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2,149,887 | https://en.wikipedia.org/wiki/Reductive%20amination | Reductive amination (also known as reductive alkylation) is a form of amination that converts a carbonyl group to an amine via an intermediate imine. The carbonyl group is most commonly a ketone or an aldehyde. It is a common method to make amines and is widely used in green chemistry since it can be done catalytically in one-pot under mild conditions. In biochemistry, dehydrogenase enzymes use reductive amination to produce the amino acid glutamate. Additionally, there is ongoing research on alternative synthesis mechanisms with various metal catalysts which allow the reaction to be less energy taxing, and require milder reaction conditions. Investigation into biocatalysts, such as imine reductases, have allowed for higher selectivity in the reduction of chiral amines which is an important factor in pharmaceutical synthesis.
Reaction process
Reductive amination occurs between a carbonyl such as an aldehyde or ketone and an amine in the presence of a reducing agent. The reaction conditions are neutral or weakly acidic.
Reaction Steps
The nucelophilic amine reacts at the carbon of the carbonyl group to form a hemiaminal species
reversible loss of one molecule of water from the hemiaminal species by alkylimino-de-oxo-bisubstitution to form the imine intermediate. The equilibrium between aldehyde/ketone and imine is shifted toward imine formation by dehydration.
The intermediate imine can be isolated or reacted in-situ with a suitable reducing agent (e.g., sodium borohydride) to produce the amine product. Intramolecular reductive amination can also occur to afford a cyclic amine product if the amine and carbonyl are on the same molecule of starting material.
There are two ways to conduct a reductive amination reaction: direct and indirect.
Direct Reductive Amination
In a direct reaction, the carbonyl and amine starting materials and the reducing agent are combined and the reductions are done sequentially. These are often one-pot reactions since the imine intermediate is not isolated before the final reduction to the product. Instead, as the reaction proceeds, the imine becomes favoured for reduction over the carbonyl starting material. The two most common methods for direct reductive amination are hydrogenation with catalytic platinum, palladium, or nickel catalysts and the use of hydride reducing agents like cyanoborohydride (NaBH3CN).
Indirect Reductive Amination
Indirect reductive amination, also called a stepwise reduction, isolates the imine intermediate. In a separate step, the isolated imine intermediate is reduced to form the amine product.
Designing a reductive amination reaction
There are many considerations to be made when designing a reductive amination reaction.
Chemoselectivity issues may arise since the carbonyl group can also be reduced.
The reaction between the carbonyl and amine are in equilibrium, favouring the carbonyl unless water is removed from the system.
reduction-sensitive intermediates may form in the reaction which can affect chemoselectivity.
The amine substrate, imine intermediate, or amine product might deactivate the catalyst.
Acyclic imines have E/Z isomers. This makes it difficult to create enantiopure chiral compounds through stereoselective reductions.
To solve the last issue, asymmetric reductive amination reactions can be used to synthesize an enantiopure product of chiral amines. In asymmetric reductive amination, a carbonyl that can be converted from achiral to chiral is used. The carbonyl undergoes condensation with an amine in the presence of H2 and a chiral catalyst to form the imine intermediate, which is then reduced to form the amine. However, this method is still limiting to synthesize primary amines which are non-selective and prone to overalkylation.
Common reducing agents
Palladium Hydride
Palladium hydride (H2/Pd) is a versatile reducing agent commonly used in reductive amination reactions. Its catalytic efficiency stems from the ability of palladium to adsorb hydrogen gas, forming active hydride species. These hydrides facilitate the reduction of imines or iminium ions—key intermediates in reductive amination—into secondary or tertiary amines. This reaction typically occurs under mild conditions with excellent selectivity, which often makes H2/Pd the first choice for synthesizing amines in pharmaceuticals and fine chemicals. Additionally, H2/Pd is compatible with a wide range of functional groups, further enhancing its utility in complex organic synthesis.
Sodium Borohydride
Sodium Borohydride (NaBH4) reduces both imines and carbonyl groups. However, it is not very selective and can reduce other reducible functional groups present in the reaction. To ensure that this does not occur, reagents with weak electrophilic carbonyl groups, poor nucleophilic amines and sterically hindered reactive centres should not be used, as these properties do not favour the reduction of the carbonyl to form an imine and increases the chance that other functional groups will be reduced instead.
Sodium Cyanoborohydride
Sodium cyanoborohydride (NaBH3CN) is soluble in hydroxylic solvents, stable in acidic solutions, and has different selectivities depending on the pH. At low pH values, it efficiently reduces aldehydes and ketones. As the pH increases, the reduction rate slows and instead, the imine intermediate becomes preferential for reduction. For this reason, NaBH3CN is an ideal reducing agent for one-pot direct reductive amination reactions that don't isolate the intermediate imine.
When used as a reducing agent, NaBH3CN can release toxic by-products like HCN and NaCN during work up.
Sodium Triacetoxyborohydride
Sodium triacetoxyborohydride (STAB, NaBH(OAc)3) is a common reducing agent for reductive aminations. STAB selectively reduces the imine intermediate formed through dehydration of the molecule. STAB is a weaker reductant than NaBH4, and can preferentially reduce the imine group in the presence of other reduction-sensitive functional groups. While STAB has also been reported as a selective reducing agent for aldehydes in the presence of keto groups, standard reductive amination reaction conditions greatly favour imine reduction to form an amine.
Variations and related reactions
The reductive amination reaction is related to the Eschweiler–Clarke reaction, in which amines are methylated to tertiary amines, the Leuckart–Wallach reaction, and other amine alkylation methods such as the Mannich reaction and Petasis reaction.
A classic named reaction is the Mignonac reaction (1921) involving reaction of a ketone with ammonia over a nickel catalyst. An example of this reaction is the synthesis of 1-phenylethylamine from acetophenone:
Additionally, many systems catalyze reductive aminations with hydrogenation catalysts. Generally, catalysis is preferred to stoichiometric reactions as they may improve reaction efficiency and atom economy, and produce less waste. These reactions can utilize homogeneous or heterogeneous catalyst systems. These systems provide alternative synthesis routes which are efficient, require fewer volatile reagents and are redox-economical. As well, this method can be used in the reduction of alcohols, along with aldehydes and ketones to form the amine product. One example of a heterogeneous catalytic system is the Ni-catalyzed reductive amination of alcohols. Nickel is commonly used as a catalyst for reductive amination because of its abundance and relatively good catalytic activity.
An example of a homogeneous catalytic system is the reductive amination of ketones done with an iridium catalyst. Homogenous Iridium (III) catalysts have been shown to be effective in the reductive amination of carboxylic acids, which in the past has been more difficult than aldehydes and ketones. Homogeneous catalysts are often favored because they are more environmentally and economically friendly compared to most heterogeneous systems.
In industry, tertiary amines such as triethylamine and diisopropylethylamine are formed directly from ketones with a gaseous mixture of ammonia and hydrogen and a suitable catalyst.
In green chemistry
Reductive amination is commonly used over other methods for introducing amines to alkyl substrates, such as SN2-type reactions with halides, since it can be done in mild conditions and has high selectivity for nitrogen-containing compounds. Reductive amination can occur sequentially in one-pot reactions, which eliminates the need for intermediate purifications and reduces waste. Some multistep synthetic pathways have been reduced to one step through one-pot reductive amination. This makes it a highly appealing method to produce amines in green chemistry.
Biochemistry
In biochemistry, dehydrogenase enzymes can catalyze the reductive amination of α-keto acids and ammonia to yield α-amino acids. Reductive amination is predominantly used for the synthesis of the amino acid glutamate starting from α-ketoglutarate, while biochemistry largely relies on transamination to introduce nitrogen in the other amino acids. The use of enzymes as a catalyst is advantageous because the enzyme active sites are often stereospecific and have the ability to selectively synthesize a certain enantiomer. This is useful in the pharmaceutical industry, particularly for drug-development, because enantiomer pairs can have different reactivities in the body. Additionally, enzyme biocatalysts are often quite selective in reactivity so they can be used in the presence of other functional groups, without the use of protecting groups. For instance a class of enzymes called imine reductases, IREDs, can be used to catalyze direct asymmetric reductive amination to form chiral amines.
In popular culture
In the critically acclaimed drama Breaking Bad, main character Walter White uses the reductive amination reaction to produce his high purity methamphetamine, relying on phenyl-2-propanone and methylamine.
See also
Forster–Decker method
Leuckart reaction
References
External links
Current methods for reductive amination
Industrial reductive amination at BASF
Organic redox reactions | Reductive amination | [
"Chemistry"
] | 2,236 | [
"Coupling reactions",
"Organic redox reactions",
"Organic reactions"
] |
2,149,972 | https://en.wikipedia.org/wiki/Convective%20inhibition | Convective inhibition (CIN or CINH) is a numerical measure in meteorology that indicates the amount of energy that will prevent an air parcel from rising from the surface to the level of free convection.
CIN is the amount of energy required to overcome the negatively buoyant energy the environment exerts on an air parcel. In most cases, when CIN exists, it covers a layer from the ground to the level of free convection (LFC). The negatively buoyant energy exerted on an air parcel is a result of the air parcel being cooler (denser) than the air which surrounds it, which causes the air parcel to accelerate downward. The layer of air dominated by CIN is warmer and more stable than the layers above or below it.
The situation in which convective inhibition is measured is when layers of warmer air are above a particular region of air. The effect of having warm air above a cooler air parcel is to prevent the cooler air parcel from rising into the atmosphere. This creates a stable region of air. Convective inhibition indicates the amount of energy that will be required to force the cooler packet of air to rise. This energy comes from fronts, heating, moistening, or mesoscale convergence boundaries such as outflow and sea breeze boundaries, or orographic lift.
Typically, an area with a high convection inhibition number is considered stable and has very little likelihood of developing a thunderstorm. Conceptually, it is the opposite of CAPE.
CIN hinders updrafts necessary to produce convective weather, such as thunderstorms. Although, when large amounts of CIN are reduced by heating and moistening during a convective storm, the storm will be more severe than in the case when no CIN was present.
CIN is strengthened by low altitude dry air advection and surface air cooling. Surface cooling causes a small capping inversion to form aloft allowing the air to become stable. Incoming weather fronts and short waves influence the strengthening or weakening of CIN.
CIN is calculated by measurements recorded electronically by a Rawinsonde (weather balloon) which carries devices which measure weather parameters, such as air temperature and pressure. A single value for CIN is calculated from one balloon ascent by use of the equation below. The z-bottom and z-top limits of integration in the equation represent the bottom and top altitudes (in meters) of a single CIN layer, is the virtual temperature of the specific parcel and is the virtual temperature of the environment. In many cases, the z-bottom value is the ground and the z-top value is the LFC. CIN is an energy per unit mass and the units of measurement are joules per kilogram (J/kg). CIN is expressed as a negative energy value. CIN values greater than 200 J/kg are sufficient to prevent convection in the atmosphere.
The CIN energy value is an important figure on a skew-T log-P diagram and is a helpful value in evaluating the severity of a convective event. On a skew-T log-P diagram, CIN is any area between the warmer environment virtual temperature profile and the cooler parcel virtual temperature profile.
CIN is effectively negative buoyancy, expressed B-; the opposite of convective available potential energy (CAPE), which is expressed as B+ or simply B. As with CAPE, CIN is usually expressed in J/kg but may also be expressed as m2/s2, as the values are equivalent. In fact, CIN is sometimes referred to as negative buoyant energy (NBE).
See also
Atmospheric thermodynamics
Convective instability
Equilibrium level
Thermodynamic diagrams
References
External links
CINH Help Page
Atmospheric thermodynamics
Meteorological quantities
Severe weather and convection | Convective inhibition | [
"Physics",
"Mathematics"
] | 783 | [
"Quantity",
"Physical quantities",
"Meteorological quantities"
] |
2,150,057 | https://en.wikipedia.org/wiki/Emergency%20Action%20Message | In the United States military's strategic nuclear weapon nuclear command and control (NC2) system, an Emergency Action Message (EAM) is a preformatted message that directs nuclear-capable forces to execute specific Major Attack Options (MAOs) or Limited Attack Options (LAOs) in a nuclear war. They are the military commands that the US military chain of command would use to launch a nuclear strike. Individual countries or specific regions may be included or withheld in the EAM, as specified in the Single Integrated Operational Plan (SIOP). The SIOP was updated annually until February 2003, when it was replaced by Operations Plan (OPLAN) 8044. Since July 2012, the US nuclear war plan has been OPLAN 8010-12, Strategic Deterrence and Force Employment.
Overview
EAMs use cryptographic protocols (including such methods as digital signatures) to authenticate the messages, thereby ensuring that they cannot be forged or altered.
In the United States, the EAM will be issued from the National Military Command Center (NMCC) at the Pentagon or, if it has been destroyed by an enemy first strike, by the Alternate National Military Command Center - Site R at Raven Rock, Pennsylvania or by the U.S. Air Force E-4B Nightwatch aircraft/U.S. Navy E-6A Mercury aircraft (TACAMO).
The messages are sent in digital format to nuclear-capable major commands. The messages are then relayed to aircraft that are on alert by the U.S. Strategic Command at Offutt Air Force Base in Omaha, Nebraska, via single-sideband modulation radio transmitters of the High Frequency Global Communications System (formerly known as the Global High Frequency System). The EAM is relayed to missile-firing nuclear submarines via special transmitters designed for communication with submarines. The transmitters include those designed to operate at Very Low Frequency (VLF). The submarines pick up the message via special antennas. Nuclear-capable forces will then be expected to carry out an EAM without fail. Crewed bombers may be recalled, but missiles fired from land-based silos or from submarines cannot be recalled.
Skyking messages
Skyking messages, also known as "Foxtrot Broadcasts", are also read on the same network as EAMs. These messages will interrupt an EAM if needed to be read. They contain a higher priority and time-sensitive code for orders that need immediate attention.
In popular culture
The EAM system was featured extensively and used as one of the primary plot devices in the feature film Crimson Tide.
The start of a Sky King headed EAM message is briefly heard on the cockpit radio when the bomber crew are scrambled in the feature film By Dawn's Early Light.
See also
Gold Codes
Nuclear football
Emergency Action Notification
References
Further reading
(FOIA Release, February 1986)
Nuclear warfare
United States nuclear command and control | Emergency Action Message | [
"Chemistry"
] | 585 | [
"Radioactivity",
"Nuclear warfare"
] |
2,150,099 | https://en.wikipedia.org/wiki/MUSASINO-1 | The MUSASINO-1 was one of the earliest electronic digital computers built in Japan. Construction started at the Electrical Communication Laboratories of NTT at Musashino, Tokyo in 1952 and was completed in July 1957. The computer was used until July 1962. Saburo Muroga, a University of Illinois visiting scholar and member of the ILLIAC I team, returned to Japan and oversaw the construction of MUSASINO-1.
Using 519 vacuum tubes and 5,400 parametrons, the MUSASINO-1 possessed a magnetic core memory, initially of 32 (later expanded to 256) words. A word was composed of 40 bits, and two instructions could be stored in a single word. Addition time was clocked at 1,350 microseconds, multiplication at 6,800 microseconds, and division time at 26.1 milliseconds.
The MUSASINO-1's instruction set was a superset of the ILLIAC I's instructions, so it could generally use the latter's software. However, many of the programs for the ILLIAC used some of the unused bits in the instructions to store data, and these would be interpreted as a different instructions by the MUSASINO-1 control circuitry.
See also
FUJIC
ILLIAC I
List of vacuum-tube computers
References
Raúl Rojas and Ulf Hashagen, ed. The First Computers: History and Architectures. 2000, MIT Press, .
In memory of Saburo Muroga, CS @ Illinois Alumni Magazine, Summer 2011
External links
Descriptions of the MUSASINO-1 and its immediate successors at the IPSJ Computer Museum
IAS architecture computers
40-bit computers
Vacuum tube computers
Magnetic logic computers | MUSASINO-1 | [
"Technology"
] | 349 | [
"Computing stubs",
"Computer hardware stubs"
] |
2,150,292 | https://en.wikipedia.org/wiki/Sergei%20Winogradsky | Sergei Nikolaevich Winogradsky (; ; , Kyiv – 24 February 1953, Brie-Comte-Robert), also published under the name Sergius Winogradsky, was a Ukrainian and Russian microbiologist, ecologist and soil scientist who pioneered the cycle-of-life concept. Winogradsky discovered the first known form of lithotrophy during his research with Beggiatoa in 1887. He reported that Beggiatoa oxidized hydrogen sulfide (H2S) as an energy source and formed intracellular sulfur droplets. This research provided the first example of lithotrophy, but not autotrophy. Born in the capital of present-day Ukraine, his legacy is also celebrated by this nation.
His research on nitrifying bacteria would report the first known form of chemoautotrophy, showing how a lithotroph fixes carbon dioxide (CO2) to make organic compounds.
He is best known in school science as the inventor of the Winogradsky column technique for the study of sediment microbes.
Biography
Winogradsky was born in Kyiv, Russian Empire to a family of wealthy lawyers. Among his paternal ancestors were Cossack atamans, and on the maternal side he was linked to the Skoropadsky family. In his youth Winogradsky was "strictly devoted to the Orthodox faith", though he later became irreligious.
After graduating from the 2nd Kiev Gymnasium in 1873, he began studying law, but he entered the Imperial Conservatoire of Music in Saint Petersburg in 1875 to study piano. However, after two years of music training, he entered the Saint Petersburg Imperial University in 1877 to study chemistry under Nikolai Menshutkin and botany under Andrei Famintsyn, receiving his degree in 1881 and staying on for a master's in botany, which he received in 1884. In 1885, he moved to the University of Straßburg to work under the renowned botanist Anton de Bary, subsequently becoming renowned for his work on sulfur bacteria.
In 1888, after de Bary's death, he relocated to Zürich, where he began investigation into the process of nitrification, identifying the genera Nitrosomonas and Nitrosococcus, which oxidizes ammonium to nitrite, and Nitrobacter, which oxidizes nitrite to nitrate.
He returned to St. Petersburg for the period 1891–1905, obtaining his doctoral degree in 1902 and from then on heading the division of general microbiology of the Institute of Experimental Medicine. During this period, he identified the obligate anaerobe Clostridium pasteurianum, which is capable of fixing atmospheric nitrogen. In St. Petersburg he trained Vasily Omelianski, who popularized Winogradskys concepts and methodology in the Soviet Union during the next decades.
In 1901, he was elected an honorary member of the Moscow Society of Naturalists and, in 1902, a corresponding member of the French Academy of Sciences. In 1905, due to ill health, the scientist left the institute and moved from St. Petersburg to the town of Gorodok in Podolia, where from 1892 he owned a huge estate. In fact, while working as the director of the Institute of Experimental Medicine, Winogradsky renounced his salary, which was transferred to a special account, and then used these funds to build a room for a scientific library, the director of which lived on the income from the estate, where agricultural work was carried out.
In Gorodok Winogradsky addressed the problems of agriculture and soil science. He introduced new management methods, bought the best varieties of seeds, plants, and livestock, and advanced technology. His estate became one of the richest and most successful in Podolia, and remained profitable even during the First World War, falling under Austro-Hungarian occupation.
He retired from active scientific work in 1905, dividing his time between his private estate in Gorodok and Switzerland.
After the revolution of 1917, Winogradsky went first to Switzerland and then to Belgrade. In 1922, he accepted an invitation to head the Pasteur Institute's division of agricultural bacteriology at an experimental station at Brie-Comte-Robert, France, about 30 km from Paris. During this period, he worked on a number of topics, among them iron bacteria, nitrifying bacteria, nitrogen fixation by Azotobacter, cellulose-decomposing bacteria, and culture methods for soil microorganisms. In 1923 Winogradsky became an honorary member of the Russian Academy of Sciences despite his emigration. He retired from active life in 1940 and died in Brie-Comte-Robert in 1953.
Discoveries
Winogradsky discovered various biogeochemical cycles and parts of these cycles. These discoveries include
His work on bacterial sulfide oxidation for which he first became renowned, including the first known form of lithotrophy (in Beggiatoa).
His work on the Nitrogen cycle including
The identification of the obligate anaerobe Clostridium pasteurianum is a free living microbe capable of fixing atmospheric nitrogen and not living in legume root nodules.
Chemosynthesis – his most noted discovery
The Winogradsky column
Chemosynthesis
Winogradsky is best known for discovering chemoautotrophy, which soon became popularly known as chemosynthesis, the process by which organisms derive energy from a number of different inorganic compounds and obtain carbon in the form of carbon dioxide. Previously, it was believed that autotrophs obtained their energy solely from light, not from reactions of inorganic compounds. With the discovery of organisms that oxidized inorganic compounds such as hydrogen sulfide and ammonium as energy sources, autotrophs could be divided into two groups: photoautotrophs and chemoautotrophs. Winogradsky was one of the first researchers to attempt to understand microorganisms outside of the medical context, making him among the first students of microbial ecology and environmental microbiology.
The Winogradsky column remains an important display of chemoautotrophy and microbial ecology, demonstrated in microbiology lectures around the world.
Memorials
The Institute of Microbiology of the Russian Academy of Sciences bears Winogradsky's name since 2003.
In 2012, a bust of the scientist was unveiled on the grounds of his former estate in Horodok, Khmelnytskyi Oblast, Ukraine.
In Ukraine, the study and popularization of the life and activities of Sergey Winogradsky are promoted by the Winogradsky Club, whose centre is located in the Horodok Museum of Local History (G-MUSEUM). One of the museum's exhibitions is a reconstruction of Winogradsky's laboratory in Brie-Comte-Robert including a wax figure of the scientist.
See also
Hermann Hellriegel
Martinus Beijerinck
Further reading
Ackert, Lloyd. Sergei Vinogradskii and the Cycle of Life: From the Thermodynamics of Life to Ecological Microbiology, 1850-1950. Vol. 34.; Dordrecht; London: Springer, 2013.
References
External links
Sergei Winogradsky at Cycle of Life website including images.
page Winogradsky Club
official website G-Museum
1856 births
1953 deaths
Environmental microbiology
Foreign members of the Royal Society
Former Russian Orthodox Christians
Nitrogen cycle
Ukrainian biochemists
Ukrainian microbiologists
Ukrainian biologists
Ukrainian ecologists
Leeuwenhoek Medal winners
Academic staff of the University of Strasbourg
Russian scientists | Sergei Winogradsky | [
"Chemistry",
"Environmental_science"
] | 1,550 | [
"Environmental microbiology",
"Nitrogen cycle",
"Metabolism"
] |
2,150,306 | https://en.wikipedia.org/wiki/SPL%20notation | SPL (Sentence Plan Language) is an abstract notation representing the semantics of a sentence in natural language. In a classical Natural Language Generation (NLG) workflow, an initial text plan (hierarchically or sequentially organized factoids, often modelled in accordance with Rhetorical Structure Theory) is transformed by a sentence planner (generator) component to a sequence of sentence plans modelled in a Sentence Plan Language. A surface generator can be used to transform the SPL notation into natural language sentences.
Probably the most widely used SPL language used today (2022) is AMR (Abstract Meaning Representation, see there for further references), but is owes parts of its popularity to its application to NLP problems other than NLG, e.g., machine translation and semantic parsing.
See also
Natural language generation
References
Natural language processing | SPL notation | [
"Technology"
] | 169 | [
"Natural language processing",
"Natural language and computing"
] |
2,150,441 | https://en.wikipedia.org/wiki/Quantifier%20elimination | Quantifier elimination is a concept of simplification used in mathematical logic, model theory, and theoretical computer science. Informally, a quantified statement " such that " can be viewed as a question "When is there an such that ?", and the statement without quantifiers can be viewed as the answer to that question.
One way of classifying formulas is by the amount of quantification. Formulas with less depth of quantifier alternation are thought of as being simpler, with the quantifier-free formulas as the simplest.
A theory has quantifier elimination if for every formula , there exists another formula without quantifiers that is equivalent to it (modulo this theory).
Examples
An example from mathematics says that a single-variable quadratic polynomial has a real root if and only if its discriminant is non-negative:
Here the sentence on the left-hand side involves a quantifier , whereas the equivalent sentence on the right does not.
Examples of theories that have been shown decidable using quantifier elimination are Presburger arithmetic, algebraically closed fields, real closed fields, atomless Boolean algebras, term algebras, dense linear orders, abelian groups, random graphs, as well as many of their combinations such as Boolean algebra with Presburger arithmetic, and term algebras with queues.
Quantifier eliminator for the theory of the real numbers as an ordered additive group is Fourier–Motzkin elimination; for the theory of the field of real numbers it is the Tarski–Seidenberg theorem.
Quantifier elimination can also be used to show that "combining" decidable theories leads to new decidable theories (see Feferman–Vaught theorem).
Algorithms and decidability
If a theory has quantifier elimination, then a specific question can be addressed: Is there a method of determining for each ? If there is such a method we call it a quantifier elimination algorithm. If there is such an algorithm, then decidability for the theory reduces to deciding the truth of the quantifier-free sentences. Quantifier-free sentences have no variables, so their validity in a given theory can often be computed, which enables the use of quantifier elimination algorithms to decide validity of sentences.
Related concepts
Various model-theoretic ideas are related to quantifier elimination, and there are various equivalent conditions.
Every first-order theory with quantifier elimination is model complete. Conversely, a model-complete theory, whose theory of universal consequences has the amalgamation property, has quantifier elimination.
The models of the theory of the universal consequences of a theory are precisely the substructures of the models of . The theory of linear orders does not have quantifier elimination. However the theory of its universal consequences has the amalgamation property.
Basic ideas
To show constructively that a theory has quantifier elimination, it suffices to show that we can eliminate an existential quantifier applied to a conjunction of literals, that is, show that each formula of the form:
where each is a literal, is equivalent to a quantifier-free formula. Indeed, suppose we know how to eliminate quantifiers from conjunctions of literals, then if is a quantifier-free formula, we can write it in disjunctive normal form
and use the fact that
is equivalent to
Finally, to eliminate a universal quantifier
where is quantifier-free, we transform
into disjunctive normal form, and use the fact that
is equivalent to
Relationship with decidability
In early model theory, quantifier elimination was used to demonstrate that various theories possess properties like decidability and completeness. A common technique was to show first that a theory admits elimination of quantifiers and thereafter prove decidability or completeness by considering only the quantifier-free formulas. This technique can be used to show that Presburger arithmetic is decidable.
Theories could be decidable yet not admit quantifier elimination. Strictly speaking, the theory of the additive natural numbers did not admit quantifier elimination, but it was an expansion of the additive natural numbers that was shown to be decidable. Whenever a theory is decidable, and the language of its valid formulas is countable, it is possible to extend the theory with countably many relations to have quantifier elimination (for example, one can introduce, for each formula of the theory, a relation symbol that relates the free variables of the formula).
Example: Nullstellensatz for algebraically closed fields and for differentially closed fields.
See also
Cylindrical algebraic decomposition
Elimination theory
Conjunction elimination
Notes
References
, see for an English translation
Model theory | Quantifier elimination | [
"Mathematics"
] | 1,008 | [
"Mathematical logic",
"Model theory"
] |
2,150,531 | https://en.wikipedia.org/wiki/Counting%20quantification | A counting quantifier is a mathematical term for a quantifier of the form "there exists at least k elements that satisfy property X".
In first-order logic with equality, counting quantifiers can be defined in terms of ordinary quantifiers, so in this context they are a notational shorthand.
However, they are interesting in the context of logics such as two-variable logic with counting that restrict the number of variables in formulas.
Also, generalized counting quantifiers that say "there exists infinitely many" are not expressible using a finite number of formulas in first-order logic.
Definition in terms of ordinary quantifiers
Counting quantifiers can be defined recursively in terms of ordinary quantifiers.
Let denote "there exist exactly ". Then
Let denote "there exist at least ". Then
See also
Uniqueness quantification
Lindström quantifier
Spectrum of a sentence
References
Erich Graedel, Martin Otto, and Eric Rosen. "Two-Variable Logic with Counting is Decidable." In Proceedings of 12th IEEE Symposium on Logic in Computer Science LICS `97, Warschau. 1997. Postscript file
Quantifier (logic) | Counting quantification | [
"Mathematics"
] | 255 | [
"Predicate logic",
"Mathematical logic",
"Quantifier (logic)",
"Basic concepts in set theory"
] |
2,150,535 | https://en.wikipedia.org/wiki/PGPfone | PGPfone was a secure voice telephony system developed by Philip Zimmermann in 1995. The PGPfone protocol had little in common with Zimmermann's popular PGP email encryption package, except for the use of the name. It used ephemeral Diffie-Hellman protocol to establish a session key, which was then used to encrypt the stream of voice packets. The two parties compared a short authentication string to detect a Man-in-the-middle attack, which is the most common method of wiretapping secure phones of this type. PGPfone could be used point-to-point (with two modems) over the public switched telephone network, or over the Internet as an early Voice over IP system.
In 1996, there were no protocol standards for Voice over IP. Ten years later, Zimmermann released the successor to PGPfone, Zfone and ZRTP, a newer and secure VoIP protocol based on modern VoIP standards. Zfone builds on the ideas of PGPfone.
According to the MIT PGPfone web page, "MIT is no longer distributing PGPfone. Given that the software has not been maintained since 1997, we doubt it would run on most modern systems."
See also
Comparison of VoIP software
Nautilus (secure telephone)
PGP word list
Secure telephone
References
External links
PGPfone homepage on PGPi
Old PGPfone homepage on MIT
PGPfone sources, modified to build on modern systems
Discontinued software
Secure communication
Cryptographic software
VoIP software | PGPfone | [
"Mathematics"
] | 317 | [
"Cryptographic software",
"Mathematical software"
] |
2,150,549 | https://en.wikipedia.org/wiki/Oxidative%20stress | Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal redox state of cells can cause toxic effects through the production of peroxides and free radicals that damage all components of the cell, including proteins, lipids, and DNA. Oxidative stress from oxidative metabolism causes base damage, as well as strand breaks in DNA. Base damage is mostly indirect and caused by the reactive oxygen species generated, e.g., (superoxide radical), OH (hydroxyl radical) and (hydrogen peroxide). Further, some reactive oxidative species act as cellular messengers in redox signaling. Thus, oxidative stress can cause disruptions in normal mechanisms of cellular signaling.
In humans, oxidative stress is thought to be involved in the development of attention deficit hyperactivity disorder, cancer, Parkinson's disease, Lafora disease, Alzheimer's disease, atherosclerosis, heart failure, myocardial infarction, fragile X syndrome, sickle-cell disease, lichen planus, vitiligo, autism, infection, chronic fatigue syndrome, and depression; however, reactive oxygen species can be beneficial, as they are used by the immune system as a way to attack and kill pathogens. Short-term oxidative stress may also be important in prevention of aging by induction of a process named mitohormesis, and is required to initiate stress response processes in plants.
Chemical and biological effects
Chemically, oxidative stress is associated with increased production of oxidizing species or a significant decrease in the effectiveness of antioxidant defenses, such as glutathione. The effects of oxidative stress depend upon the size of these changes, with a cell being able to overcome small perturbations and regain its original state. However, more severe oxidative stress can cause cell death, and even moderate oxidation can trigger apoptosis, while more intense stresses may cause necrosis.
Production of reactive oxygen species is a particularly destructive aspect of oxidative stress. Such species include free radicals and peroxides. Some of the less reactive of these species (such as superoxide) can be converted by oxidoreduction reactions with transition metals or other redox cycling compounds (including quinones) into more aggressive radical species that can cause extensive cellular damage. Most long-term effects are caused by damage to DNA. DNA damage induced by ionizing radiation is similar to oxidative stress, and these lesions have been implicated in aging and cancer. Biological effects of single-base damage by radiation or oxidation, such as 8-oxoguanine and thymine glycol, have been extensively studied. Recently the focus has shifted to some of the more complex lesions. Tandem DNA lesions are formed at substantial frequency by ionizing radiation and metal-catalyzed reactions. Under anoxic conditions, the predominant double-base lesion is a species in which C8 of guanine is linked to the 5-methyl group of an adjacent 3'-thymine (G[8,5- Me]T). Most of these oxygen-derived species are produced by normal aerobic metabolism. Normal cellular defense mechanisms destroy most of these. Repair of oxidative damages to DNA is frequent and ongoing, largely keeping up with newly induced damages. In rat urine, about 74,000 oxidative DNA adducts per cell are excreted daily. There is also a steady state level of oxidative damages in the DNA of a cell. There are about 24,000 oxidative DNA adducts per cell in young rats and 66,000 adducts per cell in old rats. Likewise, any damage to cells is constantly repaired. However, under the severe levels of oxidative stress that cause necrosis, the damage causes ATP depletion, preventing controlled apoptotic death and causing the cell to simply fall apart.
Polyunsaturated fatty acids, particularly arachidonic acid and linoleic acid, are primary targets for free radical and singlet oxygen oxidations. For example, in tissues and cells, the free radical oxidation of linoleic acid produces racemic mixtures of 13-hydroxy-9Z,11E-octadecadienoic acid, 13-hydroxy-9E,11E-octadecadienoic acid, 9-hydroxy-10E,12-E-octadecadienoic acid (9-EE-HODE), and 11-hydroxy-9Z,12-Z-octadecadienoic acid as well as 4-Hydroxynonenal while singlet oxygen attacks linoleic acid to produce (presumed but not yet proven to be racemic mixtures of) 13-hydroxy-9Z,11E-octadecadienoic acid, 9-hydroxy-10E,12-Z-octadecadienoic acid, 10-hydroxy-8E,12Z-octadecadienoic acid, and 12-hydroxy-9Z-13-E-octadecadienoic (see 13-Hydroxyoctadecadienoic acid and 9-Hydroxyoctadecadienoic acid). Similar attacks on arachidonic acid produce a far larger set of products including various isoprostanes, hydroperoxy- and hydroxy- eicosatetraenoates, and 4-hydroxyalkenals. While many of these products are used as markers of oxidative stress, the products derived from linoleic acid appear far more predominant than arachidonic acid products and therefore easier to identify and quantify in, for example, atheromatous plaques. Certain linoleic acid products have also been proposed to be markers for specific types of oxidative stress. For example, the presence of racemic 9-HODE and 9-EE-HODE mixtures reflects free radical oxidation of linoleic acid whereas the presence of racemic 10-hydroxy-8E,12Z-octadecadienoic acid and 12-hydroxy-9Z-13-E-octadecadienoic acid reflects singlet oxygen attack on linoleic acid. In addition to serving as markers, the linoleic and arachidonic acid products can contribute to tissue and/or DNA damage but also act as signals to stimulate pathways which function to combat oxidative stress.
Table adapted from.
Production and consumption of oxidants
One source of reactive oxygen under normal conditions in humans is the leakage of activated oxygen from mitochondria during oxidative phosphorylation. E. coli mutants that lack an active electron transport chain produce as much hydrogen peroxide as wild-type cells, indicating that other enzymes contribute the bulk of oxidants in these organisms. One possibility is that multiple redox-active flavoproteins all contribute a small portion to the overall production of oxidants under normal conditions.
Other enzymes capable of producing superoxide are xanthine oxidase, NADPH oxidases and cytochromes P450. Hydrogen peroxide is produced by a wide variety of enzymes including several oxidases. Reactive oxygen species play important roles in cell signalling, a process termed redox signaling. Thus, to maintain proper cellular homeostasis, a balance must be struck between reactive oxygen production and consumption.
The best studied cellular antioxidants are the enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase. Less well studied (but probably just as important) enzymatic antioxidants are the peroxiredoxins and the recently discovered sulfiredoxin. Other enzymes that have antioxidant properties (though this is not their primary role) include paraoxonase, glutathione-S transferases, and aldehyde dehydrogenases.
The amino acid methionine is prone to oxidation, but oxidized methionine can be reversible. Oxidation of methionine is shown to inhibit the phosphorylation of adjacent Ser/Thr/Tyr sites in proteins. This gives a plausible mechanism for cells to couple oxidative stress signals with cellular mainstream signaling such as phosphorylation.
Diseases
Oxidative stress is suspected to be important in neurodegenerative diseases including Lou Gehrig's disease (aka MND or ALS), Parkinson's disease, Alzheimer's disease, Huntington's disease, depression, and multiple sclerosis. It is also indicated in Neurodevelopmental conditions such as Autism Spectrum Disorder. Indirect evidence via monitoring biomarkers such as reactive oxygen species, and reactive nitrogen species production indicates oxidative damage may be involved in the pathogenesis of these diseases, while cumulative oxidative stress with disrupted mitochondrial respiration and mitochondrial damage are related to Alzheimer's disease, Parkinson's disease, and other neurodegenerative diseases.
Oxidative stress is thought to be linked to certain cardiovascular disease, since oxidation of LDL in the vascular endothelium is a precursor to plaque formation. Oxidative stress also plays a role in the ischemic cascade due to oxygen reperfusion injury following hypoxia. This cascade includes both strokes and heart attacks. Oxidative stress has also been implicated in chronic fatigue syndrome (ME/CFS). Oxidative stress also contributes to tissue injury following irradiation and hyperoxia, as well as in diabetes. In hematological cancers, such as leukemia, the impact of oxidative stress can be bilateral. Reactive oxygen species can disrupt the function of immune cells, promoting immune evasion of leukemic cells. On the other hand, high levels of oxidative stress can also be selectively toxic to cancer cells.
Oxidative stress is likely to be involved in age-related development of cancer. The reactive species produced in oxidative stress can cause direct damage to the DNA and are therefore mutagenic, and it may also suppress apoptosis and promote proliferation, invasiveness and metastasis. Infection by Helicobacter pylori which increases the production of reactive oxygen and nitrogen species in human stomach is also thought to be important in the development of gastric cancer.
Oxidative stress can cause DNA damage in neurons. In neuronal progenitor cells, DNA damage is associated with increased secretion of amyloid beta proteins Aβ40 and Aβ42. This association supports the existence of a causal relationship between oxidative DNA damage and Aβ accumulation and suggests that oxidative DNA damage may contribute to Alzheimer's disease (AD) pathology. AD is associated with an accumulation of DNA damage (double-strand breaks) in vulnerable neuronal and glial cell populations from early stages onward, and DNA double-strand breaks are increased in the hippocampus of AD brains compared to non-AD control brains.
Antioxidants as supplements
The use of antioxidants to prevent some diseases is controversial. In a high-risk group like smokers, high doses of beta carotene increased the rate of lung cancer since high doses of beta-carotene in conjunction of high oxygen tension due to smoking results in a pro-oxidant effect and an antioxidant effect when oxygen tension is not high. In less high-risk groups, the use of vitamin E appears to reduce the risk of heart disease. However, while consumption of food rich in vitamin E may reduce the risk of coronary heart disease in middle-aged to older men and women, using vitamin E supplements also appear to result in an increase in total mortality, heart failure, and hemorrhagic stroke. The American Heart Association therefore recommends the consumption of food rich in antioxidant vitamins and other nutrients, but does not recommend the use of vitamin E supplements to prevent cardiovascular disease. In other diseases, such as Alzheimer's, the evidence on vitamin E supplementation is also mixed. Since dietary sources contain a wider range of carotenoids and vitamin E tocopherols and tocotrienols from whole foods, ex post facto epidemiological studies can have differing conclusions than artificial experiments using isolated compounds. AstraZeneca's radical scavenging nitrone drug NXY-059 shows some efficacy in the treatment of stroke.
Oxidative stress (as formulated in Denham Harman's free-radical theory of aging) is also thought to contribute to the aging process. While there is good evidence to support this idea in model organisms such as Drosophila melanogaster and Caenorhabditis elegans, recent evidence from Michael Ristow's laboratory suggests that oxidative stress may also promote life expectancy of Caenorhabditis elegans by inducing a secondary response to initially increased levels of reactive oxygen species. The situation in mammals is even less clear. Recent epidemiological findings support the process of mitohormesis, but a 2007 meta-analysis finds that in studies with a low risk of bias (randomization, blinding, follow-up), some popular antioxidant supplements (vitamin A, beta carotene, and vitamin E) may increase mortality risk (although studies more prone to bias reported the reverse).
The USDA removed the table showing the Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods Release 2 (2010) table due to the lack of evidence that the antioxidant level present in a food translated into a related antioxidant effect in the body.
Metal catalysts
Metals such as iron, copper, chromium, vanadium, and cobalt are capable of redox cycling in which a single electron may be accepted or donated by the metal. This action catalyzes production of reactive radicals and reactive oxygen species. The presence of such metals in biological systems in an uncomplexed form (not in a protein or other protective metal complex) can significantly increase the level of oxidative stress. These metals are thought to induce Fenton reactions and the Haber-Weiss reaction, in which hydroxyl radical is generated from hydrogen peroxide. The hydroxyl radical then can modify amino acids. For example, meta-tyrosine and ortho-tyrosine form by hydroxylation of phenylalanine. Other reactions include lipid peroxidation and oxidation of nucleobases. Metal-catalyzed oxidations also lead to irreversible modification of arginine, lysine, proline, and threonine. Excessive oxidative-damage leads to protein degradation or aggregation.
The reaction of transition metals with proteins oxidated by reactive oxygen or nitrogen species can yield reactive products that accumulate and contribute to aging and disease. For example, in Alzheimer's patients, peroxidized lipids and proteins accumulate in lysosomes of the brain cells.
Non-metal redox catalysts
Certain organic compounds in addition to metal redox catalysts can also produce reactive oxygen species. One of the most important classes of these is the quinones. Quinones can redox cycle with their conjugate semiquinones and hydroquinones, in some cases catalyzing the production of superoxide from dioxygen or hydrogen peroxide from superoxide.
Immune defense
The immune system uses the lethal effects of oxidants by making the production of oxidizing species a central part of its mechanism of killing pathogens; with activated phagocytes producing both reactive oxygen and nitrogen species. These include superoxide , nitric oxide (•NO) and their particularly reactive product, peroxynitrite (ONOO-). Although the use of these highly reactive compounds in the cytotoxic response of phagocytes causes damage to host tissues, the non-specificity of these oxidants is an advantage since they will damage almost every part of their target cell. This prevents a pathogen from escaping this part of immune response by mutation of a single molecular target.
Male infertility
Sperm DNA fragmentation appears to be an important factor in the cause of male infertility, since men with high DNA fragmentation levels have significantly lower odds of conceiving. Oxidative stress is the major cause of DNA fragmentation in spermatozoa. A high level of the oxidative DNA damage 8-oxo-2'-deoxyguanosine is associated with abnormal spermatozoa and male infertility.
Aging
In a rat model of premature aging, oxidative stress induced DNA damage in the neocortex and hippocampus was substantially higher than in normally aging control rats. Numerous studies have shown that the level of 8-oxo-2'-deoxyguanosine, a product of oxidative stress, increases with age in the brain and muscle DNA of the mouse, rat, gerbil and human. Further information on the association of oxidative DNA damage with aging is presented in the article DNA damage theory of aging. However, it was recently shown that the fluoroquinolone antibiotic Enoxacin can diminish aging signals and promote lifespan extension in nematodes C. elegans by inducing oxidative stress.
Origin of eukaryotes
The great oxygenation event began with the biologically induced appearance of oxygen in the Earth's atmosphere about 2.45 billion years ago. The rise of oxygen levels due to cyanobacterial photosynthesis in ancient microenvironments was probably highly toxic to the surrounding biota. Under these conditions, the selective pressure of oxidative stress is thought to have driven the evolutionary transformation of an archaeal lineage into the first eukaryotes. Oxidative stress might have acted in synergy with other environmental stresses (such as ultraviolet radiation and/or desiccation) to drive this selection. Selective pressure for efficient repair of oxidative DNA damages may have promoted the evolution of eukaryotic sex involving such features as cell-cell fusions, cytoskeleton-mediated chromosome movements and emergence of the nuclear membrane. Thus, the evolution of meiotic sex and eukaryogenesis may have been inseparable processes that evolved in large part to facilitate repair of oxidative DNA damages.
COVID-19 and cardiovascular injury
It has been proposed that oxidative stress may play a major role in determining cardiac complications in COVID-19.
See also
Antioxidative stress
Acatalasia
Bruce Ames
Malondialdehyde, an oxidative stress marker
Mitochondrial free radical theory of aging
Mitohormesis
Nitric oxide
Pro-oxidant
Reductive stress
References
Cell biology
Chemical pathology
Alzheimer's disease
Senescence | Oxidative stress | [
"Chemistry",
"Biology"
] | 3,923 | [
"Cell biology",
"Senescence",
"Cellular processes",
"Biochemistry",
"Chemical pathology",
"Metabolism"
] |
2,150,591 | https://en.wikipedia.org/wiki/Theodore%20Freeman | Theodore Cordy Freeman (February 18, 1930 – October 31, 1964), was an American aeronautical engineer, U.S. Air Force officer, test pilot, and NASA astronaut. Selected in the third group of NASA astronauts in 1963, he was killed a year later in the crash of a T-38 jet, marking the first fatality among the NASA Astronaut Corps. At the time of his death, he held the rank of captain.
Early life
Born in Haverford, Pennsylvania, on February 18, 1930, Freeman was named after the man who raised his father (Theodore Cullen Donovan), as well as his maternal grandfather (Thomas Cordy Wilson). He was one of five children. Raised in Lewes, Delaware, he attended Lewes Elementary School from 1936 to 1944. His father was a farmer and his brother a carpenter, and it seemed as if he would also have a blue collar career. When Freeman and his brother were young, they saved up money so they could take plane rides. He also was a part-time worker, helping to refuel the planes and work on them. He spent most of his money on flying lessons, and with over 450 hours of flying on his training record, earned his pilot's license by the age of 16. "I sort of grew up at the airport," Freeman said.
Freeman played baseball and football in high school. While playing football, he was hit hard and his teeth were knocked out of alignment. He was the president of the school's student and the local chapter of the National Honor Society; he graduated as an honors student ranked third in his class in 1948.
He was a Boy Scout and he earned the rank of First Class.
Education
During his senior year of high school, Freeman completed the application to the United States Naval Academy. He passed the scholarship portion, but failed the medical portion due to his crooked teeth. He was told if he straightened them out he would be accepted the next year.
During that year, Freeman attended the University of Delaware at Newark to further his education. He also made some money by spotting schools of fish for local fishermen. Freeman had an operation to fix his teeth, which included grinding his teeth down, then wore braces for several months to finish the effort. He was admitted to the U.S. Naval Academy Class of 1953 on June 17, 1949. Freeman graduated from Annapolis in 1953 with a Bachelor of Science degree. In 1960, he received a Master of Science degree in aeronautical engineering from the University of Michigan.
Military and NASA career
Freeman elected to enter the U.S. Air Force and took flight training at Hondo Air Force Base and Bryan Air Force Base, Texas and at Nellis Air Force Base, Nevada. He was awarded his pilot wings in February 1955, shortly after being promoted to first lieutenant, then served in the Pacific and at George Air Force Base, California. He was promoted to captain in June 1960 while pursuing his master's degree at the University of Michigan and then went to Edwards Air Force Base, California, in February 1960 as an aerospace engineer.
Freeman graduated from both the Air Force's Experimental Test Pilot School (Class 62A) and Aerospace Research Pilot School (Class IV) courses. He elected to serve with the Air Force. His last Air Force assignment was as a flight test aeronautical engineer and experimental flight test instructor at the ARPS at Edwards AFB in the Mojave Desert.
Freeman served primarily in performance flight testing and stability testing areas; he logged more than 3,300 hours flying time, including more than 2,400 hours in jet aircraft. Freeman was one of the third group of astronauts selected by NASA in October 1963 and was assigned the responsibility of aiding the development of boosters.
Death
Freeman died in a plane crash due to a bird strike on the morning of October 31, 1964. After a delay caused by fog, he piloted a T-38A Talon from St. Louis to Houston. Freeman was returning on Saturday from McDonnell training facilities in St. Louis and crashed during final approach to landing at Ellington Air Force Base in Houston. There were reports of geese due to the fog, one of which flew into the port-side air intake of his NASA-modified T-38 jet trainer, causing the engine to flame out. Flying shards of Plexiglas entered the jet engine during the crash.
Freeman attempted to land on the runway, but realized he was too short and might hit military housing. He banked away from the runway and ejected. The jet had nosed down a considerable amount, and he ejected nearly horizontally. Freeman's parachute did not deploy in time, and he died upon impact with the ground; his skull was fractured and he had severe chest injuries.
Personal life
Freeman was married with one daughter. His wife first heard of her husband's death when a Houston reporter, Jim Schefter, arrived at her house; NASA subsequently ensured that in the case of future astronaut deaths, the families would be informed by other astronauts as quickly as possible. Freeman was buried with full military honors in Arlington National Cemetery. Five astronauts were pallbearers at the funeral.
