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Olivetti P6066 was a personal computer programmable with a version of Basic owned by Olivetti and integrated in the operating system.
It was identical to Olivetti P6060 in the mechanical design; however, the color (white) and performances were different.
It was an improved version of the P6060, from which it was possible to make an upgrade.
Head of the development was Pier Giorgio Perotto , and the production site was Scarmagno .
This computing article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Olivetti_P6066 |
An Olivier pile is a drilled displacement pile:. [ 1 ] This is an underground deep foundation pile made of concrete or reinforced concrete with a screw-shaped shaft ( helical shaft ) which is performed without soil removal.
The Belgian Gerdi Vankeirsbilck applied for the production patent for the Olivier pile in April 1996. [ 2 ] This technique was implemented by his own company and various licences have been granted in Belgium and abroad. Due to its screw-shaped shaft, the Olivier pile is particularly suitable for use in soils with low load-bearing capacities, such as clay and loam . [ 3 ] In 2018 a patent was applied for drilling without the use of a lost bit. [ 4 ]
An Olivier pile is drilled into the ground by the use of drilling rig with a top-type rotary drive with variable rate of penetration. A lost tip is attached to a partial-flight auger which, in turn, is attached to a casing . The casing, which is rotated clockwise continuously, penetrates into the ground by the action of a torque and a vertical force. At the desired installation depth, the lost tip is released, and the reinforcing cage is inserted into the casing. Concrete is then placed inside the casing through a funnel . The casing and the partialflight auger are extracted by counter-clockwise rotation. The shaft of the Olivier pile has the shape of a screw. [ 5 ] [ 6 ]
The casing has an external diameter of 324mm (12.75"), with a wall thickness of 25mm (1"). The casing consists of several parts assembled with watertight couplings, which are strong enough to handle the maximum torque produced by the rotary drive. The various auger heads, for the various diameters of the Olivier Pile, all have a larger diameter than the casing.
Common diameters of the auger head [ 7 ] | https://en.wikipedia.org/wiki/Olivier_pile |
Olney's lesions , also known as NMDA receptor antagonist neurotoxicity ( NAT ), is a form of brain damage consisting of selective death of neurons but not glia , observed in restricted brain regions of rats and certain other animal models exposed to large quantities of psychoactive drugs that inhibit the normal operation of the neuronal NMDA receptor . NMDA antagonism is common in anesthesia , as well as certain psychiatric treatments.
The visible signs of NAT are named after John Olney , who conducted a study in 1989 to investigate neurotoxicity caused by PCP and related drugs. It is unclear whether the phenomenon is relevant to the practice of modern medicine : most NMDA antagonists are co-administered with other drugs that reduce neurotoxicity, and the phenomenon is only rarely observed in human subjects who abuse the drugs.
NMDA receptor antagonists include physician-prescribed drugs for therapeutic treatment of human diseases such as memantine for Alzheimer's disease .
In anesthesiology, many general anesthetics generate their dissociative effect through NMDA receptor antagonism. These anesthetics are typically administered with positive allosteric GABA A -receptor modulators to prevent any neurotoxicity they might cause. [ 1 ] Drugs that work to suppress NAT include anticholinergics , [ 2 ] benzodiazepines , barbiturates [ 3 ] and Alpha-adrenergic agonists , such as clonidine . Conversely, coadministration of NMDA-antagonists with α-2 adrenergic antagonists , like yohimbine , could theoretically potentiate NAT.
In the late 1980s, John Olney , a researcher specializing in excitotoxicity , the phenomenon where persistently high neurotransmitter concentrations damage nerve cells , began to investigate the pharmacology of NMDA receptor antagonists . Other workers had recently begun proposing to use NMDA antagonists PCP , MK-801 (dizocilpine) and ketamine in clinical trials for various psychological effects; but the drugs' current illegality meant that scientists had no record of pharmacological response to guide safe use. Olney and his coworkers discovered that, when they injected rats with PCP, dizocilpine, ketamine, or the addition NMDA antagonist tiletamine , the rat brains rapidly developed cell-level vacuolation , a sign of biochemical stress. Within two hours, mitochondria had begun to lyse , and other cytotoxic changes were apparent, peaking at 12 hours following administration. If cells were to recover, they did so within 24 hours, but unrecovered cells went on to neuronal cell death in dissected animals.
The regions of the brain that show neuronal death are remarkably restricted, and consist chiefly of the cingulate and retrosplenial cortex. [ 4 ]
Varying the dosing regimes revealed that the drugs' lesiary potency correlated with their NMDA antagonism (MK-801 > PCP > tiletamine > ketamine). Repeated administration had the same effect as single administration, leading to the conclusion that either the drugs were not cumulatively neurotoxic or that neurotoxicity had already proceeded irreversibly after a single administration. [ 5 ]
Researcher Roland N. Auer conducted similar studies to look at the correlation between age and sex and the development of NMDA receptor antagonist neurotoxicity in test rats. Older rats experienced a much higher mortality rate after the development of NAT, and female rats were found, at all ages, to have a higher incidence of necrotic (dead) neurons as a result of NAT. [ 6 ]
Dextromethorphan , a common antitussive often found in cough medicines , has been shown to cause vacuolization in rats' brains when administered at doses of 75 mg/(kg ip). [ 7 ] However, oral administration of dextromethorphan hydrobromide (DXM HBr) to female rats in single doses as high as 120 mg/kg did not result in detectable neurotoxic changes at 4–6 hours or 24–26 hours post-dose (female rats are more sensitive to NMDA antagonist neurotoxicity). [ 8 ] The same researchers also found no evidence of neurotoxic changes in retrosplenial or cingulate cortices of male rats orally administered up to 400 mg/(kg day) DXM HBr or female rats orally administered 120 mg/(kg day) DXM HBr, both for 30 days. Carliss et al. (2007) also found that rats administered 9 mg/(kg day sc) (+)-MK-801 hydrogen maleate for 30 days did produce detectable vacuolation as expected. When 30 mg/(kg ip) dextrorphan was administered to male rats, neurotoxic changes were observed only 30 minutes post-dose. [ 9 ]
Nitrous oxide , a common anesthetic for humans (especially in dentistry ), has also been shown to cause vacuolization in rats' brains, but caused no irreversible lesions. [ 10 ]
In 1999, an autopsy study by Johannes Kornhuber of 8 patients who had received amantadine therapy looked at the selectively vulnerable brain regions where Olney's lesions occur, the cingulate and retrosplenial cortex, and found no evidence of Olney's lesions. [ 11 ] [ 12 ]
In Ketamine: Dreams and Realities , Karl Jansen writes:
Roland Auer injected the common squirrel monkey with Dizocilpine , or MK-801 and was unable to produce any vacuoles. [ 13 ]
The brain regions where Olney's lesions occur show hypermetabolism [ 14 ] [R]ats have rates of brain metabolism that are almost twice as high as those in humans to start with. [ 15 ] It is because of this higher basal rate of cerebral metabolism that lesions may appear in rodents but not in large and mature primate brains. Ketamine causes over-excitement and euphoria in rats at doses below those at which it activates shutdown systems.
Frank Sharp also works in this area. I discussed with Sharp how this issue stood in 1998. His view was that reversible toxic changes in the rat started to appear at 40mg/kg and reached a level at which no further changes occurred (a plateau) at 100mg/kg, when a little cell death could be seen - but matters would not progress beyond this point. Extensive attempts to produce toxic changes in monkeys had been a total failure at doses up to 10mg/kg i.m. These Gorilla studies are unpublished.
I sought the view of Olney's colleague, Dr Nuri Farber. The work of his team indicated that N-P receptors must be blocked for at least 2 hours to cause reversible changes, and at least 24 hours to produce some cell death, in rats.
[...][H]e thought that the methods used in monkey studies so far were unsatisfactory, because the animals were probably too young. Only adult rats show the toxic changes. He was not prepared to accept a clean bill of health for the drug in primates until this work with elderly Gorillas had been done, and until the drug companies published their Gorilla studies to support their claims of harmlessness.
There is thus no published evidence at this time (January 2000) that ketamine can produce toxic cell changes in monkeys. The unpublished monkey data that we know about, that of Frank Sharp, actually shows that there is no damage at doses up to 10mg/kg.
In 2013 a study using magnetic resonance imaging showed brain lesions in ketamine addicts (using from 0.2g twice a week up to 1g daily for 0.5 up to 12 years) with severity depending on the duration of addiction and daily intake of ketamine. Cortical atrophy and holes in superficial white matter are seen early on. After 4 years of addiction lesions spread throughout the brain and damage is evident in the pons and other deeper brain structures. [ 17 ] | https://en.wikipedia.org/wiki/Olney's_lesions |
Olry Terquem (16 June 1782 – 6 May 1862) was a French mathematician . He is known for his works in geometry and for founding two scientific journals , one of which was the first journal about the history of mathematics . He was also the pseudonymous author (as Tsarphati ) of a sequence of letters advocating radical reform in Judaism. [ 1 ] He was French Jewish .
Terquem grew up speaking Yiddish , and studying only the Hebrew language and the Talmud . [ 2 ] However, after the French Revolution his family came into contact with a wider society, and his studies broadened. [ 2 ] Despite his poor French he was admitted to study mathematics at the École Polytechnique in Paris, beginning in 1801, as only the second Jew to study there. [ 1 ] [ 2 ] [ 3 ] He became an assistant there in 1803, and earned his doctorate in 1804.
After finishing his studies he moved to Mainz (at that time known as Mayence and part of imperial France), where he taught at the Imperial Lycée. In 1811 he moved to the artillery school in the same city, in 1814 he moved again to the artillery school in Grenoble , and in 1815 he became the librarian of the Dépôt Central de l'Artillerie in Paris, where he remained for the rest of his life. He became an officer of the Legion of Honor in 1852. After he died, his funeral was officiated by Lazare Isidor , the Chief Rabbi of Paris and later of France, and attended by over 12 generals headed by Edmond Le Bœuf . [ 1 ] [ 2 ]
Terquem translated works concerning artillery , was the author of several textbooks, and became an expert on the history of mathematics. [ 2 ] Terquem and Camille-Christophe Gerono were the founding editors of the Nouvelles Annales de Mathématiques in 1842. [ 1 ] Terquem also founded another journal in 1855, the Bulletin de Bibliographie, d'Histoire et de Biographie de Mathématiques , which was published as a supplement to the Nouvelles Annales , and he continued editing it until 1861. [ 1 ] [ 4 ] This was the first journal dedicated to the history of mathematics. [ 4 ]
In geometry , Terquem is known for naming the nine-point circle and fully proving its properties. This is a circle that passes through nine special points of any given triangle. Karl Wilhelm Feuerbach had previously observed that the three feet of the altitudes of a triangle and the three midpoints of its sides all lie on a single circle, but Terquem was the first to prove that this circle also contains the midpoints of the line segments connecting each vertex to the orthocenter of the triangle. [ 5 ] He also gave a new proof of Feuerbach's theorem that the nine-point circle is tangent to the incircle and excircles of a triangle . [ 3 ]
Terquem's other contributions to mathematics include naming the pedal curve of another curve, [ 3 ] and counting the number of perpendicular lines from a point to an algebraic curve as a function of the degree of the curve. [ 2 ] He was also the first to observe that the minimum or maximum value of a symmetric function is often obtained by setting all variables equal to each other. [ 2 ]
Terquem has been called the first, most radical, and most outspoken of the major proponents of Jewish reform in France, [ 6 ] [ 7 ] "the enfant terrible of French Judaism". [ 6 ] He published 27 "letters of an Israelite" under the name " Tsarphati " (a Hebrew word for a Frenchman), [ 7 ] [ 8 ] pushing for reforms that in his view would better assimilate Jews into modern life [ 7 ] and better accommodate working-class Jews. [ 6 ] The first nine of these appeared in L'Israélite Français , and the remaining 18 as letters to the editor in Courrier de la Moselle . [ 9 ] Terquem rejected the Talmud , [ 8 ] [ 10 ] proposed to codify intermarriage between Jews and non-Jews, [ 8 ] pushed to move the sabbath to Sunday, [ 6 ] [ 10 ] advocated using other languages than Hebrew for prayers, [ 2 ] and fought against circumcision , [ 7 ] regressive attitudes towards women, [ 6 ] and the Jewish calendar . [ 6 ] However, he had little effect on the Jewish practices of the time. [ 7 ] [ 10 ]
Despite Terquem's calls for reform, and despite having married a Catholic woman and raised his children as Catholic, [ 6 ] he requested that his funeral be held with all the proper Jewish rites. [ 1 ] | https://en.wikipedia.org/wiki/Olry_Terquem |
The Olsen cycle is a pyroelectric cycle, which was developed between 1978 and 1986 by Olsen and Bruno, [ 1 ] by Olsen and Brown, [ 2 ] Olsen and Evans, [ 3 ] as well as by Olsen et al. [ 4 ] It has been called the Ericsson cycle . However, the Olsen cycle avoids the least confusion with its analogous process of the Ericsson cycle. [ 5 ] The Olsen cycle can generate electricity directly from heat when applied to a pyroelectric material, [ 6 ] and has been the most favorable method for the generation of electricity from heat using pyroelectric energy harvesting . [ 7 ] It consists of two isothermal and two isoelectric field processes in the displacement versus electric field diagram. [ 8 ]
It can be compared to the Ericsson cycle, where working fluid undergoes two isothermal and two isobaric processes in a pressure-volume diagram . [ 9 ] [ 10 ] However, the Ericsson cycle does not include the hysteresis loop , which is essentially a lag between the input of an electric field and the material's output. | https://en.wikipedia.org/wiki/Olsen_cycle |
An Olszewski tube is a pipe designed to bring oxygen-poor water from the bottom of a lake to the top. This tube was first proposed by a Polish limnologist named Przemysław Olszewski in 1961 and helps combat the negative effects of eutrophication , high nutrient content, in lakes. The basic concept behind the Olszewski tube is the reduction of nutrient concentration and destratification ; the more specific goal is hypolimnetic withdrawal . [ 1 ]
When nutrients build up in a lake, eutrophication occurs, and this generally occurs in the top layer of a lake. The nutrients come both naturally and artificially and usually contain phosphates . The artificial nutrients can come from sewage and fertilizers, from agricultural runoff . Phosphorus from the phosphates causes algae to grow rapidly and spread throughout the top layer of the lake. Algal blooms have negative effects on both the aesthetics and the ecology of the lake. Aesthetically, the lake is not pleasing because it is covered with algae. Ecologically, eutrophication causes organisms in the lake to die because the algae deplete the dissolved oxygen in the lake. [ 2 ]
At the most simple level, the Olszewski tube is a pipe that spans from the bottom, hypolimnetic layer of the lake to the outlet. The outlet part of the pipe is installed under lake level in order for the device to act as a siphon . Once warm water flows in the lake at the surface, it forces the cold anoxic water of the hypolimnetic layer through and up the tube. This oxygen-poor water is then brought to the top of the lake where the eutrophication occurs. This eventually helps the lake as a whole because the bottom of the lake will have more dissolved oxygen and the top of the lake will have less eutrophication. [ 3 ]
The first implementation of the Olszewski tube was attempted at Lake Kortowo in Poland and this led to oligotrophication , reduction of nutrient cycling . This tube has shown the most promise in a 3.9 meter deep eutrophic lake in Switzerland because the phosphorus and nitrogen levels in the summer drastically decreased, oxygen levels increased, and the amount of cyanobacteria decreased from 152 grams per square meter to 41 grams per square meter. It has also been reported by a scientist named Bjork that there have been successes with the Olszewski tube in European lakes. Other limnologists like Pechlaner and Gachter have reported successes in small lakes where the total phosphorus decreased, transparency of water increased, and less algae was present. [ 4 ] [ 5 ]
Some complications that can arise with the use of an Olszewski tube include disruption of the thermocline and excessive water loss. The thermocline separates the upper layer of water that is mixed temperatures with the deeper, cooler water. If the thermocline is disrupted, it could alter the ecology of the lake, potentially making it uninhabitable. Another complication is that the installation must be a long-term process. Short-term uses of Olszewski tubes have largely failed because it takes some time for the anoxic condition of the hypolimnetic layer to increase in dissolved oxygen. Also, it must be a slow process in order to avoid disrupting the thermocline in a lake. If the Olszewski tube is operated slowly enough, the rate of water going in and going out will be fairly constant causing the thermocline to stay intact. [ 1 ]
One advantage to hypolimnetic withdrawal is that it is relatively inexpensive to install an Olszewski tube or any similar device. Along with low initial cost, it also has a relatively low annual maintenance cost. The following are four systems installed in the United States (2002), their area in hectares , the rate of flow in cube-meters per minute, and their initial installation costs in US dollars: [ 2 ]
41 ha 3.4 m 3 /min $420,000
287 ha 6.3 m 3 /min $62,000
151 ha 9.1 m 3 /min $310,000
412 ha 5.3 m 3 /min $282,000
Aside from using an Olszewski tube and hypolimnetic withdrawal, there are other techniques implemented to achieve the same goals as an Olszewski tube. These include increasing dissolved oxygen, reducing nutrient concentration, and lessening the amount of algae and unwanted biomass in lakes. | https://en.wikipedia.org/wiki/Olszewski_tube |
Olympiadane is a mechanically interlocked molecule composed of five interlocking macrocycles that resembles the Olympic rings . The molecule is a linear pentacatenane or a [5] catenane . It was synthesized and named by Fraser Stoddart and coworkers in 1994. [ 1 ] The molecule was designed without any practical use in mind, [ 2 ] although other catenanes may have possible application to the construction of a molecular computer .
This article about a heterocyclic compound is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Olympiadane |
Olympus Master is a software application that is used with Olympus digital cameras and optical accessories. It can be installed and used on PCs running Windows 2000 , Windows XP or (in the case of the Olympus Master 2 software) Windows Vista , and also on Macintosh computers.
Olympus Master allows users to transfer, browse, print, share and backup images they have taken with their Olympus camera, or other pictures found on the computer. Images are downloaded from the camera via a USB cable or by using a card reader, and are then put into a gallery. From there, images can be selected and transferred to a CD or a file to be stored on the computer. It is useful for converting Olympus digital (ORF) files, which many software packages cannot open. Images can also be edited using the program. Rotate, crop and red-eye are some common functions in the editing menu. Images can also be printed directly from the software if the user has a photo printer connected to their computer.
The Olympus Master software provides the ability to upgrade the firmware of the users Olympus digital camera when it is linked to the computer via the USB cable. Olympus compact digital cameras, Olympus digital SLRs (E-System cameras), Olympus Zuiko Digital lenses and Olympus flash units are supported. This method is the only way of updating firmware within Olympus equipment. Many other manufacturers such as Nikon and Canon use a different method, which allows the user to temporarily save a patch file to a memory card . Once the user has placed the memory card into the camera they wish to update, the camera will install the new firmware directly from the memory card. Both methods have their advantages, as well as their disadvantages.
Olympus Master 2, which is an update to the original version, is available free from Olympus via their website. It is included with Olympus cameras since mid-2007, replacing the original version. Since February 2008, the original version of the software has not been able to detect newer digital cameras (such as the E-420 digital SLR). If users of the older version who purchase a new product wish to continue using Olympus software or wish to update the firmware within their new equipment, they must first update from the original Olympus Master to the newer version.
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Olympus_Master |
Ghiyāth al-Dīn Abū al-Fatḥ ʿUmar ibn Ibrāhīm Nīshābūrī [ 1 ] [ 3 ] (18 May 1048 – 4 December 1131) ( Persian : غیاث الدین ابوالفتح عمر بن ابراهیم خیام نیشابورﻯ), commonly known as Omar Khayyam ( Persian : عمر خیّام ), [ a ] was a Persian poet and polymath, known for his contributions to mathematics , astronomy , philosophy , and Persian literature . [ 4 ] : 94 He was born in Nishapur , Iran and lived during the Seljuk era , around the time of the First Crusade .
As a mathematician, he is most notable for his work on the classification and solution of cubic equations , where he provided a geometric formulation based on the intersection of conics . [ 5 ] He also contributed to a deeper understanding of Euclid 's parallel axiom . [ 6 ] : 284 As an astronomer, he calculated the duration of the solar year with remarkable precision and accuracy, and designed the Jalali calendar , a solar calendar with a very precise 33-year intercalation cycle [ 7 ] : 659 [ b ] which provided the basis for the Persian calendar that is still in use after nearly a millennium.
There is a tradition of attributing poetry to Omar Khayyam, written in the form of quatrains ( rubāʿiyāt رباعیات ). This poetry became widely known to the English-reading world in a translation by Edward FitzGerald ( Rubaiyat of Omar Khayyam , 1859), which enjoyed great success in the Orientalism of the fin de siècle .
Omar Khayyam was born in Nishapur —a metropolis in Khorasan province, of Persian stock, in 1048. [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] In medieval Persian texts he is usually simply called Omar Khayyam . [ 7 ] : 658 [ c ] Although open to doubt, it has often been assumed that his forebears followed the trade of tent-making, since Khayyam means 'tent-maker' in Arabic. [ 15 ] : 30 The historian Bayhaqi , who was personally acquainted with Khayyam, provides the full details of his horoscope: "he was Gemini, the sun and Mercury being in the ascendant[...]". [ 16 ] : 471 [ 17 ] : 172–175, no. 66 This was used by modern scholars to establish his date of birth as 18 May 1048. [ 7 ] : 658
Khayyam's boyhood was spent in Nishapur, [ 7 ] : 659 a leading metropolis in the Seljuk Empire , [ 18 ] : 15 [ 19 ] which had earlier been a major center of the Zoroastrian religion . [ 8 ] : 68 His full name, as it appears in Arabic sources, was Abu’l Fath Omar ibn Ibrahim al-Khayyam . [ d ] His gifts were recognized by his early tutors who sent him to study under Imam Muwaffaq Nishaburi, the greatest teacher of the Khorasan region who tutored the children of the highest nobility, and Khayyam developed a firm friendship with him through the years. [ 8 ] : 20 Khayyam might have met and studied with Bahmanyar , a disciple of Avicenna . [ 8 ] : 20–21 After studying science, philosophy, mathematics and astronomy at Nishapur, about the year 1068 he traveled to the province of Bukhara , where he frequented the renowned library of the Ark . In about 1070 he moved to Samarkand , where he started to compose his famous Treatise on Algebra under the patronage of Abu Tahir Abd al-Rahman ibn ʿAlaq, the governor and chief judge of the city. [ 20 ] : 4330b Khayyam was kindly received by the Karakhanid ruler Shams al-Mulk Nasr , who according to Bayhaqi, would "show him the greatest honour, so much so that he would seat [Khayyam] beside him on his throne ". [ 15 ] : 34 [ 8 ] : 47
In 1073–4 peace was concluded with Sultan Malik-Shah I who had made incursions into Karakhanid dominions. Khayyam entered the service of Malik-Shah in 1074 when he was invited by the Grand Vizier Nizam al-Mulk to meet Malik-Shah in the city of Marv . Khayyam was subsequently commissioned to set up an observatory in Isfahan and lead a group of scientists in carrying out precise astronomical observations aimed at the revision of the Persian calendar. The undertaking probably began with the opening of the observatory in 1074 and ended in 1079, [ 8 ] : 28–29 when Omar Khayyam and his colleagues concluded their measurements of the length of the year, reporting it as 365.24219858156 days. [ 5 ] Given that the length of the year is changing in the sixth decimal place over a person's lifetime, this is outstandingly accurate. For comparison, the length of the year at the end of the 19th century was 365.242196 days, while today it is 365.242190 days.
After the death of Malik-Shah and his vizier (murdered, it is thought, by the Ismaili order of Assassins ), Khayyam fell from favor at court, and as a result, he soon set out on his pilgrimage to Mecca . A possible ulterior motive for his pilgrimage reported by Al-Qifti , was a public demonstration of his faith with a view to allaying suspicions of skepticism and confuting the allegations of unorthodoxy (including possible sympathy or adherence to Zoroastrianism) levelled at him by a hostile clergy. [ 8 ] : 29 [ 8 ] : 29 [ 21 ] He was then invited by the new Sultan Sanjar to Marv, possibly to work as a court astrologer . [ 1 ] He was later allowed to return to Nishapur owing to his declining health. Upon his return, he seems to have lived the life of a recluse. [ 22 ] : 99
Omar Khayyam died at the age of 83 in his hometown of Nishapur on 4 December 1131, and he is buried in what is now the Mausoleum of Omar Khayyam . One of his disciples Nizami Aruzi relates the story that sometime during 1112–3 Khayyam was in Balkh in the company of Isfizari (one of the scientists who had collaborated with him on the Jalali calendar) when he made a prophecy that "my tomb shall be in a spot where the north wind may scatter roses over it". [ 15 ] : 36 [ 19 ] Four years after his death, Aruzi located his tomb in a cemetery in a then large and well-known quarter of Nishapur on the road to Marv. As it had been foreseen by Khayyam, Aruzi found the tomb situated at the foot of a garden-wall over which pear trees and apricot trees had thrust their heads and dropped their flowers so that his tombstone was hidden beneath them. [ 15 ] : 37
Khayyam was famous during his life as a mathematician . His surviving mathematical works include
He furthermore wrote a treatise on the binomial theorem and extracting the n th root of natural numbers, which has been lost. [ 8 ] : 197 [ 11 ] : 832a [ 24 ] : § 4 [ 25 ] : 325b–326b
Part of Khayyam's Commentary on the Difficulties Concerning the Postulates of Euclid's Elements deals with the parallel axiom . [ 6 ] : 282 The treatise of Khayyam can be considered the first treatment of the axiom not based on petitio principii , but on a more intuitive postulate. Khayyam refutes the previous attempts by other mathematicians to prove the proposition, mainly on grounds that each of them had postulated something that was by no means easier to admit than the Fifth Postulate itself. [ 24 ] : § 1 [ 25 ] : 326b–327b [ 26 ] : 75 Drawing upon Aristotle 's views, he rejects the usage of movement in geometry and therefore dismisses the different attempt by Ibn al-Haytham . [ 27 ] : 64–65 [ 28 ] : 270 [ e ] Unsatisfied with the failure of mathematicians to prove Euclid's statement from his other postulates, Khayyam tried to connect the axiom with the Fourth Postulate, which states that all right angles are equal to one another. [ 6 ] : 282
Khayyam was the first to consider the three distinct cases of acute, obtuse, and right angle for the summit angles of a Khayyam-Saccheri quadrilateral . [ 6 ] : 283 After proving a number of theorems about them, he showed that Postulate V follows from the right angle hypothesis, and refuted the obtuse and acute cases as self-contradictory. [ 28 ] : 270 [ 29 ] : 133 His elaborate attempt to prove the parallel postulate was significant for the further development of geometry, as it clearly shows the possibility of non-Euclidean geometries. The hypotheses of acute, obtuse, and right angles are now known to lead respectively to the non-Euclidean hyperbolic geometry of Gauss-Bolyai-Lobachevsky, to that of Riemannian geometry , and to Euclidean geometry . [ 30 ]
Tusi 's commentaries on Khayyam's treatment of parallels made their way to Europe. John Wallis , professor of geometry at Oxford , translated Tusi's commentary into Latin. Jesuit geometer Girolamo Saccheri , whose work ( euclides ab omni naevo vindicatus , 1733) is generally considered the first step in the eventual development of non-Euclidean geometry , was familiar with the work of Wallis. The American historian of mathematics David Eugene Smith mentions that Saccheri "used the same lemma as the one of Tusi, even lettering the figure in precisely the same way and using the lemma for the same purpose". He further says that "Tusi distinctly states that it is due to Omar Khayyam, and from the text, it seems clear that the latter was his inspirer." [ 8 ] : 195 [ 22 ] : 104 [ 31 ]
This treatise on Euclid contains another contribution dealing with the theory of proportions and with the compounding of ratios. Khayyam discusses the relationship between the concept of ratio and the concept of number and explicitly raises various theoretical difficulties. In particular, he contributes to the theoretical study of the concept of irrational number . [ 32 ] Displeased with Euclid's definition of equal ratios, he redefined the concept of a number by the use of a continued fraction as the means of expressing a ratio. Youschkevitch and Rosenfeld argue that "by placing irrational quantities and numbers on the same operational scale, [Khayyam] began a true revolution in the doctrine of number." [ 25 ] : 327b Likewise, it was noted by D. J. Struik that Omar was "on the road to that extension of the number concept which leads to the notion of the real number ." [ 6 ] : 284
Rashed and Vahabzadeh (2000) have argued that because of his thoroughgoing geometrical approach to algebraic equations, Khayyam can be considered the precursor of Descartes in the invention of analytic geometry . [ 33 ] : 248 In the Treatise on the Division of a Quadrant of a Circle Khayyam applied algebra to geometry. In this work, he devoted himself mainly to investigating whether it is possible to divide a circular quadrant into two parts such that the line segments projected from the dividing point to the perpendicular diameters of the circle form a specific ratio. His solution, in turn, employed several curve constructions that led to equations containing cubic and quadratic terms. [ 33 ] : 248
Khayyam seems to have been the first to conceive a general theory of cubic equations, [ 5 ] [ f ] and the first to geometrically solve every type of cubic equation, so far as positive roots are concerned. [ 34 ] The Treatise on Algebra contains his work on cubic equations . [ 35 ] : 9 It is divided into three parts: (i) equations which can be solved with compass and straight edge , (ii) equations which can be solved by means of conic sections , and (iii) equations which involve the inverse of the unknown. [ 24 ] : § 3
Khayyam produced an exhaustive list of all possible equations involving lines, squares, and cubes. [ 36 ] : 43 He considered three binomial equations, nine trinomial equations, and seven tetranomial equations. [ 6 ] : 281 For the first and second degree polynomials, he provided numerical solutions by geometric construction. He concluded that there are fourteen different types of cubics that cannot be reduced to an equation of a lesser degree. [ 11 ] : 831b [ 25 ] : 328a [ 37 ] : 49 For these he could not accomplish the construction of his unknown segment with compass and straight edge. He proceeded to present geometric solutions to all types of cubic equations using the properties of conic sections. [ 6 ] : 281 [ 38 ] : 157 The prerequisite lemmas for Khayyam's geometrical proof include Euclid VI , Prop 13, and Apollonius II , Prop 12. [ 38 ] : 155 The positive root of a cubic equation was determined as the abscissa of a point of intersection of two conics, for instance, the intersection of two parabolas , or the intersection of a parabola and a circle, etc. [ 39 ] : 141 However, he acknowledged that the arithmetic problem of these cubics was still unsolved, adding that "possibly someone else will come to know it after us". [ 38 ] : 158 This task remained open until the sixteenth century, where an algebraic solution of the cubic equation was found in its generality by Cardano , Del Ferro , and Tartaglia in Renaissance Italy . [ 6 ] : 282
Whoever thinks algebra is a trick in obtaining unknowns has thought it in vain. No attention should be paid to the fact that algebra and geometry are different in appearance. Algebras are geometric facts which are proved by propositions five and six of Book two of Elements .
In effect, Khayyam's work is an effort to unify algebra and geometry. [ 41 ] : 241 This particular geometric solution of cubic equations was further investigated by M. Hachtroudi and extended to solving fourth-degree equations. [ 42 ] Although similar methods had appeared sporadically since Menaechmus , and further developed by the 10th-century mathematician Abu al-Jud , [ 43 ] : 29 [ 44 ] : 110 Khayyam's work can be considered the first systematic study and the first exact method of solving cubic equations. [ 45 ] : 92 The mathematician Woepcke (1851) who offered translations of Khayyam's algebra into French praised him for his "power of generalization and his rigorously systematic procedure." [ 46 ] : 10
From the Indians one has methods for obtaining square and cube roots , methods based on knowledge of individual cases – namely the knowledge of the squares of the nine digits 1 2 , 2 2 , 3 2 (etc.) and their respective products, i.e. 2 × 3 etc. We have written a treatise on the proof of the validity of those methods and that they satisfy the conditions. In addition we have increased their types, namely in the form of the determination of the fourth, fifth, sixth roots up to any desired degree. No one preceded us in this and those proofs are purely arithmetic, founded on the arithmetic of The Elements .
In his algebraic treatise, Khayyam alludes to a book he had written on the extraction of the n {\displaystyle n} th root of natural numbers using a law he had discovered which did not depend on geometric figures. [ 39 ] This book was most likely titled the Difficulties of Arithmetic ( Mushkilāt al-Ḥisāb ), [ 11 ] : 832a [ 24 ] : § 4 and is not extant. [ 25 ] : 325b Based on the context, some historians of mathematics such as D. J. Struik, believe that Omar must have known the formula for the expansion of the binomial ( a + b ) n {\displaystyle (a+b)^{n}} , where n is a positive integer. [ 6 ] : 282 The case of power 2 is explicitly stated in Euclid's elements and the case of at most power 3 had been established by Indian mathematicians. Khayyam was the mathematician who noticed the importance of a general binomial theorem. The argument supporting the claim that Khayyam had a general binomial theorem is based on his ability to extract roots. [ 48 ] One of Khayyam's predecessors, al-Karaji , had already discovered the triangular arrangement of the coefficients of binomial expansions that Europeans later came to know as Pascal's triangle ; [ 49 ] : 60 Khayyam popularized this triangular array in Iran, so that it is now known as Omar Khayyam's triangle. [ 39 ]
In 1074–5, Omar Khayyam was commissioned by Sultan Malik-Shah to build an observatory at Isfahan and reform the Persian calendar . There was a panel of eight scholars working under the direction of Khayyam to make large-scale astronomical observations and revise the astronomical tables. [ 39 ] : 141 Recalibrating the calendar fixed the first day of the year at the exact moment of the passing of the Sun's center across vernal equinox . This marks the beginning of spring or Nowrūz , a day in which the Sun enters the first degree of Aries before noon. [ 50 ] : 10–11 [ 51 ] The resultant calendar was named in Malik-Shah's honor as the Jalālī calendar , and was inaugurated on 15 March 1079. [ 52 ] : 269 The observatory itself was disused after the death of Malik-Shah in 1092. [ 7 ] : 659
The Jalālī calendar was a true solar calendar where the duration of each month is equal to the time of the passage of the Sun across the corresponding sign of the Zodiac . The calendar reform introduced a unique 33-year intercalation cycle. As indicated by the works of Khazini , Khayyam's group implemented an intercalation system based on quadrennial and quinquennial leap years . Therefore, the calendar consisted of 25 ordinary years that included 365 days, and 8 leap years that included 366 days. [ 53 ] : 13 The calendar remained in use across Greater Iran from the 11th to the 20th centuries. In 1911, the Jalali calendar became the official national calendar of Qajar Iran . In 1925, this calendar was simplified and the names of the months were modernised, resulting in the modern Iranian calendar . The Jalali calendar is more accurate than the Gregorian calendar of 1582, [ 7 ] : 659 with an error of one day accumulating over 5,000 years, compared to one day every 3,330 years in the Gregorian calendar. [ 8 ] : 200 Moritz Cantor considered it the most perfect calendar ever devised. [ 22 ] : 101
One of his pupils, Nizami Aruzi , relates that Khayyam apparently did not have a belief in astrology and divination: "I did not observe that he ( scil. Omar Khayyam) had any great belief in astrological predictions, nor have I seen or heard of any of the great [scientists] who had such belief." [ 46 ] : 11 While working for Sultan Sanjar as an astrologer he was asked to predict the weather – a job that he apparently did not do well. [ 8 ] : 30 George Saliba explains that the term ‘ilm al-nujūm , used in various sources in which references to Khayyam's life and work could be found, has sometimes been incorrectly translated to mean astrology. He adds: "from at least the middle of the tenth century, according to Farabi 's Enumeration of the Sciences , that this science, ‘ilm al-nujūm , was already split into two parts, one dealing with astrology and the other with theoretical mathematical astronomy." [ 54 ] : 224
Khayyam has a short treatise devoted to Archimedes' principle (in full title, On the Deception of Knowing the Two Quantities of Gold and Silver in a Compound Made of the Two ). For a compound of gold adulterated with silver, he describes a method to measure more exactly the weight per capacity of each element. It involves weighing the compound both in air and in water, since weights are easier to measure exactly than volumes. By repeating the same with both gold and silver one finds exactly how much heavier than water gold, silver and the compound were. This treatise was extensively examined by Eilhard Wiedemann who believed that Khayyam's solution was more accurate and sophisticated than that of Khazini and Al-Nayrizi who also dealt with the subject elsewhere. [ 8 ] : 198
Another short treatise is concerned with music theory in which he discusses the connection between music and arithmetic. Khayyam's contribution was in providing a systematic classification of musical scales, and discussing the mathematical relationship among notes, minor, major and tetrachords . [ 8 ] : 198
The earliest allusion to Omar Khayyam's poetry is from the historian Imad al-Din al-Isfahani , a younger contemporary of Khayyam, who explicitly identifies him as both a poet and a scientist ( Kharidat al-qasr , 1174). [ 8 ] : 49 [ 55 ] : 35 One of the earliest specimens of Omar Khayyam's Rubiyat is from Fakhr al-Din al-Razi . In his work al-Tanbih ‘ala ba‘d asrar al-maw‘dat fi’l-Qur’an ( c. 1160 ), he quotes one of his poems (corresponding to quatrain LXII of FitzGerald's first edition). Daya in his writings ( Mirṣād al-‘Ibad , c. 1230) quotes two quatrains, one of which is the same as the one already reported by Razi. An additional quatrain is quoted by the historian Juvayni ( Tarikh-i Jahangushay , c. 1226–1283). [ 55 ] : 36–37 [ 8 ] : 92 In 1340 Jajarmi includes thirteen quatrains of Khayyam in his work containing an anthology of the works of famous Persian poets ( Mu’nis al-ahrār ), two of which have hitherto been known from the older sources. [ 56 ] : 434 A comparatively late manuscript is the Bodleian MS. Ouseley 140, written in Shiraz in 1460, which contains 158 quatrains on 47 folia. The manuscript belonged to William Ouseley (1767–1842) and was purchased by the Bodleian Library in 1844.
There are occasional quotes of verses attributed to Khayyam in texts attributed to authors of the 13th and 14th centuries, but these are of doubtful authenticity, so that skeptical scholars point out that the entire tradition may be pseudepigraphic . [ 55 ] : 11 Hans Heinrich Schaeder in 1934 commented that the name of Omar Khayyam "is to be struck out from the history of Persian literature" due to the lack of any material that could confidently be attributed to him. De Blois presents a bibliography of the manuscript tradition, concluding pessimistically that the situation has not changed significantly since Schaeder's time. [ 57 ] :307
Five of the quatrains later attributed to Omar Khayyam are found as early as 30 years after his death, quoted in Sindbad-Nameh . While this establishes that these specific verses were in circulation in Omar's time or shortly later, it does not imply that the verses must be his. De Blois concludes that at the least the process of attributing poetry to Omar Khayyam appears to have begun already in the 13th century. [ 57 ] :305 Edward Granville Browne (1906) notes the difficulty of disentangling authentic from spurious quatrains: "while it is certain that Khayyam wrote many quatrains, it is hardly possible, save in a few exceptional cases, to assert positively that he wrote any of those ascribed to him". [ 7 ] : 663
In addition to the Persian quatrains, there are twenty-five Arabic poems attributed to Khayyam which are attested by historians such as al-Isfahani, Shahrazuri ( Nuzhat al-Arwah , c. 1201–1211), Qifti ( Tārikh al-hukamā , 1255), and Hamdallah Mustawfi ( Tarikh-i guzida , 1339). [ 8 ] : 39
Boyle emphasized that there are a number of other Persian scholars who occasionally wrote quatrains, including Avicenna , Ghazali , and Tusi . They conclude that it is also possible that for Khayyam poetry was an amusement of his leisure hours: "these brief poems seem often to have been the work of scholars and scientists who composed them, perhaps, in moments of relaxation to edify or amuse the inner circle of their disciples". [ 7 ] : 662
The poetry attributed to Omar Khayyam has contributed greatly to his popular fame in the modern period as a direct result of the extreme popularity of the translation of such verses into English by Edward FitzGerald (1859). FitzGerald's Rubaiyat of Omar Khayyam contains loose translations of quatrains from the Bodleian manuscript. It enjoyed such success in the fin de siècle period that a bibliography compiled in 1929 listed more than 300 separate editions, [ 58 ] and many more have been published since. [ 57 ] :312
Khayyam considered himself intellectually to be a student of Avicenna . [ 2 ] : 474 According to Al-Bayhaqi, he was reading the metaphysics in Avicenna's the Book of Healing before he died. [ 7 ] : 661 There are six philosophical papers believed to have been written by Khayyam. One of them, On existence ( Fi’l-wujūd ), was written originally in Persian and deals with the subject of existence and its relationship to universals. Another paper, titled The necessity of contradiction in the world, determinism and subsistence ( Darurat al-tadād fi’l-‘ālam wa’l-jabr wa’l-baqā’ ), is written in Arabic and deals with free will and determinism . [ 2 ] : 475 The titles of his other works are On being and necessity ( Risālah fī’l-kawn wa’l-taklīf ), The Treatise on Transcendence in Existence ( al-Risālah al-ulā fi’l-wujūd ), On the knowledge of the universal principles of existence ( Risālah dar ‘ilm kulliyāt-i wujūd ), and Abridgement concerning natural phenomena ( Mukhtasar fi’l-Tabi‘iyyāt ).
Khayyam himself once said: [ 59 ] : 431
We are the victims of an age when men of science are discredited, and only a few remain who are capable of engaging in scientific research. Our philosophers spend all their time in mixing true with false and are interested in nothing but outward show; such little learning as they have they extend on material ends. When they see a man sincere and unremitting in his search for the truth, one who will have nothing to do with falsehood and pretence, they mock and despise him.
