireless LAN
Securing operating system (primarily for Windows)
Configuring browser provider-specifics
E-mail provisioning (create mailboxes and aliases)
E-mail configuration in client systems
Installing additional support software or add-on packages
There are four approaches to provisioning internet access:
Hand out manuals: Manuals are a great help for experienced users, but inexperienced users will need to call the support hotline several times until all internet services are accessible. Every unintended change in the configuration, by user mistake or due to a software error, results in additional calls.
On-site setup by a technician: Sending a technician on-site is the most reliable approach from the provider's point of view, as the person ensures that the internet access is working, before leaving the customer's premises. This advantage comes at high costs – either for the provider or the customer, depending on the business model. Furthermore, it is inconvenient for customers, as they have to wait until they get an installation appointment and because they need to take a day off from work. For repairing an internet connection on-site or phone support will be needed again.
Server-side remote setup: Server-side modem configuration uses a protocol called TR-069. It is widely established and reliable. At the current stage it can only be used for modem configuration. Protocol extensions are discussed, but not yet practically implemented, particularly because most client devices and applications do not support them yet. All other steps of the provisioning process are left to the user, typically causing many rather long calls to the support hotline.
Installation CD: Also called a "client-side self-service installation" CD, it can cover the entire process from modem configuration to setting up client applications, including home networking devices. The software typically acts autonomously, i.e., it doesn't need an online connection and an expensive backend infrastructure. During such an installation process the software usually also install diagnosis and self-repair applications that support customers in case of problems, avoiding costly hotline calls. Such client-side applications also open completely new possibilities for marketing, cross- and upselling. Such solutions come from highly specialised companies or directly from the provider's development department.
References
Network access
Operating system technology | Provisioning (technology) | Engineering | 2,643 |
18,695,033 | https://en.wikipedia.org/wiki/Switzerland%20%28software%29 | Switzerland (named after the European country of the same name) is an open-source network monitoring utility developed and released by the Electronic Frontier Foundation (EFF). Its goal is to monitor network traffic between two systems running the program to see if the user's Internet service provider is violating network neutrality, like Comcast did in 2007 with the BitTorrent protocol.
Switzerland was featured in the Technology section of an issue of New Scientist in August 2008.
See also
HTTPS Everywhere – also made by the EFF
Privacy Badger – also made by the EFF
References
External links
Beta software
Free network-related software
Net neutrality
Electronic Frontier Foundation | Switzerland (software) | Engineering | 128 |
22,437,570 | https://en.wikipedia.org/wiki/Myrmecotrophy | Myrmecotrophy is the ability of plants to obtain nutrients from ants, a form of mutualism. Due to this behaviour the invasion of vegetation into harsh environments is promoted. The dead remains of insects thrown out by the ants are absorbed by the lenticular warts in myrmecophytes like Hydnophytum and Myrmecodia. Myrmecodia uses its lenticular warts to suck nutrients from the insects thrown out by the ants. The ants in turn benefit with a secure location to form their colony. The pitcher plant Nepenthes bicalcarata obtains an estimated 42% of its total foliar nitrogen from ant waste.
References
Myrmecology
Plant physiology | Myrmecotrophy | Biology | 148 |
30,831,536 | https://en.wikipedia.org/wiki/United%20States%20building%20energy%20codes | United States building energy codes are a subset of building codes that set minimum requirements for energy-efficient design and construction for new and renovated buildings. The intent of these energy codes is to moderate and reduce energy use and emissions throughout the lifetime of a building. Energy code provisions may include various aspects of building design and construction, such as: HVAC systems, building envelope, electrical, and lighting systems. There are building energy codes for both commercial and residential buildings. However, just as the United States does not have a national building code, it also does not have a national building energy code; rather, state, and local governments choose to adopt—and potentially revise—national model energy codes and standards. Consequently, building energy codes, and building codes in general, vary between states and jurisdictions.
Commercial and residential buildings, combined, account for 39% of total U.S. energy consumption and about 75% of total U.S. electricity use. As such, by setting the minimum energy-efficiency requirements for building design and construction, energy codes have the capacity to increase cost-savings, advance energy independence, reduce greenhouse gas emissions, and drive economic opportunity through technological innovations.
Overview of Building Codes in the United States
Building codes in the United States are a collection of regulations and laws adopted by state and local jurisdictions that set “minimum requirements for how structural systems, plumbing, heating, ventilation, and air conditioning (HVAC), natural gas systems and other aspects of residential and commercial buildings should be designed and constructed.” The building code in many jurisdictions will often refer to an overarching “building code," which contains a collection of subset regulations (also called codes), such as the: Electrical Code (referring to the electrical system), Building Code (referring to structure and design), Plumbing Code, Fire Code, Mechanical Code, and Energy Code. In general, these codes are interrelated and inform aspects of one another, for example, provisions in the Fire Code regarding commercial cooking appliances and exhaust hoods may refer to installation provisions of appliances in the Mechanical Code. Built on a long history of fire and natural disaster protection, the foundational purpose of building codes is to protect “the health, safety, and welfare of the public” as it pertains to the design and construction of buildings.
Codes vs. Standards vs. Model Codes
There is a distinction to be made between codes, standards, and model codes. Codes are mandatory, legally enforceable requirements adopted by state and local jurisdictions. Standards, founded on evidence-based technical information, are non-mandatory recommendations and guidelines for best practices regarding various aspects of building design and construction. Though jurisdictions can adopt standards directly in a building code, “standard committees generally write standards with the intent that they become a component of a model code.” A model building code is a building code that incorporates standards and is “developed and maintained by an organization independent of the jurisdiction responsible for enacting the building code.”
A model code does not carry the force of law, but is created to be adopted by a jurisdiction and is “written in a mandatory, enforceable language, [so] state and local jurisdictions can easily adopt the model.” If the model code is adopted—and likely revised to fit the context of a specific jurisdiction—then the model becomes a part of, or serves as the “model” for, the legally enforceable building code in state and local jurisdictions.
Model Building Codes in the United States
The most widely used model building codes in the United States are published by the International Code Council, or the ICC, colloquially known as the I-Codes. Fifty states and the District of Columbia have adopted the I-Codes at the state or jurisdictional level. The International Code Council (ICC) develops the codes and standards used to construct residential and commercial buildings, including homes and schools.
For commercial buildings, the central model code adopted as a base code in many jurisdictions is the International Building Code, developed by the ICC, and for residential buildings, the predominant model code used is the International Residential Code (IRC), also developed by the ICC. Other model building codes, created by the ICC, and often adopted as a part of jurisdictional building codes, include the International Fire Code, International Energy Conservation Code, and International Mechanical code. The I-Codes are updated every three years.
Model building codes are applied differently between states and jurisdictions. This is by design, when model codes are adopted, the code provisions are dependent on regional climate and hazard risks, for example, “while California’s codes focus more on earthquakes, Florida’s include more measures addressing hurricanes.” Upon adoption, model codes are often amended and managed in accordance with jurisdictional needs, preferences, and currently existing legislation. This means that, with every three year update of the I-Codes, some model code provisions will not be included in certain jurisdictional building codes.
As the National Institute of Standards and Technology put it, “some states may limit or strike out new requirements they view as too costly, unnecessary or otherwise inappropriate for their constituents. Others may see value in the updates, sealing them into law or even strengthening them to protect their community.” For example, in 2009 the International Residential Code (IRC) was updated to include a provision requiring sprinklers in all new one-and two-family residences, and townhouses. While California and Pennsylvania adopted the new change, other states like New Hampshire delayed adoption of the code until 2012, and further, some states like Alaska, Texas, and Georgia opposed the addition of the provision to their building codes altogether.
Building Energy Codes: Development & Adoption
Model Energy Codes & Standards
According to the U.S. Department of Energy, “energy codes and standards set minimum efficiency requirements for new and renovated buildings, assuring reductions in energy use and emissions over the life of the building.” As with other building codes, model energy codes and standards are often written in a language such that they can be adopted—wholly, partially, or amended—into a jurisdiction’s legal building code.
The primary baseline national model energy codes are the International Energy Conservation Code (IECC), the ANSI/ASHRAE/IESNA Standard 90.1: Energy-Efficient Standard for Buildings Except Low-Rise Residential Buildings (ASHRAE 90.1), and ASHRAE Standard 90.2: Energy-Efficient Standard of New Low-Rise Residential Buildings. Two private organizations develop these model energy codes, the International Code Council (ICC) and the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).
The IECC has provisions that apply to both residential and commercial buildings, and, as stated in the above description, ASHRAE 90.1 refers to all buildings except low-rise residential, and ASHRAE 90.2 refers to residential buildings three stories or less.
In the development of model energy codes and standards, commercial and residential buildings are considered separate in order to allow for different provisions and parameters.
Commercial
Commercial buildings are defined as “all buildings other than low-rise residential buildings, including multi-family high-rise residential buildings over three stories." The model code, IECC, and the standard, ASHRAE 90.1, apply to commercial buildings. The IECC references several ASHRAE Standards, in particular, ASHRAE 90.1 for commercial building construction.
Being a part of the ICC’s collection of model codes, the IECC is revised annually and published in full-form every three years. Headed by an ICC committee, revisions and code changes can be proposed by any interested individual, business, or organization. The development and revision process include two public hearings to consider revisions and testimony. The process concludes with a consensus vote, by IECC members, on all the changes.
ASHRAE 90.1 follows a similar path of development and revision. Though ASHRAE 90.1 is revised and published every three years just like the IECC, people can submit interim revisions at any time within this period. ASHRAE has a standards committee that manages the process, and votes on the final versions of the energy code.