Honors
The Clear Lake City-County Freeman Branch Library of the Harris County Public Library and Houston Public Library systems is named in memory of Freeman. An artificial island off Long Beach is also named for him. This is one of the four "Astronaut Islands" built in Long Beach Harbor during the late 1960s as unsinkable platforms for oil drilling; the others were named Grissom, White and Chaffee, in honor of the astronauts killed in the Apollo 1 fire. A crater on the far side of the Moon was temporarily named Freeman crater by the Apollo 8 crew. The Theodore C. Freeman Highway in Lewes, Delaware, an approach road to the Cape May–Lewes Ferry which carries U.S. Route 9, was named after him by a resolution of the Delaware Senate on December 21, 1965. A plaque commemorating Freeman was unveiled at the Lewes terminal of the Cape May–Lewes Ferry on June 18, 2014, with Governor Jack Markell and family members of Freeman in attendance at the ceremony.
Books
Oriana Fallaci's 1965 book about the early days of the American space program, If the Sun Dies, features an account of Freeman.
See also
Fallen Astronaut sculpture
List of spaceflight-related accidents and incidents
References
Bibliography
External links
Astronautix biography of Theodore C. Freeman
Theodore C. Freeman at Astronauts Memorial page
ANC Explorer
1930 births
1964 deaths
Accidental deaths in Texas
American aerospace engineers
American flight instructors
American test pilots
Aviators from Pennsylvania
Aviators killed in aviation accidents or incidents in the United States
Burials at Arlington National Cemetery
Engineers from Pennsylvania
Military personnel from Pennsylvania
People from Haverford Township, Pennsylvania
People from Lewes, Delaware
Space program fatalities
20th-century American engineers
United States Air Force astronauts
United States Air Force officers
United States Naval Academy alumni
University of Delaware alumni
University of Michigan College of Engineering alumni
U.S. Air Force Test Pilot School alumni
Victims of aviation accidents or incidents in 1964 | Theodore Freeman | [
"Engineering"
] | 1,420 | [
"Space program fatalities",
"Space programs"
] |
2,150,852 | https://en.wikipedia.org/wiki/SipXecs | SipXecs is a free software enterprise communications system. It was initially developed by Pingtel Corporation in 2003 as a voice over IP telephony server located in Boston, MA. The server was later extended with additional collaboration capabilities as part of the SIPfoundry project. Since its extension, sipXecs now acts as a software implementation of the Session Initiation Protocol (SIP), making it a full IP-based communications system.
SipXecs competitors include other open-source telephony and SoftSwitch solutions such as Asterisk, FreeSWITCH, and the SIP Express Router.
History
Development of sipXecs began in 2003 by Pingtel Corporation. In 2004, Pingtel adopted an open-source business model and contributed the codebase to the not-for-profit organization SIPfoundry. It has been an open source project since then.
Pingtel's assets were acquired by Bluesocket in July 2007. In August 2008 the Pingtel assets were acquired from Bluesocket by Nortel. Subsequent to the acquisition by Nortel, Nortel released the SCS500 product based on sipXecs. SCS500 was positioned as an open and software-only telephony server for the SMB market up to 500 users and received some recognition. It was later renamed SCS and positioned as an enterprise communications system.
Subsequent to the Nortel bankruptcy and the acquisition of the Nortel assets by Avaya, sipXecs continued to be used as the basis for the Avaya Live cloud based communications service.
In April 2010 the founders of SIPfoundry founded , a commercial version of the software.
Information
SipXecs is designed as a software-only, distributed cloud application. It runs on the Linux operating system CentOS or RHEL on either virtualized or physical servers. A minimum configuration allows running all of the sipXecs components on a single server, including database, all available services, and the sipXecs management. Global clusters can be built using built-in auto-configuration capabilities from the centralized management system.
SipXecs uses MongoDB as a distributed and partition tolerant database for global transactions, includes CFEngine for orchestration of clusters and JasperReports for reporting. The management and configuration system is based on the Spring Framework. sipXecs includes FreeSWITCH as its media server and Openfire for presence and instant messaging services.
SipXecs follows standards such as Session Initiation Protocol (SIP), SRTP, Extensible Messaging and Presence Protocol (XMPP), SIP and XMPP over TLS, and several Web standards including WebRTC, WebSOCKET and Representational State Transfer (REST).
Adoption
Amazon.com was an early adopter of sipXecs. This initial 5,000 user deployment expanded considerably in the following years.
OnRelay, a company in the UK, selected sipXecs for its fixed-mobile convergence solution sold to carriers.
Colorado State University and Cedarville University of Ohio committed to sipXecs in 2010.
Red Hat deployed a commercial version of sipXecs from globally in 2012.
Under the SIPfoundry Higher Education Program (HEP) and as of 2014 Lafayette College, St. Mary's University, Messiah College, Colorado School of Mines, Carthage College deployed sipXecs to replace their respective PBX systems.
SipXecs is used by small and large enterprises ranging up to about 20,000 users per cluster. SIPfoundry lists the following users on its Web site: Brevard County FL, Dutch Police, Easter Seals, Siemens Transportation, British Airways.
Availability
SipXecs is available for Red Hat Linux and CentOS. It runs virtualized in different cloud environments such as the Amazon Elastic Compute Cloud, the Google Compute Engine, the HP Cloud, IBM SoftLayer, VMware vCloud and VMware ESX, OpenStack environments, and clouds from other vendors using these technologies.
Licensing and Copyright
SIPfoundry distributes the sipXecs source code under the AGPL-3.0-or-later license.
Many different corporate and individual contributors contributed to sipXecs, including Pingtel, Bluesocket, Nortel, Avaya, and as some of the larger corporate contributors representing 864,791 lines of code. In addition, the sipXecs solution includes many other open-source components. SIPfoundry holds Copyright on all derivative work. Contributions to sipXecs are made under a Contributor Agreement, which grants SIPfoundry shared Copyright with the original author on all contributed code.
Hardware
SipXecs supports a wide range of SIP compatible hardware, such as PSTN gateways, desk phones, softphones and mobile phone applications. A plug n'play auto-configuration capability is available for phones from currently (software release 14.04) 18 different vendors.
SIP reference implementation
The SipXecs system represents a reference implementation of the SIP standard. It was used at SIPIT interoperability events organized by the SIP Forum to test interoperability of SIP solutions from many different vendors.
See also
Comparison of VoIP software
List of free and open-source software packages
List of SIP software
References
External links
SIPfoundry official website
Collaborative software
Free VoIP software
Instant messaging
Open-source cloud applications
Software using the GNU Affero General Public License | SipXecs | [
"Technology"
] | 1,111 | [
"Instant messaging"
] |
2,150,880 | https://en.wikipedia.org/wiki/Train%20event%20recorder | A train event recorder – also called On-Train Monitoring Recorder (OTMR), On-Train Data Recorder (OTDR), Event Recorder System (ERS), Event Recorder Unit (ERU), or Juridical Recording Unit (JRU) – is a device that records data about the operation of train controls, the performance of the train in response to those controls, and the operation of associated control systems. It is similar in purpose to the flight data recorder or black box used on aircraft.
Functions
Because event recorders are integrated with most car-borne systems, they are an attractive target for enhanced diagnostic and control functions. Some event recorders feature outputs controlling penalty braking or emergency braking systems, as well as speedometers.
Data storage can be provided by magnetic tape, battery-backed RAM and, more recently, non-volatile EEPROM or flash memory, overwritten in a FIFO continuous loop. The data is intended for use in the investigation of accidents and other incidents, but is also used to monitor the performance of traction units, the competence of drivers, and the general state of a train over a period of time.
Development
A suggestion in The Times of 10 October 1853, commenting on a train collision near Portarlington station, on the Great Southern and Western Railway, on 5 October that year, called for a paper-roll recorder, keeping a log of wheel revolutions against time, to be carried in a locked box on trains, the record to be removed and stored by station masters at the destination station. In 1864, a similar proposal came from Charles Babbage, inspired by his 1840 experiments for the Great Western Railway using self-inking pens on paper rolls, which were part of the equipment carried on dynamometer cars. No action seems to have been taken in either case. The earliest event recorders were the mechanical "TEL" speed recorders of 1891, which recorded both time and speed. The TEL's manufacturer, Hasler Rail of Switzerland, remains a leading producer of train event recorders.
France developed the Flaman Speed Indicator and Recorder. In Germany, the Indusi train protection system included recording equipment using a ticker tape on paper. For I60R a generalized recorder system was installed (Datenspeicherkassette [DSK] / data storage cassette) that allowed for the entry of the train number, driver information and train weight, along with the driving events. The standardized DSK black box allows for approximately 30,000 km of general recording data and 90 km of detailed recording data. Later models of the DSK are electronic especially since the introduction of the computerized PZ80/PZB90 train protection generations.
Modern train event recorders follow international or national standards, such as IEEE Std. 1482.1-1999, FRA 49 CFR Part 229, and IEC 62625-1, specified the digital and analogue data to be acquired, recorded and transmitted for further analysis. The need for event recorders to survive any accident led companies such as Grinsty Rail (UK), Faiveley (France), Hasler Rail (Switzerland), Bach-Simpson (Canada), Saira Electronics (Italy) (previously FAR Systems), and MIOS Elettronica (Italy) to develop crash-protected memory modules as a part of their event recorders. Those new-generation event recorders are in growing demand both for rapid transit systems and mainline trains.
Regulations
Canada
Canadian regulations provide in the "Locomotives Design Requirements (Part II)"
"12. Event Recorders. 12.1 Controlling locomotives other than in designated and/or yard service, shall be equipped with an event recorder meeting the following minimum design criteria: The event recorder shall record time, distance, speed, brake pipe pressure, throttle position, emergency brake application, independent brake cylinder pressure, horn signal and Reset Safety Control function"
United States
U.S. regulations define event recorders as follows: (CFR 49 Ch II 229.5):
"(g) Event recorder means a device, designed to resist tampering, that monitors and records data on train speed, direction of motion, time, distance, throttle position, brake applications and operations (including train brake, independent brake, and, if so equipped, dynamic brake applications and operations) and, where the locomotive is so equipped, cab signal aspect(s), over the most recent 48 hours of operation of the electrical system of the locomotive on which it is installed. A device, designed to resist tampering, that monitors and records the specified data."
The Federal Railroad Administrations (FRA) "Final Rule 49 CFR Part 229", (revised June 30, 2005) requires that event recorders be fitted to the leading locomotives of all US, Canadian and Mexican trains operating above on the US rail network including all freight, passenger and commuter rail locomotives but does not apply to transit running on its own dedicated tracks.
The new ruling applies to locomotives either ordered before Oct 1, 2006 or placed in service after Oct 1, 2009 and included:
Improved crash worthiness by means of a "hardened" memory module able to withstand:
Fire resistance of 750 °C for 1 hour, this test simulates the temperature of burning diesel fuel
Impact shock of 55 g 100ms
Static crush of 110 kN for 5 minutes, this test simulates a locomotive derailment and blunt object impact
Fluid immersion in Diesel, water, salt water or lube oils for 2 days
Hydrostatic pressure equivalent to immersion to a depth of 15 m in water for 2 days
Recording of additional information to enhance the quality of information available for post-accident investigations including the following "safety-critical" signals:
Speed
Direction of travel (Forward or Reverse)
Time
Distance
Throttle position
Operation of brakes
Status of Headlights and Marker Lights (On or Off)
Operation of Horn
Status of Cab signals
Store the last 48 hours of safety-critical train data. This is to prevent over-writing of the crash data if the loco is used for the subsequent "clean-up" of the crash scene.
The phasing out of the old magnetic tape models over a four-year period due to their vulnerability to data loss in the event of a crash.
United Kingdom and Ireland
All trains operating on Network Rail controlled infrastructure are required to be fitted with an event recorder complying with RIS-2472-RST-Iss-1, the standard also cross references with BS EN 62625-1:2013. Ireland has also adopted this regulation. RSSB (Rail Safety and Standards Board) is responsible for event recorder standards in the UK.
Crash protection requirements:
Fire resistance of 700 °C for 5 minutes
Impact shock of 100 g, three times on each of its six sides
Static crush of 20 kN for 1 minute, to all edges and faces
Fluid immersion in water, AFFF or R134A for 1 hour
Magnetic field produced by a current pulse of 0 to 64 kA, rising at 107 A/s, at a distance of 1 metre
The UK approach is similar to US requirements, but the list of required signals is more comprehensive. This reflects, in part, the prevalence of passenger trains and the inevitable possibility of incidents involving access doors.
Signals to be recorded include:
Brake demand including operation of all Brake Controls and other brake activations
Power notch
Wheel speed
Speedometer, both signal sent to speedometer and indication displayed to driver
Automatic Warning System (AWS) operation
Driver reminder appliance (DRA) operation
Vigilance Operation
Passenger Emergency Systems (PES)
Override of any Safety System
Horn
Door signals
Door inter-lock
Wheel slide protection (WSP)
Tilt, if fitted
Speed supervision & Control, if fitted
Switzerland
Speed recording equipment has been used by Swiss Federal Railways for many years.
See also
Black box (disambiguation)
Tachograph - largely defunct, used on locomotives and automobiles
Flight recorder, Flight data recorder and Cockpit voice recorder - used on aircraft
Event Data Recorder - used on automobiles
Voyage Data Recorder - used on ships
Data logger
References
Locomotive parts
Recording devices | Train event recorder | [
"Technology"
] | 1,630 | [
"Recording devices"
] |
5,425,217 | https://en.wikipedia.org/wiki/Full%20state%20feedback | Full state feedback (FSF), or pole placement, is a method employed in feedback control system theory to place the closed-loop poles of a plant in predetermined locations in the s-plane. Placing poles is desirable because the location of the poles corresponds directly to the eigenvalues of the system, which control the characteristics of the response of the system. The system must be considered controllable in order to implement this method.
Principle
If the closed-loop dynamics can be represented by the state space equation (see State space (controls))
with output equation
then the poles of the system transfer function are the roots of the characteristic equation given by
Full state feedback is utilized by commanding the input vector . Consider an input proportional (in the matrix sense) to the state vector,
.
Substituting into the state space equations above, we have
The poles of the FSF system are given by the characteristic equation of the matrix , . Comparing the terms of this equation with those of the desired characteristic equation yields the values of the feedback matrix which force the closed-loop eigenvalues to the pole locations specified by the desired characteristic equation.
Example of FSF
Consider a system given by the following state space equations:
The uncontrolled system has open-loop poles at and . These poles are the eigenvalues of the matrix and they are the roots of . Suppose, for considerations of the response, we wish the controlled system eigenvalues to be located at and , which are not the poles we currently have. The desired characteristic equation is then , from .
Following the procedure given above, the FSF controlled system characteristic equation is
where
Upon setting this characteristic equation equal to the desired characteristic equation, we find
.
Therefore, setting forces the closed-loop poles to the desired locations, affecting the response as desired.
This only works for Single-Input systems. Multiple input systems will have a matrix that is not unique. Choosing, therefore, the best values is not trivial. A linear-quadratic regulator might be used for such applications.
See also
Pole splitting
Step response
Ackermann's Formula
Linear-quadratic regulator
References
External links
Mathematica function to compute the state feedback gains
Control theory
Feedback | Full state feedback | [
"Mathematics"
] | 449 | [
"Applied mathematics",
"Control theory",
"Dynamical systems"
] |
5,426,393 | https://en.wikipedia.org/wiki/Advection%20upstream%20splitting%20method | The Advection Upstream Splitting Method (AUSM) is a numerical method used to solve the advection equation in computational fluid dynamics. It is particularly useful for simulating compressible flows with shocks and discontinuities.
The AUSM is developed as a numerical inviscid flux function for solving a general system of conservation equations. It is based on the upwind concept and was motivated to provide an alternative approach to other upwind methods, such as the Godunov method, flux difference splitting methods by Roe, and Solomon and Osher, flux vector splitting methods by Van Leer, and Steger and Warming.
The AUSM first recognizes that the inviscid flux consist of two physically distinct parts, i.e., convective and pressure fluxes. The former is associated with the flow (advection) speed, while the latter with the acoustic speed; or respectively classified as the linear and nonlinear fields. Currently, the convective and pressure fluxes are formulated using the eigenvalues of the flux Jacobian matrices. The method was originally proposed by Liou and Steffen for the typical compressible aerodynamic flows, and later substantially improved in to yield a more accurate and robust version. To extend its capabilities, it has been further developed in for all speed-regimes and multiphase flow. Its variants have also been proposed.
Features
The Advection Upstream Splitting Method has many features. The main features are:
accurate capturing of shock and contact discontinuities
entropy-satisfying solution
positivity-preserving solution
algorithmic simplicity (not requiring explicit eigen-structure of the flux Jacobian matrices) and straightforward extension to additional conservation laws
free of “carbuncle” phenomena
uniform accuracy and convergence rate for all Mach numbers.
Since the method does not specifically require eigenvectors, it is especially attractive for the system whose eigen-structure is not known explicitly, as the case of two-fluid equations for multiphase flow.
Applications
The AUSM has been employed to solve a wide range of problems, low-Mach to hypersonic aerodynamics, large eddy simulation and aero-acoustics, direct numerical simulation, multiphase flow, galactic relativistic flow etc.
See also
Euler equations
Finite volume method
Flux limiter
Godunov's theorem
High resolution scheme
Numerical method of lines
Sergei K. Godunov
Total variation diminishing
References
Computational fluid dynamics
Numerical differential equations | Advection upstream splitting method | [
"Physics",
"Chemistry"
] | 498 | [
"Computational fluid dynamics",
"Fluid dynamics",
"Computational physics"
] |
5,426,467 | https://en.wikipedia.org/wiki/Drive%20mapping | Drive mapping is how MS-DOS and Microsoft Windows associate a local drive letter (A-Z) with a shared storage area to another computer (often referred as a File Server) over a network. After a drive has been mapped, a software application on a client's computer can read and write files from the shared storage area by accessing that drive, just as if that drive represented a local physical hard disk drive.
Drive mapping
Mapped drives are hard drives (even if located on a virtual or cloud computing system, or network drives) which are always represented by names, letter(s), or number(s) and they are often followed by additional strings of data, directory tree branches, or alternate level(s) separated by a "\" symbol. Drive mapping is used to locate directories, files or objects, and programs or apps, and is needed by end users, administrators, and various other operators or groups.
Mapped drives are usually assigned a letter of the alphabet after the first few taken, such as A:\, B:\ (both of which were historically removable flexible magnetic media drives), C:\ (usually the first or only installed hard disk), and D:\ (which was often an optical drive unit). Then, with the drive and/or directory (letters, symbols, numbers, names) mapped, they can be entered into the necessary address bar/location(s) and displayed as in the following:
Example 1:
C:\level\next level\following level
or
C:\BOI60471CL\Shared Documents\Multi-Media Dept
The preceding location may reach something like a company's multi-media department's database, which logically is represented with the entire string "C:\BDB60471CL\Shared Documents\Multi-Media Dept".
Mapping a drive can be complicated for a complex system. Network mapped drives (on LANs or WANs) are available only when the host computer (File Server) is also available (i.e. online): it is a requirement for use of drives on a host. All data on various mapped drives will have certain permissions set (most newer systems) and the user will need the particular security authorizations to access it.
Drive mapping over LAN usually uses the SMB protocol on Windows or NFS protocol on UNIX/Linux (however UNIX/Linux do not map devices to drive letters as MS-DOS and Windows do). Drive mapping over the Internet usually uses the WebDAV protocol. WebDAV Drive mapping is supported on Windows, Mac, and Linux.
See also
Mount (computing)
Drive letter assignment
SUBST – a command on the DOS, IBM OS/2 and Microsoft Windows operating systems used for substituting paths on physical and logical drives as virtual drives
Disk formatting
References
Windows architecture
Computer peripherals
Network file systems | Drive mapping | [
"Technology"
] | 583 | [
"Computer peripherals",
"Computing stubs",
"Components"
] |
5,426,470 | https://en.wikipedia.org/wiki/SMS%20gateway | An SMS gateway or MMS gateway allows a computer (also known as a Server) to send or receive text messages in the form of Short Message Service (SMS) or Multimedia Messaging Service (MMS) transmissions between local and/or international telecommunications networks. In most cases, SMS and MMS are eventually routed to a mobile phone through a wireless carrier. SMS gateways are commonly used as a method for person-to-person to device-to-person (also known as application-to-person) communications. Many SMS gateways support content and media conversions from email, push, voice, and other formats.
Gateway types
Several mobile telephone network operators have true fixed-wire SMS services. These are based on extensions to the European Telecommunications Standards Institute (ETSI) Global System for Mobile Communications (GSM) SMS standards and allow messaging between any mix of fixed and mobile equipment. These use frequency-shift keying to transfer the message between the terminal and the Short Message Service Center (SMSC). Terminals are usually based on Digital Enhanced Cordless Telecommunications (DECT), but wired handsets and wired text-only (no voice) devices exist. Messages are received by the terminal recognising that the Caller ID is that of the SMSC and going off-hook silently to receive the message.
Implementations
GSM gateway appliance
A direct-to-mobile gateway is a device that has built-in wireless GSM connectivity. It allows SMS text messages to be sent and/or received by email, from Web pages or from other software applications by acquiring a unique identifier from the mobile phone's Subscriber Identity Module, or "SIM card". Direct-to-mobile gateways are different from SMS aggregators because they are installed on an organization's own network and connect to a local mobile network.
The connection to the mobile network is made by acquiring a SIM card number from the mobile operator and installing it in the gateway. Typically, direct-to-mobile gateway appliances are used for hundreds to thousands of text messages per month. More modern appliances now offer the capability of sending up to 100,000 messages each day. Several vendors that have historically provided GSM Gateway equipment for voice also have SMS capability. Some are more primitive than others. The more capable devices are designed with SIM management to regulate the number of SMS messages per SIM, ODBC to connect to a database, and HTTP interfaces to interact with third-party applications.
Regulation
GSM gateway equipment is covered by the Wireless Telegraphy Act in the UK and can legally be used by any business to send SMS to their own customers or prospects when using their own gateway equipment. In Canada, SMS gateway providers are regulated by the Canadian Wireless Telecommunications Association (CWTA/txt.ca).
In India, it is regulated by the Telecom Regulatory Authority of India (TRAI).
In Pakistan, it is regulated by the Pakistan Telecommunication Authority(PTA).
Direct-to-SMSC
A direct-to-short message service centre (SMSC) gateway is a software application, or a component within a software application, that connects directly to a mobile operator's SMSC via the Internet or direct leased line connections. The Short Message Peer-to-Peer (SMPP) protocol is typically used to convey SMS between an application and the SMSC. Direct-to-SMSC gateways are used by SMS aggregators to provide SMS services to their clients and large businesses who can justify such use. They are typically employed for high volume messaging and require a contract directly with a mobile operator.
Direct-to-SMS gateway
An SMS gateway typically sits between the end-user who needs to send/receive SMS and a mobile network's SMSC. Such gateways provide their customers with a choice of protocols, including HTTP, SMTP, Short Message Peer-to-Peer and Web Services. Providers of SMS gateway services include SMS aggregators and mobile operators. SMS gateways are also available as part of messaging services such as AOL, ICQ and others.
In order to send/receive messages with mobile subscribers, an SMS gateway connects with (i) mobile network SMSCs and/or (ii) other SMS gateways. It is, therefore, possible that an SMS gateway has a combination of connections with mobile network SMSCs and connections with other SMS gateways in order to provide its services. However, there is an increasing potential for delivery problems with SMS with increasing number of SMS gateways in the delivery chain.
Email clients
Text messages can be sent from a personal computer to mobile devices via an SMS gateway or Multimedia Messaging Service (MMS) gateway, using the most popular email client programs, such as Outlook, Thunderbird, and so on. The messages must be sent in ASCII "text-only" mode. If they are sent in HTML mode or using non-ASCII characters, they will most likely appear as nonsense on the recipient's mobile telephone.
Before the message can be sent, one must determine the domain of the mobile carrier's SMS gateway. For example, if one wants to send a message to a mobile telephone in the United States serviced by AT&T, and the telephone number is +1 415-123-4567, the email would be addressed as
4151234567@txt.att.net
To determine the SMS gateway domain, e.g., txt.att.net, may require research - but most users know who their carrier is. The telephone number in this example for a US number is expressed as ten (10) digits, without the country code (1) and without dashes or other separator characters when composing the email address. The country code is not needed, as the 10-digit telephone number, together with the email domain, are sufficient to send the email from any location in the world.
It is useful to perform a character count before sending the message to ensure that it is within the 160-character limit. If it exceeds the limit, the SMS gateway should break the message into a set of consecutive 160-character, or shorter, messages to the mobile equipment, although breaks may occur in the middle of words.
A message sent with an email client can be simultaneously addressed to multiple mobile telephones - just as text messages sent in the usual manner between mobile telephones can be sent to multiple recipients.
SMS gateway domains for other carriers (US-based):
SMS gateway domains for Canadian carriers:
SMS gateway features
There are several applications for SMS gateways, including:
Bulk/mass SMS messaging communications commonly used for customer care to marketing campaigns
Two-way SMS messaging, designed for the exchange of messages from clients to a customer portal
To enable the development of an SMS widget for newsletters and updates
API allowing systems to integrate with 3rd party systems including common CRM, e-commerce, ERP, and internal platforms
For multi-factor authentication or two-factor authentication using SMS as a channel for delivering one-time-passwords (OTPs)
See also
Kannel (telecommunications)
Videoconferencing
Voice over IP
References
Mobile telecommunications
Text messaging | SMS gateway | [
"Technology"
] | 1,447 | [
"Mobile telecommunications"
] |
5,427,265 | https://en.wikipedia.org/wiki/ISIS/Draw | ISIS/Draw was a chemical structure drawing program developed by MDL Information Systems. It introduced a number of file formats for the storage of chemical information that have become industry standards.
History
Molecular Design Limited (MDL) was founded by Stuart Marson and W. Todd Wipke in 1978, following the latter's experience with E. J. Corey in developing software for planning organic syntheses. The company developed software to store and search chemical structures in large databases under the brand name MACCS (Molecular ACCess System), which was targeted at pharmaceutical and agrochemical companies. MDL offered their ISIS (Integrated Scientific Information System) products including ISIS/Draw as components of the MACCS system, specifically to allow chemists to use a graphical interface to register new compounds into corporate databases and to search these databases by structure or part-structure. They also introduced ISIS/Base, a chemical database program suited to the storage of relatively small numbers of structures with associated data for personal use independently of corporate systems. ISIS/Draw structures could be incorporated into other documents, for example using the word processor software which was becoming available in the 1980s, hence providing full electronic publishing for chemists. MDL released many versions of the software and made ISIS/Draw freely available for non-commercial use: version 2.5 was available to run on Windows 98.
By 2007, MDL (then owned by Reed Elsevier) merged with Symyx Technologies, which in turn was acquired by Accelrys in 2010 and is now owned by Dassault Systèmes. The software is now branded as BIOVIA Draw.
File formats
MDL introduced specifications for chemical file formats, including the molfile (.mol), and structure/data file (.sdf) which were subsequently placed in the public domain and have become standards for representing structures in 2-D drawings and for transferring such information with associated data, for example identifiers, chemical names and substance properties.
Many public databases implemented these standards and ChemSpider, for example, allows users to download molfiles for the structures it holds. ISIS/Draw retained its own proprietary file formats with the extension .skc (sketch file) and .rxn (for reactions) and because of its role in preparing database queries it supported a variety of special atom and bond types used for substructure searching, such as wildcard atoms, aromatic bonds, ring bonds, and the atom mapping required for reaction searches.
Program features
While ISIS/Draw was mainly a 2D drawing program, it had some 3D rotation features and could interface with Rasmol for 3D visualization and rendering. ISIS/Draw also included structure and reaction validation features and could calculate elementary properties such as formula and molecular weight. It had an "AutoNom" add-in that allowed the creation of IUPAC names for valid structures and could use a special "pseudoatom" to generate amino-acid sequences for proteins.
One important feature of the MACCS system and ISIS/Draw was that it had comprehensive facilities, using hatched and wedged bonds, to represent relative or absolute stereochemistry and chirality and to recognise cis–trans isomerism in double bonds. In this respect it was superior to Wiswesser line notation which had hitherto been used to create searchable databases. Likewise, while SMILES notation can handle stereochemistry in some implementations it is more difficult for non-specialists to encode their structures in that way than by drawing them.
Current implementation
The current (2020) implementation of the software is called BIOVIA Draw and has several new features such as support for reading and writing International Chemical Identifiers (InChi) and converting IUPAC names into structure drawings. It is freely available for academic and non-commercial use.
See also
MDL Chime
Molecule editor
References
Further reading
Chemistry software | ISIS/Draw | [
"Chemistry"
] | 783 | [
"Chemistry software",
"nan"
] |
5,427,586 | https://en.wikipedia.org/wiki/Strahler%20number | In mathematics, the Strahler number or Horton–Strahler number of a mathematical tree is a numerical measure of its branching complexity.
These numbers were first developed in hydrology, as a way of measuring the complexity of rivers and streams, by and . In this application, they are referred to as the Strahler stream order and are used to define stream size based on a hierarchy of tributaries.
The same numbers also arise in the analysis of L-systems and of hierarchical biological structures such as (biological) trees and animal respiratory and circulatory systems, in register allocation for compilation of high-level programming languages and in the analysis of social networks.
Definition
All trees in this context are directed graphs, oriented from the root towards the leaves; in other words, they are arborescences. The degree of a node in a tree is just its number of children. One may assign a Strahler number to all nodes of a tree, in bottom-up order, as follows:
If the node is a leaf (has no children), its Strahler number is one.
If the node has one child with Strahler number i, and all other children have Strahler numbers less than i, then the Strahler number of the node is i again.
If the node has two or more children with Strahler number i, and no children with greater number, then the Strahler number of the node is i + 1.
The Strahler number of a tree is the number of its root node.
Algorithmically, these numbers may be assigned by performing a depth-first search and assigning each node's number in postorder.
The same numbers may also be generated via a pruning process in which the tree is simplified in a sequence of stages, where in each stage one removes all leaf nodes and all of the paths of degree-one nodes leading to leaves: the Strahler number of a node is the stage at which it would be removed by this process, and the Strahler number of a tree is the number of stages required to remove all of its nodes. Another equivalent definition of the Strahler number of a tree is that it is the height of the largest complete binary tree that can be homeomorphically embedded into the given tree; the Strahler number of a node in a tree is similarly the height of the largest complete binary tree that can be embedded below that node.
Any node with Strahler number i must have at least two descendants with Strahler number i − 1, at least four descendants with Strahler number i − 2, etc., and at least 2i − 1 leaf descendants. Therefore, in a tree with n nodes, the largest possible Strahler number is log2 n + 1. However, unless the tree forms a complete binary tree its Strahler number will be less than this bound. In an n-node binary tree, chosen uniformly at random among all possible binary trees, the expected index of the root is with high probability very close to log4 n.
Applications
River networks
In the application of the Strahler stream order to hydrology, each segment of a stream or river within a river network is treated as a node in a tree, with the next segment downstream as its parent. When two first-order streams come together, they form a second-order stream. When two second-order streams come together, they form a third-order stream. Streams of lower order joining a higher order stream do not change the order of the higher stream. Thus, if a first-order stream joins a second-order stream, it remains a second-order stream. It is not until a second-order stream combines with another second-order stream that it becomes a third-order stream. As with mathematical trees, a segment with index i must be fed by at least 2i − 1 different tributaries of index 1. Shreve noted that Horton's and Strahler's Laws should be expected from any topologically random distribution. A later review of the relationships confirmed this argument, establishing that, from the properties the laws describe, no conclusion can be drawn to explain the structure or origin of the stream network.
To qualify as a stream a hydrological feature must be either recurring or perennial. Recurring (or "intermittent") streams have water in the channel for at least part of the year. The index of a stream or river may range from 1 (a stream with no tributaries) to 12 (globally the most powerful river, the Amazon, at its mouth). The Ohio River is of order eight and the Mississippi River is of order 10. Estimates are that 80% of the streams on the planet are first to third order headwater streams.
If the bifurcation ratio of a river network is high, then there is a higher chance of flooding. There would also be a lower time of concentration. The bifurcation ratio can also show which parts of a drainage basin are more likely to flood, comparatively, by looking at the separate ratios. Most British rivers have a bifurcation ratio of between 3 and 5.
describe how to compute Strahler stream order values in a GIS application. This algorithm is implemented by RivEX, an ESRI ArcGIS Pro 3.3.x tool. The input to their algorithm is a network of the centre lines of the bodies of water, represented as arcs (or edges) joined at nodes. Lake boundaries and river banks should not be used as arcs, as these will generally form a non-tree network with an incorrect topology.
Alternative stream ordering systems have been developed by Shreve and Hodgkinson et al. A statistical comparison of Strahler and Shreve systems, together with an analysis of stream/link lengths, is given by Smart.
Other hierarchical systems
The Strahler numbering may be applied in the statistical analysis of any hierarchical system, not just to rivers.
describe an application of the Horton–Strahler index in the analysis of social networks.
applied a variant of Strahler numbering (starting with zero at the leaves instead of one), which they called tree-rank, to the analysis of L-systems.
Strahler numbering has also been applied to biological hierarchies such as the branching structures of trees and of animal respiratory and circulatory systems.
Register allocation
When translating a high-level programming language to assembly language the minimum number of registers required to evaluate an expression tree is exactly its Strahler number. In this context, the Strahler number may also be called the register number.
For expression trees that require more registers than are available, the Sethi–Ullman algorithm may be used to translate an expression tree into a sequence of machine instructions that uses the registers as efficiently as possible, minimizing the number of times intermediate values are spilled from registers to main memory and the total number of instructions in the resulting compiled code.
Related parameters
Bifurcation ratio
Associated with the Strahler numbers of a tree are bifurcation ratios, numbers describing how close to balanced a tree is. For each order i in a hierarchy, the ith bifurcation ratio is
where ni denotes the number of nodes with order i.
The bifurcation ratio of an overall hierarchy may be taken by averaging the bifurcation ratios at different orders. In a complete binary tree, the bifurcation ratio will be 2, while other trees will have larger bifurcation ratios. It is a dimensionless number.
Pathwidth
The pathwidth of an arbitrary undirected graph G may be defined as the smallest number w such that there exists an interval graph H containing G as a subgraph, with the largest clique in H having w + 1 vertices. For trees (viewed as undirected graphs by forgetting their orientation and root) the pathwidth differs from the Strahler number, but is closely related to it: in a tree with pathwidth w and Strahler number s, these two numbers are related by the inequalities
w ≤ s ≤ 2w + 2.
The ability to handle graphs with cycles and not just trees gives pathwidth extra versatility compared to the Strahler number.
However, unlike the Strahler number, the pathwidth is defined only for the whole graph, and not separately for each node in the graph.
See also
Main stem of a river, typically found by following the branch with the highest Strahler number
Pfafstetter Coding System
Notes
References
.
.
.
.
.
.
.
.
.
.
.
.
.
Hydrology
Geomorphology
Physical geography
Trees (graph theory)
Graph invariants | Strahler number | [
"Chemistry",
"Mathematics",
"Engineering",
"Environmental_science"
] | 1,773 | [
"Hydrology",
"Graph theory",
"Graph invariants",
"Mathematical relations",
"Environmental engineering"
] |
5,427,709 | https://en.wikipedia.org/wiki/Acarinarium | An acarinarium is a specialized anatomical structure which is evolved to facilitate the retention of mites on the body of an organism, typically a bee or a wasp. The term was introduced by Walter Karl Johann Roepke.
Evolution
The acarinarium has evolved to enhance the mutualistic relationship between the mites and the host organism. There are numerous cases where mites are phoretic on organisms that benefit from the mites' presence; cases where the host's body has changed over evolutionary time to accommodate the mites are far less common. The best-known examples are among the Apocritan Hymenoptera, in which the hosts are typically nest-making species, and it appears that the mites feed on fungi in the host nests (thus keeping away the fungi from host's offspring or their provisions), or possibly other parasites or mites whose presence in the nest is detrimental to the hosts. It is especially telling that nearly all the examples involve only the females of the host species, as it is the females that build and provision the nests. Fossil evidence of halictid bees with an acarinarium is found in the early Miocene extinct genus Oligochlora from Dominican amber deposits on Hispaniola.
The presence or absence of this structure has been used as a taxonomic character.
Variations
Several examples can be found among the bees, and in most such cases, only the females possess acarinaria:
Various forms of acarinaria have evolved within different lineages of carpenter bees, in the Old World subgenera Koptortosoma and Mesotrichia - in some cases, the entire anterior portion of the metasoma is hollowed out into an enormous internal chamber, entered through a small opening on the face of the first metasomal tergite, in which the mites can travel. Some species in these groups also have supplementary acarinaria on the mesosoma in addition to the metasomal chamber.
The augochlorine halictid genus Thectochlora is characterized by a dense brush of hairs just in front of the anterior face of the first metasomal tergite (the same effective location as in carpenter bees), which sets off a "pouchlike" space in which the mites are carried.
In the nominate subgenus of the halictine genus Lasioglossum, many species have the anterior face of the first metasomal tergite modified by the elimination of the central setae, forming a central glabrous area, around which there is a fringe of appressed hairs, and mites cling to this area. Species without this modification rarely if ever have mites in this region, while those with the glabrous area almost never lack mites, so despite its simple nature it does indeed appear to function as an acarinarium. In some cases, sister species may differ in this feature, one having an acarinarium, and one lacking it, suggesting that the trait can be lost and possibly regained.
Other examples include:
In the potter wasp genus Parancistrocerus, the base of the second metasomal tergite is concave, and covered by the posterior lip of the first metasomal tergite, and mites are carried in the concavity. This structure appears the same in both males and females, though it is difficult to assess whether both sexes carry mites with equal frequency.
References
External links
Bees and mites
Insect anatomy
Acari
Symbiosis | Acarinarium | [
"Biology"
] | 717 | [
"Biological interactions",
"Behavior",
"Symbiosis"
] |
5,427,787 | https://en.wikipedia.org/wiki/List%20of%20Guggenheim%20Fellowships%20awarded%20in%201941 | Eighty-five Guggenheim Fellowships were awarded in 1941.
1941 U.S. and Canadian Fellows
1941 Latin American and Caribbean Fellows
See also
Guggenheim Fellowship
List of Guggenheim Fellowships awarded in 1940
List of Guggenheim Fellowships awarded in 1942
References
1941
Guggenheim
Guggenheim | List of Guggenheim Fellowships awarded in 1941 | [
"Biology"
] | 48 | [
"Fungi",
"Parasites of fungi"
] |
5,428,000 | https://en.wikipedia.org/wiki/Microsoft%20Voice%20Command | Microsoft Voice Command is an application which can control Windows Mobile devices by voice. The first version was announced in November 2003 and it was supported in the United Kingdom, United States, France, and Germany.
Windows Mobile 6.5 had Microsoft TellMe integration, software created by a company Microsoft had recently acquired. This feature was later implemented in Windows Phone as a part of Bing Mobile.
See also
Speech recognition
Speech synthesis
Voice control
Microsoft Cortana
References
External links
How To Use Speech Recognition in Windows XP
Microsoft speech page
Voice Command
Pocket PC software
Windows Mobile Standard software
Speech recognition software
2003 software | Microsoft Voice Command | [
"Technology"
] | 118 | [
"Mobile software stubs",
"Mobile technology stubs"
] |
5,429,905 | https://en.wikipedia.org/wiki/Small-world%20routing | In network theory, small-world routing refers to routing methods for small-world networks. Networks of this type are peculiar in that relatively short paths exist between any two nodes. Determining these paths, however, can be a difficult problem from the perspective of an individual routing node in the network if no further information is known about the network as a whole.
Greedy routing
Nearly every solution to the problem of routing in small world involves the application of greedy routing. This sort of routing depends on a relative reference point by which any node in the path can choose the next node it believes is closest to the destination. That is, there must be something to be greedy about. For example, this could be geographic location, IP address, etc. In the case of Milgram's original small-world experiment, participants knew the location and occupation of the final recipient and could therefore forward messages based on those parameters.
Constructing a reference base
Greedy routing will not readily work when there is no obvious reference base. This can occur, for example, in overlay networks where information about the destination's location in the underlying network is not available. Friend-to-friend networks are a particular example of this problem. In such networks, trust is ensured by the fact that you only know underlying information about nodes with whom you are already a neighbor.
One solution in this case, is to impose some sort of artificial addressing on the nodes in such a way that this addressing can be effectively used by greedy routing methods. A 2005 paper by a developer of the Freenet Project discusses how this can be accomplished in friend to friend networks. Given the assumption that these networks exhibit small world properties, often as the result of real-world or acquaintance relationships, it should be possible to recover an embedded Kleinberg small-world graph. This is accomplished by selecting random pairs of nodes and potentially swapping them based on an objective function that minimizes the product of all the distances between any given node and its neighbors.
An important problem involved with this solution is the possibility of local minima. This can occur if nodes are in a situation that is optimal only considering a local neighborhood, while ignoring the possibility of a higher optimality resulting from swaps with distant nodes. In the above paper, the authors proposed a simulated annealing method where less-than-optimal swaps were made with a small probability. This probability was proportional to the value of making the switches. Another possible metaheuristic optimization method is a tabu search, which adds a memory to the swap decision. In its most simplistic form, a limited history of past swaps is remembered so that they will be excluded from the list of possible swapping nodes.
This method for constructing a reference base can also be adapted to distributed settings, where decisions can only be made at the level of individual nodes who have no knowledge of the overall network. It turns out that the only modification necessary is in the method for selecting pairs of random nodes. In a distributed setting, this is done by having each node periodically send out a random walker terminating at a node to be considered for swapping.
The Kleinberg model
The Kleinberg model of a network is effective at demonstrating the effectiveness of greedy small world routing. The model uses an n x n grid of nodes to represent a network, where each node is connected with an undirected edge to its neighbors. To give it the "small world" effect, a number of long range edges are added to the network that tend to favor nodes closer in distance rather than farther. When adding edges, the probability of connecting some random vertex to another random vertex w is proportional to , where is the clustering exponent.
Greedy routing in the Kleinberg model
It is easy to see that a greedy algorithm, without using the long range edges, can navigate from random vertices on the grid in time. By following the guaranteed connections to our neighbors, we can move one unit at a time in the direction of our destination. This is also the case when the clustering component is large and the "long range" edges end up staying very close; we simply do not take advantage of the weaker ties in this model. When , the long range edges are uniformly connected at random which means the long range edges are "too random" to be used efficiently for decentralized search. Kleinberg has shown that the optimal clustering coefficient for this model is , or an inverse square distribution.
To reason why this is the case, if a circle of radius r is drawn around the initial node it will have nodal density where n is the number of nodes in the circular area. As this circle gets expanded further out, the number of nodes in the given area increases proportional to as the probability of having a random link with any node remains proportional , meaning the probability of the original node having a weak tie with any node a given distance away is effectively independent of distance. Therefore, it is concluded that with , long-range edges are evenly distributed over all distances, which is effective for letting us funnel to our final destination.
Some structured Peer-to-peer systems based on DHTs often are implementing variants of Kleinberg's Small-World topology to enable efficient routing within Peer-to-peer network with limited node degrees.
See also
References
Network theory | Small-world routing | [
"Mathematics"
] | 1,063 | [
"Network theory",
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5,430,713 | https://en.wikipedia.org/wiki/Suntech%20Power | Suntech Power Holdings Co., Ltd. () is a Chinese producer of solar panels, with of annual production capacity by the end of 2011. It is headquartered in Wuxi, Jiangsu. Shunfeng International Clean Energy Limited, a HKSE listed renewable energy investment and Independent Power Producer company, acquired Suntech in 2014 following Suntech's bankruptcy in 2013. With offices or production facilities in every major market, Suntech has delivered more than 13,000,000 solar panels to thousands of companies in more than 80 countries around the world. As the center for the company's global operations, Suntech headquarters, in Wuxi, China, features the world's largest building integrated solar facade.
Suntech's fortunes have declined significantly since its peak in 2008, due to a glut in the market for solar products and problems with its investments. In March 2013 it announced a US$541 million bond payment default, becoming the first company from mainland China to default on its US bonds.
Chinese banks subsequently filed to place Suntech's main unit, Wuxi Suntech Power Holdings Co., Ltd., into insolvency. The company's American Depository Receipts were subsequently delisted from the New York Stock Exchange and placed on the over the counter (OTC) exchange.
Founder
Dr Shi Zhengrong (born c. 1963) was the founder of Suntech Power and, until 2013, its chairman and chief executive officer.
He is a graduate of the University of New South Wales' (UNSW) School of Photovoltaic and Renewable Energy Engineering. At UNSW, Dr. Shi studied under Professor Martin Green and met Stuart Wenham, later to be Suntech's Chief Technology Officer.
In 2007, Dr. Shi was named one of Time Magazine's Heroes of the Environment and referred to as the world's first 'green billionaire'. Dr. Shi was honored in January 2010 as a finalist for the Zayed Future Energy Prize. Dr. Shi was also appointed Visiting Professor at UNSW.
Global operations
Suntech Power has representative offices in China, Australia, the United States, Switzerland, Spain, Italy, Germany, Japan, and Dubai, as well as production facilities in Wuxi, Luoyang, Qinghai, Shanghai, Germany, Japan, and Goodyear, Arizona.
Suntech America was based in San Francisco, California, and had plans to start a production facility in Phoenix, Arizona in 2010. In 2009, Suntech had executives of their US operations in top posts in American solar panel industry groups.
Installations
Suntech Power has supplied or installed solar modules for numerous solar power plants and systems around the world. Notable installations include:
Clif Bar Headquarters
The Wharf, home of the Sydney Theatre Company (Sydney, Australia)
Alamosa Power Plant (Colorado, US)
Arizona State University (Arizona, US)
Beijing National Stadium (Beijing, China)
Elecnor Power Plant (Trujillo, Spain)
Masdar City Solar Farm (Abu Dhabi, UAE)
Nellis Air Force Base (Nevada, US)
Expo 2010 Shanghai (Shanghai, China)
Ketura Sun (Kibbutz Ketura, Israel)
The company's Suntech Energy Solutions division completed Google's 1.6 MW solar installation in June 2007.
Suntech Power joined with Israeli company Solarit Doral to build a 50 kW rooftop project in the Israeli settlement of Katzrin in the Golan Heights, which was connected to the electricity grid in December 2008.
Suntech panels were used on the Ketura Sun field, the first commercial solar field in Israel. The field was developed by the Arava Power Company.
In 2010, Suntech topped the solar panel shipment with 1.49 GW shipment volume, according to PVinsights. Suntech targets to ship over 2 GW in 2011; however, free price fall for solar components in 2011 made this more difficult to achieve. During the downturn of solar panel price, Chinese companies showed their ability to compete in cost management.
On the very first day of the third quarter in 2011, SunTech announced that they would terminate their long-term wafer contract with MEMC by paying $120 million.
Market share of the top five Chinese solar companies ranked in 2011, which are Suntech, Yingli, Trina, Canadian and Jinko, made a huge advancement from 17.2% market share in 2009 to 30% market share in 2011. The five Chinese solar module companies almost doubled their totaling market share in 2.5 years and took nearly one-third of the worldwide market.
Awards
Suntech Power was recognized as the 2008 Frost & Sullivan Solar Energy Development Company of the Year. Frost & Sullivan Research Analyst Mary John commented on the recognition, "The company's pioneering success in developing energy-efficient, cost-effective and customizable building integrated photovoltaic (BIPV) systems and crystalline PV cells, and modules for solar energy conversion into electricity are highly commendable. It has gone beyond just meeting global energy needs to anticipating them as well and highly satisfied customers testify that the BIPV systems and other energy-efficient products are customized precisely to their needs."
The Andalay AC Solar PV Panel was awarded one on MSN's most brilliant products of 2009 because of innovations that advanced their ease of installation and use. Suntech Power is one of the main manufacturers of components for the Andalay Solar Panel sold by Akeena Solar (AKNS).
Financial activities
Shi founded Suntech with support from the Wuxi city government, which held a 25% stake in the company. Three local government financing vehicles and five local state-owned enterprises also invested in the company. Private and foreign investors purchased all of Suntech's previously state-held shares prior to the company's offering on the NYSE in 2005.
At the time of that offering, Suntech was funded by a consortium of private equity firms, including Actis Capital and Goldman Sachs. The consolidated private equity investment into Suntech is generally considered to be one of China's most profitable private equity investments ever, as each firm is thought to have made gains well over 10x on their original investments. The company's stock performed quite well after its first day of IPO on December 14, 2005.
After Suntech's NYSE listing, Shi became the richest person in China. Academic Lan Xiaohuan writes that Shi's wealth following the listing "acted as a strong demonstration effect and local governments across China soon began to invest in the solar industry."