A literal reading of Khayyam's quatrains leads to the interpretation of his philosophic attitude toward life as a combination of pessimism , nihilism , Epicureanism , fatalism , and agnosticism . [ 8 ] : 6 [ 60 ] This view is taken by Iranologists such as Arthur Christensen , Hans Heinrich Schaeder , John Andrew Boyle , Edward Denison Ross , [ 61 ] : 365 Edward Henry Whinfield [ 46 ] : 40 and George Sarton . [ 18 ] : 18 Conversely, the Khayyamic quatrains have also been described as mystical Sufi poetry. [ 62 ] In addition to his Persian quatrains, J. C. E. Bowen mentions that Khayyam's Arabic poems also "express a pessimistic viewpoint which is entirely consonant with the outlook of the deeply thoughtful rationalist philosopher that Khayyam is known historically to have been." [ 63 ] : 69 Edward FitzGerald emphasized the religious skepticism he found in Khayyam. [ 64 ] In his preface to the Rubáiyát he claimed that he "was hated and dreaded by the Sufis", [ 65 ] and denied any pretense at divine allegory: "his Wine is the veritable Juice of the Grape: his Tavern, where it was to be had: his Saki , the Flesh and Blood that poured it out for him." [ 66 ] : 62 Sadegh Hedayat is one of the most notable proponents of Khayyam's philosophy as agnostic skepticism, and according to Jan Rypka (1934), he even considered Khayyam an atheist . [ 67 ] Hedayat (1923) states that "while Khayyam believes in the transmutation and transformation of the human body, he does not believe in a separate soul; if we are lucky, our bodily particles would be used in the making of a jug of wine." [ 68 ] : 138 Omar Khayyam's poetry has been cited in the context of New Atheism , such as in The Portable Atheist by Christopher Hitchens . [ 69 ] : 7
Al-Qifti ( c. 1172–1248 ) appears to confirm this view of Khayyam's philosophy. [ 7 ] : 663 In his work The History of Learned Men he reports that Khayyam's poems were only outwardly in the Sufi style, but were written with an anti-religious agenda. [ 61 ] : 365 He also mentions that he was at one point indicted for impiety, but went on a pilgrimage to prove he was pious. [ 8 ] : 29 The report has it that upon returning to his native city he concealed his deepest convictions and practised a strictly religious life, going morning and evening to the place of worship. [ 61 ] : 355 Khayyam on the Koran (quote 84): [ 70 ]
The Koran! well, come put me to the test, Lovely old book in hideous error drest, Believe me, I can quote the Koran too, The unbeliever knows his Koran best. And do you think that unto such as you, A maggot-minded, starved, fanatic crew, God gave the Secret, and denied it me? Well, well, what matters it! believe that too.
Look not above, there is no answer there; Pray not, for no one listens to your prayer; Near is as near to God as any Far, And Here is just the same deceit as There. [ 70 ]
Men talk of heaven,—there is no heaven but here; Men talk of hell,—there is no hell but here; Men of hereafters talk, and future lives, O love, there is no other life—but here. [ 70 ]
An account of him, written in the thirteenth century, shows him as "versed in all the wisdom of the Greeks," and as wont to insist on the necessity of studying science on Greek lines. Of his prose works, two, which were stand authority, dealt respectively with precious stones and climatology. Beyond question the poet-astronomer was undevout; and his astronomy doubtless helped to make him so. One contemporary writes: "I did not observe that he had any great belief in astrological predictions; nor have I seen or heard of any of the great (scientists) who had such belief. He gave his adherence to no religious sect. Agnosticism, not faith, is the keynote of his works. Among the sects he saw everywhere strife and hatred in which he could have no part...." [ 71 ] : 263, vol. 1
Persian novelist Sadegh Hedayat says Khayyám from "his youth to his death remained a materialist, pessimist, agnostic. Khayyam looked at all religions questions with a skeptical eye", continues Hedayat, "and hated the fanaticism, narrow-mindedness, and the spirit of vengeance of the mullas, the so-called religious scholars." [ 72 ] : 13
In the context of a piece entitled On the Knowledge of the Principles of Existence , Khayyam endorses the Sufi path. [ 8 ] : 8 Csillik suggests the possibility that Omar Khayyam could see in Sufism an ally against orthodox religiosity. [ 73 ] : 75 Other commentators do not accept that Khayyam's poetry has an anti-religious agenda and interpret his references to wine and drunkenness in the conventional metaphorical sense common in Sufism. The French translator J. B. Nicolas held that Khayyam's constant exhortations to drink wine should not be taken literally, but should be regarded rather in the light of Sufi thought where rapturous intoxication by "wine" is to be understood as a metaphor for the enlightened state or divine rapture of baqaa . [ 74 ] The view of Omar Khayyam as a Sufi was defended by Bjerregaard, [ 75 ] : 3 Idries Shah , [ 76 ] : 165–166 and Dougan who attributes the reputation of hedonism to the failings of FitzGerald's translation, arguing that Khayyam's poetry is to be understood as "deeply esoteric". [ 77 ] On the other hand, Iranian experts such as Mohammad Ali Foroughi and Mojtaba Minovi rejected the hypothesis that Omar Khayyam was a Sufi. [ 63 ] : 72 Foroughi stated that Khayyam's ideas may have been consistent with that of Sufis at times but there is no evidence that he was formally a Sufi . Aminrazavi states that "Sufi interpretation of Khayyam is possible only by reading into his Rubāʿīyyāt extensively and by stretching the content to fit the classical Sufi doctrine.". [ 8 ] : 128 Furthermore, Boyle emphasizes that Khayyam was intensely disliked by a number of celebrated Sufi mystics who belonged to the same century. This includes Shams Tabrizi (spiritual guide of Rumi ), [ 8 ] : 58 Najm al-Din Daya who described Omar Khayyam as "an unhappy philosopher, atheist, and materialist", [ 63 ] : 71 and Attar who regarded him not as a fellow-mystic but a free-thinking scientist who awaited punishments hereafter. [ 7 ] : 663–664
Seyyed Hossein Nasr argues that it is "reductive" to use a literal interpretation of his verses (many of which are of uncertain authenticity to begin with) to establish Omar Khayyam's philosophy. Instead, he adduces Khayyam's interpretive translation of Avicenna 's treatise Discourse on Unity ( al-Khutbat al-Tawhīd ), where he expresses orthodox views on Divine Unity in agreement with the author. [ 78 ] : Ch. 9, 165–183 The prose works believed to be Khayyam's are written in the Peripatetic style and are explicitly theistic, dealing with subjects such as the existence of God and theodicy . [ 8 ] : 160 As noted by Bowen these works indicate his involvement in the problems of metaphysics rather than in the subtleties of Sufism. [ 63 ] : 71 As evidence of Khayyam's faith and/or conformity to Islamic customs, Aminrazavi mentions that in his treatises he offers salutations and prayers, praising God and Muhammad . In most biographical extracts, he is referred to with religious honorifics such as Imām , The Patron of Faith ( Ghīyāth al-Dīn ), and The Evidence of Truth ( Hujjat al-Haqq ). [ 8 ] He also notes that biographers who praise his religiosity generally avoid making reference to his poetry, while the ones who mention his poetry often do not praise his religious character. [ 8 ] : 48 For instance, Al-Bayhaqi's account, which antedates by some years other biographical notices, speaks of Omar as a very pious man who professed orthodox views down to his last hour. [ 17 ] : 174
On the basis of all the existing textual and biographical evidence, the question remains somewhat open, [ 8 ] : 11 and as a result Khayyam has received sharply conflicting appreciations and criticisms. [ 61 ] : 350
The various biographical extracts referring to Omar Khayyam describe him as unequalled in scientific knowledge and achievement during his time. [ g ] Many called him by the epithet King of the Wise ( Arabic : ملك الحکماء , romanized : Malik al-Ḥukamā ). [ 56 ] : 436 [ 39 ] : 141 Shahrazuri (d. 1300) esteems him highly as a mathematician, and claims that he may be regarded as "the successor of Avicenna in the various branches of philosophic learning". [ 61 ] : 352 Al-Qifti (d. 1248), even though disagreeing with his views, concedes he was "unrivalled in his knowledge of natural philosophy and astronomy". [ 61 ] : 355 Despite being hailed as a poet by a number of biographers, according to John Andrew Boyle "it is still possible to argue that Khayyam's status as a poet of the first rank is a comparatively late development." [ 7 ] : 663
Thomas Hyde was the first European to call attention to Khayyam and to translate one of his quatrains into Latin ( Historia religionis veterum Persarum eorumque magorum , 1700). [ 79 ] : 525 Western interest in Persia grew with the Orientalism movement in the 19th century. Joseph von Hammer-Purgstall (1774–1856) translated some of Khayyam's poems into German in 1818, and Gore Ouseley (1770–1844) into English in 1846, but Khayyam remained relatively unknown in the West until after the publication of Edward FitzGerald 's Rubaiyat of Omar Khayyam in 1859. FitzGerald's work at first was unsuccessful but was popularised by Whitley Stokes from 1861 onward, and the work came to be greatly admired by the Pre-Raphaelites . In 1872 FitzGerald had a third edition printed which increased interest in the work in America. By the 1880s, the book was extremely well known throughout the English-speaking world, to the extent of the formation of numerous "Omar Khayyam Clubs" and a "fin de siècle cult of the Rubaiyat". [ 80 ] : 202 Khayyam's poems have been translated into many languages; many of the more recent ones are more literal than that of FitzGerald. [ 81 ]
FitzGerald's translation was a factor in rekindling interest in Khayyam as a poet even in his native Iran. [ 82 ] : 55–72 Sadegh Hedayat in his Songs of Khayyam ( Taranehha-ye Khayyam , 1934) reintroduced Khayyam's poetic legacy to modern Iran. Under the Pahlavi dynasty , a new monument of white marble, designed by the architect Houshang Seyhoun , was erected over his tomb. A statue by Abolhassan Sadighi was erected in Laleh Park , Tehran in the 1960s, and a bust by the same sculptor was placed near Khayyam's mausoleum in Nishapur. In 2009, the state of Iran donated a pavilion to the United Nations Office in Vienna , inaugurated at Vienna International Center . [ 83 ] In 2016, three statues of Khayyam were unveiled: one at the University of Oklahoma , one in Nishapur and one in Florence, Italy. [ 84 ] Over 150 composers have used the Rubaiyat as their source of inspiration. The earliest such composer was Liza Lehmann . [ 85 ]
FitzGerald rendered Khayyam's name as "Tentmaker", and the anglicized name of "Omar the Tentmaker" resonated in English-speaking popular culture for a while. Thus, Nathan Haskell Dole published a novel called Omar, the Tentmaker: A Romance of Old Persia in 1898. Omar the Tentmaker of Naishapur is a historical novel by John Smith Clarke, published in 1910. "Omar the Tentmaker" is also the title of a 1914 play by Richard Walton Tully in an oriental setting, adapted as a silent film in 1922. US General Omar Bradley was given the nickname "Omar the Tent-Maker" in World War II. [ 86 ] : 13
The diverse talents and intellectual pursuits of Khayyam captivated many Ottoman and Turkish writers throughout history. [ 87 ] Scholars often viewed Khayyam as a means to enhance their own poetic prowess and intellectual depth, drawing inspiration and recognition from his writings. [ 88 ] For many Muslim reformers, Khayam's verses provided a counterpoint to the conservative norms prevalent in Islamic societies, allowing room for independent thought and a libertine lifestyle. [ 88 ] Figures like Abdullah Cevdet , Rıza Tevfik , and Yahya Kemal utilized Khayyam's themes to justify their progressive ideologies or to celebrate liberal aspects of their lives, portraying him as a cultural, political, and intellectual role model who demonstrated Islam's compatibility with modern conventions. [ 88 ] Similarly, Turkish leftist poets and intellectuals, including Nâzım Hikmet , Sabahattin Eyüboğlu , A. Kadir, and Gökçe, appropriated Khayyam to champion their socialist worldview, imbuing his voice with a humanistic tone in the vernacular. [ 88 ] Khayyam's resurgence in spoken Turkish since the 1980s has transformed him into a poet of the people, with numerous books and translations revitalizing his historical significance. [ 88 ] Conversely, scholars like Dāniş, Tevfik, and Gölpınarlı advocated for source criticism and the identification of authentic quatrains to discern the genuine Khayyam amidst historical perceptions of his sociocultural image. [ 88 ]
The quatrain by Omar Khayyam known as "The Moving Finger", in the form of its translation by the English poet Edward Fitzgerald is one of the most popular quatrains in the Anglosphere . [ 89 ] It reads:
The Moving Finger writes; and having writ,
Moves on: nor all your Piety nor Wit
Shall lure it back to cancel half a Line,
Nor all your Tears wash out a Word of it. [ 90 ] [ h ]
The title of the novel The Moving Finger written by Agatha Christie and published in 1942 was inspired by this quatrain of the translation of Rubaiyat of Omar Khayyam by Edward Fitzgerald . [ 89 ] Martin Luther King also cites this quatrain of Omar Khayyam in one of his speeches, " Beyond Vietnam: A Time to Break Silence ": [ 89 ] [ 91 ]
“We may cry out desperately for time to pause in her passage, but time is adamant to every plea and rushes on. Over the bleached bones and jumbled residues of numerous civilizations are written the pathetic words, ‘Too late.’ There is an invisible book of life that faithfully records our vigilance or our neglect. Omar Khayyam is right: ‘The moving finger writes, and having writ moves on.’”
In one of his apologetic speeches about the Clinton–Lewinsky scandal , Bill Clinton , the 42nd president of the US, also cites this quatrain. [ 89 ] [ 92 ]
In 1934 Harold Lamb published a historical novel Omar Khayyam . The French-Lebanese writer Amin Maalouf based the first half of his historical fiction novel Samarkand on Khayyam's life and the creation of his Rubaiyat. The sculptor Eduardo Chillida produced four massive iron pieces titled Mesa de Omar Khayyam (Omar Khayyam's Table) in the 1980s. [ 93 ] [ 94 ]
The lunar crater Omar Khayyam was named in his honour in 1970, as was the minor planet 3095 Omarkhayyam discovered by Soviet astronomer Lyudmila Zhuravlyova in 1980. [ 95 ]
Google has released two Google Doodles commemorating him. The first was on his 964th birthday on 18 May 2012. The second was on his 971st birthday on 18 May 2019. [ 96 ]
بر لوح نشان بودنیها بودهست
پیوسته قلم ز نیک و بد فرسودهست
در روز ازل هر آنچه بایست بداد
غم خوردن و کوشیدن ما بیهودهست | https://en.wikipedia.org/wiki/Omar_Khayyam |
Omar M. Yaghi ( Arabic : عمر مونّس ياغي ; born February 9, 1965) is the James and Neeltje Tretter Chair Professor of Chemistry at the University of California, Berkeley , an affiliate scientist at Lawrence Berkeley National Laboratory , the founding director of the Berkeley Global Science Institute , and an elected member of the US National Academy of Sciences [ 1 ] as well as the German National Academy of Sciences Leopoldina . [ 2 ]
Yaghi was born in Amman , Jordan, in 1965, to a refugee family originally from Mandatory Palestine . [ 3 ] [ 4 ] [ 5 ] He grew up in a household with many children, all living together in a single room with the family's livestock, [ 6 ] with limited access to clean water and without electricity. [ 7 ] At the age of 15, he moved to the United States at the encouragement of his father. [ 8 ] Although he knew little English, he began classes at Hudson Valley Community College , and later transferred to the University at Albany, SUNY , to finish his college degree. He began his graduate studies at University of Illinois , Urbana-Champaign, and received his PhD in 1990 under the guidance of Walter G. Klemperer . [ 9 ] He was a National Science Foundation postdoctoral fellow at Harvard University (1990–1992) with Richard H. Holm . In 2021, Yaghi was granted Saudi citizenship.
He was on the faculties of Arizona State University (1992–1998) as an assistant professor, the University of Michigan (1999–2006) as the Robert W. Parry Professor of Chemistry, and the University of California, Los Angeles (2007–2012) as the Christopher S. Foote Professor of Chemistry as well as holding the Irving and Jean Stone Chair in Physical Sciences. [ 10 ]
In 2012, he moved to the University of California, Berkeley , where he is now the James and Neeltje Tretter Professor of Chemistry. He was the director of the Molecular Foundry at Lawrence Berkeley National Laboratory from 2012 through 2013. He is the Founding Director of the Berkeley Global Science Institute. He is also a co-director of the Kavli Energy NanoSciences Institute of the University of California, Berkeley, and the Lawrence Berkeley National Laboratory, the California Research Alliance by BASF , as well as the Bakar Institute of Digital Materials for the Planet. [ 11 ]
See also main article on reticular materials
Yaghi pioneered reticular chemistry, a new field of chemistry concerned with stitching molecular building blocks together by strong bonds to make open frameworks. [ 12 ] [ 13 ] [ 14 ] As stated by the International Balzan Prize Foundation, Omar Yaghi suggested the idea of using molecular building blocks and strong bonds to form crystalline materials in the early 1990s. At the time, the scientific community considered this idea chemically unfeasible, as the synthesis of strong bonding between molecular components usually led to poorly defined, amorphous solids. However, in 1995, Yaghi successfully crystallized metal-organic structures where metal ions are joined by charged organic linkers as exemplified by carboxylates to form strong bonds. This discovery paved the way for the development of a new class of materials: Metal-Organic Frameworks (MOFs), and thus it marked the start of reticular chemistry. [ 15 ]
His most recognizable work is in the design, synthesis, application, and popularisation of metal-organic frameworks (MOFs). By IUPAC recommendation, MOF is considered a subclass of the coordination polymers first reported in 1959 by Yoshihiko Saito and colleagues. [ 16 ] This is followed by E. A. Tomic in 1965 when he published a report titled "Thermal stability of coordination polymers" where he synthesized and characterized many coordination polymers constructed with different ligands and various metal ions. [ 17 ] Hans-Peter Werner and colleagues in 1986 published a coordination polymer 2,5-Dimethyl-N,N′-dicyanoquinonediimine and evaluated its electrical conductivity, [ 18 ] and in 1989 Bernard Hoskins [ 19 ] and Richard Robson [ 20 ] [ 21 ] reported a coordination polymer consisting of three dimensionally linked rod-like segments. In general, coordination polymers are frail disordered structures with poorly defined properties. [ 22 ]
In the 1990s, Omar M. Yaghi made three breakthroughs that transformed the traditional coordination polymers into architecturally robust and permanently porous MOFs which are being widely used today: (1) crystallization of metal-organic structures where metal ions are joined by charged organic linkers as exemplified by carboxylates to form strong bonds (published in 1995); [ 24 ] (2) introduction of metal-carboxylate clusters as secondary building units (SBUs), which was the key to building architecturally robust frameworks exhibiting permanent porosity as he proved by measuring for the first time their gas adsorption isotherms (published in 1998); [ 25 ] (3) realization of ultra-high porosity with MOF-5 (published in 1999). [ 26 ] In essence, the strong bonds holding the MOFs allow for their structural robustness, ultra-high porosity, and longevity in industrial applications.
Omar M. Yaghi published the first paper of covalent organic frameworks (COFs) in 2005, reporting a series of 2D COFs. [ 28 ] He reported the design and successful synthesis of COFs by condensation reactions of phenyl diboronic acid (C 6 H 4 [B(OH) 2 ] 2 ) and hexahydroxytriphenylene (C 18 H 6 (OH) 6 ). Powder X-ray diffraction studies of the highly crystalline products having empirical formulas (C 3 H 2 BO) 6 ·(C 9 H 12 ) 1 (COF-1) and C 9 H 4 BO 2 (COF-5) revealed 2-dimensional expanded porous graphitic layers that have either staggered conformation (COF-1) or eclipsed conformation (COF-5). Their crystal structures are entirely held by strong bonds between B, C, and O atoms to form rigid porous architectures with pore sizes ranging from 7 to 27 angstroms . COF-1 and COF-5 exhibit high thermal stability (to temperatures up to 500 to 600 °C), permanent porosity, and high surface areas (711 and 1590 square meters per gram, respectively). [ 29 ] The synthesis of 3D COFs has been hindered by longstanding practical and conceptual challenges until it was first achieved in 2007 by Omar M. Yaghi. [ 30 ]
Yaghi is also known for the design and production of a new class of compounds known as zeolitic imidazolate frameworks (ZIFs). MOFs, COFs, ZIFs are noted for their extremely high surface areas ( 5640 m 2 /g for MOF-177) [ 31 ] and very low crystalline densities ( 0.17 g·cm −3 for COF-108). [ 32 ]
Yaghi also pioneered molecular weaving, and synthesized the world's first material woven at the atomic and molecular levels (COF-505). [ 34 ] [ 35 ]
He has been leading the effort in applying these materials in clean energy technologies including hydrogen and methane storage, [ 36 ] [ 37 ] carbon dioxide capture and storage, [ 38 ] [ 39 ] as well as harvesting water from desert air. [ 40 ]
According to a Thomson Reuters analysis, Yaghi was the second most cited chemist in the world from 2000 to 2010. [ 41 ]
In 2020, Yaghi founded Atoco, a California-based startup, [ 42 ] aiming to commercialize the latest advancements and discoveries by Yaghi in MOFs and COFs technologies in the field of carbon capture and atmospheric water harvesting . [ 43 ] [ 44 ]
In 2021, Yaghi co-founded another startup called H2MOF, dedicated to solving the challenges associated with hydrogen storage by utilizing the latest discoveries by Yaghi in the field of reticular chemistry. [ 45 ] [ 46 ]
Yaghi has received several global awards and medals throughout his career, including the Albert Einstein World Award of Science in 2017; the Wolf Prize in Chemistry in 2018; the Gregory Aminoff Prize in 2019; the VinFuture Prize in 2022, and the Science for the Future Ernest Solvay Prize in 2024. The following are among the key awards, medals and recognitions Yaghi received: | https://en.wikipedia.org/wiki/Omar_M._Yaghi |
The Omate TrueSmart is a smartwatch designed by Omate , a Chinese company based in Hong Kong and Shenzhen . It has been funded by crowd funding via Kickstarter . The funding period was from August 21, 2013 until September 20, 2013. The funding goal of $100,000 was reached within 12 hours, with more than $1,032,000 raised by the end of the campaign. In contrast to other smartwatches, the Omate is a complete standalone telecom mobile device that can be used to make calls, navigate and use Android apps independent of the user's smartphone.
The TrueSmart is powered by an ARMv7 MediaTek MT6572 chipset running Android 4.2.2 and a ROM also known as OUI - Omate User Interface.
The body of 45 mm × 45 mm × 14 mm has two side buttons for Power and Home functions. It also features a 3 megapixel camera module which is upscaled by software from 3 megapixel to 5 megapixel. In contrast to other smart watches, the TrueSmart is a standalone smartwatch that can support 3G GSM micro SIM card. The TrueSmart is a full featured Android smartphone in a watch form factor promoted as a smartwatch 2.0 (Telecom Wearable) by Omate to differentiate the device with other traditional smart watches which are mainly companion devices.
Its sensors include a magnetometer , a three-axis accelerometer and a GPS. It has a vibrator, a microphone and an audio speaker. The watch is charged and connected to computers using a standard USB cable and an external charging cradle accessory. [ 2 ]
It is powered by a dual-core ARM Cortex-A7 MediaTek MTK6572 processor running at 1 GHz (1.3 GHz according to kickstarter specs). [ 1 ] The GPU is a Mali 400.
It runs Android 4.2.2 with the customized Omate User Interface (OUI 2.1). The TrueSmart ecosystem includes basic Android applications: Settings / Phone / Email / Messaging / Contact / File Manager / Camera / Gallery and several third parties apps which are available in Omate own application store called the Ostore.
The Ostore features several categories [ 3 ] System firmware updates are provided over-the-air .
It has an LG 1.54-inch 240 × 240 pixel color IPS TFT display and a multi point touch panel covered with sapphire glass coating. [ 4 ]
The battery is a removable 600 mAH li-ion battery, providing for 240 minutes talk time in standalone mode and 100 hours of standby time. Removing or replacing the battery will void the device's warranty. OK stickers are placed on the back plate screws.
It has either 512 MB or 1 GB depending on the model [ 5 ] of memory and 4 GB or 8 GB of storage, expandable with up to 128 GB microSD cards.
The Omate TrueSmart is IP67 certified and dustproof. However water damages are not covered by the warranty as long as the device can be opened to insert a SIM card, an SD card or to replace the battery. The case is steel alloy or aluminum based, the glass is protected by a sapphire crystal coating, the straps are silicone. The straps are not replaceable since the GSM and GPS antennas are integrated into them. Measurements are 45 mm × 45 mm × 14 mm.
The TrueSmart is an Android-based GSM standalone smartwatch which features a micro-SIM slot. There are two versions, for different regional 3G networks: a 2100 MHz (Europe) and a 1900 MHz (US), both supporting UMTS, HSDPA, HSUPA, HSPA, and HSPA+. The 2G modem in both versions supports quad band: 900/1800/ 850/1900 GSM, GPRS, and EDGE. It has Bluetooth 3.0 (4.0 when OS is upgraded to 4.3 or newer) and Wi-Fi 802.11b/g/n connectivity.
Omate launched a Kickstarter campaign on August 21, 2013 , with an initial fundraising target of $100,000. Backers spending $199 would receive an Omate TrueSmart when they became available ($179 for the first 500 backers and $189 for the next 500 backers).
The project had met the $100,000 goal in half a day. [ 6 ] Just before the end of the campaign, over $1 million was reached.
During the Kickstarter campaign, Omate claimed the TrueSmart will run Google Play, with the heading of the first Kickstarter update being "Yes, Google Play Apps Store!". [ 22 ] However, an article on Phandroid revealed the watch cannot ship with official Google Services support due to it not meeting the Android Compatibility Definition Document requirements. [ 23 ]
However, Omate did not update their campaign to state the lack of Google certification before the campaign ended. It was not until 22 October 2013, a month after the Kickstarter campaign ended, that Omate acknowledged that the TrueSmart will not be able to pass the Google Certification after receiving official feedback from Google [ 24 ]
Therefore, the TrueSmart shipped without the Google Apps and Omate did not support any side loading but instead created its own Application Store called the Ostore featuring less than 50 apps in multiple categories, but including third party application stores such as Aptoide and 1mobilemarket. [ 25 ] | https://en.wikipedia.org/wiki/Omate_TrueSmart |
In mathematical logic , an omega-categorical theory is a theory that has exactly one countably infinite model up to isomorphism . Omega-categoricity is the special case κ = ℵ 0 {\displaystyle \aleph _{0}} = ω of κ-categoricity , and omega-categorical theories are also referred to as ω-categorical . The notion is most important for countable first-order theories.
Many conditions on a theory are equivalent to the property of omega-categoricity. In 1959 Erwin Engeler , Czesław Ryll-Nardzewski and Lars Svenonius , proved several independently. [ 1 ] Despite this, the literature still widely refers to the Ryll-Nardzewski theorem as a name for these conditions. The conditions included with the theorem vary between authors. [ 2 ] [ 3 ]
Given a countable complete first-order theory T with infinite models, the following are equivalent:
The theory of any countably infinite structure which is homogeneous over a finite relational language is omega-categorical. [ 5 ] More generally, the theory of the Fraïssé limit of any uniformly locally finite Fraïssé class is omega-categorical. [ 6 ] Hence, the following theories are omega-categorical:
This mathematical logic -related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Omega-categorical_theory |
Omega Chi Epsilon (or ΩΧΕ , sometimes simplified to OXE ) is an International honor society for chemical engineering students.
The first chapter of Omega Chi Epsilon was formed at the University of Illinois in 1931 by a group of chemical engineering students. These Founders were: [ 1 ]
Professors D.B. Keyes and Norman Krase supported the students in their efforts. The Beta chapter was formed in the Iowa State University 1932. [ 2 ]
The society grew slowly at first. Baird's Manual indicates there were six chapters by 1957, of which three were inactive. However, interest was revived in the 1960s, allowing a sustained growth that has continued to the present day. There are approximately eighty active chapters of the society as of 2021.
Omega Chi Epsilon amended its constitution to permit women to become members as of 1966. [ 2 ] The organization became a member of the Association of College Honor Societies in 1967. [ 2 ]
The society's name comes from its motto " Ode Chrototos Eggegramai " or "In this Society, professionalism is engraved in our minds". [ 1 ] The Greek letters ΩΧΕ were chosen to stand for "Order of Chemical Engineers". [ 1 ]
The society's official seal is made of two concentric circles, bearing at the top, center the words "Omega Chi Epsilon" with the words "Founded, 1931" at the bottom center. The letters of the society appear in the center of the seal. The society's colors are black, white, and maroon. [ 2 ]
The society's badge is a black Maltese cross background, on which is superimposed a circular maroon crest . The crest bears the letters ΩΧΕ on a white band passing across the horizontal midline. Above the white band are two crossed retorts rendered in gold. Below the white band are a gold integral sign and a lightning bolt. These symbols are noted to represent the roles of chemistry, mathematics, and physics in chemical engineering. [ 2 ]
Chapter traditions of service to their chemical engineering departments commonly prevail rather than broader, national traditions. [ 2 ]
Membership is limited to chemical engineering juniors, seniors, and graduate students. Associate membership may be offered to professors or other members of the staff of institutions within the field. [ 2 ]
Omega Chi Epsilon has chartered 80 chapters at colleges and universities in the United States, Qatar , and the United Arab Emirates . [ 2 ] [ 1 ]
The Society's annual meeting is held at the same time and place as the annual meeting of the American Institute of Chemical Engineers .
Governance is vested in a national president, vice president, executive secretary, and treasurer. With the immediate past president, these constitute the Executive Committee. [ 1 ] The current national president is Christi Luks of the Missouri University of Science and Technology . | https://en.wikipedia.org/wiki/Omega_Chi_Epsilon |
The omega constant is a mathematical constant defined as the unique real number that satisfies the equation
It is the value of W (1) , where W is Lambert's W function . The name is derived from the alternate name for Lambert's W function, the omega function . The numerical value of Ω is given by
The defining identity can be expressed, for example, as
or
as well as
One can calculate Ω iteratively , by starting with an initial guess Ω 0 , and considering the sequence
This sequence will converge to Ω as n approaches infinity. This is because Ω is an attractive fixed point of the function e − x .
It is much more efficient to use the iteration
because the function
in addition to having the same fixed point, also has a derivative that vanishes there. This guarantees quadratic convergence; that is, the number of correct digits is roughly doubled with each iteration.
Using Halley's method , Ω can be approximated with cubic convergence (the number of correct digits is roughly tripled with each iteration): (see also Lambert W function § Numerical evaluation ).
An identity due to Victor Adamchik [ citation needed ] is given by the relationship
Other relations due to Mező [ 1 ] [ 2 ] and Kalugin-Jeffrey-Corless [ 3 ] are:
The latter two identities can be extended to other values of the W function (see also Lambert W function § Representations ).
The constant Ω is transcendental . This can be seen as a direct consequence of the Lindemann–Weierstrass theorem . For a contradiction, suppose that Ω is algebraic. By the theorem, e −Ω is transcendental, but Ω = e −Ω , which is a contradiction. Therefore, it must be transcendental. [ 4 ] | https://en.wikipedia.org/wiki/Omega_constant |
Omega oxidation ( ω-oxidation ) is a process of fatty acid metabolism in some species of animals. It is an alternative pathway to beta oxidation that, instead of involving the β carbon, involves the oxidation of the ω carbon (the carbon most distant from the carboxyl group of the fatty acid). The process is normally a minor catabolic pathway for medium-chain fatty acids (10-12 carbon atoms), but becomes more important when β oxidation is defective.
In vertebrates, the enzymes for ω oxidation are located in the smooth ER of liver and kidney cells, instead of in the mitochondria as with β oxidation. The steps of the process are as follows:
After these three steps, either end of the fatty acid can be attached to coenzyme A . The molecule can then enter the mitochondrion and undergo β oxidation. The final products after successive oxidations include succinic acid , which can enter the citric acid cycle , and adipic acid .
The first step in ω-oxidation, i.e. addition of a hydroxy residue to the omega carbon of short, intermediate, and long chain unsaturated or saturated fatty acids, can serve to produce or inactivate signaling molecules. In humans, a subset of Cytochrome P450 (CYP450) microsome -bound ω-hydroxylases (termed Cytochrome P450 omega hydroxylases ) metabolize arachidonic acid (also known as eicosatetraenoic acid) to 20-hydroxyeicosatetraenoic acid (20-HETE). [ 1 ] 20-HETE possesses a range of activities in animal and cellular model systems, e.g. it constricts blood vessels, alters the kidney's reabsorption of salt and water, and promotes the growth of cancer cells; genetic studies in humans suggest that 20-HETE contributes to hypertension , myocardial infarction , and brain stroke (see 20-Hydroxyeicosatetraenoic acid ). Among the CYP450 superfamily, members of the CYP4A and CYP4F subfamilies viz., CYP4A11 , CYP4F2 , CYP4F3 , are considered the predominant cytochrome P450 enzymes responsible in most tissues for forming 20-HETE. [ 2 ] [ 3 ] [ 4 ] CYP2U1 [ 5 ] and CYP4Z1 [ 6 ] contribute to 20-HETE production in a more limited range of tissues. The cytochrome ω-oxidases including those belonging to the CYP4A and CYP4F sub-families and CYPU21 also ω-hydroxylate and thereby reduce the activity of various fatty acid metabolites of arachidonic acid including LTB4 , 5-HETE , 5-oxo-eicosatetraenoic acid , 12-HETE , and several prostaglandins that are involved in regulating various inflammatory, vascular, and other responses in animals and humans. [ 6 ] [ 7 ] This hydroxylation-induced inactivation may underlie the proposed roles of the cytochromes in dampening inflammatory responses and the reported associations of certain CYP4F2 and CYP4F3 single nucleotide variants with human Crohn's disease and Celiac disease , respectively. [ 8 ] [ 9 ] [ 10 ] | https://en.wikipedia.org/wiki/Omega_oxidation |
Omidubicel , sold under the brand name Omisirge , is a blood-based cell therapy used for the treatment of blood cancers . [ 3 ] [ 4 ] [ 5 ] Omidubicel is a nicotinamide -modified allogeneic hematopoietic progenitor cell therapy derived from cord blood . [ 3 ]
The most common adverse reactions include infections, graft-versus-host disease , and infusion reactions. [ 3 ]
Omidubicel is composed of human allogeneic stem cells from umbilical cord blood that are processed and cultured with nicotinamide (a form of vitamin B3). [ 3 ] Each dose is patient-specific, containing healthy stem cells from an allogeneic pre-screened donor, meaning it comes from a different individual rather than using the patient's own cells. [ 3 ] Omidubicel was approved for medical use in the United States in April 2023. [ 3 ] [ 6 ]
Omidubicel is indicated for use in people twelve years of age and older with blood cancers (hematologic malignancies) planned for umbilical cord blood transplantation following myeloablative conditioning to reduce the time to neutrophil recovery and the incidence of infection. [ 3 ] [ 6 ]
The US Food and Drug Administration (FDA) evaluated the safety and effectiveness of omidubicel based on a randomized, multicenter study comparing transplantation of omidubicel to transplantation of umbilical cord blood, in subjects between the ages of 12 and 65 years. [ 3 ] The study enrolled a total of 125 participants. [ 3 ] All participants in the study had confirmed blood cancers. [ 3 ] The efficacy of omidubicel was based on the amount of time needed for recovery of the participant's neutrophils (a type of white blood cell that helps protect the body from infections) and the incidence of infections following transplantation. [ 3 ] In total, 125 participants were randomized--62 participants to receive omidubicel-onlv and 63 to the unmanipulated cord blood group. [ 6 ] Fifty-two participants were transplanted with omidubicel-onlv receiving a median CD34+ cell dose of 9.0 X 106 cells/kg (range 2.1 – 47.6 X 106 cells/kg). [ 6 ] Fifty-six participants were transplanted in the unmanipulated cord blood arm with one or two cord units (66% received two cord units). [ 6 ] In the 42 participants with reported post-thaw cell dose, the median CD34+ cell dose was 0.2 X 106 cells/kg (range 0.0 – 0.8 X 106 cells/kg). Multiple conditioning regimens were used, including total body irradiation-based or chemotherapy-based options. [ 6 ]
The FDA granted the application for omidubicel priority review , breakthrough therapy , and orphan drug designations. [ 3 ] [ 6 ] The FDA granted regular approval of Omisirge to Gamida Cell Ltd. [ 3 ] | https://en.wikipedia.org/wiki/Omidubicel |
Omni-Path Architecture ( OPA ) is a high-performance communication architecture developed by Intel . It aims for low communication latency , low power consumption and a high throughput . It directly competes with InfiniBand . Intel planned to develop technology based on this architecture for exascale computing . [ 1 ] [ 2 ] [ 3 ] The current owner of Omni-Path is Cornelis Networks.
Production of Omni-Path products started in 2015 and delivery of these products started in the first quarter of 2016. In November 2015, adapters based on the 2-port "Wolf River" ASIC [ 4 ] were announced, using QSFP28 connectors with channel speeds up to 100 Gbit/s. Simultaneously, switches based on the 48-port "Prairie River" ASIC were announced. [ 5 ] First models of that series were available starting in 2015. [ 6 ]
In April 2016, implementation of the InfiniBand "verbs" interface for the Omni-Path fabric was discussed. [ 7 ]
In October 2016, IBM , Hewlett Packard Enterprise , Dell , Lenovo , Samsung , Seagate Technology , Micron Technology , Western Digital and SK Hynix announced a joint consortium called Gen-Z to develop an open specification and architecture for non-volatile storage and memory products—including Intel's 3D Xpoint technology—which might in part compete against Omni-Path. [ 8 ] Intel offered their Omni-Path products and components via other (hardware) vendors. For example, Dell EMC offered Intel Omni-Path as Dell Networking H-series , following the naming-standard of Dell Networking in 2017. [ 9 ]
In July 2019, Intel announced it would not continue development of Omni-Path networks and canceled OPA 200 series (200-Gbps variant of Omni-Path). [ 10 ] [ 11 ]
In September 2020, Intel announced that the Omni-Path network products and technology would be spun out into a new venture with Cornelis Networks. Intel would continue to maintain support for legacy Omni-Path products, while Cornelis Networks continues the product line, leveraging existing Intel intellectual property related to Omni-Path architecture. [ 12 ] [ 13 ] [ 14 ]
In 2021, Cornelis announced Omni-Path Express, which replaces PSM2-based drivers and middleware, which trace back to PathScale 's PSM created in 2003, for the existing Omni-Path hardware, with a native libfabric provider. [ 15 ] [ 16 ] | https://en.wikipedia.org/wiki/Omni-Path |
OmniGraphSketcher was a software application from The Omni Group for creating quantitative diagrams . It allowed users to plot data and draw freehand curves, filled areas, and text labels on a coordinate plane . It was available from March 2009 through July 2013.
OmniGraphSketcher had its origins in Graph Sketcher , a Mac OS X application created by Robin Stewart that was first commercially released in 2006. [ 1 ] [ 2 ] The software was influenced by Stewart's academic research integrating data plotting with freehand illustration user interfaces . [ 3 ] [ 4 ]
The Omni Group acquired Graph Sketcher in 2008 and launched OmniGraphSketcher for Mac in March 2009, [ 5 ] [ 6 ] followed by an iPad version in April 2010. [ 7 ]
In July 2013, the Omni Group discontinued OmniGraphSketcher, and in January 2014 released its source code under an open-source license as GraphSketcher . [ 8 ] [ 9 ]
Outlets such as Macworld , MacUser , and MacNN described OmniGraphSketcher as "one of those programs that does one thing and does it very well." [ 10 ] Most rated it 4/5, appreciating the simplicity of making graphs but noting some limitations and interface glitches with the iPad version. [ 11 ] [ 12 ] [ 13 ]
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OmniGraphSketcher |
OmniPage is an optical character recognition (OCR) application available from Kofax Incorporated.
OmniPage was one of the first OCR programs to run on personal computers. [ 1 ] It was developed in the late 1980s and sold by Caere Corporation, a company headed by Robert Noyce . The original developers were Philip Bernzott, John Dilworth, David George, Bryan Higgins, and Jeremy Knight. [ 2 ] [ 3 ] [ 4 ] Caere was acquired by ScanSoft in 2000. [ 5 ] ScanSoft acquired Nuance Communications in 2005, and took over its name. [ 6 ] By 2019 OmniPage had been sold to Kofax Inc. [ 7 ]
OmniPage supports more than 120 different languages. [ 8 ] OmniPage provides software development kits for integrating OCR functionality into other applications, such as Microsoft Office Document Imaging and UiPath. [ 9 ] [ 10 ]
This software article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OmniPage |
OmniSTAR is a satellite-based augmentation system ( SBAS ) service provider. OmniSTAR correction signals are proprietary, and a subscription must be bought from the OmniSTAR corporation to receive a subscription authorization. [ 1 ] OmniSTAR uses geostationary satellites in eight regions covering most of the landmass of each inhabited continent on Earth:
MSV service is provided by the MSAT AMSC-1 and MSAT-M1 satellites, operated by a company called Mobile Satellite Ventures .
To access the OmniSTAR solution the user must have an OmniSTAR-capable receiver. OmniSTAR capable receivers are available from a number of GPS manufacturers such as Autofarm, Geneq, Hemisphere GPS , NovAtel, Topcon, Trimble, and Raven.
The OmniSTAR service options include both single-frequency (L1 only) code phase DGPS solutions and dual-frequency (L1/L2) carrier phase solutions. Accuracy depends on satellite geometry, local conditions, receiver capability and other variables, but typically the L1-only solution (VBS - Virtual Base Station) yields horizontal accuracy of < +/1 meter > 95% of the time and the L1/L2 solutions (OmniSTAR HP, OmniSTAR XP or HP/XP combined) provide horizontal accuracies of < +/- 15 cm > 95% of the time.
XP makes use of precise orbit and clock corrections of the GPS Satellites. The data is bought from Nasa JPL
G2 uses Orbit and Clocks calculated from Omnistar's own network of reference stations.
Motorola has an optical headend product line that once owned the Omnistar name.
This technology-related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OmniSTAR |
Omni processor is a term coined in 2012 by staff of the Water, Sanitation, Hygiene Program of the Bill & Melinda Gates Foundation [ 1 ] to describe a range of physical, biological or chemical treatments to remove pathogens from human-generated fecal sludge , while simultaneously creating commercially valuable byproducts (e.g., energy). Air from feces are separated from common air, then these collected air from feces are compressed like (LPG) and used as fuel. An omni processor mitigates unsafe methods in developing countries of capturing and treating human waste, which annually result in the spread of disease and the deaths of more than 1.5 million children.