Provisions in the commercial sector of the model codes affect building design and construction factors such as: thermal envelope, water heating, HVAC, and lighting systems. In the 2021 IECC model code, for example, there are provisions that reference ASHRAE 90.1 concerning insulation R-values for opaque parts of the building envelope. As another example, there are provisions in the IECC concerning the length, flow-rate, and insulation of piping as it relates to hot-water heaters in commercial buildings.
Residential
Residential buildings are defined as “one- and two-family attached or detached dwellings, and multi-family buildings three or fewer stories above grade.” The model code, IECC, and standard, ASHRAE 90.2, apply to residential buildings.
Both the residential component of the IECC and ASHRAE 90.2 follow the same development and revision processes as described above in the commercial section, however, in the case of ASHRAE 90.2, the standards committee is maintained by a separate committee than the one that heads ASHRAE 90.1.
Provisions in these model codes concern many of the same aspects as those in the commercial sector, just at a different scope. In the 2021 IECC model code concerning residential energy efficiency, for example, there are provisions concerning different fenestration (window) U-Factors that are dependent on climate zone. Additionally, similar to the commercial sector, the residential provisions address hot-water circulation systems, exterior lighting systems, and insulation.
Prescriptive vs. Performance
Energy code provisions are usually designed with two different compliance path formats (i.e., the path needed to meet the requirements or intended result of the code): Prescriptive and Performance-based.
A prescriptive energy code delineates specific requirements or criteria for building components that must be fulfilled in order to be in compliance with the code. For example, “the allowable watts per square foot of lighting systems, and the minimum energy efficiencies required of mechanical systems.”
Performance-based codes are results-oriented, where compliance is predicated more on performing to a certain baseline of energy use. The performance path allows for some more flexibility, when compared to prescriptive codes. The performance path achieves this by creating space for building design-solutions that provide trade-offs between energy-intensive systems in order to meet both the energy performance goal and optimize cost-effective measures for a specific building.
Code Adoption
Model energy codes and standards can be adopted into legal building codes by jurisdictions around the United States. However, state and local jurisdictions will often carryout amendments, addenda, and provisions of their own to suit specific needs and preferences.
The adoption of energy codes typically follow two main avenues: legislation or regulatory action. In each case, the adoption process usually includes an advisory body, review and revision process, and public hearings. With the legislation route, rather than creating an entire energy model code wholesale, the state legislation will often reference an already existing model energy code and standard like the IECC. In this case, state legislation is adopting the model code directly. The regulation route uses legislation not to adopt the code directly, but instead to delegate a regulatory agency or authority to adopt, implement, and enforce the energy code.
As reported by Pacific Northwest National Laboratory, there is one other, more rare path to code adoption via local government: “if a state has limited authority to adopt an energy code (a ‘home rule’ state), units of local government have the option to assume that responsibility.” For example, in 2001, Chicago became the first jurisdiction in Illinois to adopt a building energy code, a modified version of IECC 2000.
The U.S. Department of Energy has a presence throughout the development and adoption of building energy codes and standards; the DOE participates in provisions, hearings, and suggests changes to model codes. Likewise, federal regulations impact the processes involved in the development and adoption of national model energy codes. For example, the Energy Conservation and Production Act (ECPA) requires the DOE “to provide technical assistance to states to support implementation of state residential and commercial building energy efficiency codes.” Indeed, the DOE’s Office of Energy Efficiency & Renewable Energy runs the Building Energy Codes Program (BECP) for this exact reason, in order “to support building energy code development, adoption, implementation, and enforcement processes.”
Compliance & Enforcement
Building energy code compliance is usually done at the local or municipal level by professionals trained to conduct field inspections and review construction plans. Compliance is where the standards and agreed-upon codes become a reality, without proper compliance and enforcement the goals of the code will likely not come to fruition. However, “compliance and enforcement of building energy codes is a key challenge, even in jurisdictions with advanced building code processes. Local governments are often the most critical actors in supporting effective compliance and building code enforcement.”
Compliance requires cooperation at multiple levels and in multiple ways: state and local government issuing proper permits and establishing dedicated departments, the thorough education of building officials on new code developments, and the responsibility of building design and construction professionals to comply with the energy code. As the energy code continues develop in the United States, this sentiment may become increasingly outdated, but in discussing compliance: “It is important to note that building officials and builders in some parts of the country see the energy code as fundamentally different from the historical ‘health, life, and safety’ codes that were created primarily to protect occupants from fire, flooding, and collapse. Energy codes are a more recent addition to the building codes family, with the first having been adopted in the late 1970s, while structural and fire codes have existed for hundreds of years/When resources are limited at local building departments, which is often the case, the energy code is likely to get less attention.”
Energy Code Impacts
Benefits and Future Considerations
Since buildings make-up such a large percentage of U.S. energy consumption, energy efficient building codes can have a large positive impact on cost-savings, energy independence, and ecological systems.
Additionally, the adoption of codes that increase energy performance can improve building habitability and comfort which has been linked to an increase in productivity. Building-focused energy conservation has the potential to greatly reduce global carbon emissions. A reduction in carbon emissions can reduce air pollutants, mitigate harmful effects of climate change, and drive positive impacts on overall wellbeing and health.
Barriers and Drawbacks
In certain circumstances, adopting the energy efficient technologies required to meet building energy codes may increase overall costs for a builder. The vast amount of buildings codes and standards that regulate building design and construction can be confusing for builders, lawmakers, and code developers alike. This is made more apparent when trying to chart a path toward a specific goal such as energy efficiency and emissions reduction. In turn, it can present a barrier to energy code adoption.
See Also
Energy conservation ("Buildings")
Green building
International Energy Conservation Code
Building code
International Building Code
Energy
Energy-efficient HVAC
References
Building codes
Standards of the United States
Sustainability | United States building energy codes | Engineering | 3,064 |
63,866 | https://en.wikipedia.org/wiki/Palermo%20Technical%20Impact%20Hazard%20Scale | The Palermo Technical Impact Hazard Scale is a logarithmic scale used by astronomers to rate the potential hazard of impact of a near-Earth object (NEO). It combines two types of data—probability of impact and estimated kinetic yield—into a single "hazard" value. A rating of 0 means the hazard is equivalent to the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact). A rating of +2 would indicate the hazard is 100 times as great as a random background event. Scale values less than −2 reflect events for which there are no likely consequences, while Palermo Scale values between −2 and 0 indicate situations that merit careful monitoring. A similar but less complex scale is the Torino Scale, which is used for simpler descriptions in the non-scientific media.
, no asteroid has a cumulative rating for impacts above 0, and only three asteroids have ratings between −2 and 0. Historically, three asteroids had ratings above 0 and half a dozen more above −1, but most were downrated since.
Scale
The scale compares the likelihood of the detected potential impact with the average risk posed by objects of the same size or larger over the years until the date of the potential impact. This average risk from random impacts is known as the background risk. The Palermo Scale value, P, is defined by the equation:
where
pi is the impact probability
T is the time interval over which pi is considered
fB is the background impact frequency
The background impact frequency is defined for this purpose as:
where the energy threshold E is measured in megatons, and yr is the unit of T divided by one year.
For instance, this formula implies that the expected value of the time from now until the next impact greater than 1 megatonne is 33 years, and that when it occurs, there is a 50% chance that it will be above 2.4 megatonnes. This formula is only valid over a certain range of E.
However, another paper published in 2002 – the same year as the paper on which the Palermo scale is based – found a power law with different constants:
This formula gives considerably lower rates for a given E. For instance, it gives the rate for bolides of 10 megatonnes or more (like the Tunguska explosion) as 1 per thousand years, rather than 1 per 210 years (or a 38% probability that it happens at least once in a century) as in the Palermo formula. However, the authors give a rather large uncertainty (once in 400 to 1800 years for 10 megatonnes), due in part to uncertainties in determining the energies of the atmospheric impacts that they used in their determination.
Asteroids with high ratings
In 2002 the near-Earth object reached a positive rating on the scale of 0.18, indicating a higher-than-background threat. The value was subsequently lowered after more measurements were taken. is no longer considered to pose any risk and was removed from the Sentry Risk Table on 1 August 2002.
In September 2002, the highest Palermo rating was that of asteroid (29075) 1950 DA, with a value of 0.17 for a possible collision in the year 2880. By March 2022, the rating had been reduced to −2.0. As of October 2024, it has a rating of −0.93.
For a brief period in late December 2004, with an observation arc of 190 days, asteroid (then known only by its provisional designation ) held the record for the highest Palermo scale value, with a value of 1.10 for a possible collision in the year 2029. The 1.10 value indicated that a collision with this object was considered to be almost 12.6 times as likely as a random background event: 1 in 37 instead of 1 in 472. With further observation through 2021 there is no risk from Apophis for the next 100+ years.
, three asteroids have a cumulative Palermo Scale value above −2: (-0.69), (29075) 1950 DA (−0.93) and 101955 Bennu (−1.40). Four have cumulative Palermo Scale values between −2 and −3: (-2.70), (−2.77), (−2.86) and (−2.97). Of the 27 that have a cumulative Palermo Scale value between −3 and −4, four were discovered in 2024: (−3.30), (−3.50), (−3.63) and (−3.76).
See also
Asteroid impact avoidance
Asteroid impact prediction
Earth-grazing fireball
Impact event
List of asteroid close approaches to Earth
List of Earth-crossing asteroids
Time-domain astronomy
References
Further reading
The primary reference for the Palermo Technical Scale is "Quantifying the risk posed by potential Earth impacts" by Chesley et al., Icarus 159, 423-432 (2002).