GSF became biggest partner of Suntech and in 2010, almost all the international sales were through GSF. In June 2008, Suntech invested into their biggest partner, Global Solar Fund (GSF), a company investing in power plants in Spain and Italy. In May 2010, Suntech guaranteed a finance arrangement of €554.2 million provided by China Development Bank to companies related to GSF, using €560 million in German government bonds from GSF Capital as collateral. There was no issue related with transparency and GSF was wrongly blamed for failure of Suntech (evident from Earnings call, Chairman comments). However, on 30 July 2012 Suntech revealed that the bonds didn't exist, they were apparently forgeries. In the following week, Suntech shares lost 40% of their value.
Decline
Suntech announced in 2013 that it will be closing its Goodyear, Arizona, panel manufacturing plant. The reason given for the closure was the hefty tariffs imposed on Chinese solar cells by the United States International Trade Commission. Though the panels were assembled in Arizona, the cells were produced in China.
Bankruptcy
In 2013 the solar industry faced over capacity.
Suntech, defaulted on $541 million of convertible bonds in March 2013. On March 20, 2013, the main subsidiary of Suntech filed for bankruptcy in Jiangsu, China. In February 2014, Suntech filed for Chapter 15 bankruptcy in Manhattan, New York, to seek protection from U.S. creditors. A creditors’ working group led by distressed debt funds Clearwater Capital Partners LLC and Spinnaker Capital Ltd. announced in August a plan to recapitalize the solar maker, the company said in a statement.
See also
Solar power in China
References
External links
Suntech website
Companies formerly listed on the New York Stock Exchange
Photovoltaics manufacturers
Manufacturing companies of China
Companies based in Wuxi
Companies established in 2001
Solar energy in China
Chinese brands
Companies that have filed for bankruptcy in the People's Republic of China
Companies that filed for Chapter 11 bankruptcy in 2014
2001 in Wuxi | Suntech Power | [
"Engineering"
] | 1,741 | [
"Photovoltaics manufacturers",
"Engineering companies"
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5,430,925 | https://en.wikipedia.org/wiki/Sasha%20and%20Zamani | Sasha and Zamani are two aspects of time as expressed in some Eastern and Central African cultures. Sasa are spirits known by someone still alive while Zamani are spirits not known by anyone currently alive. Sasa are concerned with, and are expressed as, the present time, the recent past, and the near future while Zamani is the limitless past. Potential time is the third part of the space-time continuum in African thought. People must learn from the past to act wisely in the present to create a good future.
Description
According to James Loewen in his book Lies My Teacher Told Me: The recently departed whose time overlapped with people still here are the Sasha, the living dead. They are not wholly dead, for they live on in the memories of the living ... when the last person knowing an ancestor dies, that ancestor leaves the Sasha for the Zamani, the dead. As generalized ancestors, the Zamani are not forgotten but revered. Loewen cites and paraphrases the explanation from African Religions and Philosophy by John Mbiti. Sasha and Zamani are not stages of death. They are the two ontological stages (or dimensions) of history in Swahili culture.
In Swahili, the two time dimensions are called sasa and zamani. Both have quality and quantity. People speak of them as big, small, little, short, long, etc. in relation to a particular event. Sasha refers to the events that have just taken place or are taking place now at the moment or are just about to take place in the near future. Sasha time can extend into the future for about six months or, at the most, one year. Zamani time overlaps Sasha time to some extent in the present, but it also goes back very far into the past time. It absorbs, holds, and stores all the events that have ever occurred. It is more significant than sasha because it stretches endlessly back into the past. It includes the time of myth when all the stories of creation took place and when the great and famous heroes of the past performed their exploits (Anderson 1986, Mbiti 1994).
Zamani is not limited to what in English is called the past.… Zamani overlaps with Sasha and the two are not separable. Sasha feeds or disappears into Zamani. But before events become incorporated into the Zamani, they have to become realized or actualized within the Sasha dimension. When this has taken place, the events "move" backwards from the Sasha into the Zamani…. It is the final storehouse for all phenomena and events, the ocean of time in which everything becomes absorbed into a reality that is neither after nor before.
John S. Mbiti, African Religions and Philosophy, 2nd ed. (Oxford: Heinemann, 1990), 22.
References
Cultural aspects of death
Swahili culture
Time in religion | Sasha and Zamani | [
"Physics"
] | 589 | [
"Spacetime",
"Time in religion",
"Physical quantities",
"Time"
] |
5,431,214 | https://en.wikipedia.org/wiki/Bioclipse | The Bioclipse project is a Java-based, open-source, visual platform for chemo- and bioinformatics based on the Eclipse Rich Client Platform (RCP).
About
Biclipse gained scripting functionality in 2009, and a command line version in 2021.
Like any RCP application, Bioclipse uses a plugin architecture that inherits basic functionality and visual interfaces from Eclipse, such as help system, software updates, preferences, cross-platform deployment etc. Via its plugins, Bioclipse provides functionality for chemo- and bioinformatics, and extension points that easily can be extended by other, possibly proprietary, plugins to provide additional functionality.
Product
The first stable release of Bioclipse includes a Chemistry Development Kit (CDK) plugin to provide a chemoinformatic backend, a Jmol plugin for 3D-visualization of molecules, and a BioJava plugin for sequence analysis. Recently, the R platform, using StatET, and OpenTox were added.
Bioclipse is developed as a collaboration between the Proteochemometric Group, Dept. of Pharmaceutical Biosciences, Uppsala University, Sweden, the Christoph Steinbeck Group at the European Bioinformatics Institute, and the Analytical Chemistry Department at Leiden University, but also includes extensions developed at other academic institutes, including the Karolinska Institutet and Maastricht University. The development is backed up by the International Bioclipse Association.
Bioclipse Scripting Language
The Bioclipse Scripting Language (BSL) is a scripting environment, currently based on JavaScript and Groovy. It extends the scripting language with managers that wrap the functionality of third party libraries, as mentioned above. These scripts thus provide means to make analyses in Bioclipse sharable, for example, on MyExperiment.org. Bioclipse defines a number of core data types that managers support, allowing information to be used between these managers.
References
External links
Free bioinformatics software
Cheminformatics
Java platform software
Free chemistry software
Bioinformatics companies
Chemotherapy | Bioclipse | [
"Chemistry"
] | 446 | [
"Free chemistry software",
"Chemistry software",
"Computational chemistry",
"Cheminformatics",
"nan"
] |
5,431,341 | https://en.wikipedia.org/wiki/Audio%20over%20Ethernet | In audio and broadcast engineering, audio over Ethernet (AoE) is the use of an Ethernet-based network to distribute real-time digital audio. AoE replaces bulky snake cables or audio-specific installed low-voltage wiring with standard network structured cabling in a facility. AoE provides a reliable backbone for any audio application, such as for large-scale sound reinforcement in stadiums, airports and convention centers, multiple studios or stages.
While AoE bears a resemblance to voice over IP (VoIP) and audio over IP (AoIP), AoE is intended for high-fidelity, low-latency professional audio. Because of the fidelity and latency constraints, AoE systems generally do not utilize audio data compression. AoE systems use a much higher bit rate (typically 1 Mbit/s per channel) and much lower latency (typically less than 10 milliseconds) than VoIP. AoE requires a high-performance network. Performance requirements may be met through use of a dedicated local area network (LAN) or virtual LAN (VLAN), overprovisioning or quality of service features.
Some AoE systems use proprietary protocols (at the lower OSI layers) which create Ethernet frames that are transmitted directly onto the Ethernet (layer 2) for efficiency and reduced overhead. The word clock may be provided by broadcast packets.
Protocols
There are several different and incompatible protocols for audio over Ethernet. Protocols can be broadly categorized into layer-1, layer-2 and layer-3 systems based on the layer in the OSI model where the protocol exists.
Layer-1 protocols
Layer-1 protocols use Ethernet wiring and signaling components but do not use the Ethernet frame structure. Layer-1 protocols often use their own media access control (MAC) rather than the one native to Ethernet, which generally creates compatibility issues and thus requires a dedicated network for the protocol.
Open standards
AES50 (SuperMAC) by Klark Teknik, a point-to-point interconnect for bidirectional digital audio and sync clock
MaGIC by Gibson
Proprietary
HyperMAC, a gigabit Ethernet variant of SuperMAC
A-Net by Aviom
AudioRail
ULTRANET By Behringer
Layer-2 protocols
Layer-2 protocols encapsulate audio data in standard Ethernet packets. Most can make use of standard Ethernet hubs and switches though some require that the network (or at least a VLAN) be dedicated to the audio distribution application.
Open standards
AES51, a method of passing ATM services over Ethernet that allows AES3 audio to be carried in a similar way to AES47
Audio Video Bridging (AVB), when used with the IEEE 1722 AV Transport Protocol profile (which transports IEEE 1394/IEC 61883 (FireWire) over Ethernet frames, using IEEE 802.1AS for timing)
Proprietary
CobraNet
RAVE by QSC Audio, an implementation of CobraNet
EtherSound by Digigram
NetCIRA, a rebranded EtherSound by Fostex
REAC and RSS digital snake technology by Roland
SoundGrid by Waves Audio
dSNAKE by Allen & Heath
Layer-3 protocols
Layer-3 protocols encapsulate audio data in OSI model layer 3 (network layer) packets. By definition it does not limit the choice of protocol to be the most popular layer-3 protocol, the Internet Protocol (IP). In some implementations, the layer-3 audio data packets are further packaged inside OSI model layer-4 (transport layer) packets, most commonly User Datagram Protocol (UDP) or Real-time Transport Protocol (RTP). Use of UDP or RTP to carry audio data enables them to be distributed through standard computer routers, thus a large distribution audio network can be built economically using commercial off-the-shelf equipment.
Although IP packets can traverse the Internet, most layer-3 protocols cannot provide reliable transmission over the Internet due to the limited bandwidth, significant End-to-end delay and packet loss that can be encountered by data flow over the Internet. For similar reasons, transmission of layer-3 audio over wireless LAN are also not supported by most implementations.
Open standards
AES67
Audio Contribution over IP standardized by the European Broadcasting Union
Audio Video Bridging (AVB), when used with IEEE 1733 or AES67 (which uses standard RTP over UDP/IP, with extensions for linking IEEE 802.1AS Precision Time Protocol timing information to payload data)
NetJack, a network backend for the JACK Audio Connection Kit
Zita-njbridge, a set of clients for the JACK Audio Connection Kit
RAVENNA by ALC NetworX (uses PTPv2 timing)
Proprietary
Livewire by Axia Audio, a division of Telos Systems
Dante by Audinate (PTP version 1 timing)
Q-LAN by QSC Audio Products (PTP version 2 timing)
WheatNet-IP by Wheatstone Corporation
Similar concepts
High quality digital audio distribution was patented in 1988 by Tareq Hoque at the MIT Media Lab. The technology was licensed to several leading OEM audio and chip manufacturers that were further developed into commercial products.
RockNet by Riedel Communications, uses Cat-5 cabling. Hydra2 by Calrec uses Cat-5e cabling or fiber through SFP transceivers.
MADI uses 75-ohm coaxial cable with BNC connectors or optical fibre to carry up to 64 channels of digital audio in a point-to-point connection. It is most similar in design to AES3, which can carry only two channels.
AES47 provides audio networking by passing AES3 audio transport over an ATM network using structured network cabling (both copper and fibre). This was used extensively by contractors supplying the BBC's wide area real-time audio connectivity around the UK.
Audio over IP differs in that it works at a higher layer, encapsulated within Internet Protocol. Some of these systems are usable on the Internet, but may not be as instantaneous, and are only as reliable as the network route — such as the path from a remote broadcast back to the main studio, or the studio/transmitter link (STL), the most critical part of the airchain. This is similar to VoIP, however AoIP is comparable to AoE for a small number of channels, which are usually also data-compressed. Reliability for permanent STL uses comes from the use of a virtual circuit, usually on a leased line such as T1/E1, or at minimum ISDN or DSL.
In broadcasting, and to some extent in studio and even live production, many manufacturers equip their own audio engines to be tied together. This may also be done with gigabit Ethernet and optical fibre rather than wire. This allows each studio to have its own engine, or for auxiliary studios to share an engine. By connecting them together, different sources can be shared among them.
AoE is not necessarily intended for wireless networks, thus the use of various 802.11 devices may or may not work with various (or any) AoE protocols.
See also
Comparison of audio network protocols
Ethernet Powerlink
HDBaseT
References
Audio engineering
Broadcast engineering
Ethernet
Audio network protocols | Audio over Ethernet | [
"Engineering"
] | 1,479 | [
"Electronic engineering",
"Broadcast engineering",
"Audio engineering",
"Electrical engineering"
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5,431,652 | https://en.wikipedia.org/wiki/Mar%20Menor | Mar Menor (, "minor/smaller sea") is a coastal saltwater lagoon in the Iberian Peninsula located south-east of the Autonomous Community of Murcia, Spain, near Cartagena.
Its name is the opposite of the Mediterranean, which is the (greater/larger sea) of the region.
Four municipalities border the Mar Menor: Cartagena, Los Alcázares, San Javier and San Pedro del Pinatar.
With a surface area of 135 km2, a coastal length of 70 km, and warm and clear water no more than 7 metres in depth, it is the largest lagoon in Spain.
The lagoon is separated from the Mediterranean Sea by La Manga ("the sleeve"), a sandbar 22 km in length whose width ranges from 100 to 1,200 metres, with Cape Palos in its south-eastern vertex making for the lagoon's roughly triangular shape. There are five islets located within the lagoon: Perdiguera islet, Mayor or El Barón islet, Ciervo islet, Redonda islet and del Sujeto islet.
Its relatively high salinity (which aids flotation), low waves, and remarkable sporting infrastructures makes it a popular place for a wide variety of water sports.
Ecological importance
At the northern end there are salt flats, which include a wetland of international importance. This area is preserved as a natural park administered by the regional government: the (‘San Pedro del Pinatar salt flats and sand beaches’). The microbes that live in this coastal lagoon have been recently described.
The islets and the few coastal places without permanent human constructions are a protected landscape: the (‘Mar Menor open areas and islands’).
In 1994 the Mar Menor was included on the Ramsar Convention list for the conservation and sustainable utilisation of wetlands.
The Mar Menor is also part of a Specially Protected Area of Mediterranean Importance and is a Special Protection Area (ZEPA in Spanish) for bird life.
In July 2016 pollution was reportedly so severe as to render the area close to ecological collapse, following 18 years of neglected warnings. The public prosecutor's office is investigating allegations of negligence against the relevant authorities, which are governed by the conservative People's Party
In May 2017 all beaches of the Mar Menor were stripped of their Blue Flag status as a result of the polluted condition of the Mar Menor in 2016.
In October 2019 the pollution entering after floods in September led to thousands of dead fish lining the beaches, having suffocated due to a lack of oxygen. Intensive farming in surrounding areas leads to high levels of nitrates, ammonium and phosphates from fertilizers being washed into the lagoon, causing eutrophication, an excessive growth of algae and bacteria that deprives the water of oxygen.
A similar event occurred in August 2021, with four to five tons of dead fish being removed from the lagoon within a week. Shortly thereafter, a large demonstration took place, with 70,000 people surrounding the entire lagoon on August 28, 2021.
Legal status
Beginning in 2018 in response to the recurring hypoxic events, activists from civil society have lobbied under the name of "ILP (Iniciativa Legisativa Popular) Mar Menor" for a law that would recognize the right of the Mar Menor ecosystem to exist, treating it as a "legal person" following the legal paradigm of rights of nature. In October 2022, Spanish lawmakers granted these rights, making the Mar Menor the first case of an ecosystem protected by rights of nature in Europe. The Mar Menor is now legally represented by a group of citizens, scientists and officials; furthermore, anyone can bring legal action on behalf of Mar Menor, without first having to prove legal standing.
Panoramic view of Mar Menor and La Manga
Notes
External links
Mar Menor Tourism Site
Unofficial La Manga del Mar Menor Tourism guide
Mar Menor Activities
Abracemos al Mar Menor is an international group of volunteers dedicated to raising awareness about the ecocide of the Mar Menor and La Manga, aiming for its recovery before it becomes irreversible. Their work focuses on protecting this unique and exceptional environment, promoting actions to prevent its deterioration.
Environmental personhood
Landforms of the Region of Murcia
Lagoons of Europe
Coastal lagoons
Bodies of water of Spain
Wetlands of Spain
Ramsar sites in Spain
Special Protection Areas of Spain
World Heritage Sites in Spain
Biosphere reserves of Spain
Birdwatching sites in Spain
Eutrophication
Protected areas of the Region of Murcia | Mar Menor | [
"Chemistry",
"Environmental_science"
] | 937 | [
"Environmental ethics",
"Eutrophication",
"Environmental chemistry",
"Water pollution",
"Environmental personhood",
"Mar Menor"
] |
5,432,154 | https://en.wikipedia.org/wiki/Virgil%20Widrich | Virgil Widrich (* 16 May 1967 in Salzburg) is an Austrian director, screenwriter, filmmaker and multimedia artist.
Widrich works on a large number of films and multimedia projects, sometimes as part of a creative team. He is known especially for his numerous short films and multimedia works.
Biography
Born in Salzburg, Virgil Widrich spent his childhood in a house that is over 500 years old and stands on the Mönchsberg. While there he became acquainted with artists such as Peter Handke, who was his neighbour, and film director Wim Wenders, a frequent visitor. He gained his first experience with film at a very young age and was given his first camera, a Super-8, at the age of 13. That same year (1980) he made three films, "My Homelife", "Gebratenes Fleisch" and 3 mal Ulf. He followed that with an animated cartoon titled Auch Farbe kann träumen. At the age of 15 he made Monster in Salzburg, on which he worked with actors for the first time. He created the rampaging monster using stop-motion photography. In 1983 he began work on Vom Geist der Zeit (Spirit of Time). Even bad grades at school were not enough to prevent him finishing his first feature-length movie, which took him 14 months. During this time he also took on a job as an extra and props manager at the Salzburg Festival to finance his films. In 1984 he began to take an interest in computers and programmed a number of simple games.
After passing his school-leaving exams at the Akademisches Gymnasium in Salzburg he entered the Vienna Film Academy, only to leave again after a matter of weeks to work on the script for a science fiction film which, in the end, he never made. In 1987 he founded the film distributing company Classic Films with two partners with the aim of distributing mainly artistic films. Later on he became assistant to John Bailey, a camera man and director, and in 1990 he went to Hollywood to work with Bailey on the science fiction comedy The Search for Intelligent Life in the Universe. After selling Classic Films in 1991 Widrich again turned his attention to the computer and the possibilities it offered for creating art. His next major project, which saw him working as production manager, was a new festival for Austrian film, held for the first time in 1993 under the name Diagonale. In the second year he also compiled a film database. More databases relating to film followed, and he was also involved in the creation of an interactive CD-ROM.
In 1997 Widrich started concentrating more on making his own films again, producing the short film "tx-transform", which was a great success at the Ars Electronica festival. He also returned to his script for Heller als der Mond ("Brighter than the Moon"), which he filmed in 1999. The film premiered in 2000 in Rotterdam. Copy Shop was his next project, and one of his most successful to date. Following its premiere in 2001 the film won 35 awards, was nominated for the Oscar and was shown on television and at over 200 film festivals. His next short, Fast Film, was likewise very successful, won 36 international awards and was shown on over 300 film festivals. A large number of multimedia projects for companies followed (in 2001 he founded the company, checkpointmedia AG, and is its CEO) and he continued producing films with his company Virgil Widrich Film- und Multimediaproduktionen G.m.b.H. Together with other filmmakers he also co-founded the production company Amour Fou Film in 2001, focusing on arthouse movies from young directors.
In 2004 Widrich was a member of the jury for Ars Electronica and became chairman of the Austrian Film Directors’ Association until 2007. He is also a member of the Academy of Austrian Film. From 2007 to 2010 Virgil Widrich taught as Professor at the University of Applied Arts Vienna, teaching the class of “digital arts”. Since 2010 he is the leading Professor of the post-graduate Master Programme "Art & Science".
Virgil Widrich has three sons with the film director Anja Salomonowitz, one of whom, Oskar Salomonowitz (born 2008), known for his role in the film "This Movie is a Gift", died in an accident in 2020.
Exhibitions
2006: Virgil Widrich created computer-animated installations for the refurbished Mozarthaus Vienna.
2008: 13 works by Virgil Widrich and his students of “digital arts” were displayed at the “Essence08” in the Museum für angewandte Kunst Wien.
2009: Virgil Widrich took on the role as art director for the exhibition "Linz. City in Luck" at the museum Nordico, that formed part of the city's year as European Capital of Culture.
2009: "Alias in Wonderland" took place from 25 June to 12 July in the Freiraum/quartier 21 in the Museumsquartier in Vienna, a project carried out with his students.
2009: 10 works by his students of “digital arts” were displayed at the “Essence09” in the Expositur Vordere Zollamtsstraße Vienna.
2010: 15 works by his students of “digital arts” were displayed at the “Essence10” in the Vienna Künstlerhaus.
2010: Widrich was artistic director of the exhibition “90 Jahre Salzburger Festspiele” (90 years of the Salzburg Festival) at the Salzburg Museum.
2011: Artistic director for the exhibition “parameter{world} - parameters for every or no thing” of the master “Art and Science” at the University of Applied Arts Vienna.
2012: Works by his students of “Art & Science” were displayed at the “Essence12” in the Vienna Künstlerhaus.
2013: "Crucial Experiments": exhibition of University of Applied Arts Vienna on behalf of Vienna Art Week 2013, MuseumsQuartier Wien/Ovalhalle, direction: Bernd Kräftner, Virgil Widrich
2014: 2 works by his students of “Art & Science” were displayed at the “Essence14” in the Vienna Künstlerhaus.
2015: "Parallaxis" – media installation for the exhibition "A Rush of Color" at Leopold Museum.
2016: [dis]placement – Information through Sound - of "Art & Science", Citygate Shopping, 1210 Vienna
2017: "Circuit Training", 6 June to 17 June 2017, the white house, 1010 Vienna
2017: Exhibition and retrospective "analog_digital - Die Dichotomie des Kinos", 3.10.2017 to 28.1. 2018, METRO Kinokulturhaus, 1010 Vienna: Film selection retrospective, participation in exhibition with two works
2017: Exhibition contribution "Panzerschrank Potemkin" at the Vienna Design Week
2017: Co-creation of the exhibition "Aesthetics of change – 150 years of the University of Applied Arts Vienna" at the MAK, Vienna
2018: Co-creation of "Sound of Music World", Salzburg
2018: Exhibition contribution "Voyage around my room" at the Vienna Design Week
Stage works
2012: Concept (in collaboration with Martin Haselböck and Frank Hoffmann), stage, visuals and film projections for "New Angels", which premiered on November 19, 2012 at the Théâtre National du Luxembourg.
Filmography
1980: My Homelife (A) 6 mins. (Documentary about an old house)
1980: Gebratenes Fleisch (A) 11 mins. (Crime thriller about the murder of a woman in a restaurant)
1980: 3 mal Ulf (A) 12 mins. (Documentary about Arnulf Komposch)
1981: Auch Farbe kann träumen (A) 12 mins. (Animated cartoon in which a worm and a little man flee from the destruction of the environment)
1982: Monster in Salzburg (A) 12 mins. (Animated film in which a monster goes on the rampage in Salzburg)
1983-85: Vom Geist der Zeit (A) 112 mins. (An assortment of many different genres)
1998: tx-transform (A) 5 mins. (Experimental animated film using intriguing techniques, co-directed by Martin Reinhart)
2000: Heller als der Mond (Brighter than the Moon) (Europe) 88 mins. (Comedy about being a foreigner in Vienna)
2001: Copy Shop (A) 12 mins. (A man copies himself until he fills the entire world)
2001: LinksRechts (A, F) 4 mins. (Interviews on the subject of "Left and right in film and politics")
2003: Fast Film (A, LUX) 14 mins. (animated film with printed scraps of other films telling the story of a chase)
2010: make/real (A), 5 mins. (Found-footage film for the exhibition "Robot Dreams" which was being staged at the Museum Tinguely in Basel and the Kunsthaus Graz
2011: warning triangle (A), 6 mins. (Found-footage film for the exhibition “Fetisch Auto. Ich fahre, also bin ich.” which was being staged at the Museum Tinguely in Basel
2015: back track (A), 7 mins. (Found-footage film in 3D)
2016: Vienna table trip (A), 1 min. 22 sec. (found-footage animated film)
2016: Night of a 1000 Hours (feature film)
2018: Icon Island – a live battle of pictures and sounds (AUT), 70 min. (Film and Music live-performance)
2018: Nena & Dave Stewart: Be my Rebel (D), 3 min. 45 sek., music video
2018: Light Matter (A), 5 min, experimental film
2019: tx-reverse (A, D), 5 min, experimental film, co-directed by Martin Reinhart
Since 2011 project development for a feature-length animated film titles "Micromeo", screenplay in collaboration with Jean-Claude Carrière).
Accolades
In total, Virgil Widrich's work has been awarded more than 290 international awards.
for Heller als der Mond (Brighter than the Moon) (2000):
Scriptwriting prize of the City of Salzburg for the best script (1997)
Jean Carment Award for Lars Rudolph — Angers European First Film Festival (2000)
Laser Vidéo Titres Award — Angers European First Film Festival (2000)
for Copy Shop (2001):
Academy Award for Best Live Action Short nomination
Prix de la meilleure création sonore / Best Music and Sound Design — Festival du Court-Métrage de Clermont-Ferrand (26 January 2001 - 3 February 2001)
Best Experimental Short — Toronto — International Short Film Festival (6 June 2001–10 June 2001)
Kodak Award — Jury's choice for short film — Puchon 2001 - Int. Fantastic Film Festival (12 July 2001–20 July 2001)
Jury Prize — IMAGO 2001 - Covilha, Portugal (25 September 2001–30 September 2001)
Silberne Taube — Leipzig 2001 – 44th International Film Festival (16 October 2001–21 October 2001)
Best Short film — Lleida 2001 - inCurt (7 November 2001–11 November 2001)
Best Experimental — Shorts International Film Festival New York 2001 (12 November 2001–15 November 2001)
1st Comunidad de Madrid Award — Best Film — Madrid — Semana de Cine Experimental (16 November 2001–23 November 2001)
Best Short film — Barcelona L'alternativa 01 (16 November 2001–24 November 2001)
Jury Prize — Leuven Kort 2001 - International Short Film Festival (23 November 2001 - 2 December 2001)
Best Of Festival — Boston Underground Film Festival (20 February 2002–24 February 2002)
Prix des télévisions européennes — Brussels 02 - Festival of Fantasy, Thriller and Science Fiction (15 March 2002–30 March 2002)
Special Prize — Hiroshima 2002 - International Animation Festival (22 August 2002–26 August 2002)
Best Experimental Film — Thessaloniki 02 - Panorama of Ind. Film and Video Makers (14 October 2002–21 October 2002)
Jury's special prize — Tehran International Animation Festival (23 February 2003–27 February 2003)
for Fast Film (2003):
Official selection Festival de Cannes (2003) (nomination)
Best Animated Short (C.O.R.E. Digital Pictures Award) - Worldwide Short Film Festival, Toronto (2003)
Grand Prix for Animation (Grande Prémio Animação) - Festival Internacional de Curtas Metragens de Vila do Conde, Portugal (2003)
Best Experimental Short Film – 52nd Int. Film Festival, Melbourne (2003)
Audience Award — Bearded Child Film Festival, Grand Rapids, MN / Boulder, CO USA (2003)
Most Imaginative Film — Odense Film Festival, Odense (2003)
High Risk Award — Fantoche – 4th International Festival for Animated Film, Zürich (2003)
Best Experimental Film — Panorama of Independent Film & Video Makers, Thessaloniki (2003)
Most innovative short — Leipzig International Festival for Documentaries and Animated Film (2003)
Grand Prix — Uppsala Short Film Festival (2003)
Premio de la Comunidad de Madrid a la Mejor Película — Semana de Cine Experimental de Madrid (2003)
Onda Curta, 2nd prize and jury's special mention — Cinanima Portugal (2003)
Innova Award — Animadrid, Spanien (2003)
Film Critics Award — Animafest Zagreb (2004)
ASIFA Korea Prize for best Experimental SICAF (2004)
Cartoon d'or — best animated cartoon Forum Galicia (2004)
Part of the Animation Show of Shows
for Nena & Dave Stewart: Be my Rebel (2018)
Mindfield Film Festival – Los Angeles – USA – Best Music Video: Platinum Award
UNDO Divergent Film Awards – Arlington – USA – Best Music Video
Mindfield Film Festival – Albuquerque – USA – Best Music Video: Platinum Award
EIFA – European Independent Film Award – Paris – Best Music Video – Bronze Award
Snowdance Film Awards – Los Angeles – USA – Best Visual VX
Fort Worth Indie Film Showcase – USA – Best International Music Video
NYC Indie Film Awards – USA – Best Music Video
Hollywood Sun Awards – USA – Best Music Video
Cosmic Film Festival – Florida – USA – Best Music Video
Rosarito International Film Festival – Los Angeles – USA – Best Music Video
Eurasia International Monthly Film Festival – Moskau – Best Music Video
Royal Wolf Film Awards – Los Angeles – USA – Winner: Best FX, Best Director, Best Music Video: Gold Award
Top Indie Film Awards – Online Festival – Winner: Best director, Best FX
Enginuity Film Awards – Shepherdstown – USA – Winner: Best New Media Director
West Wing Film Competition – Los Angeles – USA – Music Video: 1st Place Winner
Lake View International Film Festival – Punjab – Indien – May 2018 Best Music Video of the Month
Jaipur International Film Festival – JIFF – Indien – Top 2nd Music Video/Song
LA Edge Film Awards – Los Angeles – USA – Best Music Video, Best Editing, Best Visual FX
Silicon Beach Film Festival – Los Angeles – USA – Best Music Video
Berlin Flash Film Festival – Monthly category winner April 2018 – Music Video
SFAAF – South Film and Arts Academy Festival – Chile – Winner: best fx in a short film
Mediterranean Film Festival (MedFF) – Siracusa, Italien – Music Video Competition: Best Music Video
for checkpointmedia:
September 2006: National Award for the “Mozarthouse Vienna” in the category "culture and entertainment" and an award in the category "Public information and services" for the “Visitor Center of the Austrian Parliament”.
External links
Official Homepage
checkpointmedia
Master of Art and Science
Official YouTube channel
References
1967 births
Living people
Film people from Salzburg
Artists from Salzburg
Austrian film directors
Austrian animators
Collage filmmakers
Multimedia artists | Virgil Widrich | [
"Technology"
] | 3,229 | [
"Multimedia",
"Multimedia artists"
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5,432,239 | https://en.wikipedia.org/wiki/SNADS | SNADS or Systems Network Architecture Distribution Services is an "asynchronous
distribution service that can store data for delayed delivery."
SNADS uses SNA data links to allow messages and objects to be sent from system to system using the APPC protocol. It is a very robust service: once an object has been accepted by SNADS it will get to its destination. If the communication link is unavailable (down), the transmission will be held on the sending system until the link is available, at which time it is sent. If the transmission is interrupted, it will be resumed or re-sent once the communication problem is resolved.
SNADS is available on several IBM platforms, including IBM i, the AS/400 or System/38. Microsoft Exchange Server 5.5 Enterprise Edition includes a gateway called SNA Distribution Services (SNADS) Connector for communication with SNADS networks.
References
External links
SNADS documentation on ibm.com
See also
Systems Network Architecture
Systems Network Architecture | SNADS | [
"Technology"
] | 205 | [
"Computing stubs",
"Computer network stubs"
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5,432,386 | https://en.wikipedia.org/wiki/French%20Academy%20of%20Technologies | The National Academy of Technologies of France (Académie des technologies) is a learned society, founded in 2000, with an emphasis on technology, and the newest of French academies. In 2007 it acquired the status of établissement public, which enforces its public role.
Its stated missions are as follows:
Help to better exploit technologies in service of mankind
Provide clarity on emerging technologies
Contribute to public discussion of the risks and benefits of technologies
Contribute to professional and technological education
Interest the young and their parents in technologies and new careers
Raise public interest and comprehension in technologies
In 2021 the academy had approximately 350 active members, including emeritus and foreign members. It is organized into a number of commissions, committees, and work groups on subjects including information technology, ethics, energy and the environment, transport, simulation, defense, etc.
See also
French Academy of Sciences
External links
National Academy of Technologies of France
France
National academies of engineering | French Academy of Technologies | [
"Engineering"
] | 182 | [
"National academies of engineering"
] |
5,434,119 | https://en.wikipedia.org/wiki/Misalignment%20mechanism | It is a well known fact that a quarter of the energy density of the universe is in the form of dark matter (DM). One can corroborate the presence of DM by alluding to the observational data such as anisotropies in Cosmic Microwave Background (CMB) radiation and the formation of Large scale structure in the universe. There are various schools of thought with differing positions on the nature of DM, but they mostly converge on the fact that the mass of DM lies within the range of eV to .
Such light-weight, spinless DM, with no or little self-interaction between themselves
is described by the classical scalar field. Axion is the example of field-like DM.
The interaction of axions with the other particles is assumed to be too weak for axions to reach thermal equilibrium with the rest of the early universe plasma, implying that they were produced non-thermally. The production mechanism of such particles is the vacuum misalignment mechanism which is a hypothesized effect in the Peccei–Quinn theory proposed solution to the strong-CP problem in quantum mechanics. The effect occurs when a particle's field has an initial value that is not at or near a potential minimum. This causes the particle's field to oscillate around the nearest minimum, eventually dissipating energy by decaying into other particles until the minimum is attained.
In the case of hypothesized axions created in the early universe, the initial values are random because of the masslessness of axions in the high temperature plasma. Near the critical temperature of quantum chromodynamics, axions possess a temperature-dependent mass that enters a damped oscillation until the potential minimum is reached.
There are other production mechanism for cold DM axions, but it is least model dependent provided that the Hubble parameter is much greater than the axion mass well before matter - radiation equality. The expansion of the universe acts as a friction term, freezing the axion amplitude at a constant value .
The action in the minimally coupled scalar field theory is given by
where is the determinant of FLRW metric . The dynamics of these particles are a Klein-Gordon equation in a homogeneous and isotropic space-time, of which scale factor a(t) evolves as determined by the Hubble parameter . Near the minimum of its potential, where , of which then behaves cosmologically as a damped harmonic oscillator:
Due to the expansion of the universe, dropped below , the damping becomes undercritical and the field can roll down and start oscillating near the bottom of the potential. In this case, the solution of field equation can be deduced by WKB approximation.
The energy density of these fields dilutes with the scale factor. It can be shown that the axion density provides a fraction a of the critical density given by,
The φ oscillations, which can be interpreted as a set of particles, therefore have the red shifting behavior of (non-relativistic) matter, making this a suitable dark matter candidate.
References
2. Asimina Arvanitaki etal; (1 January 2020). The Large-Misalignment Mechanism for the Formation of Compact Axion Structures:
Signatures from the QCD Axion to Fuzzy Dark Matter; arXiv:1909.11665v2 [astro-ph.CO] 30 Dec 2019
Physics beyond the Standard Model
Astroparticle physics | Misalignment mechanism | [
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5,434,343 | https://en.wikipedia.org/wiki/Music%20Express | A Music Express is an amusement ride based on the original Caterpillar rides of Germany. Several near-identical ride designs are also produced by other companies: Musik Express by Italian company Bertazzon and US Majestic Rides, Himalaya by American company Wisdom Rides,
German company Mack, and French company Reverchon, and Silver Streak by Wisdom Rides. This ride is a modern adaptation of the famous Harry Traver Caterpillar rides.
Design and operation
The ride features twenty 3-passenger cars connected in a circle. These cars rotate on a track with alternating sloped and flat sections. Rotation is possible in both a backward and forward direction, as the ride is manually operated. The ride is powered by 4 DC motors, and can reach a maximum speed of 12 revolutions per minute. (Certain older models have a hydraulic tire/rim drive and they have a tendency to go faster).
The riders in each car are restrained by a single solid lap bar that is locked across the body of the car, making the ride unsuitable for young children or people of short stature. The bar must be manually locked or unlocked, and only locks in one position. Lights and music are also controlled by the operator, which (as the name suggests) contribute heavily to the ride experience. After a certain amount of rotations or minutes, the ride operator will be alerted by the control box that the speed is going to increase, usually by a light on the box. At that time the operator will speak on a microphone asking the riders if they would like to go faster. Sometimes the ride operator can do this earlier than the alert light to build suspense. After a minute or two of faster speed, the ride will then slow down, and the operator can then ask the riders if they would like to go backwards. The speed up element is then repeated again only done in reverse. Most parks and carnivals require riders to be at least 42 inches or even taller, depending on circumstances and ride design.
Most Musik Expresses are built with a backdrop dividing the rear third of the ride from the front two-thirds. This backdrop, normally covered in artwork and lights, and providing a mild headchopper-like effect as the riders enter and exit the rear section. As this blocks lines of sight, additional staff are required to safely supervise this ride in operation.
More common in Europe than the US, some Music Express rides have a canopy that the operator can cover the ride while in operation, very much like the old caterpillar rides.
At Kennywood Park's and Dorney Park & Wildwater Kingdom's Musik Express, written above are the words "Mit Musik Geht Alles Besser", which translated from German reads, "With Music Everything Goes Better."
The variant used in fairs across Hawaii feature murals of several famous artists, such as The Beatles, Jimi Hendrix, Janis Joplin, Elvis Presley, the logo of The Rolling Stones, and even fictional bands and singers.
Variations
Bertazzon Musik Express No major variations from Mack Rides version.
Majestic Manufacturing Musik Express 14 cars, hydraulic locking system, increased top RPM.
Wisdom Rides Himalaya 22 cars.
Mack Rides Himalaya Music Express, Diskothek
Reverchon Himalaya Original Himalaya ride design.
Wisdom Rides Silver Streak 16 cars, smaller height difference, multiple lap bar positions.
SDC Amor Express Billed as "The Love Machine", circa late 70s, with hydraulic drive and canopy, very much like the original caterpillar rides. Not many found in US anymore but they still can be found in European fair circuits and parks.
Appearances
References
Amusement rides
Articles containing video clips | Music Express | [
"Physics",
"Technology"
] | 734 | [
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5,434,910 | https://en.wikipedia.org/wiki/Bonner%20sphere | A Bonner sphere is a device used to determine the energy spectrum of a neutron beam. The method was first described in 1960 by Rice University's Bramblett, Ewing and Tom W. Bonner and employs thermal neutron detectors embedded in moderating spheres of different sizes. Comparison of the neutrons detected by each sphere allows accurate determination of the neutron energy. This detector system utilizes a few channel unfolding techniques to determine the coarse, few group neutron spectrum. The original detector system was capable of measuring neutrons between thermal energies up to ~20 MeV. These detectors have been modified to provide additional resolution above 20 MeV to energies up to 1 GeV.
Bonner sphere spectroscopy
Because of the complexity with which neutrons interact with the environment, precise determination of the neutron energy is quite difficult. Bonner sphere spectroscopy (BSS) is one of the few methods that provide an accurate measure of the neutron spectrum.
Remball
A single Bonner sphere of an appropriate size can be used for dosimetry, as the sensitivity of the detector will approximate the radiation weighting factor across a range of neutron energies. Such Bonner spheres are sometimes known as a remball.
See also
Neutron detection
References
Particle detectors
Spectrometers
Neutron instrumentation
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5,435,207 | https://en.wikipedia.org/wiki/Coprinopsis%20cinerea | Coprinopsis cinerea is a species of mushroom in the family Psathyrellaceae. Commonly known as the gray shag, it is edible, but must be used promptly after collecting.
Coprinopsis cinerea is an important model organism for studying fungal sex and mating types, mushroom development, and the evolution of multicellularity of fungi. The genome sequence was published in 2010. It is considered to be particularly suited organism to study meiosis, due to its synchronous meiotic development and prolonged prophase.
Research
Antibiotics
Researchers in 2014 discovered a protein produced by Coprinopsis cinerea with antibiotic properties. The protein, known as copsin, has similar effects to other non-protein organically derived antibiotics. To date, it has not been determined whether antibiotic medicine for humans and other animals can be developed from this protein.
Culturing
Coprinopsis cinerea can be grown on complex (e.g. YMG, YMG/T) or minimal media (e.g. mKjalke medium), solid or liquid, with or without agitation, at 25 °C or optimally at 37 °C. It can be grown in dark or with 12-h light/12-h dark cycle.
Strains
C. cinereus strain PG78 (A6B42, trp1.1;1.6, pab1) is an AmutBmut monokaryon, self-compatible strain, with trp- and pab-auxotrophic markers (requires tryptophan and p-aminobenzoate).
Genome
Coprinopsis cinerea strain Okayama 7 (#130) was sequenced with 10x coverage in 2003. A third and most recent revision of the sequence of strain Okayama 7 (#130) was released in 2010. Its haploid genome is ca. 37.5 Mb.
Molecular cloning
Coprinopsis cinerea can be transformed with exogenous DNA by transformation when the fungus is a protoplast. It was found that disrupting (knockout or RNAi silencing) ku70 homologue can increase gene targeting via increased homologous recombination. Either protoplasts derived from oidia or vegetative mycelium can be used, however, gene targeting was found to be higher by 2% (based on phenotyping) when using vegetative mycelium. Otherwise, insertion of integrative vectors ectopically and with small homologous regions can be used, likely with low transformation efficiency.
Earlier, REMI (restriction enzyme-mediated integration) could be used to insert exogenous DNA into the chromosome to produce mutant strains. This relies on inserting exogenous DNA and restriction enzymes into the protoplast cell, allowing for the enzymes to cut the chromosome at specific sites which match those sites used to produce linearized plasmid DNA with the gene of interest; subsequently, host enzymes ligate the cut sites and thus produce integrated heterologous, exogenous DNA. Although successful, undesirable mutations are likely. Chemical mutagenesis (also random) can also be done. Phenotype selection of the inability to fruit can indicate that insertion led to disruption of vital genes. All in all, homologous recombination provides more specificity when creating a mutant strain. Depending on the mutant, auxotrophy markers (requires lost gene to be inserted) or prototrophy (when causing essential gene deletion) be used for selection.
Enzymes
Coprinopsis cinerea is known to produce laccase, a type of phenoloxidase. C. cinerea produces a variety of the same laccase, known as isoenzymes. Laccase activity can be measured by zymograms (in which a substrate for the enzyme is present in a separating gel). Under stressed conditions, temperature and medium, laccase secretion was increased. Although copper is required co-factor for laccase, merely adding copper did not induce laccase secretion. It was recently found that a TET (Ten-Eleven translocation dioxygenases) homologue, CcTET, was identified in C. cinerea, which may have important human (or mammalian) implications like cancer. DNA methylation is vital in humans and dysfunction is associated with cancer, thus, studying methylation reactions in non-mammalians may provide better insight into mammalian methylation reactions.
Reproduction
Coprinopsis cinerea can sense blue light. It was identified that gene Cc.wc-2 is involved in blue light photoreception. Etiolated stipes (elongation without cap maturation) is caused when grown without light.
Meiosis
Coprinopsis cinerea is an ideal model for studying meiosis because meiosis progresses synchronously in about 10 million cells within each mushroom cap. Meiosis is a specialized cell division process, occurring in diploid cells, in which a single round of DNA replication occurs, and is followed by two divisions to produce four haploid daughter nuclei. During meiosis homologous chromosomes pair with each other and undergo a DNA repair process in which DNA damage is removed and genetic information is recombined. Burns et al. studied the expression of genes involved in the 15-hour meiotic process encompassing time points prior to the haploid nuclear fusion that forms the diploid zygote to the final formation of the four haploid products. They compared expression of particular genes in C. cinerea to the expression of the comparable genes (orthologs) in two other species (Saccharomyces cerevisiae and Schizosaccharomyces pombe) from which C. cinerea had diverged in evolution 500 to 900 million years ago. They found that the expression of individual genes turned on or off at the same stage in C. cinerea as in the other two species. They also found that genes considered to be specifically involved in the meiotic process were more conserved in their expression pattern than non-meiotic genes. These findings indicate ancient conservation of the meiotic process.
Human disease
Coprinopsis cinerea is harmless to human and animal health under normal conditions. However, the organism can cause opportunistic infections (mycoses) in immunocompromised patients, such as those who have undergone haematopoietic stem cell transplantation or are otherwise undergoing immunosuppression treatment. Most reported cases have been respiratory infections, but cases involving the heart, skin, brain or gut have been reported, and the infections may rapidly become systemic. Whilst exceptionally rare, Coprinopsis cinerea infection is difficult to treat and often fatal in this vulnerable patient group. The infection is caused by the mould-like asexual (non mushroom-forming) anamorph of Coprinopsis cinerea which used to be known as Hormographiella aspergillata, and may be described under this name in the clinical literature.
See also
List of Coprinopsis species
Cospin
References
cinerea
Edible fungi
Fungi of Asia
Fungi of Europe
Fungi of North America
Fungi described in 1774
Ammonia fungi
Taxa named by Jacob Christian Schäffer
Fungus species | Coprinopsis cinerea | [
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5,435,566 | https://en.wikipedia.org/wiki/Action-angle%20coordinates | In classical mechanics, action-angle variables are a set of canonical coordinates that are useful in characterizing the nature of commuting flows in integrable systems when the conserved energy level set is compact, and the commuting flows are complete. Action-angle variables are also important in obtaining the frequencies of oscillatory or rotational motion without solving the equations of motion. They only exist, providing a key characterization of the dynamics, when the system is completely integrable, i.e., the number of independent Poisson commuting invariants is maximal and the conserved energy surface is compact. This is usually of practical calculational value when the Hamilton–Jacobi equation is completely separable, and the separation constants can be solved for, as functions on the phase space. Action-angle variables define a foliation by invariant Lagrangian tori because the flows induced by the Poisson commuting invariants remain within their joint level sets, while the compactness of the energy level set implies they are tori. The angle variables provide coordinates on the leaves in which the commuting flows are linear.
The connection between classical Hamiltonian systems and their quantization in the Schrödinger wave mechanics approach is made clear by viewing the Hamilton–Jacobi equation as the leading order term in the WKB asymptotic series for the Schrodinger equation. In the case of integrable systems, the Bohr–Sommerfeld quantization conditions were first used, before the advent of quantum mechanics, to compute the spectrum of the hydrogen atom. They require that the action-angle variables exist, and that they be integer multiples of the reduced Planck constant . Einstein's insight in the EBK quantization into the difficulty of quantizing non-integrable systems was based on this fact.
Action-angle coordinates are also useful in perturbation theory of Hamiltonian mechanics, especially in determining adiabatic invariants. One of the earliest results from chaos theory, for dynamical stability of integrable dynamical systems under small perturbations, is the KAM theorem, which states that the invariant tori are partially stable.
In the modern theory of integrable systems action-angle variables were used in the solution of the Toda lattice, the definition of Lax pairs, or more generally, isospectral evolution of a linear operator characterizing integrable dynamics, and interpreting the associated spectral data as action-angle variables in the Hamiltonian formulation.
Derivation
Action angles result from a type-2 canonical transformation where the generating function is Hamilton's characteristic function (not Hamilton's principal function ). Since the original Hamiltonian does not depend on time explicitly, the new Hamiltonian is merely the old Hamiltonian expressed in terms of the new canonical coordinates, which we denote as (the action angles, which are the generalized coordinates) and their new generalized momenta . We will not need to solve here for the generating function itself; instead, we will use it merely as a vehicle for relating the new and old canonical coordinates.
Rather than defining the action angles directly, we define instead their generalized momenta, which resemble the classical action for each original generalized coordinate
where the integration path is implicitly given by the constant energy function . Since the actual motion is not involved in this integration, these generalized momenta are constants of the motion, implying that the transformed Hamiltonian does not depend on the conjugate generalized coordinates
where the are given by the typical equation for a type-2 canonical transformation
Hence, the new Hamiltonian depends only on the new generalized momenta .
The dynamics of the action angles is given by Hamilton's equations
The right-hand side is a constant of the motion (since all the s are). Hence, the solution is given by
where is a constant of integration. In particular, if the original generalized coordinate undergoes an oscillation or rotation of period , the corresponding action angle changes by .
These are the frequencies of oscillation/rotation for the original generalized coordinates . To show this, we integrate the net change in the action angle over exactly one complete variation (i.e., oscillation or rotation) of its generalized coordinates
Setting the two expressions for equal, we obtain the desired equation
The action angles are an independent set of generalized coordinates. Thus, in the general case, each original generalized coordinate can be expressed as a Fourier series in all the action angles
where is the Fourier series coefficient. In most practical cases, however, an original generalized coordinate will be expressible as a Fourier series in only its own action angles
Summary of basic protocol
The general procedure has three steps:
Calculate the new generalized momenta
Express the original Hamiltonian entirely in terms of these variables.