Rather than a trademark, or a reference to a specific technology, the term omni processor is a general term for a range of self-sustaining, independently developed systems designed with the same end in mind, to transform and extract value from human waste — using various technological approaches, including combustion , supercritical water oxidation and pyrolysis .
In the term, omni refers to the ability of an omni processor to treat a wide variety of waste streams or fuel sources.
Since 2012, the Bill and Melinda Gates Foundation has been funding research into omni processors. An omni processor is any of various types of technologies that treat fecal sludge, also known as septage to remove pathogens and simultaneously extract byproducts with commercial value, for example energy or soil nutrients, [ 1 ] the latter which could be reused in agriculture. The omni processor program, which targets community-scale solutions that may optionally combine sludge and solid waste processing, complements the foundation's pit latrine emptying ("omni-ingestor") and "Reinvent the Toilet" programs.
The omni processor is targeted as a solution for developing countries , although challenges around technical and financial aspects remain. [ 2 ] Omni processors and omni ingestors are being designed to provide an alternative to sewerage system-based technologies. They are also intended to address the large number of existing pit latrines which lack a supporting infrastructure of fecal sludge collection and processing when the pits are full. Sludge from pit latrines has to be removed from the pits for treatment and disposal either by pumping (if the fecal sludge is sufficiently liquid) or by manual emptying with shovels or other devices (in India, this practice is called manual scavenging ). Despite new low-cost pumps being developed, only a small fraction of sludge is safely extracted and treated currently in many African and Asian cities. [ 2 ] [ 3 ]
Biomass Controls PBC is a U.S. Delaware public benefit corporation that delivered the first biogenic refinery (OP) prototype to New Delhi, India , in 2014 in partnership with the Climate Foundation. This system was designed to process non-sewered sanitation for populations between 100 and 10,000 people. The prototype was funded by the Bill and Melinda Gates Foundation. In 2016 a biogenic refinery was delivered to Kivalina, Alaska , for the processing of urine-diverting dry toilets (UDDTs) as part of the Alaska Water & Sewer Challenge. [ 4 ] In 2017, three systems were shipped to India and installed in the cities of Wai , Warangal and Narsapur in partnership with Tide Technocrats. In 2018 a prototype was shown that can generate electricity ( mCHP ) from the thermal energy from the processing of fecal sludge, at the Bill and Melinda Gates Foundation reinvented toilet event in Beijing, China . [ 5 ] In 2019, a system was set up at a dairy farm to process the separated solids from cow manure. This system demonstrated a significant reduction in greenhouse gas emissions while reducing solids volume by over 90% and producing biochar .
The U.S.-based company Sedron Technologies (formerly Janicki Bioenergy) presented in 2014 a prototype using combustion . Their process is a sewage sludge treatment system that produces drinking water and electrical energy as end products from sewage sludge . [ 6 ] Manufactured by Sedron Technologies, the proof of concept model was funded by the Bill and Melinda Gates Foundation. The S100 prototype model can produce 10,800 liters of drinking water per day and 100 kW net electricity. A larger model under development, the S200, is designed to handle the waste from 100,000 people, produce 86,000 liters of drinking water per day and 250 kW net output electricity. These systems are designed to provide a "self-sustaining bioenergy " process. [ 7 ] [ 8 ]
The treatment process first involves boiling (or thermally drying) the sewage sludge, during which water vapor is boiled off and recovered. A dry sludge is left behind which is then combusted as fuel to heat a boiler. This boiler produces steam and the heat necessary for the boiling process. The steam is then used to generate electrical energy. Some of this electrical energy is used for the final water reverse osmosis purification stages to produce safe drinking water, and to power ancillary pumps, fans and motors. The process immediately uses the solid fuel it produces, and therefore the process does not make a solid fuel product as an end product.
A pilot project of Sedron Technologies' omni processor was installed in Dakar , Senegal, in 2015 and can now treat the fecal sludge of 50,000-100,000 people. [ 9 ]
The U.S.-based NGO Climate Foundation, in collaboration with Stanford University, has built several pilot-scale reactors to treat human waste and turn it into biochar, which can be used as an agricultural soil amendment. [ 10 ]
Scientists at Duke University in the U.S. have developed and are testing a pilot fecal sludge treatment unit that fits in a 20-foot shipping container and treats the fecal matter of roughly 1000 people using a new supercritical water oxidation (SCWO) process. [ 11 ] The SCWO technology can covert any type of organic waste (fecal, food waste, paper, plastic, etc.) to energy and clean water. [ 12 ]
The waste (sludge) is reacted with air at temperatures and pressures above the critical point of water (374 °C, 221 Bar) to convert all of the organics into clean water and CO 2 in seconds. Byproducts include distilled water, clean water which contains suspended inorganic minerals that can be utilized as fertilizers. The unit generates more than 900 liters of water for each ton of processed waste and the water can be processed further to drinking water.
The continuous process utilizes the energy embedded in the waste, thus enabling operating off-the-grid. 374Water is a Duke University spin-off company aiming to commercialize the SCWO technology. [ 13 ]
Unilever PLC in the United Kingdom is developing a pyrolysis -based fecal sludge treatment unit designed to serve over 2000 people. [ 14 ]
The omni processor initiative for processing fecal sludge is being complemented by an effort to develop new technologies for improved pit latrine emptying (called by the Gates Foundation the "omni ingestor" [ 15 ] ) and by the Reinvent the Toilet Challenge. The latter is a long-term research and development effort to develop a hygienic, stand-alone toilet. It is focused on "reinventing the flush toilet ". The aim is to create a toilet that not only removes pathogens from human excreta, but also recovers resources such as energy, clean water, and nutrients (a concept also known as reuse of excreta ). It should operate "off the grid" without connections to water, sewer, or electrical networks. Finally, it should cost less than 5 US-cents per user per day. [ 16 ]
In a publicity stunt in late 2014, Bill Gates drank the water produced from Sedron Technologies' omni processor system, causing widespread media attention. [ 7 ] In early 2015, Gates appeared on Late Night With Jimmy Fallon and challenged Fallon to see if he could taste the difference between water from this particular "omni processor" or bottled water . [ 17 ]
The project was covered in a Netflix documentary mini-series Inside Bill's Brain: Decoding Bill Gates . | https://en.wikipedia.org/wiki/Omni_processor |
Omnicare, Inc. is an American company working in the health-care industry. It was established in April 1981 as a spinoff of healthcare businesses from Chemed and W. R. Grace and Company . It is currently a pharmacy specializing in nursing homes. [ 1 ] In 2015, Omnicare was acquired by CVS Health . [ 2 ]
In 2012, the Federal Trade Commission (FTC) sued Omnicare to block its hostile takeover of its rival PharMerica under federal anti-trust law . The FTC alleged that the acquisition would boost drug costs and inflate Medicare expenditures by consolidating the industry and reducing price competition. [ 3 ] PharMerica owned 97 long-term-care pharmacies, while Omnicare owned approximately 200. The merger would have given Omnicare a 57% market share versus two percent for its nearest, non-PharMerica rival. [ 4 ] Because of the FTC opposition, the takeover was terminated.
In November 2009, Omnicare paid US$ 98,000,000 to the federal government to settle five " qui tam " ( whistleblower ) lawsuits and government charges that the company had paid or solicited a variety of kickbacks . [ 5 ] The company admitted no wrongdoing. [ 6 ] The charges included allegations that Omnicare solicited and received kickbacks from a pharmaceutical manufacturer Johnson & Johnson , in exchange for agreeing to recommend that physicians prescribe Risperdal, a Johnson & Johnson antipsychotic drug, to nursing home patients. [ citation needed ]
Starting in 2006, healthcare entrepreneur Adam B. Resnick sued Omnicare, a major supplier of drugs to nursing homes , under the False Claims Act , as well as the parties to the company's illegal kickback schemes. Omnicare allegedly paid kickbacks to nursing home operators to secure business, which constitutes Medicare and Medicaid fraud . Omnicare allegedly had paid $50 million to the owners (Leonard Grunstein and Rubin Schron ) of the Mariner Health Care Inc. and SavaSeniorCare Administrative Services LLC nursing home chains in exchange for the right to continue providing pharmacy services to the nursing homes. [ 7 ]
In 2010, Omnicare settled Resnick's False Claims Act suit that had been taken up by the U.S. Department of Justice by paying $19.8 million to the federal government, while Mariner and SavaSeniorCare settled for $14 million. [ 8 ] [ 9 ]
A second whistleblower lawsuit filed against Omnicare by Resnick and Total Pharmacy Services V.P. Maureen Nehls related to kickbacks that had been part of its 2004 acquisition of Total Pharmacy Services was settled (circa 2013) for $17.2 million by Omnicare and $5 million by the Total Pharmacy owners. Reportedly Omnicare was set to acquire JobMinglr.com for an undisclosed sum. [ 10 ] | https://en.wikipedia.org/wiki/Omnicare |
Omnishale process (also known as the Petro Probe process ) is an in situ shale oil extraction technology to convert kerogen in oil shale to shale oil . This process is classified as an externally generated hot gas technology. The technology is developed by General Synfuels International, a subsidiary of Earth Search Sciences. [ 1 ]
The Omnishale shale oil extraction in situ technology was invented by Ron McQueen and developed and tested by Petro Probe and General Synfuels International. On 11 October 2005, a subsidiary of Earth Search Sciences Petro Probe acquired an unlimited license to use Omnishale shale oil extraction technology developed by General Synfuels International, Inc. On 15 August 2008, Earth Search Sciences acquired General Synfuels International and oil shale activities of Petro Probe were transferred to General Synfuels International. In 2009, General Synfuels International started a cooperation with Anadarko Petroleum . [ 2 ] On 30 March 2010, General Synfuels International started construction of the test plant on the Anadarko-controlled test site near Rock Springs, Wyoming , in the Green River Formation . [ 3 ] In April 2010, a $10 million Patriot's Oil Shale Technology Fund L.P. was formed to complete funding of the Phase 1 construction of the test shale oil plant. [ 4 ]
The Omnishale shale oil extraction in situ technology of Earth Search Sciences was invented by Ron McQueen and developed by Petro Probe and General Synfuels International. In this process, holes are drilled into the oil shale formation and a processing inlet conduit is placed within holes. Pressurized air super heated by an above-ground combustor is directed into the oil shale formation through the inlet conduit. As a result, the kerogen in oil shale is heated and converted to a gaseous state. [ 4 ] [ 5 ] [ 6 ] | https://en.wikipedia.org/wiki/Omnishale_process |
On-board diagnostics ( OBD ) is a term referring to a vehicle's self-diagnostic and reporting capability. In the United States, this capability is a requirement to comply with federal emissions standards to detect failures that may increase the vehicle tailpipe emissions to more than 150% of the standard to which it was originally certified. [ 1 ] [ 2 ]
OBD systems give the vehicle owner or repair technician access to the status of the various vehicle sub-systems. The amount of diagnostic information available via OBD has varied widely since its introduction in the early 1980s versions of onboard vehicle computers. Early versions of OBD would simply illuminate a tell-tale light if a problem was detected, but would not provide any information as to the nature of the problem. Modern OBD implementations use a standardized digital communications port to provide real-time data and diagnostic trouble codes which allow malfunctions within the vehicle to be rapidly identified.
GM's ALDL (Assembly Line Diagnostic Link) is sometimes referred to as a predecessor to, or a manufacturer's proprietary version of, an OBD-I diagnostic starting in 1981. This interface was made in different varieties and changed with power train control modules (aka PCM, ECM, ECU). Different versions had slight differences in pin-outs and baud rates. Earlier versions used a 160 baud rate, while later versions went up to 8192 baud and used bi-directional communications to the PCM. [ 15 ] [ 16 ]
The regulatory intent of OBD-I was to encourage auto manufacturers to design reliable emission control systems that remain effective for the vehicle's "useful life". [ 17 ] The hope was that by forcing annual emissions testing for California starting in 1988, [ 18 ] and denying registration to vehicles that did not pass, drivers would tend to purchase vehicles that would more reliably pass the test. OBD-I was largely unsuccessful, as the means of reporting emissions-specific diagnostic information was not standardized. Technical difficulties with obtaining standardized and reliable emissions information from all vehicles led to an inability to implement the annual testing program effectively. [ 19 ]
The Diagnostic Trouble Codes (DTC's) of OBD-I vehicles can usually be found without an expensive scan tool. Each manufacturer used their own Diagnostic Link Connector (DLC), DLC location, DTC definitions, and procedure to read the DTC's from the vehicle. DTC's from OBD-I cars are often read through the blinking patterns of the 'Check Engine Light' (CEL) or 'Service Engine Soon' (SES) light. By connecting certain pins of the diagnostic connector, the 'Check Engine' light will blink out a two-digit number that corresponds to a specific error condition. The DTC's of some OBD-I cars are interpreted in different ways, however. Cadillac fuel-injected vehicles are equipped with actual onboard diagnostics, providing trouble codes, actuator tests and sensor data through the new digital Electronic Climate Control display.
Holding down 'Off' and 'Warmer' for several seconds activates the diagnostic mode without the need for an external scan tool. Some Honda engine computers are equipped with LEDs that light up in a specific pattern to indicate the DTC. General Motors, some 1989–1995 Ford vehicles (DCL), and some 1989–1995 Toyota/Lexus vehicles have a live sensor data stream available; however, many other OBD-I equipped vehicles do not. OBD-I vehicles have fewer DTC's available than OBD-II equipped vehicles.
OBD 1.5 refers to a partial implementation of OBD-II which General Motors used on some vehicles in 1994, 1995 & 1996 (GM did not use the term OBD 1.5 in the documentation for these vehicles — they simply had an OBD and an OBD-II section in the service manual).
For example, the 1994–1995 model year Corvettes have one post-catalyst oxygen sensor (although they have two catalytic converters ), and have a subset of the OBD-II codes implemented. [ 20 ]
This hybrid system was present on GM B-body cars (the Chevrolet Caprice, Impala, and Buick Roadmaster) for 1994–1995 model years, H-body cars for 1994–1995, W-body cars (Buick Regal, Chevrolet Lumina) for 1995 only, Chevrolet Monte Carlo (1995 only), Pontiac Grand Prix, Oldsmobile Cutlass Supreme (for 1994–1995), L-body (Chevrolet Beretta/Corsica) for 1994–1995, Y-body (Chevrolet Corvette) for 1994–1995, on the F-body (Chevrolet Camaro and Pontiac Firebird) for 1995 and on the J-Body (Chevrolet Cavalier and Pontiac Sunfire) and N-Body (Buick Skylark, Oldsmobile Achieva, Pontiac Grand Am) for 1995 and 1996 and also for North American delivered 1994–1995 Saab vehicles with the naturally aspirated 2.3.
The pinout for the ALDL connection on these cars is as follows:
For ALDL connections, pin 9 is the data stream, pins 4 and 5 are ground, and pin 16 is the battery voltage.
An OBD 1.5 compatible scan tool is required to read codes generated by OBD 1.5.
Additional vehicle-specific diagnostic and control circuits are also available on this connector. For instance, on the Corvette there are interfaces for the Class 2 serial data stream from the PCM, the CCM diagnostic terminal, the radio data stream, the airbag system, the selective ride control system, the low tire pressure warning system, and the passive keyless entry system. [ 21 ]
An OBD 1.5 has also been used in the Ford Scorpio since 95. [ 22 ]
OBD-II is an improvement over OBD-I in both capability and standardization. The OBD-II standard specifies the type of diagnostic connector and its pinout, the electrical signalling protocols available, and the messaging format. It also provides a candidate list of vehicle parameters to monitor along with how to encode the data for each. There is a pin in the connector that provides power for the scan tool from the vehicle battery, which eliminates the need to connect a scan tool to a power source separately. However, some technicians might still connect the scan tool to an auxiliary power source to protect data in the unusual event that a vehicle experiences a loss of electrical power due to a malfunction. Finally, the OBD-II standard provides an extensible list of DTCs. As a result of this standardization, a single device can query the on-board computer(s) in any vehicle. This OBD-II came in two models OBD-IIA and OBD-IIB. OBD-II standardization was prompted by emissions requirements, and though only emission-related codes and data are required to be transmitted through it, most manufacturers have made the OBD-II Data Link Connector the only one in the vehicle through which all systems are diagnosed and programmed. OBD-II Diagnostic Trouble Codes are 4-digit, preceded by a letter: P for powertrain (engine and transmission), B for body, C for chassis, and U for network.
The OBD-II specification provides for a standardized hardware interface — the female 16-pin (2x8) J1962 connector , where type A is used for 12-volt vehicles and type B for 24-volt vehicles. Unlike the OBD-I connector, which was sometimes found under the bonnet of the vehicle, the OBD-II connector is required to be within 2 feet (0.61 m) of the steering wheel (unless an exemption is applied for by the manufacturer, in which case it is still somewhere within reach of the driver).
SAE J1962 defines the pinout of the connector as:
GM: J2411 GMLAN/SWC/Single-Wire CAN. Audi: Switched +12 to tell a scan tool whether the ignition is on. VW: Switched +12 to tell a scan tool whether the ignition is on. Mercedes [ 23 ] (K-Line): Ignition control (EZS), air-conditioner (KLA), PTS, safety systems (Airbag, SRS, AB) and some other.
GM: 8192 baud ALDL where fitted. BMW: RPM signal. Toyota: RPM signal. Mercedes (K-Line): ABS, ASR, ESP, ETS, BAS diagnostic.
SAE J1850 PWM and VPW
SAE J1850 PWM only (not SAE 1850 VPW)
Ethernet TX+ (Diagnostics over IP) Ford DCL(+) Argentina, Brazil (pre OBD-II) 1997–2000, USA, Europe, etc. Chrysler CCD Bus(+) Mercedes (TNA): TD engine rotation speed.
Ethernet TX- (Diagnostics over IP) Ford DCL(-) Argentina, Brazil (pre OBD-II) 1997–2000, USA, Europe, etc. Chrysler CCD Bus(-) Mercedes (K-Line): Gearbox and other transmission components (EGS, ETC, FTC).
Ethernet RX+ (Diagnostics over IP) Mercedes (K-Line): All activity module (AAM), Radio (RD), ICS (and more)
Ethernet RX- (Diagnostics over IP) Ford: FEPS – Programming PCM voltage Mercedes (K-Line): AB diagnostic – safety systems.
(ISO 15765-4 and SAE J2284)
(ISO 15765-4 and SAE J2284)
(ISO 9141-2 and ISO 14230-4)
(ISO 9141-2 and ISO 14230-4)
Activate Ethernet (Diagnostics over IP) Many BMWs: A second K-line for non OBD-II (Body/Chassis/Infotainment) systems. Mercedes: Ignition
(+12 Volt for type A connector) (+24 Volt for type B connector)
The assignment of unspecified pins is left to the vehicle manufacturer's discretion. [ 24 ]
The European on-board diagnostics (EOBD) regulations are the European equivalent of OBD-II, and apply to all passenger cars of category M1 (with no more than 8 passenger seats and a Gross Vehicle Weight rating of 2,500 kg, 5,500 lb or less) first registered within EU member states since January 1, 2001 for petrol -engined cars and since January 1, 2004 for diesel engined cars. [ 25 ]
For newly introduced models, the regulation dates applied a year earlier – January 1, 2000 for petrol and January 1, 2003, for diesel. For passenger cars with a Gross Vehicle Weight rating of greater than 2500 kg and for light commercial vehicles, the regulation dates applied from January 1, 2002, for petrol models, and January 1, 2007, for diesel models.
The technical implementation of EOBD is essentially the same as OBD-II, with the same SAE J1962 diagnostic link connector and signal protocols being used.
With Euro V and Euro VI emission standards, EOBD emission thresholds are lower than previous Euro III and IV.
Each of the EOBD fault codes consists of five characters: a letter, followed by four numbers. [ 26 ] The letter refers to the system being interrogated e.g. Pxxxx would refer to the powertrain system. The next character would be a 0 if complies to the EOBD standard. So it should look like P0xxx.
The next character would refer to the sub system.
The following two characters would refer to the individual fault within each subsystem. [ 27 ]
The term "EOBD2" is marketing speak used by some vehicle manufacturers to refer to manufacturer-specific features that are not actually part of the OBD or EOBD standard. In this case "E" stands for Enhanced.
JOBD is a version of OBD-II for vehicles sold in Japan.
The ADR 79/01 Vehicle Standard ( A ustralian D esign R ule 79/01 – Emission Control for Light Vehicles, 2005) is the Australian equivalent of OBD-II. It applies to all vehicles of category M1 and N1 with a Gross Vehicle Weight rating of 3,500 kg (7,700 lb) or less, registered from new within Australia and produced since January 1, 2006 for petrol -engined cars and since January 1, 2007 for diesel -engined cars. [ 28 ]
For newly introduced models, the regulation dates applied a year earlier – January 1, 2005 for petrol and January 1, 2006, for diesel. The ADR 79/01 standard was supplemented by the ADR 79/02 standard which imposed tighter emissions restrictions, applicable to all vehicles of class M1 and N1 with a Gross Vehicle Weight rating of 3500 kg or less, from July 1, 2008, for new models, July 1, 2010, for all models. [ 29 ]
The technical implementation of this standard is essentially the same as OBD-II, with the same SAE J1962 diagnostic link connector and signal protocols being used.
In North America, EMD and EMD+ are on-board diagnostic systems that were used on vehicles with a gross vehicle weight rating of 14,000 lb (6,400 kg) or more between the 2007 and 2012 model years if those vehicles did not already implement OBD-II. EMD was used on California emissions vehicles between model years 2007 and 2009 that did not already have OBD-II. EMD was required to monitor fuel delivery, exhaust gas recirculation, the diesel particulate filter (on diesel engines), and emissions-related powertrain control module inputs and outputs for circuit continuity, data rationality, and output functionality. EMD+ was used on model year 2010-2012 California and Federal petrol-engined vehicles with a gross vehicle weight rating of over 14,000 lb (6,400 kg), it added the ability to monitor nitrogen oxide catalyst performance. EMD and EMD+ are similar to OBD-I in logic but use the same SAE J1962 data connector and CAN bus as OBD-II systems. [ 8 ]
Five signaling protocols are permitted with the OBD-II interface. Most vehicles implement only one of the protocols. It is often possible to deduce the protocol used based on which pins are present on the J1962 connector: [ 30 ]
All OBD-II pinouts use the same connector, but different pins are used with the exception of pin 4 (battery ground) and pin 16 (battery positive).
OBD-II provides access to data from the engine control unit (ECU) and offers a valuable source of information when troubleshooting problems inside a vehicle. The SAE J1979 standard defines a method for requesting various diagnostic data and a list of standard parameters that might be available from the ECU. The various available parameters are addressed by "parameter identification numbers" or PID s which are defined in J1979. For a list of basic PIDs, their definitions, and the formula to convert raw OBD-II output to meaningful diagnostic units, see OBD-II PIDs . Manufacturers are not required to implement all PIDs listed in J1979 and they are allowed to include proprietary PIDs that are not listed. The PID request and data retrieval system gives access to real time performance data as well as flagged DTCs. For a list of generic OBD-II DTCs suggested by the SAE, see Table of OBD-II Codes . Individual manufacturers often enhance the OBD-II code set with additional proprietary DTCs.
Here is a basic introduction to the OBD communication protocol according to ISO 15031. In SAE J1979 these "modes" were renamed to "services", starting in 2003.
Various tools are available that plug into the OBD connector to access OBD functions. These range from simple generic consumer level tools to highly sophisticated OEM dealership tools to vehicle telematic devices.
A range of rugged hand-held scan tools is available.
Mobile device applications allow mobile devices such as cell phones and tablets to display and manipulate the OBD-II data accessed via USB adaptor cables or Bluetooth adapters plugged into the car's OBD II connector. Newer devices on the market are equipped with GPS sensors and the ability to transmit vehicle location and diagnostics data over a cellular network. Modern OBD-II devices can therefore nowadays be used to for example locate vehicles, monitor driving behavior in addition to reading Diagnostics Trouble Codes (DTC). Even more advanced devices allow users to reset engine DTC codes, effectively turning off engine lights in the dashboard; however, resetting the codes does not address the underlying issues and can in worst-case scenarios even lead to engine breakage where the source issue is serious and left unattended for long periods. [ 36 ] [ 37 ]
An OBD-II software package when installed in a computer ( Windows , Mac , or Linux ) can help diagnose the onboard system, read and erase DTCs, turn off MIL, show real-time data, and measure vehicle fuel economy. [ 38 ]
To use OBD-II software, one needs to have an OBD-II adapter (commonly using Bluetooth , Wi-Fi or USB ) [ 39 ] plugged in the OBD-II port to enable the vehicle to connect with the computer where the software is installed. [ 40 ]
A PC-based OBD analysis tool that converts the OBD-II signals to serial data (USB or serial port) standard to PCs or Macs. The software then decodes the received data to a visual display. Many popular interfaces are based on the ELM327 or STN [ 41 ] OBD Interpreter ICs, both of which read all five generic OBD-II protocols. Some adapters now use the J2534 API allowing them to access OBD-II Protocols for both cars and trucks.
In addition to the functions of a hand-held scan tool, the PC-based tools generally offer:
The extent that a PC tool may access manufacturer or vehicle-specific ECU diagnostics varies between software products [ 42 ] as it does between hand-held scanners.
Data loggers are designed to capture vehicle data while the vehicle is in normal operation, for later analysis.
Data logging uses include:
Analysis of vehicle black box data may be performed periodically, automatically transmitted wirelessly to a third party or retrieved for forensic analysis after an event such as an accident, traffic infringement or mechanical fault.
In the United States, many states now use OBD-II testing instead of tailpipe testing in OBD-II compliant vehicles (1996 and newer). Since OBD-II stores trouble codes for emissions equipment, the testing computer can query the vehicle's onboard computer and verify there are no emission related trouble codes and that the vehicle is in compliance with emission standards for the model year it was manufactured.
In the Netherlands, 2006 and later vehicles get a yearly EOBD emission check. [ 45 ]
Driver's supplementary vehicle instrumentation is instrumentation installed in a vehicle in addition to that provided by the vehicle manufacturer and intended for display to the driver during normal operation. This is opposed to scanners used primarily for active fault diagnosis, tuning, or hidden data logging.
Auto enthusiasts have traditionally installed additional gauges such as manifold vacuum, battery current etc. The OBD standard interface has enabled a new generation of enthusiast instrumentation accessing the full range of vehicle data used for diagnostics, and derived data such as instantaneous fuel economy.
Instrumentation may take the form of dedicated trip computers , [ 46 ] carputer or interfaces to PDAs , [ 47 ] smartphones, or a Garmin navigation unit.
As a carputer is essentially a PC, the same software could be loaded as for PC-based scan tools and vice versa, so the distinction is only in the reason for use of the software.
These enthusiast systems may also include some functionality similar to the other scan tools.
OBD II information is commonly used by vehicle telematics devices that perform fleet tracking, monitor fuel efficiency, prevent unsafe driving, as well as for remote diagnostics and by pay-as-you-drive insurance.
Although originally not intended for the above purposes, commonly supported OBD II data such as vehicle speed, RPM, and fuel level allow GPS-based fleet tracking devices to monitor vehicle idling times, speeding, and over-revving. By monitoring OBD II DTCs a company can know immediately if one of its vehicles has an engine problem and by interpreting the code the nature of the problem. It can be used to detect reckless driving in real time based on the sensor data provided through the OBD port. [ 48 ] This detection is done by adding a complex events processor (CEP) to the backend and on the client's interface. OBD II is also monitored to block mobile phones when driving and to record trip data for insurance purposes. [ 49 ]
OBD-II diagnostic trouble codes ( DTCs ) [ 50 ] [ 51 ] are five characters long, with the first letter indicating a category, and the remaining four being a hexadecimal number. [ 52 ]
The first character, representing category can only be one of the following four letters, given here with their associated meanings. (This restriction in number is due to how only two bits of memory are used to indicate the category when DTCs are stored and transmitted). [ 52 ]
The second character is a number in the range of 0–3. (This restriction is again due to memory storage limitations). [ 52 ]
The third character may denote a particular vehicle system that the fault relates to. [ 50 ]
Finally the fourth and fifth characters define the exact problem detected.
Researchers at the University of Washington and University of California examined the security around OBD and found that they were able to gain control over many vehicle components via the interface. Furthermore, they were able to upload new firmware into the engine control units . Their conclusion is that vehicle embedded systems are not designed with security in mind. [ 53 ] [ 54 ] [ 55 ]
There have been reports of thieves using specialist OBD reprogramming devices to enable them to steal cars without the use of a key. [ 56 ] The primary causes of this vulnerability lie in the tendency for vehicle manufacturers to extend the bus for purposes other than those for which it was designed, and the lack of authentication and authorization in the OBD specifications, which instead rely largely on security through obscurity . [ 57 ] | https://en.wikipedia.org/wiki/On-board_diagnostics |
On-water reactions are a group of organic reactions that take place as an emulsion in water and have an unusual reaction rate acceleration compared with (i) the same reaction in an organic solvent , or (ii) the corresponding dry media reaction . [ 1 ] This effect has been known for many years [ 2 ] but in 2005 researchers in the group of K. Barry Sharpless published a systematic study into this phenomenon. [ 3 ] [ 4 ]
The rate acceleration is found in certain Claisen rearrangements . In one typical example of this reaction at room temperature the chemical yield was found to be 100% on water after 120 h compared with 16% for the same reaction in toluene and 73% in the neat reaction.
Enhanced reactivity is also found in cycloadditions . The reaction of quadricyclane with DEAD is a 2σ + 2σ + 2π cycloaddition that on water takes place within 10 minutes at room temperature with 82% yield. The same reaction in toluene takes 24 hours at 80 °C with 70% yield. An emulsion reaction in fluorinated cyclohexane takes 36 hours and the neat reaction takes even longer (48 hours).
Other reactions with apolar reactants such as Ene reactions and Diels–Alder reactions also exhibit rate accelerations. An explanation is not available but it involves hydrogen bonding and the presence of a small amount of dissolved solute. This reaction type is of interest to green chemistry because it greatly reduces the usage of organic solvents, reaction product isolation is relatively easy, and it increases the yields and chemical purity with little extra expenditure, if not less.
In one study [ 5 ] a coupling reaction between an indole and a quinone takes place at room temperature without catalyst in water in 82% chemical yield even though reactants and products are insoluble in this medium. The reaction is much less efficient in homogeneous systems such as dichloromethane , toluene and acetonitrile or even the solvent free reaction or even the water reaction but now at 50°C.
The on water effect is also studied in cycloadditions of the type: [ 6 ]
In this reaction the alkyne methyl 2-octynoate reacts with triphenylphosphine to an intermediate zwitterionic allenolate , a dipolarophile for the 1,3-dipole 2-phenylnitrone . The primary regioselective [3+2] dipolar cycloaddition product then rearranges to a dihydroisoxazole with regeneration of the phosphine. This reaction only takes place in water with lithium chloride added even though the reactants do not dissolve in this medium. In organic solvents such as toluene or dichloromethane no reaction takes place.
An alternative classification with broader scope is suggested by Yujiro Hayashi [ 7 ] as he describes certain organocatalytic Aldol reactions as taking place in the presence of water . The observed effect in these reactions is not rate acceleration (that would be on water ), but an increase in enantioselectivity .
In the context of organocatalysis , both concepts of on-water reactions and in-the-presence-of-water reactions were criticized in 2007 as not so environmentally friendly by Donna Blackmond . According to Blackmond, separation of reaction product from the water phase usually requires organic solvent anyway, and in reported aqueous systems the water phase can in reality be less than 10% of the total reaction mixture with another component forming the actual solvent. Blackmond also notes that in reported instances, the observed rate-acceleration in presence of water is due to water suppressing reaction deactivation. [ 8 ] | https://en.wikipedia.org/wiki/On-water_reaction |
" Über formal unentscheidbare Sätze der Principia Mathematica und verwandter Systeme I " (" On Formally Undecidable Propositions of Principia Mathematica and Related Systems I ") is a paper in mathematical logic by Kurt Gödel . Submitted November 17, 1930, it was originally published in German in the 1931 volume of Monatshefte für Mathematik und Physik . Several English translations have appeared in print, and the paper has been included in two collections of classic mathematical logic papers. The paper contains Gödel's incompleteness theorems , now fundamental results in logic that have many implications for consistency proofs in mathematics. The paper is also known for introducing new techniques that Gödel invented to prove the incompleteness theorems.
The main results established are Gödel's first and second incompleteness theorems , which have had an enormous impact on the field of mathematical logic . These appear as theorems VI and XI, respectively, in the paper.
In order to prove these results, Gödel introduced a method now known as Gödel numbering . In this method, each sentence and formal proof in first-order arithmetic is assigned a particular natural number. Gödel shows that many properties of these proofs can be defined within any theory of arithmetic that is strong enough to define the primitive recursive functions . (The contemporary terminology for recursive functions and primitive recursive functions had not yet been established when the paper was published; Gödel used the word rekursiv ("recursive") for what are now known as primitive recursive functions.) The method of Gödel numbering has since become common in mathematical logic.
Because the method of Gödel numbering was novel, and to avoid any ambiguity, Gödel presented a list of 45 explicit formal definitions of primitive recursive functions and relations used to manipulate and test Gödel numbers. He used these to give an explicit definition of a formula Bew( x ) that is true if and only if x is the Gödel number of a sentence φ and there exists a natural number that is the Gödel number of a proof of φ . The name of this formula derives from Beweis , the German word for proof.
A second new technique invented by Gödel in this paper was the use of self-referential sentences. Gödel showed that the classical paradoxes of self-reference, such as " This statement is false ", can be recast as self-referential formal sentences of arithmetic. Informally,
the sentence employed to prove Gödel's first incompleteness theorem says "This statement is not provable." The fact that such self-reference can be expressed within arithmetic was not known until Gödel's paper appeared; independent work of Alfred Tarski on his indefinability theorem was conducted around the same time but not published until 1936.
In footnote 48a, Gödel stated that a planned second part of the paper would establish a link between consistency proofs and type theory (hence the "I" at the end of the paper's title, denoting the first part), but Gödel did not publish a second part of the paper before his death. His 1958 paper in Dialectica did, however, show how type theory can be used to give a consistency proof for arithmetic.
During his lifetime three English translations of Gödel's paper were printed, but the process was not without difficulty. The first English translation was by Bernard Meltzer ; it was published in 1963 as a standalone work by Basic Books and has since been reprinted by Dover and reprinted by Hawking ( God Created the Integers , Running Press, 2005:1097ff). The Meltzer version—described by Raymond Smullyan as a 'nice translation'—was adversely reviewed by Stefan Bauer-Mengelberg (1966). According to Dawson's biography of Gödel (Dawson 1997:216),
Fortunately, the Meltzer translation was soon supplanted by a better one prepared by Elliott Mendelson for Martin Davis 's anthology The Undecidable ; but it too was not brought to Gödel's attention until almost the last minute, and the new translation was still not wholly to his liking ... when informed that there was not time enough to consider substituting another text, he declared that Mendelson's translation was 'on the whole very good' and agreed to its publication. [Afterward he would regret his compliance, for the published volume was marred throughout by sloppy typography and numerous misprints.]
The translation by Elliott Mendelson appears in the collection The Undecidable (Davis 1965:5ff). This translation also received a harsh review by Bauer-Mengelberg (1966), who in addition to giving a detailed list of the typographical errors also described what he believed to be serious errors in the translation.
A translation by Jean van Heijenoort appears in the collection From Frege to Gödel: A Source Book in Mathematical Logic (van Heijenoort 1967). A review by Alonzo Church (1972) described this as "the most careful translation that has been made" but also gave some specific criticisms of it. Dawson (1997:216) notes:
The translation Gödel favored was that by Jean van Heijenoort ... In the preface to the volume van Heijenoort noted that Gödel was one of four authors who had personally read and approved the translations of his works.
This approval process was laborious. Gödel introduced changes to his text of 1931, and negotiations between the men were "protracted": "Privately van Heijenoort declared that Gödel was the most doggedly fastidious individual he had ever known." Between them they "exchanged a total of seventy letters and met twice in Gödel's office in order to resolve questions concerning subtleties in the meanings and usage of German and English words." (Dawson 1997:216-217).
Although not a translation of the original paper, a very useful 4th version exists that "cover[s] ground quite similar to that covered by Godel's original 1931 paper on undecidability" (Davis 1952:39), as well as Gödel's own extensions of and commentary on the topic. This appears as On Undecidable Propositions of Formal Mathematical Systems (Davis 1965:39ff) and represents the lectures as transcribed by Stephen Kleene and J. Barkley Rosser while Gödel delivered them at the Institute for Advanced Study in Princeton, New Jersey in 1934. Two pages of errata and additional corrections by Gödel were added by Davis to this version. This version is also notable because in it Gödel first describes the Herbrand suggestion that gave rise to the (general, i.e. Herbrand–Gödel) form of recursion . | https://en.wikipedia.org/wiki/On_Formally_Undecidable_Propositions_of_Principia_Mathematica_and_Related_Systems |
Onboard passenger information system (PIS) is an integrated system for supplying passengers of public transport with information on their current journey through audiovisual information. The systems are installed on-board of public transport vehicles and provide ambient information to passengers both inside and outside of the vehicles. This is in contrast to a station/wayside passenger information system providing information to passengers on the platforms. [ 1 ]
This system provides real-time information to passengers regarding various aspects of their journey, including schedules, station stops, route maps, safety instructions, and emergency procedures. [ 2 ] The passenger information system has two modes of conveying information: [ 3 ]
The on-board passenger information system provides relevant information throughout the journey allowing passengers to make informed decisions about their travel plans, including transfers, connections, and arrival times. [ 4 ]
PIS also enables the distribution of safety procedures.
The PIS streamlines public transport operations by disseminating information to passengers automatically. By reducing manual announcements and inquiries, the system frees up onboard staff to focus on other tasks.
PIS improves accessibility for passengers with disabilities or special needs by providing multi-channel information delivery, including audio announcements and visual displays, allowing passengers, regardless of their abilities, to access the information they need to navigate the journey independently. [ 5 ]
In the 20th century, onboard passenger information relied solely on manual announcements by on-board conductors and staff using an analog audio system. Passengers were verbally informed about upcoming stations, arrival times, and other relevant information. [ 6 ] [ 7 ]
Mechanical display boards such as flip-disc display were used as destination signs . Other static signage, such as stickers, folders, etc., provided visual communication of public transport schedules, vehicle numbers, and other information. [ 8 ]
The adoption of LED technology in the latter half of the 20th century modernized onboard communication in public transport. LED displays offered dynamic visual information and were energy-efficient for relaying real-time updates on station stop calling patterns and end destination information. Concurrently with the introduction of LED, digital audio systems began replacing traditional analog audio systems, offering clearer sound quality and the ability to broadcast pre-recorded messages. These systems enhanced accessibility for passengers because of the improved speech intelligibility of said digital audio systems.
The widespread adoption of Global Positioning System (GPS) technology in the 21st century enabled the integration of real-time location tracking into the on-board passenger information system. This allowed onboard systems to determine the train's position and inform passengers about upcoming stations. [ 9 ]
The introduction of TFT displays added more visualization to on-board passenger information systems allowing a more graphical representation of the information. It allowed passengers to rely on a wide range of information, including route maps, images, videos, infomercials from the public transport agency, etc.
The proliferation of wireless connectivity, including Wi-Fi and cellular networks, has further enhanced the capabilities of the Passenger Information System . Whereas before the introduction of wireless connectivity, the passenger information system could only rely on local information available on-board of the train, since the introduction of wireless connectivity, passengers can access real-time updates from the passenger information system, improving the overall travel experience.
Broadcasting of audio announcements through the speakers installed on-board of the vehicle. These announcements can be triggered by the automatic information system, providing auditory cues for passengers, including announcements of arrival in the next station, welcome messages, etc. The on-board crew can use specific handsets part of the audio announcement system to provide public address announcements to the passengers on top of the automatic information. Minimally consists of an amplifier, speakers, handsets (to perform public address).
Audio intercom system provides communication between the passengers and on-board staff. This allows for bidirectional communication between the on-board crew members (crew intercom) and the on-board crew members and passengers (passenger intercom). Minimally consists out of a handset (for crew interaction) and passenger communication units (for passenger interaction). [ 10 ]
Digital display screens inside the vehicle (to address passengers on-board) or outside the vehicle (to address passengers on the platform) displaying mainly textual information to passengers. They typically provide information on upcoming stations, end station, route number of the vehicle, etc. Compared to TFT displays, LED displays are better suited for use on the outside of the vehicle thanks to better contrast, higher readability with direct sunlight, etc.
Digital display screens inside the vehicle displaying textual and graphical information to passengers. They typically provide information on the current journey information (upcoming stations, arrival times, dynamic route maps, etc.) as well as infotainment information (advertisements, instruction videos, etc.) [ 11 ]
Installed in select (often locked) compartments of the vehicle and used by the driver/crew to control the Passenger Information System. Typical functionalities include starting the automatic announcements by entering a trip code, launching an ad-hoc pre-recorded announcement, consulting the current status of the PIS system, etc.
The central controller contains a software application that is responsible for driving the automatic information distribution across the different components of the onboard passenger information system.
Software application that runs off-board (often a Cloud-hosted solution) and that allows public transport operators to manage the PIS system in terms of configuration (e.g., changes to the PIS behavior), operational management (e.g., launching an ad-hoc announcement from the OCC and handle interactions with 3rd party systems (e.g., ITS for exchange of real-time information).