External links
Palermo Technical Impact Hazard Scale at the Sentry monitoring system by CNEOS at JPL from NASA
Alert measurement systems
Hazard scales
Planetary defense
Logarithmic scales of measurement | Palermo Technical Impact Hazard Scale | Physics,Mathematics,Technology | 1,049 |
56,897,306 | https://en.wikipedia.org/wiki/Windows%20Server%202019 | Windows Server 2019 is the twelfth major version of the Windows NT operating system produced by Microsoft to be released under the Windows Server brand name. It is the second version of the server operating system based on the Windows 10 platform, after Windows Server 2016. It was announced on March 20, 2018 for the first Windows Insider preview release, and was released internationally on October 2, 2018, the same release date of Windows 10 version 1809. It was succeeded by Windows Server 2022 on August 18, 2021.
Mainstream support for Windows Server 2019 ended on January 9, 2024, and extended support will end on January 9, 2029.
Development and release
Windows Server 2019 was announced on March 20, 2018, and the first Windows Insider preview version was released on the same day. It was released for general availability on October 2 of the same year.
On October 6, 2018, distribution of Windows 10 version 1809 (build 17763) was paused while Microsoft investigated an issue with user data being deleted during an in-place upgrade. It affected systems where a user profile folder (e.g. Documents, Music or Pictures) had been moved to another location, but data was left in the original location. As Windows Server 2019 is based on the Windows version 1809 codebase, it too was removed from distribution at the time, but was re-released on November 13, 2018. The software product life cycle for Server 2019 was reset in accordance with the new release date.
Editions
Windows Server 2019 consists of the following editions:
Windows Server 2019 Essentials - intended for companies up to and including 25 employees, memory-limited.
Windows Server 2019 Standard - intended for companies with more than 25 employees or more than 1 server to separate server roles.
Windows Server 2019 Datacenter - is mainly used for placing multiple virtual machines on a physical host.
Features
Windows Server 2019 has the following new features:
Container services:
Support for Kubernetes (stable; v1.14)
Support for Tigera Calico (an open-source networking and security solution for containers, virtual machines, and native host-based workloads)
Linux containers on Windows
Storage:
Storage Spaces Direct
Storage Migration Service
Storage Replica
System Insights
Security:
Shielded Virtual Machines
Improved Windows Defender Advanced Threat Protection (ATP)
Administration:
Windows Admin Center
SetupDiag (a diagnostic tool that can be used to obtain details about why an upgrade was unsuccessful)
OpenSSH included
Web browser
Microsoft Edge did not support Server 2019 at release. Microsoft considers Internet Explorer 11 a "compatibility layer," not a browser. Edge added support in January 2020, but Server 2019 does not install it by default. Microsoft encourages server and enterprise users to install Edge.
See also
Microsoft Servers
Comparison of Microsoft Windows versions
Microsoft Windows version history
Comparison of operating systems
List of operating systems
References
2019
X86-64 operating systems
2018 software
Server 2019 | Windows Server 2019 | Technology | 570 |
69,459,821 | https://en.wikipedia.org/wiki/Japanese%20Federation%20of%20Synthetic%20Chemistry%20Workers%27%20Unions | The Japanese Federation of Synthetic Chemistry Workers' Unions (, Gokaroren) was a trade union representing workers in the chemical industry in Japan.
The union was founded in 1950, with the merger of two unions representing ammonium sulfate and phosphate workers. The same year, it was a founding affiliate of the General Council of Trade Unions of Japan (Sohyo). From 1953 until 1957, it was chaired by Ōta Kaoru. By 1967, it had 121,324 members.
The union was affiliated with the Japanese Trade Union Confederation from the late 1980s, and by 1996, it had 91,242 members. The All Japan Chemistry Workers' Union split away in 1987, but merged with Goka Roren in 1998 to form the Japanese Federation of Chemistry Workers' Unions.
References
Chemical industry trade unions
Trade unions established in 1950
Trade unions disestablished in 1998
Trade unions in Japan | Japanese Federation of Synthetic Chemistry Workers' Unions | Chemistry | 180 |
47,577,681 | https://en.wikipedia.org/wiki/Be%20star | Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as classical Be stars, is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer emission lines.
Definition and classification
Many stars have B-type spectra and show hydrogen emission lines, including many supergiants, Herbig Ae/Be stars, mass-transferring binary systems, and B[e] stars. It is preferred to restrict usage of the term Be star to non-supergiant stars showing one or more Balmer series lines in emission. These are sometimes referred to as classical Be stars. The emission lines may be present only at certain times.
Although the Be type spectrum is most strongly produced in class B stars, it is also detected in O and A shell stars, and these are sometimes included under the "Be star" banner. Be stars are primarily considered to be main sequence stars, but a number of subgiants and giant stars are also included.
Discovery
The first star recognized as a Be star was Gamma Cassiopeiae, observed 1866 by Angelo Secchi, the first star ever observed with emission lines. Many other bright stars were found to show similar spectra, although many of these are no longer considered to be classical Be stars. The brightest is Achernar, although it was not recognised as a Be star until 1976.
Model
With the understanding of the processes of emission line formation in the early 20th century it became clear that these lines in Be stars must come from circumstellar material ejected from the star helped by the rapid rotation of the star. All the observational characteristics of Be stars can now be explained with a gaseous disk that is formed of material ejected from the star. The infrared excess and the polarization result from the scattering of stellar light in the disk, while the line emission is formed by re-processing stellar ultraviolet light in the gaseous disc.
Shell stars
Some Be stars exhibit spectral features that are interpreted as a detached "shell" of gas surrounding the star, or more accurately a disc or ring. These shell features are thought to be caused when the disc of gas that is present around many Be stars is aligned edge on to us so that it creates very narrow absorption lines in the spectrum.
Variability
Be stars are often visually and spectroscopically variable. Be stars can be classified as Gamma Cassiopeiae variables when a transient or variable disk is observed. Be stars that show variability without clear indication of the mechanism are listed simply as BE in the General Catalogue of Variable Stars. Some of these are thought to be pulsating stars and are sometimes called Lambda Eridani variables.
References
Further reading
External links
Philippe Stee's homepage: Hot and Active Stars Research
Article from Olivier Thizy: Be Stars
Star types
1866 in science | Be star | Astronomy | 582 |
30,845,073 | https://en.wikipedia.org/wiki/Cholesterol%20total%20synthesis | Cholesterol total synthesis in chemistry describes the total synthesis of the complex biomolecule cholesterol and is considered a great scientific achievement. The research group of Robert Robinson with John Cornforth (Oxford University) published their synthesis in 1951 and that of Robert Burns Woodward with Franz Sondheimer (Harvard University) in 1952. Both groups competed for the first publication since 1950 with Robinson having started in 1932 and Woodward in 1949. According to historian Greg Mulheirn the Robinson effort was hampered by his micromanagement style of leadership and the Woodward effort was greatly facilitated by his good relationships with chemical industry. Around 1949 steroids like cortisone were produced from natural resources but expensive. Chemical companies Merck & Co. and Monsanto saw commercial opportunities for steroid synthesis and not only funded Woodward but also provided him with large quantities of certain chemical intermediates from pilot plants. Hard work also helped the Woodward effort: one of the intermediate compounds was named Christmasterone as it was synthesized on Christmas Day 1950 by Sondheimer.
Other cholesterol schemes have also been developed: racemic cholesterol was synthesized in 1966 by W.S. Johnson, the enantiomer of natural cholesterol was reported in 1996 by Rychnovsky and Mickus, in 2002 by Jiang & Covey and again in 2008 by Rychnovsky and Belani.
The molecule
Cholesterol is a tetracyclic alcohol and a type of sterol. Added to the sterol frame with the alcohol group at position 3 are 2 methyl groups at carbon positions 10 and 13 and a 2-isooctyl group at position 17. The molecule is unsaturated at position 5,6 with an alkene group. The total number of stereocenters is 8. The unnatural cholesterol molecule that has also been synthesized is called ent-cholesterol.
Robinson synthesis
The Robinson synthesis is an example of a so-called relay synthesis. As many of the chemical intermediates (all steroids) were already known and available from natural resources all that was needed for a formal synthesis was proof that these intermediates could be linked to each other via chemical synthesis. Starting point for the Robinson synthesis was 1,6-dihydroxynaphthalene 1 that was converted in about 20 steps into the then already known androsterone 4. Ruzicka had already demonstrated in 1938 that androsterone could be converted into androstenedione 5 and Robinson demonstrated its conversion to dehydroepiandrosterone 6 (note the epimerized hydroxyl group) also already a known compound. Conversion of 6 to pregnenolone 7 and then to allopregnanolone 8 allowed the addition of the tail group as the acetate in 9 and then conversion to cholestanol 10.
The conversion of cholestanol to cholesterol was already demonstrated by oxidation of the ketone, bromination to the bromoketone and elimination to the enone.
The conversion of cholestenone into cholesterol by the method of Dauben and Eastham (1950) consisted of reduction of the enol acetate (lithium aluminium hydride) and fractionation with digitonin for the isolation of the correct isomer.