Take the derivatives of the Hamiltonian with respect to these momenta to obtain the frequencies
Degeneracy
In some cases, the frequencies of two different generalized coordinates are identical, i.e., for . In such cases, the motion is called degenerate.
Degenerate motion signals that there are additional general conserved quantities; for example, the frequencies of the Kepler problem are degenerate, corresponding to the conservation of the Laplace–Runge–Lenz vector.
Degenerate motion also signals that the Hamilton–Jacobi equations are completely separable in more than one coordinate system; for example, the Kepler problem is completely separable in both spherical coordinates and parabolic coordinates.
See also
Bohr–Sommerfeld model
Integrable system
Einstein–Brillouin–Keller method
Superintegrable Hamiltonian system
Tautological one-form
References
(hardcover) and (softcover)
Coordinate systems
Classical mechanics
Dynamical systems
Hamiltonian mechanics | Action-angle coordinates | [
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] |
2,956,909 | https://en.wikipedia.org/wiki/Nicolaou%20Taxol%20total%20synthesis | The Nicolaou Taxol total synthesis, published by K. C. Nicolaou and his group in 1994 concerns the total synthesis of taxol. Taxol is an important drug in the treatment of cancer but also expensive because the compound is harvested from a scarce resource, namely the pacific yew.
This synthetic route to taxol is one of several; other groups have presented their own solutions, notably the group of Holton with a linear synthesis starting from borneol, the Samuel Danishefsky group starting from the Wieland-Miescher ketone and the Wender group from pinene.
The Nicolaou synthesis is an example of convergent synthesis because the molecule is assembled from three pre-assembled synthons. Two major parts are cyclohexene rings A and C that are connected by two short bridges creating an 8 membered ring in the middle (ring B). The third pre-assembled part is an amide tail. Ring
D is an oxetane ring fused to ring C. Two key chemical transformations are the Shapiro reaction and the pinacol coupling reaction.
The overall synthesis was published in 1995 in a series of four papers.
Retrosynthesis
As illustrated in Retrosynthetic Scheme I, Taxol was derived from diol 7.2 by an ester bond formation, according to the Ojima-Holton method. This diol comes from carbonate 6.3 by the addition of phenyllithium. The oxetane ring in compound 6.3 was obtained via an SN2 reaction involving a mesylate derived from acetal 4.9. Ring B was closed via a McMurry reaction involving dialdehyde 4.8 which ultimately was derived from aldehyde 4.2 and hydrazone 3.6 using a Shapiro coupling reaction.
Retrosynthetic Scheme II indicates that both the aldehyde and the hydrazone used in the Shapiro coupling reaction were synthesized using Diels-Alder reactions.
C Ring synthesis
As shown in Scheme 1, the ring synthesis of ring C began with a Diels-Alder reaction between diene 1.3 and dienophile 1.1 in the presence of phenylboronic acid (1.2), which, after addition of 2,2-dimethyl-1,3-propanediol, gave five-membered lactone 1.8 in 62% yield. Boron served as a molecular tether and aligned both diene and dienophile for this endo Diels-Alder cycloaddition. After protection of the hydroxyl groups as tert-butyldimethylsilyl ethers, reduction of the ester with lithium aluminium hydride and selective deprotection of the secondary hydroxyl group gave lactone diol 1.11. The unusual lactone hydrates 1.9 and 1.10 were isolated as synthetic intermediates in this process.
Lactone diol 2.1, after selective protection, was reduced with lithium aluminium hydride to give triol 2.4. This triol, after conversion to the acetonide, was selectively oxidized to the aldehyde using tetrapropylammonium perruthenate (TPAP) and N-methylmorpholine N-oxide. Aldehyde 2.6 served as a starting point for the construction of ring B (Scheme 4, compound 4.2).
A ring synthesis
The A ring synthesis (Scheme 3) started with a Diels-Alder reaction of diene 3.1 with the commercially available dienophile 2-chloroacrylonitrile 3.2 to give cyclohexene 3.3 with complete regioselectivity. Hydrolysis of the cyanochloro group and simultaneous cleavage of the acetate group led to hydroxyketone 3.4. The hydroxyl group was protected as a tert-butyldimethylsilyl ether (3.5). In preparation for a Shapiro reaction, this ketone was converted to hydrazone 3.6.
B ring synthesis
The coupling of ring A and ring C created the 8 membered B ring. One connection was made via a nucleophilic addition of a vinyllithium compound to an aldehyde and the other connection through a pinacol coupling reaction of two aldehydes (Scheme 4).
A Shapiro reaction of the vinyllithium compound derived from hydrazone 4.1 with aldehyde 4.2 makes the first connection that will become the B ring. The control of stereochemistry in 4.3 is thought to be derived from the relative hindrance of the Si face in the orientation shown on the right, due to the proximity of the axial methyl group. Epoxidation with vanadyl(acetylacetate) converted alkene 4.3 to epoxide 4.4, which, upon reduction with lithium aluminium hydride, gave diol 4.5. This diol was then protected as carbonate ester 4.6. The carbonate group also served to create rigidity in the ring structure for the imminent pinacol coupling reaction. The two silyl ether groups were removed, and diol 4.7 was then oxidized to give dialdehyde 4.8 using N-methylmorpholine N-oxide in the presence of a catalytic amount of tetrapropylammonium perruthenate. In the final step of the formation of Ring B, a pinacol coupling using conditions developed by McMurry (titanium(III) chloride and a zinc/copper alloy) gave diol 4.9.
Resolution
At this point in the synthesis of Taxol, the material was a racemic mixture. To obtain the desired enantiomer, allylic alcohol 4.9 was acylated with (1S)-(−)-camphanic chloride and dimethylaminopyridine, giving two diastereomers. These were then separated using standard column chromatography. The desired enantiomer was then isolated when one of the separated disatereomers was treated with potassium bicarbonate in methanol.
D ring synthesis
The desired enantiomer from resolution, allylic alcohol 5.1 (Scheme 5) was acetylated with acetic anhydride and 4-(dimethylamino)pyridine in methylene chloride to yield monoacetate 5.2. It is noteworthy that this reaction was exclusive for the allylic alcohol, and the adjacent hydroxyl group was not acetylated. Alcohol 5.2 was oxidized with tetrapropylammonium perruthenate and N-methylmorpholine N-oxide to give ketone 5.3. Alkene 5.3 underwent hydroboration in tetrahydrofuran. Oxidation with basic hydrogen peroxide and sodium bicarbonate gave alcohol 5.4 in 35% yield, with 15% yield of a regioisomer. The acetonide was removed, giving triol 5.5. This alcohol was monoacetylated, to give acetate 5.6. The benzyl group was removed and replaced with a triethylsilyl group. Diol 5.7 was selectively activated using methanesulfonyl chloride and 4-(dimethylamino)pyridine to give mesylate 5.8, in 78% yield.
The acetyl group in 6.1 (Scheme 6) was removed to give primary alcohol 6.2. The Taxol ring (D) was added by an intramolecular nucleophilic substitution involving this hydroxyl group to give oxetane 6.3. After acetylation, phenyllithium was used to open the carbonate ester ring to give alcohol 6.5. Allylic oxidation with pyridinium chlorochromate, sodium acetate, and celite gave ketone 6.6, which was subsequently reduced using sodium borohydride to give secondary alcohol 6.7. This was the last compound before the addition of the amide tail.
Tail addition
As shown in Scheme 7, Ojima lactam 7.1 reacted with alcohol 7.2 with sodium bis(trimethylsilyl)amide as a base. This alcohol is the triethylsilyl ether of the naturally occurring compound baccatin III. The related compound, 10-deacetylbaccatin III, is found in Taxus baccata, also known as the European Yew, in concentrations of 1 gram per kilogram leaves. Removal of the triethylsilyl protecting group gave Taxol.
Precursor synthesis
Synthesis of the Diels-Alder dienophile for Ring C
The ethyl ester of propionic acid (1) was brominated and then converted to the Wittig reagent using triphenylphosphine. Aldehyde 6 was obtained from allyl alcohol (4) by protection as the tert-butyldiphenylsilyl ether (5) followed by ozonolysis. Wittig reagent 3 and aldehyde 6 reacted in a Wittig reaction to give unsaturated ester 7, which was deprotected to give dienophile 8 (Scheme 1, compound 1).
Synthesis of the Diels-Alder diene for Ring A
Aldol condensation of acetone and ethyl acetoacetate gave β-keto-ester 3. A Grignard reaction involving methylmagnesium bromide provided alcohol 4, which was subjected to acid catalyzed elimination to give diene 5. Reduction and acetylation gave diene 7 (Scheme 3, compound 1).
Protecting groups
The synthesis makes use of various protecting groups as follows:
See also
Paclitaxel total synthesis
Danishefsky Taxol total synthesis
Holton Taxol total synthesis
Kuwajima Taxol total synthesis
Mukaiyama Taxol total synthesis
Wender Taxol total synthesis
External links
Nicolaou Taxol Synthesis @ SynArchive.com
Taxol in dynamic 3D
References
Total synthesis
Scripps Research
Taxanes | Nicolaou Taxol total synthesis | [
"Chemistry"
] | 2,110 | [
"Total synthesis",
"Chemical synthesis"
] |
2,957,180 | https://en.wikipedia.org/wiki/Cairo%20pentagonal%20tiling | In geometry, a Cairo pentagonal tiling is a tessellation of the Euclidean plane by congruent convex pentagons, formed by overlaying two tessellations of the plane by hexagons and named for its use as a paving design in Cairo. It is also called MacMahon's net after Percy Alexander MacMahon, who depicted it in his 1921 publication New Mathematical Pastimes. John Horton Conway called it a 4-fold pentille.
Infinitely many different pentagons can form this pattern, belonging to two of the 15 families of convex pentagons that can tile the plane. Their tilings have varying symmetries; all are face-symmetric. One particular form of the tiling, dual to the snub square tiling, has tiles with the minimum possible perimeter among all pentagonal tilings. Another, overlaying two flattened tilings by regular hexagons, is the form used in Cairo and has the property that every edge is collinear with infinitely many other edges.
In architecture, beyond Cairo, the Cairo tiling has been used in Mughal architecture in 18th-century India, in the early 20th-century Laeiszhalle in Germany, and in many modern buildings and installations. It has also been studied as a crystal structure and appears in the art of M. C. Escher.
Structure and classification
The union of all edges of a Cairo tiling is the same as the union of two tilings of the plane by hexagons. Each hexagon of one tiling surrounds two vertices of the other tiling, and is divided by the hexagons of the other tiling into four of the pentagons in the Cairo tiling. Infinitely many different pentagons can form Cairo tilings, all with the same pattern of adjacencies between tiles and with the same decomposition into hexagons, but with varying edge lengths, angles, and symmetries. The pentagons that form these tilings can be grouped into two different infinite families, drawn from the 15 families of convex pentagons that can tile the plane, and the five families of pentagon found by Karl Reinhardt in 1918 that can tile the plane isohedrally (all tiles symmetric to each other).
One of these two families consists of pentagons that have two non-adjacent right angles, with a pair of sides of equal length meeting at each of these right angles. Any pentagon meeting these requirements tiles the plane by copies that, at the chosen right angled corners, are rotated by a right angle with respect to each other. At the pentagon sides that are not adjacent to one of these two right angles, two tiles meet, rotated by a 180° angle with respect to each other. The result is an isohedral tiling, meaning that any pentagon in the tiling can be transformed into any other pentagon by a symmetry of the tiling. These pentagons and their tiling are often listed as "type 4" in the listing of types of pentagon that can tile. For any type 4 Cairo tiling, twelve of the same tiles can also cover the surface of a cube, with one tile folded across each cube edge and three right angles of tiles meeting at each cube vertex, to form the same combinatorial structure as a regular dodecahedron.
The other family of pentagons forming the Cairo tiling are pentagons that have two complementary angles at non-adjacent vertices, each having the same two side lengths incident to it. In their tilings, the vertices with complementary angles alternate around each degree-four vertex. The pentagons meeting these constraints
are not generally listed as one of the 15 families of pentagons that tile; rather, they are part of a larger family of pentagons (the "type 2" pentagons) that tile the plane isohedrally in a different way.
Bilaterally symmetric Cairo tilings are formed by pentagons that belong to both the type 2 and type 4 families. The basketweave brick paving pattern can be seen as a degenerate case of the bilaterally symmetric Cairo tilings, with each brick (a rectangle) interpreted as a pentagon with four right angles and one 180° angle.
It is possible to assign six-dimensional half-integer coordinates to the pentagons of the tiling, in such a way that the number of edge-to-edge steps between any two pentagons equals the distance between their coordinates. The six coordinates of each pentagon can be grouped into two triples of coordinates, in which each triple gives the coordinates of a hexagon in an analogous three-dimensional coordinate system for each of the two overlaid hexagon tilings. The number of tiles that are steps away from any given tile, for , is given by the coordination sequence
in which, after the first three terms, each term differs by 16 from the term three steps back in the sequence. One can also define analogous coordination sequences for the vertices of the tiling instead of for its tiles, but because there are two types of vertices (of degree three and degree four) there are two different coordination sequences arising in this way. The degree-four sequence is the same as for the square grid.
Special cases
Catalan tiling
The snub square tiling, made of two squares and three equilateral triangles around each vertex, has a bilaterally symmetric Cairo tiling as its dual tiling. The Cairo tiling can be formed from the snub square tiling by placing a vertex of the Cairo tiling at the center of each square or triangle of the snub square tiling, and connecting these vertices by edges when they come from adjacent tiles. Its pentagons can be circumscribed around a circle. They have four long edges and one short one with lengths in the ratio . The angles of these pentagons form the sequence 120°, 120°, 90°, 120°, 90°.
The snub square tiling is an Archimedean tiling, and as the dual to an Archimedean tiling this form of the Cairo pentagonal tiling is a Catalan tiling or Laves tiling. It is one of two monohedral pentagonal tilings that, when the tiles have unit area, minimizes the perimeter of the tiles. The other is also a tiling by circumscribed pentagons with two right angles and three 120° angles, but with the two right angles adjacent; there are also infinitely many tilings formed by combining both kinds of pentagon.
Tilings with collinear edges
Pentagons with integer vertex coordinates , , and , with four equal sides shorter than the remaining side, form a Cairo tiling whose two hexagonal tilings can be formed by flattening two perpendicular tilings by regular hexagons in perpendicular directions, by a ratio of . This form of the Cairo tiling inherits the property of the tilings by regular hexagons (unchanged by the flattening), that every edge is collinear with infinitely many other edges.
Tilings with equal side lengths
The regular pentagon cannot form Cairo tilings, as it does not tile the plane without gaps. There is a unique equilateral pentagon that can form a type 4 Cairo tiling; it has five equal sides but its angles are unequal, and its tiling is bilaterally symmetric. Infinitely many other equilateral pentagons can form type 2 Cairo tilings.
Applications
Several streets in Cairo have been paved with the collinear form of the Cairo tiling; this application is the origin of the name of the tiling. As of 2019 this pattern can still be seen as a surface decoration for square tiles near the Qasr El Nil Bridge and the El Behoos Metro station; other versions of the tiling are visible elsewhere in the city. Some authors including Martin Gardner have written that this pattern is used more widely in Islamic architecture, and although this claim appears to have been based on a misunderstanding, patterns resembling the Cairo tiling are visible on the 17th-century Tomb of I'timād-ud-Daulah in India, and the Cairo tiling itself has been found on a 17th-century Mughal jali.
One of the earliest publications on the Cairo tiling as a decorative pattern occurs in a book on textile design from 1906. Inventor H. C. Moore filed a US patent on tiles forming this pattern in 1908. At roughly the same time, Villeroy & Boch created a line of ceramic floor tiles in the Cairo tiling pattern, used in the foyer of the Laeiszhalle in Hamburg, Germany. The Cairo tiling has been used as a decorative pattern in many recent architectural designs; for instance, the city center of Hørsholm, Denmark, is paved with this pattern, and the Centar Zamet, a sports hall in Croatia, uses it both for its exterior walls and its paving tiles.
In crystallography, this tiling has been studied at least since 1911. It has been proposed as the structure for layered hydrate crystals, certain compounds of bismuth and iron, and penta-graphene, a hypothetical compound of pure carbon. In the penta-graphene structure, the edges of the tiling incident to degree-four vertices form single bonds, while the remaining edges form double bonds. In its hydrogenated form, penta-graphane, all bonds are single bonds and the carbon atoms at the degree-three vertices of the structure have a fourth bond connecting them to hydrogen atoms.
The Cairo tiling has been described as one of M. C. Escher's "favorite geometric patterns". He used it as the basis for his drawing Shells and Starfish (1941), in the bees-on-flowers segment of his Metamorphosis III (1967–1968), and in several other drawings from 1967–1968. An image of this tessellation has also been used as the cover art for the 1974 first edition of H. S. M. Coxeter's book Regular Complex Polytopes.
References
External links
Isohedral tilings
Pentagonal tilings
Semiregular tilings
Culture in Cairo | Cairo pentagonal tiling | [
"Physics"
] | 2,072 | [
"Tessellation",
"Isohedral tilings",
"Semiregular tilings",
"Symmetry"
] |
2,957,347 | https://en.wikipedia.org/wiki/Screen%20hotspot | A screen hotspot, in computing, provides a special area on the display screen of a computer for hyperlinking or for other GUI-based activity (such as re-direction, pop-up display, macro execution, etc.).
Hotspots may not look visually distinct; however, a mouseover operation over elements such as hyperlinks, buttons or idle windows will often reveal them by changing the shape of the pointer.
The corners and edges of the whole screen may also act as hotspots. Some screen savers under DOS and older versions of Windows can be configured to be activated immediately (that is, without waiting for some period of inactivity to time out) or to never activate the screen saver mode at all (even after timeout) when the mouse is moved into a particular (often configurable) corner of the screen.
Hotspots are used extensively in Windows 8, where they are referred to as "hot corners".
According to Fitts's law, which predicts the time it takes to reach a target area, moving mouse and trackball pointers to those spots is easy and fast. As the pointer usually stops when reaching a screen edge, the size of those spots can be considered of virtual infinite size, so the hot corners and edges can be reached quickly by throwing the pointer toward the edges.
See also
Context menu
Image map
References
Hypertext | Screen hotspot | [
"Technology"
] | 287 | [
"Computing stubs"
] |
2,957,537 | https://en.wikipedia.org/wiki/Dream%20telepathy | Dream telepathy is the purported ability to communicate telepathically with another person while one is dreaming. Mainstream scientific consensus rejects dream telepathy as a real phenomenon. Parapsychological experiments into dream telepathy have not produced replicable results. The first person in modern times to claim to document telepathic dreaming was Sigmund Freud. In the 1940s, it was the subject of the Eisenbud-Pederson-Krag-Fodor-Ellis controversy, named after the preeminent psychoanalysts of the time who were involved: Jule Eisenbud, Geraldine Pederson-Krag, Nandor Fodor, and Albert Ellis.
History
The notion and speculation of communication via dreaming was first mooted in psychoanalysis by Sigmund Freud in 1921. He produced a model to express his ideas about telepathic dreaming. His 1922 paper Dreams and Telepathy is reproduced in the book Psychoanalysis and the Occult (1953) and was intended to be a lecture to the Vienna Psycho-Analytical Society, although he never delivered it. Freud considered that a connection between telepathy and dreams could be neither proven nor disproven. He was distinctly suspicious of the whole idea, noting that he himself had never had a telepathic dream. (His two dreams that were potentially telepathic, where he dreamed of the deaths of a son and of a sister-in-law, which did not occur, he labeled as "purely subjective anticipations".) His ideas were not widely accepted at the time, but he continued to publicly express his interest and findings about telepathic dreaming. He also observed that he had not encountered any evidence of dream telepathy in his patients. Freud claims neutrality about the phenomenon itself, states that the sleep milieu has special likely properties for it if it does exist, and discounts all of the cases presented to him on standard psychoanalytic grounds (e.g. neurosis, transference, etc.).
In the 1940s, Jule Eisenbud, Geraldine Pederson-Krag and Nandor Fodor described alleged cases of dream telepathy. Albert Ellis regarded their conclusions to have been based upon flimsy evidence, and thought that they could be better explained by bias, coincidence and unconscious cues than by dream telepathy. He also accused them of an emotional involvement in the notion, resulting in their observations and judgement being clouded. Psychologist L. Börje Löfgren also criticised dream telepathy experiments of Eisenbud. He stated that coincidence was a more likely explanation and the "assumption of paranormal forces to explain them is unnecessary."
Experiments
There have been many experiments done to test the validity of dream telepathy and its effectiveness, but with significant issues of blinding. Many test subjects find ways to communicate with others to make it look like telepathic communication. Attempts to cut off communication between the agent, sender, and receiver of information failed because subjects found ways to get around blindfolds no matter how intricate and covering they were. In studies at the Maimonides Medical Center in Brooklyn, New York led by Stanley Krippner and Montague Ullman, patients were monitored and awakened after a period of REM then separated to study the claimed ability to communicate telepathically. They concluded the results from some of their experiments supported dream telepathy.
The picture target experiments that were conducted by Krippner and Ullman were criticized by C. E. M. Hansel. According to Hansel there were weaknesses in the design of the experiments in the way in which the agent became aware of their target picture. Only the agent should have known the target and no other person until the judging of targets had been completed; however, an experimenter was with the agent when the target envelope was opened. Hansel also wrote there had been poor controls in the experiment as the main experimenter could communicate with the subject.
An attempt to replicate the experiments that used picture targets was carried out by Edward Belvedere and David Foulkes. The finding was that neither the subject nor the judges matched the targets with dreams above chance level. Results from other experiments by Belvedere and Foulkes were also negative.
In 2003, Simon Sherwood and Chris Roe wrote a review that claimed support for dream telepathy at Maimonides. However, James Alcock noted that their review was based on "extreme messiness" of data. Alcock concluded the dream telepathy experiments at Maimonides have failed to provide evidence for telepathy and "lack of replication is rampant."
The psychologist and noted skeptic Richard Wiseman took part in a dream telepathy experiment. It was conducted by Caroline Watt at a sleep laboratory in an attempt to replicate the results of Krippner and Ullman. The experiment was a complete failure. According to Wiseman, "after monitoring about twenty volunteers for several nights on end, the study didn't discover any evidence in support of the supernatural."
See also
Collective unconscious
Parapsychology
References
Further reading
Alcock, James (1981). Parapsychology: Science or Magic? A Psychological Perspective. Pergamon Press.
Telepathy
Paranormal terminology
Parapsychology
Psychic powers
Telepathy | Dream telepathy | [
"Biology"
] | 1,082 | [
"Dream",
"Behavior",
"Sleep"
] |
2,957,626 | https://en.wikipedia.org/wiki/Pimaric%20acid | Pimaric acid is a carboxylic acid that is classified as a resin acid. It is a major component of the rosin obtained from pine trees.
When heated above 100 °C, pimaric acid converts to abietic acid, which it usually accompanies in mixtures like rosin.
It is soluble in alcohols, acetone, and ethers. The compound is colorless, but almost invariably samples are yellow or brown owing to air oxidation. As a mixture with abietic acid, it is often hydrogenated, esterified, or otherwise modified to produce materials of commerce.
See also
Isopimaric acid
References
Carboxylic acids
Diterpenes
Phenanthrenes
Vinyl compounds | Pimaric acid | [
"Chemistry"
] | 149 | [
"Carboxylic acids",
"Functional groups",
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
2,957,726 | https://en.wikipedia.org/wiki/Battle%20of%20Changde | The Battle of Changde (Battle of Changteh; ) was a major engagement in the Second Sino-Japanese War in and around the Chinese city of Changde (Changteh) in the province of Hunan.
The purpose of the Japanese offensive was to maintain pressure on the Chinese National Revolutionary Army to reduce its combat ability in the region and its ability to reinforce the Burma Campaign.
The Japanese were initially successful in their offensive operation by bacteria-infected bombs and captured parts of the city of Changde, which forced civilians to evacuate. The Japanese were pinned down in the city by a Chinese division long enough for other Chinese units to surround them with a counterencirclement. Heavy casualties and the loss of their supply lines then forced the Japanese to withdraw, which returned territorial control to the original status quo.
Some contemporary Western newspapers depicted the battle as a Chinese victory. American government film footage showed victorious Chinese troops with Japanese prisoners and captured Japanese flags and equipment on display after the battle. In addition, an American newsreel titled Chinese troops drive Japs from Changteh showed Chinese troops firing, with dead and captured Japanese on display. A British newsreel titled Japs Loose Changteh Aka Japs Lose Changte showed similar footage.
Japanese offensive
On 2 November 1943 Isamu Yokoyama, commander of the Imperial Japanese 11th Army, deployed the 39th, 58th, 13th, 3rd, 116th and 68th divisions—a total of around 60,000 troops—to attack Changde from the north and the east. The Changde region was defended by the Chinese 6th War Zone's 10th, 26th, 29th and 33rd Army Groups, as well as a river defense force and two other corps, for a total of 14 corps.
On 14 November the Japanese 13th Division, with aid from collaborators, drove south and broke through the defensive lines of the Chinese 10th and the 29th Group Armies. On 16 November, Japanese airborne forces landed in Taoyuan County to support the assault on the city proper. At the same time, the Japanese 3rd and 116th Divisions also joined the combined assault. The city was guarded by one Chinese division - the 74th Corps' 57th. Division commander Yu Chengwan led 8,000 men to fight against the two invading Japanese divisions. Despite being outnumbered by more than three to one, the Chinese stubbornly held onto the city. Eleven days and nights of fierce fighting saw heavy casualties on both sides. When the Chinese reinforcements finally arrived in the city, they managed to evacuate the remaining 100 survivors in the 57th Division, all of whom were wounded, from the city. On 6 December the city of Changde fell to the Japanese control.
While the Chinese 57th Division pinned down the Japanese in the city, the rest of the 74th Corps, as well as the 18th, 73rd, 79th and 100th Corps and the 9th War Zone's 10th Corps, 99th Corps and Jiangxi's 58th Corps, arrived at the battlefield, forming a counter-encirclement on the Japanese forces.
Chinese counteroffensive
Fang Xianjue's 10th Corps was first to strike, successfully retaking Deshan on 29 November before attacking the Japanese positions at Changde from the south. Unable to withstand the fierce Chinese assault, the Japanese utilized chemical weapons. The battle lasted for six days and nights, during which the Chinese Reserve 10th Division's commander Lieutenant General Sun Mingjin received 5 gunshot wounds to the body and was killed in action.
At this time other Chinese units were also pressing onto the Japanese positions. On 11 December Chinese reinforcements broke through the Japanese lines and into the city, which resulted in intense house-to-house fighting. The Chinese then proceeded to cut the Japanese supply lines. Depleted of food and ammunition, the Japanese retreated on 13 December. The Chinese pursued them for more than 20 days. By 5 January 1944 Japanese forces had withdrawn to their original positions before the offensive. Following the battle, the Chinese displayed an array of captured Japanese weapons and equipment, as well as numerous Japanese troops taken as prisoners, for inspection by allied military observers.
During this campaign, apart from the Reserve 10th Division's Sun Mingjin, two other Chinese division commanders were killed: the 44th Corps' 150th Division's Lieutenant General Xu Guozhang was killed at Taifushan in Changde's northwest, aged 37, while the 73rd corps' 5th Division's Lieutenant General Peng Shiliang(:zh:彭士量) was killed at the Taoyuan-Shimen line, aged 38.
The Changde campaign saw the largest participation of the Chinese air force since the Battle of Wuhan.
Reporter Israel Epstein witnessed and reported on the battle. Witold Urbanowicz, a Polish fighter ace engaged in air combat over China in 1943, saw the city just after the battle.
In pop culture
The 2010 Chinese war film Death and Glory in Changde is based on the events in this battle.
See also
Order of Battle: Battle of Changde
References
Sources
External links
Axis History Forum Index; WW2 in the Pacific & Asia; Battle of Changde Order of Battle and Map, Photos from Changde () War Memorial
RESISTANCE WARS; Campaign of E-Xi, Battle Of Changde
Captured Japanese soldier
Conflicts in 1943
1943 in China
Changde 1943
Military operations involving chemical weapons
Military history of Hunan
November 1943 events in Asia
December 1943 | Battle of Changde | [
"Chemistry"
] | 1,086 | [
"Military operations involving chemical weapons"
] |
2,957,747 | https://en.wikipedia.org/wiki/Trimetaphan%20camsilate | Trimetaphan camsilate (INN) or trimethaphan camsylate (USAN), trade name Arfonad, is a sympatholytic drug used in rare circumstances to lower blood pressure.
Trimetaphan is a ganglionic blocker: it counteracts cholinergic transmission at a specific type of nicotinic acetylcholine receptors in the autonomic ganglia and therefore blocks both the sympathetic nervous system and the parasympathetic nervous system. It acts as a non-depolarizing competitive antagonist at the nicotinic receptor, is short-acting, and is given intravenously.
It was discovered by Leo Sternbach.
Effects
Trimetaphan is a sulfonium compound and therefore carries a positive charge. Being charged, it cannot cross lipid cell membranes, such as those that comprise the blood–brain barrier. Due to this, trimethaphan does not have any effect on the central nervous system.
The ciliary muscle of the eye functions to round the lens for accommodation and is controlled mainly by parasympathetic system input. With administration of a ganglion-blocking drug, the ciliary muscle cannot contract (cycloplegia) and the patient loses the ability to focus their eyes.
Trimetaphan has a strong effect on the cardiovascular system. The size of blood vessels is primarily controlled by the sympathetic nervous system. Loss of sympathetic system input to the blood vessels causes them to get larger (vasodilation) which has the effect of lowering blood pressure. Postural hypotension is a common side effect of such drugs. Trimethaphan causes a histamine release which further lowers blood pressure. Effects on the heart include a decreased force of contraction and an increase in heart rate (tachycardia). Reflexive tachycardia can be diminished or undetected because trimetaphan is also blocking the sympathetic ganglia innervating the heart.
The motility of the gastrointestinal tract is regulated by the parasympathetic system, and blockage of this input results in diminished motility and constipation.
A rare side effect of trimethaphan administration is sudden respiratory arrest. The mechanism behind it is unknown, as trimethaphan does not appear to block neuromuscular transmission, and respiratory arrest is not an expected consequence of ganglionic blockage.
Therapeutic uses
The therapeutic uses of trimetaphan are very limited due to the competition from newer drugs that are more selective in their actions and effects produced. It is occasionally used to treat a hypertensive crisis and dissecting aortic aneurysm, to treat pulmonary edema, and to reduce bleeding during neurosurgery.
References
Further reading
Imidazolidinones
Nicotinic antagonists
Peripherally selective drugs
Sulfonium compounds
Ureas
Drugs developed by Hoffmann-La Roche | Trimetaphan camsilate | [
"Chemistry"
] | 602 | [
"Organic compounds",
"Ureas"
] |
2,957,839 | https://en.wikipedia.org/wiki/Resin%20soap | Resin soap is a mix of salts (usually sodium) of resin acids (usually mainly abietic acid). It is a yellow gelatinous pasty soap with use in bleaching and cleaning and as a compound of some varnishes. It also finds use in rubber industry as an emulsifier. Often the soap is pretreated with formaldehyde and maleic anhydride.
Resin soap is made by reacting resin acids in wood with sodium hydroxide, as a byproduct of the Kraft process for manufacturing wood pulp. It is also called Kraft soap.
Acidification of the resin soap produces tall oil.
Pine soap is refined from resin soap via tall oil by acidification, refining and resaponification.
References
Resins
Soaps | Resin soap | [
"Physics"
] | 158 | [
"Amorphous solids",
"Unsolved problems in physics",
"Resins"
] |
2,957,941 | https://en.wikipedia.org/wiki/Marman%20clamp | A Marman clamp is a type of heavy-duty band clamp; it allows two cylindrical objects to be clamped together end-to-end with a ring clamp. It is sometimes also known as a "Marman ring". It consists of a circular strap with an interior V-shaped groove. Tension is applied to the strap with a threaded bolt and nuts connecting to the ends of the strap. As the tension increases, the V-groove wedges over flanges on the circular parts to be assembled, providing the force that holds the ends of the two cylinders together. The Marman clamp is an alternative to a bolted flange connection which would be heavier and require more labor to connect. Another variety uses a flat strap, used where systems carry low pressure or to hold a cylindrical object in position.
Hose connectors
A common use for Marman clamps is as quick-disconnect connectors in flexible aircraft fuel lines.
Spacecraft separation
Marman clamps are used extensively in spaceflight systems and are common mechanical load-transfer and clamping mechanisms for connecting the upper stage and the satellite payload of space vehicles, for example, on the Cassini Plasma Spectrometer on the Cassini orbiter. They may also be used to join stages of a booster rocket.
Early separation systems using Marman clamps used explosive bolts for release. These have problems of unpredictability, the need to contain debris and difficulties in testing them. A more recent approach uses a screw thread. The tension of the clamp band itself is used to power the unscrewing of a central bolt, when released by a pyrotechnic pin puller triggered by a set of redundant NASA Standard Initiators (NSIs).
History
The Marman clamp was first produced by Herbert Marx, better known by his stage name Zeppo Marx; it was manufactured by his company, Marman Products from the 1930s.
At the time it was designed to secure cargo during transport. The U.S. Military used Marman clamps to transport the atomic bombs used at the end of the Second World War.
Marman clamps are found in many modern moving vehicles, though the screw band type clamp is becoming more popular.
See also
Hose clamp
Jubilee Clip
References
External links
The CAPS Launch Latch
Clamps (tool)
Plumbing
Spaceflight technology | Marman clamp | [
"Engineering"
] | 479 | [
"Construction",
"Plumbing"
] |
2,957,962 | https://en.wikipedia.org/wiki/Quenching%20%28fluorescence%29 | In chemistry, quenching refers to any process which decreases the fluorescent intensity of a given substance. A variety of processes can result in quenching, such as excited state reactions, energy transfer, complex-formation and collisions. As a consequence, quenching is often heavily dependent on pressure and temperature. Molecular oxygen, iodine ions and acrylamide are common chemical quenchers. The chloride ion is a well known quencher for quinine fluorescence. Quenching poses a problem for non-instant spectroscopic methods, such as laser-induced fluorescence.
Quenching is made use of in optode sensors; for instance the quenching effect of oxygen on certain ruthenium complexes allows the measurement of oxygen saturation in solution. Quenching is the basis for Förster resonance energy transfer (FRET) assays. Quenching and dequenching upon interaction with a specific molecular biological target is the basis for activatable optical contrast agents for molecular imaging. Many dyes undergo self-quenching, which can decrease the brightness of protein-dye conjugates for fluorescence microscopy, or can be harnessed in sensors of proteolysis.
Mechanisms
Förster resonance energy transfer
There are a few distinct mechanisms by which energy can be transferred non-radiatively (without absorption or emission of photons) between two dyes, a donor and an acceptor. Förster resonance energy transfer (FRET or FET) is a dynamic quenching mechanism because energy transfer occurs while the donor is in the excited state. FRET is based on classical dipole-dipole interactions between the transition dipoles of the donor and acceptor and is extremely dependent on the donor-acceptor distance, R, falling off at a rate of 1/R6. FRET also depends on the donor-acceptor spectral overlap (see figure) and the relative orientation of the donor and acceptor transition dipole moments. FRET can typically occur over distances up to 100 Å.
Dexter electron transfer
Dexter (also known as Dexter exchange or collisional energy transfer, colloquially known as Dexter Energy Transfer) is another dynamic quenching mechanism. Dexter electron transfer is a short-range phenomenon that falls off exponentially with distance (proportional to e−kR where k is a constant that depends on the inverse of the van der Waals radius of the atom) and depends on spatial overlap of donor and quencher molecular orbitals. In most donor-fluorophore–quencher-acceptor situations, the Förster mechanism is more important than the Dexter mechanism. With both Förster and Dexter energy transfer, the shapes of the absorption and fluorescence spectra of the dyes are unchanged.
Dexter electron transfer can be significant between the dye and the solvent especially when hydrogen bonds are formed between them.
Exciplex
Exciplex (excited state complex) formation is a third dynamic quenching mechanism.
Static quenching
The remaining energy transfer mechanism is static quenching (also referred to as contact quenching). Static quenching can be a dominant mechanism for some reporter-quencher probes. Unlike dynamic quenching, static quenching occurs when the molecules form a complex in the ground state, i.e. before excitation occurs. The complex has its own unique properties, such as being nonfluorescent and having a unique absorption spectrum. Dye aggregation is often due to hydrophobic effects—the dye molecules stack together to minimize contact with water. Planar aromatic dyes that are matched for association through hydrophobic forces can enhance static quenching. High temperatures and addition of surfactants tend to disrupt ground state complex formation.
Collisional quenching
Collisional quenching occurs when the excited fluorophore experiences contact with an atom or molecule that can facilitate non-radiative transitions to the ground state. ... Excited-state molecule collides with quencher molecule and returns to ground state non-radiatively.
See also
Dark quencher, for use in molecular biology.
Förster resonance energy transfer, a phenomenon on which some quenching techniques rely
References
Fluorescence
Reaction mechanisms | Quenching (fluorescence) | [
"Chemistry"
] | 850 | [
"Reaction mechanisms",
"Luminescence",
"Fluorescence",
"Physical organic chemistry",
"Chemical kinetics"
] |
2,958,015 | https://en.wikipedia.org/wiki/Philosophy%20of%20artificial%20intelligence | The philosophy of artificial intelligence is a branch of the philosophy of mind and the philosophy of computer science that explores artificial intelligence and its implications for knowledge and understanding of intelligence, ethics, consciousness, epistemology, and free will. Furthermore, the technology is concerned with the creation of artificial animals or artificial people (or, at least, artificial creatures; see artificial life) so the discipline is of considerable interest to philosophers. These factors contributed to the emergence of the philosophy of artificial intelligence.
The philosophy of artificial intelligence attempts to answer such questions as follows:
Can a machine act intelligently? Can it solve any problem that a person would solve by thinking?
Are human intelligence and machine intelligence the same? Is the human brain essentially a computer?
Can a machine have a mind, mental states, and consciousness in the same sense that a human being can? Can it feel how things are? (i.e. does it have qualia?)
Questions like these reflect the divergent interests of AI researchers, cognitive scientists and philosophers respectively. The scientific answers to these questions depend on the definition of "intelligence" and "consciousness" and exactly which "machines" are under discussion.
Important propositions in the philosophy of AI include some of the following:
Turing's "polite convention": If a machine behaves as intelligently as a human being, then it is as intelligent as a human being.
The Dartmouth proposal: "Every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it."
Allen Newell and Herbert A. Simon's physical symbol system hypothesis: "A physical symbol system has the necessary and sufficient means of general intelligent action."
John Searle's strong AI hypothesis: "The appropriately programmed computer with the right inputs and outputs would thereby have a mind in exactly the same sense human beings have minds."
Hobbes' mechanism: "For 'reason' ... is nothing but 'reckoning,' that is adding and subtracting, of the consequences of general names agreed upon for the 'marking' and 'signifying' of our thoughts..."
Can a machine display general intelligence?
Is it possible to create a machine that can solve all the problems humans solve using their intelligence? This question defines the scope of what machines could do in the future and guides the direction of AI research. It only concerns the behavior of machines and ignores the issues of interest to psychologists, cognitive scientists and philosophers, evoking the question: does it matter whether a machine is really thinking, as a person thinks, rather than just producing outcomes that appear to result from thinking?
The basic position of most AI researchers is summed up in this statement, which appeared in the proposal for the Dartmouth workshop of 1956:
"Every aspect of learning or any other feature of intelligence can in principle be so precisely described that a machine can be made to simulate it."
Arguments against the basic premise must show that building a working AI system is impossible because there is some practical limit to the abilities of computers or that there is some special quality of the human mind that is necessary for intelligent behavior and yet cannot be duplicated by a machine (or by the methods of current AI research). Arguments in favor of the basic premise must show that such a system is possible.
It is also possible to sidestep the connection between the two parts of the above proposal. For instance, machine learning, beginning with Turing's infamous child machine proposal, essentially achieves the desired feature of intelligence without a precise design-time description as to how it would exactly work. The account on robot tacit knowledge eliminates the need for a precise description altogether.
The first step to answering the question is to clearly define "intelligence".
Intelligence
Turing test
Alan Turing reduced the problem of defining intelligence to a simple question about conversation. He suggests that: if a machine can answer any question posed to it, using the same words that an ordinary person would, then we may call that machine intelligent. A modern version of his experimental design would use an online chat room, where one of the participants is a real person and one of the participants is a computer program. The program passes the test if no one can tell which of the two participants is human. Turing notes that no one (except philosophers) ever asks the question "can people think?" He writes "instead of arguing continually over this point, it is usual to have a polite convention that everyone thinks". Turing's test extends this polite convention to machines:
If a machine acts as intelligently as a human being, then it is as intelligent as a human being.
One criticism of the Turing test is that it only measures the "humanness" of the machine's behavior, rather than the "intelligence" of the behavior. Since human behavior and intelligent behavior are not exactly the same thing, the test fails to measure intelligence. Stuart J. Russell and Peter Norvig write that "aeronautical engineering texts do not define the goal of their field as 'making machines that fly so exactly like pigeons that they can fool other pigeons'".
Intelligence as achieving goals
Twenty-first century AI research defines intelligence in terms of goal-directed behavior. It views intelligence as a set of problems that the machine is expected to solve – the more problems it can solve, and the better its solutions are, the more intelligent the program is. AI founder John McCarthy defined intelligence as "the computational part of the ability to achieve goals in the world."
Stuart Russell and Peter Norvig formalized this definition using abstract intelligent agents. An "agent" is something which perceives and acts in an environment. A "performance measure" defines what counts as success for the agent.
"If an agent acts so as to maximize the expected value of a performance measure based on past experience and knowledge then it is intelligent."
Definitions like this one try to capture the essence of intelligence. They have the advantage that, unlike the Turing test, they do not also test for unintelligent human traits such as making typing mistakes.
They have the disadvantage that they can fail to differentiate between "things that think" and "things that do not". By this definition, even a thermostat has a rudimentary intelligence.
Arguments that a machine can display general intelligence
The brain can be simulated
Hubert Dreyfus describes this argument as claiming that "if the nervous system obeys the laws of physics and chemistry, which we have every reason to suppose it does, then ... we ... ought to be able to reproduce the behavior of the nervous system with some physical device". This argument, first introduced as early as 1943 and vividly described by Hans Moravec in 1988,
is now associated with futurist Ray Kurzweil, who estimates that computer power will be sufficient for a complete brain simulation by the year 2029. A non-real-time simulation of a thalamocortical model that has the size of the human brain (1011 neurons) was performed in 2005, and it took 50 days to simulate 1 second of brain dynamics on a cluster of 27 processors.
Even AI's harshest critics (such as Hubert Dreyfus and John Searle) agree that a brain simulation is possible in theory.
However, Searle points out that, in principle, anything can be simulated by a computer; thus, bringing the definition to its breaking point leads to the conclusion that any process at all can technically be considered "computation". "What we wanted to know is what distinguishes the mind from thermostats and livers," he writes. Thus, merely simulating the functioning of a living brain would in itself be an admission of ignorance regarding intelligence and the nature of the mind, like trying to build a jet airliner by copying a living bird precisely, feather by feather, with no theoretical understanding of aeronautical engineering.
Human thinking is symbol processing
In 1963, Allen Newell and Herbert A. Simon proposed that "symbol manipulation" was the essence of both human and machine intelligence. They wrote:
"A physical symbol system has the necessary and sufficient means of general intelligent action."
This claim is very strong: it implies both that human thinking is a kind of symbol manipulation (because a symbol system is necessary for intelligence) and that machines can be intelligent (because a symbol system is sufficient for intelligence).
Another version of this position was described by philosopher Hubert Dreyfus, who called it "the psychological assumption":
"The mind can be viewed as a device operating on bits of information according to formal rules."
The "symbols" that Newell, Simon and Dreyfus discussed were word-like and high levelsymbols that directly correspond with objects in the world, such as <dog> and <tail>. Most AI programs written between 1956 and 1990 used this kind of symbol. Modern AI, based on statistics and mathematical optimization, does not use the high-level "symbol processing" that Newell and Simon discussed.
Arguments against symbol processing
These arguments show that human thinking does not consist (solely) of high level symbol manipulation. They do not show that artificial intelligence is impossible, only that more than symbol processing is required.
Gödelian anti-mechanist arguments
In 1931, Kurt Gödel proved with an incompleteness theorem that it is always possible to construct a "Gödel statement" that a given consistent formal system of logic (such as a high-level symbol manipulation program) could not prove. Despite being a true statement, the constructed Gödel statement is unprovable in the given system. (The truth of the constructed Gödel statement is contingent on the consistency of the given system; applying the same process to a subtly inconsistent system will appear to succeed, but will actually yield a false "Gödel statement" instead.) More speculatively, Gödel conjectured that the human mind can eventually correctly determine the truth or falsity of any well-grounded mathematical statement (including any possible Gödel statement), and that therefore the human mind's power is not reducible to a mechanism. Philosopher John Lucas (since 1961) and Roger Penrose (since 1989) have championed this philosophical anti-mechanist argument.
Gödelian anti-mechanist arguments tend to rely on the innocuous-seeming claim that a system of human mathematicians (or some idealization of human mathematicians) is both consistent (completely free of error) and believes fully in its own consistency (and can make all logical inferences that follow from its own consistency, including belief in its Gödel statement) . This is probably impossible for a Turing machine to do (see Halting problem); therefore, the Gödelian concludes that human reasoning is too powerful to be captured by a Turing machine, and by extension, any digital mechanical device.
However, the modern consensus in the scientific and mathematical community is that actual human reasoning is inconsistent; that any consistent "idealized version" H of human reasoning would logically be forced to adopt a healthy but counter-intuitive open-minded skepticism about the consistency of H (otherwise H is provably inconsistent); and that Gödel's theorems do not lead to any valid argument that humans have mathematical reasoning capabilities beyond what a machine could ever duplicate. This consensus that Gödelian anti-mechanist arguments are doomed to failure is laid out strongly in Artificial Intelligence: "any attempt to utilize (Gödel's incompleteness results) to attack the computationalist thesis is bound to be illegitimate, since these results are quite consistent with the computationalist thesis."
Stuart Russell and Peter Norvig agree that Gödel's argument does not consider the nature of real-world human reasoning. It applies to what can theoretically be proved, given an infinite amount of memory and time. In practice, real machines (including humans) have finite resources and will have difficulty proving many theorems. It is not necessary to be able to prove everything in order to be an intelligent person.
Less formally, Douglas Hofstadter, in his Pulitzer Prize winning book Gödel, Escher, Bach: An Eternal Golden Braid, states that these "Gödel-statements" always refer to the system itself, drawing an analogy to the way the Epimenides paradox uses statements that refer to themselves, such as "this statement is false" or "I am lying". But, of course, the Epimenides paradox applies to anything that makes statements, whether it is a machine or a human, even Lucas himself. Consider:
Lucas can't assert the truth of this statement.
This statement is true but cannot be asserted by Lucas. This shows that Lucas himself is subject to the same limits that he describes for machines, as are all people, and so Lucas's argument is pointless.
After concluding that human reasoning is non-computable, Penrose went on to controversially speculate that some kind of hypothetical non-computable processes involving the collapse of quantum mechanical states give humans a special advantage over existing computers. Existing quantum computers are only capable of reducing the complexity of Turing computable tasks and are still restricted to tasks within the scope of Turing machines. . By Penrose and Lucas's arguments, the fact that quantum computers are only able to complete Turing computable tasks implies that they cannot be sufficient for emulating the human mind. Therefore, Penrose seeks for some other process involving new physics, for instance quantum gravity which might manifest new physics at the scale of the Planck mass via spontaneous quantum collapse of the wave function. These states, he suggested, occur both within neurons and also spanning more than one neuron. However, other scientists point out that there is no plausible organic mechanism in the brain for harnessing any sort of quantum computation, and furthermore that the timescale of quantum decoherence seems too fast to influence neuron firing.
Dreyfus: the primacy of implicit skills
Hubert Dreyfus argued that human intelligence and expertise depended primarily on fast intuitive judgements rather than step-by-step symbolic manipulation, and argued that these skills would never be captured in formal rules.
Dreyfus's argument had been anticipated by Turing in his 1950 paper Computing machinery and intelligence, where he had classified this as the "argument from the informality of behavior." Turing argued in response that, just because we do not know the rules that govern a complex behavior, this does not mean that no such rules exist. He wrote: "we cannot so easily convince ourselves of the absence of complete laws of behaviour ... The only way we know of for finding such laws is scientific observation, and we certainly know of no circumstances under which we could say, 'We have searched enough. There are no such laws.'"