Audio
LED
TFT
Controller software
Passenger Information Systems in public transport have some inherent challenges linked to the different life cycles of the systems (mechanical – electronic – software) in place. Regarding the mechanical vehicle bodies, there are examples of trains that have a lifetime of 30+ years, while the typical lifetime of hardware/electronic systems is between 5–10 years. The expectations of passengers and public transit agencies in terms of the functionalities of the Passenger information systems are evolving on a much higher pace, which can only be realized by tackling them in software. One of the primary challenges in on-board passenger information systems is synchronizing the disparate lifecycles of mechanical, electronic and software components. Coordinating maintenance schedules and upgrade cycles across these domains is essential to prevent disruptions. [ 14 ] [ 15 ] | https://en.wikipedia.org/wiki/Onboard_passenger_information_system |
An oncoantigen is a surface or soluble tumor antigen that supports tumor growth. [ 1 ] A major problem of cancer immunotherapy is the selection of tumor cell variants that escape immune recognition. The notion of oncoantigen was set forth in the context of cancer immunoprevention to define a class of persistent tumor antigens not prone to escape from immune recognition. [ 2 ]
Localization of oncoantigens outside tumor cells allows recognition by antibodies if downregulation of class I major histocompatibility complex (MHC-I) molecules prevents T cell recognition. Most tumor antigens are intracellular proteins. Circulating antibodies do not penetrate inside cells, hence intracellular proteins are only recognized by T cells as MHC-I-bound antigenic peptides exposed on the surface of tumor cells. However downmodulation or complete loss of MHC-I expression occurs in most human tumors, [ 3 ] making them altogether invisible to the immune system of the host. When tumor cells downregulate MHC-I, only antigens expressed on the cell surface and/or secreted in the extracellular fluids can be recognized by antibodies.
Loss of oncoantigen expression is unlikely, because oncoantigens support tumor growth. Loss of tumor antigen expression is another cause of escape from immune recognition. This occurs because most tumor antigens are not essential for tumor growth. Hence loss of expression does not decrease the fitness of cancer cells. In contrast, downmodulation of molecules like oncogene products, which are essential for tumor growth, would impair tumor cells. The complete dependence (also called "addiction") of tumor growth from a given gene product can cease if further genetic alterations occur that activate alternative signaling pathways. Thus, the persistence of oncoantigens is not an absolute property, but rather a feature of specific stages of tumor development.
The prototypic oncoantigen is HER2/neu , a membrane tyrosine kinase similar to the epidermal growth factor receptor (EGFR, or HER-1), expressed in about one-fourth of breast cancers . Vaccines against HER2/neu were shown to prevent mammary carcinoma in HER2/neu transgenic mice [ 4 ] and are being tested for cancer therapy in humans. Monoclonal antibodies against HER-2 (e.g. trastuzumab ) are approved for therapy of human breast cancer . Other molecules fulfilling the definition of oncoantigen are EGFR/HER-1, the mucin MUC1 and the idiotype of B and T cell malignancies. [ 5 ] Further candidates are receptor tyrosine kinases and growth factors , but in most cases the induction of effective anti-tumor immune responses against such molecules remains to be demonstrated. Most tumor antigens are not oncoantigens, either because they are intracellular molecules, like cancer-testis antigen such as MAGE family members, or because they appear to be dispensable without significant alterations of tumorigenicity, like the carcinoembryonic antigen (CEA) or the prostate specific antigen (PSA).
Novel strategies will be required to identify new oncoantigens amenable to human application. [ 6 ]
Prevention of mouse mammary carcinoma with vaccines against HER2/neu led to the development of the oncoantigen concept, thanks to the addiction of transgenic tumors to HER-2 expression and to the fundamental role of vaccine-induced anti-HER-2 antibodies in the arrest of tumor development. Oncoantigens are thought to be the ideal target for immunologic prevention of cancer in individuals at risk, because the continuous generation of precancerous or early cancerous cells might easily lead over time to the emergence of antigen- or MHC-loss escape variants. As escape variants are a major cause of failure also in cancer immunotherapy , it is likely that targeting oncoantigens with vaccines or antibodies will have a stronger clinical impact than attempts at targeting other tumor antigens.
The problem so far in using vaccines in oncoantigen research is that the vaccines are typically not long lasting. This is because of the heterogeneous nature of cancer cells. Vaccinations may help the immune system locate certain oncoantigens such as MET , RET , CD20 and CD22 . However; cells that evade the immune system begin to populate and thus cause the growth of a more resistant tumor.
There is a use of oncoantigens as markers for faster diagnosis of cancer. The oncoantigens presented from cancerous cells can be used in genomics as biomarkers . This can help in faster and easier diagnosis of cancer. Oncoantigens may have a use in cancer research in the future through such advances. | https://en.wikipedia.org/wiki/Oncoantigen |
Oncogenomics is a sub-field of genomics that characterizes cancer -associated genes . It focuses on genomic, epigenomic and transcript alterations in cancer.
Cancer is a genetic disease caused by accumulation of DNA mutations and epigenetic alterations leading to unrestrained cell proliferation and neoplasm formation. The goal of oncogenomics is to identify new oncogenes or tumor suppressor genes that may provide new insights into cancer diagnosis, predicting clinical outcome of cancers and new targets for cancer therapies. The success of targeted cancer therapies such as Gleevec , Herceptin and Avastin raised the hope for oncogenomics to elucidate new targets for cancer treatment. [ 1 ]
Besides understanding the underlying genetic mechanisms that initiate or drive cancer progression, oncogenomics targets personalized cancer treatment. Cancer develops due to DNA mutations and epigenetic alterations that accumulate randomly. Identifying and targeting the mutations in an individual patient may lead to increased treatment efficacy.
The completion of the Human Genome Project facilitated the field of oncogenomics and increased the abilities of researchers to find oncogenes. Sequencing technologies and global methylation profiling techniques have been applied to the study of oncogenomics.
The genomics era began in the 1990s, with the generation of DNA sequences of many organisms. In the 21st century, the completion of the Human Genome Project enabled the study of functional genomics and examining tumor genomes. Cancer is a main focus.
The epigenomics era largely began more recently, about 2000. [ 2 ] [ 3 ] One major source of epigenetic change is altered methylation of CpG islands at the promoter region of genes (see DNA methylation in cancer ). A number of recently devised methods can assess the DNA methylation status in cancers versus normal tissues. [ 4 ] Some methods assess methylation of CpGs located in different classes of loci, including CpG islands, shores, and shelves as well as promoters, gene bodies, and intergenic regions. [ 5 ] Cancer is also a major focus of epigenetic studies.
Access to whole cancer genome sequencing is important to cancer (or cancer genome) research because:
Access to methylation profiling is important to cancer research because:
The first cancer genome was sequenced in 2008. [ 6 ] This study sequenced a typical acute myeloid leukaemia (AML) genome and its normal counterpart genome obtained from the same patient. The comparison revealed ten mutated genes. Two were already thought to contribute to tumor progression: an internal tandem duplication of the FLT3 receptor tyrosine kinase gene, which activates kinase signaling and is associated with a poor prognosis and a four base insertion in exon 12 of the NPM1 gene (NPMc). These mutations are found in 25–30% of AML tumors and are thought to contribute to disease progression rather than to cause it directly.
The remaining 8 were new mutations and all were single base changes: Four were in families that are strongly associated with cancer pathogenesis ( PTPRT , CDH24, PCLKC and SLC15A1 ). The other four had no previous association with cancer pathogenesis. They did have potential functions in metabolic pathways that suggested mechanisms by which they could act to promote cancer (KNDC1, GPR124 , EB12, GRINC1B)
These genes are involved in pathways known to contribute to cancer pathogenesis, but before this study most would not have been candidates for targeted gene therapy. This analysis validated the approach of whole cancer genome sequencing in identifying somatic mutations and the importance of parallel sequencing of normal and tumor cell genomes. [ 9 ]
In 2011, the genome of an exceptional bladder cancer patient whose tumor had been eliminated by the drug everolimus was sequenced, revealing mutations in two genes, TSC1 and NF2 . The mutations disregulated mTOR , the protein inhibited by everolimus, allowing it to reproduce without limit. As a result, in 2015, the Exceptional Responders Initiative was created at the National Cancer Institute. The initiative allows such exceptional patients (who have responded positively for at least six months to a cancer drug that usually fails) to have their genomes sequenced to identify the relevant mutations. Once identified, other patients could be screened for those mutations and then be given the drug. In 2016 To that end, a nationwide cancer drug trial began in 2015, involving up to twenty-four hundred centers. Patients with appropriate mutations are matched with one of more than forty drugs. [ 10 ]
In 2014 the Center for Molecular Oncology rolled out the MSK-IMPACT test, a screening tool that looks for mutations in 341 cancer-associated genes. By 2015 more than five thousand patients had been screened. Patients with appropriate mutations are eligible to enroll in clinical trials that provide targeted therapy. [ 10 ]
Genomics technologies include:
Bioinformatics technologies allow the statistical analysis of genomic data. The functional characteristics of oncogenes has yet to be established. Potential functions include their transformational capabilities relating to tumour formation and specific roles at each stage of cancer development.
After the detection of somatic cancer mutations across a cohort of cancer samples, bioinformatic computational analyses can be carried out to identify likely functional and likely driver mutations. There are three main approaches routinely used for this identification: mapping mutations, assessing the effect of mutation of the function of a protein or a regulatory element and finding signs of positive selection across a cohort of tumors. The approaches are not necessarily sequential however, there are important relationships of precedence between elements from the different approaches. Different tools are used at each step. [ 22 ]
Operomics aims to integrate genomics, transcriptomics and proteomics to understand the molecular mechanisms that underlie the cancer development. [ 23 ]
Comparative oncogenomics uses cross-species comparisons to identify oncogenes. This research involves studying cancer genomes, transcriptomes and proteomes in model organisms such as mice, identifying potential oncogenes and referring back to human cancer samples to see whether homologues of these oncogenes are important in causing human cancers. [ 24 ] Genetic alterations in mouse models are similar to those found in human cancers. These models are generated by methods including retroviral insertion mutagenesis or graft transplantation of cancerous cells.
Mutations provide the raw material for natural selection in evolution and can be caused by errors of DNA replication, the action of exogenous mutagens or endogenous DNA damage. The machinery of replication and genome maintenance can be damaged by mutations, or altered by physiological conditions and differential levels of expression in cancer (see references in [ 25 ] ).
As pointed out by Gao et al., [ 26 ] the stability and integrity of the human genome are maintained by the DNA-damage response (DDR) system. Un-repaired DNA damage is a major cause of mutations that drive carcinogenesis. [ 27 ] [ 28 ] If DNA repair is deficient, DNA damage tends to accumulate. Such excess DNA damage can increase mutational errors during DNA replication due to error-prone translesion synthesis . Excess DNA damage can also increase epigenetic alterations due to errors during DNA repair. [ 29 ] [ 30 ] Such mutations and epigenetic alterations can give rise to cancer . DDR genes are often repressed in human cancer by epigenetic mechanisms. Such repression may involve DNA methylation of promoter regions or repression of DDR genes by a microRNA. Epigenetic repression of DDR genes occurs more frequently than gene mutation in many types of cancer (see Cancer epigenetics ). Thus, epigenetic repression often plays a more important role than mutation in reducing expression of DDR genes. This reduced expression of DDR genes is likely an important driver of carcinogenesis.
Nucleotide sequence context influences mutation probability [ 31 ] [ 32 ] [ 33 ] and analysis of mutational (mutable) DNA motifs can be essential for understanding the mechanisms of mutagenesis in cancer. Such motifs represent the fingerprints of interactions between DNA and mutagens, between DNA and repair/replication/modification enzymes. Examples of motifs are the AID motif WRCY/RGYW (W = A or T, R = purine and Y = pyrimidine) with C to T/G/A mutations, [ 33 ] and error-prone DNA pol η attributed AID-related mutations (A to G/C/G) in WA/TW motifs. [ 34 ]
Another (agnostic) way to analyze the observed mutational spectra and DNA sequence context of mutations in tumors involves pooling all mutations of different types and contexts from cancer samples into a discrete distribution. If multiple cancer samples are available, their context-dependent mutations can be represented in the form of a nonnegative matrix. This matrix can be further decomposed into components (mutational signatures) which ideally should describe individual mutagenic factors. [ 35 ] Several computational methods have been proposed for solving this decomposition problem. The first implementation of Non-negative Matrix Factorization (NMF) method is available in Sanger Institute Mutational Signature Framework in the form of a MATLAB package. [ 36 ] On the other hand, if mutations from a single tumor sample are only available, the DeconstructSigs R package [ 37 ] and MutaGene server [ 38 ] may provide the identification of contributions of different mutational signatures for a single tumor sample. In addition, MutaGene server provides mutagen or cancer-specific mutational background models and signatures that can be applied to calculate expected DNA and protein site mutability to decouple relative contributions of mutagenesis and selection in carcinogenesis.
Synthetic lethality arises when a combination of deficiencies in the expression of two or more genes leads to cell death, whereas a deficiency in only one of these genes does not. The deficiencies can arise through mutations, epigenetic alterations or inhibitors of one of the genes.
The therapeutic potential of synthetic lethality as an efficacious anti-cancer strategy is continually improving. Recently, the applicability of synthetic lethality to targeted cancer therapy has heightened due to the recent work of scientists including Ronald A. DePinho and colleagues, in what is termed 'collateral lethality'. Muller et al. found that passenger genes, with chromosomal proximity to tumor suppressor genes, are collaterally deleted in some cancers. [ 39 ] Thus, the identification of collaterally deleted redundant genes carrying out an essential cellular function may be the untapped reservoir for then pursuing a synthetic lethality approach. Collateral lethality therefore holds great potential in identification of novel and selective therapeutic targets in oncology. [ 40 ] In 2012, Muller et al. identified that homozygous deletion of redundant-essential glycolytic ENO1 gene in human glioblastoma (GBM) is the consequence of proximity to 1p36 tumor suppressor locus deletions and may hold potential for a synthetic lethality approach to GBM inhibition. [ 39 ] ENO1 is one of three homologous genes ( ENO2 , ENO3 ) that encodes the mammalian alpha-enolase enzyme. [ 41 ] ENO2, which encodes enolase 2 , is mostly expressed in neural tissues, leading to the postulation that in ENO1 -deleted GBM, ENO2 may be the ideal target as the redundant homologue of ENO1. [ 42 ] Muller found that both genetic and pharmacological ENO2 inhibition in GBM cells with homozygous ENO1 deletion elicits a synthetic lethality outcome by selective killing of GBM cells. [ 39 ] In 2016, Muller and colleagues discovered antibiotic SF2312 as a highly potent nanomolar-range enolase inhibitor which preferentially inhibits glioma cell proliferation and glycolytic flux in ENO1-deleted cells. [ 43 ] SF2312 was shown to be more efficacious than pan-enolase inhibitor PhAH and have more specificity for ENO2 inhibition over ENO1. [ 43 ] Subsequent work by the same team showed that the same approach could be applied to pancreatic cancer , whereby homozygously deleted SMAD4 results in the collateral deletion of mitochondrial malic enzyme 2 ( ME2 ), an oxidative decarboxylase essential for redox homeostasis. [ 44 ] Dey et al. show that ME2 genomic deletion in pancreatic ductal adenocarcinoma cells results in high endogenous reactive oxygen species, consistent with KRAS-driven pancreatic cancer , and essentially primes ME2-null cells for synthetic lethality by depletion of redundant NAD(P)+-dependent isoform ME3. The effects of ME3 depletion were found to be mediated by inhibition of de novo nucleotide synthesis resulting from AMPK activation and mitochondrial ROS-mediated apoptosis. [ 45 ] [ 44 ] Meanwhile, Oike et al. demonstrated the generalizability of the concept by targeting redundant essential-genes in process other than metabolism, namely the SMARCA4 and SMARCA2 subunits in the chromatin-remodeling SWI/SNF complex. [ 46 ]
Some oncogenes are essential for survival of all cells (not only cancer cells). Thus, drugs that knock out these oncogenes (and thereby kill cancer cells) may also damage normal cells, inducing significant illness. However, other genes may be essential to cancer cells but not to healthy cells.
Treatments based on the principle of synthetic lethality have prolonged the survival of cancer patients, and show promise for future advances in reversal of carcinogenesis. A major type of synthetic lethality operates on the DNA repair defect that often initiates a cancer, and is still present in the tumor cells. Some examples are given here.
BRCA1 or BRCA2 expression is deficient in a majority of high-grade breast and ovarian cancers, usually due to epigenetic methylation of its promoter or epigenetic repression by an over-expressed microRNA (see articles BRCA1 and BRCA2 ). BRCA1 and BRCA2 are important components of the major pathway for homologous recombinational repair of double-strand breaks. If one or the other is deficient, it increases the risk of cancer, especially breast or ovarian cancer. A back-up DNA repair pathway, for some of the damages usually repaired by BRCA1 and BRCA2, depends on PARP1 . Thus, many ovarian cancers respond to an FDA-approved treatment with a PARP inhibitor, causing synthetic lethality to cancer cells deficient in BRCA1 or BRCA2. This treatment is also being evaluated for breast cancer and numerous other cancers in Phase III clinical trials in 2016. [ 47 ]
There are two pathways for homologous recombinational repair of double-strand breaks. The major pathway depends on BRCA1, PALB2 and BRCA2 while an alternative pathway depends on RAD52. [ 48 ] Pre-clinical studies, involving epigenetically reduced or mutated BRCA-deficient cells (in culture or injected into mice), show that inhibition of RAD52 is synthetically lethal with BRCA-deficiency. [ 49 ]
Mutations in genes employed in DNA mismatch repair (MMR) cause a high mutation rate. [ 50 ] In tumors, such frequent subsequent mutations often generate "non-self" immunogenic antigens. A human Phase II clinical trial, with 41 patients, evaluated one synthetic lethal approach for tumors with or without MMR defects. [ 51 ] The product of gene PD-1 ordinarily represses cytotoxic immune responses. Inhibition of this gene allows a greater immune response. When cancer patients with a defect in MMR in their tumors were exposed to an inhibitor of PD-1, 67–78% of patients experienced immune-related progression-free survival. In contrast, for patients without defective MMR, addition of PD-1 inhibitor generated only 11% of patients with immune-related progression-free survival. Thus inhibition of PD-1 is primarily synthetically lethal with MMR defects.
ARID1A , a chromatin modifier, is required for non-homologous end joining , a major pathway that repairs double-strand breaks in DNA, [ 52 ] and also has transcription regulatory roles. [ 53 ] ARID1A mutations are one of the 12 most common carcinogenic mutations. [ 54 ] Mutation or epigenetically decreased expression [ 55 ] of ARID1A has been found in 17 types of cancer. [ 56 ] Pre-clinical studies in cells and in mice show that synthetic lethality for ARID1A deficiency occurs by either inhibition of the methyltransferase activity of EZH2, [ 57 ] [ 58 ] or with addition of the kinase inhibitor dasatinib. [ 59 ]
Another approach is to individually knock out each gene in a genome and observe the effect on normal and cancerous cells. [ 60 ] [ 61 ] If the knockout of an otherwise nonessential gene has little or no effect on healthy cells, but is lethal to cancerous cells containing a mutated oncogene, then the system-wide suppression of the suppressed gene can destroy cancerous cells while leaving healthy ones relatively undamaged. The technique was used to identify PARP-1 inhibitors to treat BRCA1/BRCA2-associated cancers. [ 62 ] [ 63 ] In this case, the combined presence of PARP-1 inhibition and of the cancer-associated mutations in BRCA genes is lethal only to the cancerous cells.
The Cancer Genome Project is an initiative to map out all somatic mutations in cancer. The project systematically sequences the exons and flanking splice junctions of the genomes of primary tumors and cancerous cell lines. COSMIC software displays the data generated from these experiments. As of February 2008, the CGP had identified 4,746 genes and 2,985 mutations in 1,848 tumours.
The Cancer Genome Anatomy Project includes information of research on cancer genomes, transcriptomes and proteomes.
Progenetix is an oncogenomic reference database, presenting cytogenetic and molecular-cytogenetic tumor data.
Oncomine has compiled data from cancer transcriptome profiles.
The integrative oncogenomics database IntOGen and the Gitools datasets integrate multidimensional human oncogenomic data classified by tumor type. The first version of IntOGen focused on the role of deregulated gene expression and CNV in cancer. [ 64 ] A later version emphasized mutational cancer driver genes across 28 tumor types,. [ 65 ] [ 66 ] All releases of IntOGen data are made available at the IntOGen database.
The International Cancer Genome Consortium is the biggest project to collect human cancer genome data. The data is accessible through the ICGC website. The BioExpress® Oncology Suite contains gene expression data from primary, metastatic and benign tumor samples and normal samples, including matched adjacent controls. The suite includes hematological malignancy samples for many well-known cancers.
Specific databases for model animals include the Retrovirus Tagged Cancer Gene Database (RTCGD) that compiled research on retroviral and transposon insertional mutagenesis in mouse tumors.
Mutational analysis of entire gene families revealed that genes of the same family have similar functions, as predicted by similar coding sequences and protein domains . Two such classes are the kinase family, involved in adding phosphate groups to proteins and the phosphatase family, involved with removing phosphate groups from proteins. [ 67 ] These families were first examined because of their apparent role in transducing cellular signals of cell growth or death. In particular, more than 50% of colorectal cancers carry a mutation in a kinase or phosphatase gene. Phosphatidylinositold 3-kinases ( PIK3CA ) gene encodes for lipid kinases that commonly contain mutations in colorectal, breast, gastric, lung and various other cancers. [ 68 ] [ 69 ] Drug therapies can inhibit PIK3CA. Another example is the BRAF gene, one of the first to be implicated in melanomas. [ 70 ] BRAF encodes a serine / threonine kinase that is involved in the RAS-RAF- MAPK growth signaling pathway. Mutations in BRAF cause constitutive phosphorylation and activity in 59% of melanomas. Before BRAF, the genetic mechanism of melanoma development was unknown and therefore prognosis for patients was poor. [ 71 ]
Mitochondrial DNA (mtDNA) mutations are linked the formation of tumors. Four types of mtDNA mutations have been identified: [ 72 ]
Point mutations have been observed in the coding and non-coding region of the mtDNA contained in cancer cells. In individuals with bladder, head/neck and lung cancers, the point mutations within the coding region show signs of resembling each other. This suggests that when a healthy cell transforms into a tumor cell (a neoplastic transformation) the mitochondria seem to become homogenous. Abundant point mutations located within the non-coding region, D-loop , of the cancerous mitochondria suggest that mutations within this region might be an important characteristic in some cancers. [ 72 ]
This type of mutation is sporadically detected due to its small size ( < 1 kb). The appearance of certain specific mtDNA mutations (264-bp deletion and 66-bp deletion in the complex 1 subunit gene ND1) in multiple types of cancer provide some evidence that small mtDNA deletions might appear at the beginning of tumorigenesis . It also suggests that the amount of mitochondria containing these deletions increases as the tumor progresses. An exception is a relatively large deletion that appears in many cancers (known as the "common deletion"), but more mtDNA large scale deletions have been found in normal cells compared to tumor cells. This may be due to a seemingly adaptive process of tumor cells to eliminate any mitochondria that contain these large scale deletions (the "common deletion" is > 4 kb). [ 72 ]
Two small mtDNA insertions of ~260 and ~520 bp can be present in breast cancer, gastric cancer, hepatocellular carcinoma (HCC) and colon cancer and in normal cells. No correlation between these insertions and cancer are established. [ 73 ]
The characterization of mtDNA via real-time polymerase chain reaction assays shows the presence of quantitative alteration of mtDNA copy number in many cancers. Increase in copy number is expected to occur because of oxidative stress. On the other hand, decrease is thought to be caused by somatic point mutations in the replication origin site of the H-strand and/or the D310 homopolymeric c-stretch in the D-loop region, mutations in the p53 (tumor suppressor gene) mediated pathway and/or inefficient enzyme activity due to POLG mutations. Any increase/decrease in copy number then remains constant within tumor cells. The fact that the amount of mtDNA is constant in tumor cells suggests that the amount of mtDNA is controlled by a much more complicated system in tumor cells, rather than simply altered as a consequence of abnormal cell proliferation. The role of mtDNA content in human cancers apparently varies for particular tumor types or sites. [ 72 ]
57.7% (500/867) contained somatic point putations and of the 1172 mutations surveyed 37.8% (443/1127) were located in the D-loop control region, 13.1% (154/1172) were located in the tRNA or rRNA genes and 49.1% (575/1127) were found in the mRNA genes needed for producing complexes required for mitochondrial respiration.
Some anticancer drugs target mtDNA and have shown positive results in killing tumor cells. Research has used mitochondrial mutations as biomarkers for cancer cell therapy. It is easier to target mutation within mitochondrial DNA versus nuclear DNA because the mitochondrial genome is much smaller and easier to screen for specific mutations. MtDNA content alterations found in blood samples might be able to serve as a screening marker for predicting future cancer susceptibility as well as tracking malignant tumor progression. Along with these potential helpful characteristics of mtDNA, it is not under the control of the cell cycle and is important for maintaining ATP generation and mitochondrial homeostasis. These characteristics make targeting mtDNA a practical therapeutic strategy. [ 72 ]
Several biomarkers can be useful in cancer staging, prognosis and treatment. They can range from single-nucleotide polymorphisms (SNPs), chromosomal aberrations , changes in DNA copy number, microsatellite instability, promoter region methylation , or even high or low protein levels. [ 90 ] Between 2013 and 2019 only 6.8% of people with cancer in 2 US states underwent genetic testing, suggesting broad under-utilization of information that could improve treatment decisions and patient outcomes. [ 91 ] | https://en.wikipedia.org/wiki/Oncogenomics |
Adenovirus varieties have been explored extensively as a viral vector for gene therapy and also as an oncolytic virus . [ 1 ]
Of the many different viruses being explored for oncolytic potential, an adenovirus was the first to be approved by a regulatory agency, the genetically modified H101 strain. It gained regulatory approval in 2005 from China's State Food and Drug Administration (SFDA) for the treatment of head and neck cancer. [ 2 ] [ 3 ]
Adenoviruses have so far been through three generations of development. [ 4 ] Some of the strategies for modification of adenoviruses are described below.
For adenovirus replication to occur, the host cell must be induced into S phase by viral proteins interfering with cell cycle proteins. The adenoviral E1A gene is responsible for inactivation of several proteins, including retinoblastoma , allowing entry into S-phase. The adenovirus E1B55kDa gene cooperates with another adenoviral product, E4ORF6, to inactivate p53 , thus preventing apoptosis . It was initially proposed that an adenovirus mutant lacking the E1B55kDa gene, dl1520 (ONYX-015), could replicate selectively in p53 deficient cells. [ citation needed ]
A conditionally replicative adenovirus (CRAd) with a 24 base pair deletion in the retinoblastoma -binding domain of the E1A protein ( Ad5- Δ24E3 ), is unable to silence retinoblastoma, and therefore unable to induce S-phase in host cells. [ 5 ] This restricts Ad5-Δ24E3 to replication only in proliferating cells, such as tumour cells. [ citation needed ]
The most commonly used group of adenoviruses is serotype 5 (Ad5), whose binding to host cells is initiated by interactions between the cellular coxsackie virus and adenovirus receptor (CAR), and the knob domain of the adenovirus coat protein trimer . CAR is necessary for adenovirus infection. [ 6 ] Although expressed widely in epithelial cells , CAR expression in tumours is extremely variable, leading to resistance to Ad5 infection. [ 6 ] Retargeting of Ad5 from CAR, to another receptor that is ubiquitously expressed on cancer cells, may overcome this resistance. [ 6 ]
Arming with Transgenes
To enhance the efficacy, therapeutic transgenes are integrated into oncolytic adenovirus [ 16 ]
Immunostimulatory genes Like interferon α (IFNα), [ 17 ] tumor necrosis factor alpha (TNFα), [ 18 ] and interleukin 12 (IL-12) [ 19 ] have been integrated into oncolytic adenovirus to enhance immune response inside the tumor microenvironment. When these molecules selectively expressed in tumor cells, oncolytic adenoviruses promote immune responses against tumor and minimize systemic side effects [ 20 ]
Oncolytic adenoviruses have been genetically modified with transgene encoding for granulocyte-macrophage colony-stimulating factor (GM-CSF) to enhance tumor antigens presentation by antigen-presenting cells (APCs). This approach aims to improve recognition of tumor by T-cell and subsequent immune responses, [ 21 ] [ 22 ]
Oncolytic adenoviruses have been genetically engineered to express checkpoint inhibitors (CTLA-4, anti-PD-L1 antibodies) to release brake of T-cell activity, [ 23 ] [ 24 ] and to express costimulatory molecules (CD40L, 4-1BBL) to augment T-cell activation and proliferation, [ 25 ] [ 26 ]
H101 and the very similar Onyx-015 have been engineered to remove a viral defense mechanism that interacts with a normal human gene p53 , which is very frequently dysregulated in cancer cells. [ 3 ] Despite the promises of early in vivo lab work, these viruses do not specifically infect cancer cells, but they still kill cancer cells preferentially. [ 3 ] While overall survival rates are not known, short-term response rates are approximately doubled for H101 plus chemotherapy when compared to chemotherapy alone. [ 3 ] It appears to work best when injected directly into a tumour, and when any resulting fever is not suppressed. [ 3 ] Systemic therapy (such as through infusion through an intravenous line) is desirable for treating metastatic disease. [ 27 ] It is now marketed under the brand name Oncorine . [ 28 ]
dl1520 is an experimental oncolytic virus created by genetically engineering a human adenovirus. [ 29 ] Onyx Pharmaceuticals used dl1520 under the brand name ONYX-015 in clinical trials as a possible treatment for cancer. [ 30 ] This virus, an Ad2/Ad5 recombinant, contains two E1B-55kDa gene mutations allowing the virus to selectively replicate in and lyse p53-deficient cancer cells. [ 31 ]
Traditional research has focussed on species C Adenovirus serotype 5 (Ad5) for creating oncolytic vaccines for the potential use as cancer treatment. However, recent data suggests that it may not be the best virus serotype for deriving all oncolytic agents for treating human malignancies. [ 32 ] For example, oncolytic vaccines based on the Ad5 serotype have relatively poor clinical efficacy as monotherapies. [ 33 ] [ 34 ] [ 35 ] [ 36 ] The need for increased potency (infectivity and lytic activity) has led to an expanded search involving a larger number of less well studied adenovirus serotypes. [ citation needed ]
One non-species C oncolytic adenovirus currently in development is ColoAd1 . It was created using a process of “directed evolution”. This involves the creation of new viral variants or serotypes specifically directed against tumour cells via rounds of directed selection using large populations of randomly generated recombinant precursor viruses. The increased biodiversity produced by the initial homologous recombination step provides a large random pool of viral candidates which can then be passed through a series of selection steps designed to lead towards a pre-specified outcome (e.g. higher tumor specific activity) without requiring any previous knowledge of the resultant viral mechanisms that are responsible for that outcome. [ 37 ] One particular application of this approach produced ColoAd1, which is a novel Ad11p/Ad3 chimeric Group B oncolytic virus with specificity for human colon cancer and a broad spectrum of anti-cancer activity in common solid tumours. [ 37 ] The therapeutic efficacy of ColoAd1 is currently being evaluated in three ongoing clinical trials (see the EU Clinical Trials Register for further details).
ColoAd1 potency can be further enhanced via the use of therapeutic transgenes, which can be introduced into the ColoAd1 genome without compromising the selectivity or activity of the virus. Recent studies with ColoAd1 have shown a unique mechanism of cell death similar to Oncosis with expression of inflammatory cell death markers and cell membrane blistering and have highlighted mechanisms by which ColoAd1 alters host cell metabolism to facilitate replication. [ 38 ] [ 39 ]
Tumours form in cells when mutations in genes involved in cell cycle control and apoptosis accumulate over time. [ 40 ] Most tumours studied, have defects in the p53 tumor suppressor pathway. [ 41 ] p53 is a transcription factor that plays a role in apoptosis , cell cycle and DNA repair . It blocks cell progression in response to cellular stress or DNA damage. Many viruses replicate by altering the cell cycle and exploiting the same pathways that are altered in cancer cells. [ 42 ] E1B proteins produced by adenoviruses protect the infected cell by binding to and degrading the p53 transcription factors, [ 43 ] preventing it from targeting the cell for apoptosis. This allows the virus to replicate, package its genome, lyse the cell and spread to new cells. [ citation needed ]
This gave rise to the idea that an altered adenovirus could be used to target and eliminate cancer cells. Onyx-015 is an adenovirus that was developed in 1987 with the function of the E1B gene knocked out , [ 44 ] meaning cells infected with Onyx-015 are incapable of blocking p53's function. If Onyx-015 infects a normal cell, with a functioning p53 gene, it will be prevented from multiplying by the action of the p53 transcription factor. However, if Onyx-015 infects a p53 deficient cell it should be able to survive and replicate, resulting in selective destruction of cancer cells.
There are as of 2023 several ongoing and finished clinical trial testing oncolytic adenoviruses. [ 45 ] [ 46 ] [ 47 ]
ColoAd1 from PsiOxus Therapeutics has entered Phase I/II clinical study with its oncolytic vaccine. Phase I of the trial recruited patients with metastatic solid tumors and showed evidence for virus replication within tumour sites after intravenous delivery. The second phase of the ColoAd1 study will involve the comparison of intra-tumoural versus intravenous injection to examine viral replication, viral spread, tumour necrosis and anti-tumoural immune responses (see the EU Clinical Trials Register for further details).
Patents for the therapeutic use of ONYX-015 are held by ONYX Pharmaceuticals [ 48 ] [ 49 ] and it was used in combination with the standard chemotherapeutic agents cisplatin and 5-fluorouracil to combat head and neck tumours. [ 50 ] Onyx-015 has been extensively tested in clinical trials, with the data indicating that it is safe and selective for cancer. [ 51 ] However, limited therapeutic effect has been demonstrated following injection and systemic spread of the virus was not detected. [ 52 ] ONYX-015 when combined with chemotherapy , however, proved reasonably effective in a proportion of cases. During these trials a plethora of reports emerged challenging the underlying p53-selectivity, with some reports showing that in some cancers with a wild-type p53 ONYX-015 actually did better than in their mutant p53 counterparts. These reports slowed the advancement through Phase III trials in the US, however recently China licensed ONYX-015 for therapeutic use as H101 . [ 53 ] Further development of Onyx-015 was abandoned in the early 2000s, the exclusive rights being licensed to the Chinese company, Shanghai Sunway Biotech. On November 17, 2005, the Chinese State Food and Drug Administration approved H101, an oncolytic adenovirus similar to Onyx-015 (E1B-55K/E3B-deleted), for use in combination with chemotherapy for the treatment of late-stage refractory nasopharyngeal cancer . [ 54 ] [ 55 ] Outside of China, the push to the clinic for ONYX-015 has been largely been discontinued for financial reasons and until a real mechanism can be found. [ 56 ] | https://en.wikipedia.org/wiki/Oncolytic_adenovirus |
Many variants of herpes simplex virus have been considered for viral therapy of cancer; the early development of these was thoroughly reviewed in the journal Cancer Gene Therapy in 2002. [ 1 ] This page describes (in the order of development) the most notable variants—those tested in clinical trials: G207, HSV1716, NV1020 and Talimogene laherparepvec (previously Oncovex-GMCSF). These attenuated versions are constructed by deleting viral genes required for infecting or replicating inside normal cells but not cancer cells, such as ICP34.5 , ICP6/UL39, and ICP47 .
HSV1716 is a first generation oncolytic virus developed by the Glasgow Institute of Virology , and subsequently by Virttu Biologics (formerly Crusade Laboratories, a spin-out from The Institute of Virology), to selectively destroy cancer cells. The virus has the trade name SEPREHVIR . It is based on the herpes simplex virus (HSV-1). The HSV1716 strain has a deletion of the gene ICP34.5 . ICP34.5 is a neurovirulence gene (enabling the virus to replicate in neurons of the brain and spinal cord). Deletion of this gene provides the property of tumor-selective replication to the virus (i.e. largely prevents replication in normal cells, while still allowing replication in tumor cells), although it also reduces replication in tumor cells as compared to wild type HSV. [ 2 ] [ 3 ]
A vital part of the normal mechanism of HSV-1, the ICP34.5 protein has been proposed to condition post-mitotic cells for viral replication . With no ICP34.5 gene, the HSV-1716 variant is unable to overcome normal defences of healthy differentiated cells (mediated by PKR ) to replicate efficiently. However, tumour cells have much weaker PKR-linked defences, which may be the reason why HSV1716 effectively kills a wide range of tumour cell lines in tissue culture .
An HSV1716 variant, HSV1716NTR is an oncolytic virus generated by inserting the enzyme NTR into the virus HSV1716 as a GDEPT strategy. [ 4 ] In-vivo, administration of the prodrug CB1954 to athymic mice bearing either A431 or A2780 tumour xenografts, 48 hours after intra-tumoral injection of HSV1790, resulted in a marked reduction in tumour volumes and significantly improved survival compared to administration of virus alone. A similar approach has been taken with a variant of HSV1716 that expresses the noradrenaline transporter to deliver radioactive iodine into individual infected cancer cells, by tagging a protein that cancer cells transport. The nor-adrenaline transporter specifically transports a compound containing radioactive iodine across the cell membrane, using genes from the virus. The only cells in the body that receive a significant radiation dose are those infected and their immediate neighbours. [ 5 ]
G207 was constructed as a second-generation vector from HSV-1 laboratory strain F, with ICP34.5 deleted and the ICP6 gene inactivated by insertion of the E. coli LacZ gene. [ 12 ]
Two phase I clinical trials in glioma were completed. [ 13 ] [ 14 ] [ 15 ] The results of the first trial were published simultaneously with the first trial of HSV1716 in 2000, with commentators praising the demonstration of safety of these viruses when injected into brain tumours but also expressing disappointment that viral replication could not be demonstrated due to the difficulty of taking biopsies from brain tumours. [ 16 ]
NV1020 is an oncolytic herpes virus initially developed by Medigene Inc. and licensed for development by Catherex Inc. in 2010. [ 17 ] NV1020 has a deletion of just one copy of the ICP34.5 gene and ICP6 is intact. [ 1 ] A direct comparison of NV1020 and G207 in a mouse model of peritoneal cancer showed that NV1020 is more effective at lower doses. [ 18 ]
A Phase I/II study completed in 2008 evaluating NV1020 for treatment of metastatic colorectal cancer in the liver. [ 19 ] The study assessed tumour response by CT scan and FDG-PET scans, showing 67% of patients had an initial increase in tumour size then followed by a decrease in 64% of patients. [ 20 ] [ 18 ]
Talimogene laherparepvec is the USAN name for the oncolytic virus also known as 'OncoVEX GM-CSF'. It was developed by BioVex Inc. (Woburn, MA, USA & Oxford, UK) until BioVex was purchased by Amgen in January 2011. [ 21 ]
It is a second-generation herpes simplex virus based on the JS1 strain and expressing the immune stimulatory factor GM-CSF . [ 22 ] [ 23 ] Like other oncolytic versions of HSV it has a deletion of the gene encoding ICP34.5, which provides tumor selectivity. [ 24 ] It also has a deletion of the gene encoding ICP47, a protein that inhibits antigen presentation, [ 25 ] and an insertion of a gene encoding GM-CSF , an immune stimulatory cytokine. [ 2 ] [ 3 ] Deletion of the gene encoding ICP47 also puts the US11 gene (a late gene) under control of the immediate early ICP47 promoter. The earlier and greater expression of US11 (also involved in overcoming PKR-mediated responses) largely overcomes the reduction in replication in tumor cells of ICP34.5-deleted HSV as compared to wild type virus, but without reducing tumor selectivity.
Including phase III : See Talimogene laherparepvec | https://en.wikipedia.org/wiki/Oncolytic_herpes_virus |
Oncomatryx Biopharma S. L. is a pharmaceutical biotechnology company that develops personalized treatments against invasive cancer as well as tests for its early detection. Established by Laureano Simón, PhD, Oncomatryx thus engages twofold in the fight against invasive kinds of cancer, such as pancreatic cancer or invasive breast cancer , all of which have high mortality rates.
Oncomatryx's research focuses on peritumoral stroma , which has been found to take part in promoting cancer invasiveness and curtailing treatment efficacy. [ 1 ]
Laureano Simón began his business career in 2000 with the creation of Progenika Biopharma S.A., a personalized medicine company which was acquired by Grifols in February 2013. [ 2 ]
Dr. Simón holds a Ph.D. in Chemical Sciences (Molecular Biology) by the Universidad Autónoma de Madrid , a master's degree in Biotechnology by the University of Navarra , an MSc by the “ University of Wisconsin-Madison ” and a bachelor's degree in Pharmacy by the University of Santiago de Compostela . He has patented, among others, clinical products such as BLOODchip and LIPOchip.
The company bases its R&D on the recent discovery that tumor cells generate changes in the cells that surround them as well as in the extracellular matrix, facilitating invasion metastases. [ 3 ] [ 4 ] Oncomatryx and its collaborators and advisors have proved that peritumoral stroma, which is constituted by mesenchymal cells and extracellular matrix, plays a key role in tumor invasiveness and metastasis, at the same time being a physical barrier that prevents anti-cancer agents from reaching tumor cells. [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ] [ 11 ] [ 12 ] [ 13 ] [ 14 ] [ 15 ] [ 16 ] [ 17 ] [ 18 ]
Oncomatryx is developing a new generation of biological anti-tumor drugs, combining cytotoxic molecules and monoclonal antibodies specifically directed towards tumor associated stroma.
Oncomatryx collaborates with the Institut für Zell Biologie und Immunologie of the University of Stuttgart , [ 19 ] [ 20 ] the University of Valladolid, Hospital Universitario Marqués de Valdecilla, Hospital Universitario Central de Asturias, the Centro Nacional de Investigaciones Oncológicas, National Jewish Health and Breast Cancer Research among others.