Woodward synthesis
Starting point for the Woodward synthesis was the hydroquinone 1 that was converted to cis-bicycle 2 in a Diels-Alder reaction with butadiene. Conversion to the desired trans isomer 5 was accomplished by synthesis of the sodium enolate salt 4 (benzene, sodium hydride) followed by acidification. Reduction (lithium aluminium hydride) then gave diol 6, a dehydration (HCl/water) gave ketol 7, deoxygenation of its acetate by elemental zinc gave enone 8, formylation (ethyl formate) gave enol 9, Michael ethyl vinyl ketone addition (potassium t-butoxide/t-butanol) gave dione 11 which on reaction with KOH in dioxane gave tricycle 12 in an aldol condensation with elimination of the formyl group. In the next series of steps oxidation (osmium tetroxide) gave diol 13, protection (acetone/copper sulfate) gave acetonide 14, hydrogenation (palladium-strontium carbonate) gave 15, formylation (ethyl formate) gave enol 16 which protected as the enamine 17 (N-methylaniline/methanol) gave via the potassium anion 18, carboxylic acid 19 by reaction with cyanoethylene using triton B as the base.
Acid 19 was converted to lactone 20 (acetic anhydride, sodium acetate) and reaction with methylmagnesium chloride gave tetracyclic ketone 21. Treatment with periodic acid (dioxane) and piperidine acetate (benzene) gave aldehyde 24 through diol 22 (oxidation) and dialdehyde 23 (aldol condensation). Sodium dichromate oxidation gave carboxylic acid 25, Diazomethane treatment gave methyl ester 26 and sodium borohydride the allyl alcohol 27. Chiral resolution of this racemic compound with digitonin produced chiral 28 and on Oppenauer oxidation chiral 29. Hydrogenation (Adams' catalyst) gave alcohol 30, chromic acid oxidation gave ketone 31, sodium borohydride reduction stereoselectively gave alcohol 32, hydrolysis followed by acylation gave acetate 33, thionyl chloride treatment gave acyl chloride 34 and methyl cadmium the ketone 35.
In the final stages reaction of 35 with isohexylmagnesium bromide 36 gave diol 37, acetic acid treatment gave dehydration and then hydrogenation gave acetate 38. Hydrolysis of this ester gave cholestanol 39. The route from cholestanol to cholesterol was already known (see: Robinson synthesis).
External links
Woodward Cholesterol Synthesis @ SynArchive.com
References
Total synthesis | Cholesterol total synthesis | Chemistry | 1,272 |
38,323,559 | https://en.wikipedia.org/wiki/Order-8%20triangular%20tiling | In geometry, the order-8 triangular tiling is a regular tiling of the hyperbolic plane. It is represented by Schläfli symbol of {3,8}, having eight regular triangles around each vertex.
Uniform colorings
The half symmetry [1+,8,3] = [(4,3,3)] can be shown with alternating two colors of triangles:
Symmetry
From [(4,4,4)] symmetry, there are 15 small index subgroups (7 unique) by mirror removal and alternation operators. Mirrors can be removed if its branch orders are all even, and cuts neighboring branch orders in half. Removing two mirrors leaves a half-order gyration point where the removed mirrors met. In these images fundamental domains are alternately colored black and white, and mirrors exist on the boundaries between colors. Adding 3 bisecting mirrors across each fundamental domains creates 832 symmetry. The subgroup index-8 group, [(1+,4,1+,4,1+,4)] (222222) is the commutator subgroup of [(4,4,4)].
A larger subgroup is constructed [(4,4,4*)], index 8, as (2*2222) with gyration points removed, becomes (*22222222).
The symmetry can be doubled to 842 symmetry by adding a bisecting mirror across the fundamental domains. The symmetry can be extended by 6, as 832 symmetry, by 3 bisecting mirrors per domain.
Related polyhedra and tilings
From a Wythoff construction there are ten hyperbolic uniform tilings that can be based from the regular octagonal and order-8 triangular tilings.
Drawing the tiles colored as red on the original faces, yellow at the original vertices, and blue along the original edges, there are 10 forms.
It can also be generated from the (4 3 3) hyperbolic tilings:
See also
Order-8 tetrahedral honeycomb
Tilings of regular polygons
List of uniform planar tilings
List of regular polytopes
References
John H. Conway, Heidi Burgiel, Chaim Goodman-Strauss, The Symmetries of Things 2008, (Chapter 19, The Hyperbolic Archimedean Tessellations)
External links
Hyperbolic and Spherical Tiling Gallery
KaleidoTile 3: Educational software to create spherical, planar and hyperbolic tilings
Hyperbolic Planar Tessellations, Don Hatch
Hyperbolic tilings
Isogonal tilings
Isohedral tilings
Order-8 tilings
Regular tilings
Triangular tilings | Order-8 triangular tiling | Physics | 533 |
750,101 | https://en.wikipedia.org/wiki/Domain%20knowledge | Domain knowledge is knowledge of a specific discipline or field in contrast to general (or domain-independent) knowledge. The term is often used in reference to a more general discipline—for example, in describing a software engineer who has general knowledge of computer programming as well as domain knowledge about developing programs for a particular industry. People with domain knowledge are often regarded as specialists or experts in their field.
Knowledge capture
In software engineering, domain knowledge is knowledge about the environment in which the target system operates, for example, software agents. Domain knowledge usually must be learned from software users in the domain (as domain specialists/experts), rather than from software developers. It may include user workflows, data pipelines, business policies, configurations and constraints and is crucial in the development of a software application. Expert domain knowledge (frequently informal and ill-structured) is transformed in computer programs and active data, for example in a set of rules in knowledge bases, by knowledge engineers.
Communicating between end-users and software developers is often difficult. They must find a common language to communicate in. Developing enough shared vocabulary to communicate can often take a while.
The same knowledge can be included in different domain knowledge. Knowledge which may be applicable across a number of domains is called domain-independent knowledge, for example logic and mathematics. Operations on domain knowledge are performed by metaknowledge.
See also
Artificial intelligence
Domain (software engineering)
Domain engineering
Domain of discourse
Knowledge engineering
Subject-matter expert
Literature
Hjørland, B. & Albrechtsen, H. (1995). Toward A New Horizon in Information Science: Domain Analysis. Journal of the American Society for Information Science, 1995, 46(6), p. 400–425.
References
Knowledge engineering | Domain knowledge | Engineering | 351 |
1,032,215 | https://en.wikipedia.org/wiki/1089%20%28number%29 | 1089 is the integer after 1088 and before 1090. It is a square number (33 squared), a nonagonal number, a 32-gonal number, a 364-gonal number, and a centered octagonal number. 1089 is the first reverse-divisible number. The next is 2178 , and they are the only four-digit numbers that divide their reverse.
In magic
1089 is widely used in magic tricks because it can be "produced" from any two three-digit numbers. This allows it to be used as the basis for a Magician's Choice. For instance, one variation of the book test starts by having the spectator choose any two suitable numbers and then apply some basic maths to produce a single four-digit number. That number is always 1089. The spectator is then asked to turn to page 108 of a book and read the 9th word, which the magician has memorized. To the audience it looks like the number is random, but through manipulation, the result is always the same.
In base 10, the following steps always yield 1089:
Take any three-digit number where the first and last digits differ by more than 1.
Reverse the digits, and subtract the smaller from the larger one.
Add to this result the number produced by reversing its digits.
For example, if the spectator chooses 237 (or 732):
732 − 237 = 495
495 + 594 = 1089
as expected. On the other hand, if the spectator chooses 102 (or 201):
201 − 102 = 99
99 + 99 ≠ 1089
contradicting the rule. However, if we amend the third rule by reading 99 as a three-digit number 099 and take its reverse, we obtain:
201 − 102 = 099
099 + 990 = 1089
as expected.
Explanation
The spectator's 3-digit number can be written as 100 × A + 10 × B + 1 × C, and its reversal as 100 × C + 10 × B + 1 × A, where 1 ≤ A ≤ 9, 0 ≤ B ≤ 9 and 1 ≤ C ≤ 9. Their difference is 99 × (A − C) (For convenience, we assume A > C; if A < C, we first swap A and C.). If A − C is 0, the difference is 0, and we do not get a 3-digit number for the next step. If A − C is 1, the difference is 99. Using a leading 0 gives us a 3-digit number for the next step.
99 × (A − C) can also be written as 99 × [(A − C) − 1] + 99 = 100 × [(A − C) − 1] − 1 × [(A − C) − 1] + 90 + 9 = 100 × [(A − C) − 1] + 90 + 9 − (A − C) + 1 = 100 × [(A − C) − 1] + 10 × 9 + 1 × [10 − (A − C)]. (The first digit is (A − C) − 1, the second is 9 and the third is 10 − (A − C). As 2 ≤ A − C ≤ 9, both the first and third digits are guaranteed to be single digits.)
Its reversal is 100 × [10 − (A − C)] + 10 × 9 + 1 × [(A − C) − 1]. The sum is thus 101 × [(A − C) − 1] + 20 × 9 + 101 × [10 − (A − C)] = 101 × [(A − C) − 1 + 10 − (A − C)] + 20 × 9 = 101 × [−1 + 10] + 180 = 1089.
Other properties
Multiplying the number 1089 by the integers from 1 to 9 produces a pattern: multipliers adding up to 10 give products that are the digit reversals of each other:
1 × 1089 = 1089 ↔ 9 × 1089 = 9801
2 × 1089 = 2178 ↔ 8 × 1089 = 8712
3 × 1089 = 3267 ↔ 7 × 1089 = 7623
4 × 1089 = 4356 ↔ 6 × 1089 = 6534
5 × 1089 = 5445 ↔ 5 × 1089 = 5445
Also note the patterns within each column:
1 × 1089 = 1089
2 × 1089 = 2178
3 × 1089 = 3267
4 × 1089 = 4356
5 × 1089 = 5445
6 × 1089 = 6534
7 × 1089 = 7623
8 × 1089 = 8712
9 × 1089 = 9801
Numbers formed analogously in other bases, e.g. octal 1067 or hexadecimal 10EF, also have these properties.