Russell and Norvig point out that, in the years since Dreyfus published his critique, progress has been made towards discovering the "rules" that govern unconscious reasoning. The situated movement in robotics research attempts to capture our unconscious skills at perception and attention. Computational intelligence paradigms, such as neural nets, evolutionary algorithms and so on are mostly directed at simulated unconscious reasoning and learning. Statistical approaches to AI can make predictions which approach the accuracy of human intuitive guesses. Research into commonsense knowledge has focused on reproducing the "background" or context of knowledge. In fact, AI research in general has moved away from high level symbol manipulation, towards new models that are intended to capture more of our intuitive reasoning.
Cognitive science and psychology eventually came to agree with Dreyfus' description of human expertise. Daniel Kahnemann and others developed a similar theory where they identified two "systems" that humans use to solve problems, which he called "System 1" (fast intuitive judgements) and "System 2" (slow deliberate step by step thinking).
Although Dreyfus' views have been vindicated in many ways, the work in cognitive science and in AI was in response to specific problems in those fields and was not directly influenced by Dreyfus. Historian and AI researcher Daniel Crevier wrote that "time has proven the accuracy and perceptiveness of some of Dreyfus's comments. Had he formulated them less aggressively, constructive actions they suggested might have been taken much earlier."
Can a machine have a mind, consciousness, and mental states?
This is a philosophical question, related to the problem of other minds and the hard problem of consciousness. The question revolves around a position defined by John Searle as "strong AI":
A physical symbol system can have a mind and mental states.
Searle distinguished this position from what he called "weak AI":
A physical symbol system can act intelligently.
Searle introduced the terms to isolate strong AI from weak AI so he could focus on what he thought was the more interesting and debatable issue. He argued that even if we assume that we had a computer program that acted exactly like a human mind, there would still be a difficult philosophical question that needed to be answered.
Neither of Searle's two positions are of great concern to AI research, since they do not directly answer the question "can a machine display general intelligence?" (unless it can also be shown that consciousness is necessary for intelligence). Turing wrote "I do not wish to give the impression that I think there is no mystery about consciousness… [b]ut I do not think these mysteries necessarily need to be solved before we can answer the question [of whether machines can think]." Russell and Norvig agree: "Most AI researchers take the weak AI hypothesis for granted, and don't care about the strong AI hypothesis."
There are a few researchers who believe that consciousness is an essential element in intelligence, such as Igor Aleksander, Stan Franklin, Ron Sun, and Pentti Haikonen, although their definition of "consciousness" strays very close to "intelligence". (See artificial consciousness.)
Before we can answer this question, we must be clear what we mean by "minds", "mental states" and "consciousness".
Consciousness, minds, mental states, meaning
The words "mind" and "consciousness" are used by different communities in different ways. Some new age thinkers, for example, use the word "consciousness" to describe something similar to Bergson's "élan vital": an invisible, energetic fluid that permeates life and especially the mind. Science fiction writers use the word to describe some essential property that makes us human: a machine or alien that is "conscious" will be presented as a fully human character, with intelligence, desires, will, insight, pride and so on. (Science fiction writers also use the words "sentience", "sapience", "self-awareness" or "ghost"—as in the Ghost in the Shell manga and anime series—to describe this essential human property). For others , the words "mind" or "consciousness" are used as a kind of secular synonym for the soul.
For philosophers, neuroscientists and cognitive scientists, the words are used in a way that is both more precise and more mundane: they refer to the familiar, everyday experience of having a "thought in your head", like a perception, a dream, an intention or a plan, and to the way we see something, know something, mean something or understand something. "It's not hard to give a commonsense definition of consciousness" observes philosopher John Searle. What is mysterious and fascinating is not so much what it is but how it is: how does a lump of fatty tissue and electricity give rise to this (familiar) experience of perceiving, meaning or thinking?
Philosophers call this the hard problem of consciousness. It is the latest version of a classic problem in the philosophy of mind called the "mind-body problem". A related problem is the problem of meaning or understanding (which philosophers call "intentionality"): what is the connection between our thoughts and what we are thinking about (i.e. objects and situations out in the world)? A third issue is the problem of experience (or "phenomenology"): If two people see the same thing, do they have the same experience? Or are there things "inside their head" (called "qualia") that can be different from person to person?
Neurobiologists believe all these problems will be solved as we begin to identify the neural correlates of consciousness: the actual relationship between the machinery in our heads and its collective properties; such as the mind, experience and understanding. Some of the harshest critics of artificial intelligence agree that the brain is just a machine, and that consciousness and intelligence are the result of physical processes in the brain. The difficult philosophical question is this: can a computer program, running on a digital machine that shuffles the binary digits of zero and one, duplicate the ability of the neurons to create minds, with mental states (like understanding or perceiving), and ultimately, the experience of consciousness?
Arguments that a computer cannot have a mind and mental states
Searle's Chinese room
John Searle asks us to consider a thought experiment: suppose we have written a computer program that passes the Turing test and demonstrates general intelligent action. Suppose, specifically that the program can converse in fluent Chinese. Write the program on 3x5 cards and give them to an ordinary person who does not speak Chinese. Lock the person into a room and have him follow the instructions on the cards. He will copy out Chinese characters and pass them in and out of the room through a slot. From the outside, it will appear that the Chinese room contains a fully intelligent person who speaks Chinese. The question is this: is there anyone (or anything) in the room that understands Chinese? That is, is there anything that has the mental state of understanding, or which has conscious awareness of what is being discussed in Chinese? The man is clearly not aware. The room cannot be aware. The cards certainly are not aware. Searle concludes that the Chinese room, or any other physical symbol system, cannot have a mind.
Searle goes on to argue that actual mental states and consciousness require (yet to be described) "actual physical-chemical properties of actual human brains." He argues there are special "causal properties" of brains and neurons that gives rise to minds: in his words "brains cause minds."
Related arguments: Leibniz' mill, Davis's telephone exchange, Block's Chinese nation and Blockhead
Gottfried Leibniz made essentially the same argument as Searle in 1714, using the thought experiment of expanding the brain until it was the size of a mill. In 1974, Lawrence Davis imagined duplicating the brain using telephone lines and offices staffed by people, and in 1978 Ned Block envisioned the entire population of China involved in such a brain simulation. This thought experiment is called "the Chinese Nation" or "the Chinese Gym". Ned Block also proposed his Blockhead argument, which is a version of the Chinese room in which the program has been re-factored into a simple set of rules of the form "see this, do that", removing all mystery from the program.
Responses to the Chinese room
Responses to the Chinese room emphasize several different points.
The systems reply and the virtual mind reply: This reply argues that the system, including the man, the program, the room, and the cards, is what understands Chinese. Searle claims that the man in the room is the only thing which could possibly "have a mind" or "understand", but others disagree, arguing that it is possible for there to be two minds in the same physical place, similar to the way a computer can simultaneously "be" two machines at once: one physical (like a Macintosh) and one "virtual" (like a word processor).
Speed, power and complexity replies: Several critics point out that the man in the room would probably take millions of years to respond to a simple question, and would require "filing cabinets" of astronomical proportions. This brings the clarity of Searle's intuition into doubt.
Robot reply: To truly understand, some believe the Chinese Room needs eyes and hands. Hans Moravec writes: "If we could graft a robot to a reasoning program, we wouldn't need a person to provide the meaning anymore: it would come from the physical world."
Brain simulator reply: What if the program simulates the sequence of nerve firings at the synapses of an actual brain of an actual Chinese speaker? The man in the room would be simulating an actual brain. This is a variation on the "systems reply" that appears more plausible because "the system" now clearly operates like a human brain, which strengthens the intuition that there is something besides the man in the room that could understand Chinese.
Other minds reply and the epiphenomena reply: Several people have noted that Searle's argument is just a version of the problem of other minds, applied to machines. Since it is difficult to decide if people are "actually" thinking, we should not be surprised that it is difficult to answer the same question about machines.
A related question is whether "consciousness" (as Searle understands it) exists. Searle argues that the experience of consciousness cannot be detected by examining the behavior of a machine, a human being or any other animal. Daniel Dennett points out that natural selection cannot preserve a feature of an animal that has no effect on the behavior of the animal, and thus consciousness (as Searle understands it) cannot be produced by natural selection. Therefore, either natural selection did not produce consciousness, or "strong AI" is correct in that consciousness can be detected by suitably designed Turing test.
Is thinking a kind of computation?
The computational theory of mind or "computationalism" claims that the relationship between mind and brain is similar (if not identical) to the relationship between a running program (software) and a computer (hardware). The idea has philosophical roots in Hobbes (who claimed reasoning was "nothing more than reckoning"), Leibniz (who attempted to create a logical calculus of all human ideas), Hume (who thought perception could be reduced to "atomic impressions") and even Kant (who analyzed all experience as controlled by formal rules). The latest version is associated with philosophers Hilary Putnam and Jerry Fodor.
This question bears on our earlier questions: if the human brain is a kind of computer then computers can be both intelligent and conscious, answering both the practical and philosophical questions of AI. In terms of the practical question of AI ("Can a machine display general intelligence?"), some versions of computationalism make the claim that (as Hobbes wrote):
Reasoning is nothing but reckoning.
In other words, our intelligence derives from a form of calculation, similar to arithmetic. This is the physical symbol system hypothesis discussed above, and it implies that artificial intelligence is possible. In terms of the philosophical question of AI ("Can a machine have mind, mental states and consciousness?"), most versions of computationalism claim that (as Stevan Harnad characterizes it):
Mental states are just implementations of (the right) computer programs.
This is John Searle's "strong AI" discussed above, and it is the real target of the Chinese room argument (according to Harnad).
Other related questions
Can a machine have emotions?
If "emotions" are defined only in terms of their effect on behavior or on how they function inside an organism, then emotions can be viewed as a mechanism that an intelligent agent uses to maximize the utility of its actions. Given this definition of emotion, Hans Moravec believes that "robots in general will be quite emotional about being nice people". Fear is a source of urgency. Empathy is a necessary component of good human computer interaction. He says robots "will try to please you in an apparently selfless manner because it will get a thrill out of this positive reinforcement. You can interpret this as a kind of love." Daniel Crevier writes "Moravec's point is that emotions are just devices for channeling behavior in a direction beneficial to the survival of one's species."
Can a machine be self-aware?
"Self-awareness", as noted above, is sometimes used by science fiction writers as a name for the essential human property that makes a character fully human. Turing strips away all other properties of human beings and reduces the question to "can a machine be the subject of its own thought?" Can it think about itself? Viewed in this way, a program can be written that can report on its own internal states, such as a debugger.
Can a machine be original or creative?
Turing reduces this to the question of whether a machine can "take us by surprise" and argues that this is obviously true, as any programmer can attest. He notes that, with enough storage capacity, a computer can behave in an astronomical number of different ways. It must be possible, even trivial, for a computer that can represent ideas to combine them in new ways. (Douglas Lenat's Automated Mathematician, as one example, combined ideas to discover new mathematical truths.) Kaplan and Haenlein suggest that machines can display scientific creativity, while it seems likely that humans will have the upper hand where artistic creativity is concerned.
In 2009, scientists at Aberystwyth University in Wales and the U.K's University of Cambridge designed a robot called Adam that they believe to be the first machine to independently come up with new scientific findings. Also in 2009, researchers at Cornell developed Eureqa, a computer program that extrapolates formulas to fit the data inputted, such as finding the laws of motion from a pendulum's motion.
Can a machine be benevolent or hostile?
This question (like many others in the philosophy of artificial intelligence) can be presented in two forms. "Hostility" can be defined in terms function or behavior, in which case "hostile" becomes synonymous with "dangerous". Or it can be defined in terms of intent: can a machine "deliberately" set out to do harm? The latter is the question "can a machine have conscious states?" (such as intentions) in another form.
The question of whether highly intelligent and completely autonomous machines would be dangerous has been examined in detail by futurists (such as the Machine Intelligence Research Institute). The obvious element of drama has also made the subject popular in science fiction, which has considered many differently possible scenarios where intelligent machines pose a threat to mankind; see Artificial intelligence in fiction.
One issue is that machines may acquire the autonomy and intelligence required to be dangerous very quickly. Vernor Vinge has suggested that over just a few years, computers will suddenly become thousands or millions of times more intelligent than humans. He calls this "the Singularity". He suggests that it may be somewhat or possibly very dangerous for humans. This is discussed by a philosophy called Singularitarianism.
In 2009, academics and technical experts attended a conference to discuss the potential impact of robots and computers and the impact of the hypothetical possibility that they could become self-sufficient and able to make their own decisions. They discussed the possibility and the extent to which computers and robots might be able to acquire any level of autonomy, and to what degree they could use such abilities to possibly pose any threat or hazard. They noted that some machines have acquired various forms of semi-autonomy, including being able to find power sources on their own and being able to independently choose targets to attack with weapons. They also noted that some computer viruses can evade elimination and have achieved "cockroach intelligence". They noted that self-awareness as depicted in science-fiction is probably unlikely, but that there were other potential hazards and pitfalls.
Some experts and academics have questioned the use of robots for military combat, especially when such robots are given some degree of autonomous functions. The US Navy has funded a report which indicates that as military robots become more complex, there should be greater attention to implications of their ability to make autonomous decisions.
The President of the Association for the Advancement of Artificial Intelligence has commissioned a study to look at this issue. They point to programs like the Language Acquisition Device which can emulate human interaction.
Some have suggested a need to build "Friendly AI", a term coined by Eliezer Yudkowsky, meaning that the advances which are already occurring with AI should also include an effort to make AI intrinsically friendly and humane.
Can a machine imitate all human characteristics?
Turing said "It is customary ... to offer a grain of comfort, in the form of a statement that some peculiarly human characteristic could never be imitated by a machine. ... I cannot offer any such comfort, for I believe that no such bounds can be set."
Turing noted that there are many arguments of the form "a machine will never do X", where X can be many things, such as:
Be kind, resourceful, beautiful, friendly, have initiative, have a sense of humor, tell right from wrong, make mistakes, fall in love, enjoy strawberries and cream, make someone fall in love with it, learn from experience, use words properly, be the subject of its own thought, have as much diversity of behaviour as a man, do something really new.
Turing argues that these objections are often based on naive assumptions about the versatility of machines or are "disguised forms of the argument from consciousness". Writing a program that exhibits one of these behaviors "will not make much of an impression." All of these arguments are tangential to the basic premise of AI, unless it can be shown that one of these traits is essential for general intelligence.
Can a machine have a soul?
Finally, those who believe in the existence of a soul may argue that "Thinking is a function of man's immortal soul." Alan Turing called this "the theological objection". He writes:
In attempting to construct such machines we should not be irreverently usurping His power of creating souls, any more than we are in the procreation of children: rather we are, in either case, instruments of His will providing mansions for the souls that He creates.The discussion on the topic has been reignited as a result of recent claims made by Google's LaMDA artificial intelligence system that it is sentient and had a "soul".
LaMDA (Language Model for Dialogue Applications) is an artificial intelligence system that creates chatbots—AI robots designed to communicate with humans—by gathering vast amounts of text from the internet and using algorithms to respond to queries in the most fluid and natural way possible.
The transcripts of conversations between scientists and LaMDA reveal that the AI system excels at this, providing answers to challenging topics about the nature of emotions, generating Aesop-style fables on the moment, and even describing its alleged fears. Pretty much all philosophers doubt LaMDA's sentience.
Views on the role of philosophy
Some scholars argue that the AI community's dismissal of philosophy is detrimental. In the Stanford Encyclopedia of Philosophy, some philosophers argue that the role of philosophy in AI is underappreciated. Physicist David Deutsch argues that without an understanding of philosophy or its concepts, AI development would suffer from a lack of progress.
Conferences and literature
The main conference series on the issue is "Philosophy and Theory of AI" (PT-AI), run by Vincent C. Müller.
The main bibliography on the subject, with several sub-sections, is on PhilPapers.
A recent survey for Philosophy of AI is Müller (2023).
See also
AI takeover
Artificial brain
Artificial consciousness
Artificial intelligence
Artificial neural network
Chatbot
Computational theory of mind
Computing Machinery and Intelligence
Existential risk from artificial general intelligence
Functionalism
Hubert Dreyfus's views on artificial intelligence
Multi-agent system
Philosophy of computer science
Philosophy of information
Philosophy of mind
Physical symbol system
Simulated reality
Superintelligence: Paths, Dangers, Strategies
Synthetic intelligence
Wireheading
Notes
References
Works cited
Adam, Alison (1989). Artificial Knowing: Gender and the Thinking Machine. Routledge & CRC Press.
Benjamin, Ruha (2019). Race After Technology: Abolitionist Tools for the New Jim Code. Wiley.
,
Bryson, Joanna (2019). The Artificial Intelligence of the Ethics of Artificial Intelligence: An Introductory Overview for Law and Regulation, p. 34
Crawford, Kate (2021). Atlas of AI: Power, Politics, and the Planetary Costs of Artificial Intelligence. Yale University Press
Haraway, Donna (1985). A Cyborg Manifesto
Malabou, Catherine (2019). Morphing Intelligence: From IQ Measurement to Artificial Brains. (C. Shread, Trans.). Columbia University Press
c
Rescorla, Michael, "The Computational Theory of Mind", in:Edward N. Zalta (ed.), The Stanford Encyclopedia of Philosophy (Fall 2020 Edition)
Philosophy of science
Philosophy of technology
Artificial
Open problems
Articles containing video clips | Philosophy of artificial intelligence | [
"Technology"
] | 7,521 | [
"Philosophy of technology",
"Science and technology studies"
] |
2,958,034 | https://en.wikipedia.org/wiki/Supply%20network%20operations | Supply network operations or supply chain operations involve the synchronized execution of compliant manufacturing and logistics processes across a dynamically reconfigurable supply network to profitably meet demand.
References
Supply chain management
Business process
Transport operations
Global business organization | Supply network operations | [
"Physics"
] | 47 | [
"Physical systems",
"Transport",
"Transport operations"
] |
2,958,127 | https://en.wikipedia.org/wiki/Uttarayana | The term Uttarāyaṇa (commonly Uttarayanam) is derived from two different Sanskrit words – "uttaram" (North) and "ayanam" (movement) – thus indicating the northward movement of the Sun. In the Gregorian calendar, this pertains to the "actual movement of the sun with respect to the earth." Also known as the six month period that occurs between the winter solstice and summer solstice (approximately 20 December - 20 June). According to the Indian solar calendar, it refers to the movement of the Sun through the zodiac. This difference is because the solstices continually precess at a rate of 50 arcseconds per year due to the precession of the equinoxes, i.e. this difference is the difference between the sidereal and tropical zodiacs. The Surya Siddhanta bridges this difference by juxtaposing the four solstitial and equinoctial points with four of the twelve boundaries of the rashis.
The complement of Uttarayana is Dakshinayana (the southward movement of the Sun). It is the period between Karka Sankranti and Makara Sankranti as per the sidereal zodiac and between the summer solstice and winter solstice as per the tropical zodiac.
Difference between Uttarayana and Makara Sankranti
There is a common misconception that Makara Sankranti marks the beginning of Uttarayana. This is because at one point in time Sayana and Nirayana zodiac were the same. Every year sidereal and tropical equinoxes slide by 50 seconds due to axial precession, giving birth to Ayanamsha and causing Makara Sankranti to slide further. When equinox slides it will increase ayanamsha and Makara Sankranti will also slide. This misconception continues as there is not much difference between actual Uttarayana date which occurs a day after winter solstice (of Dec 21) when the Sun makes the northward journey, and 14 January. However, the difference will be significant as equinoxes slide further. In 272 CE, Makara Sankranti was on 21 December. In 1000 CE, Makara Sankranti was on 31 December and now it falls on January 14. After 9000 years, Makara Sankranti will be in June. Then Makara Sankranti would mark the beginning of Dakshinayana. However Makara Sankranti still holds importance in Hindu rituals. All Drika Panchanga makers like mypanchang.com, datepanchang, janmabhumi panchang, rashtriya panchang and Vishuddha Siddhanta Panjika use the position of the tropical Sun to determine Uttarayana and Dakshinayana.
Uttarayana in various treatises
Surya Siddhanta
Mayasura, the composer of Surya Siddhanta, defines Uttarayana, at the time of composition, as the period between the Makara Sankranti (which currently occurs around January 14) and Karka Sankranti (which currently occurs around July 16). Lātadeva describes this as half revolutions of the Sun, using the terms Uttarayana and Dakshinayana to describe the "northern and southern progress" respectively. Bal Gangadhar Tilak, a scholar and mathematician, proposes an alternative, early vedic definition of Uttarayana as starting from Vernal Equinox and ending with Autumnal Equinox. This definition interprets the term "Uttara Ayana" as "northern movement" instead of "northward movement", i.e. as the movement of the Earth in the region North of the Equator. In support of this proposal, he points to another tradition that the Uttarayana is considered the daytime of the Gods residing at the North Pole which tradition makes sense only if we define Uttarayana as the period between the Vernal and Autumnal equinoxes (when there is Midnight Sun at the North Pole). Conversely, Dakshinaya is defined as the period between the Autumnal and Vernal Equinoxes, when there is midnight sun at the South Pole. This period is also referred to as Pitrayana (with the Pitrus (i.e. ancestors) being placed at the South Pole).
Drik Siddhanta
This festival is currently celebrated on the 14th or 15 January but due to axial precession of the Earth it will continue to shift away from the actual season. The season occurs based on tropical sun (without ayanamsha). The Earth revolves around Sun with a tilt of 23.44 degrees. When the tilt is facing the Sun it is defined as summer and when the tilt is away from the Sun it is called winter. That is the reason when there is summer north of the equator, it will be winter south of the equator. Because of this tilt, the Sun appears to travel north and south of the equator. This motion of the Sun transitioning from south to north is called Uttarayana (the Sun is moving towards north). Once the Sun reaches north, it begins moving south and is called Dakshinayana – the Sun is moving towards south. This causes seasons which are dependent on equinoxes and solstices.
Hindu Scriptures
Uttarayana is referred to as the day of new good healthy wealthy beginning. In the Mahabharata, this day marks the death of Bhishma. Bhishma had the ability to choose the time of his death and although mortally wounded in war, he chose to delay his death until uttarayan. According to the Bhagavad Gita, a Hindu scripture, those who die when the Sun is on its northward course (from south to north) attain nirvana. This explains the choice made by Bhishma to wait until Uttarayana to die.
According to the Hindu tradition the six month period of Uttarayana is equivalent to a single day of the Gods, while the six month period of Dakshinayana is equal to a single night of the Gods. Thus a year of twelve months is single day of the Gods. This refers to the six months of single day at the North pole and concurrent six months of night at the south pole.
Rituals
During the Uttarayana, devotees often undertake certain rituals to benefit during the auspicious time. Devotees often take part in pilgrimages to bathe in Prayag, where the Yamuna, Ganga and Saraswati rivers meet.
Pongal is celebrated as a harvest festival in the southern states of India like Tamil Nadu. Although rituals and customs may vary, it is generally celebrated as a four-day festival. On the first day, unwanted household items are discarded and burned in bonfires to symbolize starting anew. The second day, people dress in new clothes and prepare pongal, a sweet dish that is made of rice, milk and jaggery, and offer it to Surya, the Hindu sun deity. On the third day, cattle are worshipped because they are seen as a symbol of prosperity. And, on the last day, some regions host bull-fighting and farmers offer prayers for the new, fresh harvest.
Known as Lori in the northern states, children go door-to-door asking for sweets and money, and in the evening, people gather around huge bonfires to sing, dance, and make offerings to Agni, the fire deity, for future prosperity. Traditional dishes made from flatbread and mustard leaves are shared with offerings of sesame brittle, peanuts, popcorn, and jaggery. It is celebrated in other North Indian states like Haryana, Delhi, and Himachal Pradesh.
References
External links
Animated illustration of Uttarayana and Dakshinayana
Hindu astronomy
Hindu calendar
Articles containing video clips
Summer solstice
Winter solstice | Uttarayana | [
"Astronomy"
] | 1,602 | [
"Time in astronomy",
"Astronomical events",
"Winter solstice",
"Summer solstice"
] |
2,959,101 | https://en.wikipedia.org/wiki/Diethanolamine | Diethanolamine, often abbreviated as DEA or DEOA, is an organic compound with the formula HN(CH2CH2OH)2. Pure diethanolamine is a white solid at room temperature, but its tendencies to absorb water and to supercool often results in it being found in a colorless, viscous liquid state. Diethanolamine is polyfunctional, being a secondary amine and a diol. Like other organic amines, diethanolamine acts as a weak base. Reflecting the hydrophilic character of the secondary amine and hydroxyl groups, DEA is soluble in water. Amides prepared from DEA are often also hydrophilic. In 2013, the chemical was classified by the International Agency for Research on Cancer as "possibly carcinogenic to humans" (Group 2B).
Production
The reaction of ethylene oxide with aqueous ammonia first produces ethanolamine:
C2H4O + NH3 → H2NCH2CH2OH
which reacts with a second and third equivalent of ethylene oxide to give DEA and triethanolamine:
C2H4O + H2NCH2CH2OH → HN(CH2CH2OH)2
C2H4O + HN(CH2CH2OH)2 → N(CH2CH2OH)3
About 300M kg are produced annually in this way. The ratio of the products can be controlled by changing the stoichiometry of the reactants.
Uses
DEA is used as a surfactant and a corrosion inhibitor. It is used to remove hydrogen sulfide and carbon dioxide from natural gas.
Diethanolamine is widely used in the preparation of diethanolamides and diethanolamine salts of long-chain fatty acids that are formulated into soaps and surfactants used in liquid laundry and dishwashing detergents, cosmetics, shampoos and hair conditioners. In oil refineries, a DEA in water solution is commonly used to remove hydrogen sulfide from sour gas. It has an advantage over a similar amine, ethanolamine, in that a higher concentration may be used for the same corrosion potential. This allows refiners to scrub hydrogen sulfide at a lower circulating amine rate with less overall energy usage.
DEA is a chemical feedstock used in the production of morpholine.
Amides derived from DEA and fatty acids, known as diethanolamides, are amphiphilic.
The reaction of 2-chloro-4,5-diphenyloxazole with DEA gave rise to ditazole. The reaction of DEA and isobutyraldehyde with water removed produces an oxazolidine.
Commonly used ingredients that may contain DEA
DEA is used in the production of diethanolamides, which are common ingredients in cosmetics and shampoos added to confer a creamy texture and foaming action. Consequently, some cosmetics that include diethanolamides as ingredients contain DEA. Some of the most commonly used diethanolamides include:
Cocamide DEA
DEA-Cetyl Phosphate
DEA Oleth-3 Phosphate
Lauramide DEA
Myristamide DEA
Oleamide DEA
Safety and environment
DEA is a potential skin irritant in workers sensitized by exposure to water-based metalworking fluids.
DEA has potential toxicity properties for aquatic species.
References
External links
Chemical safety card for DEA
CDC - NIOSH Pocket Guide to Chemical Hazards
Toxicology and Carcinogenesis Studies
Brief technical specification of diethanolamine
Brief technical specification of diethanolamine pure
Diols
Endocrine disruptors
IARC Group 2B carcinogens
Secondary amines
Ethanolamines | Diethanolamine | [
"Chemistry"
] | 756 | [
"Endocrine disruptors"
] |
2,959,305 | https://en.wikipedia.org/wiki/Ascending%20colon | In the anatomy of humans and homologous primates, the ascending colon is the part of the colon located between the cecum and the transverse colon.
Characteristics and structure
The ascending colon is smaller in calibre than the cecum from where it starts. It passes upward, opposite the colic valve, to the under surface of the right lobe of the liver, on the right of the gall-bladder, where it is lodged in a shallow depression, the colic impression; here it bends abruptly forward and to the left, forming the right colic flexure (hepatic) where it becomes the transverse colon.
It is retained in contact with the posterior wall of the abdomen by the peritoneum, which covers its anterior surface and sides, its posterior surface being connected by loose areolar tissue with the iliacus, quadratus lumborum, aponeurotic origin of transversus abdominis, and with the front of the lower and lateral part of the right kidney.
Sometimes the peritoneum completely invests it and forms a distinct but narrow mesocolon.
It is in relation, in front, with the convolutions of the ileum and the abdominal walls.
Parasympathetic innervation to the ascending colon is supplied by the vagus nerve. Sympathetic innervation is supplied by the thoracic splanchnic nerves.
Location
The ascending colon is on the right side of the body (barring any malformations). The term right colon is hypernymous to ascending colon in precise use; many casual mentions of the right colon chiefly concern the ascending colon.
Additional images
See also
Descending colon
References
External links
- "The large intestine."
()
Large intestine
Digestive system | Ascending colon | [
"Biology"
] | 361 | [
"Digestive system",
"Organ systems"
] |
2,959,451 | https://en.wikipedia.org/wiki/233%20%28number%29 | 233 (two hundred [and] thirty-three) is the natural number following 232 and preceding 234.
Additionally:
233 is a prime number
233 is a Sophie Germain prime, a Pillai prime, and a Ramanujan prime
It is a Fibonacci number, one of the Fibonacci primes
There are exactly 233 maximal planar graphs with ten vertices, and 233 connected topological spaces with four points
References
Integers | 233 (number) | [
"Mathematics"
] | 88 | [
"Mathematical objects",
"Number stubs",
"Elementary mathematics",
"Integers",
"Numbers"
] |
2,959,462 | https://en.wikipedia.org/wiki/Ekran | For the Soviet animation studio see page Studio Ekran
Ekran (, meaning "Screen") was a Soviet-Russian type of geostationary satellite, developed for a national system of Direct-To-Home television. The first satellite of Ekran series was launched on 26 October 1976. Each satellite in the Ekran series was designed to provide one TV and two radio program channels to cable TV systems throughout the USSR and to individual home receivers in northern Siberia. Ekran's downlink is in the Ultra high frequency (UHF) range.
Early Ekran satellites used orbital positions in the range from 48° East to 95° East, but recent Ekran, including the current Ekran 20, have been stationed at 99° East. These 3-axis stabilized satellites carry a single 24 MHz, 200 watts transponder, feeding a 28 dB gain antenna transmitting on right-hand circular polarization to produce in Siberia in the range 50 to 55 dBW at 714 MHz. The corresponding feeder link uses left-hand circular polarization at 6200 MHz. Therefore, almost every householder could receive the TV signal at home from Ekran's transponder using a simple Yagi–Uda antenna. There were also various kinds of collective or individual satellite receivers, such as Ekran-KR10 and Ekran-KR01. Latest version of the receiver represents a simple individual TV set-top box itself. A modified version of Ekran was called Ekran-M. Ekran satellites have been replaced by improved geostationary craft for DBS, such as Gorizont, Gals, and Ekspress.
On 23 June 1978, the Ekran-2 spacecraft exploded due to a catastrophic discharge of its battery, contributing to the increase in space debris in the Geostationary orbit. On 1 February 2009, the last satellite from the Ekran series, Ekran-M at 99° East, stopped transmitting.
References
External links
Ekran satellite
Ekran satellite: a short history of development
Ekran-M
Communication satellites: Voices from Space - in Russian
Experiments of amateur Direct-To-Home reception of TV signal from Ekran satellite (included some photos)
Pacific Telecommunications Review
Communications satellites
Earth observation satellites of the Soviet Union
Television in the Soviet Union
Satellite television
Communications satellites of the Soviet Union
Satellites using the KAUR bus
Spacecraft that broke apart in space | Ekran | [
"Technology"
] | 479 | [
"Space debris",
"Spacecraft that broke apart in space"
] |
2,959,821 | https://en.wikipedia.org/wiki/Direct%20simulation%20Monte%20Carlo | Direct simulation Monte Carlo (DSMC) method uses probabilistic Monte Carlo simulation to solve the Boltzmann equation for finite Knudsen number fluid flows.
The DSMC method was proposed by Graeme Bird, emeritus professor of aeronautics, University of Sydney. DSMC is a numerical method for modeling rarefied gas flows, in which the mean free path of a molecule is of the same order (or greater) than a representative physical length scale (i.e. the Knudsen number Kn is greater than 1). In supersonic and hypersonic flows rarefaction is characterized by Tsien's parameter, which is equivalent to the product of Knudsen number and Mach number (KnM) or M/Re, where Re is the Reynolds number. In these rarefied flows, the Navier-Stokes equations can be inaccurate. The DSMC method has been extended to model continuum flows (Kn < 1) and the results can be compared with Navier Stokes solutions.
The DSMC method models fluid flows using probabilistic simulation molecules to solve the Boltzmann equation. Molecules are moved through a simulation of physical space in a realistic manner that is directly coupled to physical time such that unsteady flow characteristics can be modeled. Intermolecular collisions and molecule-surface collisions are calculated using probabilistic, phenomenological models. Common molecular models include the hard sphere model, the variable hard sphere (VHS) model, and the variable soft sphere (VSS) model. Various collision models are presented in.
Currently, the DSMC method has been applied to the solution of flows ranging from estimation of the Space Shuttle re-entry aerodynamics to the modeling of microelectromechanical systems (MEMS).
DSMC Algorithm
The direct simulation Monte Carlo algorithm is like molecular dynamics in that the state of
the system is given by the positions and velocities of the
particles, , for .
Unlike molecular dynamics, each particle in a DSMC simulation represents molecules in
the physical system that have roughly the same position and velocity.
This allows DSMC to rescale length and time for the modeling of macroscopic systems (e.g., atmospheric entry).
Specifically, the system volume is , where is the number
density and each collision between simulation particles represents collisions
among molecules in the physical system.
As a rule of thumb there should be 20 or more particles per cubic mean free path
for accurate results.
The evolution of the system is integrated in time steps, , which are
typically on the order of the mean collision time for a particle.
At each time step all the particles are moved and then a random set of pairs collide.
In the absence of external fields (e.g., gravity) the particles move ballistically as
.
Any particle that reaches a boundary or a surface has its position and velocity reset accordingly
(e.g., periodic boundary conditions).
After all the particles have moved, they are sorted into cells and some are randomly selected to collide.
based on probabilities and collision rates obtained from the kinetic theory of gases.
After the velocities of all colliding particles have been reset, statistical sampling is performed and then
the process is repeated for the next time step.
Collisions
On each timestep the particles are sorted into spatial cells and only particles in the same cell
are allowed to collide. Typically the dimension of a cell is no larger than a mean free path.
All pairs of particles in a cell are candidate collision partners, regardless of their actual trajectories.
The details of how collisions are calculated in DSMC depend on the molecular interaction model;
here we take the hard spheres model, which is the simplest.
In the hard spheres model, the collision probability for the pair of particles, and , is
proportional to their relative speed,
where is the number of particles in the cell and the summations are over particles within the cell.
Because of the double sum in the denominator it can be computationally expensive to use this collision probability directly.
Instead, the following rejection sampling scheme can be used to select collision pairs:
A pair of candidate particles, and , is chosen at random and their relative speed, , is computed.
The pair is accepted as collision partners if , where is the maximum relative speed in the cell and is a uniform deviate in [0, 1).
If the pair is accepted, the collision is processed; the velocities of the particles are reset but positions are unchanged.
After the collision is processed or if the pair is rejected, return to step 1.
This procedure is correct even if the value
of is overestimated, although it is less efficient
in the sense that more candidates are rejected.
After the collision pair is chosen, their post-collision velocities,
and , are evaluated.
Writing the relative velocity in terms of spherical angles, and
these angles are selected by a Monte Carlo process with distributions given by the collision model.
For the hard spheres model these angles are uniformly distributed over the unit sphere.
The azimuthal angle is uniformly distributed between 0 and , so it is selected as
where is a uniform deviate in [0, 1).
The polar angle is distributed according to the probability density,
Using the change of variable , we have so
The post-collision velocities are set as
Note that by conservation of linear momentum and energy the center of mass velocity
and the relative speed are unchanged in a collision. That is,
and
This process is repeated for every pair of colliding particles.
From the collision frequency, , given by kinetic theory the total
number of hard sphere collisions in a cell during a time is
where is the particle diameter and is the volume of the cell.
Since collision candidates go through a rejection sampling procedure
the ratio of total accepted to total candidates for hard sphere particles is
The number of collision candidates selected in a cell over a time step is
This approach for determining the number of collisions is known as the No-Time-Counter (NTC) method.
If is set excessively high then the algorithm processes the same number of collisions (on average)
but the simulation is inefficient because many candidates are rejected.
References
External links
Direct Simulation Monte Carlo Method: Visual Simulation Programs created by GA Bird.
DSMC Demo Applet by Greg Khanlarov
Course material on DSMC (part of Computational Physics tutorial by Franz J. Vesely, University of Vienna)
Course material on DSMC and recent developments (given at IPAM UCLA by Lorenzo Pareschi, University of Ferrara)
Monte Carlo methods
Statistical mechanics | Direct simulation Monte Carlo | [
"Physics"
] | 1,334 | [
"Monte Carlo methods",
"Statistical mechanics",
"Computational physics"
] |
2,959,966 | https://en.wikipedia.org/wiki/Chondrodite | Chondrodite is a nesosilicate mineral with formula . Although it is a fairly rare mineral, it is the most frequently encountered member of the humite group of minerals. It is formed in hydrothermal deposits from locally metamorphosed dolomite. It is also found associated with skarn and serpentinite.
It was discovered in 1817 at Pargas in Finland, and named from the Greek for "granule", which is a common habit for this mineral.
Formula
is the end member formula as given by the International Mineralogical Association, molar mass 351.6 g. There is usually some OH in the F sites, however, and Fe and Ti can substitute for Mg, so the formula for the naturally occurring mineral is better written .
Structure
The chondrodite structure is based on a slightly distorted hexagonal close packed array of anions O, OH and F with metal ions in the octahedral sites resulting in zigzag chains of octahedra. Chains are staggered so that none of the independent tetrahedral sites occupied by Si has OH or F corners. Half of the octahedral sites are filled by divalent cations, principally Mg, and one tenth of the tetrahedral sites are filled by Si. There are three distinct octahedra in the array: Fe is ordered in the M1 sites but not in the larger M2 and smaller M3 sites. Ti is ordered in the M3 positions, which are the smallest, but Ti concentration appears never to exceed 0.5 atoms Ti per formula unit in natural specimens. In the humite series Mg2+ is replaced by Fe2+, Mn2+, Ca2+ and Zn2+ in that order of abundance, though Mg2+ always predominates.
Unit cell
Space group: P21/b
Unit cell parameters:
Synthetic F end member a = 7.80 Å, b = 4.75 Å, c = 10.27 Å, beta = 109.2o.
Synthetic OH end member a = 7.914 Å, b = 4.752 Å, c = 10.350 Å, beta = 108.71o.
Natural chondrodite has a = 7.867 to 7.905 Å, b = 4.727 to 4.730 Å, c = 10.255 to 10.318 Å, beta = 109.0o to 109.33o.
Z = 2.
Color
Chondrodite is yellow, orange, red or brown, or rarely colorless, but zoning of different color intensity is common, and intergrown plates of chondrodite, humite, clinohumite, forsterite and monticellite have been reported.
Optical properties
Chondrodite is biaxial(+), with refractive indices variously reported as nα = 1.592 – 1.643, nβ = 1.602 – 1.655, nγ = 1.619 – 1.675, birefringence = 0.025 – 0.037, and 2V measured as 64° to 90°, calculated: 76° to 78°. Refractive indices tend to increase from norbergite to clinohumite in the humite group. They also increase with Fe2+ and Ti4+ and with (OH)− substituting for F−. Dispersion: r > v.
Environment
Chondrodite is found largely in metamorphic contact zones between carbonate rocks and acidic or alkaline intrusions where fluorine has been introduced by metasomatic processes. It is formed by the hydration of olivine, , and is stable over a range of temperatures and pressures that include those existing in a portion of the uppermost mantle.
Titanian chondrodite has been found as inclusions in olivine in serpentinite in West Greenland, where it is associated with clinohumite, olivine, magnesite, magnetite and Ni-Co-Pb sulfides in a matrix of antigorite.
See also
Clinohumite
Alleghanyite
Humite
Classification of minerals
List of minerals
References
Magnesium minerals
Iron minerals
Humite group
Monoclinic minerals
Minerals in space group 14
Luminescent minerals | Chondrodite | [
"Chemistry"
] | 884 | [
"Luminescence",
"Luminescent minerals"
] |
2,959,989 | https://en.wikipedia.org/wiki/Phosgenite | Phosgenite is a rare mineral consisting of lead carbonate chloride, (PbCl)2CO3. The tetragonal crystals are prismatic or tabular in habit: they are usually colorless and transparent, and have a brilliant adamantine lustre. Sometimes the crystals have a curious helical twist about the tetrad or principal axis. The hardness is 3 and the specific gravity 6.3. The mineral is rather sectile, and consequently was earlier known as corneous lead, (German Hornblei).
Name and occurrence
The name phosgenite was given by August Breithaupt in 1820, after phosgene, carbon oxychloride, because the mineral contains the elements carbon, oxygen, and chlorine.
It was found associated with anglesite and matlockite in cavities within altered galena in a lead mine at Cromford, near Matlock: hence its common name cromfordite. Crystals are also found in galena at Monteponi near Iglesias in Sardinia, and near Dundas in Tasmania. It has also been reported from Laurium, Greece; Tarnowitz, Poland; the Altai district, Siberia; the Touissit mine, near Oujda, Morocco; Sidi Amor ben Salem, Tunisia; Tsumeb, Namibia; Broken Hill, New South Wales; and Boleo, near Santa Rosalía, Baja California Sur. In the US it has been reported from the Terrible mine, Custer County, Colorado; the Stevenson-Bennett mine, Organ Mountains, Doña Ana County, New Mexico; and the Mammoth mine, Tiger, Pinal County, Arizona.
Crystals of phosgenite, and also of the corresponding bromine compound PbBr2CO3, have been prepared artificially.
See also
Barstowite, another lead chloride carbonate
References
Carbonate minerals
Halide minerals
Lead minerals
Luminescent minerals
Minerals in space group 127
Tetragonal minerals | Phosgenite | [
"Chemistry"
] | 401 | [
"Luminescence",
"Luminescent minerals"
] |
2,960,046 | https://en.wikipedia.org/wiki/Bowtell | Bowtell is derived from the medieval term bottle; in architecture it refers to a round or corniced molding below the abacus in a Tuscan or Roman Doric capital; the word is a variant of boltel, which is probably the diminutive of bolt, the shaft of an arrow or javelin. A roving bowtell is one which passes up the side of a bench end and round a finial, the term roving being applied to that which follows the line of a curve.
Notes
Woodworking
Columns and entablature | Bowtell | [
"Technology"
] | 112 | [
"Structural system",
"Columns and entablature"
] |
2,960,297 | https://en.wikipedia.org/wiki/SIDD | In bioinformatics, SIDD is short for Stress-Induced (DNA) Duplex Destabilization. It is the melting of the DNA which is not induced by a promoter, but purely by the superhelical (also called topological) nature of the DNA. It is based on a statistical mechanics treatment of DNA made by Craig J. Benham and Richard M. Fye. This stress-induced unwinding was shown to coincide with DNA promoter regions of bacterial plasmids and may direct the global response of cells to changes in their external environments by affecting which genes are transcribed.
The computational model itself calculates the probability profile of a given base-pair sequence of DNA to denature, as well as the energy profile of sequence. It is through this energy profile that the technique derives its name: base pairs at lower energies are less stable (destabilized) than those of higher energies and more likely to denature. Stress related to the linking number (specifically its twist component) of the DNA causes the destabilization of the double helix (duplex); hence, Stress-Induced Duplex Destabilization.
Applet
Craig Benham has also developed an online applet that calculates the SIDD profile of input DNA sequences. It also shows the probability profile for the given base pair sequence to denature, as well as counting the number and location of denaturation runs.
As the full SIDD computational method takes up a large amount of machine processing time (due to its complex nature), an accelerated algorithm proposed by Benham, et al., in their 1999 paper is implemented in the WebSIDD algorithm. This accelerated algorithm truncates the partition function by ignoring contributions of certain conformational states.
References
External links
Stress (biology) | SIDD | [
"Chemistry"
] | 369 | [
"Chemical reaction stubs"
] |
2,960,512 | https://en.wikipedia.org/wiki/Tinning | Tinning is the process of thinly coating sheets of wrought iron or steel with tin, and the resulting product is known as tinplate. The term is also widely used for the different process of coating a metal with solder before soldering.
It is most often used to prevent rust, but is also commonly applied to the ends of stranded wire used as electrical conductors to prevent oxidation (which increases electrical resistance), and to keep them from fraying or unraveling when used in various wire connectors like twist-ons, binding posts, or terminal blocks, where stray strands can cause a short circuit.
While once more widely used, the primary use of tinplate now is the manufacture of tin cans. Formerly, tinplate was used for cheap pots, pans, and other holloware. This kind of holloware was also known as tinware and the people who made it were tinplate workers.
The untinned sheets employed in the manufacture are known as black plates. They are now made of steel, either Bessemer steel or open-hearth. Formerly iron was used, and was of two grades, coke iron and charcoal iron; the latter, being the better, received a heavier coating of tin, and this circumstance is the origin of the terms coke plates and charcoal plates by which the quality of tinplate is still designated, although iron is no longer used. Tinplate was consumed in enormous quantities for the manufacture of the tin cans in which preserved meat, fish, fruit, biscuits, cigarettes, and numerous other products are packed, and also for the household utensils of various kinds made by the tinsmith.
History
The practice of tinning ironware to protect it against rust is an ancient one. According to Pliny the Elder tinning was invented by the Gallic Bituriges tribe (based near modern Bourges), who boiled copper objects in a tin solution in order to make them look as if they were made from silver. The first detailed account of the process appears in Zosimus of Panopolis, Book 6.62, part of a work on alchemy written in Roman Egypt around 300 AD. Aside from an attestation in 14th century England, the process is not attested again in Europe until the description in Lazarus Ercker's Das Kleine Probierbuch (1556)
The manufacture of tinplate was long a monopoly of Bohemia, but in about the year 1620 the industry spread to Saxony. Tinplate was apparently produced in the 1620s at a mill of (or under the patronage of) the Earl of Southampton, but it is not clear how long this continued.
Andrew Yarranton, an English engineer and agriculturist, and Ambrose Crowley (a Stourbridge blacksmith and father of the more famous Sir Ambrose Crowley III) were commissioned to go to Saxony and if possible discover the methods employed. They visited Dresden in 1667 and found out how it was made. In doing so, they were sponsored by various local ironmasters and people connected with the project to make the River Stour navigable. In Saxony, the plates were forged, but when they conducted experiments on their return to England, they tried rolling the iron. This led to two of the sponsors, the ironmasters Philip Foley and Joshua Newborough, erecting a new mill, Wolverley Lower Mill (or forge), in 1670. This contained three shops: one being a slitting mill, which would serve as a rolling mill, the others being forges. In 1678 one of these was making frying pans and the other drawing out blooms made in finery forges elsewhere. It is likely that the intention was to roll the plates and then finish them under a hammer, but the plan was frustrated by one William Chamberlaine renewing a patent granted to him and Dud Dudley in 1662. Yarranton described the patent as "trumped up".
The slitter at Wolverley was Thomas Cooke. Another Thomas Cooke, perhaps his son, moved to Pontypool and worked there for John Hanbury (1664–1734). According to Edward Lhuyd, by 1697, John Hanbury had a rolling mill at Pontypool for making "Pontypoole Plates" machine. This has been claimed as a tinplate works, but it was almost certainly only producing (untinned) blackplate. However, this method of rolling iron plates by means of cylinders, enabled more uniform black plates to be produced than was possible with the old plan of hammering, and in consequence the English tinplate became recognised as superior to the German.
Tinplate first begins to appear in the Gloucester Port Books (which record trade passing through Gloucester, mostly from ports in the Bristol Channel) in 1725. The tinplate was shipped from Newport, Monmouthshire. This immediately follows the first appearance (in French) of Réaumur's Principes de l'art de fer-blanc, and prior to a report of it being published in England.
Further mills followed a few years later, initially in many ironmaking regions in England and Wales, but later mainly in south Wales. In 1805, 80,000 boxes were made and 50,000 exported. The industry continued to spread steadily in England and especially Wales, and after 1834 its expansion was rapid, Great Britain becoming the chief source of the world's supply. In that year her total production was 180,000 boxes of 108 lb each (around 50 kg, in America a box is 100 lb), in 1848 it was 420,000 boxes, in 1860 it reached 1,700,000 boxes. But subsequently the advance was rapid, and the production reached about 2,236,000 lb in 1891. One of the greatest markets was the United States of America, but that market was cut off in 1891, when the McKinley tariff was enacted there. This caused a great retrenchment in the British industry and the emigration to America of many of those who could no longer be employed in the surviving tinplate works.