Currently, invasive cancer is associated with a very short life expectancy . In the case of pancreatic cancer, which unfortunately is almost always already in invasive stages at the time of diagnosis, only between 1% and 4% of patients survive for five years after diagnosis. [ 21 ]
Oncomatryx has developed molecular diagnostic tests to predict the invasiveness of breast tumors (DMTXbreastScan) and pancreas, colon, lung, and head and neck tumors (DMTXinvaScan). These tests have already been used successfully in hospitals in Andalucia, Asturias, Cantabria, Catalonia, Galicia, Madrid, Navarre, the Basque Country and Valencia in Spain. In addition, the universities of Columbia (USA), Munich (Germany) and Copenhagen (Denmark) have also proven their high sensitivity and specificity. DMTXinvaScan and DMTXbreastScan were presented to the international medical community at the Annual Conference of the United States and Canadian Academy of Pathology, held in Baltimore, USA, in March 2013. Specifically, DMTXbreastScan helps to determine, at the moment of first diagnosis, if a breast tumor has the capacity to develop metastases. This test, which is already being used in USA hospitals such as Johns Hopkins Hospital in Baltimore and Cedars Sinai Hospital in Los Angeles, has 93.5% sensitivity and 94.2% specificity in detecting invasive breast tumors in biopsies. In addition, it helps to predict if a benign lesion of the breast, such as a papilloma, will turn into a malignant tumor, so the treatment can be adapted more effectively for each patient. [ 22 ] [ 23 ]
Antitumor drugs developed by Oncomatryx, which specifically target the peritumoral stroma, are currently in pre-clinical development phase and will enter clinical trials in 2015.
For this purpose, the company has reached an agreement with the U.S. National Jewish Health hospital and Case Western Reserve University [ 24 ] [ 25 ] [ 26 ] whereby Oncomatyx will use a human protein, Cystatin-C, as a principle asset for the development of drugs against invasive breast cancer.
Oncomatryx has also signed collaboration agreements with the Universität Stuttgart (Germany), the Universidad de Valladolid (Spain), and other biotech companies for the development of immunotoxins and ADCs targeted specifically towards the stromal component of tumors. This strategy allows for attacking directly the cells responsible for invasion and metastasis in cancer. These immunotoxins and ADCs are specifically directed against two proteins, known as MTX1 and MTX2, which are expressed only in the peritumoral stroma that surround the tumor and facilitates its progression and metastasis. [ 27 ] | https://en.wikipedia.org/wiki/Oncomatryx |
Oncometabolism is the field of study that focuses on the metabolic changes that occur in cells that make up the tumor microenvironment (TME) and accompany oncogenesis and tumor progression toward a neoplastic state. [ 1 ]
Cells with increased growth and survivability differ from non-tumorigenic cells in terms of metabolism . [ 2 ] The Warburg Effect , which describes how cancer cells change their metabolism to become more oncogenic in order to proliferate and eventually invade other tissues in a process known as metastasis . [ 1 ]
The chemical reactions associated with oncometabolism are triggered by the alteration of oncogenes , which are genes that have the potential to cause cancer . [ 3 ] These genes can be functional and active during physiological conditions, producing normal amounts of metabolites. Their upregulation as a result of DNA damage can result in an overabundance of these metabolites, and lead to tumorigenesis. These metabolites are known as oncometabolites, and can act as biomarkers . [ 4 ]
In the 1920s, Otto Heinrich Warburg discovered an intriguing bioenergetic phenotype shared by most tumor cells: a higher-than-normal reliance on lactic acid fermentation for energy generation. He is known as the "Father of Oncometabolism". [ 1 ] [ 2 ] Although the roots of this research field trace back to the 1920s, it was only recently recognized [ 1 ] Over the last decade, research on cancer progression has focused on the role of shifting metabolic pathways for both the cancer and immune cells, leading to an increase interest in characterizing the metabolic alterations that cells undergo in the TME . [ 5 ]
In the absence of hypoxic conditions (i.e. physiological levels of oxygen), cancer cells preferentially convert glucose to lactate, according to Otto H. Warburg, who believed that aerobic glycolysis was the key metabolic change in cancer cell malignancy. The "Warburg effect" was later coined to describe this metabolic shift. [ 6 ] Warburg thought this change in metabolism was due to mitochondrial "respiration injury", but this interpretation was questioned by other researchers in 1956 showing that intact and functional cytochromes detected in most tumor cells clearly speak against a general mitochondrial dysfunction. [ 7 ] Furthermore, Potter et al. and several other authors provided significant evidence that oxidative phosphorylation and a normal Krebs cycle persist in the vast majority malignant tumors, adding to the growing body of evidence that most cancers exhibit the Warburg effect while maintaining a proper mitochondrial respiration. [ 6 ] [ 8 ] Dang et al. [ 9 ] in 2008 provided evidence that the tumor tissue sections used in Warburg's experiments should have been thinner for the oxygen diffusion constants employed, implying that the tissue slices studied were partially hypoxic and the calculated critical diffusion distance was of 470 micrometers. [ 6 ] As a result, endless debates and discussions about Warburg's discovery took place and have piqued the interest of scientists all over the world, which has helped bring attention to cell metabolism in cancer and immune cells and the use of modern technology to discover what these pathways are and how they are modified as well as potential therapeutic targets.
Carcinogenic cells undergo a metabolic rewiring during oncogenesis, and oncometabolites play an important role. In cancer, there are several reprogrammed metabolic pathways that help cells survive when nutrients are scarce: Aerobic glycolysis , an increase in glycolytic flux, also known as the Warburg effect, allows glycolytic intermediates to supply subsidiary pathways to meet the metabolic demands of proliferating tumorigenic cells. [ 10 ] Another studied reprogrammed pathway is gain of function of the oncogene MYC . This gene encodes a transcription factor that boosts the expression of a number of genes involved in anabolic growth via mitochondrial metabolism. [ 11 ] Oncometabolite production is another example of metabolic deregulation. [ 12 ]
Oncometabolites are metabolites whose abundance increases markedly in cancer cells through loss-of-function or gain-of-function mutations in specific enzymes involved in their production, the accumulation of these endogenous metabolites initiates or sustains tumor growth and metastasis. [ 13 ] Cancer cells rely on aerobic glycolysis, which is reached through defects in enzymes involved in normal cell metabolism, this allows the cancer cells to meet their energy needs and divert acetyl-CoA from the TCA cycle to build essential biomolecules such as amino acids and lipids . [ 14 ] These defects cause an overabundance of endogenous metabolites , which are frequently involved in critical epigenetic changes and signaling pathways that have a direct impact on cancer cell metabolism. [ 15 ]
IDH2
Oncometabolite dysregulation and cancer progression are linked to epigenetic changes in cancer cells. Several mechanisms have been linked to D -2-hydroxyglutarate, succinate, and fumarate with the inhibition of α-KG–dependent dioxygenases, this causes epigenetic changes that affect the expression of genes involved in cell differentiation and the development of malignant characteristics. [ 27 ] The group of Timothy A. Chan [ 28 ] described a mechanism by which abnormal accumulation of the oncometabolite D -2-hydroxyglutarate in brain tumor samples increased DNA methylation, a process that has been shown to play a key role in oncogenesis. [ 29 ] On the other hand, in paraganglioma cells, succinate and fumarate were found to methylate histones, effectively silencing the genes PNMT and KRT19, which are involved in neuroendocrine differentiation and epithelial-mesenchymal transition, respectively. [ 30 ]
The discovery of oncometabolites has ushered in a new era in cancer biology, one that has the potential to improve patient care. The discovery of new therapeutic and reliable markers that exploit vulnerabilities of cancer cells, are being used to targeting either upstream or downstream effectors of these pathways. [ 15 ] Oncometabolites can be used as diagnostic biomarkers and may be able to assist oncologists in making more precise decisions in early stages of tumorigenesis, particularly in predicting more aggressive tumor behavior. [ 4 ]
The detection of D -2-hydroxyglutarate in glioma patients using proton magnetic resonance spectroscopy (MRS) has been shown to be a noninvasive procedure. The presence of IDH1 or IDH2 mutations was linked to the detection of this oncometabolite 100 percent of the time. [ 31 ] [ 27 ] IDH2/R140Q is a specific mutation that has shown promising results after its inhibition by the small molecule AGI-6780. [ 32 ] Therefore, limiting the supply of D -2-hydroxyglutarate by inhibiting the detected mutant IDH enzymes could be a good therapeutical approach to IDH-mutant cancers. [ 33 ]
IHC staining has been shown to be a useful diagnostic tool for prioritizing patients for SDH mutation testing in early stages of cancer. The absence of SDHB in IHC staining would be linked to the presence of SDH oncogene mutations. [ 34 ] The already commercialized drug decitabine ( Dacogen® ) could be an effective therapy to repress the migration capacities of SDHB-mutant cells, [ 30 ]
IHC staining for FH is used to detect lack of this protein in patients with papillary renal cell carcinoma type 2. [ 35 ] The lack of FH in renal carcinoma cells induces pro-survival metabolic adaptations where several cascades are affected. [ 36 ]
Downregulation of glycine-N-methyltransferase has been linked to hepatocellular carcinoma and pancreatic cancer. Serving this as a reliable marker for oncogenesis. [ 22 ] When compared to patients with deletions in GNMT, patients with no deletions early-stage pancreatic cancer had twice the median months overall survival. [ 23 ]
Metabolomics can be applied to oncometabolism, since the changes in cancer's genomic, transcriptomic, and proteomic profiles can result in changes in downstream metabolic pathways. With this information we can elucidate the responsible pathways and oncometabolites for various diseases. Actually, through the use of this technique, the dysregulation of the pyruvate kinase enzyme in glucose metabolism was discovered in cancer cells. Another common used technique is glucose or glutamine labeled with 13C to show that the TCA cycle is used to generate large amounts of fatty acids (phospholipids) and to replenish the TCA cycle intermediates. [ 37 ] But oncometabolomics does not necessarily need to be used on cancer cells, but on cells immediately surrounding them in the TME . [ 38 ]
Metabolomics applied to cancer has the potential to significantly improve current oncological treatments and has a great diagnostic value, since metabolic changes are the prequel of phenotypic changes in cells (thus tissues and organs) making it suitable for early detection of difficult-to-detect cancers. [ 14 ] This also leads to a more personalized medicine and customize an individual's cancer treatment according to their specific oncometabolite profiles, which would allow for better cancer therapy customization or informed adjustments. [ 13 ] [ 39 ]
Ingenuity Pathway Analysis (IPA) is a metabolic pathway analysis software package that helps researchers model, analyze, and comprehend complex biological systems by associating specific metabolites with potential metabolic pathways for data analysis. [ 40 ] This software has been used by researchers to elucidate regulatory networks on oncometabolites like hydroxyglutarate. [ 41 ]
Metabolights is an open-access database for metabolomics research that collects all experimental data from leading journals' metabolic experiments. [ 42 ] Since its initial release in 2012, the MetaboLights repository has seen consistent year-on-year growth. It is a resource that surged in response to the needs of the scientific community to easy access to metabolite data. [ 43 ] [ 44 ]
Cancer research has been ongoing for centuries, trying to elucidate the origin of its cause. As cancer research evolves with time, the scientific community tends to pay more attention to cell metabolism and how to target these metabolic needs and changes that cells undergo during carcinogenesis. [ 45 ] There is growing evidence that metabolic dependencies in cancer are influenced by tissue environment, being this important to consider the TME for different in vitro and in vivo models to study oncometabolism in different cancer scenarios. [ 46 ]
There is extensive research on the modulation of BET proteins in cancer models of breast. These proteins appear to be involved in oncometabolism and targeting and uncoupling BRD4 actions in carcinogenic cells, as well as stopping pro-migratory signals and changing cytokine metabolism, particularly IL-6 . [ 47 ] The same group has reported on the importance of exosomes in the TME and how these vesicles, shed by adipocytes , can carry a specific molecular cargo that causes metabolic changes in the cell, leading to pro-metastatic changes in the recipient breast cancer cells. [ 48 ] | https://en.wikipedia.org/wiki/Oncometabolism |
Oncotherm medical devices are produced by Oncotherm Ltd. and used for cancer treatment.
The company's methodology is based on the view of its founder that the heat-dose sensitive characterization of tissue is at the core of the oncothermia treatment. [ 1 ] The tumor tissue has lower impedance than the surrounding tissues, [ citation needed ] so most of the energy is transmitted and absorbed by the cancerous lesion. This selection of the tumor tissues (self-focusing) renders external focusing unnecessary. [ 2 ]
Oncotherm Ltd. was founded in 1988 by Prof. Dr. András Szász [ 3 ] in Hungary . In 2002, it received investment from a German company and was reorganized as a German-Hungarian company consisting of Oncotherm Hungary Ltd [ 4 ] and Oncotherm GmbH. [ 5 ]
Their main products are the Oncotherm EHY-2000 [ 6 ] and the Oncotherm EHY-2030, [ 7 ] hyperthermia devices using the thermoelectric effects of electrical fields .
More than 450 devices have been placed into operation, mostly in Germany and South Korea , and performed over 400,000 treatments. [ 8 ] The devices are not approved by the U.S. Food and Drug Administration . [ citation needed ]
This oncology article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Oncotherm |
Oncotic pressure , or colloid osmotic-pressure , is a type of osmotic pressure induced by the plasma proteins , notably albumin , [ 1 ] in a blood vessel's plasma (or any other body fluid such as blood and lymph ) that causes a pull on fluid back into the capillary.
It has an effect opposing both the hydrostatic blood pressure , which pushes water and small molecules out of the blood into the interstitial spaces at the arterial end of capillaries, and the interstitial colloidal osmotic pressure. These interacting factors determine the partitioning of extracellular water between the blood plasma and the extravascular space.
Oncotic pressure strongly affects the physiological function of the circulatory system. It is suspected to have a major effect on the pressure across the glomerular filter. However, this concept has been strongly criticised and attention has shifted to the impact of the intravascular glycocalyx layer as the major player. [ 2 ] [ 3 ] [ 4 ] [ 5 ]
The word 'oncotic' by definition is termed as 'pertaining to swelling', indicating the effect of oncotic imbalance on the swelling of tissues.
The word itself is derived from onco- and -ic; 'onco-' meaning 'pertaining to mass or tumors' and '-ic', which forms an adjective.
Throughout the body, dissolved compounds have an osmotic pressure. Because large plasma proteins cannot easily cross through the capillary walls, their effect on the osmotic pressure of the capillary interiors will, to some extent, balance out the tendency for fluid to leak out of the capillaries. In other words, the oncotic pressure tends to pull fluid into the capillaries. In conditions where plasma proteins are reduced, e.g. from being lost in the urine ( proteinuria ), there will be a reduction in oncotic pressure and an increase in filtration across the capillary, resulting in excess fluid buildup in the tissues ( edema ).
The large majority of oncotic pressure in capillaries is generated by the presence of high quantities of albumin , a protein that constitutes approximately 80% of the total oncotic pressure exerted by blood plasma on interstitial fluid [ citation needed ] . The total oncotic pressure of an average capillary is about 28 mmHg with albumin contributing approximately 22 mmHg of this oncotic pressure, despite only representing 50% of all protein in blood plasma at 35-50 g/L. [ 6 ] [ 7 ] Because blood proteins cannot escape through capillary endothelium, oncotic pressure of capillary beds tends to draw water into the vessels. It is necessary to understand the oncotic pressure as a balance; because the blood proteins reduce interior permeability, less plasma fluid can exit the vessel. [ 7 ]
Oncotic pressure is represented by the symbol Π or π in the Starling equation and elsewhere. The Starling equation in particular describes filtration in volume/s ( J v {\displaystyle J_{\mathrm {v} }} ) by relating oncotic pressure ( π p {\displaystyle \pi _{\mathrm {p} }} ) to capillary hydrostatic pressure ( P c {\displaystyle P_{\mathrm {c} }} ), interstitial fluid hydrostatic pressure ( P i {\displaystyle P_{\mathrm {i} }} ), and interstitial fluid oncotic pressure ( π i {\displaystyle \pi _{\mathrm {i} }} ), as well as several descriptive coefficients, as shown below:
J v = L p S ( [ P c − P i ] − σ [ π p − π i ] ) {\displaystyle \ J_{\mathrm {v} }=L_{\mathrm {p} }S([P_{\mathrm {c} }-P_{\mathrm {i} }]-\sigma [\pi _{\mathrm {p} }-\pi _{\mathrm {i} }])}
At the arteriolar end of the capillary, blood pressure starts at about 36 mm Hg and decreases to around 15 mm Hg at the venous end, with oncotic pressure at a stable 25–28 mm Hg. Within the capillary, reabsorption due to this venous pressure difference is estimated to be around 90% that of the filtered fluid, with the extra 10% being returned via lymphatics in order to maintain stable blood volume. [ 8 ]
In tissues, physiological disruption can arise with decreased oncotic pressure, which can be determined using blood tests for protein concentration.
Decreased colloidal osmotic pressure, most notably seen in hypoalbuminemia , can cause edema and decrease in blood volume as fluid is not reabsorbed into the bloodstream. Colloid pressure in these cases can be lost due to a number of different factors, but primarily decreased colloid production or increased loss of colloids through glomerular filtration. [ 6 ] [ 9 ] This low pressure often correlates with poor surgical outcomes. [ 10 ]
In the clinical setting, there are two types of fluids that are used for intravenous drips: crystalloids and colloids . Crystalloids are aqueous solutions of mineral salts or other water-soluble molecules. Colloids contain larger insoluble molecules, such as gelatin . There is some debate concerning the advantages and disadvantages of using biological vs. synthetic colloid solutions. [ 11 ] Oncotic pressure values are approximately 290 mOsm per kg of water, which slightly differs from the osmotic pressure of the blood that has values approximating 300 mOsm /L. [ citation needed ] These colloidal solutions are typically used to remedy low colloid concentration, such as in hypoalbuminemia, but is also suspected to assist in injuries that typically increase fluid loss, such as burns. [ 12 ] | https://en.wikipedia.org/wiki/Oncotic_pressure |
An oncovirus or oncogenic virus is a virus that can cause cancer . [ 4 ] This term originated from studies of acutely transforming retroviruses in the 1950–60s, [ 5 ] when the term oncornaviruses was used to denote their RNA virus origin. [ 6 ] With the letters RNA removed, it now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with tumor virus or cancer virus . The vast majority of human and animal viruses do not cause cancer, probably because of longstanding co-evolution between the virus and its host. Oncoviruses have been important not only in epidemiology , but also in investigations of cell cycle control mechanisms such as the retinoblastoma protein .
The World Health Organization 's International Agency for Research on Cancer estimated that in 2002, infection caused 17.8% of human cancers, with 11.9% caused by one of seven viruses. [ 7 ] A 2020 study of 2,658 samples from 38 different types of cancer found that 16% were associated with a virus. [ 8 ] These cancers might be easily prevented through vaccination (e.g., papillomavirus vaccines ), diagnosed with simple blood tests, and treated with less-toxic antiviral compounds.
Generally, tumor viruses cause little or no disease after infection in their hosts, or cause non- neoplastic diseases such as acute hepatitis for hepatitis B virus or mononucleosis for Epstein–Barr virus . A minority of persons (or animals) will go on to develop cancers after infection. This has complicated efforts to determine whether or not a given virus causes cancer. The well-known Koch's postulates , 19th-century constructs developed by Robert Koch to establish the likelihood that Bacillus anthracis will cause anthrax disease, are not applicable to viral diseases. Firstly, this is because viruses cannot truly be isolated in pure culture—even stringent isolation techniques cannot exclude undetected contaminating viruses with similar density characteristics, and viruses must be grown on cells. Secondly, asymptomatic virus infection and carriage is the norm for most tumor viruses, which violates Koch's third principle. Relman and Fredericks have described the difficulties in applying Koch's postulates to virus-induced cancers. [ 9 ] Finally, the host restriction for human viruses makes it unethical to experimentally transmit a suspected cancer virus. Other measures, such as A. B. Hill's criteria , [ 10 ] are more relevant to cancer virology but also have some limitations in determining causality.
Tumor viruses come in a variety of forms: Viruses with a DNA genome , such as adenovirus , and viruses with an RNA genome, like the hepatitis C virus (HCV), can cause cancers, as can retroviruses having both DNA and RNA genomes ( Human T-lymphotropic virus and hepatitis B virus , which normally replicates as a mixed double and single-stranded DNA virus but also has a retroviral replication component). In many cases, tumor viruses do not cause cancer in their native hosts but only in dead-end species. For example, adenoviruses do not cause cancer in humans but are instead responsible for colds, conjunctivitis and other acute illnesses. They only become tumorigenic when infected into certain rodent species, such as Syrian hamsters. Some viruses are tumorigenic when they infect a cell and persist as circular episomes or plasmids, replicating separately from host cell DNA ( Epstein–Barr virus and Kaposi's sarcoma-associated herpesvirus ). Other viruses are only carcinogenic when they integrate into the host cell genome as part of a biological accident, such as polyomaviruses and papillomaviruses. [ citation needed ]
A direct oncogenic viral mechanism [ 11 ] involves either insertion of additional viral oncogenic genes into the host cell or to enhance already existing oncogenic genes ( proto-oncogenes ) in the genome. For example, it has been shown that vFLIP and vCyclin interfere with the TGF-β signaling pathway indirectly by inducing oncogenic host mir17-92 cluster. [ 12 ]
Indirect viral oncogenicity involves chronic nonspecific inflammation occurring over decades of infection, as is the case for HCV-induced liver cancer. These two mechanisms differ in their biology and epidemiology: direct tumor viruses must have at least one virus copy in every tumor cell expressing at least one protein or RNA that is causing the cell to become cancerous. Because foreign virus antigens are expressed in these tumors, persons who are immunosuppressed such as AIDS or transplant patients are at higher risk for these types of cancers. [ citation needed ]
Chronic indirect tumor viruses, on the other hand, can be lost (at least theoretically) from a mature tumor that has accumulated sufficient mutations and growth conditions (hyperplasia) from the chronic inflammation of viral infection. In this latter case, it is controversial but at least theoretically possible that an indirect tumor virus could undergo "hit-and-run" and so the virus would be lost from the clinically diagnosed tumor. In practical terms, this is an uncommon occurrence if it does occur. [ citation needed ]
DNA oncoviruses typically impair two families of tumor suppressor proteins: tumor proteins p53 and the retinoblastoma proteins (Rb). It is evolutionarily advantageous for viruses to inactivate p53 because p53 can trigger cell cycle arrest or apoptosis in infected cells when the virus attempts to replicate its DNA. [ 13 ] Similarly, Rb proteins regulate many essential cell functions, including but not limited to a crucial cell cycle checkpoint, making them a target for viruses attempting to interrupt regular cell function. [ 14 ]
While several DNA oncoviruses have been discovered, three have been studied extensively. Adenoviruses can lead to tumors in rodent models but do not cause cancer in humans; however, they have been exploited as delivery vehicles in gene therapy for diseases such as cystic fibrosis and cancer. [ 15 ] Simian virus 40 (SV40), a polyomavirus , can cause tumors in rodent models but is not oncogenic in humans. [ 16 ] This phenomenon has been one of the major controversies of oncogenesis in the 20th century because an estimated 100 million people were inadvertently exposed to SV40 through polio vaccines. [ 16 ] The human papillomavirus -16 (HPV-16) has been shown to lead to cervical cancer and other cancers, including head and neck cancer. [ 17 ] These three viruses have parallel mechanisms of action, forming an archetype for DNA oncoviruses. All three of these DNA oncoviruses are able to integrate their DNA into the host cell, and use this to transcribe it and transform cells by bypassing the G1/S checkpoint of the cell cycle. [ citation needed ]
DNA oncoviruses transform infected cells by integrating their DNA into the host cell's genome. [ 18 ] The DNA is believed to be inserted during transcription or replication, when the two annealed strands are separated. [ 18 ] This event is relatively rare and generally unpredictable; there seems to be no deterministic predictor of the site of integration. [ 18 ] After integration, the host's cell cycle loses regulation from Rb and p53, and the cell begins cloning to form a tumor. [ 19 ]
Rb and p53 regulate the transition between G1 and S phase , arresting the cell cycle before DNA replication until the appropriate checkpoint inputs, such as DNA damage repair, are completed. [ 20 ] p53 regulates the p21 gene, which produces a protein which binds to the Cyclin D-Cdk4/6 complex. [ 21 ] This prevents Rb phosphorylation and prevents the cell from entering S phase. [ 21 ] In mammals, when Rb is active (unphosphorylated), it inhibits the E2F family of transcription factors, which regulate the Cyclin E - Cdk2 complex, which inhibits Rb, forming a positive feedback loop, keeping the cell in G1 until the input crosses a threshold. [ 20 ] To drive the cell into S phase prematurely, the viruses must inactivate p53, which plays a central role in the G1/S checkpoint, as well as Rb, which, though downstream of it, is typically kept active by a positive feedback loop. [ citation needed ]
Viruses employ various methods of inactivating p53. The adenovirus E1B protein (55K) prevents p53 from regulating genes by binding to the site on p53 which binds to the genome. [ 13 ] In SV40, the large T antigen (LT) is an analogue; LT also binds to several other cellular proteins, such as p107 and p130 , on the same residues. [ 22 ] LT binds to p53's binding domain on the DNA (rather than on the protein), again preventing p53 from appropriately regulating genes. [ 13 ] HPV instead degrades p53: the HPV protein E6 binds to a cellular protein called the E6-associated protein (E6-AP, also known as UBE3A ), forming a complex which causes the rapid and specific ubiquitination of p53. [ 23 ]
Rb is inactivated (thereby allowing the G1/S transition to progress unimpeded) by different but analogous viral oncoproteins. The adenovirus early region 1A (E1A) is an oncoprotein which binds to Rb and can stimulate transcription and transform cells. [ 13 ] SV40 uses the same protein for inactivating Rb, LT, to inactivate p53. [ 21 ] HPV contains a protein, E7, which can bind to Rb in much the same way. [ 24 ] Rb can be inactivated by phosphorylation, or by being bound to a viral oncoprotein, or by mutations—mutations which prevent oncoprotein binding are also associated with cancer. [ 22 ]
DNA oncoviruses typically cause cancer by inactivating p53 and Rb, thereby allowing unregulated cell division and creating tumors. There may be many different mechanisms which have evolved separately; in addition to those described above, for example, the Human Papillomavirus inactivates p53 by sequestering it in the cytoplasm. [ 13 ]
SV40 has been well studied and does not cause cancer in humans, but a recently discovered analogue called Merkel cell polyomavirus has been associated with Merkel cell carcinoma , a form of skin cancer. [ 25 ] The Rb binding feature is believed to be the same between the two viruses. [ 25 ]
In the 1960s, the replication process of RNA virus was believed to be similar to other single-stranded RNA. Single-stranded RNA replication involves RNA-dependent RNA synthesis which meant that virus-coding enzymes would make partial double-stranded RNA. This belief was shown to be incorrect because there were no double-stranded RNA found in the retrovirus cell. In 1964, Howard Temin proposed a provirus hypothesis, but shortly after reverse transcription in the retrovirus genome was discovered. [ 26 ]
All retroviruses have three major coding domains; gag , pol and env . In the gag region of the virus, the synthesis of the internal virion proteins are maintained which make up the matrix, capsid and nucleocapsid proteins. In pol , the information for the reverse transcription and integration enzymes are stored. In env , it is derived from the surface and transmembrane for the viral envelope protein. There is a fourth coding domain which is smaller, but exists in all retroviruses. Pol is the domain that encodes the virion protease.
The retrovirus begins the journey into a host cell by attaching a surface glycoprotein to the cell's plasma membrane receptor. Once inside the cell, the retrovirus goes through reverse transcription in the cytoplasm and generates a double-stranded DNA copy of the RNA genome. Reverse transcription also produces identical structures known as long terminal repeats (LTRs). Long terminal repeats are at the ends of the DNA strands and regulates viral gene expression. The viral DNA is then translocated into the nucleus where one strand of the retroviral genome is put into the chromosomal DNA by the help of the virion integrase. At this point the retrovirus is referred to as provirus. Once in the chromosomal DNA, the provirus is transcribed by the cellular RNA polymerase II. The transcription leads to the splicing and full-length mRNAs and full-length progeny virion RNA. The virion protein and progeny RNA assemble in the cytoplasm and leave the cell, whereas the other copies send translated viral messages in the cytoplasm.
Not all oncoviruses are DNA viruses . Some RNA viruses have also been associated such as the hepatitis C virus as well as certain retroviruses, e.g., human T-lymphotropic virus (HTLV-1) and Rous sarcoma virus (RSV).
Estimated percent of new cancers attributable to the virus worldwide in 2002. [ 7 ] NA indicates not available. The association of other viruses with human cancer is continually under research.
The main viruses associated with human cancers are the human papillomavirus , the hepatitis B and hepatitis C viruses, the Epstein–Barr virus , the human T-lymphotropic virus , the Kaposi's sarcoma-associated herpesvirus (KSHV) and the Merkel cell polyomavirus . Experimental and epidemiological data imply a causative role for viruses and they appear to be the second most important risk factor for cancer development in humans, exceeded only by tobacco usage. [ 42 ] The mode of virally induced tumors can be divided into two, acutely transforming or slowly transforming . In acutely transforming viruses, the viral particles carry a gene that encodes for an overactive oncogene called viral-oncogene (v-onc), and the infected cell is transformed as soon as v-onc is expressed. In contrast, in slowly transforming viruses, the virus genome is inserted, especially as viral genome insertion is an obligatory part of retroviruses , near a proto-oncogene in the host genome. The viral promoter or other transcription regulation elements in turn cause overexpression of that proto-oncogene, which in turn induces uncontrolled cellular proliferation. Because viral genome insertion is not specific to proto-oncogenes and the chance of insertion near that proto-oncogene is low, slowly transforming viruses have very long tumor latency compared to acutely transforming viruses, which already carry the viral oncogene. [ citation needed ]
Hepatitis viruses, including hepatitis B and hepatitis C , can induce a chronic viral infection that leads to liver cancer in 0.47% of hepatitis B patients per year (especially in Asia, less so in North America), and in 1.4% of hepatitis C carriers per year. Liver cirrhosis, whether from chronic viral hepatitis infection or alcoholism, is associated with the development of liver cancer, and the combination of cirrhosis and viral hepatitis presents the highest risk of liver cancer development. Worldwide, liver cancer is one of the most common, and most deadly, cancers due to a huge burden of viral hepatitis transmission and disease. [ citation needed ]
Through advances in cancer research, vaccines designed to prevent cancer have been created. The hepatitis B vaccine is the first vaccine that has been established to prevent cancer ( hepatocellular carcinoma ) by preventing infection with the causative virus. In 2006, the U.S. Food and Drug Administration approved a human papilloma virus vaccine, called Gardasil . The vaccine protects against four HPV types, which together cause 70% of cervical cancers and 90% of genital warts. In March 2007, the US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) officially recommended that females aged 11–12 receive the vaccine, and indicated that females as young as age 9 and as old as age 26 are also candidates for immunization. [ citation needed ]
The history of cancer virus discovery is intertwined with the history of cancer research and the history of virology . The oldest surviving record of a human cancer is the Babylonian Code of Hammurabi (dated ca. 1754 BC) but scientific oncology could only emerge in the 19th century, when tumors were studied at microscopic level with the help of the compound microscope and achromatic lenses . 19th century microbiology accumulated evidence that implicated bacteria, yeasts , fungi, and protozoa in the development of cancer. In 1926 the Nobel Prize was awarded for documenting that a nematode worm could provoke stomach cancer in rats. But it was not recognized that cancer could have infectious origins until much later as virus had first been discovered by Dmitri Ivanovsky and Martinus Beijerinck at the close of the 19th century. [ 43 ]
The theory that cancer could be caused by a virus began with the experiments of Oluf Bang and Vilhelm Ellerman in 1908 at the University of Copenhagen . Bang and Ellerman demonstrated that avian sarcoma leukosis virus could be transmitted between chickens after cell-free filtration and subsequently cause leukemia. [ 44 ] [ 45 ] This was subsequently confirmed for solid tumors in chickens in 1910–1911 by Peyton Rous . [ 46 ] [ 47 ] Rous at the Rockefeller University extended Bang and Ellerman's experiments to show cell-free transmission of a solid tumor sarcoma to chickens (now known as Rous sarcoma ). The reasons why chickens are so receptive to such transmission may involve unusual characteristics of stability or instability as they relate to endogenous retroviruses . [ 47 ] [ 48 ] Charlotte Friend confirmed Bang and Ellerman findings for liquid tumor in mice by . [ 49 ] In 1933 Richard Shope and Edward Weston Hurst showed that warts from wild cottontail rabbits contained the Shope papilloma virus . [ 43 ] In 1936 John Joseph Bittner identified the mouse mammary tumor virus , an "extrachromosomal factor" (i.e. virus) that could be transmitted between laboratory strains of mice by breast feeding. [ 50 ]
By the early 1950s, it was known that viruses could remove and incorporate genes and genetic material in cells. It was suggested that such types of viruses could cause cancer by introducing new genes into the genome. Genetic analysis of mice infected with Friend virus confirmed that retroviral integration could disrupt tumor suppressor genes, causing cancer. [ 51 ] Viral oncogenes were subsequently discovered and identified to cause cancer. [ citation needed ] Ludwik Gross identified the first mouse leukemia virus ( murine leukemia virus ) in 1951 [ 43 ] and in 1953 reported on a component of mouse leukemia extract capable of causing solid tumors in mice. [ 52 ] This compound was subsequently identified as a virus by Sarah Stewart and Bernice Eddy at the National Cancer Institute , after whom it was once called "SE polyoma". [ 53 ] [ 54 ] [ 55 ] In 1957 Charlotte Friend discovered the Friend virus , a strain of murine leukemia virus capable of causing cancers in immunocompetent mice. [ 49 ] Though her findings received significant backlash, they were eventually accepted by the field and cemented the validity of viral oncogenesis. [ 56 ]
In 1961 Eddy discovered the simian vacuolating virus 40 ( SV40 ). Merck Laboratory also confirmed the existence of a rhesus macaque virus contaminating cells used to make Salk and Sabin polio vaccines . Several years later, it was shown to cause cancer in Syrian hamsters , raising concern about possible human health implications. Scientific consensus now strongly agrees that this is not likely to cause human cancer. [ 57 ] [ 58 ]
In 1964 Anthony Epstein , Bert Achong and Yvonne Barr identified the first human oncovirus from Burkitt's lymphoma cells. A herpesvirus, this virus is formally known as human herpesvirus 4 but more commonly called Epstein–Barr virus or EBV. [ 59 ] In the mid-1960s Baruch Blumberg first physically isolated and characterized Hepatitis B while working at the National Institute of Health (NIH) and later the Fox Chase Cancer Center . [ 60 ] Although this agent was the clear cause of hepatitis and might contribute to liver cancer hepatocellular carcinoma , this link was not firmly established until epidemiologic studies were performed in the 1980s by R. Palmer Beasley and others. [ 61 ]
In 1980 the first human retrovirus, Human T-lymphotropic virus 1 (HTLV-I), was discovered by Bernard Poiesz and Robert Gallo at NIH, [ 62 ] [ 63 ] and independently by Mitsuaki Yoshida and coworkers in Japan. [ 64 ] But it was not certain whether HTLV-I promoted leukemia. In 1981 Yorio Hinuma and his colleagues at Kyoto University reported visualization of retroviral particles produced by a leukemia cell line derived from patients with Adult T-cell leukemia/lymphoma . This virus turned out to be HTLV-1 and the research established the causal role of the HTLV-1 virus to ATL. [ 43 ]
Between 1984 and 1986 Harald zur Hausen and Lutz Gissmann discovered HPV16 and HPV18, together these Papillomaviridae viruses (HPV) are responsible for approximately 70% of human papillomavirus infections that cause cervical cancers . For the discovery that HPV cause human cancer the 2008 Nobel Prize was awarded. [ 65 ] In 1987 the Hepatitis C virus (HCV) was discovered by panning a cDNA library made from diseased tissues for foreign antigens recognized by patient sera. This work was performed by Michael Houghton at Chiron , a biotechnology company, and Daniel W. Bradley at the Centers for Disease Control and Prevention (CDC). [ 66 ] HCV was subsequently shown to be a major contributor to Hepatocellular carcinoma (liver cancer) worldwide. [ 43 ]
In 1994 Patrick S. Moore and Yuan Chang at Columbia University ), working together with Ethel Cesarman , [ 67 ] [ 68 ] isolated Kaposi's sarcoma-associated herpesvirus (KSHV or HHV8) using representational difference analysis . This search was prompted by work from Valerie Beral and colleagues who inferred from the epidemic of Kaposi's sarcoma among patients with AIDS that this cancer must be caused by another infectious agent besides HIV, and that this was likely to be a second virus. [ 69 ] Subsequent studies revealed that KSHV is the "KS agent" and is responsible for the epidemiologic patterns of KS and related cancers. [ 70 ]
In 2008 Yuan Chang and Patrick S. Moore developed a new method to identify cancer viruses based on computer subtraction of human sequences from a tumor transcriptome , called digital transcriptome subtraction (DTS). [ 71 ] DTS was used to isolate DNA fragments of Merkel cell polyomavirus from a Merkel cell carcinoma and it is now believed that this virus causes 70–80% of these cancers. [ 25 ] | https://en.wikipedia.org/wiki/Oncovirus |
ONE-NET is an open-source standard for wireless networking . [ 1 ] ONE-NET (not to be confused with NMEA OneNet ) was designed for low-cost, low-power (battery-operated) control networks for applications such as home automation, security & monitoring, device control, and sensor networks. ONE-NET is not tied to any proprietary hardware or software, and can be implemented with a variety of low-cost off-the-shelf radio transceivers and micro controllers from a number of different manufacturers. [ 2 ]
ONE-NET uses UHF ISM radio transceivers and currently operates in the 868 MHz and 915 MHz frequencies with 25 channels available for use in the United States. The ONE-NET standard allows for implementation on other frequencies, and some work is being done to implement it in the 433 MHz and 2.4 GHz frequency ranges.
ONE-NET utilizes Wideband FSK ( Frequency-shift keying ) to encode data for transmission.
ONE-NET features a dynamic data rate protocol with a base data rate of 38.4 kbit/s. The specification allows per-node dynamic data rate configuration for data rates up to 230 kbit/s.
ONE-NET supports star, peer-to-peer and multi-hop topology. Star network topology can be used to lower complexity and cost of peripherals, and also simplifies encryption key management. In peer-to-peer mode, a master device configures and authorizes peer-to-peer transactions. Employing repeaters and a configurable repetition radius multi-hop mode allows to cover larger areas or route around dead areas. Mesh routing is not supported.
Outdoor peer-to-peer range has been measured to over 500 m, indoor peer-to-peer range has been demonstrated from 60 m to over 100 m, and mesh mode can extend operational range to several kilometers.
Simple, block, and streaming transactions are supported.
Simple transactions typically use message types as defined by the ONE-NET protocol to exchange sensor data such as temperature or energy consumption, and control data such as on/off messages. Simple transactions use encryption techniques to avoid susceptibility to replay attacks.
Block transactions can be used to transmit larger blocks of data than simple messages. Block transactions consist of multiple packets containing up to 58 bytes per packet. Blocks transactions can transfer up to 65,535 bytes per block.
Streaming transactions are similar in format to block transactions but do not require retransmission of lost data packets.
ONE-NET is optimized for low power consumption such as battery-powered peripherals. Low-duty-cycle battery-powered ONE-NET devices such as window sensors, moisture detectors, etc. can achieve a three to five year battery life with “AA” or "AAA" alkaline cells.
Dynamic power adjustment allows signal strength info to be used to scale back transmit power to conserve battery power. High data rates and short packet sizes minimize Transceiver On time. Further power efficiency can be gained utilizing deterministic sleep periods for client devices.
By default, ONE-NET uses the Extended Tiny Encryption Algorithm ( XTEA ) version 2 with 32 iterations (XTEA2-32). The ONE-NET protocol provides extensions to even higher levels of encryption. Encryption is integral to the ONE-NET protocol, there are no unencrypted modes. Alternate encryption ID tag allows extension to stronger algorithms.
ONE-NET helps resist a spoofing attack or replay attack by using embedded nonces to ensure unique packets. Cryptographic nonce tracking allows source verification.
Security key update rate can be set on a per-system basis to allow greater control of security level - faster key updates increase network security.
Programmable “still operational” messages can be used to detect sensor tampering or device failure.
ONE-NET works on a number of transceivers from manufacturers such as TI, Analog Devices, Semtech, RFM, Integration and Micrel. Transceivers that have been tested as working with ONE-NET include:
Simple ONE-NET devices such as motion sensors have modest host processor requirements:
ONE-NET is well-suited for low-cost 8-bit and 16-bit processors and has been tested with the TI MSP430 , Renesas R8C , C8051, and Freescale 68HC08 (HC08).
ONE-NET is available to use for free using an open source license. ONE-NET uses the OSI-approved “Simplified BSD License” which is one of the so-called permissive free software licenses .
ONE-NET website provides a variety of open source community-supported resources including:
A number of companies have announced support for the ONE-NET open source initiative including: | https://en.wikipedia.org/wiki/One-Net |
A one-bit message is a type of communication that has no personalized or specified content, and as such transmits only a single binary bit of information. It signals an intent and a thought, but does not specify what it is. Marc Andreessen describes "one-bit communication" as having no content other than that it exists. [ 1 ] Examples of one-bit messages in the real world include the sound of a car horn, a police siren, [ 1 ] and an "open" sign on a retail store. [ 1 ] Telephone calls which are deliberately terminated before being answered are also an example of one-bit communication.
One-bit messages can be used to communicate the outcome of situations with two potential outcomes, such as a coin toss. [ 2 ] [ disputed – discuss ]
In the online world, one-bit messages solve a set of communication initiative problems: [ citation needed ]
There are several platforms that enable sending one-bit messages including Yo and the Facebook poke . | https://en.wikipedia.org/wiki/One-bit_message |
One-compartment kinetics for a chemical compound specifies that the uptake in the compartment is proportional to the concentration outside the compartment, and the elimination is proportional to the concentration inside the compartment. Both the compartment and the environment outside the compartment are considered to be homogeneous (well mixed).The compartment typically represents some organism (e.g. a fish or a daphnid ).
This model is used in the simplest versions of the DEBtox method for the quantification of effects of toxicants.
This biochemistry article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/One-compartment_kinetics |
A one-dimensional symmetry group is a mathematical group that describes symmetries in one dimension (1D).
A pattern in 1D can be represented as a function f ( x ) for, say, the color at position x .