Extragalactic astronomy
The numerical value of the cosmic microwave background radiation redshift is about ( corresponds to present time)
Other uses
In the Rich Text Format, the language code 1089 indicates the text is in Swahili.
References
Integers | 1089 (number) | Mathematics | 1,051 |
228,161 | https://en.wikipedia.org/wiki/Bernoulli%20polynomials | In mathematics, the Bernoulli polynomials, named after Jacob Bernoulli, combine the Bernoulli numbers and binomial coefficients. They are used for series expansion of functions, and with the Euler–MacLaurin formula.
These polynomials occur in the study of many special functions and, in particular, the Riemann zeta function and the Hurwitz zeta function. They are an Appell sequence (i.e. a Sheffer sequence for the ordinary derivative operator). For the Bernoulli polynomials, the number of crossings of the x-axis in the unit interval does not go up with the degree. In the limit of large degree, they approach, when appropriately scaled, the sine and cosine functions.
A similar set of polynomials, based on a generating function, is the family of Euler polynomials.
Representations
The Bernoulli polynomials Bn can be defined by a generating function. They also admit a variety of derived representations.
Generating functions
The generating function for the Bernoulli polynomials is
The generating function for the Euler polynomials is
Explicit formula
for , where are the Bernoulli numbers, and are the Euler numbers. It follows that and .
Representation by a differential operator
The Bernoulli polynomials are also given by
where is differentiation with respect to and the fraction is expanded as a formal power series. It follows that
cf. below. By the same token, the Euler polynomials are given by
Representation by an integral operator
The Bernoulli polynomials are also the unique polynomials determined by
The integral transform
on polynomials f, simply amounts to
This can be used to produce the inversion formulae below.
Integral Recurrence
In, it is deduced and proved that the Bernoulli polynomials can be obtained by the following integral recurrence
Another explicit formula
An explicit formula for the Bernoulli polynomials is given by
That is similar to the series expression for the Hurwitz zeta function in the complex plane. Indeed, there is the relationship
where is the Hurwitz zeta function. The latter generalizes the Bernoulli polynomials, allowing for non-integer values
The inner sum may be understood to be the th forward difference of that is,
where is the forward difference operator. Thus, one may write
This formula may be derived from an identity appearing above as follows. Since the forward difference operator equals
where is differentiation with respect to , we have, from the Mercator series,
As long as this operates on an th-degree polynomial such as one may let go from only up
An integral representation for the Bernoulli polynomials is given by the Nörlund–Rice integral, which follows from the expression as a finite difference.
An explicit formula for the Euler polynomials is given by
The above follows analogously, using the fact that
Sums of pth powers
Using either the above integral representation of or the identity , we have
(assuming 00 = 1).
Explicit expressions for low degrees
The first few Bernoulli polynomials are:
The first few Euler polynomials are:
Maximum and minimum
At higher the amount of variation in between and gets large. For instance, but showed that the maximum value () of between and obeys
unless is in which case
(where is the Riemann zeta function), while the minimum () obeys
unless in which case
These limits are quite close to the actual maximum and minimum, and Lehmer gives more accurate limits as well.
Differences and derivatives
The Bernoulli and Euler polynomials obey many relations from umbral calculus:
( is the forward difference operator). Also,
These polynomial sequences are Appell sequences:
Translations
These identities are also equivalent to saying that these polynomial sequences are Appell sequences. (Hermite polynomials are another example.)
Symmetries
Zhi-Wei Sun and Hao Pan established the following surprising symmetry relation: If and , then
where
Fourier series
The Fourier series of the Bernoulli polynomials is also a Dirichlet series, given by the expansion
Note the simple large n limit to suitably scaled trigonometric functions.
This is a special case of the analogous form for the Hurwitz zeta function
This expansion is valid only for when and is valid for when .
The Fourier series of the Euler polynomials may also be calculated. Defining the functions
for , the Euler polynomial has the Fourier series
Note that the and are odd and even, respectively:
They are related to the Legendre chi function as
Inversion
The Bernoulli and Euler polynomials may be inverted to express the monomial in terms of the polynomials.
Specifically, evidently from the above section on integral operators, it follows that
and
Relation to falling factorial
The Bernoulli polynomials may be expanded in terms of the falling factorial as
where and
denotes the Stirling number of the second kind. The above may be inverted to express the falling factorial in terms of the Bernoulli polynomials:
where
denotes the Stirling number of the first kind.
Multiplication theorems
The multiplication theorems were given by Joseph Ludwig Raabe in 1851:
For a natural number ,
Integrals
Two definite integrals relating the Bernoulli and Euler polynomials to the Bernoulli and Euler numbers are:
Another integral formula states
with the special case for
Periodic Bernoulli polynomials
A periodic Bernoulli polynomial is a Bernoulli polynomial evaluated at the fractional part of the argument . These functions are used to provide the remainder term in the Euler–Maclaurin formula relating sums to integrals. The first polynomial is a sawtooth function.
Strictly these functions are not polynomials at all and more properly should be termed the periodic Bernoulli functions, and is not even a function, being the derivative of a sawtooth and so a Dirac comb.
The following properties are of interest, valid for all :
is continuous for all
exists and is continuous for
for
See also
Bernoulli numbers
Bernoulli polynomials of the second kind
Stirling polynomial
Polynomials calculating sums of powers of arithmetic progressions
References
Milton Abramowitz and Irene A. Stegun, eds. Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, (1972) Dover, New York. (See Chapter 23)
(See chapter 12.11)
(Reviews relationship to the Hurwitz zeta function and Lerch transcendent.)
External links
A list of integral identities involving Bernoulli polynomials from NIST
Special functions
Number theory
Polynomials | Bernoulli polynomials | Mathematics | 1,277 |
19,215,703 | https://en.wikipedia.org/wiki/Yttrium%20nitride | Yttrium nitride, YN, is a nitride of yttrium.
Yttrium nitride is hard ceramic material similar to titanium nitride and zirconium nitride.
The nitrides of lanthanum, scandium, and yttrium show semiconducting properties and additionally the lattice structure of YN differs only by 8% from that of gallium nitride. This makes YN a possible buffer layer between a substrate and the GaN layer during GaN crystal growth.
References
Nitrides
Yttrium compounds
Rock salt crystal structure | Yttrium nitride | Chemistry | 123 |
53,249,961 | https://en.wikipedia.org/wiki/Fileless%20malware | Fileless malware is a variant of computer related malicious software that exists exclusively as a computer memory-based artifact i.e. in RAM. It does not write any part of its activity to the computer's hard drive, thus increasing its ability to evade antivirus software that incorporate file-based whitelisting, signature detection, hardware verification, pattern-analysis, time-stamping, etc., and leaving very little evidence that could be used by digital forensic investigators to identify illegitimate activity. Malware of this type is designed to work in memory, so its existence on the system lasts only until the system is rebooted.
Definition
Fileless malware is sometimes considered synonymous with in-memory malware as both perform their core functionalities without writing data to disk during the lifetime of their operation. This has led some commentators to claim that this variant strain is nothing new and simply a “redefinition of the well-known term, memory resident virus”, whose pedigree can be traced back to the 1980s with the birth of the Lehigh Virus that was developed by the originator of the term, Fred Cohen, and became influential with his paper on the topic.
This synonymy is however incorrect. Although the aforementioned behavioral execution environment is the same, in both cases i.e. both malware variants are executed in system memory, the crucial differentiation is the method of inception and prolongation. Most malware's infection vector involves some writing to the hard disk, in order for it to be executed, whose origin could take the form of an infected file attachment, external media device e.g. USB, peripheral, mobile phone etc., browser drive-by, side-channel etc.
Each of the aforementioned methods has to have contact with the host system's hard drive, in some form or another, meaning that even when employing the stealthiest anti-forensic methods, some form of the infected residue will be left on the host media.
Fileless malware on the other hand, from the point of inception until process termination (usually by way of a system reboot), aims never to have its contents written to disk. Its purpose is to reside in volatile system areas such as the system registry, in-memory processes and service areas.
Fileless malware commonly employs the Living off the Land (LotL) technique which refers to the use of pre-existing operating system binaries to perform tasks. The goal of this technique is to avoid unnecessarily dropping extra malware on the system to perform tasks that can be done using already existing resources, this aids in stealth, primarily because the pre-existing system binaries are commonly signed and trusted. An example is an attacker using PsExec to connect to a target system.
History
Fileless malware is an evolutionary strain of malicious software that has taken on a steady model of self-improvement/enhancement with a drive towards clearly defined focused attack scenarios, whose roots can be traced back to the terminate-and-stay-resident viral programs that, once they were launched, would reside in memory awaiting a system interrupt before gaining access to their control flow; examples of which were seen in viruses such as Frodo, The Dark Avenger, Number of the Beast.
These techniques evolved by way of temporary memory resident viruses and were seen in famous examples such as: Anthrax, Monxla and took on their truer fileless nature by way of in-memory injected network viruses/worms such as CodeRed and Slammer.
More modern evolutionary incarnations have been seen in viruses such as Stuxnet, Duqu, Poweliks, and Phasebot.
Recent developments
On February 8, 2017, Kaspersky Lab's Global Research & Analysis Team published a report titled: "Fileless attacks against enterprise networks" which implicates variants of this type of malware, and its latest incarnations, affecting 140 enterprise networks across the globe with banks, telecommunication companies and government organizations being the top targets.