In 1891, the United States made 11,000 tons of tinplate and imported 325,100 tons, but in 1899, it made 360,900 tons, importing only 63,500 tons (mostly for re-export). British exports were further hindered by the Dingley tariff, which removed the advantage of Welsh plate on America's Pacific coast, had by 1900 increased to more than 849,000,000 lb, of which over 141,000,000 lb were terne-plates. The total imports in that year were only 135,264,881 lb. In later years, again, there was a decline in the American production, and in 1907 only 20% of the American tinplate mills were at work, while the British production reached 14 million boxes.
Despite this blow, the industry continued, but on a smaller scale. Nevertheless, there were still 518 mills in operation in 1937, including 224 belonging to Richard Thomas & Co. However the traditional 'pack mill' had been overtaken by the improved 'strip mill', of which the first in Great Britain was built by Richard Thomas & Co. in the late 1930s. Strip mills rendered the old pack mills obsolete and the last of them closed in about the 1960s.
Plate production methods
The pack mill process
The pack mill process begins with a tin bar, which is a drawn flat bar that was usually purchased from an ironworks or steel works. The tin bar could be wrought iron or mild steel. The cross-section of the bar needed to be accurate in size as this dictates the length and thickness of the final plates. The bar was cut to the correct length to make the desired size plate. For instance, if a plate is desired the tin bar is cut to a length and width that is divisible by 14 and 20. The bar is then rolled and doubled over, with the number of times being doubled over dependent on how large the tin bar is and what the final thickness is. If the starting tin bar is then it must be at least finished on the fours, or doubled over twice, and if a thin gauge is required then it may be finished on the eights, or doubled over three times. The tin bar is then heated to a dull red heat and passed five or six times through the roughing rolls. Between each pass the plate is passed over (or round) the rolls, and the gap between the rolls is narrowed by means of a screw. The plate is then reheated and run through the finishing rolls.
If the plate is not finished on singles, or without doubling the plate over, it is doubled over in a squeezer. The squeezer was like a table where one half of the surface folds over on top of the other and a press flattens the doubled over plate so the rolled end will fit in the rollers. It is then reheated for another set of rolling. This is repeated until the desired geometry is reached. Note that if the plate needs to be doubled over more than once the rolled end is sheared off. The pack is then allowed to cool. When cool, the pack is sheared slightly undersized from the final dimensions and the plates separated by openers.
At this point, the plates are covered in scale and must be pickled. This involves dipping the plates in sulfuric acid for five minutes. The pickling turns the scales into a greenish-black slime which is removed via annealing. The plates are annealed for approximately 10 hours and then allowed to slowly cool. At this point the plates are known as pickled and annealed black plates. These plates were commonly sold for stamping and enameling purposes.
After this, the plates are rough and not straight, so they are cold rolled several times. The rolling lengthens the plates to their final dimension. They are then annealed again to remove any strain hardening. These plates are called black plate pickled, cold rolled, and close annealed (black plate p. cr. and ca.). To attain perfect cleanliness the plates are pickled again in a weak sulfuric acid. Finally they are rinsed and stored in water until ready to be tinned.
The tinning set consists of at least one pot of molten tin, with a zinc chloride flux on top, and a grease pot. The flux dries the plate and prepares it for the tin to adhere. If a second tin pot is used, called the wash pot, it contains tin at a lower temperature. This is followed by the grease pot, which contains oil and a tinning machine. The tinning machine has two small rollers that are spring-loaded together so that when the tinned plate is inserted the rolls squeeze off any excess tin. The springs on the tinning machine can be set to different forces to give different thicknesses of tin. Finally, the oil is cleaned off with fine bran and dusted clean.
What is described here is the process as employed during the 20th century. The process grew somewhat in complexity over time, as it was found that the inclusion of additional procedures improved quality. The practice of hot rolling and then cold rolling evidently goes back to the early days, as the Knight family's tinplate works had (from its foundation in about 1740) two rolling mills, one at Bringewood (west of Ludlow) which made blackplate, and the other the tin mill at Mitton (now part of Stourport, evidently for the later stages.
The strip mill
Early hot rolling strip mills did not produce strip suitable for tinning, but in 1929 cold rolling began to be used to reduce the gauge further, which made tinning achievable. The plate was then tinned using the process outlined above.
Tinning processes
There are two processes for the tinning of the black plates: hot-dipping and electroplating.
Hot-dipping
Hot tin-dipping is the process of immersing a part into a bath of pure molten tin at a temperature greater than 450 °F or 232 °C.
Tinplate made via hot-dipped tin plating is made by cold rolling steel or iron, pickling to remove any scale, annealing to remove any strain hardening, and then coating it with a thin layer of tin. Originally this was done by producing individual or small packs of plates, which became known as the pack mill process. In the late 1920s strip mills began to replace pack mills, because they could produce the raw plates in larger quantities and more economically.
Electroplating
In electroplating, the item to be coated is placed into a container containing a solution of one or more tin salts. The item is connected to an electrical circuit, forming the cathode (negative) of the circuit while an electrode typically of the same metal to be plated forms the anode (positive). When an electric current is passed through the circuit, metal ions in the solution are attracted to the item. To produce a smooth, shiny surface, the electroplated sheet is then briefly heated above the melting point of tin. Most of the tin-plated steel made today is then further electroplated with a very thin layer of chromium to prevent dulling of the surface from oxidation of the tin.
Alternatives
Terne-plate is a similar product to tinplate, but the bath is not of tin, but of tin and lead mixed, the latter metal constituting from 7.59% of the whole. The name derives from "terne", meaning dull or tarnish. Terne-plates began to be produced in England about the middle of the 19th century, and became widely employed in the United States for roofing purposes. Other applications included fuel tanks and gas meters. The last Terne-plate mill in Brockmoor, West Midlands in the UK was closed in 2006.
For many purposes, tinplate has been replaced by galvanised (zinc-coated) vessels - though not for cooking, as zinc can be toxic. A Zinc protects iron electrolytically, that is, the zinc will oxidise and turn to a white powder to preserve the iron, whereas tin will only protect the iron if the tin-surface remains unbroken, as it electrolytically cannibalises unprotected iron to preserve itself.
See also
Blackplate
Kalai (process), a form of tinning practiced in India
Plating for other processes for plating metals
Sherardizing
Tinsmith
Tinware
Black oxide
References
Bibliography
Further reading
F. W. Gibbs, 'The rise of the tinplate industry' Annals of Science 6 (1950), 390ff; 7(1) (1951), 25ff; 43ff; 113ff.
P. Jenkins, 'Twenty by Fourteen': a history of the south Wales tinplate industry 1700-1961 (Gomer, Llandysul, Dyfed 1995).
D.A. Irwin, 'Did late nineteenth century U.S. tariffs promote infant industries? Evidence from the tinplate industry' (NBER working paper 6835 1998)
Coatings
Industrial processes
Metal plating
Metallurgical processes
Steelmaking
Thin film deposition
Tin | Tinning | [
"Chemistry",
"Materials_science",
"Mathematics"
] | 3,078 | [
"Thin film deposition",
"Metallurgical processes",
"Metallurgy",
"Coatings",
"Steelmaking",
"Thin films",
"Planes (geometry)",
"Solid state engineering",
"Metal plating"
] |
2,960,796 | https://en.wikipedia.org/wiki/Molecular%20chaos | In the kinetic theory of gases in physics, the molecular chaos hypothesis (also called Stosszahlansatz in the writings of Paul and Tatiana Ehrenfest) is the assumption that the velocities of colliding particles are uncorrelated, and independent of position. This means the probability that a pair of particles with given velocities will collide can be calculated by considering each particle separately and ignoring any correlation between the probability for finding one particle with velocity and probability for finding another velocity in a small region . James Clerk Maxwell introduced this approximation in 1867 although its origins can be traced back to his first work on the kinetic theory in 1860.
The assumption of molecular chaos is the key ingredient that allows proceeding from the BBGKY hierarchy to Boltzmann's equation, by reducing the 2-particle distribution function showing up in the collision term to a product of 1-particle distributions. This in turn leads to Boltzmann's H-theorem of 1872, which attempted to use kinetic theory to show that the entropy of a gas prepared in a state of less than complete disorder must inevitably increase, as the gas molecules are allowed to collide. This drew the objection from Loschmidt that it should not be possible to deduce an irreversible process from time-symmetric dynamics and a time-symmetric formalism: something must be wrong (Loschmidt's paradox). The resolution (1895) of this paradox is that the velocities of two particles after a collision are no longer truly uncorrelated. By asserting that it was acceptable to ignore these correlations in the population at times after the initial time, Boltzmann had introduced an element of time asymmetry through the formalism of his calculation.
Though the Stosszahlansatz is usually understood as a physically grounded hypothesis, it was recently highlighted that it could also be interpreted as a heuristic hypothesis. This interpretation allows using the principle of maximum entropy in order to generalize the ansatz to higher-order distribution functions.
See also
Free molecular flow
References
Philosophy of thermal and statistical physics
Statistical mechanics | Molecular chaos | [
"Physics",
"Chemistry"
] | 434 | [
"Statistical mechanics stubs",
"Statistical mechanics",
"Philosophy of thermal and statistical physics",
"Thermodynamics"
] |
2,961,091 | https://en.wikipedia.org/wiki/Fluent%20calculus | The fluent calculus is a formalism for expressing dynamical domains in first-order logic. It is a variant of the situation calculus; the main difference is that situations are considered representations of states. A binary function symbol is used to concatenate the terms that represent facts that hold in a situation. For example, that the box is on the table in the situation is represented by the formula . The frame problem is solved by asserting that the situation after the execution of an action is identical to the one before but for the conditions changed by the action. For example, the action of moving the box from the table to the floor is formalized as:
This formula states that the state after the move is added the term and removed the term . Axioms specifying that is commutative and non-idempotent are necessary for such axioms to work.
See also
Fluent (artificial intelligence)
Frame problem
Situation calculus
Event calculus
References
M. Thielscher (1998). Introduction to the fluent calculus. Electronic Transactions on Artificial Intelligence, 2(3–4):179–192.
M. Thielscher (2005). Reasoning Robots - The Art and Science of Programming Robotic Agents. Volume 33 of Applied Logic Series. Springer, Dordrecht.
Logical calculi | Fluent calculus | [
"Mathematics"
] | 261 | [
"Mathematical logic",
"Logical calculi"
] |
2,961,833 | https://en.wikipedia.org/wiki/Spatial%20reference%20system | A spatial reference system (SRS) or coordinate reference system (CRS) is a framework used to precisely measure locations on the surface of Earth as coordinates. It is thus the application of the abstract mathematics of coordinate systems and analytic geometry to geographic space. A particular SRS specification (for example, "Universal Transverse Mercator WGS 84 Zone 16N") comprises a choice of Earth ellipsoid, horizontal datum, map projection (except in the geographic coordinate system), origin point, and unit of measure. Thousands of coordinate systems have been specified for use around the world or in specific regions and for various purposes, necessitating transformations between different SRS.
Although they date to the Hellenic Period, spatial reference systems are now a crucial basis for the sciences and technologies of Geoinformatics, including cartography, geographic information systems, surveying, remote sensing, and civil engineering. This has led to their standardization in international specifications such as the EPSG codes and ISO 19111:2019 Geographic information—Spatial referencing by coordinates, prepared by ISO/TC 211, also published by the Open Geospatial Consortium as Abstract Specification, Topic 2: Spatial referencing by coordinate.
Types of systems
The thousands of spatial reference systems used today are based on a few general strategies, which have been defined in the EPSG, ISO, and OGC standards:
Geographic coordinate system (or geodetic)
A spherical coordinate system measuring locations directly on the Earth (modeled as a sphere or ellipsoid) using latitude (degrees north or south of the equator) and longitude (degrees west or east of a prime meridian).
Geocentric coordinate system (or Earth-centered Earth-fixed)
A three-dimensional cartesian coordinate system that models the Earth as a three-dimensional object, measuring locations from a center point, usually the center of mass of the Earth, along x, y, and z axes aligned with the equator and the prime meridian. This system is commonly used to track the orbits of satellites, because they are based on the center of mass. Thus, this is the internal coordinate system used by Satellite navigation systems such as GPS to compute locations using multilateration.
Projected coordinate system (or planar, grid)
A standardized cartesian coordinate system that models the Earth (or more commonly, a large region thereof) as a plane, measuring locations from an arbitrary origin point along x and y axes more or less aligned with the cardinal directions. Each of these systems is based on a particular Map projection to create a planar surface from the curved Earth surface. These are generally defined and used strategically to minimize the distortions inherent to projections. Common examples include the Universal transverse mercator (UTM) and national systems such as the British National Grid, and State Plane Coordinate System (SPCS).
Engineering coordinate system (or local, custom)
A cartesian coordinate system (2-D or 3-D) that is created bespoke for a small area, often a single engineering project, over which the curvature of the Earth can be safely approximated as flat without significant distortion. Locations are typically measured directly from an arbitrary origin point using surveying techniques. These may or may not be aligned with a standard projected coordinate system. Local tangent plane coordinates are a type of local coordinate system used in aviation and marine vehicles.
Vertical reference frame a standard reference system for measuring elevation using vertical datums, based on levelling, a geoid model, or a chart datum (considering tides).
These standards acknowledge that standard reference systems also exist for time (e.g. ISO 8601). These may be combined with a spatial reference system to form a compound coordinate system for representing three-dimensional and/or spatio-temporal locations. There are also internal systems for measuring location within the context of an object, such as the rows and columns of pixels in a raster image, Linear referencing measurements along linear features (e.g., highway mileposts), and systems for specifying location within moving objects such as ships. The latter two are often classified as subcategories of engineering coordinate systems.
Components
The goal of any spatial reference system is to create a common reference frame in which locations can be measured precisely and consistently as coordinates, which can then be shared unambiguously, so that any recipient can identify the same location that was originally intended by the originator. To accomplish this, any coordinate reference system definition needs to be composed of several specifications:
A coordinate system, an abstract framework for measuring locations. Like any mathematical coordinate system, its definition consists of a measurable space (whether a plane, a three-dimension void, or the surface of an object such as the Earth), an origin point, a set of axis vectors emanating from the origin, and a unit of measure.
A geodetic datum (horizontal, vertical, or three-dimensional) which binds the abstract coordinate system to the real space of the Earth. A horizontal datum can be defined as a precise reference framework for measuring geographic coordinates (latitude and longitude). Examples include the World Geodetic System and the 1927 and 1983 North American Datum. A datum generally consists of an estimate of the shape of the Earth (usually an ellipsoid), and one or more anchor points or control points, established locations (often marked by physical monuments) for which the measurement is documented.
A definition for a projected CRS must also include a choice of map projection to convert the spherical coordinates specified by the datum into cartesian coordinates on a planar surface.
Thus, a CRS definition will typically consist of a "stack" of dependent specifications, as exemplified in the following table:
Examples by continent
Examples of systems around the world are:
Asia
Chinese Global Navigation Grid Code, China
Israeli Cassini Soldner, Israel
Israeli Transverse Mercator, Israel
Jordan Transverse Mercator, Jordan
Europe
British national grid reference system, Britain
Lambert-93 (fr), the official projection in Metropolitan France
Hellenic Geodetic Reference System 1987, Greece
Irish grid reference system, Ireland
Irish Transverse Mercator, Ireland
SWEREF 99 (sv), Sweden
North America
United States National Grid, US
Worldwide
Universal Transverse Mercator coordinate system
Lambert conformal conic projection
International mapcode system
Military Grid Reference System
Identifiers
A Spatial Reference System Identifier (SRID) is a unique value used to unambiguously identify projected, unprojected, and local spatial coordinate system definitions. These coordinate systems form the heart of all GIS applications.
Virtually all major spatial vendors have created their own SRID implementation or refer to those of an authority, such as the EPSG Geodetic Parameter Dataset.
SRIDs are the primary key for the Open Geospatial Consortium (OGC) spatial_ref_sys metadata table for the Simple Features for SQL Specification, Versions 1.1 and 1.2, which is defined as follows:
CREATE TABLE SPATIAL_REF_SYS
(
SRID INTEGER NOT NULL PRIMARY KEY,
AUTH_NAME CHARACTER VARYING(256),
AUTH_SRID INTEGER,
SRTEXT CHARACTER VARYING(2048)
)
In spatially enabled databases (such as IBM Db2, IBM Informix, Ingres, Microsoft SQL Server, MonetDB, MySQL, Oracle RDBMS, Teradata, PostGIS, SQL Anywhere and Vertica), SRIDs are used to uniquely identify the coordinate systems used to define columns of spatial data or individual spatial objects in a spatial column (depending on the spatial implementation). SRIDs are typically associated with a well-known text (WKT) string definition of the coordinate system (SRTEXT, above).
Here are two common coordinate systems with their EPSG SRID value followed by their WKT:
UTM, Zone 17N, NAD27 — SRID 2029:
PROJCS["NAD27(76) / UTM zone 17N",
GEOGCS["NAD27(76)",
DATUM["North_American_Datum_1927_1976",
SPHEROID["Clarke 1866",6378206.4,294.9786982138982,
AUTHORITY["EPSG","7008"]],
AUTHORITY["EPSG","6608"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4608"]],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",-81],
PARAMETER["scale_factor",0.9996],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
AUTHORITY["EPSG","2029"],
AXIS["Easting",EAST],
AXIS["Northing",NORTH]]
WGS84 — SRID 4326
GEOGCS["WGS 84",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4326"]]
SRID values associated with spatial data can be used to constrain spatial operations — for instance, spatial operations cannot be performed between spatial objects with differing SRIDs in some systems, or trigger coordinate system transformations between spatial objects in others.
See also
Engineering datum
Geodesy
Geodetic datum
Georeferencing
Geographic coordinate systems
Geographic information system (GIS).
Grid reference
Linear referencing
List of National Coordinate Reference Systems
Terms of orientation
References
External links
spatialreference.org – A website with more than 13000 spatial reference systems, in a variety of formats.
OpenGIS Specifications (Standards)
OpenGIS Simple Features Specification for CORBA (99-054)
OpenGIS Simple Features Specification for OLE/COM (99-050)
OpenGIS Simple Features Specification for SQL (99-054, 05-134, 06-104r3)
OGR — library implementing relevant OGC standards
EPSG.org - Official EPSG Geodetic Parameter Dataset webpage. Search engine for EPSG defined reference systems.
EPSG.io/ - Full text search indexing over 6000 coordinate systems
Galdos Systems INdicio CRS Registry
Geographic coordinate systems
Geographic information systems
Geodesy
ISO/TC 211
Open Geospatial Consortium
GIS file formats | Spatial reference system | [
"Mathematics",
"Technology"
] | 2,303 | [
"Applied mathematics",
"Geographic information systems",
"Geographic coordinate systems",
"Information systems",
"Coordinate systems",
"Geodesy"
] |
2,961,998 | https://en.wikipedia.org/wiki/ESTAR%20project | The eSTAR project was a multi-agent system that aimed to implement a heterogeneous network of robotic telescopes for automated observing, and ground-based follow-up to transient events. The project is a joint collaboration between the Astrophysics Group of the University of Exeter and the Astrophysics Research Institute at Liverpool John Moores University. The project was led by Alasdair Allan and Tim Naylor at the University of Exeter, and Iain Steele at Liverpool John Moores University. The eSTAR Project was affiliated with the RoboNet Consortium, and the global Heterogeneous Telescope Networks Consortium.
Begun in 2001, the project was part of the virtual observatory. By 2006 the project was running autonomous software agent for observations of variable stars implementing the optimal sampling techniques of Saunders et al. (2006), and the prototype was successfully tested on the RoboNet network of telescopes which includes: the Liverpool Telescope, the Faulkes Telescope North and the Faulkes Telescope South.
By 2007 the eSTAR Project was "live" supporting two real-time observing projects.
The first was automated follow-up observations of gamma-ray bursts performed using the 3.8m United Kingdom Infrared Telescope (UKIRT) operated by Joint Astronomy Centre in Hawaii (JACH). The first ground based observations of GRB 090423 were triggered via the eSTAR Project, with initial observations by the Swift Gamma-Ray Burst Mission automatically followed by UKIRT just a few minutes after the initial observation by the SWIFT satellite. The observations autonomously triggered by the eSTAR software were reported in Tanvir et al. This gamma-ray burst was, at the time of discovery, the most distant object then known in the Universe.
The second project was the search for extra-solar planets by placing observations on the RoboNet system of telescopes on behalf of the PLANET collaboration. The technique of gravitational microlensing is used to monitor large numbers of stars in the galactic bulge looking for the tell-tale signature of cool planets orbiting those stars.
The project also operated the heaviest used of the initial generation of Virtual Observatory VOEvent brokers, exposing its real-time alert system to other collaborators, like the TALONS Project.
In 2009 the project lost funding and was shuttered.
References
Observational astronomy
University of Exeter
Liverpool John Moores University
Robotic telescopes
Agent-based software
2006 robots
Robots of the United Kingdom | ESTAR project | [
"Astronomy"
] | 483 | [
"Observational astronomy",
"Astronomical sub-disciplines"
] |
2,962,342 | https://en.wikipedia.org/wiki/Security%20operations%20center | A security operations center (SOC) is responsible for protecting an organization against cyber threats. SOC analysts perform round-the-clock monitoring of an organization’s network and investigate any potential security incidents. If a cyberattack is detected, the SOC analysts are responsible for taking any steps necessary to remediate it. It comprises the three building blocks for managing and enhancing an organization's security posture: people, processes, and technology. Thereby, governance and compliance provide a framework, tying together these building blocks. A SOC within a building or facility is a central location from which staff supervises the site using data processing technology. Typically, a SOC is equipped for access monitoring and control of lighting, alarms, and vehicle barriers.
SOC can be either internal or external. In latter case the organization outsources the security services, such monitoring, detection and analysis, from a Managed Security Service Provider (MSSP). This is typical to small organizations which don't have the resources to hire, train, and technically equip cybersecurity analysts.
IT
An information security operations center (ISOC) is a dedicated site where enterprise information systems (web sites, applications, databases, data centers and servers, networks, desktops and other endpoints) are monitored, assessed, and defended.
The United States government
The Transportation Security Administration in the United States has implemented security operations centers for most airports that have federalized security. The primary function of TSA security operations centers is to act as a communication hub for security personnel, law enforcement, airport personnel and various other agencies involved in the daily operations of airports. SOCs are staffed 24-hours a day by SOC watch officers. Security operations center watch officers are trained in all aspects of airport and aviation security and are often required to work abnormal shifts. SOC watch officers also ensure that TSA personnel follow proper protocol in dealing with airport security operations. The SOC is usually the first to be notified of incidents at airports such as the discovery of prohibited items/contraband, weapons, explosives, hazardous materials as well as incidents regarding flight delays, unruly passengers, injuries, damaged equipment and various other types of potential security threats. The SOC in turn relays all information pertaining to these incidents to TSA federal security directors, law enforcement and TSA headquarters.
See also
National SIGINT Operations Centre
References
Security
Surveillance
Security engineering | Security operations center | [
"Engineering"
] | 477 | [
"Systems engineering",
"Security engineering"
] |
2,962,357 | https://en.wikipedia.org/wiki/Relativistic%20electromagnetism | Relativistic electromagnetism is a physical phenomenon explained in electromagnetic field theory due to Coulomb's law and Lorentz transformations.
Electromechanics
After Maxwell proposed the differential equation model of the electromagnetic field in 1873, the mechanism of action of fields came into question, for instance in the Kelvin's master class held at Johns Hopkins University in 1884 and commemorated a century later.
The requirement that the equations remain consistent when viewed from various moving observers led to special relativity, a geometric theory of 4-space where intermediation is by light and radiation. The spacetime geometry provided a context for technical description of electric technology, especially generators, motors, and lighting at first. The Coulomb force was generalized to the Lorentz force. For example, with this model transmission lines and power grids were developed and radio frequency communication explored.
An effort to mount a full-fledged electromechanics on a relativistic basis is seen in the work of Leigh Page, from the project outline in 1912 to his textbook Electrodynamics (1940) The interplay (according to the differential equations) of electric and magnetic field as viewed over moving observers is examined. What is charge density in electrostatics becomes proper charge density and generates a magnetic field for a moving observer.
A revival of interest in this method for education and training of electrical and electronics engineers broke out in the 1960s after Richard Feynman's textbook.
Rosser's book Classical Electromagnetism via Relativity was popular, as was Anthony French's treatment in his textbook which illustrated diagrammatically the proper charge density. One author proclaimed, "Maxwell — Out of Newton, Coulomb, and Einstein".
The use of retarded potentials to describe electromagnetic fields from source-charges is an expression of relativistic electromagnetism.
Principle
The question of how an electric field in one inertial frame of reference looks in different reference frames moving with respect to the first is crucial to understanding fields created by moving sources. In the special case, the sources that create the field are at rest with respect to one of the reference frames. Given the electric field in the frame where the sources are at rest, one can ask: what is the electric field in some other frame? Knowing the electric field at some point (in space and time) in the rest frame of the sources, and knowing the relative velocity of the two frames provided all the information needed to calculate the electric field at the same point in the other frame. In other words, the electric field in the other frame does not depend on the particular distribution of the source charges, only on the local value of the electric field in the first frame at that point. Thus, the electric field is a complete representation of the influence of the far-away charges.
Alternatively, introductory treatments of magnetism introduce the Biot–Savart law, which describes the magnetic field associated with an electric current. An observer at rest with respect to a system of static, free charges will see no magnetic field. However, a moving observer looking at the same set of charges does perceive a current, and thus a magnetic field. That is, the magnetic field is simply the electric field, as seen in a moving coordinate system.
Redundancy
The title of this article is redundant since all mathematical theories of electromagnetism are relativistic.
Indeed, as Einstein wrote, "The special theory of relativity ... was simply a systematic development of the electrodynamics of Clerk Maxwell and Lorentz".
Combination of spatial and temporal variables in Maxwell's theory required admission of a four-manifold. Finite light speed and other constant motion lines were described with analytic geometry. Orthogonality of electric and magnetic vector fields in space was extended by hyperbolic orthogonality for the temporal factor.
When Ludwik Silberstein published his textbook The Theory of Relativity (1914) he related the new geometry to electromagnetism. Faraday's law of induction was suggestive to Einstein when he wrote in 1905 about the "reciprocal electrodynamic action of a magnet and a conductor".
Nevertheless, the aspiration, reflected in references for this article, is for an analytic geometry of spacetime and charges providing a deductive route to forces and currents in practice. Such a royal route to electromagnetic understanding may be lacking, but a path has been opened with differential geometry: The tangent space at an event in spacetime is a four-dimensional vector space, operable by linear transformations. Symmetries observed by electricians find expression in linear algebra and differential geometry. Using exterior algebra to construct a 2-form F from electric and magnetic fields, and the implied dual 2-form ★F, the equations and (current) express Maxwell's theory with a differential form approach.
See also
Covariant formulation of classical electromagnetism
Special relativity
Liénard–Wiechert potential
Moving magnet and conductor problem
Wheeler–Feynman absorber theory
Paradox of a charge in a gravitational field
Notes and references
Further reading
Electromagnetism
Electromagnetism | Relativistic electromagnetism | [
"Physics"
] | 1,034 | [
"Electromagnetism",
"Physical phenomena",
"Special relativity",
"Fundamental interactions",
"Theory of relativity"
] |
2,962,530 | https://en.wikipedia.org/wiki/Trough%20level | In medicine and pharmacology, a trough level or trough concentration () is the concentration reached by a drug immediately before the next dose is administered, often used in therapeutic drug monitoring. The name comes from the idea that on a graph of concentration versus time, the line forms a U-shaped trough at the lowest region, before a new dose sends it higher again. The usual criterion is concentration in the blood serum, although in some instances local concentration within tissues is relevant. It is pharmacokinetically normal that over time, the drug molecules are being metabolized or cleared by the body, so the concentration of drug that remains available is dropping. In a medicine that is administered periodically, the trough level should be measured just before the administration of the next dose in order to avoid overdosing. A trough level is contrasted with a "peak level" (), which is the highest level of the medicine in the body, and the "average level", which is the mean level over time. It is widely used in clinical trials for newer medicines to investigate therapeutic effectiveness and safety.
is slightly different from , the minimum concentration during the time interval between administration of two doses.
References
Pharmacokinetics | Trough level | [
"Chemistry"
] | 249 | [
"Pharmacology",
"Pharmacology stubs",
"Pharmacokinetics",
"Medicinal chemistry stubs"
] |
2,963,141 | https://en.wikipedia.org/wiki/Creepmeter | A creepmeter is an instrument that monitors the slow surface displacement of an active geologic fault in the Earth. Its function is to record the slow, aseismic creep between earthquakes. The measurement range of a creepmeter is usually limited to 10–30 mm. Approximately 40 creepmeters are in operation in California—most are operated by the United States Geological Survey (USGS), but nine are maintained by the University of Colorado.
References
Structural geology
Measuring instruments
Seismology | Creepmeter | [
"Technology",
"Engineering"
] | 97 | [
"Measuring instruments"
] |
2,963,333 | https://en.wikipedia.org/wiki/Kuromido | Kuromido (Japanese: 黒味銅) is an historically Japanese copper alloy, typically of 99% copper and 1% metallic arsenic, one of the class of irogane metals.
It is used in the production of other alloys, and in decorative fittings, as well as in mokume-gane processes.
See also
Shakudō
Shibuichi
Corinthian bronze and hepatizon (Black bronze)
Electrum
Orichalcum
Panchaloha
Tumbaga
External sources
References
Irogane
Copper alloys
Arsenic | Kuromido | [
"Chemistry"
] | 111 | [
"Copper alloys",
"Alloys",
"Alloy stubs"
] |
2,964,127 | https://en.wikipedia.org/wiki/Blattner%27s%20conjecture | In mathematics, Blattner's conjecture or Blattner's formula is a description of the discrete series representations of a general semisimple group G in terms of their restricted representations to a maximal compact subgroup K (their so-called K-types). It is named after Robert James Blattner, despite not being formulated as a conjecture by him.
Statement
Blattner's formula says that if a discrete series representation with infinitesimal character λ is restricted to a maximal compact subgroup K, then the representation of K with highest weight μ occurs with multiplicity
where
Q is the number of ways a vector can be written as a sum of non-compact positive roots
WK is the Weyl group of K
ρc is half the sum of the compact roots
ρn is half the sum of the non-compact roots
ε is the sign character of WK.
Blattner's formula is what one gets by formally restricting the Harish-Chandra character formula for a discrete series representation to the maximal torus of a maximal compact group. The problem in proving the Blattner formula is that this only gives the character on the regular elements of the maximal torus, and one also needs to control its behavior on the singular elements. For non-discrete irreducible representations the formal restriction of Harish-Chandra's character formula need not give the decomposition under the maximal compact subgroup: for example, for the principal series representations of SL2 the character is identically zero on the non-singular elements of the maximal compact subgroup, but the representation is not zero on this subgroup. In this case the character is a distribution on the maximal compact subgroup with support on the singular elements.
History
Harish-Chandra orally attributed the conjecture to Robert James Blattner as a question Blattner raised, not a conjecture made by Blattner. Blattner did not publish it in any form. It first appeared in print in , where it was first referred to as "Blattner's Conjecture," despite the results of that paper having been obtained without knowledge of Blattner's question and notwithstanding Blattner's not having made such a conjecture. mentioned a special case of it slightly earlier.
showed that Blattner's formula gave an upper bound for the multiplicities of K-representations, proved Blattner's conjecture for groups whose symmetric space is Hermitian, and proved Blattner's conjecture for linear semisimple groups. Blattner's conjecture (formula) was also proved by by infinitesimal methods which were totally new and completely different from those of Hecht and Schmid (1975). Part of the impetus for Enright’s paper (1979) came from several sources: from , , . In Enright (1979) multiplicity formulae are given for the so-called mock-discrete series representations also. used his ideas to obtain results on the construction and classification of irreducible Harish-Chandra modules of any real semisimple Lie algebra.
References
Representation theory of Lie groups
Conjectures | Blattner's conjecture | [
"Mathematics"
] | 627 | [
"Unsolved problems in mathematics",
"Mathematical problems",
"Conjectures"
] |
2,964,194 | https://en.wikipedia.org/wiki/Mutacin%201140 | Mutacin 1140 is a bacteriocin produced by Streptococcus mutans. It has activity against a broad spectrum of Gram-positive bacteria. It is a member of the class of compounds known as lantibiotics.
Mutacin 1140 belongs to the epidermin subset of type Al lantibiotics. Molecules belonging to this family bind to lipid II which is a precursor to bacterial cell wall synthesis.
While the effects mutacin 1140 has against gram-positive bacteria are known, it remains difficult to study due to it demonstrating poor pharmacokinetics. Besides the poor pharmacokinetics, it is easily vulnerable to proteolytic degradation by interfering with the protein's peptide bonds.
References
Lantibiotics
Bacteriocins | Mutacin 1140 | [
"Chemistry",
"Biology"
] | 167 | [
"Biochemistry stubs",
"Biotechnology stubs",
"Biochemistry"
] |
2,964,298 | https://en.wikipedia.org/wiki/Service%20for%20French%20Internet%20Exchange | The Service for French Internet Exchange (SFINX) is a French IXPs (Internet Exchange Points), along with France-IX and PARIX. It's PoPs are based at Interxion "Paris 1" in Aubervilliers and Telehouse "Paris 2" in the 11th arrondissement of Paris.
It is operated by RENATER, the French National Research and Education Network (NREN).
See also
List of Internet exchange points
List of Internet exchange points by size
Internet exchange
Peering
References
External links
SFINX Web Page
Internet exchange points in France
Internet in France | Service for French Internet Exchange | [
"Technology"
] | 119 | [
"Computing stubs",
"Computer network stubs"
] |
15,888,102 | https://en.wikipedia.org/wiki/Indispensable%20Reefs | The Indispensable Reefs are a chain of three large coral atolls in the Coral Sea. They are located about south of Rennell Island. The chain stretches over a length of and its average width is .
Administratively the Indispensable Reef belongs to the Rennell and Bellona Province of Solomon Islands. They are locally called "Goto'akau".
The three atolls are steep-to and each encloses a large deep lagoon. They are separated by deep passages wide. The atolls of the Indispensable Reef are aligned in a NW-SE direction:
North Reef is long, and up to wide. The rim of the atoll has two narrow openings in the north and northwest. The reef has a total area of , including lagoon and reef flat. There are no islets.
Middle Reef is long. Little Nottingham Islet is a small islet located near the centre of the reef. Besides its main lagoon, Middle Reef has a separate smaller northern lagoon. The total area is about .
South Reef is long and up to wide. It encloses a lagoon deep. The total area exceeds .
History
The ship Neptune struck Indispensable Reef on 3 August 1868, and was lost. The crew was rescued by the SS Boomerang.
During the Battle of the Coral Sea on 7 May 1942, two Japanese carrier attack planes B5N2 (EI-306 and probably EI-302) flying reconnaissance mission from the carrier Shokaku ditched on Indispensable Reef due to lack of fuel.
In 1983, the Solomon Islands Government apprehended a vessel from Taiwan that had been poaching the giant clam stocks around Indispensable Reef. Corals and endangered fish species are also being plundered for the aquarium trade.
See also
Desert island
List of islands
References
External links
https://web.archive.org/web/20080120072247/http://solomonislands.com.sb/indispensablereefs.html
Corals:
Sunken ships:
Ecological concern:
Uninhabited islands of the Solomon Islands
Reefs of the Pacific Ocean
Atolls of the Solomon Islands
Landforms of the Coral Sea
Coral reefs
Rennell and Bellona Islands | Indispensable Reefs | [
"Biology"
] | 456 | [
"Biogeomorphology",
"Coral reefs"
] |
15,889,114 | https://en.wikipedia.org/wiki/Formerly%20Utilized%20Sites%20Remedial%20Action%20Program | The Formerly Utilized Sites Remedial Action Program (FUSRAP) is a United States Army Corps of Engineers (USACE) project to manage and cleanup environmental contamination that resulted from early United States Atomic Energy Commission activities. Cleanup activities were initially performed under the supervision of the United States Department of Energy (DOE), until 1997 when the United States Congress passed authority for cleanup activities to the USACE.
The primary source of contamination at the locations stems from the processing of uranium ores and the disposal of the byproducts. The major sources of site contamination are uranium, thorium, and radium. In addition to the radiological contaminants there are semi-volatile organic compounds, volatile organic compounds, and heavy metals comingled at the sites.
Table of FUSRAP Sites
Data from multiple sources
References
External links
Saint Louis FUSRAP Site
Buffalo District FUSRAP Webpage
North Atlantic/NY fusrap
Radioactive waste
United States Army Corps of Engineers
Nuclear weapons infrastructure of the United States | Formerly Utilized Sites Remedial Action Program | [
"Chemistry",
"Technology",
"Engineering"
] | 203 | [
"United States Army Corps of Engineers",
"Engineering units and formations",
"Environmental impact of nuclear power",
"Hazardous waste",
"Radioactivity",
"Radioactive waste"
] |
15,889,648 | https://en.wikipedia.org/wiki/Proof%20by%20intimidation | Proof by intimidation (or argumentum verbosum) is a jocular phrase used mainly in mathematics to refer to a specific form of hand-waving whereby one attempts to advance an argument by giving an argument loaded with jargon and obscure results or by marking it as obvious or trivial. It attempts to intimidate the audience into simply accepting the result without evidence by appealing to their ignorance or lack of understanding.
The phrase is often used when the author is an authority in their field, presenting their proof to people who respect a priori the author's insistence of the validity of the proof, while in other cases, the author might simply claim that their statement is true because it is trivial or because they say so. Usage of this phrase is for the most part in good humour, though it can also appear in serious criticism. A proof by intimidation is often associated with phrases such as:
"Clearly..."
"It is self-evident that..."
"It can be easily shown that..."
"... does not warrant a proof."
"The proof is left as an exercise for the reader."
"It is trivial..."
Outside mathematics, "proof by intimidation" is also cited by critics of junk science, to describe cases in which scientific evidence is thrown aside in favour of dubious arguments—such as those presented to the public by articulate advocates who pose as experts in their field.
Proof by intimidation may also back valid assertions. Ronald A. Fisher claimed in the book credited with the new evolutionary synthesis, "...by the analogy of compound interest the present value of the future offspring of persons aged x is easily seen to be...", thence presenting a novel integral-laden definition of reproductive value. At this, Hal Caswell remarked, "With all due respect to Fisher, I have yet to meet anyone who finds this equation 'easily seen.'" Valid proofs were provided by subsequent researchers such as Leo A. Goodman (1968).
In a memoir, Gian-Carlo Rota claimed that the expression "proof by intimidation" was coined by Mark Kac, to describe a technique used by William Feller in his lectures:
See also
References
Professional humor
Mathematical proofs
In-jokes
Mathematical humor
English phrases | Proof by intimidation | [
"Mathematics"
] | 464 | [
"nan"
] |
15,889,734 | https://en.wikipedia.org/wiki/Construction%20trailer | Construction trailers are mobile structures (trailers) used to accommodate temporary offices, dining facilities and storage of building materials during construction projects.
Hook-ups
Typically, trailers need to be equipped with telephone lines and electrical power. Lavatories are usually provided for separately. They are often skid-mounted, on trailers, or put on piles. Construction trailers are often manufactured using traditional stick-frame construction. Intermodal containers are also being converted into construction trailers.
Use in different countries
United States
Municipalities can require the use of construction trailers to be subject to permit proceedings. The City of Fremont, California, for example, publishes its permit requirements on its municipal website.
Enclosed Cargo Trailers are a very popular tool used by many in the construction industry. Keeping equipment and materials clean and dry are a high priority to anyone in the construction industry. These trailers are very user friendly and are multipurpose. Hauling generators, ladders, air compressors and other small to medium sized power tools from one job site to the next is a necessity.
Construction trailers are ordinarily moved by heavy trucks but may also be moved by rail.
Europe
There are people in Europe, especially in German-speaking Europe, who live in trailers of this type, and in German there are words for a congregation of these trailers, Bauwagenplatz and Wagenburg. These trailers, usually lacking modern-day comforts like heating, electricity, toilets and running water, have become a popular form of eco-friendly alternative lifestyle among people mainly from hippie, punk and environmentalist subcultures. The scene bears similarities and can be seen as a European counterpart to housetruckers and the Tiny-house movement.
In 2008 Norwegian media reported that two construction sites (of Byggmester Harald Langemyhr AS) had been housing Polish workers in construction trailers — 4 workers in each.
See also
Alternative housing
Fulltiming
Mobile home
Portable building
Tiny home movement
Housetruckers
Vandwelling
References
External links
Alberta Heritage treatise on construction trailers
Article on construction site security and theft, including trailer contents
House types
Building engineering
Trailers | Construction trailer | [
"Engineering"
] | 422 | [
"Building engineering",
"Civil engineering",
"Architecture"
] |
15,889,847 | https://en.wikipedia.org/wiki/He%20Xiantu | He Xiantu (; born September 28, 1937), also romanized as Xian-Tu He, is a Chinese nuclear and theoretical physicist. He is the chief scientist of many Chinese national nuclear research and development programs. He designed the first neutron bomb in China.
Career
Born in Zhenhai, Ningbo, Zhejiang Province, he studied mathematics and physics, and graduated from the Department of Physics, Zhejiang University in 1962.
He served for a long time in the physical institutes of the Chinese Academy of Engineering and Physics, and he is the former deputy director of the Institute of Applied Physics and Computational Mathematics (IAPCM), Beijing. He currently is the chief scientist of National 863 Program Hi-Tech Inertial Confinement Fusion (ICF) Project and the chief scientist of IAPCM. He also holds the professorship and the dean position of the College of Science, Zhejiang University. He became an academician of the Chinese Academy of Sciences in 1995's election.
He is a member of the Expert Committee of Nonlinear Science, Major State Basic Research. He made great contributions to the development of nuclear weapons in China. He has been long working on inertial confinement fusion ICF model, nonequilibrium statistical physics, and nonlinear plasma physics.
Awards and honors
Asteroid 79286 Hexiantu was named in his honor. The official naming citation was published by the Minor Planet Center on 25 September 2018 (). In July 2019, he was awarded the Edward Teller Medal of the American Nuclear Society "for his outstanding leadership in the development of inertial confinement fusion (ICF) study and his significant contribution to target physics and high energy density physics".
References
External links
The Holeung Ho Lee Foundation
He Xiantu's homepage
China Vitae - Biography of He Xiantu
CESC-ZJU people – Xiantu HE
1937 births
Living people
Chinese nuclear physicists
Educators from Ningbo
Members of the Chinese Academy of Sciences
Physicists from Zhejiang
Scientists from Ningbo
Theoretical physicists
Zhejiang University alumni
Academic staff of Zhejiang University | He Xiantu | [
"Physics"
] | 419 | [
"Theoretical physics",
"Theoretical physicists"
] |
15,890,221 | https://en.wikipedia.org/wiki/Twistor%20correspondence | In mathematical physics, the twistor correspondence (also known as Penrose–Ward correspondence) is a bijection between instantons on complexified Minkowski space and holomorphic vector bundles on twistor space, which as a complex manifold is , or complex projective 3-space. Twistor space was introduced by Roger Penrose, while Richard Ward formulated the correspondence between instantons and vector bundles on twistor space.
Statement
There is a bijection between
Gauge equivalence classes of anti-self dual Yang–Mills (ASDYM) connections on complexified Minkowski space with gauge group (the complex general linear group)
Holomorphic rank n vector bundles over projective twistor space which are trivial on each degree one section of .
where is the complex projective space of dimension .
Applications
ADHM construction
On the anti-self dual Yang–Mills side, the solutions, known as instantons, extend to solutions on compactified Euclidean 4-space. On the twistor side, the vector bundles extend from to , and the reality condition on the ASDYM side corresponds to a reality structure on the algebraic bundles on the twistor side. Holomorphic vector bundles over have been extensively studied in the field of algebraic geometry, and all relevant bundles can be generated by the monad construction also known as the ADHM construction, hence giving a classification of instantons.
References
Mathematical physics | Twistor correspondence | [
"Physics",
"Mathematics"
] | 281 | [
"Applied mathematics",
"Theoretical physics",
"Mathematical physics"
] |
15,890,311 | https://en.wikipedia.org/wiki/Underdetermined%20system | In mathematics, a system of linear equations or a system of polynomial equations is considered underdetermined if there are fewer equations than unknowns (in contrast to an overdetermined system, where there are more equations than unknowns). The terminology can be explained using the concept of constraint counting. Each unknown can be seen as an available degree of freedom. Each equation introduced into the system can be viewed as a constraint that restricts one degree of freedom.
Therefore, the critical case (between overdetermined and underdetermined) occurs when the number of equations and the number of free variables are equal. For every variable giving a degree of freedom, there exists a corresponding constraint removing a degree of freedom. The underdetermined case, by contrast, occurs when the system has been underconstrained—that is, when the unknowns outnumber the equations.
Solutions of underdetermined systems
An underdetermined linear system has either no solution or infinitely many solutions.
For example,
is an underdetermined system without any solution; any system of equations having no solution is said to be inconsistent. On the other hand, the system
is consistent and has an infinitude of solutions, such as , , and . All of these solutions can be characterized by first subtracting the first equation from the second, to show that all solutions obey ; using this in either equation shows that any value of y is possible, with .
More specifically, according to the Rouché–Capelli theorem, any system of linear equations (underdetermined or otherwise) is inconsistent if the rank of the augmented matrix is greater than the rank of the coefficient matrix. If, on the other hand, the ranks of these two matrices are equal, the system must have at least one solution; since in an underdetermined system this rank is necessarily less than the number of unknowns, there are indeed an infinitude of solutions, with the general solution having k free parameters where k is the difference between the number of variables and the rank.
There are algorithms to decide whether an underdetermined system has solutions, and if it has any, to express all solutions as linear functions of k of the variables (same k as above). The simplest one is Gaussian elimination. See System of linear equations for more details.
Homogeneous case
The homogeneous (with all constant terms equal to zero) underdetermined linear system always has non-trivial solutions (in addition to the trivial solution where all the unknowns are zero). There are an infinity of such solutions, which form a vector space, whose dimension is the difference between the number of unknowns and the rank of the matrix of the system.
Underdetermined polynomial systems
The main property of linear underdetermined systems, of having either no solution or infinitely many, extends to systems of polynomial equations in the following way.
A system of polynomial equations which has fewer equations than unknowns is said to be underdetermined. It has either infinitely many complex solutions (or, more generally, solutions in an algebraically closed field) or is inconsistent. It is inconsistent if and only if is a linear combination (with polynomial coefficients) of the equations (this is Hilbert's Nullstellensatz). If an underdetermined system of t equations in n variables (t < n) has solutions, then the set of all complex solutions is an algebraic set of dimension at least . If the underdetermined system is chosen at random the dimension is equal to with probability one.
Underdetermined systems with other constraints and in optimization problems
In general, an underdetermined system of linear equations has an infinite number of solutions, if any. However, in optimization problems that are subject to linear equality constraints, only one of the solutions is relevant, namely the one giving the highest or lowest value of an objective function.
Some problems specify that one or more of the variables are constrained to take on integer values. An integer constraint leads to integer programming and Diophantine equations problems, which may have only a finite number of solutions.
Another kind of constraint, which appears in coding theory, especially in error correcting codes and signal processing (for example compressed sensing), consists in an upper bound on the number of variables which may be different from zero. In error correcting codes, this bound corresponds to the maximal number of errors that may be corrected simultaneously.
See also
Overdetermined system
Regularization (mathematics)
References
Linear algebra
Equations | Underdetermined system | [
"Mathematics"
] | 918 | [
"Linear algebra",
"Equations",
"Mathematical objects",
"Algebra"
] |
15,890,606 | https://en.wikipedia.org/wiki/R%20Canum%20Venaticorum | R Canum Venaticorum is a Mira variable star in the constellation Canes Venatici. It ranges between magnitudes 6.5 and 12.9 over a period of approximately 329 days. It is too faint to be seen with the naked eye, but when it is near its maximum brightness, it can be seen with binoculars.
Thomas E. Espin discovered this variable star, in 1888. It appeared with its variable star designation, R Canum Venaticorum, in Annie Jump Cannon's 1907 work, Second Catalogue of Variable Stars.
References
Mira variables
Canes Venatici
Canum Venaticorum, R
120499
M-type giants
067410
Durchmusterung objects
Emission-line stars | R Canum Venaticorum | [
"Astronomy"
] | 152 | [
"Canes Venatici",
"Constellations"
] |
15,890,853 | https://en.wikipedia.org/wiki/Bateman%20transform | In the mathematical study of partial differential equations, the Bateman transform is a method for solving the Laplace equation in four dimensions and wave equation in three by using a line integral of a holomorphic function in three complex variables. It is named after the mathematician Harry Bateman, who first published the result in .