The only nontrivial point group in 1D is a simple reflection . It can be represented by the simplest Coxeter group , A 1 , [ ], or Coxeter-Dynkin diagram .
Affine symmetry groups represent translation . Isometries which leave the function unchanged are translations x + a with a such that f ( x + a ) = f ( x ) and reflections a − x with a such that f ( a − x ) = f ( x ). The reflections can be represented by the affine Coxeter group [∞], or Coxeter-Dynkin diagram representing two reflections, and the translational symmetry as [∞] + , or Coxeter-Dynkin diagram as the composite of two reflections.
For a pattern without translational symmetry there are the following possibilities (1D point groups ):
These affine symmetries can be considered limiting cases of the 2D dihedral and cyclic groups :
Consider all patterns in 1D which have translational symmetry , i.e., functions f ( x ) such that for some a > 0, f ( x + a ) = f ( x ) for all x . For these patterns, the values of a for which this property holds form a group .
We first consider patterns for which the group is discrete , i.e., for which the positive values in the group have a minimum. By rescaling we make this minimum value 1.
Such patterns fall in two categories, the two 1D space groups or line groups .
In the simpler case the only isometries of R which map the pattern to itself are translations; this applies, e.g., for the pattern
Each isometry can be characterized by an integer, namely plus or minus the translation distance. Therefore the symmetry group is Z .
In the other case, among the isometries of R which map the pattern to itself there are also reflections; this applies, e.g., for the pattern
We choose the origin for x at one of the points of reflection. Now all reflections which map the pattern to itself are of the form a − x where the constant " a " is an integer (the increments of a are 1 again, because we can combine a reflection and a translation to get another reflection, and we can combine two reflections to get a translation). Therefore all isometries can be characterized by an integer and a code, say 0 or 1, for translation or reflection.
Thus:
The latter is a reflection with respect to the point a /2 (an integer or an integer plus 1/2).
Group operations ( function composition , the one on the right first) are, for integers a and b :
E.g., in the third case: translation by an amount b changes x into x + b , reflection with respect to 0 gives− x − b , and a translation a gives a − b − x .
This group is called the generalized dihedral group of Z , Dih( Z ), and also D ∞ . It is a semidirect product of Z and C 2 . It has a normal subgroup of index 2 isomorphic to Z : the translations. Also it contains an element f of order 2 such that, for all n in Z , n f = f n −1 : the reflection with respect to the reference point, (0,1).
The two groups are called lattice groups . The lattice is Z . As translation cell we can take the interval 0 ≤ x < 1. In the first case the fundamental domain can be taken the same; topologically it is a circle (1- torus ); in the second case we can take 0 ≤ x ≤ 0.5.
The actual discrete symmetry group of a translationally symmetric pattern can be:
The set of translationally symmetric patterns can thus be classified by actual symmetry group, while actual symmetry groups, in turn, can be classified as type 1 or type 2.
These space group types are the symmetry groups “up to conjugacy with respect to affine transformations”: the affine transformation changes the translation distance to the standard one (above: 1), and the position of one of the points of reflections, if applicable, to the origin. Thus the actual symmetry group contains elements of the form gag −1 = b , which is a conjugate of a .
For a homogeneous “pattern” the symmetry group contains all translations, and reflection in all points. The symmetry group is isomorphic to Dih( R ).
There are also less trivial patterns/functions with translational symmetry for arbitrarily small translations, e.g. the group of translations by rational distances. Even apart from scaling and shifting, there are infinitely many cases, e.g. by considering rational numbers of which the denominators are powers of a given prime number.
The translations form a group of isometries. However, there is no pattern with this group as symmetry group.
Symmetries of a function (in the sense of this article) imply corresponding symmetries of its graph. However, 2-fold rotational symmetry of the graph does not imply any symmetry (in the sense of this article) of the function: function values (in a pattern representing colors, grey shades, etc.) are nominal data , i.e. grey is not between black and white, the three colors are simply all different.
Even with nominal colors there can be a special kind of symmetry, as in:
(reflection gives the negative image). This is also not included in the classification.
Group actions of the symmetry group that can be considered in this connection are:
This section illustrates group action concepts for these cases.
The action of G on X is called
Consider a group G acting on a set X . The orbit of a point x in X is the set of elements of X to which x can be moved by the elements of G . The orbit of x is denoted by Gx :
Case that the group action is on R :
Case that the group action is on patterns:
The set of all orbits of X under the action of G is written as X / G .
If Y is a subset of X , we write GY for the set { g · y : y ∈ {\displaystyle \in } Y and g ∈ {\displaystyle \in } G }. We call the subset Y invariant under G if GY = Y (which is equivalent to GY ⊆ Y ). In that case, G also operates on Y . The subset Y is called fixed under G if g · y = y for all g in G and all y in Y . In the example of the orbit {−8,−6,2,4,12,14,22,24,..}, {−9,−8,−6,−5,1,2,4,5,11,12,14,15,21,22,24,25,..} is invariant under G , but not fixed.
For every x in X , we define the stabilizer subgroup of x (also called the isotropy group or little group ) as the set of all elements in G that fix x :
If x is a reflection point, its stabilizer is the group of order two containing the identity and the reflection in x . In other cases the stabilizer is the trivial group.
For a fixed x in X , consider the map from G to X given by g ∣ → g ⋅ x {\displaystyle g\mid \rightarrow g\cdot x} . The image of this map is the orbit of x and the coimage is the set of all left cosets of G x . The standard quotient theorem of set theory then gives a natural bijection between G / G x {\displaystyle G/G_{x}} and G x {\displaystyle Gx} . Specifically, the bijection is given by h G x ∣ → h ⋅ x {\displaystyle hG_{x}\mid \rightarrow h\cdot x} . This result is known as the orbit-stabilizer theorem . If, in the example, we take x = 3 {\displaystyle x=3} , the orbit is {−7,3,13,23,..}, and the two groups are isomorphic with Z .
If two elements x {\displaystyle x} and y {\displaystyle y} belong to the same orbit, then their stabilizer subgroups, G x {\displaystyle G_{x}} and G y {\displaystyle G_{y}} , are isomorphic . More precisely: if y = g ⋅ x {\displaystyle y=g\cdot x} , then G y = g G x g − 1 {\displaystyle G_{y}=gG_{x}g^{-1}} . In the example this applies e.g. for 3 and 23, both reflection points. Reflection about 23 corresponds to a translation of −20, reflection about 3, and translation of 20. | https://en.wikipedia.org/wiki/One-dimensional_symmetry_group |
In chemistry a one-pot synthesis is a strategy to improve the efficiency of a chemical reaction in which a reactant is subjected to successive chemical reactions in just one reactor. This is much desired by chemists because avoiding a lengthy separation process and purification of the intermediate chemical compounds can save time and resources while increasing chemical yield .
An example of a one-pot synthesis is the total synthesis of tropinone or the Gassman indole synthesis . Sequential one-pot syntheses can be used to generate even complex targets with multiple stereocentres , such as oseltamivir , [ 1 ] which may significantly shorten the number of steps required overall and have important commercial implications.
A sequential one-pot synthesis with reagents added to a reactor one at a time and without work-up is also called a telescoping synthesis .
In one such procedure [ 2 ] the reaction of 3-N-tosylaminophenol I with acrolein II affords a hydroxyl substituted quinoline III through 4 sequential steps without workup of the intermediate products (see image). The addition of acrolein (blue) is a Michael reaction catalyzed by N,N-diisopropylamine , the presence of ethanol converts the aldehyde group to an acetal but this process is reversed when hydrochloric acid is introduced (red). The enolate reacts as an electrophile in a Friedel-Crafts reaction with ring-closure. The alcohol group is eliminated in presence of potassium hydroxide (green) and when in the final step the reaction medium is neutralized to pH 7 (magenta) the tosyl group is eliminated as well.
This chemical reaction article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/One-pot_synthesis |
In plane geometry , a triangle ABC contains a triangle having one-seventh of the area of ABC , which is formed as follows: the sides of this triangle lie on cevians p, q, r where
The proof of the existence of the one-seventh area triangle follows from the construction of six parallel lines:
The suggestion of Hugo Steinhaus is that the (central) triangle with sides p,q,r be reflected in its sides and vertices. [ 1 ] These six extra triangles partially cover ABC , and leave six overhanging extra triangles lying outside ABC . Focusing on the parallelism of the full construction (offered by Martin Gardner through James Randi ’s on-line magazine), the pair-wise congruences of overhanging and missing pieces of ABC is evident. As seen in the graphical solution, six plus the original equals the whole triangle ABC . [ 2 ]
An early exhibit of this geometrical construction and area computation was given by Robert Potts in 1859 in his Euclidean geometry textbook. [ 3 ]
According to Cook and Wood (2004), this triangle puzzled Richard Feynman in a dinner conversation; they go on to give four different proofs. [ 4 ]
A more general result is known as Routh's theorem . Also see Marion Walter ’s theorem. | https://en.wikipedia.org/wiki/One-seventh_area_triangle |
In game theory , the one-shot deviation principle (also known as the single-deviation property [ 1 ] ) is a principle used to determine whether a strategy in a sequential game constitutes a subgame perfect equilibrium [ 2 ] . An SPE is a Nash equilibrium where no player has an incentive to deviate in any subgame. It is closely related to the principle of optimality in dynamic programming . [ 2 ]
The one-shot deviation principle states that a strategy profile of a finite multi-stage extensive-form game with observed actions is an SPE if and only if there exist no profitable single deviation for each subgame and every player. [ 1 ] [ 3 ] In simpler terms, if no player can profit (increase their expected payoff) by deviating from their original strategy via a single action (in just one stage of the game), then the strategy profile is an SPE.
The one-shot deviation principle is very important for infinite horizon games, in which the backward induction method typically doesn't work to find SPE. In an infinite horizon game where the discount factor is less than 1, a strategy profile is a subgame perfect equilibrium if and only if it satisfies the one-shot deviation principle. [ 4 ]
The following is the paraphrased definition from Watson (2013). [ 1 ]
To check whether strategy s is a subgame perfect Nash equilibrium, we have to ask every player i and every subgame, if considering s , there is a strategy s’ that yields a strictly higher payoff for player i than does s in the subgame. In a finite multi-stage game with observed actions, this analysis is equivalent to looking at single deviations from s , meaning s’ differs from s at only one information set (in a single stage). Note that the choices associated with s and s’ are the same at all nodes that are successors of nodes in the information set where s and s’ prescribe different actions.
Consider a symmetric game with two players in which each player makes binary choice decisions, A or B, in each of three stages. In each stage, the players observe the choices made in the previous stages (if any). Note that each player has 21 information sets, one in the first stage, four in the second stage (because players observe the outcome of the first stage, one of four action combinations), and 16 in the third stage (4 times 4 histories of action combinations from the first two stages). The single-deviation condition requires checking each of these information sets, asking in each case whether the expected payoff of the player on the move would strictly increase by deviating at only this information set. | https://en.wikipedia.org/wiki/One-shot_deviation_principle |
In numerical mathematics , one-step methods and multi-step methods are a large group of calculation methods for solving initial value problems . This problem, in which an ordinary differential equation is given together with an initial condition, plays a central role in all natural and engineering sciences and is also becoming increasingly important in the economic and social sciences , for example. Initial value problems are used to analyze, simulate or predict dynamic processes.
The basic idea behind one-step methods is that they calculate approximation points step by step along the desired solution, starting from the given starting point. They only use the most recently determined approximation for the next step, in contrast to multi-step methods, which also include points further back in the calculation. The one-step methods can be roughly divided into two groups: the explicit methods, which calculate the new approximation directly from the old one, and the implicit methods, which require an equation to be solved. The latter are also suitable for so-called stiff initial value problems.
The simplest and oldest one-step method, the explicit Euler method, was published by Leonhard Euler in 1768. After a group of multi-step methods was presented in 1883, Carl Runge , Karl Heun and Wilhelm Kutta developed significant improvements to Euler's method around 1900. These gave rise to the large group of Runge-Kutta methods, which form the most important class of one-step methods. Further developments in the 20th century include the idea of extrapolation and, above all, considerations on step width control, i.e. the selection of suitable lengths for the individual steps of a method. These concepts form the basis for solving difficult initial value problems, as they occur in modern applications, efficiently and with the required accuracy using computer programs.
The development of differential and integral calculus by the English physicist and mathematician Isaac Newton and, independently of this, by the German polymath Gottfried Wilhelm Leibniz in the last third of the 17th century was a major impetus for the mathematization of science in the early modern period. These methods formed the starting point of the mathematical subfield of analysis and are of central importance in all natural and engineering sciences. While Leibniz was led to differential calculus by the geometric problem of determining tangents to given curves, Newton started from the question of how changes in a physical quantity can be determined at a specific point in time. [ 1 ]
For example, when a body moves, its average speed is simply the distance traveled divided by the time required to travel it. However, in order to mathematically formulate the instantaneous velocity v ( t ) {\textstyle v(t)} of the body at a certain point in time t {\displaystyle t} , a limit transition is necessary: Consider short time spans of length Δ t {\displaystyle \Delta t} , the distances traveled Δ x {\displaystyle \Delta x} and the corresponding average velocities Δ x Δ t {\displaystyle {\tfrac {\Delta x}{\Delta t}}} .If the time period Δ 𝑡 is now allowed to converge towards zero and if the average velocities also approach a fixed value, then this value is called the (instantaneous) velocity v ( t ) {\textstyle v(t)} at the given time t {\displaystyle t} . If Δ t {\displaystyle \Delta t} denotes the position of the body at time 𝑡 , then write v ( t ) = x ′ ( t ) {\displaystyle v(t)=x'(t)} and call v {\displaystyle v} the derivative of x {\displaystyle x} .
The decisive step in the direction of differential equation models is now the reverse question: In the example of the moving body, let the velocity v ( t ) {\textstyle v(t)} be known at every point in time 𝑡 and its position x ( t ) {\displaystyle x(t)} be determined from this. It is clear that the initial position of the body at a point in time 𝑡 0 must also be known in order to be able to solve this problem unambiguously. We are therefore looking for a function x ( t ) {\displaystyle x(t)} with x ′ ( t ) = v ( t ) {\displaystyle x'(t)=v(t)} that fulfills the initial condition x ′ ( t ) = v ( t ) {\displaystyle x'(t)=v(t)} with given values t 0 {\displaystyle t_{0}} and x 0 {\displaystyle x_{0}} .
In the example of determining the position 𝑥 of a body from its velocity, the derivative of the function being searched for is explicitly given. In most cases, however, the important general case of ordinary differential equations exists for a sought-after variable y {\displaystyle y} : Due to the laws of nature or the model assumptions, a functional relation is known that specifies how the deriativey y ′ ( t ) {\displaystyle y'(t)} of the function to be determined can be calculated from t {\displaystyle t} and from the (unknown) value y ( t ) {\displaystyle y(t)} . In addition, an initial condition must again be given, which can be obtained, for example, from a measurement of the required variable at a fixed point in time. To summarize, the following general type of task exists: Find the function y {\displaystyle y} that satisfies the equations
is fulfilled, where f {\displaystyle f} is a given function.
A simple example is a variable y {\displaystyle y} that grows exponentially . This means that the instantaneous change, i.e. the derivative y ′ ( t ) {\displaystyle y'(t)} , is proportional to y ( t ) {\displaystyle y(t)} itself. Therefore, y ′ ( t ) = λ y ( t ) {\displaystyle y'(t)=\lambda y(t)} with a growth rate λ {\displaystyle \lambda } and, for example, an initial condition y ( 0 ) = y 0 {\displaystyle y(0)=y_{0}} . In this case, the required solution 𝑦 can already be found using elementary differential calculus and specified using the exponential function : y ( t ) = y 0 e λ t {\displaystyle y(t)=y_{0}e^{\lambda t}} .
The required function y {\displaystyle y} in a differential equation can be vector-valued, i.e. for each t {\displaystyle t} , y ( t ) = ( y 1 ( t ) , … , y d ( t ) ) {\displaystyle y(t)=(y_{1}(t),\dotsc ,y_{d}(t))} can be a vector with d {\displaystyle d} components. This is also referred to as an d {\displaystyle d} -dimensional system of differential equations. In the case of a moving body, y ( t ) {\displaystyle y(t)} is its position in d {\displaystyle d} -dimensional Euclidean space and y ′ ( t ) {\displaystyle y'(t)} is its velocity at time t {\displaystyle t} . The differential equation therefore specifies the velocity of the trajectory with direction and magnitude at each point in time and space. The trajectory itself is to be calculated from this.
In the simple differential equation of exponential growth considered above as an example, the solution function could be specified directly. This is generally no longer possible for more complicated problems. Under certain additional conditions, it is then possible to show that a clearly determined solution to the initial value problem exists for the function f {\displaystyle f} ; however, this can then no longer be explicitly calculated using solution methods of analysis (such as separation of variables , an exponential approach or variation of the constants). In this case, numerical methods can be used to determine approximations for the solution sought.
The methods for the numerical solution of initial value problems of ordinary differential equations can be roughly divided into two large groups: the one-step and the multi-step methods. Both groups have in common that they calculate approximations y 0 , y 1 , y 2 , … {\displaystyle y_{0},y_{1},y_{2},\dotsc } for the desired function values y ( t 0 ) , y ( t 1 ) , y ( t 2 ) , … {\displaystyle y(t_{0}),y(t_{1}),y(t_{2}),\dotsc } at points t 0 < t 1 < t 2 < … {\displaystyle t_{0}<t_{1}<t_{2}<\ldots } step by step. The defining characteristic of one-step methods is that only the "current" approximation y j + 1 {\displaystyle y_{j+1}} is used to determine the following approximation y j {\displaystyle y_{j}} . In contrast, multi-step methods also include previously calculated approximations; a three-step method would therefore use y j − 1 {\displaystyle y_{j-1}} and y j − 2 {\displaystyle y_{j-2}} to determine the new approximation y j + 1 {\displaystyle y_{j+1}} in addition to y j {\displaystyle y_{j}} .
The simplest and most basic one-step method is the explicit Euler method, which was introduced by the Swiss mathematician and physicist Leonhard Euler in 1768 in his textbook Institutiones Calculi Integralis. [ 2 ] The idea of this method is to approximate the solution sought by a piecewise linear function in which the gradient of the straight line piece is given by t j {\displaystyle t_{j}} in each step from the point math>t_{j+1}</math> to the point f ( t j , y j ) {\displaystyle f(t_{j},y_{j})} . In more detail: The problem definition already gives a value of the function being searched for, namely y ( t 0 ) = y 0 {\displaystyle y(t_{0})=y_{0}} . However, the derivative at this point is also known, as y ′ ( t 0 ) = f ( t 0 , y 0 ) {\displaystyle y'(t_{0})=f(t_{0},y_{0})} applies. This allows the tangent to the graph of the solution function to be determined and used as an approximation. At the point t 1 > t 0 {\displaystyle t_{1}>t_{0}} the following results with the step size h 0 := t 1 − t 0 {\displaystyle h_{0}:=t_{1}-t_{0}}
This procedure can now be continued in the following steps. Overall, this results in the following calculation rule for the explicit Euler method
with the increments h j = t j + 1 − t j {\displaystyle h_{j}=t_{j+1}-t_{j}} . [ 3 ]
The explicit Euler method is the starting point for numerous generalizations in which the gradient f ( t j , y j ) {\displaystyle f(t_{j},y_{j})} is replaced by gradients that approximate the behaviour of the solution between the points t j {\displaystyle t_{j}} and t j + 1 {\displaystyle t_{j+1}} more precisely. An additional idea for one-step methods is provided by the implicit Euler method, which uses f ( t j + 1 , y j + 1 ) {\displaystyle f(t_{j+1},y_{j+1})} as the gradient. At first glance, this choice does not seem very suitable, as y j + 1 {\displaystyle y_{j+1}} is unknown. However, as a procedural step, we now obtain the equation
from which y j + 1 {\displaystyle y_{j+1}} can be calculated (using a numerical method if necessary). If, for example, the arithmetic mean of the slopes of the explicit and implicit Euler method is selected as the slope, the implicit trapezoidal method is obtained. In turn, an explicit method can be obtained from this if, for example, the unknown y j + 1 {\displaystyle y_{j+1}} on the right-hand side of the equation is approximated using the explicit Euler method, the so-called Heun method. [ 4 ] All these methods and all other generalizations have the basic idea of one-step methods in common: the step
with a gradient Φ {\displaystyle \Phi } that can depend on t j {\displaystyle t_{j}} , y j {\displaystyle y_{j}} and h j {\displaystyle h_{j}} as well as (for implicit methods) on y j + 1 {\displaystyle y_{j+1}} .
With the considerations from the introductory section of this article, the concept of the one-step method can be defined as follows: Let the solution y {\displaystyle y} of the initial value problem be sought
It is assumed that the solution
exists on a given interval I = [ t 0 , T ] {\displaystyle I=[t_{0},T]} and is uniquely determined. Are
Intermediate positions in the interval I {\displaystyle I} and h j = t j + 1 − t j {\displaystyle h_{j}=t_{j+1}-t_{j}} the corresponding increments, then this is given by
given method is a one-step method with method function Φ {\displaystyle \Phi } . If Φ {\displaystyle \Phi } does not depend on y j + 1 {\displaystyle y_{j+1}} , then it is called an explicit one-step method. Otherwise, an equation for j {\displaystyle j} must be solved in each step j {\displaystyle j} and the method is called implicit. [ 5 ]
For a practical one-step procedure, the calculated y j {\displaystyle y_{j}} should be good approximations for the values y ( t j ) {\displaystyle y(t_{j})} of the exact solution y {\displaystyle y} at the point t j {\displaystyle t_{j}} . As the variables are generally d {\displaystyle d} -dimensional vectors, the quality of this approximation is measured using a vector norm as ‖ y j − y ( t j ) ‖ {\displaystyle \|y_{j}-y(t_{j})\|} , the error at the point t j {\displaystyle t_{j}} . It is desirable that these errors quickly converge to zero for all j {\displaystyle j} if the step sizes are allowed to converge to zero. In order to also capture the case of non-constant step sizes, h {\displaystyle h} is defined more precisely as the maximum of the step sizes used and the behavior of the maximum error at all points j {\displaystyle j} is considered in comparison to powers of h {\displaystyle h} . The one-step method for solving the given initial value problem is said to have the order of convergence p ≥ 1 {\displaystyle p\geq 1} if the estimate
applies to all sufficiently small h {\displaystyle h} with a constant C > 0 {\displaystyle C>0} that is independent of h {\displaystyle h} . [ 6 ] The order of convergence is the most important parameter for comparing different one-step methods. [ 7 ] A method with a higher order of convergence p {\displaystyle p} generally delivers a smaller total error for a given step size or, conversely, fewer steps are required to achieve a given accuracy. For a method with p = 1 {\displaystyle p=1} , it is to be expected that the error will only be approximately halved if the step size is halved. With a method of convergence order p = 4 {\displaystyle p=4} , on the other hand, it can be assumed that the error is reduced by a factor of approximately ( 1 2 ) 4 = 1 16 {\displaystyle {\bigl (}{\tfrac {1}{2}}{\bigr )}^{4}={\tfrac {1}{16}}} .
The errors ‖ y j − y ( t j ) ‖ {\displaystyle \|y_{j}-y(t_{j})\|} considered in the definition of the convergence order are made up of two individual components in a way that initially seems complicated: On the one hand, of course, they depend on the error that the method makes in a single step by approximating the unknown gradient of the function being searched for by the method function. On the other hand, however, it must also be taken into account that the starting point ( t j , y j ) {\displaystyle (t_{j},y_{j})} of a step generally does not match the exact starting point ( t j , y ( t j ) ) {\displaystyle (t_{j},y(t_{j}))} ; the error after this step therefore also depends on all errors that have already been made in the previous steps. Due to the uniform definition of the one-step procedures, which differ only in the choice of the procedure function Φ {\displaystyle \Phi } , it can be proven, however, that (under certain technical conditions at Φ {\displaystyle \Phi } ) one can directly infer the order of convergence from the error order in a single step, the so-called consistency order.
The concept of consistency is a general and central concept of modern numerical mathematics. While the convergence of a method involves investigating how well the numerical approximations match the exact solution, in simplified terms the "reverse" question is asked in the case of consistency: How well does the exact solution fulfill the method specification? In this general theory, a method is convergent if it is consistent and stable. To simplify the notation, the following consideration assumes that an explicit one-step procedure
with a constant step size h {\displaystyle h} exists. With the true solution t ↦ y ( t ) {\displaystyle t\mapsto y(t)} , the local truncation error (also called local process error) η {\displaystyle \eta } is defined as [ 8 ]
Thus, one assumes that the exact solution is known, starts a method step at the point ( t , y ( t ) ) {\displaystyle (t,y(t))} and forms the difference to the exact solution at the point t + h {\displaystyle t+h} . This defines: A one-step method has the consistency order p ≥ 1 {\displaystyle p\geq 1} if the estimate
applies to all sufficiently small h {\displaystyle h} with a constant C > 0 {\displaystyle C>0} that is independent of h {\displaystyle h} .
The striking difference between the definitions of the consistency order and the convergence order is the power h p + 1 {\displaystyle h^{p+1}} instead of h p {\displaystyle h^{p}} . This can be clearly interpreted as meaning that a power of the step size is "lost" during the transition from local to global error. The following theorem, which is central to the theory of one-step methods, applies: [ 9 ]
The Lipschitz continuity of the process function as an additional requirement for stability is generally always fulfilled if the function f {\displaystyle f} from the differential equation itself is Lipschitz-continuous. This requirement must be assumed for most applications anyway in order to guarantee the unambiguous solvability of the initial value problem. According to the theorem, it is therefore sufficient to determine the consistency order of a one-step method. In principle, this can be achieved by Taylor expansion of η ( t , h ) {\displaystyle \eta (t,h)} to powers of h {\displaystyle h} . In practice, the resulting formulas for higher orders become very complicated and confusing, so that additional concepts and notations are required. [ 10 ]
The convergence order of a method is an asymptotic statement that describes the behavior of the approximations when the step size converges to zero. However, it says nothing about whether the method actually calculates a useful approximation for a given fixed step size. Charles Francis Curtiss and Joseph O. Hirschfelder first described in 1952 that this can actually be a major problem for certain types of initial value problems. They had observed that the solutions to some differential equation systems in chemical reaction kinetics could not be calculated using explicit numerical methods and called such initial value problems "stiff". [ 11 ] There are numerous mathematical criteria for determining how stiff a given problem is. Stiff initial value problems are usually systems of differential equations in which some components become constant very quickly while other components change only slowly. Such behavior typically occurs in the modeling of chemical reactions. However, the most useful definition of stiffness for practical applications is: An initial value problem is stiff if, when solving it with explicit one-step methods, the step size would have to be chosen "too small" in order to obtain a useful solution. Such problems can therefore only be solved using implicit methods. [ 12 ]
This effect can be illustrated more precisely by examining how the individual methods cope with exponential decay . According to the Swedish mathematician Germund Dahlquist , the test equation
with the exponentially decreasing solution λ < 0 {\displaystyle \lambda <0} for y ( t ) = e λ t {\displaystyle y(t)=e^{\lambda t}} . The adjacent diagram shows - as an example for the explicit and implicit Euler method - the typical behavior of these two groups of methods for this seemingly simple initial value problem: If too large a step size is used in an explicit method, this results in strongly oscillating values that build up over the course of the calculation and move further and further away from the exact solution. Implicit methods, on the other hand, typically calculate the solution for arbitrary step sizes qualitatively correctly, namely as an exponentially decreasing sequence of approximate values. [ 13 ]
More generally, the above test equation is also considered for complex values of λ {\displaystyle \lambda } . In this case, the solutions are oscillations whose amplitude remains limited precisely when Re ( λ ) ≤ 0 {\displaystyle \operatorname {Re} (\lambda )\leq 0} , i.e. the real part of λ {\displaystyle \lambda } is less than or equal to 0. This makes it possible to formulate a desirable property of one-step methods that are to be used for stiff initial value problems: the so-called A-stability. A method is called A-stable if it calculates a sequence of approximations h > 0 {\displaystyle h>0} for any step size y 0 , y 1 , y 2 , … {\displaystyle y_{0},y_{1},y_{2},\dotsc } applied to the test equation for all λ {\displaystyle \lambda } with Re ( λ ) ≤ 0 {\displaystyle \operatorname {Re} (\lambda )\leq 0} , which remains bounded (like the true solution). The implicit Euler method and the implicit trapezoidal method are the simplest examples of A-stable one-step methods. On the other hand, it can be shown that an explicit method can never be A-stable. [ 14 ]
As the French mathematician Augustin-Louis Cauchy proved around 1820, the Euler method has a convergence order of 1. If you average the slopes f ( t j , y j ) {\displaystyle f(t_{j},y_{j})} of the explicit Euler method and f ( t j + 1 , y j + 1 ) {\displaystyle f(t_{j+1},y_{j+1})} of the implicit Euler method, as they exist at the two end points of a step, [ 15 ] you can hope to obtain a better approximation over the entire interval. In fact, it can be proven that the implicit trapezoidal method obtained in this way
has a convergence order of 2. This method has very good stability properties, but is implicit, meaning that an equation for 𝑦 𝑗 + 1 must be solved in each step. If this variable is approximated on the right-hand side of the equation using the explicit Euler method, the result is the explicit method of Heun [ 16 ]
which also has convergence order 2. Another simple explicit method of order 2, the improved Euler method, is obtained by the following consideration: A "mean" slope in the method step would be the slope of the solution 𝑦 in the middle of the step, i.e. at the point y j + 1 {\displaystyle y_{j+1}} . However, as the solution is unknown, it is approximated by an explicit Euler step with half the step size. This results in the following procedure
These one-step methods of order 2 were all published as improvements of the Euler method in 1895 by the German mathematician Carl Runge. [ 17 ]
The aforementioned ideas for simple one-step methods lead to the important class of Runge-Kutta methods when generalized further. For example, Heun's method can be presented more clearly as follows: First, an auxiliary slope k 1 = f ( t j , y j ) {\displaystyle k_{1}=f(t_{j},y_{j})} is calculated, namely the slope of the explicit Euler method. This is used to determine a further auxiliary slope, here k 2 = f ( t j + h , y j + h k 1 ) {\displaystyle k_{2}=f(t_{j}+h,y_{j}+hk_{1})} . The actual process gradient Φ {\displaystyle \Phi } used is then calculated as a weighted average of the auxiliary gradients, i.e. 1 2 k 1 + 1 2 k 2 {\displaystyle {\tfrac {1}{2}}k_{1}+{\tfrac {1}{2}}k_{2}} in Heun's method. This procedure can be generalized to more than two auxiliary slopes. An s {\displaystyle s} - -stage Runge-Kutta method first calculates auxiliary slopes k 1 , … , k s {\displaystyle k_{1},\dotsc ,k_{s}} by evaluating 𝑓 at suitable points and then Φ {\displaystyle \Phi } as a weighted average. In an explicit Runge-Kutta method, the auxiliary slopes k 1 , k 2 , k 3 , … {\displaystyle k_{1},k_{2},k_{3},\dotsc } are calculated directly one after the other; in an implicit method, they are obtained as solutions to a system of equations. A typical example is the explicit classical Runge-Kutta method of order 4, which is sometimes simply referred to as the Runge-Kutta method: First, the four auxiliary slopes [ 18 ]
and then the weighted average is calculated as the process slope
is used. This well-known method was published by the German mathematician Wilhelm Kutta in 1901, after Karl Heun had found a three-step one-step method of order 3 a year earlier. [ 19 ]
The construction of explicit methods of even higher order with the smallest possible number of steps is a mathematically quite demanding problem. As John C. Butcher was able to show in 1965, there are, for example, only a minimum of six steps for order 5; an explicit Runge-Kutta method of order 8 requires at least 11 steps. In 1978, the Austrian mathematician Ernst Hairer found a method of order 10 with 17 levels. The coefficients for such a method must fulfill 1205 determinant equations. With implicit Runge-Kutta methods, [ 20 ] the situation is simpler and clearer: for every number of steps s {\displaystyle s} there is a method of order p = 2 s {\displaystyle p=2s} ; this is also the maximum achievable order. [ 21 ]
The idea of extrapolation is not limited to the solution of initial value problems with one-step methods, but can be applied analogously to all numerical methods that discretize the problem to be solved with a step size h {\displaystyle h} . A well-known example of an extrapolation method is the Romberg integration for the numerical calculation of integrals. In general, let v {\displaystyle v} be a value that is to be determined numerically, in the case of this article, for example, the value of the solution function of an initial value problem at a given point. A numerical method, for example a one-step method, calculates an approximate value v ~ ( h ) {\displaystyle {\tilde {v}}(h)} for this, which depends on the choice of step size h > 0 {\displaystyle h>0} . It is assumed that the method is convergent, i.e. that v ~ ( h ) {\displaystyle {\tilde {v}}(h)} converges to v {\displaystyle v} when h {\displaystyle h} converges to zero. However, this convergence is only a purely theoretical statement, as approximate values v ~ ( h 1 ) , v ~ ( h 2 ) , … , v ~ ( h m ) {\displaystyle {\tilde {v}}(h_{1}),{\tilde {v}}(h_{2}),\dotsc ,{\tilde {v}}(h_{m})} can be calculated for a finite number of different step sizes h 1 > h 2 > … > h m {\displaystyle h_{1}>h_{2}>\ldots >h_{m}} , but of course the step size cannot be allowed to "converge to zero". However, the calculated approximations for different step sizes can be interpreted as information about the (unknown) function v ~ {\displaystyle {\tilde {v}}} : In the extrapolation methods, v ~ {\displaystyle {\tilde {v}}} is approximated by an interpolation polynomial, i.e. by a polynomial P {\displaystyle P} with [ 22 ]
for k = 1 , 2 , … , m {\displaystyle k=1,2,\dotsc ,m} . The value P ( 0 ) {\displaystyle P(0)} of the polynomial at the point h = 0 {\displaystyle h=0} is then used as a computable approximation for the non-computable limit value of v ~ ( h ) {\displaystyle {\tilde {v}}(h)} for h {\displaystyle h} towards zero. An early successful extrapolation algorithm for initial value problems was published by Roland Bulirsch and Josef Stoer in 1966. [ 23 ]
A concrete example in the case of a one-step method of order p {\displaystyle p} can illustrate the general procedure of extrapolation. With such a method, the calculated approximation for small step sizes ℎ can be easily described by a polynomial of the form
with initially unknown parameters a {\displaystyle a} and b {\displaystyle b} . If you now calculate two approximations y h 1 {\displaystyle y_{h_{1}}} and y h 2 {\displaystyle y_{h_{2}}} using the method for a step size h 1 {\displaystyle h_{1}} and for half the step size h 2 = 1 2 h 1 {\displaystyle h_{2}={\tfrac {1}{2}}h_{1}} , two linear equations for the unknowns a {\displaystyle a} and b {\displaystyle b} are obtained from the interpolation conditions P ( h 1 ) = y h 1 {\displaystyle P(h_{1})=y_{h_{1}}} and P ( h 2 ) = y h 2 {\displaystyle P(h_{2})=y_{h_{2}}} .
is then generally a significantly better approximation than the two values calculated initially. It can be shown that the order of the one-step method obtained in this way is at least p + 1 {\displaystyle p+1} , i.e. at least 1 greater than the original method. [ 24 ]
One advantage of the one-step method is that any step size j {\displaystyle j} can be used in each step 𝑗 independently of the other steps. In practice, this obviously raises the question of how ℎ 𝑗 should be selected. In real applications, there will always be an error tolerance with which the solution of an initial value problem is to be calculated; for example, it would be pointless to determine a numerical approximation that is significantly more "accurate" than the data for initial values and parameters of the given problem, which are subject to measurement errors . The aim will therefore be to select the step sizes in such a way that, on the one hand, the specified error tolerances are adhered to and, on the other hand, as few steps as possible are used in order to keep the computational effort to a minimum. This problem, in which an ordinary differential equation is given together with an initial condition, plays a central role in all natural and engineering sciences and is also becoming increasingly important in the economic and social sciences, for example. Initial value problems are used to analyze, simulate or predict dynamic processes. [ 25 ]
For well- conditioned initial value problems, it can be shown that the global process error is approximately equal to the sum of the local truncation errors η j := ‖ η ( t j , h j ) ‖ {\displaystyle \eta _{j}:=\|\eta (t_{j},h_{j})\|} in the individual steps. Therefore, the largest possible h j {\displaystyle h_{j}} should be selected as the step size, for which η j {\displaystyle \eta _{j}} is below a selected tolerance threshold. The problem here is that η j {\displaystyle \eta _{j}} cannot be calculated directly, as it depends on the unknown exact solution y ( t j ) {\displaystyle y(t_{j})} of the initial value problem at the point t j {\displaystyle t_{j}} . The basic idea of step size control is therefore to approximate y ( t j ) {\displaystyle y(t_{j})} with a method that is more accurate than the underlying basic method. [ 26 ]
Two basic ideas for step width control are step width halving and embedded processes. With step size halving, the result for two steps with half the step size is calculated as a comparison value in addition to the actual process step. A more precise approximation for y ( t j ) {\displaystyle y(t_{j})} is then determined from both values by extrapolation and the local error 𝜂 𝑗 is estimated. If this is too large, this step is discarded and repeated with a smaller step size. If it is significantly smaller than the specified tolerance, the step size can be increased in the next step. [ 27 ] The additional computational effort for this step width halving procedure is relatively high; this is why modern implementations usually use so-called embedded procedures for step width control. The basic idea is to calculate two approximations for y ( t j ) {\displaystyle y(t_{j})} in each step using two one-step methods that have different orders of convergence and thus estimate the local error. In order to optimize the computational effort, the two methods should have as many computational steps in common as possible: They should be "embedded in each other". Embedded Runge-Kutta methods, for example, use the same auxiliary slopes and differ only in how they average them. Well-known embedded methods include the Runge-Kutta-Fehlberg method ( Erwin Fehlberg [ de ] , 1969) and the Dormand-Prince method (J. R. Dormand and P. J. Prince, 1980). [ 28 ]
Numerous software implementations have been developed for the mathematical concepts outlined in this article, which allow the user to solve practical problems numerically in a simple way. As a concrete example, a solution to the Lotka-Volterra equations will now be calculated using the popular numerical software Matlab. The Lotka-Volterra equations are a simple model from biology that describes the interactions between predator and prey populations . Given the differential equation system
with the parameters a = 1 , b = 2 , c = 1 , d = 1 {\displaystyle a=1,b=2,c=1,d=1} and the initial condition y 1 ( 0 ) = 3 {\displaystyle y_{1}(0)=3} , y 2 ( 0 ) = 1 {\displaystyle y_{2}(0)=1} . Here, y 1 {\displaystyle y_{1}} and y 2 {\displaystyle y_{2}} correspond to the temporal development of the prey and predator population respectively. The solution should be calculated on the time interval [ 0 , 20 ] {\displaystyle [0,20]} .
For the calculation using Matlab, the function f {\displaystyle f} is first defined for the given parameter values on the right-hand side of the differential equation y ′ = f ( t , y ) {\displaystyle y'=f(t,y)} :
The time interval and the initial values are also required:
The solution can then be calculated:
The Matlab function ode45 implements a one-step method that uses two embedded explicit Runge-Kutta methods with convergence orders 4 and 5 for step size control. [ 29 ]
The solution can now be plotted, y 1 {\displaystyle y_{1}} as a blue curve and y 2 {\displaystyle y_{2}} as a red curve; the calculated points are marked by small circles:
The result is shown below in the left-hand image. The right-hand image shows the step sizes used by the method and was generated with
This example can also be executed without changes using the free numerical software GNU Octave. However, the method implemented there results in a slightly different step size sequence. | https://en.wikipedia.org/wiki/One-step_method |
OneSubsea is a SLB company, headquartered in Oslo, Norway and Houston, Texas , United States. [ 4 ] The company is a subsea supplier [ 5 ] for the subsea oil and gas market.
As of August 2024, the company is the worlds largest in terms of installed subsea christmas trees [ 6 ]
In November 2012, Cameron International and Schlumberger announced that they were forming a Joint venture called OneSubsea. Cameron would manage OneSubsea with a 60% interest, with Schlumberger retaining 40%. [ 7 ] [ 8 ]
In January 2015, Helix, OneSubsea and Schlumberger formed the Subsea Services Alliance to develop technologies and deliver equipment and services to optimize the value chain of subsea well intervention systems. [ 9 ]
In July 2015, Subsea 7 and OneSubsea entered into an agreement to form a non-incorporated alliance. The alliance was formed to focus on subsea production systems (SPS) and subsea processing systems, subsea umbilicals, risers and flowlines systems (SURF), and life-of-field services. [ 10 ] [ 11 ]
In August 2015, OneSubsea was awarded a contract to supply subsea processing systems for Shell 's Stones development in the Gulf of Mexico . [ 12 ]
Schlumberger announced in August 2015 that it was acquiring Cameron and OneSubsea for $14.8 billion. [ 13 ]
Schlumberger announced in August 2022, that OneSubsea was going into a joint venture with AkerSolutions and Subsea7. The ownership of OneSubsea is 70% with Schlumberger, 20% with AkerSolutions and Subsea7 owning the last 10% [ 14 ] [ better source needed ]
In July 2024, it was announced that OneSubsea was awarded the contract to front-end design an all electric subsea tree project from Equinor called Fram-Sør. [ 15 ] [ better source needed ] | https://en.wikipedia.org/wiki/OneSubsea |
The OneZoom Tree of Life Explorer is a web-based phylogenetic tree software. It aims to map the evolutionary connection of all known life . As of 2023 it includes over 2.2 million species . [ 1 ] [ 2 ]
OneZoom was originally invented by James Rosindell [ 3 ] and is a charity registered in London . [ 4 ] It is sponsored by individuals such as Richard Dawkins . [ 3 ] [ 5 ]
The design is based on the pythagoras tree ; beside a default spiral design there are other options, such as polytomy . [ 6 ] [ 7 ]
Leaves and nodes provide links to other websites, such as Wikipedia , Encyclopedia of Life or the NCBI taxonomy browser. The leaves representing single species are colour-coded according to their IUCN extinction risk, with red indicating a threatened species, black representing a recently extinct species, and grey representing species with unknown extinction risk. [ 1 ] | https://en.wikipedia.org/wiki/OneZoom |
One New Zealand (formerly known as Vodafone New Zealand ) is a New Zealand telecommunications company. [ 2 ] [ 3 ] One NZ is the largest wireless carrier in New Zealand , accounting for 38% of the country's mobile share market in 2021. [ 4 ]
One NZ is based in Auckland and was formed in 1998 as Vodafone New Zealand, after Vodafone purchased BellSouth 's New Zealand operations. The company employs over 3,000 people and has operations nationwide, with its main offices based in Auckland, Wellington and Christchurch. The company is part of the New Zealand Telecommunications Forum .