The report details how a variant of fileless malware is using PowerShell scripts (located within the Microsoft Windows Registry system) to launch an attack against a target's machine leveraging a common attack framework called Metasploit with supporting attack tools such as Mimikatz, and leveraging standard Windows utilities such as ‘SC’ and ‘NETSH’ to assist with lateral movement.
The malware was only detected after a bank identified the Metasploit Meterpreter code running in physical memory on a central domain controller (DC).
Kaspersky Labs is not the only company to have identified such emerging trends, with most of the principal IT security anti-malware companies coming forward with similar findings: Symantec, Trend Micro, and Cybereason.
Digital forensics
The emergence of malware that operates in a fileless way presents a major problem to digital forensic investigators, whose reliance on being able to obtain digital artifacts from a crime scene is critical to ensuring chain of custody and producing evidence that is admissible in a court of law.
Many well-known digital forensic process models such as: Casey 2004, DFRWS 2001, NIJ 2004, Cohen 2009, all embed either an examination and/or analysis phase into their respective models, implying that evidence can be obtained/collected/preserved by some mechanism.
The difficulty becomes apparent when considering the standard operating procedures of digital investigators and how they should deal with a computer at a crime scene. Traditional methods direct the investigator to:
Do not, in any circumstances, switch the computer on
Make sure that the computer is switched off – some screen savers may give the appearance that the computer is switched off, but hard drive and monitor activity lights may indicate that the machine is switched on.
Remove the main power source battery from laptop computers.
Unplug the power and other devices from sockets on the computer itself
Fileless malware subverts the forensics models, as evidence acquisition can only take place against a memory image that has been obtained from a live running system that is to be investigated. This method, however, can itself compromise the acquired host's memory image and render legal admissibility questionable, or at the very least, instill enough reasonable doubt that the weight of the evidence presented may be drastically reduced, increasing the chances that Trojan horse or "some other dude done it" defenses may be used more effectively.
This renders this type of malware extremely attractive to adversaries wishing to secure a foothold in a network, perform difficult to trace lateral movement and do so in a quick and silent manner, when standard forensic investigatory practices are ill-prepared for the threat.
Notable attacks
Democratic National Committee cyber attacks
References
External links
Fileless malware: An evolving threat on the horizon
Say Hello to the Super-Stealthy Malware That’s Going Mainstream
Fileless Malware Takes 2016 By Storm
New Fileless Attack Using DNS Queries to Carry Out PowerShell Commands
Kovter becomes almost file-less, creates a new file type, and gets some new certificates
Computer forensics
Types of malware | Fileless malware | Engineering | 1,432 |
40,081,829 | https://en.wikipedia.org/wiki/Forensic%20statistics | Forensic statistics is the application of probability models and statistical techniques to scientific evidence, such as DNA evidence, and the law. In contrast to "everyday" statistics, to not engender bias or unduly draw conclusions, forensic statisticians report likelihoods as likelihood ratios (LR). This ratio of probabilities is then used by juries or judges to draw inferences or conclusions and decide legal matters. Jurors and judges rely on the strength of a DNA match, given by statistics, to make conclusions and determine guilt or innocence in legal matters.
In forensic science, the DNA evidence received for DNA profiling often contains a mixture of more than one person's DNA. DNA profiles are generated using a set procedure, however, the interpretation of a DNA profile becomes more complicated when the sample contains a mixture of DNA. Regardless of the number of contributors to the forensic sample, statistics and probabilities must be used to provide weight to the evidence and to describe what the results of the DNA evidence mean. In a single-source DNA profile, the statistic used is termed a random match probability (RMP). RMPs can also be used in certain situations to describe the results of the interpretation of a DNA mixture. Other statistical tools to describe DNA mixture profiles include likelihood ratios (LR) and combined probability of inclusion (CPI), also known as random man not excluded (RMNE).
Computer programs have been implemented with forensic DNA statistics for assessing the biological relationships between two or more people. Forensic science uses several approaches for DNA statistics with computer programs such as; match probability, exclusion probability, likelihood ratios, Bayesian approaches, and paternity and kinship testing.
Although the precise origin of this term remains unclear, it is apparent that the term was used in the 1980s and 1990s. Among the first forensic statistics conferences were two held in 1991 and 1993.
Random match probability
Random match possibilities (RMP) are used to estimate and express the rarity of a DNA profile. RMP can be defined as the probability that someone else in the population, chosen at random, would have the same genotype as the genotype of the contributor of the forensic evidence. RMP is calculated using the genotype frequencies at all the loci, or how common or rare the alleles of a genotype are. The genotype frequencies are multiplied across all loci, using the product rule, to calculate the RMP. This statistic gives weight to the evidence either for or against a particular suspect being a contributor to the DNA mixture sample.
RMP can only be used as a statistic to describe the DNA profile if it is from a single source or if the analyst is able to differentiate between the peaks on the electropherogram from the major and minor contributors of a mixture. Since the interpretation of DNA mixtures with more than two contributors is very difficult for analysts to do without computer software, RMP becomes difficult to calculate with a mixture of more than two people. If the major and minor contributor peaks can not be differentiated, there are other statistical methods that may be used.
If the DNA mixture contains a ratio of 4:1 of major to minor contributors, a modified random match probability (mRMP) may be able to be used as a statistical tool. For calculation of mRMP, the analyst must first deduce a major and minor contributor and their genotypes based on the peak heights given in the electropherogram. Computer software is often used in labs conducting DNA analysis in order to more accurately calculate the mRMP, since calculations for each of the most probable genotypes at each locus become tedious and inefficient for the analyst to do by hand.
Likelihood ratio
Sometimes it can be very difficult to determine the number of contributors in a DNA mixture. If the peaks are easily distinguished and the number of contributors is able to be determined, a likelihood ratio (LR) is used. LRs consider probabilities of events happening and rely on alternative pairs of hypotheses against which the evidence is assessed. These alternative pairs of hypotheses in forensic cases are the prosecutor's hypothesis and the defense hypothesis. In forensic biology cases, the hypotheses often state that the DNA came from a particular person or the DNA came from an unknown person. For example, the prosecution may hypothesize the DNA sample contains DNA from the victim and the suspect, while the defense may hypothesize that the sample contains DNA from the victim and an unknown person. The probabilities of the hypotheses are expressed as a ratio, with the prosecutor's hypothesis being in the numerator. The ratio then expresses the likelihood of both of the events in relation to each other. For the hypotheses where the mixture contains the suspect, the probability is 1, because one can distinguish the peaks and easily tell if the suspect can be excluded as a contributor at each locus based on his/her genotype. The probability of 1 assumes the suspect can not be excluded as a contributor. To determine the probabilities of the unknowns, all genotype possibilities must be determined for that locus.
Once the calculation of the likelihood ratio is made, the number calculated is turned into a statement to provide meaning to the statistic. For the previous example, if the LR calculated is x, then the LR means that the probability of the evidence is x times more likely if the sample contains the victim and the suspect than if it contains the victim and an unknown person. Likelihood ratio can also be defined as 1/RMP.
Combined Probability of Inclusion
Combined probability of inclusion (CPI) is a common statistic used when the analyst can not differentiate between the peaks from a major and minor contributor to a sample and the number of contributors can not be determined. CPI is also commonly known as random man not excluded (RMNE). This statistical calculation is done by adding all the frequencies of observed alleles and then squaring the value, which yields the value for probability of inclusion (PI). These values are then multiplied across all loci, resulting in the value for CPI. The value is squared so that all the possible combinations of genotypes are included in the calculation.
Once the calculation is done, a statement is made about the meaning of this calculation and what it means. For example, if the CPI calculated is 0.5, this means that the probability of someone chosen at random in the population not being excluded as a contributor to the DNA mixture is 0.5.
CPI relates to the evidence (the DNA mixture) and it is not dependent on the profile of any suspect. Therefore, CPI is a statistical tool that can be used to provide weight or strength to evidence when no other information about the crime is known. This is advantageous in situations where the genotypes in the DNA mixture can not be distinguished from one another. However, this statistic is not very discriminating and is not as powerful of a tool as likelihood ratios and random match probabilities can be when some information about the DNA mixture, such as the number of contributors or the genotypes of each contributor, can be distinguished. Another limitation to CPI is that it is not usable as a tool for the interpretation of a DNA mixture.
Blood stains
Blood stains are an important part of forensic statistics, as the analysis of blood drop collisions may help to picture the event that had previously gone on. Commonly blood stains are an elliptical shape, because of this blood stains are usually easy to determine the blood droplets angle through the formula “α = arcsin d/a”. In this formula 'a' and 'd' are simply estimations of the axis of the ellipse. From these calculations, a visualization of the event causing the stains is able to be drawn, and alongside further information such as the velocity of the entity that caused such stains.
Bibliography
Lucy, D. (2005.) Introduction to Statistics for Forensic Scientists, John Wiley and Sons.
References
Applied statistics
Statistics | Forensic statistics | Mathematics | 1,627 |
56,676,509 | https://en.wikipedia.org/wiki/Thermodesulfobium | Thermodesulfobium is a Gram-negative, strictly anaerobic, moderately thermophilic, non-spore-forming and non-motile genus of bacteria from the family of Thermodesulfobiaceae.