The formula asserts that if ƒ is a holomorphic function of three complex variables, then
is a solution of the Laplace equation, which follows by differentiation under the integral. Furthermore, Bateman asserted that the most general solution of the Laplace equation arises in this way.
References
.
.
Harmonic analysis
Integral geometry
Partial differential equations
Several complex variables | Bateman transform | [
"Mathematics"
] | 135 | [
"Mathematical analysis",
"Functions and mappings",
"Mathematical analysis stubs",
"Several complex variables",
"Mathematical objects",
"Mathematical relations"
] |
15,891,359 | https://en.wikipedia.org/wiki/Gi-Fi | Gi-Fi or gigabit wireless refers to wireless communication at a bit rate of at least one gigabit per second (Gbit/s).
By 2004 some trade press used the term "Gi-Fi" to refer to faster versions of the IEEE 802.11 standards marketed under the trademark Wi-Fi.
In 2008 researchers at the University of Melbourne demonstrated a transceiver on a single integrated circuit (chip) operating at 60 GHz on the CMOS process, allowing wireless communication speeds of up to 5Gbit/s within a range. Some press reports called this "GiFi". It was developed by the Melbourne University-based laboratories of NICTA (National ICT Australia Limited).
In 2009, the Wireless Gigabit Alliance was formed to promote the technology. It used the term "WiGig" which avoided trademark confusion.
References
Wireless networking | Gi-Fi | [
"Technology",
"Engineering"
] | 176 | [
"Computing stubs",
"Wireless networking",
"Computer networks engineering",
"Computer network stubs"
] |
15,891,439 | https://en.wikipedia.org/wiki/Gigabit%20wireless | Gigabit wireless is the name given to wireless communication systems whose data transfer speeds reach or exceed one gigabit (one billion bits) per second. Such speeds are achieved with complex modulations of the signal, such as quadrature amplitude modulation (QAM) or signals spanning many frequencies. When a signal spans many frequencies, physicists refer that a wide bandwidth signal. In the communication industry, many wireless internet service providers and cell phone companies deploy wireless radio frequency antennas to backhaul core networks, connect businesses, and even individual residential homes.
Common frequencies and bands
In general, indoor protocols follow a cross-vendor standard and communicate in the unlicensed 2.4 GHz, 5 GHz, and (soon) 60 GHz bands.
The outdoor carrier link protocols vary widely and are not compatible across vendors (and often models from the same vendor).
Note: the higher bandwidth devices require a less complex modulation to achieve high speeds.
Wireless broadband
Internet service providers (ISP's) are looking for ways to expand gigabit per second (Gbit/s) high-speed services to their customers. These can be achieved through fiber to the premises broadband network architecture, or a more affordable alternative using fixed wireless in the last mile in combination with the fiber networks in the middle mile in order to reduce the costs of trenching fiber optic cables to the users. In the United States, 60 GHz V band is unlicensed. This makes the V band an appealing choice to be used as fixed wireless access for Gbit/s services to connect to homes and businesses. Similarly, 70/80 GHz E band is lightly licensed which can be more accessible to more providers to provide such services.
There had been some early adopters of the hybrid fiber-wireless approach to provide Gbit/s services to customers. One of those ISP's was Webpass, a company founded in 2003 in San Francisco as a wireless ISP focusing on buildings in big cities. Since then, Webpass had been increasing the speeds along with improved wireless technologies. By 2015, Webpass offered 1 Gbit/s connections to commercial customers, however, the residential customers were limited to speeds of up to 500 Mbit/s to share the 1 Gbit/s wireless link among many residents in the same building. The company utilized a combination of various licensed and unlicensed bands.
In January 2016, a startup company Starry from Boston introduced Starry Point with the goal to provide Gbit/s speed internet wirelessly to homes. The device is a fixed wireless unit attached to a window as an access point to connect to Starry core networks using a millimetre wave band communication. The company did not reveal the details of the band, but claimed to be "the world’s first millimeter wave band active phased array technology for consumer internet communications". However, in January 2018, at the time that the company announced the expansion of its beta service to cover 3 cities: Boston, Los Angeles, and Washington, DC, the speeds were still limited to up to 200 Mbit/s.
In June 2016, Google Fiber acquired Webpass to boost its effort in its experiments with wireless technologies. As a result, Google Fiber put its effort on fiber to the premises on hold to explore more on the cheaper wireless alternative. By early 2017, the Webpass division of Google Fiber expanded 1 Gbit/s wireless service to customers in many cities in the United States.
In November 2016, Atlas Networks, an ISP that serves Seattle, deployed its V-band Gbit/s service to customers within the to its fiber networks. The maximum throughput for each connection was 1 gigabit per second.
In October 2017, Cloudwifi, a startup ISP based in Kitchener, Ontario started using 60 GHz band fixed wireless to provide Gbit/s connectivity to customers within the range of its fiber connection points.
In October 2017, Newark Fiber enabled its first customer in Newark, New Jersey with 10 Gbit/s fixed wireless service. Newark Fiber used V-band 10 Gbit/s transmitters with the distance of up to .
References
Wireless networking
Telecommunication services | Gigabit wireless | [
"Technology",
"Engineering"
] | 837 | [
"Wireless networking",
"Computer networks engineering"
] |
15,892,139 | https://en.wikipedia.org/wiki/Patient%20registration | Patient registration is used to correlate the reference position of a virtual 3D dataset gathered by computer medical imaging with the reference position of the patient. This procedure is crucial in computer assisted surgery, in order to insure the reproducitibility of the preoperative registration and the clinical situation during surgery.
The use of the term "patient registration" out of this context can lead to a confusion with the procedure of registering a patient into the files of a medical institution.
In computer assisted surgery, the first step is to gather a 3D dataset that reproduces with great accuracy the geometry of the normal and pathological tissues in the region that has to be operated on. This is mainly obtained by using CT or MRI scans of that region. The role of patient registration is to obtain a close-to-ideal reference reproducibility of the dataset – in order to correlate the position (offset) of the gathered dataset with the patient's position during the surgical intervention. Patient registration (1) eliminates the necessity of maintaining the same strict position of the patient during both preoperative scanning and surgery, and (2) provides the surgical robot the necessary reference information to act accurately on the patient, even if he has (been) moved during the intervention.
Application
Patient registration was used mostly in head surgery – oral and maxillofacial surgery, neurosurgery, otolaryngology. With the advent of marker- and markerless-registration, the concept has been extended for abdominal surgery.
Using headframes
The first attempts in 3D mapping of human tissues were made by V. Horsley and R. Clarke in 1906. They have built a rectangular stereotactic headframe that had to be fixed to the head. It was based on cartesian principles and allowed them to accurately and reproductibly guide needle-like electrodes for neurophysiological experiments. They have experimented animals and were able to contribute to the mapping of the cerebellum. Improved versions of the Horsley–Clarke apparatus are still in used today in experimental neurosurgery.
The first stereotactic device for humans was also developed in neurosurgery, by E. Spiegel and H. Wycis in 1947. It was used for surgical treatment of Parkinson's disease and, during time, its applicability was extended for the surgical treatment of tumors, vascular malformations, functional neurosurgery etc. The system was based both on headframes and X-ray images taken for all three planes of space.
Further development of stereotactic surgery was made by Brown, Roberts and Wells in 1980. They have developed a halo ring that was applied on the skull, during a CT scan and neurosurgical interventions. This method provided improved surgical guidance and was in fact the first development of computer guided surgery.
Patient registration for the head area has developed for nearly two decades on the same principle of combining CT scans with mechanical reference devices such as headframes or halo rings. But the clinical experience showed that headgear is very uncomfortable to wear and even impossible to apply on little children, because their lack of cooperation; furthermore, the headframes can create artifacts in preoperative data gathering, or during surgery.
Reference markers
Skin
In 1986, a different approach was developed by Roberts und Strohbehn. They have used as landmarks several markers on the patient's skin both preoperative CT registration, and intraoperatively. This was a new current of the time in patient registration. Still, the method is time-consuming, and the exact reproducitibility of the marker positions is questionable.
Bone
The bony structures can provide a much better stability and reproducibility of the landmarks for patient registration. Based on this concept, a further technique was used: to implant temporary markers into bone structures that are superficial to the skin, under local anestesia. This was also combined with surface markers and CT registration. The technique has the disadvantage of a further minimal surgical procedure of placing the bone implants, with some risk of infection for the patient.
Dental splint markers
Dental splints have been traditionally used for transferring and reproducing 3D reference landmarks for positioning cast models in articulators – in dental prosthetics, orthodontics and orthognathic surgery. By applying several infrared markers on the splints and using an infrared camera, a better registration was obtained.
Markerless patient registration
Anatomical landmarks
The first attempts, based on the identification of anatomical landmarks were made by Caversaccio and Zulliger. The method was based on identifying certain antropometrical points and other anatomical landmarks on the skull, in correlation with the CT registration. But the landmarks cannot be exactly pointed out and reproduced during patient dataset registration and surgery, therefore the method is not precise enough.
Surface registration
Since 1998, new procedures have been developed by Marmulla and co-workers, using a different approach to the problem. Both during CT dataset gathering and surgical intervention, the patient registration was made by registering complete areas and surfaces, instead of distinctive surface markers. This was achieved by using laser scanners and a small guiding transmitter. The precision of the patient registration was significantly improved with this method.
Based on this concept, several registration and navigation systems were built by the same team. The Surgical Segment Navigator (SSN and SSN++) is such a system, developed for the first time for oral and maxillofacial surgery. This system correlates three different coordinate sets: CT data set, surface laser scan data set and the dataset produced by a small guiding transmitter, placed on the patient's head. The Laboratory Unit for Computer-Assisted Surgery (LUCAS) is used for planning surgery in the laboratory. This technological and surgical advance has permitted the elimination of mechanical guidance systems and improved the accuracy of the determinations, and thus the surgical act.
A research group at Ryerson University (now Toronto Metropolitan University) developed a method to use optical topographical imaging (OTI) to create a 3D model of the surface of open surgical sites and perform surface registration to CT and MRI data sets for neurosurgical navigation. The OTI technology is being licensed by 7D Surgical for their navigation platform.
References
Surgery
Neurosurgery
Otorhinolaryngology
Computer-assisted surgery
Health informatics | Patient registration | [
"Biology"
] | 1,311 | [
"Health informatics",
"Medical technology"
] |
15,892,469 | https://en.wikipedia.org/wiki/Ancestral%20relation | In mathematical logic, the ancestral relation (often shortened to ancestral) of a binary relation R is its transitive closure, however defined in a different way, see below.
Ancestral relations make their first appearance in Frege's Begriffsschrift. Frege later employed them in his Grundgesetze as part of his definition of the finite cardinals. Hence the ancestral was a key part of his search for a logicist foundation of arithmetic.
Definition
The numbered propositions below are taken from his Begriffsschrift and recast in contemporary notation.
A property P is called R-hereditary if, whenever x is P and xRy holds, then y is also P:
An individual b is said to be an R-ancestor of a, written aR*b, if b has every R-hereditary property that all objects x such that aRx have:
The ancestral is a transitive relation:
Let the notation I(R) denote that R is functional (Frege calls such relations "many-one"):
If R is functional, then the ancestral of R is what nowadays is called connected:
Relationship to transitive closure
The Ancestral relation is equal to the transitive closure of . Indeed, is transitive (see 98 above), contains (indeed, if aRb then, of course, b has every R-hereditary property that all objects x such that aRx have, because b is one of them), and finally, is contained in (indeed, assume ; take the property to be ; then the two premises, and , are obviously satisfied; therefore, , which means , by our choice of ). See also Boolos's book below, page 8.
Discussion
Principia Mathematica made repeated use of the ancestral, as does Quine's (1951) Mathematical Logic.
However, the ancestral relation cannot be defined in first-order logic. It is controversial whether second-order logic with standard semantics is really "logic" at all. Quine famously claimed that it was really 'set theory in sheep's clothing.' In his books setting out formal systems related to PM and capable of modelling significant portions of Mathematics, namely - and in order of publication - 'A System of Logistic', 'Mathematical Logic' and 'Set Theory and its Logic', Quine's ultimate view as to the proper cleavage between logical and extralogical systems appears to be that once axioms that allow incompleteness phenomena to arise are added to a system, the system is no longer purely logical.
See also
Begriffsschrift
Gottlob Frege
Transitive closure
References
George Boolos, 1998. Logic, Logic, and Logic. Harvard Univ. Press.
Ivor Grattan-Guinness, 2000. In Search of Mathematical Roots. Princeton Univ. Press.
Willard Van Orman Quine, 1951 (1940). Mathematical Logic. Harvard Univ. Press. .
External links
Stanford Encyclopedia of Philosophy: "Frege's Logic, Theorem, and Foundations for Arithmetic" -- by Edward N. Zalta. Section 4.2.
Binary relations
ja:概念記法 | Ancestral relation | [
"Mathematics"
] | 637 | [
"Mathematical relations",
"Binary relations"
] |
15,892,980 | https://en.wikipedia.org/wiki/Finno-Ugrian%20suicide%20hypothesis | The Finno-Ugrian suicide hypothesis proposes to link genetic ties originating among Finno-Ugric peoples to high rate of suicide, claiming an allele common among them is responsible.
Mari and Udmurts have been found to have a three times higher suicide rate than Finns and Hungarians. It has been thus theorized that such a possible allele may have arisen in those populations.
However, contrary to the hypothesis, available contemporary (1990–1994) suicide rates in the United States were uniformly negatively associated with the proportion of the population comprising people of self-reported Hungarian, Lithuanian, Polish, Russian, Slovakian, or Ukrainian descent. The findings of this first test outside Europe are therefore conflicting. A proposal based on the geographical study approach is offered to further the progress of investigations into the genetics of suicide.
See also
Human genetic variation
Finnish heritage disease
Gloomy Sunday
List of countries by suicide rate
References
Behavioural genetics
Behavioural sciences
Finno-Ugric peoples
Suicide | Finno-Ugrian suicide hypothesis | [
"Biology"
] | 200 | [
"Behavioural sciences",
"Behavior",
"Human behavior",
"Suicide"
] |
15,893,082 | https://en.wikipedia.org/wiki/Tui%20mine | The Tui mine is an abandoned mine on the western slopes of Mount Te Aroha in the Kaimai Range of New Zealand. It was considered to be the most contaminated site in the country, following the cleanup of the former Fruitgrowers Chemical Company site at Māpua, Nelson.
History
Tui mine was in production by 1881. An aerial ropeway on 12 towers was built in 1889. A road was built in 1950, when the mine was said to be above sea level.
In the 1960s, the Tui mine extracted copper, lead and zinc sulphides, but had a problem with them being contaminated with mercury. The mine was abandoned in 1973, after the mining company Norpac Mining went bankrupt. The machinery was sold to the Mineral Resources (NZ) mine at Waihi, but waste, rock ore dumps and mine tailings were left behind. The tailings have significant amounts of zinc and cadmium. The mine tailings are stored behind a dam in a large pool-like area which has an oxidised, solid surface layer. The dam contains over 100,000 cubic metres of very acidic, sulphide-rich tailings. In 1997, there had been no natural plant recolonisation on the tailings for more than 20 years.
Environmental issues
Waikato University had identified the problem of heavy metals contaminating water by 1984. The tailings dam was considered to be unstable and is leaching various minerals, including heavy metals, into neighbouring waterways and this adversely affected the stream ecology. According to Environment Waikato, the Tui mine had three major environmental impacts;
The heavy metals lead and cadmium were leaching from the tailings dam into the Tunakohoia stream, which flows through land managed by the Department of Conservation and through the centre of the town of Te Aroha. Four years after the mine closed, the Te Aroha town water supply was found to be contaminated with heavy metals leaching from the tailings.
The separate Tui catchment was also contaminated with heavy metals from the tailings dam.
The abandoned mine tailings dam in the Tui catchment was at risk of collapsing in a moderate seismic event or an extreme weather event. That could have caused 90,000 cubic metres of mine waste to liquefy and to flow down the Tui stream near to Te Aroha.
Remediation
In 2007, the New Zealand Government announced that $9.88 million will be made available to clean up the site with the work scheduled to be completed by 2010. In April 2010 it was reported that the estimated cost of the clean-up would be $17.4 million and in 2011 a sum of $16.2 million was allocated to the cleanup with most of the funding from central government. Remediation of the mine site was completed in 2013, at a total cost of $21.7 million.
See also
Mining in New Zealand
Environmental issues in New Zealand
References
Environmental issues in New Zealand
Te Aroha
Underground mines in New Zealand
Environment of Waikato
Tailings dams | Tui mine | [
"Technology",
"Engineering"
] | 619 | [
"Tailings dams",
"Mining engineering",
"Hazardous waste",
"Mining equipment"
] |
15,893,225 | https://en.wikipedia.org/wiki/Competitions%20and%20prizes%20in%20artificial%20intelligence | There are a number of competitions and prizes to promote research in artificial intelligence.
General machine intelligence
The David E. Rumelhart Prize is an annual award for making a "significant contemporary contribution to the theoretical foundations of human cognition". The prize is $100,000.
The Human-Competitive Award is an annual challenge started in 2004 to reward results "competitive with the work of creative and inventive humans". The prize is $10,000. Entries are required to use evolutionary computing.
The Intel AI Global Impact Festival is an international annual competition held by Intel Corporation for school, and college students with prizes upwards of $15,000. It is about artificial intelligence technology. There are two age brackets in this competition, 13-18 Age Group, and 18 and Above Age Group.
The IJCAI Award for Research Excellence is a biannual award given at the International Joint Conference on Artificial Intelligence (IJCAI) to researchers in artificial intelligence as a recognition of excellence of their career.
The 2011 Federal Virtual World Challenge, advertised by The White House and sponsored by the U.S. Army Research Laboratory's Simulation and Training Technology Center, held a competition offering a total of US$52,000 in cash prize awards for general artificial intelligence applications, including "adaptive learning systems, intelligent conversational bots, adaptive behavior (objects or processes)" and more.
The Machine Intelligence Prize is awarded annually by the British Computer Society for progress towards machine intelligence.
The Kaggle – "the world's largest community of data scientists compete to solve most valuable problems".
Conversational behaviour
The Loebner prize is an annual competition to determine the best Turing test competitors. The winner is the computer system that, in the judges' opinions, demonstrates the "most human" conversational behaviour, they have an additional prize for a system that in their opinion passes a Turing test. This second prize has not yet been awarded.
Automatic control
Pilotless aircraft
The International Aerial Robotics Competition is a long-running event begun in 1991 to advance the state of the art in fully autonomous air vehicles. This competition is restricted to university teams (although industry and governmental sponsorship of teams is allowed). Key to this event is the creation of flying robots which must complete complex missions without any human intervention. Successful entries are able to interpret their environment and make real-time decisions based only on a high-level mission directive (e.g., "find a particular target inside a building having certain characteristics which is among a group of buildings 3 kilometers from the aerial robot launch point"). In 2000, a $30,000 prize was awarded during the 3rd Mission (search and rescue), and in 2008, $80,000 in prize money was awarded at the conclusion of the 4th Mission (urban reconnaissance).
Driverless cars
The DARPA Grand Challenge is a series of competitions to promote driverless car technology, aimed at a congressional mandate stating that by 2015 one-third of the operational ground combat vehicles of the US Armed Forces should be unmanned. While the first race had no winner, the second awarded a $2 million prize for the autonomous navigation of a hundred-mile trail, using GPS, computers and a sophisticated array of sensors. In November 2007, DARPA introduced the DARPA Urban Challenge, a sixty-mile urban area race requiring vehicles to navigate through traffic. In November 2010 the US Armed Forces extended the competition with the $1.6 million prize Multi Autonomous Ground-robotic International Challenge to consider cooperation between multiple vehicles in a simulated-combat situation.
Roborace will be a global motorsport championship with autonomously driving, electric vehicles. The series will be run as a support series during the Formula E championship for electric vehicles. This will be the first global championship for driverless cars.
Data-mining and prediction
The Netflix Prize was a competition for the best collaborative filtering algorithm that predicts user ratings for films, based on previous ratings. The competition was held by Netflix, an online DVD-rental service. The prize was $1,000,000.
The Pittsburgh Brain Activity Interpretation Competition will reward analysis of fMRI data "to predict what individuals perceive and how they act and feel in a novel Virtual Reality world involving searching for and collecting objects, interpreting changing instructions, and avoiding a threatening dog." The prize in 2007 was $22,000.
The Face Recognition Grand Challenge (May 2004 to March 2006) aimed to promote and advance face recognition technology.
The American Meteorological Society's artificial intelligence competition involves learning a classifier to characterise precipitation based on meteorological analyses of environmental conditions and polarimetric radar data.
Cooperation and coordination
Robot football
The RoboCup and Federation of International Robot-soccer Association (FIRA) are annual international robot soccer competitions. The International RoboCup Federation challenge is by 2050 "a team of fully autonomous humanoid robot soccer players shall win the soccer game, comply with the official rule of the FIFA, against the winner of the most recent World Cup."
Logic, reasoning and knowledge representation
The Herbrand Award is a prize given by Conference on Automated Deduction (CADE) Inc. to honour persons or groups for important contributions to the field of automated deduction. The prize is $1000.
The CADE ATP System Competition (CASC) is a yearly competition of fully automated theorem provers for classical first order logic associated with the Conference on Automated Deduction (CADE) and International Joint Conference on Automated Reasoning (IJCAR). The competition was part of the Alan Turing Centenary Conference in 2012, with total prizes of 9000 GBP given by Google.
The SUMO prize is an annual prize for the best open source ontology extension of the Suggested Upper Merged Ontology (SUMO), a formal theory of terms and logical definitions describing the world. The prize is $3000.
The Hutter Prize for lossless compression of human knowledge is a cash prize which rewards compression improvements on a specific 100 MB English text file. The prize awards 500 euros for each one percent improvement, up to €50,000. The organizers believe that text compression and AI are equivalent problems and 3 prizes have been given, at around € 2k.
The Cyc TPTP Challenge is a competition to develop reasoning methods for the Cyc comprehensive ontology and database of everyday common sense knowledge. The prize is 100 euros for "each winner of two related challenges".
The Eternity II challenge was a constraint satisfaction problem very similar to the Tetravex game. The objective is to lay 256 tiles on a 16x16 grid while satisfying a number of constraints. The problem is known to be NP-complete. The prize was US$2,000,000. The competition ended in December 2010.
Games
The World Computer Chess Championship has been held since 1970. The International Computer Games Association continues to hold an annual Computer Olympiad which includes this event plus computer competitions for many other games.
The Ing Prize was a substantial money prize attached to the World Computer Go Congress, starting from 1985 and expiring in 2000. It was a graduated set of handicap challenges against young professional players with increasing prizes as the handicap was lowered. At the time it expired in 2000, the unclaimed prize was 400,000 NT dollars for winning a 9-stone handicap match.
The AAAI General Game Playing Competition is a competition to develop programs that are effective at general game playing. Given a definition of a game, the program must play it effectively without human intervention. Since the game is not known in advance the competitors cannot especially adapt their programs to a particular scenario. The prize in 2006 and 2007 was $10,000.
The General Video Game AI Competition (GVGAI) poses the problem of creating artificial intelligence that can play a wide, and in principle unlimited, range of games. Concretely, it tackles the problem of devising an algorithm that is able to play any game it is given, even if the game is not known a priori. Additionally, the contests poses the challenge of creating level and rule generators for any game is given. This area of study can be seen as an approximation of General Artificial Intelligence, with very little room for game dependent heuristics. The competition runs yearly in different tracks: single player planning, two-player planning, single player learning, level and rule generation, and each track prizes ranging from 200 to 500 US dollars for winners and runner-ups.
The 2007 Ultimate Computer Chess Challenge was a competition organised by World Chess Federation that pitted
Deep Fritz against Deep Junior. The prize was $100,000.
The annual Arimaa Challenge offered a $10,000 prize until the year 2020 to develop a program that plays the board game Arimaa and defeats a group of selected human opponents. In 2015, David Wu's bot bot_sharp beat the humans, losing only 2 games out of 9. As a result, the Arimaa Challenge was declared over and David Wu received the prize of $12,000 ($2,000 being offered by third-parties for 2015's championship).
2K Australia is offering a prize worth A$10,000 to develop a game-playing bot that plays a first-person shooter video game which can convince a panel of judges that it is a human player. The competition started in 2008 and was won in 2012. A new competition is planned for 2014.
The Google AI Challenge was a bi-annual online contest organized by the University of Waterloo Computer Science Club and sponsored by Google that ran from 2009 to 2011. Each year a game was chosen and contestants submitted specialized automated bots to play against other competing bots.
Cloudball had its first round in Spring 2012 and finished on June 15. It is an international artificial intelligence programming contest, where users continuously submit the actions their soccer teams will take in each time step, in simple high level C# code.
The International Olympiad in Artificial Intelligence for high-school students was established in 2024 and consists of two rounds: in the scientific round, participants solve problems in different subfields of AI, and in the practical round, participants use existing AI tools to produce a visual result.
See also
Artificial intelligence
Progress in artificial intelligence
Glossary of artificial intelligence
References
Artificial intelligence competitions
Computer science competitions
Science and technology awards | Competitions and prizes in artificial intelligence | [
"Technology"
] | 2,058 | [
"Science and technology awards"
] |
15,893,474 | https://en.wikipedia.org/wiki/Eucomed | Eucomed was the organisation that represented the interests of the medical device industry in Europe. It represents directly and indirectly 4,500 designers, manufacturers and suppliers of medical technology used in the diagnosis, prevention, treatment and management of disease and disability. Eucomed represents a total of 11,000 legal entities in Europe. It is now part of MedTech Europe.
Structure
Among its members, there are 24 national medical technology associations and 62 medical technology companies, comprising approximately 70% of the European market. Eucomed has over 65 expert groups. These groups deal with regulatory, economic, public affairs, international and legal affairs topics. Eucomed represents several sectors within medical technology such as ophthalmology, cardiovascular medicine, orthopaedics, advanced wound care and Community Care.
Activities
Eucomed's main mission is to advocate for the medical device industry at the European level. It engages with policymakers with European institutions and EU member states, patient groups, and medical associations. It also represents the interests of the European medical device industry in relations with foreign markets. Eucomed regularly organises meetings and workshops for members and stakeholders. It is currently lobbying for the interests of the European medical device industry in the revision of the European medical device directive.
Eucomed conducts substantial research on the European medical device market. Along with the LSE and Bocconi University, Eucomed supports EHTI, an institute dedicated to that end.
MedTech Europe
Eucomed is now part of MedTech Europe.
MedTech Forum
The MedTech Europe alliance members organise the largest health and medical technology industry conference in Europe, the MedTech Forum. The conference is attended by policymakers, scientific communities, patient representatives, healthcare professionals, academics and representatives of the global medical technology industry.
References
Medical equipment | Eucomed | [
"Biology"
] | 363 | [
"Medical equipment",
"Medical technology"
] |
15,893,489 | https://en.wikipedia.org/wiki/Telecompressor | A telecompressor or focal reducer is an optical element used to reduce focal length, increase lens speed, and in some instances improve optical transfer function (OTF) performance. It is also widely known under the name “Speed Booster”, which is the commercial name of a line of telecompressors by the manufacturer Metabones. Popular applications include photography, videography, and astrophotography. In astrophotography, these qualities are most desirable when taking pictures of nearby large objects, such as nebulae. The effects and uses of the telecompressor are largely opposite to those of the teleconverter or Barlow lens. A combined system of a lens and a focal reducer has smaller back focus than the lens alone; this places restrictions on lenses and cameras that focal reducer might be used with.
Lens adapters that include telecompressors are useful with digital mirrorless cameras. By combining a telecompressor within a lens adapter, mirrorless cameras can use the lenses of both digital single-lens reflex cameras (DSLRs) and film-based SLR (Single-lens reflex cameras).
Calculating focal reduction
For a refractor telescope or simple camera lens, the new effective focal length fn is given by:
where
fo = original focal length of telescope,
d = distance from telecompressor to image plane, and
fr = focal length of telecompressor.
For a reflecting telescope, the calculation is the same. However, since the telecompressor increases the field of view, there could be vignetting in the image, depending on the sizes of the secondary mirror and the telescope tube.
For a catadioptric system that has a combination of mirror and lens, the determination of reduction is more complicated, due to the fact that the telescope has a variable focal length, where the imaging plane can move along the axis of the imaging system. As the addition of the telecompressor will increase the necessary back focus, the original focal length will increase by a certain amount, and then this new focal length would be used in the above formula.
Keplerian (relay) telecompressors
Telecompressors were used in early digital SLR systems like the Minolta RD-175 and the Nikon E series. The technology of the time used relatively small sensor sizes, so lenses designed for 35 mm film could not be used with their native field of view without additional optics used. Implementing a telecompressor helped to mitigate these limitations. One effect of a telecompressor is that it reduces the diameter of the image circle, which means that a lens meant for a larger format can be used on a smaller sensor with a higher crop factor.
See also
Barlow lens
Teleconverter
Convertible lens
References
Astronomical instruments
Photography equipment | Telecompressor | [
"Astronomy"
] | 561 | [
"Astronomical instruments"
] |
15,893,520 | https://en.wikipedia.org/wiki/Chudnovsky%20algorithm | The Chudnovsky algorithm is a fast method for calculating the digits of , based on Ramanujan's formulae. Published by the Chudnovsky brothers in 1988, it was used to calculate to a billion decimal places.
It was used in the world record calculations of 2.7 trillion digits of in December 2009, 10 trillion digits in October 2011, 22.4 trillion digits in November 2016, 31.4 trillion digits in September 2018–January 2019, 50 trillion digits on January 29, 2020, 62.8 trillion digits on August 14, 2021, 100 trillion digits on March 21, 2022, 105 trillion digits on March 14, 2024, and 202 trillion digits on June 28, 2024.
Algorithm
The algorithm is based on the negated Heegner number , the j-function , and on the following rapidly convergent generalized hypergeometric series:A detailed proof of this formula can be found here:
This identity is similar to some of Ramanujan's formulas involving , and is an example of a Ramanujan–Sato series.
The time complexity of the algorithm is .
Optimizations
The optimization technique used for the world record computations is called binary splitting.
Binary splitting
A factor of can be taken out of the sum and simplified to
Let , and substitute that into the sum.
can be simplified to , so
from the original definition of , so
This definition of is not defined for , so compute the first term of the sum and use the new definition of
Let and , so
Let and
can never be computed, so instead compute and as approaches , the approximation will get better.
From the original definition of ,
Recursively computing the functions
Consider a value such that
Base case for recursion
Consider
Python code
#Note: For extreme calculations, other code can be used to run on a GPU, which is much faster than this.
import decimal
def binary_split(a, b):
if b == a + 1:
Pab = -(6*a - 5)*(2*a - 1)*(6*a - 1)
Qab = 10939058860032000 * a**3
Rab = Pab * (545140134*a + 13591409)
else:
m = (a + b) // 2
Pam, Qam, Ram = binary_split(a, m)
Pmb, Qmb, Rmb = binary_split(m, b)
Pab = Pam * Pmb
Qab = Qam * Qmb
Rab = Qmb * Ram + Pam * Rmb
return Pab, Qab, Rab
def chudnovsky(n):
"""Chudnovsky algorithm."""
P1n, Q1n, R1n = binary_split(1, n)
return (426880 * decimal.Decimal(10005).sqrt() * Q1n) / (13591409*Q1n + R1n)
print(f"1 = {chudnovsky(2)}") # 3.141592653589793238462643384
decimal.getcontext().prec = 100 # number of digits of decimal precision
for n in range(2,10):
print(f"{n} = {chudnovsky(n)}") # 3.14159265358979323846264338...
Notes
See also
Ramanujan–Sato series
Bailey–Borwein–Plouffe formula
Borwein's algorithm
Approximations of π
External links
How is π calculated to trillions of digits?
References
Pi algorithms | Chudnovsky algorithm | [
"Mathematics"
] | 774 | [
"Pi",
"Pi algorithms"
] |
11,704,197 | https://en.wikipedia.org/wiki/Cercospora%20sojina | Cercospora sojina is a fungal plant pathogen which causes frogeye leaf spot of soybeans. Frog eye leaf spot is a major disease on soybeans in the southern U.S. and has recently started to expand into the northern U.S. where soybeans are grown. The disease is also found in other soybean production areas of the world.
Host and symptomalogy
The soybean is the main host of this pathogen. When the pathogen occurs on soybeans, it causes small leaf lesions. These lesions, mostly found on upper leaf surfaces, are irregularly circular and consist of red-brown to purple colored borders. The inside of the lesion is often a gray to tan color. When the lesions mature, they are paper thin and the infected leaves appear tattered and weathered. The disease can lead to premature defoliation. The Frogeye leaf spot can also form on the pods and stems of highly susceptible cultivars. Oval and circular lesions that form on the pods and stems have dark-colored margins and light gray to reddish-brown color on the inside. If the pod becomes infected, the seeds can also become infected but may be symptomless. If they do show symptoms, gray blotches form on the seed and a cracked seed coat often occurs.
The plant is most susceptible to an infection when the leaves are young and expanding or if the leaves are old and senescing. With this range of susceptibility, the disease can occur several times throughout the plant canopy if the environment is ideal for the pathogen at each leaf layer emergence. This leads to a layered section of disease on one plant. Within a field, the disease often occurs in patches either small or large throughout the field. During Stages R1-R6 in soybeans and after a period of frequent rainfall is the best time to scout on frogeye leaf spot. This disease is typically present mid to late season.
Disease cycle
Cercospora sojina, the causal fungal agent, and Frogeye Leaf Spot, the resulting disease, have a polycyclic infection cycle. Within this cycle, the pathogen can infect multiple plants during the growing season. In the winter, the pathogen is present as mycelium in crop residue and in leftover soybeans from the previous harvest. According to Bradley et al., the fungus can remain in plant residue for a minimum of two years (2016).
Conidia is the primary and secondary inoculum of the plant. This asexual structure is produced from conidiophores on infected plant residue (Lin and Kelly, 2018). The conidia can also be moved over short distances by wind currents (Mian et al., 2008). The most suitable conditions for infection are warm and wet weather between 25 and 30 °C with greater than 90% humidity (2018).
Infection can occur at any stage of the soybean growth cycle but occurs most frequently after flowering (Bayer, 2018). The fungus has more of a damaging impact when infection occurs before or at flowering (Lin and Kelly, 2018). Fungal infection occurs with direct contact from an already infected soybean pod but the fungus can also spread from seed to seed during plant growth. If infection does occur, external plant damage can be seen one to two weeks after contact with the pathogen.
In addition to seed infection, dark narrow lesions on stems and long to circular red-brown lesions on pods can also appear later in the growing season (Bayer, 2018). Soybean debris during the growing season contributes to the second inoculum of the disease. Managing the pathogen is most successful when the disease is recognized close to flowering time and before growth stage R5 or at the beginning of seed development.
Pathogenesis
Cercospora sojina is a fungal pathogen that varies in colony color, growth rate, and spore formation in culture. The main infection structure of the pathogen is the conidia which is produced from light or dark conidiophores and rests on the tip of the structure. The conidia appear translucent and form cylindrical to round tapering shapes. The size varies between 6 micrometers to 40-70 micrometers and depends on how much area is available for growth (Lin and Kelly, 2018). The direct pathogenesis of the fungus is unknown but through genetic analysis a plausible suggestion is made. Certain gene clusters in the fungus genome encode for secondary metabolites, such as mycotoxins and pigments, and virulence effectors. The production of these metabolites is elevated during early infection and most likely play a key role in the fungus and plant interaction (Luo et al., 2017).
More specifically, when comparing nonresistant and resistance strains of the pathogen from China, researchers observed 5 candidate genes that are linked to virulence. The gene's function was related to metabolic mechanisms and the production of metabolites that can cause reduction in host resistant soybean plants (Gu et al., 2020). Cercosporin is one non-specific colored mycotoxin produced in some Cercospora species. It is suggested to play an important role in the virulence of the pathogen. This mycotoxin is a photosensitizer and can cause oxidative damage to cell structures. Genes that encode for this toxin have been found in some genomes of the fungus but no cercosporin has been found in cultured mycelium or infected plant tissue (Luo et al., 2018; Lin and Kelly, 2018).
Environment
Frogeye leaf spot is often found after warm, humid weather conditions. Frequent rainfalls over an extended period of time can also promote the disease to form. The fungus is known to overwinter in infested seeds and crop residue. If a producer has a field with continuous production of soybeans, there is a higher chance of frogeye leaf spot typically present.
Generally, lesions take more than one week to develop after the plant has been infected. This causes the disease to not be visible on the younger leaves of the plant until significantly later. Older leaves are not as susceptible to the disease. In severe conditions lesions can be seen on pods and stems too.
Management
Without proper management there can be various consequences of this disease. Yield loss is a huge impact of this pathogen. If a large amount of lesions are present on the leaves of a soybean there is a loss of leaf area index which in turn results in less photosynthesis. With less photosynthesis, less carbohydrate will be made and the plant will produce less seed. There is also ethylene produced within the leaf spots that stimulates defoliation in the leaves. This will further reduce productivity of the plant.
In order to stop yield loss it is important that various methods are used to manage this disease. These include resistance, seed quality, cultural practices and fungicide use. Resistant cultivars exist and can be planted if a producer knows this disease has been a consistent problem. Instead of saving seed, a producer should plant certified disease free seed to reduce the risk of bringing the pathogen into the field. Seed Quality is important and can prevent the survival stage of the disease cycle.
Rotation with crops not susceptible to the disease, like corn and small grains, can be a form of cultural control of frogeye leaf spot. This will take away the host in the following season so the survival structure will not have a place to go. Using tillage to disturb the pathogen's survival structures will also reduce the disease in the future.
Fungicides can be applied to the foliar from the R1-R4 stage of soybeans (late flowering to pod-filling stages). This kind of application can reduce the incidence and severity of the disease. Yield and seed quality can also be improved. In the United States, Frogeye leaf spot has been reported to have resistance to Quinone outside inhibitors (strobilurins). Using multiple active ingredients for a fungicide application can help prevent resistance. Seed treatments are a preventative method that can reduce the threat frogeye leaf spot.
None of these methods have been proven to be better than others but by using multiple of these management tools a grower will help reduce the amount of inoculum available in the field and assist in protecting the plants from infection.
Significance
The pathogen is a serious concern to soybean farmers and can cause detrimental yield loss during the growing season. Since 2000, the fungus has been present in the northern and southern U.S. states as well as 27 other countries spanning North and South America, Europe Africa and Asia (Lin and Kelly 2018). The fungus is very prevalent in the southern U.S., but in previous years it has spread to northern soybean fields (Smith, 2020). During a wet season, the fungus can cause up to a 30% loss of soybean crop in some fields (Bayer, 2018). Other authors note a yield loss as high as 60% due to the reduction in photosynthetic area, early leaf loss and reduced seed quality (Lin and Kelly, 2018).
Crop reduction from the pathogen can differ each year depending on the environmental conditions. Between 2010 and 2014, bushel loss varied between 3,727 and 18,147 (bushels in thousands) in the United States. Another source states that in Midwestern states between 1996 and 2000, the estimated loss was 460,000 bushels and between 2013 and 2017 the estimated loss was reported as 7,600,000 bushels in the same areas (Stoetzer, 2019).
Attempts to reduce the presence of the fungus have been employed, however, Cercospora sojina still remains a threat to farmers. Resistance to fungicide has already occurred in 13 U.S. states at the end of 2016. New versions of the fungal genome have also been observed across the U.S., Brazil, China and other regions where soybeans are grown that have varying virulence and resistance levels (Lin and Kelly, 2018; Gu et al., 2020). Warmer winter temperatures have been suggested as a possible contributor to an increase in Frogeye Spot disease as well as susceptible soybeans and conservation tillage. If leftover residue from infected plants is not removed and crop rotation does not occur, the fungus will continue to develop into the next growing season.
See also
List of soybean diseases
References
1 Frogeye Leaf Spot." (n.d.): n. pag. University of Tennessee. Institute of Agriculture. Web. 25 Oct. 2016.
http://guide.utcrops.com/soybean/foliar-diseases/frogeye-leaf-spot/
2 "Frogeye Leaf Spot." Frogeye Leaf Spot : Crop Diseases : University of Minnesota Extension. University of Minnesota, n.d. Web. Nov. 2016. <https://web.archive.org/web/20161210174858/http://www.extension.umn.edu/agriculture/crop-diseases/soybean/frogeyeleafspot.html>.
3 Mueller, Daren, Kiersten Wise, Adam Sisson, Damon Smith, Edward Sikora, Carl Bradley, and Alison Roberstson, eds. A Farmer's Guide To Soybean Diseases. St. Paul: American Phytopathological Society, 2016. Print.
4 Mian, Rouf. "Genetic Resistance of Soybean to Frogeye Leaf Spot, Mapping of Rcs3 Gene, and Breeding for Resistance." (n.d.): n. pag. USDA-ARS. Web. 26 Oct. 2016.
5 Smith, Damon. "Frogeye Leaf Spot." WISCONSIN FIELD CROPS PATHOLOGY. University of Wisconsin-Extension, n.d. Web. Nov. 2016. <http://fyi.uwex.edu/fieldcroppathology/soybean_pests_diseases/frogeye-leaf-spot/
6 Westphal, Andreas, T. Scott. Abney, Gregory Shaner Diseases of Soybean: Frogeye Leaf Spot, BP-131-W (n.d.): n. pag. University of Purdue, Aug. 2006. https://www.extension.purdue.edu/extmedia/bp/bp-131-w.pdf.
sojina
Fungal plant pathogens and diseases
Soybean diseases
Fungus species | Cercospora sojina | [
"Biology"
] | 2,577 | [
"Fungi",
"Fungus species"
] |
11,704,554 | https://en.wikipedia.org/wiki/Michael%20Spivey | Michael Spivey (commonly known as Mike Spivey) is a British computer scientist at the University of Oxford.
Spivey was born in 1960 and educated at Archbishop Holgate's Grammar School in York, England. He studied mathematics at Christ's College, Cambridge and then undertook a DPhil in computer science on the Z notation at Wolfson College, Oxford and the Programming Research Group, part of the Oxford University Computing Laboratory.
Mike Spivey is a University Lecturer in Computation at the Oxford University Department of Computer Science and Misys and Anderson Fellow of Computer Science at Oriel College, Oxford. His main areas of research interest are compilers and programming languages, especially logic programming. He wrote an Oberon-2 compiler.
Publications
Understanding Z: A Specification Language and its Formal Semantics, Cambridge University Press, Cambridge Tracts in Theoretical Computer Science, No. 3, 2008. .
The Z Notation: A reference manual, Prentice Hall International Series in Computer Science, 1992. .
An introduction to logic programming through Prolog, Prentice Hall International Series in Computer Science, 1996. .
References
External links
Official home page
Personal home page
1960 births
Living people
People educated at Archbishop Holgate's School
Alumni of Christ's College, Cambridge
Alumni of Wolfson College, Oxford
Fellows of Oriel College, Oxford
English computer scientists
Formal methods people
Logic programming researchers
Computer science writers
Members of the Department of Computer Science, University of Oxford
Programming language researchers
Z notation | Michael Spivey | [
"Mathematics"
] | 295 | [
"Z notation"
] |
11,708,087 | https://en.wikipedia.org/wiki/Minimum%20deviation | In a prism, the angle of deviation () decreases with increase in the angle of incidence () up to a particular angle. This angle of incidence where the angle of deviation in a prism is minimum is called the minimum deviation position of the prism and that very deviation angle is known as the minimum angle of deviation (denoted by , , or ).
The angle of minimum deviation is related with the refractive index as:
This is useful to calculate the refractive index of a material. Rainbow and halo occur at minimum deviation. Also, a thin prism is always set at minimum deviation.
Formula
In minimum deviation, the refracted ray in the prism is parallel to its base. In other words, the light ray is symmetrical about the axis of symmetry of the prism.
Also, the angles of refractions are equal i.e. . The angle of incidence and angle of emergence equal each other (). This is clearly visible in the graph below.
The formula for minimum deviation can be derived by exploiting the geometry in the prism. The approach involves replacing the variables in the Snell's law in terms of the Deviation and Prism Angles by making the use of the above properties.
From the angle sum of ,
Using the exterior angle theorem in ,
This can also be derived by putting in the prism formula:
From Snell's law,
(where is the refractive index, is the Angle of Prism and is the Minimum Angle of Deviation.)
This is a convenient way used to measure the refractive index of a material(liquid or gas) by directing a light ray through a prism of negligible thickness at minimum deviation filled with the material or in a glass prism dipped in it.
Worked out examples:
Answer: 37°, 49°
Solution:
Here, ,
Plugging them in the above formula,
Also,
This is also apparent in the graph below.
Answer: 60°
Solution:
Here,
Using the above formula,
Also, the variation of the angle of deviation with an arbitrary angle of incidence can be encapsulated into a single equation by expressing δ in terms of in the prism formula using Snell's law:
Finding the minima of this equation will also give the same relation for minimum deviation as above.
Putting , we get,
, and by solving this equation we can obtain the value of angle of incidence for a definite value of angle of prism and the value of relative refractive index of the prism for which the minimum angle of deviation will be obtained. The equation and description are given here
For thin prism
In a thin or small angle prism, as the angles become very small, the sine of the angle nearly equals the angle itself and this yields many useful results.
Because and are very small,
Using a similar approach with the Snell's law and the prism formula for an in general thin-prism ends up in the very same result for the deviation angle.
Because , and are small,
From the prism formula,
Thus, it can be said that a thin prism is always in minimum deviation.
Experimental determination
Minimum deviation can be found manually or with spectrometer. Either the prism is kept fixed and the incidence angle is adjusted or the prism is rotated keeping the light source fixed.
Minimum angle of dispersion
The minimum angle of dispersion for white light is the difference in minimum deviation angle between red and violet rays of a light ray through a prism.
For a thin prism, the deviation of violet light, is and that of red light, is . The difference in the deviation between red and violet light, is called the Angular Dispersion produced by the prism.
Applications
One of the factors that causes a rainbow is the bunching of light rays at the minimum deviation angle that is close to the rainbow angle (42°).
It is also responsible for phenomena like halos and sundogs, produced by the deviation of sunlight in mini prisms of hexagonal ice crystals in the air bending light with a minimum deviation of 22°.
See also
Prism
Refraction
Geometrical optics
References
External links
Minimum Deviation Part 1 and Part 2 at Khan Academy
Refraction through a Prism in NCERT Textbook
Minimum Deviation by Prism by Mark A Peterson, Mount Holyoke College
Geometrical optics
Light | Minimum deviation | [
"Physics"
] | 852 | [
"Physical phenomena",
"Spectrum (physical sciences)",
"Electromagnetic spectrum",
"Waves",
"Light"
] |
11,708,150 | https://en.wikipedia.org/wiki/The%20Beast%20%28Revelation%29 | The Beast (, ) may refer to one of three beasts described in the Book of Revelation.
Revelation 12-13 describes these three beasts as follows:
(1) The dragon (later revealed in the text to be Satan)
(2) The beast of the sea (commonly interpreted as the Antichrist) and
(3) The beast of the earth (later revealed in the text to be the False Prophet).
However, many people have different beliefs about the meaning of these beasts.
In Revelation 13:1–10, the beast of the sea rises "out of the sea" and is given authority and power by the dragon. It persecutes God's people in the 2nd part of Revelation 13. To buy and sell, everyone is required to have its name or number on their forehead or right hand (Rev 13:16-17). It speaks blasphemous words against God, will rule the world for 42 months (Revelation 13:5-7), and is described as resembling a leopard, a lion, and a bear— which are three of the animals in Daniel 7. It suffers a fatal head wound which is miraculously healed, bewildering the world's population and causing many to worship it.
In Revelation 13:11–18, the beast of the earth, later known as the false prophet, comes "out of the earth," exercises all the authority of the Sea Beast, forces everyone on earth to worship the Sea Beast, and convinces the people, through signs and wonders, to make an image of the Sea Beast.
In their fight against God, the Sea Beast and the False Prophet ally with the Dragon to persecute the "saints" and those who do not "worship the image of the beast [of the sea]" and influence earthly kings through three unclean spirits to gather for the battle of Armageddon. These two beasts are ultimately defeated by Christ and thrown into the lake of fire mentioned in Revelation 19:18–20, while Satan, the dragon, is imprisoned in the bottomless pit for 1,000 years. After being released from the bottomless pit after the millennial reign, Satan deceives the nations one last time, ultimately ending in Satan being defeated and thrown in the lake of fire.