In October 2006, Vodafone bought ihug , New Zealand's third largest Internet service provider at the time, to provide internet services under the Vodafone name. [ 5 ]
In 2012 Vodafone bought TelstraClear , making it New Zealand's second largest internet service provider. [ 6 ]
In June 2016, Sky TV and Vodafone agreed to merge, with Sky TV purchasing 100% of Vodafone NZ operations for a cash payment of NZ$1.25 billion and issuing new shares to the Vodafone Group. Vodafone UK was to get 51% stake of the company. [ 7 ] However, the proposed merger was rejected by the Commerce Commission , resulting in a plunge in Sky TV's shares, and the proposed merger was not completed. [ 8 ]
The company has invested hundreds of millions of dollars in its mobile network, improving capacity in congested urban areas. It launched New Zealand's first 4G LTE network and continues to maintain its 2G network. In February 2013, Vodafone New Zealand launched New Zealand's first LTE mobile network which is currently available to 98% of the population. [ 9 ] In June 2014, Vodafone New Zealand was ranked the fastest mobile network on the planet by speed-testing service Ookla . [ 10 ] In December 2019, Vodafone New Zealand launched New Zealand's first 5G mobile network which is currently available in more than 70 towns and cities across New Zealand. [ 9 ]
It ceased to be a subsidiary of the London-listed company Vodafone Plc on 31 July 2019, when its sale to a consortium comprising Infratil Limited and Brookfield Asset Management Inc. was settled. [ 11 ] The sold company would continue to use the Vodafone brand under a commercial arrangement with Vodafone plc. [ 12 ]
In March 2022, Vodafone New Zealand was awarded the best mobile network in New Zealand by umlaut. [ 13 ] In August 2022, Vodafone New Zealand announced that from 31 August 2024, Vodafone New Zealand will start to switch off their 3G mobile network to allow further expansion of One NZ's 4G / 5G mobile network, Vodafone New Zealand have assured customers that 3G coverage areas will be upgraded to new technologies such as 4G . [ 14 ]
On 28 September 2022, it was announced that Vodafone New Zealand would change its name to One New Zealand in early 2023. [ 15 ] [ 16 ] [ 17 ]
Stuff News reported that the naming change could save the company between $20 million and $30 million that it would otherwise be paying in licensing fees. [ 18 ] Vodafone NZ states that customers' ability to roam on networks overseas will be unaffected by the name change.
Stuff published an article titled "Could Vodafone's rebrand to One New Zealand backfire?", stating that the naming change could be tarnished by the name's association with the defunct NZ political party One NZ. [ 19 ] In response, the company's CEO Jason Paris said on Twitter "One NZ stands for the best of NZ (diversity, inclusion, trust, innovation etc)". [ 20 ]
Vodafone NZ's website started to redirect users to the one.nz website on 28 March 2023.
One NZ currently operates New Zealand's largest 5G mobile network and New Zealand's only 2G mobile network. [ 9 ] On 3 April 2023, Vodafone NZ had officially announced their change to One NZ, while also announcing a deal with SpaceX to provide 100% mobile coverage through their Starlink satellite internet service, which was announced to be released in late 2024. [ 2 ] [ 3 ]
In May 2023, One NZ was awarded the best mobile network in New Zealand by Umlaut. [ 21 ]
On 7 June 2023, Infratil announced that they would be taking full control of One NZ by buying out all shares from Brookfield Asset Management. This brought the Infratil ownership to 99.90%, making One NZ a New Zealand owned company. [ 22 ] A small percentage of the company is owned by executives. [ 23 ]
In August 2023, One NZ was fined over $3 million for breaching the Fair Trading Act by misleading consumers about their FibreX service. One NZ incorrectly told people that FibreX was the only broadband service available at their location. [ 24 ]
In May 2024, One NZ was awarded the best mobile network in New Zealand by Umlaut. [ 25 ] [ 26 ]
In October 2024, One NZ received approval to test Starlink Satellite to mobile SMS service. This came as the FCC voted unanimously in favor of its Supplemental Coverage from Space (SCS) regulatory framework on 14 March 2024. [ 27 ]
One NZ has 2.4 million customers. [ 28 ] According to the Commerce Commission's Annual Telecommunications Monitoring Report from March 2022, One NZ's market share in the mobile market was 38%, Spark 41% and Two Degrees Mobile 19%. The remainder of 2% the market is made up of mobile virtual network operators . [ 29 ]
BellSouth had 138,000 customers when it was purchased by Vodafone in November 1998. BellSouth's main rival was Telecom New Zealand (now Spark), New Zealand's second largest telecommunications company behind Vodafone. Telecom had the advantage that it had a 6-year head-start on BellSouth, however this advantage slipped away in recent years. After Vodafone took over Bellsouth, it expanded network coverage to compete more effectively with Telecom. Vodafone has constantly increased its market share and surpassed Telecom in mobile customers. [ citation needed ]
On 11 October 2006, Vodafone acquired ihug from iiNet , and closed the ihug brand in 2008. ihug was a popular Internet Service Provider and was notable for introducing a flat rate account in 1995.
On 31 October 2012, Vodafone acquired 100% of TelstraClear from Australian company Telstra . TelstraClear had its beginnings in New Zealand with Kiwi Cable, Clear Communications in 1990, and Telstra New Zealand in 1996.
Telstra NZ expanded its operations in the business market, bundling Telecom New Zealand services distributed as a reseller with its own network services. It maintained interconnect agreements with Telecom New Zealand, Clear Communications and some smaller service providers. In 1999 Saturn Communications was sold by its parent company, Austar United Communications, to a new joint venture with Telstra that became known as TelstraSaturn . TelstraClear was then created by the merger of Telstra's TelstraSaturn and Clear Communications in December 2001.
In July 2012 Vodafone NZ approached Telstra to purchase TelstraClear for a payment of $840 million, and $450 million that TelstraClear had in its accounts. The Commerce Commission approved the bid on 30 October, and the sale was completed on 31 October. [ 30 ] TelstraClear's final trading day was 31 March 2013. [ citation needed ]
On 10 June 2015, Vodafone NZ acquired WorldxChange, a New Zealand based telecommunications business. [ 31 ] [ 32 ] WorldxChange delivered communications services to Government, Corporate, and business customers; and fibre broadband to residential customers.
In February 2022 Vodafone NZ signed a conditional agreement to acquire a 60% majority share in cyber security specialist company Defend. [ 33 ]
One NZ committed to acquiring Dense Air, in order to use their 2x35MHz of 2600 MHz spectrum rights, and immediately deploy it for use on its 5G network. The acquisition of Dense Air by One NZ was approved by the Commerce Commission on 6 May 2024. [ 34 ] [ 35 ]
One NZ operates a GSM (2G) mobile phone network at 900 MHz, a UMTS (3G) network at 900 MHz and 2100 MHz, a 4G LTE network at 700 MHz, 900 MHz 1800 MHz, 2100 MHz and 2600 MHz and a 5G NR network. It states that the network provides service in "Our mobile network covers over 99% of the population, with 4G/5G coverage to over 99% by late 2024". [ 36 ]
On 25 October 2024, One NZ confirmed that it would delay plans to close its 2G and 3G services until 31 December 2025. [ 37 ] [ 38 ]
One NZ operates a nationwide GSM service in the 900 MHz band. In areas with high demand One used to operate additional GSM services in the 1800 MHz band, usually from existing 900 MHz cell sites, to provide more capacity. Areas that had both 900 MHz and 1800 MHz service included most major business districts and large shopping malls. In later years One NZ also established some cell sites that only provided 1800 MHz service where it was difficult to release spectrum for more 900 MHz cell sites. Most phones sold since the mid-1990s supported both bands.
In March 2016 Vodafone New Zealand announced plans to shut down its 2G (GSM) network, beginning with voice and messaging services. Vodafone's Spokesperson Elissa Downey commented that they would keep the GSM network running until 2025, although it would only support devices using GSM data such as electricity meters that send readings over the network, and that they would be announcing the end date for its 2G voice service soon. [ 39 ] In early August 2016, however, it was reported that Vodafone was reconsidering its choice to shut down the network, with Spokesperson Andrea Brady stating that the 2G network "will not be switched off anytime soon as it continues to serve customers across New Zealand". [ 40 ] This announcement came following the company's criticism of rival operator Spark 's billboard campaign that claimed "Vodafone's 2G network is shutting down" and invited customers to "switch before [they're] ditched", [ 41 ] despite neither Spark, nor its child division Skinny Mobile – whom the campaign was run under – operating a compatible 2G network. The campaign was denounced by Vodafone as "pretty misleading", shortly followed by the announcement that 2G voice services would not be ended any time soon. [ 42 ] As of December 2023 One NZ has not confirmed a date for the termination of its 2G voice network.
In the main centres, One NZ operates UMTS (3G) service using the 2100 MHz band. UMTS service is often provided from the same cell site as 900 MHz and/or 1800 MHz GSM services. Most of the existing 900 MHz sites were built in the 1990s when it was not expected that a 2100 MHz network would be built, hence the existing 900 MHz network was not at all optimised for 2100 MHz service. Due to the fact that 900 MHz and 1800 MHz signals propagate further than 2100 MHz signals, there were many areas beyond 2100 MHz coverage where UMTS phones would have to hand down to 900 MHz or 1800 MHz GSM service. One NZ established many individual 2100 MHz UMTS sites to enhance 3G coverage.
In rural areas, One NZ has installed 900 MHz UMTS (3G) service alongside their existing 900 MHz GSM (2G) service. The 900 MHz UMTS service has roughly the same coverage area as 900 MHz GSM service, so instances of UMTS service being handed down to GSM should occur far less often in rural areas than in areas covered by the 2100 MHz network. However, older UMTS phones only support 2100 MHz service so these phones will hand down to 900 MHz GSM even though there is UMTS service available at 900 MHz.
Rural Broadband Initiative ( RBI ) coverage: One NZ have a contract with the New Zealand government to provide fixed cellular access to the internet with antennas mounted on the outside of buildings, homes and businesses at speeds of at least 5 Mbit/s. Much of the coverage as of 2015 is on 900 MHz 3G (hands down to 2G as a backup). By January 2016, One NZ had actively extended its 4G network throughout key rural areas, and was on track to deliver speeds as high as 100 Mbit/s. [ 43 ]
RBI services is sold by many ISPs and can include voice services and internet services designed to give similar plans and pricing as landline. One NZ wholesales RBI services over cellular to many ISPs, and any ISP may provide RBI services over cellular, ADSL and UFB fibre, whatever is available at the customer's rural property (urban areas are excluded from RBI offerings).
One NZ offers 4G LTE coverage across New Zealand, claiming coverage to over 99% of the population by late 2024. One NZ uses frequencies at 700 MHz (Band 28), 900 MHz (Band 8), 1800 MHz (Band 3), 2100 MHz (Band 1), and 2600 MHz (Band 7) for 4G.
4G was originally considered an "add-on" and was included in three higher level plans [ 44 ] and the Vodafone Red plans. [ 45 ] The 700 MHz 4G LTE frequency used in New Zealand is APT band 28 and was first launched by Vodafone in Papakura on 21 July 2014. [ 46 ] [ 47 ]
One NZ launched its 5G service in Auckland , Wellington , Christchurch and Queenstown on 10 December 2019, and rolled out the service to other cities in recent years. One NZ plans to roll out 4G/5G to 99% of the population by late 2024 as the One NZ 3G network will no longer be available in these areas. [ 9 ]
One NZ also provides services for mobile virtual network operators . This means other companies can resell One NZ's network services (data, telephone and SMS) under their own brand name. Their customers connect to One NZ's network as any other One NZ customer would, but instead of seeing "One NZ" as the network operator, they will see the name of the company they pay for these services.
MVNO networks do not have their own cellular equipment, so customers connect to One NZ's network constantly, instead of jumping between networks. Current MVNOs running on One NZ's network include: Kogan Mobile , Mighty Mobile (owned by online retailer Mighty Ape ) [ 48 ] and formerly Black + White Mobile . [ 49 ]
This differed from a roaming arrangement previously in place with 2degrees, who offloaded customers onto the (former) Vodafone network when they were not in a 2degrees mobile coverage zone. 2degrees had this roaming agreement with Vodafone until 2020, and as such, their customers roamed only on the network when they had no coverage, otherwise they would connect to 2degrees' own equipment.
In New Zealand, all mobile phone numbers start with 02. One NZ is allocated the 021 prefix with other networks being allocated other prefixes – such as 022 to 2degrees, and 027 to Spark. However Number portability was introduced to the New Zealand market on 2 April 2007 which means that customers can bring, for example, their 021 prefixed number to Spark or 2degrees.
Vodafone NZ used to operate the 029 prefix on behalf of TelstraClear , in addition to its own 021 prefix. TelstraClear customers, mostly corporates, were able to get mobile numbers with this prefix; these customers were billed by TelstraClear, rather than being billed directly by Vodafone. This agreement lapsed in 2007, and in 2008 some of these customers were transitioned to Telecom who serviced them initially with CDMA2000 technology. Those TelstraClear 029 customers not transitioned to Telecom New Zealand remained with Vodafone. Subsequently, TelstraClear joined Telecom as a MVNO operator, but that relationship soured and TelstraClear re-signed with Vodafone in 2009, "ending the possibility of a move to Telecom's new XT network" [ 50 ] and remaining on the Vodafone network.
Spark NZ (formerly Telecom New Zealand), One NZ's rival, has fixed 10-digit numbers under its 0272-0279 prefix, which allows approximately 7 million possible numbers. Telecom originally had mixed 9-digits and 10-digits number using the older 025 prefix. The 027 prefix with only 10-digit numbers simplified its numbering system at the time of launching its CDMA network. The older 025 prefix was phased out with its now redundant AMPS and TDMA networks.
On Wednesday 10 August 2005 Vodafone introduced a new 3G network employing the UMTS technology widely used in Europe and elsewhere. Using this standard, Vodafone now offers Video Calling , music downloads, SKY mobile TV and other services from its Vodafone live! portal.
Vodafone began rolling out HSPA+ data services on its UMTS network in 2011; at the time of writing (May 2012), Auckland, Wellington and Christchurch have coverage. HSPA+ is capable of a theoretical maximum 168 Mbit/s download speed and 22 Mbit/s upload speed, although higher speeds are only supported in areas with an excellent radio signal.
Vodafone launched HD Voice [ 51 ] on 7 November 2013 – a high definition voice call technology. This technology works over 3G with HD Voice compatible phones on Vodafone to Vodafone voice calls.
One NZ has announced the dates for its 3G closure, which will be shut down on 31 March 2025. [ 52 ] [ 53 ]
The first iPhone 3G released on 11 July 2008 was sold by Vodafone in Auckland, New Zealand to 22-year-old student Jonny Gladwell at 12:01 am NZST . [ 54 ] The iPhone 3G was only available to customers on the Vodafone network. [ 55 ] 3G coverage for iPhone 3G was limited to major urban centres, as the phone operated on 850, 1900 and 2100 MHz bands; Vodafone's 3G network uses 900 and 2100 MHz. (The 850 MHz 3G band is used by Spark NZ.) 900 MHz capability was added from the iPhone 3GS and subsequent models of iPhone.
Subsequent launches of iPhone models in New Zealand have typically been a few weeks after the worldwide release. The iPhone 5 , iPhone 5s and iPhone 5c are CAT3 4G devices and can be used on One NZ's 4G LTE network on the 1800 MHz frequency. iPhone 6 and iPhone 6 Plus models are CAT4 4G devices and also support the APT 700 MHz frequency (Band 28) in addition to Vodafone's 1800 MHz frequency.
One NZ still offers copper-based ADSL and VDSL services. [ 56 ] (Vodafone had inherited two more ISPs, Paradise.net and Clearnet when it purchased TelstraClear.)
One NZ also offers DOCSIS cable modem broadband within the former TelstraClear's network. [ 57 ]
In June 2016, Vodafone upgraded its cable network to DOCSIS 3.1, in order to support gigabit speeds. [ 58 ]
One NZ currently offers a single option on the cable network. The standard plan provides up to 912 Mbit/s download and 104 Mbit/s upload. [ 59 ]
One NZ's cable network is available in the following areas:
One NZ offers a range of Ultra-Fast Broadband (UFB fibre) products.
One NZ, then Vodafone operated an internet television (IPTV) service under the brand "VodafoneTV". It was delivered over a broadband connection. The TV service was originally operated over a cable network formerly owned by TelstraClear in Auckland, Wellington, and Christchurch.
Customers could receive Freeview channels via a Vodafone TV box and had the ability to subscribe to Sky TV channels. Selected content was available in high-definition.
TechTV was available up until May 2004, when current owner Comcast halted international broadcasts. Chilli, an adult channel was also available until 2006 when CEO Alan Freeth discontinued the product on moral grounds. [ 60 ] Visitor TV was closed down after the 22 February earthquake .
In September 2010, TelstraClear released their own PVR called the T-Box. The launch followed the release by parent company Telstra (AU) of a similar product. As of June 2011, TelstraClear ceased all analogue transmission on its cable network.
VodafoneTV was relaunched in 2019 as a standalone product. A customer could purchase a VodafoneTV box from a retailer and access the service using any broadband provider. The new box had various OTT media streaming apps pre-installed.
Vodafone announced the closure of the VodafoneTV service on 9 December 2021, [ 61 ] to be retired on 30 September 2022. This end date was then extended to 28 February 2023, before finally closing on 31 March 2023.
In May 2024, One NZ's advertising started with the slogan "Let's get connected". [ 62 ]
Between 2006 and 2009, Vodafone ran a series of advertisements and promotions which were found to be misleading, and led to complaints—and eventually a series of large fines in 2011 and 2012 [ 63 ] [ 64 ] after action was taken by the Commerce Commission under the Fair Trading Act . Vodafone NZ issued an apology for this incident. [ 65 ] | https://en.wikipedia.org/wiki/One_NZ |
One Through Zero (The Ten Numbers) is a monumental series of sculptures by the American artist Robert Indiana . The work depicts the numerical digits 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , and 9 and 0 . The work was created between 1980 and 2001. [ 1 ] The numbers are made from polychrome aluminium with each measuring 72 x 72 x 36 in. (182.9 x 182.9 x 91.4 cm.). [ 1 ]
The use of numbers became prominent in Indiana's artworks from the end of the 1950s and became an established part of his style in the 1960s. The design of the numbers was inspired by a printer's calendar Indiana found in his loft in Coenties Slip . The piece was first created for a property developer in Indianapolis; the work was then donated to the Indianapolis Museum of Art . The work was subsequently created for a siting in Park Avenue in New York City in 2003 as part of the 'Art on the Park' series, [ 1 ] outside Beverly Hills City Hall in 2005, [ 2 ] and on Lime Street, London from 2013 as part of the City of London 's 'Sculpture in the City' series. [ 1 ] An edition of One Through Zero (The Ten Numbers) made from COR-TEN steel was displayed in London's Regent's Park in 2019. [ 3 ]
Indiana had previously created a work with the poet Robert Creeley of a book of poems with poems about each number facing Indiana's screen printed coloured numbers. [ 4 ]
The digits can be arranged in any order to generate new meanings and interpretations. [ 1 ]
Indiana ascribed particular meanings to the colours that he chose for each digit. [ 1 ]
Indiana's website ascribes the meanings as: | https://en.wikipedia.org/wiki/One_Through_Zero_(The_Ten_Numbers) |
One Water is a term encompassing the management of all water sources in an integrated and sustainable way considering all water sources and uses. [ 1 ] This idea stems from core principles of providing affordable water access for everyone. [ 2 ]
The term “One Water” refers to integrated and effective water management practices that are “older than Texas.” [ 3 ] Holistic, system-wide, interconnected approaches to water have been used before.
Holistic water planning by municipalities has become an international trend. [ 4 ] The international water community developed Integrated Water Resources Management (IWRM) in the early 2000s to protect water resources and promote sustainability. The Global Water Partnership has an IWRM Action hub to share information and insights into implementing an integrated water program. [ 5 ]
The Water Research Foundation (WRF) defines One Water as an integrated planning and implementation approach to managing finite water resources for long-term resilience and reliability, meeting both community and ecosystem needs. [ 1 ] While many cities manage various water sources and disposal systems separately, One Water emphasizes integrating water and land resources for a holistic planning approach to water management. [ 6 ] The importance of all water sources is stressed. [ 7 ] One Water principles involve taking an interconnected approach to complex issues such as water infrastructure crises, environmental and public health crises, droughts, and climate change at a all scales: individual and building, local, regional, state, country, and international. [ 8 ]
Jiang et al. 2021 developed a model using One Water concepts to show how thinking about interconnections can improve modeling and assessing the hydrologic cycle. [ 9 ]
The United Nations and World Health Organization host the WHO/UNICEF Joint Monitoring Programme (JMP) for Water Supply, Sanitation and Hygiene Program that uses One Water principles to monitor progress on local to global scales for attaining Sustainable Development Goal targets for “universal and equitable access to safe drinking water , sanitation , and hygiene.” [ 10 ]
The Environmental Protection Agency noted that meeting the Clean Water Act (1972 requirements for managing and accessing water would be more efficient using an overall approach to water management. [ 6 ] The agency, along with the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Water Alliance have provided webinars and other guidance for using a One Water approach for water management. [ 11 ] The U.S. Water Alliance also has more initiatives to support One Water, including the One Water Council to bring organizations together, [ 12 ] and Value of Water Campaign to educate about the importance of all water sources. [ 13 ]
One Water Panel helps develop strategies for integrating water source development and management to more effectively meet present and future water needs and address climate change impacts. [ 14 ]
The National Association of Clean Water Agencies (NACWA) and Association of Metropolitan Water Agencies (AMWA) have developed a campaign for Affordable Water, Resilient Communities to increase political awareness around water issues. [ 15 ]
American Rivers uses a holistic approach to water management and hosted a 2-day conference to collect ideas for helping cities adapt an integrated water management approach in 2016. [ 8 ]
The Southeast Michigan Council of Governments (SEMCOG) has a One Water Program to educate about water use and systems and their interrelationships and as a water stewardship approach. They hosted events at the 2023 Great Lakes and Fresh Water Week, posted videos to showcase benefits of a one-water approach, and have a series of articles. [ 16 ]
The University of Illinois Urbana-Champaign includes One Water among five curricula toward a Bachelor of Science degree in Environmental engineering . Their One Water program emphasizes application of physical, chemical, and biological principles to design innovative water quality control processes for safe and reliable community or household drinking water, sanitation, stormwater management, and resource (water, nutrient, energy) recovery systems. [ 4 ]
One Water concepts are also used in building planning and sustainable development. Blue Hole Primary School, Texas used One Water concepts as it built the school. [ 1 ]
Cities have developed a variety of One Water Strategies, and there is guidance and studies for helping more cities develop their plans. The Water Research Foundation and Colorado State University are developing guidance for One Water Cities (2020–2023). [ 17 ] International Water Association developed a Cities of the Future integrated water management program. [ 18 ]
The City of Los Angeles launched the One Water LA 2040 Plan, an integrated and unified approach to sustainably manage all water resources—surface water, groundwater, potable water, wastewater, recycled water, and stormwater. [ 19 ]
Palo Alto is developing a One Water Plan as part of their climate Action-Protection and Adaptation planning priority. [ 20 ]
San Francisco, California, has a broad OneWater SF Vision with many resources into their water planning, including “water, energy, financial, human, community partnerships and natural resources” [ 21 ]
Denver, Colorado, adopted a One Water Plan in September 2021. [ 22 ] [ 23 ]
Wake County, North Carolina started a One Water Plan for its municipalities with a public visioning survey in May 2023. [ 24 ] [ 25 ]
Milwaukee, Wisconsin, has a One Water approach with information tailored to different audiences at #onewaterourwater [ 26 ]
Vancouver, British Columbia, uses a One Water Approach to address changes in its watershed. [ 27 ]
One Water Panel Honolulu received the US Water Prize for the Outstanding Public Sector Category, US Water Alliance in 2022 [ 28 ]
One Water Summits were held in 2015, 2017 (New Orleans, Louisiana), and 2018 (Twin Cities, Minnesota) [ 8 ]
A City Summit for cities to adapt One Water plans was held in Charlotte, North Carolina November 15–18, 2017. [ 29 ]
Reclaimed water
Water conservation | https://en.wikipedia.org/wiki/One_Water_(water_management) |
In quantum information , the one clean qubit model of computation is performed an n {\displaystyle n} qubit system with one pure state and n − 1 {\displaystyle n-1} maximally mixed states . [ 1 ] This model was motivated by highly mixed states that are prevalent in nuclear magnetic resonance quantum computers. It's described by the density matrix ρ = | 0 ⟩ ⟨ 0 | ⊗ I 2 n − 1 {\displaystyle \rho =\left|0\right\rangle \langle 0|\otimes {\frac {I}{2^{n-1}}}} , where I {\displaystyle I} is the identity matrix . In computational complexity theory , DQC1 ; also known as the deterministic quantum computation with one clean qubit is the class of decision problems solvable by a one clean qubit machine in polynomial time, upon measuring the first qubit, with an error probability of at most 1/poly(n) for all instances. [ 2 ]
The most standard definition of DQC1 requires that measuring the output qubit correctly accepts or rejects the input, with error at most 1 / q ( n ) {\displaystyle 1/q(n)} for specified some polynomial q , given a gap in acceptance probabilities of [ 0 , 1 / 2 − 1 / q ( n ) ] {\displaystyle [0,1/2-1/q(n)]} for NO instances and [ 1 / 2 + 1 / q ( n ) , 1 ] {\displaystyle [1/2+1/q(n),1]} for YES instances. Most probabilistic classes, such as BPP , BQP , and RP are agnostic to the precise probability gap, because any polynomial acceptance gap can be amplified to a fixed gap such as (1/3,2/3). A notable outlier is PP , which permits exponentially small gaps.
DQC1 does not admit an obvious notion of parallel composability or amplification: there is no clear construction to transform a circuit with, say, a (2/5,3/5) acceptance gap into a more accurate (1/5,4/5) acceptance gap.
It is known that DQC1 offers composability in the sense that the "one" clean qubit can be upgraded to "two" clean qubits, or even l o g ( n ) {\displaystyle log(n)} many clean qubits, without modifying the class [ 3 ] Computation with Unitaries and One Pure Qubit.
D. J. Shepherd. [ 4 ] It is also not strengthened by measuring all of these clean qubits (as opposed to just the first clean qubit).
Because as many as O ( log ( n ) ) {\displaystyle O(\log(n))} qubits are permitted, [ 3 ] DQC1 contains all logspace computations. It is closed under ⊕ {\displaystyle \oplus } L reductions as well. It is not known to contain BPP or even P. It is contained in BQP, and it is conjectured that this is containment is strict.
It is known that simulating the sampling problem even for 3 output qubits is classically hard, in the sense that it would imply a PH collapse . [ 5 ]
The term DQC1 has been used to instead refer to decision problems solved by a polynomial time classical circuit that adaptively makes queries to polynomially many DQC1 circuits. [ 6 ] In this sense of use, the class naturally contains all of BPP, and the power of the class is focused on the "inherently quantum" power.
Trace estimation is complete for DQC1 . [ 7 ] Let U {\displaystyle U} be a unitary 2 n × 2 n {\displaystyle 2^{n}\times 2^{n}} matrix. Given a state | ψ ⟩ {\displaystyle |\psi \rangle } , the Hadamard test can estimate ⟨ ψ | U | ψ ⟩ {\displaystyle \left\langle \psi \right|U\left|\psi \right\rangle } where 1 2 + 1 2 R e ( ⟨ ψ | U | ψ ⟩ ) {\textstyle {\frac {1}{2}}+{\frac {1}{2}}{\mathcal {Re}}(\left\langle \psi \right|U\left|\psi \right\rangle )} is the probability that the measured clean qubit is 0. I / 2 n {\displaystyle I/2^{n}} mixed state inputs can be simulated by letting | ψ ⟩ {\displaystyle |\psi \rangle } be chosen uniformly at random from 2 n {\displaystyle 2^{n}} computational basis states. When measured, the probability that the final result is 0 is [ 2 ] 1 2 n ∑ x ⊂ { 0 , 1 } n 1 + R e ⟨ x | U | x ⟩ 2 = 1 2 + 1 2 R e ( T r ( U ) ) 2 n . {\displaystyle {\frac {1}{2^{n}}}\sum _{x\subset \{0,1\}^{n}}{\frac {1+{\mathcal {Re}}\left\langle x\right|U\left|x\right\rangle }{2}}={\frac {1}{2}}+{\frac {1}{2}}{\frac {{\mathcal {Re}}(Tr(U))}{2^{n}}}.} To estimate the imaginary part of the T r ( U ) {\displaystyle Tr(U)} , the clean qubit is initialized to 1 2 ( | 0 ⟩ − i | 1 ⟩ ) {\textstyle {\frac {1}{\sqrt {2}}}\left(\left|0\right\rangle -i\left|1\right\rangle \right)} instead of 1 2 ( | 0 ⟩ + | 1 ⟩ ) {\textstyle {\frac {1}{\sqrt {2}}}\left(\left|0\right\rangle +\left|1\right\rangle \right)} .
In addition to unitary trace estimation, estimating a coefficient in the Pauli decomposition of a unitary and approximating the Jones polynomial at a fifth root of unity are also DQC1-complete . In fact, trace estimation is a special case of Pauli decomposition coefficient estimation. [ 8 ] | https://en.wikipedia.org/wiki/One_clean_qubit |
One half is the multiplicative inverse of 2 . It is an irreducible fraction with a numerator of 1 and a denominator of 2. It often appears in mathematical equations , recipes and measurements .
One half is one of the few fractions which are commonly expressed in natural languages by suppletion rather than regular derivation. In English , for example, compare the compound "one half" with other regular formations like "one-sixth".
A half can also be said to be one part of something divided into two equal parts. It is acceptable to write one half as a hyphenated word, one-half .
One half is the rational number that lies midway between 0 and 1 on the number line . Multiplication by one half is equivalent to division by two , or "halving"; conversely, division by one half is equivalent to multiplication by two, or "doubling".
A number raised to the power of one half is equal to its square root .
The area of a triangle is one half its base and altitude (or height).
The gamma function evaluated at one half is the square root of pi .
It has two different decimal representations in base ten , the familiar 0.5 {\displaystyle 0.5} and the recurring 0.4 9 ¯ {\displaystyle 0.4{\overline {9}}} [ dubious – discuss ] , with a similar pair of expansions in any even base ; while in odd bases, one half has no terminating representation.
The Bernoulli number B 1 {\displaystyle B_{1}} has the value ± 1 2 {\displaystyle \pm {\tfrac {1}{2}}} (its sign depending on competing conventions).
The Riemann hypothesis is the conjecture that every nontrivial complex root of the Riemann zeta function has a real part equal to 1 2 {\displaystyle {\tfrac {1}{2}}} .
The "one-half" symbol has its own code point as a precomposed character in the Latin-1 Supplement block of Unicode , rendering as ½ .
The reduced size of this symbol may make it illegible to readers with relatively mild visual impairment ; consequently the decomposed forms 1 ⁄ 2 or 1 / 2 may be more appropriate. | https://en.wikipedia.org/wiki/One_half |
In statistics , the one in ten rule is a rule of thumb for how many predictor parameters can be estimated from data when doing regression analysis (in particular proportional hazards models in survival analysis and logistic regression ) while keeping the risk of overfitting and finding spurious correlations low. The rule states that one predictive variable can be studied for every ten events. [ 1 ] [ 2 ] [ 3 ] [ 4 ] For logistic regression the number of events is given by the size of the smallest of the outcome categories, and for survival analysis it is given by the number of uncensored events. [ 3 ] In other words: for each feature we need 10 observations/labels.
For example, if a sample of 200 patients is studied and 20 patients die during the study (so that 180 patients survive), the one in ten rule implies that two pre-specified predictors can reliably be fitted to the total data. Similarly, if 100 patients die during the study (so that 100 patients survive), ten pre-specified predictors can be fitted reliably. If more are fitted, the rule implies that overfitting is likely and the results will not predict well outside the training data . It is not uncommon to see the 1:10 rule violated in fields with many variables (e.g. gene expression studies in cancer), decreasing the confidence in reported findings. [ 5 ]
A "one in 20 rule" has been suggested, indicating the need for shrinkage of regression coefficients, and a "one in 50 rule" for stepwise selection with the default p-value of 5%. [ 4 ] [ 6 ] Other studies, however, show that the one in ten rule may be too conservative as a general recommendation and that five to nine events per predictor can be enough, depending on the research question. [ 7 ]
More recently, a study has shown that the ratio of events per predictive variable is not a reliable statistic for estimating the minimum number of events for estimating a logistic prediction model. [ 8 ] Instead, the number of predictor variables, the total sample size (events + non-events) and the events fraction (events / total sample size) can be used to calculate the expected prediction error of the model that is to be developed. [ 9 ] One can then estimate the required sample size to achieve an expected prediction error that is smaller than a predetermined allowable prediction error value. [ 9 ]
Alternatively, three requirements for prediction model estimation have been suggested: the model should have a global shrinkage factor of ≥ 0.9, an absolute difference of ≤ 0.05 in the model's apparent and adjusted Nagelkerke R 2 , and a precise estimation of the overall risk or rate in the target population. [ 10 ] The necessary sample size and number of events for model development are then given by the values that meet these requirements. [ 10 ]
For highly correlated input data the one-in-10 rule (10 observations or labels needed per feature) may not be directly applicable due to the high correlation of the features: For images there is a rule of thumb that per class 1000 examples are needed. [ 11 ] This would mean that for a binary classification of images (with fictive 1000 pixel x 1000 pixel per image, i.e. 1 000 000 features per image), we would only require 2000 labels /1 000 0000 pixel = 0.002 labels per pixel or 0.002 labels per feature. This is however only due to the high (spatial) correlation of pixels. | https://en.wikipedia.org/wiki/One_in_ten_rule |
" One size fits all " is a description for a product that would fit in all instances. The term has been extended to mean one style or procedure would fit in all related applications. It is an alternative for "Not everyone fits the mold." [ 1 ] [ 2 ] It has been in use for over five decades. There are both positive and negative uses of the phrase.
The term "one size fits all" has been used as a common, cliche phrase for over 50 years. [ when? ] [ citation needed ]
There are several positive views of the phrase "one size fits all":
There are many negative views of the phrase "one size fits all" including:
Politically, the phrase has come to mean that methods of administration or political beliefs in one country should not necessarily be applied to another. | https://en.wikipedia.org/wiki/One_size_fits_all |
In the field of psychology , the subfield of oneirology ( / ɒ n ɪ ˈ r ɒ l ə dʒ i / ; from Ancient Greek ὄνειρον (oneiron) ' dream ' and -λογία ( -logia ) ' the study of ' ) is the scientific study of dreams . Research seeks correlations between dreaming and knowledge about the functions of the brain, as well as an understanding of how the brain works during dreaming as pertains to memory formation and mental disorders . The study of oneirology can be distinguished from dream interpretation in that the aim is to quantitatively study the process of dreams instead of analyzing the meaning behind them.
In the 19th century, two advocates of this discipline were the French sinologists Marquis d' Hervey de Saint Denys and Alfred Maury . The field gained momentum in 1952, when Nathaniel Kleitman and his student Eugene Aserinsky discovered regular cycles. A further experiment by Kleitman and William C. Dement , then another medical student, demonstrated the particular period of sleep during which electrical brain activity, as measured by an electroencephalograph (EEG), closely resembled that of waking, in which the eyes dart about actively. This kind of sleep became known as rapid eye movement ( REM ) sleep, and Kleitman and Dement's experiment found a correlation of 0.80 between REM sleep and dreaming.
Research into dreams includes exploration of the mechanisms of dreaming, the influences on dreaming, and disorders linked to dreaming. Work in oneirology overlaps with neurology and can vary from quantifying dreams to analyzing brain waves during dreaming, to studying the effects of drugs and neurotransmitters on sleeping or dreaming. Though debate continues about the purpose and origins of dreams, there could be great gains from studying dreams as a function of brain activity. For example, knowledge gained in this area could have implications for the treatment of certain mental illnesses.
Dreaming occurs mainly during REM sleep , and brain scans recording brain activity have witnessed heavy activity in the limbic system and the amygdala during this period. Though current research has reversed the myth that dreaming occurs only during REM sleep, it has also shown that the dreams reported in non-rapid eye movement ( NREM ) and REM differ qualitatively and quantitatively, suggesting that the mechanisms that control each are different. [ 1 ]
During REM sleep, researchers theorize that the brain goes through a process known as synaptic efficacy refreshment. This is observed as brain waves self-firing during sleep, in slow cycles at a rate of around 14 Hz, and is believed to serve the purpose of consolidating recent memories and reinforcing old memories. In this type of brain stimulation, the dreaming that occurs is a by-product of the process. [ 2 ]
During normal sleep cycles , humans alternate between normal, NREM sleep and REM sleep. The brain waves characteristic of dreaming that are observed during REM sleep are the most commonly studied in dream research because most dreaming occurs during REM sleep. [ 1 ]
In 1952, Eugene Aserinsky discovered REM sleep while working in the surgery of his PhD advisor. Aserinsky noticed that the sleepers' eyes fluttered beneath their closed eyelids, later using a polygraph machine to record their brain waves during these periods. In one session, he awakened a subject who was wailing and crying out during REM and confirmed his suspicion that dreaming was occurring. [ 3 ] [ page needed ] In 1953, Aserinsky and his advisor published the ground-breaking study in Science . [ 4 ]
Accumulated observation shows that dreams are strongly associated with REM sleep, during which an electroencephalogram shows brain activity to be most like wakefulness. While REMS is associated with dreaming, not all REMS periods result in reported dreams, and not all dreams occur during REMS. [ 5 ] Participant-nonremembered dreams during NREM are normally more mundane in comparison. [ 6 ] During a typical lifespan, a human spends a total of about six years dreaming [ 7 ] (which is about two hours each night). [ 8 ] Most dreams last only 5 to 20 minutes. [ 7 ] It is unknown where in the brain dreams originate, if there is a single origin for dreams, if multiple portions of the brain are involved, or what the purpose of dreaming is for the body or mind.
During REM sleep, the release of certain neurotransmitters is completely suppressed. As a result, motor neurons are not stimulated, a condition known as REM atonia . This prevents dreams from resulting in dangerous movements of the body . [ 9 ] [ 10 ]
Animals have complex dreams and are able to retain and recall long sequences of events while they are asleep. [ 11 ] [ 12 ] Studies show that various species of mammals and birds experience REM during sleep, [ 13 ] and follow the same series of sleeping states as humans. [ 11 ]
The discovery that dreams take place primarily during a distinctive electrophysiological state of sleep (REM), which can be identified by objective criteria, led to rebirth of interest in this phenomenon. When REM sleep episodes were timed for their duration and subjects awakened to make reports before major editing or forgetting could take place, it was determined that subjects accurately matched the length of time they judged the dream narrative to occupy with the length of REM sleep that preceded the awakening. This close correlation of REM sleep and dream experience was the basis of the first series of reports describing the nature of dreaming: that it is a regular nightly occurrence, rather than an occasional phenomenon, and that it is a high-frequency activity within each sleep period occurring at predictable intervals of approximately every 60–90 minutes in all humans throughout the life span. [ citation needed ]
REM sleep episodes and the dreams that accompany them lengthen progressively across the night, with the first episode the shortest, of approximately 10–12 minutes duration, and the second and third episodes increasing to 15–20 minutes. Dreams at the end of the night may last typically 15 minutes, although these may be experienced as several distinct stories due to momentary arousals interrupting sleep as the night ends. [ citation needed ]
Dream reports can normally be made 50% of the time when an awakening occurs prior to the end of the first REM period. This rate of retrieval is increased to about 99% when awakenings occur during the last REM period of the night. This increase in the ability to recall appears to be related to intensification across the night in the vividness of dream imagery, colors and emotions. The dream story itself in the last REM period is farthest from reality, containing more bizarre elements, and it is these properties, coupled with the increased likelihood of morning waking review to take place, that heighten the chance of recall of the last dream. [ citation needed ]
The definition of dream used in quantitative research is defined through four base components:
In summary, a dream, as defined by G. William Domhoff and Adam Schneider, is "a report of a memory of a cognitive experience that happens under the kinds of conditions that are most frequently produced in a state called 'sleep. ' " [ 14 ]
Authentic dreams are defined by their tendency to occur "within the realm of experience" [ 2 ] and reflect actual memories or experiences the dreamer can relate to. Authentic dreams are believed to be the side effect of synaptic efficacy refreshment that occurs without errors. [ 15 ] Research suggests that the brain stimulation that occurs during dreaming authentic dreams is significant in reinforcing neurological pathways, serving as a method for the mind to " rehearse " certain things during sleep.
Illusory dreams are defined as dreams that contain impossible, incongruent, or bizarre content and are hypothesized to stem from memory circuits accumulating efficacy errors. In theory, old memories having undergone synaptic efficacy refreshment multiple times throughout one's lifetime result in accumulating errors that manifest as illusory dreams when stimulated. Qualities of illusory dreaming have been linked to delusions observed in mental disorders. [ 2 ] Illusory dreams are believed to most likely stem from older memories that experience this accumulation of errors in contrast to authentic dreams that stem from more recent experiences.