See also
List of bacteria genera
List of bacterial orders
References
Further reading
Thermoanaerobacterales
Bacteria genera
Thermophiles
Anaerobes | Thermodesulfobium | Biology | 82 |
36,388,800 | https://en.wikipedia.org/wiki/USA-90 | USA-90, also known as GPS IIA-10, GPS II-19 and GPS SVN-31, was an American navigation satellite which formed part of the Global Positioning System. It was the tenth of nineteen Block IIA GPS satellites to be launched.
Background
Global Positioning System (GPS) was developed by the U.S. Department of Defense to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces. Since its implementation, GPS has also become an integral asset in numerous civilian applications and industries around the globe, including recreational used (e.g., boating, aircraft, hiking), corporate vehicle fleet tracking, and surveying. GPS employs 24 spacecraft in 20,200 km circular orbits inclined at 55.0°. These vehicles are placed in 6 orbit planes with four operational satellites in each plane.
GPS Block 2 was the operational system, following the demonstration system composed of Block 1 (Navstar 1 - 11) spacecraft. These spacecraft were 3-axis stabilized, nadir pointing using reaction wheels. Dual solar arrays supplied 710 watts of power. They used S-band (SGLS) communications for control and telemetry and Ultra high frequency (UHF) cross-link between spacecraft. The payload consisted of two L-band navigation signals at 1575.42 MHz (L1) and 1227.60 MHz (L2). Each spacecraft carried 2 rubidium and 2 Cesium clocks and nuclear detonation detection sensors. Built by Rockwell Space Systems for the U.S. Air force, the spacecraft measured 5.3 m across with solar panels deployed and had a design life of 7.5 years.
Launch
USA-90 was launched at 03:09:00 UTC on 30 March 1993, atop a Delta II launch vehicle, flight number D219, flying in the 7925-9.5 configuration. The launch took place from Launch Complex 17A (LC-17A) at the Cape Canaveral Air Force Station (CCAFS), and placed USA-90 into a transfer orbit. The satellite raised itself into medium Earth orbit using a Star-37XFP apogee motor.
Mission
On 2 May 1993, USA-90 was in an orbit with a perigee of , an apogee of , a period of 717.96 minutes, and 54.9° of inclination to the equator. It broadcast PRN 31, and operated in slot 3 of plane C of the GPS constellation. The satellite had a mass of . It had a design life of 7.5 years, and ceased operations on 24 October 2005.
References
Spacecraft launched in 1993
GPS satellites
USA satellites | USA-90 | Technology | 543 |
40,927,829 | https://en.wikipedia.org/wiki/Microascus%20brevicaulis | Microascus brevicaulis is a microfungus in the Ascomycota. It is the teleomorph form of Scopulariopsis brevicaulis. Microascus brevicaulis occurs world-wide as a saprotroph in soil, a common agent of biodeterioration, an irregular plant pathogen, and an occasional agent of human nail infection.
Name
Most of the discussion of this fungus in the scientific and medical literature has referred to the fungus using the name of its asexual form, or anamorph, Scopulariopsis brevicaulis. However, a sexual form (teleomorph) named Microascus brevicaulis was recently described. Under the current revision of International Code of Nomenclature for Algae, Fungi, and Plants, as articulated in the Shenzhen Code 2018, it remains unclear which name this fungus will ultimately take. Until further clarification, Microascus brevicaulis is considered the most recent, accepted name.
Bartolomeo Gosio discovered in 1890 that under wet conditions M. brevicaulis produces significant amounts of trimethylarsine via biomethylation of inorganic pigments especially Paris green or Scheele's Green used in indoor wallpapers which is then released into the air.
Morphology
Microascus brevicaulis is a common mold. When cultured at a temperature of 25 °C on potato dextrose agar it forms white colonies which become powdery and/or granular as they mature. Under such conditions the fungus can grow rapidly, expanding as much as 4.5 - 5.5 cm within one week. The hyphae of M. brevicaulis are hyaline (transparent) and septate (separated into segments by cross-walls). The anamorph has conidia that are flattened on the base and tapered at the apex, resembling a boat keel in cross-section or a pontifical mitre. The conidia are produced in chains from cells known as annelides, phialide-like cells that elongate with each successive conidium produced. These, in turn, range from solitary to arranged in complex broom-like clusters on fertile hyphae known as conidiophores. The fungus is a typical perithecial member of Phylum Ascomycota, producing minute, enclosed fruiting bodies containing sexual spores (ascospores) in sacs known as asci. The ascospores of M. brevicaulis are kidney-shaped and reddish-brown in colour.
Ecology
This fungus usually occurs as a mold present in numerous different types of soil as well as various decaying types of organic matter. Microascus brevicaulis has a world-wide distribution, and occurs chiefly as a soil saprotroph. The species is also encountered with some frequency as a non-dermatophyte agent of nail infections (onychomycosis), particularly in toenails. Besides the typical soil life of a decomposer, this fungus is also known to live within the American dog tick, Dermacentor variabilis. This relationship seems to be highly adapted but not as a classic host-parasite interaction. Studies have shown M. brevicaulis inhabits its host as an endosymbiont, and may provides protection against the insect-pathogenic fungus, Metarhizium anisopliae.
Pathogenicity in humans
Microascus brevicaulis has typically been associated with infections located on the skin surface of patients. Though this fungus is responsible for causing several skin related diseases, it is not considered a habitual pathogen. It is however categorized as a dermatomycotic mold which is known to cause onychomycosis. This is the most prevalent disease affecting human nails but M. brevicaulis has been isolated from healthy nails as well as diseased ones, indicating that it could be a harmless contaminant in some situations but behave as an opportunistic pathogen in others. Microascus brevicaulis is also known to cause granulomatous skin infections in humans. Yet another dermatological disease which may be caused by M.. brevicaulis is skin infection on the sole of the foot. These infections appear as red bumps or (less commonly ridges) around the patients hands and feet. Usually, these infections cause no pain and do not last very long thus resolve without treatment. In some cases however, these types of infection may be persistent and cause great discomfort. Yet another dermatological disease which may be caused by M. brevicaulis is plantar infection. This consists of a (potentially thick) scaly plaque that accumulates on the feet. Despite the discomfort and pain which dermatological infections of this sort inflict upon patients, M. brevicaulis is considerably more dangerous (even fatal) in situations where it manages to bypass the skin and reach deep tissues. The danger arises because M. brevicaulis is a multi-drug resistant, opportunistic pathogen. In the past, these kinds of infections mostly occurred if an individual punctured their skin with a stick or experienced some similar form of trauma that could implant M. brevicaulis below the skin. However, in recent years there has been an increase in the previously rare number of cases of deep tissue infections resulting from M. brevicaulis. In contemporary cases where deep tissue invasion has occurred, the patients are almost always immunocompromised. It is believed that the increasing incidence of diseases like AIDS and diabetes coupled with medical practices like chemo-therapy and broad-spectrum antibiotic treatments are primarily responsible for creating a large number of individuals who are predisposed to potentially fatal infections of M. brevicaulis. Another more recent entry route for this fungus has been an increase in the number of elective surgeries which raise its exposure to internal environments. The occurrence of such infections is on the rise and includes several life-threatening conditions such as: the formation of fungus balls in preformed pulmonary cavities, keratitis, posttraumatic endophthalmitis, disseminated skin lesions in AIDS patients, granulomatous subcutaneous infections, invasive hyalohyphomycosis, pneumonia in leukemic patients, endocarditis related to valvuloplasty or prosthetic valves, and fatal disseminated infection after bone marrow transplantation. In other cases, M. brevicaulis has caused death in immunocompromised patients with hematological diseases.
References
External links
Index Fungorum
USDA ARS Fungal Database
Microascales
Fungal plant pathogens and diseases
Fungi described in 1886
Fungus species | Microascus brevicaulis | Biology | 1,397 |
20,935,882 | https://en.wikipedia.org/wiki/Barium%20borate | Barium borate is an inorganic compound, a borate of barium with a chemical formula BaB2O4 or Ba(BO2)2. It is available as a hydrate or dehydrated form, as white powder or colorless crystals. The crystals exist in the high-temperature α phase and low-temperature β phase, abbreviated as BBO; both phases are birefringent, and BBO is a common nonlinear optical material.
Barium borate was discovered and developed by Chen Chuangtian and others of the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences.
Properties
Barium borate exists in three major crystalline forms: alpha, beta, and gamma. The low-temperature beta phase converts into the alpha phase upon heating to 925 °C. β-Barium borate (BBO) differs from the α form by the positions of the barium ions within the crystal. Both phases are birefringent, however the α phase possesses centric symmetry and thus does not have the same nonlinear properties as the β phase.
Alpha barium borate, α-BaB2O4 is an optical material with a very wide optical transmission window from about 190 nm to 3500 nm. It has good mechanical properties and is a suitable material for high-power ultraviolet polarization optics. It can replace calcite, titanium dioxide or lithium niobate in Glan–Taylor prisms, Glan–Thompson prisms, walk-off beam splitters and other optical components. It has low hygroscopicity, and its Mohs hardness is 4.5. Its damage threshold is 1 GW/cm2 at 1064 nm and 500 MW/cm2 at 355 nm.
Beta barium borate, β-BaB2O4, is a nonlinear optical material transparent in the range ~190–3300 nm. It can be used for spontaneous parametric down-conversion. Its Mohs hardness is also 4.5. The material exhibits a melting temperature of 1268 K, with anisotropic thermal expansion coefficients: and α₃₃ = 36 × 10⁻⁶ K⁻¹.
Gamma barium borate, γ-BaB2O4, discovered recently, was produced by heating beta barium borate 900 °C under 3 GPa of pressure. It was found to have a monoclinic crystal structure.