Book of Revelation
Beast from the Sea
The description of the Sea Beast is found in Revelation chapters thirteen and seventeen. Chapter thirteen gives the fullest description.
It rises out of the sea (Rev 13:1). The four animals of Daniel 7 also arise from the sea, explained as four kingdoms arising from the earth (Dan 7:3, 17). In Revelation, the "many waters" on which the harlot sits are explained as "peoples and multitudes and nations and tongues" (Rev 17:1, 15).
The beast has seven heads and ten horns (Rev 13:1), equal to the total number of heads and horns in Daniel 7, indicating some relationship.
The beast has crowns on its horns (Rev 13:1).
The beast "was like a leopard, and his feet were like those of a bear, and his mouth like the mouth of a lion" (Rev 13:2). These are the first three animals in Daniel 7, but in reverse order.
"The dragon gave him his power and his throne and great authority" (Rev 13:2).
"I saw one of his heads as if it had been slain" (Rev 13:3). Revelation 17 describes these heads as representing kings and also mountains on which the woman sits.
The beast in Revelation 17 also suffers a severe fatal wound to the head.
"His fatal wound was healed" (Rev 13:3).
"The whole earth was amazed and followed after the beast" (Rev 13:4). Similarly, in Revelation 17, when the beast comes out of the abyss, "those who dwell on the earth... will wonder when they see the beast" (Rev 13:8; 17:8).
"They worshiped the dragon because he gave his authority to the beast; and they worshiped the beast" (Rev 13:4). "Worship" is perhaps the key word in Revelation 13. It appears many times. In Revelation 14, three angels warn the world to worship the Creator alone. The end-time may be understood as a crisis over who to worship.
Apart from giving authority to the Sea Beast, the Dragon does nothing in Revelation 13. All the work is done by the Sea Beast, the Earth Beast, and the Image of the Beast. So, the people worship the Beast directly but the Dragon only indirectly.
"There was given to him — a mouth speaking arrogant words and blasphemies... he opened his mouth in blasphemies against God, to blaspheme His name and His tabernacle" (Rev 13:5-6). The 11th horn of Daniel 7 similarly has "a mouth uttering great boasts." "He will speak out against the Most High." (Dan 7:20, 25)
"Authority to act for forty-two months was given to him" (Rev 13:5). He received authority over "the saints" and over all people (Rev 13:7). The 11th horn of Daniel 7 will "wear down the saints of the Highest One ... and they will be given into his hand for a time, times, and half a time" (Dan 7:25). It has been argued that the 42 months are equal to the "time, times, and half a time." (3½ times = 3½ years = 42 months)
Beast from the Earth
The Beast from the Earth is primarily described in Revelation chapter thirteen. This beast comes out of the earth whose overall appearance is not described, other than having "two horns like a lamb", and speaking "like a dragon". His purpose is to promote the authority of the Sea Beast with the ability to perform great signs, even making fire come down out of Heaven. This Earth Beast is also called the false prophet. He speaks like a dragon commanding the people of the Earth to make an image "to" the beast that was wounded by a sword (the Sea Beast). It is declared that anyone who does not worship the Sea Beast or its image would be killed. This lamb-horned beast from the earth also causes all people to receive the mark of the beast "in their right hand or in their forehead."
The Scarlet Beast
Revelation 17 mentions another beast described as "a scarlet coloured beast", although it is most likely the same as the Sea Beast mentioned in Revelation 13.
Just like the Dragon and the Sea Beast, it has seven heads and ten horns (), implying that these three are of the same species. Since there are also seven heads and ten horns among the four animals of Daniel 7, and since the animals of Daniel 7 exist until Christ's return, the seven heads and ten horns of the beasts in Revelation imply that they are related to the animals of Daniel 7.
The scarlet beast is shown being ridden by a harlot who "reigns over the kings of the earth", () whereas the beast of the sea is not described as being ridden, and is given "power and great authority." The seven heads represent both seven mountains and seven kings, and the ten horns are ten kings who have not yet received kingdoms. Of the seven kings, five have fallen, one is, the other has not yet come. The beast itself is an eighth king who is of the seven and "was and is not and shall ascend out of the bottomless pit, and go into perdition."
Image of the Beast
Those who dwell on the earth are deceived into making an image [interpreted as a statue] of the Sea Beast as a means to worship its authority. The false prophet breathes life into the "image of the beast", so that the image becomes alive and is able to speak. It also declares death to anyone who does not worship the authority of the Sea Beast. Those who are killed for not conforming to the authority of the Sea Beast are blessed through the "first resurrection" that allows them to rule in Christ's presence as priests during the one thousand-year reign. The second death has no power over these individuals who were victorious over the beast by not being deceived, even though they lost their lives on Earth by his authority.
Mark of the Beast
The number of the beast (, ) is associated with the Beast in chapter 13, verse 18 of the Book of Revelation. In most manuscripts of the New Testament and in English translations of the Bible, the number of the beast is "six hundred sixty-six" or (in Greek numerals, represents 600, represents 60 and represents 6). Papyrus 115 (which is the oldest preserved manuscript of the Revelation ), as well as other ancient sources like Codex Ephraemi Rescriptus, give the number of the beast as χιϛ or χιϲ (transliterable in Arabic numerals as "616") (), not 666; critical editions of the Greek text, such as the Novum Testamentum Graece, note as a variant.
In Roman Numerals, in use when the Book of Revelation was written, the mark of the beast in Revelation 17:9 is rendered DCLXVI 'The Roman numeral for 666, DCLXVI, has exactly one occurrence of all symbols whose value is less than 1000 in decreasing order (D = 500, C = 100, L = 50, X = 10, V = 5, I = 1).'
The seven heads of the beast are described in Revelation as representing seven hills.
Rome was built on seven hills.
The mark of the beast is interpreted differently in the four main views of Christian eschatology.
Fate of the False Prophet
Heaven opens and a figure on a white horse appears, followed by "the armies which were in heaven".
The beast and the kings of the earth and their armies gather to prepare for war against them. The beast is taken, along with the false prophet, and they are thrown alive into "the lake of fire" and the rest are killed. In chapter twenty, after the dragon is freed from the abyss and deceives the nations, the dragon is thrown into the lake of fire, where the beast and the false prophet are and will be tormented day and night forever and ever.
Interpretations
Preterism
Preterism is a Christian eschatological view that interprets prophecies of the Bible, especially the Books of Daniel and Revelation, by reference to events that had already happened. Preterist academic scholars generally identify the first beast from the sea with the Roman Empire, particularly with Emperor Nero.
The beast from the earth is generally identified with the Roman imperial cult. Sometimes there is a particular identification with a personage such as a chief administrator of Roman rule in Ephesus and Asia Minor. This is probably the provincial governor (or proconsul) who would have overseen the political and religious operations of the area from his capital in Ephesus or the High Priest of the provincial imperial cult. The imperial cult in Ephesus was set up by Domitian in AD 89. (Ephesus is the location of one of the Seven Churches in Asia to whom the Book of Revelation was addressed.)
This interpretation is based upon the angel's explanation of the beast in , that the beast's seven heads are seven kings () and that Nero, is the sixth king "who is", who was possibly alive and the emperor reigning at the time John was writing the book. The five kings who have fallen are seen as Julius, Augustus, Tiberius, Caligula and Claudius; Galba is the one who "has not yet come, but when he does come, he must remain for a little while". (). Moreover, Rome was known in antiquity as the city of seven hills () and Revelation was a warning about events that were "shortly" to take place (Revelation 1:1).
In , the beast was given a mouth speaking in blasphemies against God and his name. Inscriptions have been found in Ephesus in which Nero is called "Almighty God" and "Savior". In verse 4, the beast is worshiped by the world alongside the dragon that gave it authority. Nero and Caligula "abandoned all reserve" in promoting emperor worship—they were the only two who demanded divine honors while still alive. Nero claimed to be the sun-god Apollo.
speaks of the power given to the beast to make war with the saints. Nero was the first of the imperial authorities to persecute Christianity. Tacitus records the scene in Rome when the persecution of Christians (or Chrestians) broke out: "And their death was aggravated with mockeries, insomuch that, wrapped in the hides of wild beasts, they were torn to pieces by dogs, or fastened to crosses to be set on fire, that when the darkness fell they might be burned to illuminate the night."
Revelation 13:5 says that the beast would continue for 42 months. The Neronic persecution was instituted in AD 64 and lasted until his death in June AD 68, which is three and a half years, or 42 months. Nero was even called the beast. Apollonius of Tyana specifically states that Nero was called a beast:
"In my travels, which have been wider than ever man yet accomplished, I have seen man, many wild beasts of Arabia and India; but this beast, that is commonly called a Tyrant, I know not how many heads it has, nor if it be crooked of claw, and armed with horrible fangs. ...And of wild beasts you cannot say that they were ever known to eat their own mother, but Nero has gorged himself on this diet."
The manner of Nero's death corresponds with the prophecy of : "If anyone is destined for captivity, to captivity he goes; if any one kills with the sword, with the sword he must be killed." According to Tertullian, Nero was the first to assail the Christian sect with the imperial sword. He committed suicide by the sword at age 30.
After Nero's death in AD 68, Rome saw a quick succession of short-lived emperors (Galba, Otho, and Vitellius) and a year of civil wars until Vespasian eventually took control in AD 69. The Roman Empire destabilized so greatly that Tacitus reported: "Many believed the end of the empire was at hand". According to Suetonius, to the surprise of the world, "the empire which for a long time had been unsettled and, as it were, drifting through the usurpation and violent death of three emperors, was at last taken in and given stability by the Flavian family". This may be a reference to the mortal wound on one of the heads of the beast "inflicted by the sword" which was later healed (, ). D. K. Wong (2003) wrote that the "healing of the wound" alludes to the so-called Nero Redivivus legend ("revival of Nero" myth). A rumour said that Nero had just disappeared to Parthia, and would one day reappear.
Finally, the readers of Revelation were told to "calculate the number of the beast, for the number is that of a man; and his number is six hundred and sixty-six" (Rev. 13:18). John did not expect that his readers "who had understanding" to have any difficulty identifying the beast, since they could simply calculate the meaning of this number. "Neron Kaisar" ( the Greek rendering, documented by archaeological finds), transliterated into Hebrew (Nrwn Qsr). When using standard mispar hechrechi encoding of gematria, adding the corresponding values yields 666, as shown:
The variant number 616 found in some manuscripts of the Greek text of Revelation may represent the alternative Hebrew spelling (Nrw Qsr) based on the Latin form "Nero Caesar". The variant probably existed to keep consistent the meaning of Nero as the beast.
Historicism
Historicism is a method of interpretation in Christian eschatology which interprets biblical prophecies as actual historical events and identifies symbolic beings with historical persons or societies in the history of the church. This interpretation was favored by the Protestant reformers such as John Wycliff, John Calvin, and Martin Luther, as well as other prominent figures such as Isaac Newton.
According to this interpretation, the beast and false prophet were most commonly identified with the papacy in its political and religious aspects.
The identification with the papacy is a viewpoint echoed by Seventh-day Adventist writers. According to the Seventh-day Adventist Church, the "image to the beast" represents Protestant churches which will form an alliance with the papacy, and the "mark of the beast" refers to a future universal Sunday law. Adventists have interpreted the number of the beast, 666, as corresponding to a Latin title Vicarius Filii Dei of the pope. The number 666 is calculated by using a form of gematria where only the letters which refer to Latin numerals are counted.
In 1866, Uriah Smith was the first to propose the interpretation to the Seventh-day Adventist Church. In The United States in the Light of Prophecy he wrote,
Adventist scholar J. N. Andrews also adopted this view. Uriah Smith maintained his interpretation in the various editions of Thoughts on Daniel and the Revelation, which was influential in the church.
Jimmy Akin of Catholic Answers and additional Catholic source Our Sunday Visitor, a Catholic newspaper (see Vicarius Filii Dei), disagree with the above argument because, "although Vicarius Filii Dei adds up to 666, [it] is not a title of the pope".
The beast from the earth has also been interpreted as the Islamic prophet Muhammed, according to some medieval Christians, particularly Pope Innocent III; Saracens and Antipopes, according to other medieval Christians, particularly Joachim of Fiore; and the government of the United States of America (this is the view of the Seventh-day Adventist Church). This interpretation was introduced by Adventist pioneer John Nevins Andrews.
Samuele Bacchiocchi, an Adventist scholar, has noted that Seventh-day Adventist teaching is moving away from historicism towards a more symbolic interpretation of the mark of the beast.
The Historicist interpretation has fallen out of favor with modern commentaries on Revelation, partially because it has failed to form a consensus on how the outline of the book of Revelation corresponds with history.
Idealism
Idealism, also known as the allegorical or symbolic approach, is an interpretation of the book of Revelation that sees the imagery of the book as non-literal symbols. This is a common viewpoint of modern Christian scholars such as Gregory Beale in his New International Greek Testament Commentary on the Book of Revelation. Some Idealist interpretations identify none of the book's symbols with particular historical events while some idealists like Beale take a more eclectic approach which see that the book portrays events throughout history while also predicting some future events such as the return of Christ.
In this view, the beast from the sea is interpreted as the state or any human kingdom that is in opposition to God. This would include the Roman Empire but would broadly apply to all empires. Scholars take their cue from the parallels between Revelation 13 and Daniel 7, noting that in Daniel 7:17 that the beasts are revealed as kingdoms. Therefore, given that the beast of Revelation 13 is a composite of the beasts of Daniel, one should similarly interpret this beast as a kingdom, more specifically a composite of all kingdoms. Similarly, in some idealist circles, it is suggested that the beast represents different social injustices, such as exploitation of workers, wealth, the elite, commerce, materialism, and imperialism. Various Christian anarchists, such as Jacques Ellul, have associated the State and political power as the beast.
The Idealist interpretation of the beast from the earth is that it represents religious, cultural and economic powers within society which work to compel people to give their allegiance to the state or governmental powers. This was first expressed in the imperial cult of Rome but finds expression at all times of history. In his commentary, Michael Wilcock says "Religion, indeed is too narrow an identification of the second beast. He is, in modern parlance, the ideology – whether religious, philosophical, or political which 'gives breath to' any human social structure organized independently of God."
The Idealist perspective on the number of the beast rejects gematria, envisioning the number not as a code to be broken, but a symbol to be understood. Because there are so many names that can come to 666 and that most systems require converting names to other languages or adding titles when convenient, there is no consensus. Given that numbers are used figuratively throughout the book of Revelation, idealists interpret this number figuratively as well. The common suggestion is that because seven is a number of completeness and is associated with the divine, that six is incomplete and the three sixes mean completely incomplete. Other scholars focus not on incompleteness but on the beast's ability to imitate perfection, that is, to appear authentic. Since the number six is one short of the perfect number seven, the beast's number bears "most of the hallmarks of truth, and so it can easily deceive".
The Idealist interpretation in which the beast finds expression in the socio-cultural, economic and political arena of all human activities since the existence of man best describes the scriptural perspective of the beast. This position was annunciated by Chike Udolisa is his book. In this perspective, the image of the four kingdoms that were to rule the world as shown to Nebuchadnezzar were equated to the four beasts revealed to Daniel, and to the seven-headed beast revealed to John. The records of and show this beast to represent the kings of the earth. Furthermore, the revelation in Daniel 7 of four beasts comprising a lion, bear and leopard also correlates with the seven-headed beast as shown to John in having the same features of the lion, bear and leopard. Thus the beast represents the kingdoms that will bear rule over the world from Adam until the second coming of Christ. While in the spirit, this beast is seen as a personality as in Revelation 19:20, in the physical he is represented at different ages throughout the period of human existence as different kingdoms. The importance of this interpretation is that as the Whore of Babylon is seen to be riding this beast, the beast is the seat of operation of the whore from where she is expressed, and by whom her dominion is exercised. This corresponds to Revelation 13 where the power exercised by this beast was completely that of the dragon. This brings to light the scriptural fact that the governments of the nations are puppets in the hands of this beast, consistent with the truth that the whole world system is under the dragon, the god of this world.
St. Augustine of Hippo takes a more Idealist interpretation when he writes:
Futurism
Futurism is a Christian eschatological view that interprets portions of the Book of Revelation and the Book of Daniel as future events in a literal, physical, apocalyptic, and global context. This viewpoint is adopted by Dispensationalism and has become deeply rooted in American Evangelical churches.
Futurism interprets the beast from the sea to represent a revived Roman empire that will oppose Christians in the last days. Futurists would admit the symbolic ties to Rome and would interpret that the recovery from the fatal head wound would refer to a revival of this empire in the last days. It is usually understood that this revived empire will be ruled by the Antichrist, though some refer to the beast as the Antichrist. Futurist scholars, such as John Walvoord, identify this beast not as the individual ruler but as the revived Roman empire, noting that the reference to Rome's seven hills and the connection to the beasts in Daniel seven indicate that the beast represents a kingdom.
Futurism interprets the beast from the earth, or false prophet, as the future head of the apostate church or as a future expression of false religion in general.
Interpretation of the mark or number of the beast is similar to the idealist view suggesting that the number six refers to imperfection, falling short of the divine number seven.
Alternative views
The Bahá'í Faith identifies the Beast to be the Umayyad Caliphate, who waged spiritual war against the "two witnesses," understood to be Muhammad, the founder of Islam, and Ali.
Aleister Crowley claimed that he was the Beast prophesied in Revelation and used the name (To Méga Thēríon, sometimes shortened to just Therion), Greek for "The Great Beast", which adds up to 666 by isopsephy, the Greek form of gematria.
During the New Deal, some ministers identified the Congress of Industrial Organizations as a "Sign of the Beast". Outside of black churches, 20th-century evangelicalism in America tended to regard labor unions as the mark of the beast, although evangelicals originally worked to eliminate class distinctions.
Some identify the Beast with a supercomputer in Brussels, Belgium. However, author Joe Musser attributes the origin of this urban legend to his 1970 novel Behold, a Pale Horse and to an ad campaign promoting the movie The Rapture which featured the Brussels-based supercomputer. This ad campaign consisted of make-believe newspapers containing "reports" on various aspects of the movie. Musser speculates that stories subsequently run in an unnamed Pennsylvania newspaper and a 1976 issue of Christian Life magazine were mistakenly based on these ads.
Various Christian anarchists, such as J. Ellul, have identified the State and political power as the beast in the Book of Revelation.
See also
Abomination of desolation
Behemoth, a beast mentioned in the Tanakh (Old Testament)
Dābbat al-Arḍ in Islamic belief
Events of Revelation (Chapter 13)
Lotan, the seven-headed sea serpent or dragon of Ugaritic myths
Mušḫuššu
The horse in Nordic mythology
Notes
External links
Bible-related controversies
Book of Revelation
New Testament words and phrases
Numerology
Seven in the Book of Revelation | The Beast (Revelation) | [
"Mathematics"
] | 5,416 | [
"Numerology",
"Mathematical objects",
"Numbers"
] |
11,708,313 | https://en.wikipedia.org/wiki/Sodium%20nonanoyloxybenzenesulfonate | Sodium nonanoyloxybenzenesulfonate (NOBS) is an important component of laundry detergents and bleaches. It is known as a bleach activator for active oxygen sources, allowing formulas containing hydrogen peroxide releasing chemicals (specifically sodium perborate, sodium percarbonate, sodium perphosphate, sodium persulfate, and urea peroxide) to effect bleaching at lower temperatures.
Synthesis
NOBS is formed by the reaction of nonanoic acid (or its esters) with phenol followed by aromatic sulfonation using SO3 to form a sulfonic acid at the para-position.
Bleach activation
NOBS was developed by Procter & Gamble in 1983 and was first used in American laundry detergents in 1988. NOBS is the main bleach activator used in the U.S.A. and Japan. Compared to TAED, which is the predominant bleach activator used in Europe, NOBS is efficient at much lower temperatures. At 20 °C NOBS is 100 times more soluble than TAED in water.
When attacked by the perhydroxyl anion (from hydrogen peroxide), NOBS forms peroxynonanoic acid (a peroxy acid) and releases the leaving group sodium 4-hydroxybenzene sulfonate, which is an inert by-product.
References
Cleaning product components
Benzenesulfonates
Anionic surfactants
Organic sodium salts
Nonanoate esters | Sodium nonanoyloxybenzenesulfonate | [
"Chemistry",
"Technology"
] | 318 | [
"Organic sodium salts",
"Components",
"Cleaning product components",
"Salts"
] |
11,708,593 | https://en.wikipedia.org/wiki/Interferometric%20microscopy | Interferometric microscopy or imaging interferometric microscopy is the concept of microscopy which
is related to holography, synthetic-aperture imaging, and off-axis-dark-field illumination techniques.
Interferometric microscopy allows enhancement of resolution of optical microscopy due to interferometric (holographic)
registration of several partial images (amplitude and phase) and the numerical combining.
Combining of partial images
In interferometric microscopy, the image of a micro-object is synthesized numerically as a coherent combination
of partial images with registered amplitude and phase.
For registration of partial images, a conventional holographic set-up is used with a reference wave, as is usual in optical holography. Capturing multiple exposures allows the numerical emulation of a large numerical aperture objective from images obtained with an objective lens with smaller-value numerical aperture.
Similar techniques allows scanning and precise detection of small particles.
As the combined image keeps both amplitude and phase information, the interferometric microscopy can be especially efficient for the phase objects, allowing detection of light variations of index of refraction, which cause the phase shift or the light passing through for a small fraction of a radian.
Non-optical waves
Although the Interferometric microscopy has been demonstrated only for optical images (visible light), this technique may find application in high resolution atom optics, or optics of neutral atom beams (see Atomic de Broglie microscope), where the Numerical aperture is usually very limited
.
See also
Digital holographic microscopy
Holography
Numerical aperture
Raman microscope
Diffraction limited
References
Microscopy
Interferometry
Atomic, molecular, and optical physics
Holography | Interferometric microscopy | [
"Physics",
"Chemistry"
] | 329 | [
"Atomic",
"Microscopy",
" molecular",
" and optical physics"
] |
11,708,841 | https://en.wikipedia.org/wiki/Screw%20picket | A screw picket is a metal device which is used to secure objects to the ground. Today, screw pickets are used widely to temporarily "picket" dogs. They are also used to graze animals such as sheep, goats, and horses. Screw pickets are also used to stabilize small trees, tent poles, and other objects that are intended to remain upright.
The original picket was a stake hammered into the ground to secure a horse by tying it to the stake. This required a second tool (a hammer) or the availability of a rock to use instead of a tool. The screw picket is screwed (by turning it) into the ground. In hard ground, it requires a second tool (a leverage bar, or a spare screw picket) or the availability of a length of wood. Screw pickets can be easily bent or broken, but less easily pulled from the ground.
Military non-equestrian use
Screw pickets (used as supports for barbed wire defences) were introduced c. 1915 as a replacement for timber posts. Crown Iron Works Co. (Minneapolis, MN) made over 10 million of these screw post pickets for WW1, WW2 and the Cuban Missile Crisis. The French name for this type of "steel stake" was "queue de cochon" or pigtail. The World War I steel stake became known in the British Army as a "corkscrew picket". The corkscrew picket was made from a steel bar which had its bottom end bent into a spiral coil. It also had three loops or "eyes" (some even had four) formed, one at top, one at midway and one just above the corkscrew spiral. The final product was about eight feet long.
Groups of soldiers known as wiring parties went out at night into no man's land to position these supports. They later strung the barbed wire through the loops to form a defensive wire obstacle as a protection for their trench line. The British called this type of stake a 'corkscrew' picket because it was screwed into the ground rather than hammered in as the timber posts had been (the hammering made loud noise, usually attracting enemy fire). The screw pickets replaced the timber posts (although screw pickets were less rigid than timber posts), because they could be installed rapidly and silently. A wiring party is described in detail in World War I novel All Quiet on the Western Front by contemporary author Erich Maria Remarque.
The corkscrew picket was screwed into the ground by turning it in a clockwise direction using an entrenching tool's handle or a stick inserted in the bottom eye of the picket for leverage. The bottom eye was used in order to avoid bending the vertical bar of the picket.
Notes
See also
Auger (drill)
Materiel
Wire obstacle
Trench warfare
Military equipment of World War I
Fences
Animal equipment | Screw picket | [
"Biology"
] | 577 | [
"Animal equipment",
"Animals"
] |
11,708,890 | https://en.wikipedia.org/wiki/Conditional%20gene%20knockout | Conditional gene knockout is a technique used to eliminate a specific gene in a certain tissue, such as the liver. This technique is useful to study the role of individual genes in living organisms. It differs from traditional gene knockout because it targets specific genes at specific times rather than being deleted from beginning of life. Using the conditional gene knockout technique eliminates many of the side effects from traditional gene knockout. In traditional gene knockout, embryonic death from a gene mutation can occur, and this prevents scientists from studying the gene in adults. Some tissues cannot be studied properly in isolation, so the gene must be inactive in a certain tissue while remaining active in others. With this technology, scientists are able to knockout genes at a specific stage in development and study how the knockout of a gene in one tissue affects the same gene in other tissues.
Technique
The most commonly used technique is the Cre-lox recombination system. The Cre recombinase enzyme specifically recognizes two lox (loci of recombination) sites within DNA and causes recombination between them. During recombination two strands of DNA exchange information. This recombination will cause a deletion or inversion of the genes between the two lox sites, depending on their orientation. An entire gene can be removed to inactivate it. This whole system is inducible so a chemical can be added to knock genes out at a specific time. Two of the most commonly used chemicals are tetracycline, which activates transcription of the Cre recombinase gene and tamoxifen, which activates transport of the Cre recombinase protein to the nucleus. Only a few cell types express Cre recombinase and no mammalian cells express it so there is no risk of accidental activation of lox sites when using conditional gene knockout in mammals. Figuring out how to express Cre-recombinase in an organism tends to be the most difficult part of this technique.
Uses
The conditional gene knockout method is often used to model human diseases in other mammals. It has increased scientists’ ability to study diseases, such as cancer, that develop in specific cell types or developmental stages. It is known that mutations in the BRCA1 gene are linked to breast cancer. Scientists used conditional gene knockout to delete the BRCA1 allele in mammary gland tissue in mice and found that it plays an important role in tumour suppression.
A specific gene in mouse brain thought to be involved in the onset of Alzheimer's disease which codes for the enzyme cyclin-dependent kinase 5 (Cdk5) was knocked out. Such mice were found to be 'smarter' than normal mice and were able to handle complex tasks more intelligently compared to 'normal' mice bred in the laboratory.
Knockout Mouse Project (KOMP)
Conditional gene knockouts in mice are often used to study human diseases because many genes produce similar phenotypes in both species. For the past 100 years laboratory mouse genetics have been used for this because mice are mammals that are physiologically similar enough to humans to generate qualitative testing. These two have such similar genes that out of 4000 studied genes, only 10 were found in one species but not the other. All mammals shared the same common ancestor approximately 80 million years ago; technically speaking, all genomes of mammals are comparatively similar. However, in comparison between mice and humans, their protein-coding regions of the genomes are 85% identical and have similarities between 99% of their homologs. These similarities result in similar phenotypes to be expressed between the two species.[8][12] Their genes are very alike to those of humans with 99% having homologs being similar. Along with producing similar phenotypes as well making them very promising candidates for conditional gene knockouts.[8] The goal of KOMP is to create knockout mutations in the embryonic stem cells for each of the 20,000 protein coding genes in mice. The genes are knocked out because this is the best way to study their function and learn more about their role in human diseases. There are two main strategies to conditional gene knockout and those are gene targeting or homologous recombination and gene trapping. Both methods usually have a modified viral vector or a linear fragment as the mode of transportation of the artificial DNA into the target ES cell. The cells then grow in a petri dish for several days and are inserted into the early-stage embryos. Lastly, the embryos are placed into the adult female's uterus where it can grow into its offspring.[9] Some alleles in this project cannot be knocked out using traditional methods and require the specificity of the conditional gene knockout technique. Other combinatorial methods are needed to knockout the last remaining alleles. Conditional gene knockout is a time-consuming procedure and there are additional projects focusing on knocking out the remaining mouse genes. The KOMP project contributor, Oliver Smithies, arguably provided the biggest scientific impact on this gene targeting. Oliver received the Nobel prize for medicine due to a technique allowing the ability to identify functions in genes and how to use the 'knockout' method to delete certain genes. Unfortunately, the pioneer in gene targeting died at the age of 91 on January 10, 2017.[11] The KOMP projected was started in 2006 and is still ongoing today. The KOMP Repository provides incentives to those partaking in the projects to return feedback to them and those who meet specific criteria can be refunded 50% of the cost of their research cells.[10]
References
8. Austin, C. P., Battey, J. F., Bradley, A., Bucan, M., Capecchi, M., Collins, F. S., Dove, W. F., Duyk, G., Dymecki, S., Eppig, J. T., Grieder, F. B., Heintz, N., Hicks, G., Insel, T. R., Joyner, A., Koller, B. H., Lloyd, K. C., Magnuson, T., Moore, M. W., Nagy, A., ... Zambrowicz, B. (2004). The knockout mouse project. Nature genetics, 36(9), 921–924. https://doi.org/10.1038/ng0904-921
9. Knockout Mice Fact Sheet. (n.d.). Retrieved from https://www.genome.gov/about-genomics/fact-sheets/Knockout-Mice-Fact-Sheet
10. Lloyd K. C. (2011). A knockout mouse resource for the biomedical research community. Annals of the New York Academy of Sciences, 1245, 24–26. https://doi.org/10.1111/j.1749-6632.2011.06311.x
11. Nobel Prize winner Dr. Oliver Smithies to deliver Earl H. Morris Endowed Lecture on July 10. (n.d.). Retrieved from https://medicine.wright.edu/about/article/2009/smithieslecture
12. NIH. (n.d.). Why Mouse Matters. Retrieved from https://www.genome.gov/10001345/importance-of-mouse-genome
Genetic engineering | Conditional gene knockout | [
"Chemistry",
"Engineering",
"Biology"
] | 1,531 | [
"Biological engineering",
"Genetic engineering",
"Molecular biology"
] |
11,709,087 | https://en.wikipedia.org/wiki/Turbine%20engine%20failure | A turbine engine failure occurs when a gas turbine engine unexpectedly stops producing power due to a malfunction other than fuel exhaustion. It often applies for aircraft, but other turbine engines can also fail, such as ground-based turbines used in power plants or combined diesel and gas vessels and vehicles.
Reliability
Turbine engines in use on today's turbine-powered aircraft are very reliable. Engines operate efficiently with regularly scheduled inspections and maintenance. These units can have lives ranging in the tens of thousands of hours of operation. However, engine malfunctions or failures occasionally occur that require an engine to be shut down in flight. Since multi-engine airplanes are designed to fly with one engine inoperative and flight crews are trained to fly with one engine inoperative, the in-flight shutdown of an engine typically does not constitute a serious safety of flight issue.
The Federal Aviation Administration (FAA) was quoted as stating turbine engines have a failure rate of one per 375,000 flight hours, compared to of one every 3,200 flight hours for aircraft piston engines.
Due to "gross under-reporting" of general aviation piston engines in-flight shutdowns (IFSD), the FAA has no reliable data and assessed the rate "between 1 per 1,000 and 1 per 10,000 flight hours".
Continental Motors reports the FAA states general aviation engines experience one failures or IFSD every 10,000 flight hours, and states its Centurion engines is one per flight hours, lowering to one per flight hours in 2013–2014.
The General Electric GE90 has an in-flight shutdown rate (IFSD) of one per million engine flight-hours.
The Pratt & Whitney Canada PT6 is known for its reliability with an in-flight shutdown rate of one per hours from 1963 to 2016, lowering to one per hours over 12 months in 2016.
Emergency landing
Following an engine shutdown, a precautionary landing is usually performed with airport fire and rescue equipment positioned near the runway. The prompt landing is a precaution against the risk that another engine will fail later in the flight or that the engine failure that has already occurred may have caused or been caused by other as-yet unknown damage or malfunction of aircraft systems (such as fire or damage to aircraft flight controls) that may pose a continuing risk to the flight. Once the aircraft lands, fire department personnel assist with inspecting the aircraft to ensure it is safe before it taxis to its parking position.
Rotorcraft
Turboprop-powered aircraft and turboshaft-powered helicopters are also powered by turbine engines and are subject to engine failures for many similar reasons as jet-powered aircraft. In the case of an engine failure in a helicopter, it is often possible for the pilot to enter autorotation, using the unpowered rotor to slow the aircraft's descent and provide a measure of control, usually allowing for a safe emergency landing even without engine power.
Shutdowns that are not engine failures
Most in-flight shutdowns are harmless and likely to go unnoticed by passengers. For example, it may be prudent for the flight crew to shut down an engine and perform a precautionary landing in the event of a low oil pressure or high oil temperature warning in the cockpit. However, passengers in a jet powered aircraft may become quite alarmed by other engine events such as a compressor surge — a malfunction that is typified by loud bangs and even flames from the engine's inlet and tailpipe. A compressor surge is a disruption of the airflow through a gas turbine jet engine that can be caused by engine deterioration, a crosswind over the engine's inlet, ice accumulation around the engine inlet, ingestion of foreign material, or an internal component failure such as a broken blade. While this situation can be alarming, the engine may recover with no damage.
Other events that can happen with jet engines, such as a fuel control fault, can result in excess fuel in the engine's combustor. This additional fuel can result in flames extending from the engine's exhaust pipe. As alarming as this would appear, at no time is the engine itself actually on fire.
Also, the failure of certain components in the engine may result in a release of oil into bleed air that can cause an odor or oily mist in the cabin. This is known as a fume event. The dangers of fume events are the subject of debate in both aviation and medicine.
Possible causes
Engine failures can be caused by mechanical problems in the engine itself, such as damage to portions of the turbine or oil leaks, as well as damage outside the engine such as fuel pump problems or fuel contamination. A turbine engine failure can also be caused by entirely external factors, such as volcanic ash, bird strikes or weather conditions like precipitation or icing. Weather risks such as these can sometimes be countered through the usage of supplementary ignition or anti-icing systems.
Failures during takeoff
A turbine-powered aircraft's takeoff procedure is designed around ensuring that an engine failure will not endanger the flight. This is done by planning the takeoff around three critical V speeds, V1, VR and V2. V1 is the critical engine failure recognition speed, the speed at which a takeoff can be continued with an engine failure, and the speed at which stopping distance is no longer guaranteed in the event of a rejected takeoff. VR is the speed at which the nose is lifted off the runway, a process known as rotation. V2 is the single-engine safety speed, the single engine climb speed. The use of these speeds ensure that either sufficient thrust to continue the takeoff, or sufficient stopping distance to reject it will be available at all times.
Failure during extended operations
In order to allow twin-engined aircraft to fly longer routes that are over an hour from a suitable diversion airport, a set of rules known as ETOPS (Extended Twin-engine Operational Performance Standards) is used to ensure a twin turbine engine powered aircraft is able to safely arrive at a diversionary airport after an engine failure or shutdown, as well as to minimize the risk of a failure. ETOPS includes maintenance requirements, such as frequent and meticulously logged inspections and operation requirements such as flight crew training and ETOPS-specific procedures.
Contained and uncontained failures
Engine failures may be classified as either as "contained" or "uncontained".
A contained engine failure is one in which all internal rotating components remain within or embedded in the engine's case (including any containment wrapping that is part of the engine), or exit the engine through the tail pipe or air inlet.
An uncontained engine event occurs when an engine failure results in fragments of rotating engine parts penetrating and escaping through the engine case.
The very specific technical distinction between a contained and uncontained engine failure derives from regulatory requirements for design, testing, and certification of aircraft engines under Part 33 of the U.S. Federal Aviation Regulations, which has always required turbine aircraft engines to be designed to contain damage resulting from rotor blade failure. Under Part 33, engine manufacturers are required to perform blade off tests to ensure containment of shrapnel if blade separation occurs. Blade fragments exiting the inlet or exhaust can still pose a hazard to the aircraft, and this should be considered by the aircraft designers. A nominally contained engine failure can still result in engine parts departing the aircraft as long as the engine parts exit via the existing openings in the engine inlet or outlet, and do not create new openings in the engine case containment. Fan blade fragments departing via the inlet may also cause airframe parts such as the inlet duct and other parts of the engine nacelle to depart the aircraft due to deformation from the fan blade fragment's residual kinetic energy.
The containment of failed rotating parts is a complex process which involves high energy, high speed interactions of numerous locally and remotely located engine components (e.g., failed blade, other blades, containment structure, adjacent cases, bearings, bearing supports, shafts, vanes, and externally mounted components). Once the failure event starts, secondary events of a random nature may occur whose course and ultimate conclusion cannot be precisely predicted. Some of the structural interactions that have been observed to affect containment are the deformation and/or deflection of blades, cases, rotor, frame, inlet, casing rub strips, and the containment structure.
Uncontained turbine engine disk failures within an aircraft engine present a direct hazard to an airplane and its crew and passengers because high-energy disk fragments can penetrate the cabin or fuel tanks, damage flight control surfaces, or sever flammable fluid or hydraulic lines. Engine cases are not designed to contain failed turbine disks. Instead, the risk of uncontained disk failure is mitigated by designating disks as safety-critical parts, defined as the parts of an engine whose failure is likely to present a direct hazard to the aircraft.
Notable uncontained engine failure accidents
National Airlines Flight 27: a McDonnell Douglas DC-10 flying from Miami to San Francisco in 1973 had an overspeed failure of a General Electric CF6-6, resulting in one fatality.
Two LOT Polish Airlines flights, both Ilyushin Il-62s, suffered catastrophic uncontained engine failures in the 1980s. The first was in 1980 on LOT Polish Airlines Flight 7 where flight controls were destroyed, killing all 87 on board. In 1987, on LOT Polish Airlines Flight 5055, the failure of the aircraft's inner left (#2) engine damaged the outer left (#1) engine, setting both on fire and causing loss of flight controls, leading to a crash that killed all 183 people on board. In both cases, the turbine shaft in engine #2 disintegrated due to production defects in the engines' bearings, which were missing rollers.
The Tu-154 crash near Krasnoyarsk was a major aircraft crash that occurred on Sunday, December 23, 1984, in the vicinity of Krasnoyarsk. The Tu-154B-2 airliner of the 1st Krasnoyarsk united aviation unit (Aeroflot) performed passenger flight SU-3519 on the Krasnoyarsk-Irkutsk route, but during the climb, engine No. 3 failed. The crew decided to return to the airport of departure, but during the landing approach a fire broke out, which destroyed the control systems and as a result, the plane crashed to the ground 3200 meters from the threshold of the runway of the Yemelyanovo airport and collapsed. Of the 111 people on board (104 passengers and 7 crew members), one survived. The cause of the catastrophe was the destruction of the disk of the first stage of the low pressure circuit of engine No. 3, which occurred due to the presence of fatigue cracks. The cracks were caused by a manufacturing defect – the inclusion of a titanium-nitrogen compound that has a higher microhardness than the original material. The methods used at that time for the manufacture and repair of disks, as well as the means of control, were found to be partially obsolete, which is why they did not ensure the effectiveness of control and detection of such a defect. The defect itself arose probably due to accidental ingestion of a titanium sponge or charge for smelting an ingot of a piece enriched with nitrogen.
Cameroon Airlines Flight 786: a Boeing 737 flying between Douala and Garoua, Cameroon in 1984 had a failure of a Pratt & Whitney JT8D-15 engine. Two people died.
British Airtours Flight 28M: a Boeing 737 flying from Manchester to Corfu in 1985 suffered an uncontained engine failure and fire on takeoff. The takeoff was aborted and the plane turned onto a taxiway and began evacuating. Fifty-five passengers and crew were unable to escape and died of smoke inhalation. The accident led to major changes to improve the survivability of aircraft evacuations.
United Airlines Flight 232: a McDonnell Douglas DC-10 flying from Denver to Chicago in 1989. The failure of the rear General Electric CF6-6 engine caused the loss of all hydraulics, forcing the pilots to attempt a landing using differential thrust. There were 111 fatalities. Prior to this crash, the probability of a simultaneous failure of all three hydraulic systems was considered as low as one in a billion. However, statistical models did not account for the position of the number-two engine, mounted at the tail close to hydraulic lines, nor the results of fragments released in many directions. Since then, aircraft engine designs have focused on keeping shrapnel from puncturing the cowling or ductwork, increasingly utilizing high-strength composite materials to achieve penetration resistance while keeping the weight low.
Baikal Airlines Flight 130: a starter of engine No. 2 on a Tu-154 heading from Irkutsk to Domodedovo, Moscow in 1994, failed to stop after engine startup and continued to operate at over 40,000 rpm with open bleed valves from engines, which caused an uncontained failure of the starter. A detached turbine disk damaged fuel and oil supply lines (which caused fire) and hydraulic lines. The fire-extinguishing system failed to stop the fire, and the plane diverted back to Irkutsk. However, due to loss of hydraulic pressure the crew lost control of the plane, which subsequently crashed into a dairy farm killing all 124 on board and one on the ground.
ValuJet 597: A DC-9-32 taking off from Hartsfield Jackson Atlanta International Airport on June 8, 1995, suffered an uncontained engine failure of the 7th stage high pressure compressor disk due to inadequate inspection of the corroded disk. The resulting rupture caused jet fuel to flow into the cabin and ignite, and the fire caused the jet to be a write-off.
Delta Air Lines Flight 1288: a McDonnell Douglas MD-88 flying from Pensacola, Florida to Atlanta in 1996 had a cracked compressor rotor hub failure on one of its Pratt & Whitney JT8D-219 engines. Two died.
TAM Flight 9755: a Fokker 100, departing Recife/Guararapes–Gilberto Freyre International Airport for São Paulo/Guarulhos International Airport on 15 September 2001, suffered an uncontained engine failure (Rolls-Royce RB.183 Tay) in which fragments of the engine shattered three cabin windows, causing decompression and pulling a passenger partly out of the plane. Another passenger held the passenger in until the aircraft landed, but the passenger blown out of the window died.
Qantas Flight 32: an Airbus A380 flying from London Heathrow to Sydney (via Singapore) in 2010 had an uncontained failure in a Rolls-Royce Trent 900 engine. The failure was found to have been caused by a misaligned counter bore within a stub oil pipe leading to a fatigue fracture. This in turn led to an oil leakage followed by an oil fire in the engine. The fire led to the release of the Intermediate Pressure Turbine (IPT) disc. The airplane, however, landed safely. This led to the grounding of the entire Qantas A380 fleet.
British Airways Flight 2276: a Boeing 777-200ER flying from Las Vegas to London in 2015 suffered an uncontained engine failure on its #1 GE90 engine during takeoff, resulting in a large fire on its port side. The aircraft successfully aborted takeoff and the plane was evacuated with no fatalities.
American Airlines Flight 383: a Boeing 767-300ER flying from Chicago to Miami in 2016 suffered an uncontained engine failure on its #2 engine (General Electric CF6) during takeoff resulting in a large fire which destroyed the outer right wing. The aircraft aborted takeoff and was evacuated with 21 minor injuries, but no fatalities.
Air France Flight 66: an Airbus A380, registration F-HPJE performing flight from Paris, France, to Los Angeles, United States, was en route about southeast of Nuuk, Greenland, when it suffered a catastrophic engine failure in 2017 (General Electric / Pratt & Whitney Engine Alliance GP7000). The crew descended the aircraft and diverted to Goose Bay, Canada, for a safe landing about two hours later.
References
This article contains text from a publication of the United States National Transportation Safety Board. which can be found here As a work of the United States Federal Government, the source is in the public domain and may be adapted freely per USC Title 17; Chapter 1; §105 (see Wikipedia:Public Domain).
Turbines
Jet engines
Aviation safety
Aviation risks
Emergency aircraft operations
Aircraft engines | Turbine engine failure | [
"Chemistry",
"Technology"
] | 3,379 | [
"Engines",
"Turbomachinery",
"Turbines",
"Jet engines",
"Aircraft engines"
] |
11,709,182 | https://en.wikipedia.org/wiki/Radiosity%20%28radiometry%29 | In radiometry, radiosity is the radiant flux leaving (emitted, reflected and transmitted by) a surface per unit area, and spectral radiosity is the radiosity of a surface per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength. The SI unit of radiosity is the watt per square metre (), while that of spectral radiosity in frequency is the watt per square metre per hertz (W·m−2·Hz−1) and that of spectral radiosity in wavelength is the watt per square metre per metre (W·m−3)—commonly the watt per square metre per nanometre (). The CGS unit erg per square centimeter per second () is often used in astronomy. Radiosity is often called in branches of physics other than radiometry, but in radiometry this usage leads to confusion with radiant intensity.
Mathematical definitions
Radiosity
Radiosity of a surface, denoted Je ("e" for "energetic", to avoid confusion with photometric quantities), is defined as
where
∂ is the partial derivative symbol
is the radiant flux leaving (emitted, reflected and transmitted)
is the area
is the emitted component of the radiosity of the surface, that is to say its exitance
is the reflected component of the radiosity of the surface
is the transmitted component of the radiosity of the surface
For an opaque surface, the transmitted component of radiosity Je,tr vanishes and only two components remain:
In heat transfer, combining these two factors into one radiosity term helps in determining the net energy exchange between multiple surfaces.
Spectral radiosity
Spectral radiosity in frequency of a surface, denoted Je,ν, is defined as
where ν is the frequency.
Spectral radiosity in wavelength of a surface, denoted Je,λ, is defined as
where λ is the wavelength.
Radiosity method
The radiosity of an opaque, gray and diffuse surface is given by
where
ε is the emissivity of that surface;
σ is the Stefan–Boltzmann constant;
T is the temperature of that surface;
Ee is the irradiance of that surface.
Normally, Ee is the unknown variable and will depend on the surrounding surfaces. So, if some surface i is being hit by radiation from some other surface j, then the radiation energy incident on surface i is Ee,ji Ai = Fji Aj Je,j where Fji is the view factor or shape factor, from surface j to surface i. So, the irradiance of surface i is the sum of radiation energy from all other surfaces per unit surface of area Ai:
Now, employing the reciprocity relation for view factors Fji Aj = Fij Ai,
and substituting the irradiance into the equation for radiosity, produces
For an N surface enclosure, this summation for each surface will generate N linear equations with N unknown radiosities, and N unknown temperatures. For an enclosure with only a few surfaces, this can be done by hand. But, for a room with many surfaces, linear algebra and a computer are necessary.
Once the radiosities have been calculated, the net heat transfer at a surface can be determined by finding the difference between the incoming and outgoing energy:
Using the equation for radiosity Je,i = εiσTi4 + (1 − εi)Ee,i, the irradiance can be eliminated from the above to obtain
where Me,i° is the radiant exitance of a black body.
Circuit analogy
For an enclosure consisting of only a few surfaces, it is often easier to represent the system with an analogous circuit rather than solve the set of linear radiosity equations. To do this, the heat transfer at each surface is expressed as
where Ri = (1 − εi)/(Aiεi) is the resistance of the surface.
Likewise, Me,i° − Je,i is the blackbody exitance minus the radiosity and serves as the 'potential difference'. These quantities are formulated to resemble those from an electrical circuit V = IR.
Now performing a similar analysis for the heat transfer from surface i to surface j,
where Rij = 1/(Ai Fij).
Because the above is between surfaces, Rij is the resistance of the space between the surfaces and Je,i − Je,j serves as the potential difference.
Combining the surface elements and space elements, a circuit is formed. The heat transfer is found by using the appropriate potential difference and equivalent resistances, similar to the process used in analyzing electrical circuits.
Other methods
In the radiosity method and circuit analogy, several assumptions were made to simplify the model. The most significant is that the surface is a diffuse emitter. In such a case, the radiosity does not depend on the angle of incidence of reflecting radiation and this information is lost on a diffuse surface. In reality, however, the radiosity will have a specular component from the reflected radiation. So, the heat transfer between two surfaces relies on both the view factor and the angle of reflected radiation.
It was also assumed that the surface is a gray body, that is to say its emissivity is independent of radiation frequency or wavelength. However, if the range of radiation spectrum is large, this will not be the case. In such an application, the radiosity must be calculated spectrally and then integrated over the range of radiation spectrum.
Yet another assumption is that the surface is isothermal. If it is not, then the radiosity will vary as a function of position along the surface. However, this problem is solved by simply subdividing the surface into smaller elements until the desired accuracy is obtained.
SI radiometry units
See also
Irradiance
Radiant flux
Spectral flux density
References
Physical quantities
Radiometry | Radiosity (radiometry) | [
"Physics",
"Mathematics",
"Engineering"
] | 1,165 | [
"Physical phenomena",
"Telecommunications engineering",
"Physical quantities",
"Quantity",
"Physical properties",
"Radiometry"
] |
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