Barium borate has strong negative uniaxial birefringence and can be phase-matched for type I (ooe) second-harmonic generation from 409.6 to 3500 nm. The temperature sensitivity of the indices of refraction is low, leading to an unusually large (55 °C) temperature phase-matching bandwidth.
Although the ambient-pressure α and β crystal phases contain only trigonal, sp2 hybridized, boron, BBO glass has around 40% of the boron on tetrahedral, sp3 hybridized, sites. In the liquid state the relative fractions of sp2 and sp3 boron are temperature-dependent, with the trigonal planar coordination favored at higher temperatures.
Synthesis
Barium borate can be prepared by reaction of an aqueous solution of boric acid with barium hydroxide. The prepared γ-barium borate contains water of crystallization that can not be completely removed by drying at 120 °C. Dehydrated γ-barium borate can be prepared by heating to 300–400 °C. Calcination at about 600–800 °C causes complete conversion to the β form. BBO prepared by this method does not contain trace amounts of BaB2O2
BBO crystals for nonlinear optics can be grown from fluxed melt of barium borate, sodium oxide and sodium chloride.
Thin films of barium borate can be prepared by MOCVD from barium(II) hydro-tri(1-pyrazolyl)borate. Different phases can be obtained depending on deposition temperatures. Thin films of beta-barium borate can be prepared by sol-gel synthesis.
Barium borate monohydrate is prepared from the solution of barium sulfide and sodium tetraborate. It is a white powder. It is used as an additive to e.g. paints as flame retardant, mold inhibitor, and corrosion inhibitor. It is also used as a white pigment.
Barium borate dihydrate is prepared from the solution of sodium metaborate and barium chloride at 90–95 °C. After cooling to room temperature, white powder is precipitated. Barium borate dihydrate loses water at above 140 °C. It is used as a flame retardant for paints, textiles, and paper.
Applications
BBO is a popular nonlinear optical crystal. Quantum linked photons are producible with beta barium borate. Barium borate is a bactericide and fungicide. It is added to paints, coatings, adhesives, plastics, and paper products.
Barium borate is resistant to ultraviolet radiation. It can act as UV stabilizer for polyvinyl chloride.
The solubility of barium borate is a disadvantage when used as a pigment. Silica-coated powders are available. The alkaline properties and the anodic passivation properties of the borate ion enhance the anticorrosion performance. Commonly available barium metaborate pigment comes in three grades; Grade I is a barium metaborate itself, grade II is compounded with 27% zinc oxide, and grade III is compounded with 18% of zinc oxide and 29% calcium sulfate. Barium borate shows synergistic performance with zinc borate.
Barium borate is used as a flux in some barium titanate and lead zirconate EIA Class 2 dielectric ceramic formulations for ceramic capacitors, in amount of about 2%. The barium-boron ratio is critical for flux performance; BaB2O2 content adversely affects the performance of the flux.
Barium borate-fly ash glass can be used as radiation shielding. Such glasses are superior in performance to concrete and to other barium borate glasses.
References
Barium compounds
Borates
Nonlinear optical materials
Flame retardants
Corrosion inhibitors
Disinfectants
Fungicides
Inorganic pigments | Barium borate | Chemistry,Biology | 1,307 |
54,074,336 | https://en.wikipedia.org/wiki/Ynone | In organic chemistry, an ynone is an organic compound containing a ketone () functional group and a triple bond. Many ynones are α,β-ynones, where the carbonyl and alkyne groups are conjugated. Capillin is a naturally occurring example. Some ynones are not conjugated.
Synthesis of α,β-ynones
One method for synthesizing ynones is the acyl substitution reaction of an alkynyldimethylaluminum with an acyl chloride. An alkynyldimethylaluminum compound is the reaction product of trimethylaluminum and a terminal alkyne.
An alternative is the direct coupling of an acyl chloride with a terminal alkyne, using a copper-based nanocatalyst:
Other methods utilize an oxidative cleavage of an aldehyde, followed by reaction with a hypervalent alkynyl iodide, using a gold catalyst.
An alternative but longer synthetic method involves the reaction of an alkynyllithium compound with an aldehyde. The reaction produces a secondary alcohol that then can be oxidized via the Swern oxidation.
Synthesis of β,γ- and γ,δ-ynones
Terminal alkynes add across α,β-unsaturated ketones in the presence of palladium catalysts. The reaction affords γ,δ-ynones. Terminal alkynes add across epoxides to given yneols, which can be oxidized to give β,γ-ynones.
Further reading
Bis-ynones can undergo an intramolecular cycloaddition to form furan derivatives.
See also
Diketone
References
External links
Functional groups
Ketones
Alkyne derivatives | Ynone | Chemistry | 372 |
2,534,393 | https://en.wikipedia.org/wiki/Sodium%20dithiophosphate | Sodium dithiophosphate is the salt with the formula Na3PS2O2. It is usually supplied as the hydrated solid or as an aqueous solution together with other thiophosphates such as sodium monothiophosphate and sodium trithiophosphate. It is a colorless compound, but commercial samples can appear dark owing to the presence of impurities. It is used to facilitate the isolation of molybdenum from its ores.
Preparation
The compound has been prepared in a multistep process starting with the base hydrolysis of phosphorus pentasulfide:
P2S5 + 6 NaOH → 2 Na3PO2S2 + H2S + 2 H2O
The salt is isolated as the hydrate Na3PO2S2.(H2O)11. It is prone to hydrolysis, especially when it is heated as an aqueous solutions:
Na3PO2S2 + 2 H2O → Na3PO3S + H2S
Its structure has been examined by X-ray crystallography.
Applications
This salt is used as a flotation agent in the purification of molybdenite (MoS2) from other components of the ores, where it is usually known as "Nokes reagent" (after Charles M. Nokes, who patented it in 1948). The salt is generated by the reaction of phosphorus pentasulfide with sodium hydroxide, often using impure reagents to obtain a mixture of the desired salt and related thiophosphates and oxidized species. Molybdenite particles, which are normally hydrophobic, become hydrophilic in the presence of this salt. In this context, the Nokes reagent is called a "depressant," because it suppresses the flotation tendency of the solids other than molybdenite.
See also
Diethyl dithiophosphoric acid
Zinc dithiophosphate
References
Phosphorothioates
Sulfides
Sodium compounds
Metallurgical processes | Sodium dithiophosphate | Chemistry,Materials_science | 432 |
37,025,918 | https://en.wikipedia.org/wiki/Psi%20Eridani | Psi Eridani, Latinized from ψ Eridani, is a star in the constellation Eridanus. With an apparent visual magnitude is 4.81, it can be seen with the naked eye on a clear, dark night. Based upon an annual parallax shift of 4.41 milliarcseconds, it is located roughly 740 light-years away from the Sun.
This is a B-type main-sequence star with a stellar classification of B3 V. However, Houk and Swift (1999) classed it as a more evolved subgiant star. It is about 32 million years old and has a projected rotational velocity of 52 km/s. The estimated mass is seven times that of the Sun, and it has around 4.5 times the Sun's radius. Psi Eridani shines with 2,878 times the solar luminosity from its outer atmosphere at an effective temperature of 18,700 K.
References
B-type main-sequence stars
Eridanus (constellation)
Eridani, Psi
Eridani, 65
032249
023364
01617
Durchmusterung objects | Psi Eridani | Astronomy | 235 |
11,436,449 | https://en.wikipedia.org/wiki/Cercospora%20capsici | Cercospora capsici is a species of fungus in the family Mycosphaerellaceae. It is a plant pathogen that causes leaf spot, known as frogeye spot, on peppers.
References
capsici
Fungal plant pathogens and diseases
Eudicot diseases
Fungi described in 1911
Fungus species | Cercospora capsici | Biology | 61 |
27,855,839 | https://en.wikipedia.org/wiki/Madhouse%20%28ride%29 | A Madhouse is a flat ride usually manufactured by Vekoma. A similar attraction under the name Mystery Swing is created by Mack Rides. The ride is designed to be an optical and physical illusion, consisting of several rows of seats attached to a swaying gondola within a rotating drum. The ride creates the impression that the rider is turning upside down, whereas it is actually the room that is moving around them.
The ride is a modern implementation of a haunted swing illusion.
Ride experience
Madhouses are often extensively themed during the ride sequence, and usually in the queue line. Several madhouses feature pre-shows explaining a story behind the ride. Once in the ride, lapbars are lowered onto the riders, before they gradually experience an odd sense of movement. This is achieved through two mechanisms: the separate floor can move in a controlled swing from side-to-side by up to 7.5/15 degrees in each direction, but the surroundings of the room can rotate through a full 360 degrees. The pivot mechanism for the floor is hidden by two large objects at the end of the room, which are themed to match the ride.
At this point, both the floor and the room are slowly moving in unison. As the ride continues, the floor starts a separate movement from the rotating drum which gradually gives the impression that the room is rotating backwards and forwards further each time. Vekoma offers theme parks the option of programming their own sequence of how the room and floor move. In many madhouses, the lighting subtly changes from moment to moment to add to the disorientation. Eventually, the drum mechanism turns through a full rotation and, by careful synchronisation with the sensation of the swinging floor mechanism, the riders are fooled into feeling as if they themselves are being repeatedly turned upside down.
List of Madhouses
Cancelled installations
References
External links
A video showing how a Madhouse works
Official trailer for Hex, a Vekoma Madhouse at Alton Towers
Review of the Haunting Mad House at Drayton Manor
Amusement rides
Dark rides
Vekoma | Madhouse (ride) | Physics,Technology | 416 |
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