One aspect of dreaming studied is the capability to externally influence the contents of dreams with various stimuli. One such successful connection was made to the olfactory system , influencing the emotions of dreams through a smell stimulus. Their research has shown that the introduction of a positive smelling stimulus (roses) induced positive dreams while negative smelling stimulus (rotten eggs) induced negative dreams. [ 16 ]
Though there is much debate within the field about the purpose of dreaming, a leading theory involves the consolidation of memories and experiences that occurs during REM sleep. The electric involuntary stimulus the brain undergoes during sleep is believed to be a basis for a majority of dreaming. Research suggests that dreams, especially during REM sleep, help consolidate memories by integrating new information with existing memories. This process may prioritize emotionally significant or unresolved experiences. [ 17 ]
The link between memory, sleep, and dreams becomes more significant in studies analyzing memory consolidation during sleep. Research has shown that NREM sleep is responsible for the consolidation of facts and episodes in contrast to REM sleep that consolidates more emotionally related aspects of memory. [ 18 ] The correlation between REM and emotional consolidation could be interpreted as the reason why dreams are of such an emotional nature and produce strong reactions from humans.
In addition to the conscious role people are aware of memory and experience playing in dreaming, unconscious effects such as health of relationships factor into the types of dreams the brain produces. Of the people analyzed, those suffering from " insecure attachments " were found to dream with more frequency and more vividly than those who were evaluated to have " secure attachments ". [ 19 ]
Correlations between the usage of drugs and dreaming have been documented, particularly the use of drugs, such as sedatives , and the suppression of dreaming because of drugging effects on the cycles and stages of sleep while not allowing the user to reach REM. Drugs used for their stimulating properties ( cocaine , methamphetamine , and ecstasy ) have been shown to also decrease the restorative properties of REM sleep and its duration. [ 20 ]
Dreaming disorders are difficult to quantify due to the ambiguous nature of dreaming. However, dreaming disorders can be linked to psychological disorders such as post-traumatic stress disorder expressed as nightmares . Research into dreaming also suggests similarity and links in illusory dreaming and delusions . [ 2 ]
Diagnostic symptoms include re-experiencing original trauma (s), by means of flashbacks or nightmares; avoidance of stimuli associated with the trauma; and increased arousal , such as difficulty falling or staying asleep, anger, and hypervigilance .
Links to post-traumatic stress disorder (PTSD) and dreaming have been made in studying the flashbacks or nightmares the victims would suffer. Measurement of the brain waves exhibited by the subjects experiencing these episodes showed great similarity between those of dreaming. The drugs used to treat those suffering from these symptoms of flashbacks and nightmares would suppress not only these traumatic episodes but also any other sort of dreaming function. [ 2 ]
The symptoms of schizophrenia involve abnormalities in the perception or expression of reality primarily focused on delusions and hallucinations .
The delusions experienced by those with schizophrenia have been likened to the experience of illusory dreams that have come to be interpreted by the subject as actual experiences. [ 2 ] Additional research into medication to suppress symptoms of schizophrenia have also shown to influence the REM cycle of those taking the medication and as a result influence the patterns of sleep and dreaming in the subjects. [ 21 ] | https://en.wikipedia.org/wiki/Oneirology |
Oneiromancy (from Greek όνειροϛ ( oneiros ) ' dream ' and μαντεία (manteia) ' prophecy ' ) is a form of divination based upon dreams , and also uses dreams to predict the future. Oneirogen plants may also be used to produce or enhance dream-like states of consciousness. Occasionally, the dreamer feels as if they are transported to another time or place, and this is offered as evidence they are in fact providing divine information upon their return. [ 1 ] [ 2 ]
Oneirocritic literature is the traditional (ancient and medieval) literary format of dream interpretation .
The ancient Sumerians in Mesopotamia have left evidence of dream interpretation dating back to at least 3100 BC. [ 3 ] [ 4 ] Throughout Mesopotamian history, dreams were always held to be extremely important for divination [ 4 ] [ 5 ] and Mesopotamian kings paid close attention to them. [ 4 ] [ 3 ] Gudea , the king of the Sumerian city-state of Lagash (reigned c. 2144–2124 BC), rebuilt the temple of Ningirsu as the result of a dream in which he was told to do so. [ 4 ] The standard Akkadian Epic of Gilgamesh contains numerous accounts of the prophetic power of dreams. [ 4 ] First, Gilgamesh himself has two dreams foretelling the arrival of Enkidu . [ 4 ] Later, Enkidu dreams about the heroes' encounter with the giant Humbaba . [ 4 ] Dreams were also sometimes seen as a means of seeing into other worlds [ 4 ] and it was thought that the soul, or some part of it, moved out of the body of the sleeping person and actually visited the places and persons the dreamer saw in his or her sleep. [ 6 ] In Tablet VII of the epic, Enkidu recounts to Gilgamesh a dream in which he saw the gods Anu , Enlil , and Shamash condemn him to death. [ 4 ] He also has a dream in which he visits the Underworld . [ 4 ]
The Assyrian king Ashurnasirpal II (reigned 883–859 BC) built a temple to Mamu, possibly the god of dreams, at Imgur-Enlil , near Kalhu . [ 4 ] The later Assyrian king Ashurbanipal (reigned 668– c. 627 BC) had a dream during a desperate military situation in which his divine patron, the goddess Ishtar , appeared to him and promised that she would lead him to victory. [ 4 ] The Babylonians and Assyrians divided dreams into "good", which were sent by the gods, and "bad", sent by demons. [ 5 ] A surviving collection of dream omens entitled Iškar Zaqīqu records various dream scenarios as well as prognostications of what will happen to the person who experiences each dream, apparently based on previous cases. [ 4 ] [ 7 ] Some list different possible outcomes, based on occasions in which people experienced similar dreams with different results. [ 4 ] Dream scenarios mentioned include a variety of daily work events, journeys to different locations, family matters, sex acts, and encounters with human individuals, animals, and deities. [ 4 ]
In ancient Egypt , as far back as 2000 BC, the Egyptians wrote down their dreams on papyrus . People with vivid and significant dreams were thought to be blessed and were considered special. [ 8 ] Ancient Egyptians believed that dreams were like oracles , bringing messages from the gods. They thought that the best way to receive divine revelation was through dreaming and thus they would induce (or " incubate ") dreams. Egyptians would go to sanctuaries and sleep on special "dream beds" in hope of receiving advice, comfort, or healing from the gods. [ 9 ]
The oldest oneirocritic manuscript hitherto discovered is the "Ramesside dream-book" now in the British Museum. [ 10 ] A unique exemplar of a book of dream-interpretation from pre-Hellenistic Egypt, the surviving fragments were translated into English by Kasia Szpakowska. [ 11 ]
Between the paws of the Sphinx , there is a stele describing how Thutmose IV restored the Sphinx as a result of a dream, on the promise of becoming a pharaoh .
Dream divination was a common feature of Greek and Roman religion and literature of all genres. Aristotle and Plato discuss dreams in various works. The only surviving Greco-Roman dreambook, the Oneirocritica , was written by Artemidorus . Artemidorus cites a large number of previous authors, all of whom are now lost. These include Astrampsychos, Nikephoros, Germanos, and Manuel Palaiologos. [ 12 ] [ 13 ] [ 14 ] [ 15 ] Seers who specialized at the interpretation of dreams were called enypniomantis (ἐνυπνιόμαντις) and brizomantis (βριζόμαντις). [ 16 ] [ 17 ]
Dreams occur throughout the Bible as omens or messages from God ;
In Acts 2:17, the apostle Peter quotes Joel 2:28, saying that because of the Spirit now out poured, "...your old men will dream dreams."
The pertinent material is included in the several Purāṇa-s, such as the Liṅga Purāṇa . [ 21 ]
Here, dreams about specific numbers [ 22 ] or about reading specific chapters [ 23 ] of the Qurʼan are among the chief subjects of prognostication. The most renowned of the Arabic texts of oneiromancy is the Great Book of Interpretation of Dreams , a 15th-century compilation of earlier scholarship.
Achmet is an adaptation of an Arabic book to the tastes of a European readership.
Derived from older literature, modern dream-books are still in common use in Europe and the United States, being commonly sold along with good-luck charms.
Sei Shonagon refers to having her dreams interpreted in The Pillow Book . [ 24 ]
The Taiheiki , a 14th-century war chronicle, portrays Emperor Godaigo selecting Kusunoki Masashige as the leader of his forces based on a portentous dream. [ 25 ]
The indigenous Chontal of the Mexican state of Oaxaca use Calea zacatechichi , a flowering plant, for oneiromancy by placing it under the pillow of the dreamer. Similarly, Entada rheedii is used in various African cultures. | https://en.wikipedia.org/wiki/Oneiromancy |
Oneironautics ( / ə n eɪ r oʊ ˈ n ɔː t ɪ k s / ) refers to the ability to travel within a dream on a conscious basis . Such a traveler in a dream may be called an oneironaut .
A lucid dream is one in which the dreamer is aware that they are dreaming. They are able to exert some or a complete control over the dream's characters, narrative and/or environment. Early references to the phenomenon are found in ancient Greek texts.
The idea of one person being able to consciously travel or interact within the dream of another person, known variously as " dream telepathy ", [ 1 ] [ 2 ] [ 3 ] [ 4 ] " telepathic lucid dreaming ", or " telepathic dreaming ", [ 5 ] has been explored in the realms of science and fantasy fiction; in recent works, such an interaction is often depicted as a computer-mediated psychotherapeutic action, as is the case in The Cell , and Paprika , as well as through the direct intervention of another sleeping person, as in Inception , Dreamscape , and Waking Life . The concept is also included in the fantasy series The Wheel of Time as an ability " dreamwalkers " are able to use.
A trope in such works of fiction explores the ramifications of whether the sleeping protagonist should enter the sleeping brain of another as opposed to allowing another individual to enter one's own brain; the entering of another individual's brain often results in unpleasant surprises, depending upon the mental state of the host or the preparedness of the guest. Roger Zelazny 's 1966 sci-fi novella The Dream Master , which applies computer-mediated dream telepathy in a psychotherapeutic setting, focuses on the protagonist's growing struggle to keep his balance as he enters the brain of a fellow psychotherapist who is blind, and subconsciously destructively hungers for the visual stimuli upon which dreams largely depend. | https://en.wikipedia.org/wiki/Oneironautics |
The ones' complement of a binary number is the value obtained by inverting (flipping) all the bits in the binary representation of the number. The name "ones' complement" [ 1 ] refers to the fact that such an inverted value, if added to the original, would always produce an "all ones" number (the term " complement " refers to such pairs of mutually additive inverse numbers, here in respect to a non-0 base number). This mathematical operation is primarily of interest in computer science , where it has varying effects depending on how a specific computer represents numbers.
A ones' complement system or ones' complement arithmetic is a system in which negative numbers are represented by the inverse of the binary representations of their corresponding positive numbers. In such a system, a number is negated (converted from positive to negative or vice versa) by computing its ones' complement. An N-bit ones' complement numeral system can only represent integers in the range −(2 N−1 −1) to 2 N−1 −1 while two's complement can express −2 N−1 to 2 N−1 −1. It is one of three common representations for negative integers in binary computers , along with two's complement and sign-magnitude .
The ones' complement binary numeral system is characterized by the bit complement of any integer value being the arithmetic negative of the value. That is, inverting all of the bits of a number (the logical complement) produces the same result as subtracting the value from 0.
Many early computers, including the UNIVAC 1101 , CDC 160 , CDC 6600 , the LINC , the PDP-1 , and the UNIVAC 1107 , used ones' complement arithmetic. Successors of the CDC 6600 continued to use ones' complement arithmetic until the late 1980s, and the descendants of the UNIVAC 1107 (the UNIVAC 1100/2200 series ) still do, but the majority of modern computers use two's complement .
Positive numbers are the same simple, binary system used by two's complement and sign-magnitude. Negative values are the bit complement of the corresponding positive value. The largest positive value is characterized by the sign (high-order) bit being off (0) and all other bits being on (1). The lowest negative value is characterized by the sign bit being 1, and all other bits being 0. The table below shows all possible values in a four-bit system, from −7 to +7.
Adding two values is straightforward. Simply align the values on the least significant bit and add, propagating any carry to the bit one position left. If the carry extends past the end of the word it is said to have "wrapped around", a condition called an " end-around carry ". When this occurs, the bit must be added back in at the right-most bit. This phenomenon does not occur in two's complement arithmetic.
Subtraction is similar, except that borrows, rather than carries, are propagated to the left. If the borrow extends past the end of the word it is said to have "wrapped around", a condition called an " end-around borrow ". When this occurs, the bit must be subtracted from the right-most bit. This phenomenon does not occur in two's complement arithmetic.
It is easy to demonstrate that the bit complement of a positive value is the negative magnitude of the positive value. The computation of 19 + 3 produces the same result as 19 − (−3).
Add 3 to 19.
Subtract −3 from 19.
Negative zero is the condition where all bits in a signed word are 1. This follows the ones' complement rules that a value is negative when the left-most bit is 1, and that a negative number is the bit complement of the number's magnitude. The value also behaves as zero when computing. Adding or subtracting negative zero to/from another value produces the original value.
Adding negative zero:
Subtracting negative zero:
Negative zero is easily produced in a ones' complement adder. Simply add the positive and negative of the same magnitude.
Although the math always produces the correct results, a side effect of negative zero is that software must test for negative zero.
The generation of negative zero becomes a non-issue if addition is achieved with a complementing subtractor. The first operand is passed to the subtract unmodified, the second operand is complemented, and the subtraction generates the correct result, avoiding negative zero. The previous example added 22 and −22 and produced −0.
"Corner cases" arise when one or both operands are zero and/or negative zero.
Subtracting +0 is trivial (as shown above). If the second operand is negative zero it is inverted and the original value of the first operand is the result. Subtracting −0 is also trivial. The result can be only one of two cases. In case 1, operand 1 is −0 so the result is produced simply by subtracting 1 from 1 at every bit position. In case 2, the subtraction will generate a value that is 1 larger than operand 1 and an end-around borrow . Completing the borrow generates the same value as operand 1.
The next example shows what happens when both operands are plus or minus zero:
This example shows that of the four possible conditions when adding only ±0, an adder will produce −0 in three of them. A complementing subtractor will produce −0 only when the first operand is −0 and the second is 0. | https://en.wikipedia.org/wiki/Ones'_complement |
The onion test is a way of assessing the validity of an argument for a functional role for junk DNA . It relates to the paradox that would emerge if the majority of eukaryotic non-coding DNA were assumed to be functional and the difficulty of reconciling that assumption with the diversity in genome sizes among species. [ 1 ] The term "onion test" was originally proposed [ 2 ] informally in a blog post by T. Ryan Gregory in order to help clarify the debate about junk DNA . The term has been mentioned in newspapers and online media, [ 3 ] [ 4 ] scientific journal articles, [ 5 ] [ 6 ] [ 7 ] [ 8 ] and a textbook. [ 9 ] The test is defined as:
The onion test is a simple reality check for anyone who thinks they have come up with a universal function for junk DNA. Whatever your proposed function, ask yourself this question: Can I explain why an onion needs about five times more non-coding DNA for this function than a human?
Onions and their relatives vary dramatically in their genome sizes, [ 10 ] without changing their ploidy , and this gives an exceptionally valuable window on the genomic expansion junk DNA. Since the onion ( Allium cepa ) is a diploid organism having a haploid genome size of 15.9 Gb, [ 10 ] it has 4.9x as much DNA as does a human genome (3.2 Gb). Other species in the genus Allium vary hugely in DNA content without changing their ploidy. Allium schoenoprasum ( chives ) for example has a haploid genome size of 7.5 Gb, less than half that of onions, yet Allium ursinum (wild garlic) has a haploid genome size of 30.9 Gb, nearly twice (1.94x) that of onion and over four times (4.1x) that of chives. This extreme size variation between closely related species in the genus Allium is also part of the extended onion test rationale as originally defined: [ 2 ]
Further, if you think perhaps onions are somehow special, consider that members of the genus Allium range in genome size from 7 pg to 31.5 pg. So why can A. altyncolicum make do with one fifth as much regulation, structural maintenance, protection against mutagens, or [insert preferred universal function] as A. ursinum ?
Some researchers argue that the onion test is related to wider issues involving the C-value paradox and is only valid if one can justify the presumption that genome size has no bearing on organismal physiology. [ 11 ] According to Larry Moran, the onion test is not an argument for junk DNA, but an approach to assessing possible functional explanations for non-coding DNA. According to him, it asks why allium species need so much more of that proposed function than do humans, and why so much more (or less) than other closely related species of allium and does not address the variation in genome size ( C-value ) among organisms itself. [ 12 ]
According to Jonathan McLatchie, the onion test is only valid if one can justify the presumption that genome size has no bearing on organismal physiology. Long sequences of repetitive DNA can be highly relevant to an organism and can contribute to transcription delays and developmental timing mechanisms for an organism. Furthermore, he argues that there is a positive correlation between genome size and cell volume for unicellular eukaryotes like plants and protozoa and so the larger amount of DNA thus provides a selective advantage by contributing to the skeleton and volume of the nucleus of these cells. [ 11 ] Larry Moran who was actually addressed in McLatchie's post extensively replied : [ 13 ]
[the onion test is] designed as a thought experiment to test a hypothesis about the possible function of large amounts of noncoding DNA. If you think you have an explanation for why most of the human genome has a function then you should explain how that accounts for the genomes of onions. Ryan Gregory knew that most so-called explanations look very silly when you try using them to account for genome size in onion species.
Ewan Birney (then head of the ENCODE Project) explained the difference as a product of polyploidy , [ 14 ] [ 15 ] [ better source needed ] and therefore not relevant to the discussion of humans.
(re: onions etc); polyploidy and letting your repeats "go crazy" (bad piRNAs anyone) mean your genome can be v. big
Similar claims were made by John Mattick in an article defending the ENCODE project against arguments disputing the main finding of the project: [ 16 ]
The other substantive argument that bears on the issue, alluded to in the quotes that preface the Graur et al. article, and more explicitly discussed by Doolittle, is the so-called ‘C-value enigma’ , which refers to the fact that some organisms (like some amoebae, onions, some arthropods, and amphibians) have much more DNA per cell than humans, but cannot possibly be more developmentally or cognitively complex, implying that eukaryotic genomes can and do carry varying amounts of unnecessary baggage. That may be so, but the extent of such baggage in humans is unknown. However, where data is available, these upward exceptions appear to be due to polyploidy and/or varying transposon loads (of uncertain biological relevance), rather than an absolute increase in genetic complexity. Moreover, there is a broadly consistent rise in the amount of non-protein-coding intergenic and intronic DNA with developmental complexity, a relationship that proves nothing but which suggests an association that can only be falsified by downward exceptions, of which there are none known.
Freeling et al. proposed a genome balance hypothesis that presumably accounts for the C-Value Paradox and passes the Onion Test. [ 17 ] | https://en.wikipedia.org/wiki/Onion_test |
Onia
An onium (plural: onia ) is a bound state of a particle and its antiparticle . [ 1 ] These states are usually named by adding the suffix -onium to the name of one of the constituent particles (replacing an -on suffix when present), with one exception for " muonium "; a muon–antimuon bound pair is called " true muonium " to avoid confusion with old nomenclature. [ a ]
Positronium is an onium which consists of an electron and a positron bound together as a long-lived metastable state. Positronium has been studied since the 1950s to understand bound states in quantum field theory . A recent development called non-relativistic quantum electrodynamics (NRQED) used this system as a proving ground. [ 2 ]
Pionium , a bound state of two oppositely charged pions , is interesting for exploring the strong interaction . This should also be true of protonium . The true analogs of positronium in the theory of strong interactions are the quarkonium states: they are mesons made of a heavy quark and antiquark (namely, charmonium and bottomonium). Exploration of these states through non-relativistic quantum chromodynamics (NRQCD) and lattice QCD are increasingly important tests of quantum chromodynamics .
Understanding bound states of hadrons such as pionium and protonium is also important in order to clarify notions related to exotic hadrons such as mesonic molecules and pentaquark states. | https://en.wikipedia.org/wiki/Onium |
In chemistry , an onium ion is a cation formally obtained by the protonation of mononuclear parent hydride of a pnictogen (group 15 of the periodic table ), chalcogen (group 16), or halogen (group 17). The oldest-known onium ion, and the namesake for the class, is ammonium , NH + 4 , the protonated derivative of ammonia , NH 3 . [ 1 ] [ 2 ]
The name onium is also used for cations that would result from the substitution of hydrogen atoms in those ions by other groups, such as organic groups, or halogens; such as tetraphenylphosphonium , (C 6 H 5 ) 4 P + . The substituent groups may be divalent or trivalent, yielding ions such as iminium and nitrilium . [ 1 ] [ 2 ]
A simple onium ion has a charge of +1. A larger ion that has two onium ion subgroups is called a double onium ion , and has a charge of +2. A triple onium ion has a charge of +3, and so on.
Compounds of an onium cation and some other anion are known as onium compounds or onium salts .
Onium ions and onium compounds are inversely analogous to -ate ions and ate complexes :
The extra bond is added to a less-common parent hydride, a carbene analog , typically named -ene or -ylene , which is neutral with 2 fewer bonds than the more-common hydride, typically named -ane or -ine . | https://en.wikipedia.org/wiki/Onium_ion |
The OnlineHPC was a free public web service that supplied tools to deal with high performance computers and online workflow editor. OnlineHPC allowed users to design and execute workflows using the online workflow designer and to work with high performance computers – clusters and clouds. Access to high performance resources was available as directly from the service user interface, as from workflow components.
The workflow engine of the OnlineHPC service was Taverna as traditionally used for scientific workflow execution in such domains, as bioinformatics , [ 1 ] [ 2 ] cheminformatics , [ 3 ] medicine , astronomy , [ 4 ] social science , music , and digital preservation . [ 5 ]
OnlineHPC was started at the Institute for Information Transmission Problems in 2012 as a project for the institute’s researchers whose work need access to computer clusters and who are not professional programmers.
The project motivation is that there is a gap between researcher skills and competence level needed to run high performance computing . There are at least three barriers on the way to HPC:
The last requirement stops majority of even the stoutest researchers that passed first two levels. The service aims to reduce the barriers by providing a complete pre-configured set of tools required for work with computer clusters: in-browser terminal emulator, files system browser, credentials manager and massive task tool.
After a while, it became obvious that engineering and scientific tasks require a more elaborate tool suit that enables researchers to execute the flow of tasks – workflows. Unless there is a number of scientific workflow implementations, they are almost all desktop applications and thus the aim was creating an online environment with a focus on simplicity and enhanced user experience.
The project was in use in bioinformatics, [ 6 ] [ 7 ] human health, [ 8 ] telecommunications and other domains.
As of 2016-05, http://onlinehpc.com/ was unavailable.
OnlineHPC had a workflow designer available online using major browsers (Firefox, Chrome and Internet Explorer) on desktops and tablets.
Workflows in OnlineHPC included components for:
The service also had basic tools to prepare and run massive computational tasks on clusters - in-browser terminal emulator, file system browser and cluster status viewer.
Users could choose to operate existing hardware cluster or to start a configure a new cluster instance in the cloud. | https://en.wikipedia.org/wiki/OnlineHPC |
Online charging system ( OCS ) is a system allowing a communications service provider to charge their customers, in real time, based on service usage.
An event-based charging function (EBCF) is used to charge events based on their occurrence rather than their duration or volume used in the event. Typical events are SMS, MMS, purchase of content (application, game, music, video on demand, etc.).
Event-based charging function is used when the CC-Request-Type AVP = 4 i.e. for event request ex: diameter-sms or diameter-.....
Let us consider one example of Event-based charging.
1. Cost of one apple is Rupees 25/-
You pay the amount, take the apple and go. Similarly, if you send a text message it may cost you Rupee 1/- and that's it. You subscribe to Caller Ring Back Tone (CRBT) which costs you Rs.30/- a month irrespective of the number of calls you receive in a month.
So we can term event-based charging as a one-time cost or one-time occurrence cost.
The session based charging function (SBCF) is responsible for online charging of network / user sessions, e.g. voice calls, IP CAN bearers, IP CAN session or IMS sessions. [ 1 ]
Let us consider an example for session-based charging.
Utility services like electricity or water is charged based on overall usage, for a certain time duration.
You consume 'x' units of power in a month and pay for units consumed in that month. The usage may vary month to month and hence the charges. Similarly for consuming water, etc.
Hence, charging based on how much one consumes is termed as metered charging or session-based charging.
The account balance management function (ABMF) is the location of the subscriber’s account balance within the OCS.
[ 1 ] | https://en.wikipedia.org/wiki/Online_charging_system |
In computer science , online codes are an example of rateless erasure codes . These codes can encode a message into a number of symbols such that knowledge of any fraction of them allows one to recover the original message (with high probability). Rateless codes produce an arbitrarily large number of symbols which can be broadcast until the receivers have enough symbols.
The online encoding algorithm consists of several phases. First the message is split into n fixed size message blocks. Then the outer encoding is an erasure code which produces auxiliary blocks that are appended to the message blocks to form a composite message.
From this the inner encoding generates check blocks. Upon receiving a certain number of check blocks some fraction of the composite message can be recovered. Once enough has been recovered the outer decoding can be used to recover the original message.
Online codes are parameterised by the block size and two scalars , q and ε . The authors suggest q =3 and ε=0.01. These parameters set the balance between the complexity and performance of the encoding. A message of n blocks can be recovered, with high probability , from (1+3ε) n check blocks. The probability of failure is (ε/2) q+1 .
Any erasure code may be used as the outer encoding, but the author of online codes suggest the following.
For each message block, pseudo-randomly choose q auxiliary blocks
(from a total of 0.55 q ε n auxiliary blocks) to attach it to. Each auxiliary block is then the XOR of all the message blocks which have been attached to it.
The inner encoding takes the composite message and generates a stream of check blocks. A check block is the XOR of all the blocks from the composite message that it is attached to.
The degree of a check block is the number of blocks that it is attached to. The degree is determined by sampling a random distribution, p , which is defined as:
Once the degree of the check block is known, the blocks from the composite message which it is attached to are chosen uniformly.
Obviously the decoder of the inner stage must hold check blocks which it cannot currently decode . A check block can only be decoded when all but one of the blocks which it is attached to are known. The graph to the left shows the progress of an inner decoder. The x-axis plots the number of check blocks received and the dashed line shows the number of check blocks which cannot currently be used. This climbs almost linearly at first as many check blocks with degree > 1 are received but unusable. At a certain point, some of the check blocks are suddenly usable, resolving more blocks which then causes more check blocks to be usable. Very quickly the whole file can be decoded.
As the graph also shows the inner decoder falls just shy of decoding everything for a little while after having received n check blocks. The outer encoding ensures that a few elusive blocks from the inner decoder are not an issue, as the file can be recovered without them. | https://en.wikipedia.org/wiki/Online_codes |
Online engineering (OE; Sometimes also referred to as remote engineering ) is a current trend in engineering and science, aiming to allow and organize a shared use of equipment and resources, but also specialized software (such as for example simulators ).
Reasons for the growing importance of sharing engineering resources are: [ 1 ]
The International Association of Online Engineering (IAOE) is an international non-profit organization with the objective of encouraging the wider development, distribution and application of online engineering. The main forum of online engineering community is the annual International Conference on Remote Engineering and Virtual Instrumentation (REV) . | https://en.wikipedia.org/wiki/Online_engineering |
The Onsite Identification and Verification System (OIVS) is a mobile technology device used by Bangladesh's elite security force, the Rapid Action Battalion (RAB), to instantly identify and verify information about suspects and criminals in the field. [ 1 ] [ 2 ]
Prior to OIVS, when RAB arrested suspects, officers had to transport them to the nearest RAB office to manually look up their fingerprints, national IDs, and other information in databases to identify them. This delay allowed criminals using fake identities or disguise to avoid proper identification. [ 3 ]
To modernize operations and solve these problems, RAB's Communication and MIS Wing developed OIVS in 2021 as a field-based biometric and database identity verification system. [ 4 ]
OIVS consists of a portable, smartphone-like device that can be operated anywhere through an internet connection. By inputting a suspect's fingerprint, national ID number, or date of birth into the OIVS device, officers can instantly pull up identification information and criminal history from connected government databases. [ 5 ] [ 1 ]
The system currently connects to Bangladesh's National ID, passport, criminal records, and prison records databases. More databases such as driving licenses may be integrated in the future. [ 6 ]
The software for the device was made in Bangladesh, [ 7 ] and the hardware were imported from abroad. [ 8 ]
Planned OIVS upgrades include: [ 9 ]
OIVS aids RAB in: [ 8 ] [ 10 ]
As of early 2024, over 15 RAB battalions across Bangladesh have received OIVS devices and officer training. Company commanders currently operate the devices with strict security protocols. [ 11 ]
The device has been used in the 2024 national election . [ 12 ] [ 13 ]
By facilitating rapid in-field suspect identification, OIVS has increased the speed and effectiveness of RAB's operations. Within months of launch, OIVS has aided investigations into over 10 major criminal cases. [ 4 ] The technology has been credited with identifying wanted murder suspects, members of terrorist organizations, as well as unknown deceased bodies and mentally disabled people to return them to families faster. [ 2 ] [ 14 ]
The Online Insurance Verification System (OIVS) is an electronic insurance verification device mandated by the state of Alabama to enforce automobile insurance requirements. Implemented in 2013 after a pilot testing phase, OIVS allows authorized government agencies and law enforcement entities to instantly check if a vehicle has valid insurance coverage through integration with insurance company databases. [ 15 ] [ 16 ]
OIVS was established under Alabama Legislative Act 2011-688 which tasked the Alabama Department of Revenue with developing an online verification system. Insurance companies licensed in Alabama are required to cooperate by providing real-time access to auto insurance data through web services. This allows OIVS users to submit queries with details like VIN number, policy number and date, which insurance companies must confirm or deny current coverage for. [ 15 ] | https://en.wikipedia.org/wiki/Onsite_Identification_and_Verification_System |
Onsite sewage facilities ( OSSF ), also called septic systems , are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater, in areas not served by public sewage infrastructure.
A septic tank and drainfield combination is a fairly common type of on-site sewage facility in the Western world. OSSFs account for approximately 25% of all domestic wastewater treatment in the US. Onsite sewage facilities may also be based on small-scale aerobic and biofilter units, membrane bioreactors or sequencing batch reactors . These can be thought of as scaled down versions of municipal sewage treatment plants, and are also known as " package plants ." [ 1 ]
The primary mechanism of biological waste recycling in the natural environment is performed by other organisms such as animals, insects, soil microorganisms, plants, and fungi, which consume all available nutrients in the waste, leaving behind fully decomposed solids that become part of topsoil , and pure drinking water that has been stripped of everything that can possibly be consumed and utilized. This natural biological purification requires time and space to process wastes.
In virtually all engineered onsite sewage facilities, recycling and decomposition by natural organisms is still the primary mechanism of sewage disposal. Giving the organisms the time they need to decompose wastes is accomplished by establishing minimum sewage retention and settling times, and minimum liquid flow distances between sewage disposal sites and surface water or water wells .
It is normal for animals such as mice, rats, flies, and parasites to participate in the fully natural biological waste recycling process. Engineered facilities typically attempt to exclude them to prevent out of control population explosions and infestation , and prevent spread of vermin and disease .
Although the solids collected by onsite sewage facilities can potentially be used as compost to build topsoil, these solids are often incompletely decomposed due to either a lack of onsite storage space to wait for decomposition (municipal facilities), or because the solids are being stacked in a layered structure of new waste solids on top of previously decomposed solids (septic tanks and outhouses). Due to the incomplete state of decomposition, when removed from an onsite sewage facility, these solids are typically referred to as sludge rather than compost , and have powerful offensive odors arising from the microorganisms still consuming nutrients in the sludge.
Engineered facilities that use water suspension to transport solids (private septic systems and municipal facilities) typically form a floating layer in their primary settling tank, consisting of low-density liquids such as oils, buoyant solids, and soap foam. This is referred to as scum and is slowly decomposed by microorganisms, eventually falling to the bottom of the settling tank as part of the sludge. When private septic tanks are emptied of solids, the tank is typically vacuumed empty and the incompletely digested scum is added to the incompletely digested sludge, further adding to its aroma and bioactivity.
If left completely undisturbed and exposed to the open air through a vent, the sludge and scum in a settling tank will eventually be turned completely into low-odor compost. By building two tanks side by side, and diverting sewage between them, one tank can be allowed to rest while the other is in use, and the resting tank can be safely and easily cleaned out by hand before it is used again. This has been proposed as a solution for onsite sewage facilities in subsistence agriculture economies where hand labor is the most abundant.
Although human body waste is no different from the waste of any other animal, municipal facilities may be required to bury the collected solids in landfills, due to the risk of toxic contaminants placed into the shared communal sewage system, by humans unaware of the harm they are causing. Municipal facilities may also collect runoff from roadways, which contains traces of all the various chemicals used in vehicles such as brake fluid and engine oil, and those used in melting ice and snow. Private septic systems typically do not experience these issues, as the homeowner is directly aware that they must not pour toxic chemicals down the drain.
Most onsite wastewater treatment systems are of the conventional type, consisting of a septic tank and a subsurface wastewater infiltration system (SWIS). Site limitations and more stringent performance requirements have led to significant improvements in the design of wastewater treatment systems and how they are managed. Over the past 20 years the onsite wastewater treatment system (OWTS) industry has developed many new treatment technologies that can achieve high performance levels on sites with size, soil, ground water, and landscape limitations that might preclude installing conventional systems. New technologies and improvements to existing technologies are based on defining the performance requirements of the system, characterizing wastewater flow and pollutant loads, evaluating site conditions, defining performance and design boundaries, and selecting a system design that addresses these factors.
Performance requirements can be expressed as numeric criteria (e.g., pollutant concentration or mass loading limits) or narrative criteria (e.g., no odors or visible sheen) and are based on the assimilative capacity of regional ground water or surface waters, water quality objectives, and public health goals. Wastewater flow and pollutant content help define system design and size and can be estimated by comparing the size and type of facility with measured effluent outputs from similar, existing facilities. Site evaluations integrate detailed analyses of regional hydrology, geology, and water resources with site specific characterization of soils, slopes, structures, property lines, and other site features to further define system design requirements and determine the physical placement of system components.
Most of the alternative treatment technologies applied today treat wastes after they exit the septic tank; the tank retains settleable solids, grease, and oils and provides an environment for partial digestion of settled organic wastes. Post-tank treatment can include aerobic (with oxygen) or anaerobic (with no or low oxygen) biological treatment in suspended or fixed-film reactors, physical/chemical treatment, soil infiltration, fixed-media filtration , and/or disinfection. The application and sizing of treatment units based on these technologies are defined by performance requirements, wastewater characteristics, and site conditions.
Under Canadian federalism , environment is a shared power between federal and provincial governments. [ 2 ] However, waste water management mostly falls within provincial, territorial and municipal jurisdiction, while the federal government has jurisdiction over wastewater on federal land and on First Nations reserves . [ 3 ] Each province and territory has its own norms and regulations concerning the design and installation of onsite sewage facilities, such as whether a permit is required to do so and how to obtain it, the type, size and location of the system (usually according to on-site soil characteristics and other factors), etc. : [ 4 ]
The potential market volume of on-site treatment is suggested to be about 35 million population equivalents for Europe. [ 5 ]
In the United States, on site sewage facilities collect, treat, and release about 4 billion US gallons (15,000,000 m 3 ) of treated effluent per day from an estimated 26 million homes, businesses, and recreational facilities nationwide (U.S. Census Bureau, 1997). Recognition of the impacts of onsite systems on ground water and surface water quality (e.g., nitrate and bacteria contamination, nutrient inputs to surface waters) has increased interest in optimizing the systems' performance. Public health and environmental protection officials now acknowledge that onsite systems are not just temporary installations that will be replaced eventually by centralized sewage treatment services, but permanent approaches to treating wastewater for release and reuse in the environment. Onsite systems are recognized as viable, low-cost, long-term, decentralized approaches to wastewater treatment if they are planned, designed, installed, operated, and maintained properly (USEPA, 1997). NOTE: In addition to existing state and local oversight, decentralized wastewater treatment systems that serve more than 20 people might become subject to regulation under the USEPA's Underground Injection Control Program, although EPA has proposed not to include them (64FR22971:5/7/01).
Although some onsite wastewater management programs have functioned successfully in the past, problems persist. Most current onsite regulatory programs focus on permitting and installation.
Few programs address onsite system operation and maintenance, resulting in failures that lead to unnecessary costs and risks to public health and water resources. Moreover, the lack of coordination among agencies that oversee land use planning, zoning, development, water resource protection, public health initiatives, and onsite systems causes problems that could be prevented through a more cooperative approach. Effective management of onsite systems requires rigorous planning, design, installation, operation, maintenance, monitoring, and controls.
State and tribal agencies report that onsite septic systems currently constitute the third most common source of groundwater pollution and that these systems have failed because of inappropriate siting or design or inadequate long-term maintenance (USEPA, 1996a). In the 1996 Clean Water Needs Survey (USEPA, 1996b), states and tribes also identified more than 500 communities as having failed septic systems that have caused public health problems. The discharge of partially treated sewage from malfunctioning onsite systems was identified as a principal or contributing source of degradation in 32 percent of all harvest-limited shellfish growing areas. Onsite wastewater treatment systems have also contributed to an overabundance of nutrients in ponds, lakes, and coastal estuaries, leading to the excessive growth of algae and other nuisance aquatic plants (USEPA, 1996b). In addition, onsite systems contribute to contamination of drinking water sources. USEPA estimates that 168,000 viral illnesses and 34,000 bacterial illnesses occur each year as a result of consumption of drinking water from systems that rely on improperly treated ground water. Malfunctioning septic systems have been identified as one potential source of ground water contamination (USEPA, 2000).
In 2022, trials were underway on Cape Cod, Massachusetts of septic systems that reduce nitrogen pollution using wood chips and limestone. [ 6 ] | https://en.wikipedia.org/wiki/Onsite_sewage_facility |
Ontogenetic niche shift (abbreviated ONS ) [ 1 ] is an ecological phenomenon where an organism (usually an animal) changes its diet or habitat during its ontogeny (development). [ 2 ] During the ontogenetic niche shifting an ecological niche of an individual changes its breadth and position. [ 3 ] The best known representatives of taxa that exhibit some kind of the ontogenetic niche shift are fish (e.g. migration of so-called diadromous fish between saltwater and freshwater for purpose of breeding [ 2 ] ), insects (e.g. metamorphosis between different life stages; such as larva , pupa and imago [ 2 ] ) and amphibians (e.g. metamorphosis from tadpole to adult frog [ 2 ] ). [ 4 ] A niche shift is thought to be determined genetically , while also being irreversible. [ 5 ] Important aspect of the ONS is the fact, that individuals of different stages of a population (e.g. of various age or size) utilize different kind of resources and habitats. [ 6 ] [ 7 ] The term was introduced in a 1984 paper by biologists Earl E. Werner and James F. Gilliam . [ 1 ] [ 8 ]
The ontogenetic niche shift is thought to be determined genetically , while also being irreversible. [ 5 ] In complex natural systems the ONS happens multiple times in lifetime of an individual (in some examples the ontogenetic niche shifting can occur continuously). [ 4 ] The ontogenetic niche shift varies across species; in some it is hardly visible and gradual (for example a change in diet or in size in mammals and reptiles ), while in others it is obvious and abrupt (the metamorphosis of insects, which often results in changing habitat, diet and other ecological conditions). [ 5 ] [ 9 ] One of the studies suggests that differences in the ONS across species could be (at least to some degree) explained by diversity of traits and functional roles of a species. As a consequence differences in ontogenetic niche shifting are thought to follow some general patterns. [ 10 ]
It is thought that almost every organism shows some kind of ontogenetic niche shift. The ONS, which is responsible for causing a noticeable phenotypic variation among individuals of the same species, plays important role in structuring communities and influencing their inside dynamics. [ 4 ] In some cases individuals undergoing the ONS, in which they change their habitat, become a (mobile) link between two different communities (for example via flow of energy , matter and nutrients ). [ 11 ] A stage structure of a population can result in various stages interacting with different representatives of a community or even with individuals of other communities, [ 2 ] [ 12 ] thus having a distinct ecological role from other life-history stages of the same population. [ 13 ] Theoretical models, where communities are stage-structured, propose the ontogenetic niche shifting of studied organisms is influencing the whole community (especially its resilience and disturbance responses). [ 4 ]
The most apparent consequence of the ontogenetic niche shifting is a reduction of competition between different stages of the same population. Because of the ONS individuals of different age or size do not compete for food, materials and other habitat resources. [ 6 ] Different stages of the same population also have different trophic effects on food web of a community. [ 7 ] A division of a population on distinct life-history stages is useful and evident, when there is a lack of resources for one stage (for example when juveniles do not get enough resources for themselves). In that case a lacking stage will have higher mortality rate . [ 6 ]
The ONS is of great importance for survival of populations. Researchers noticed that many species exhibit the ontogenetic niche shifting at different times and in a lot of examples the ONS occurred as a response to various abiotic and biotic environmental factors . It is thought that the ontogenetic niche shift could be an adaptive response to changing conditions in individual's habitat. Authors of the life history theory predicted that organisms can affect the time of their ontogenetic niche shifting. While individuals living in favorable conditions would usually delay their ONS to successive ecological niche, organisms living in a niche with poor conditions typically advance to a further niche. [ 2 ]
Understanding the ontogenetic niche shifting in different species and its impact on the whole community is important when studying a biodiversity and ecosystem functioning. [ 4 ] It is thought to be useful when dealing with populations threatened by anthropogenic disturbances [ 4 ] [ 13 ] and environmental changes . [ 10 ] [ 13 ]
Even though the occurrence of ontogenetic niche shifting is thought to be widely distributed, the best known representative taxa with extensively studied ONS are insects and a few groups of vertebrates , especially fish and amphibians, where individuals often change their habitat as well as a lot of other aspects of their niche during the development. The less pronounced ontogenetic niche shifting can be seen in many other taxa, where their habitat stays the same. Usually the ONS in those species is evident, when looking at resources being used by organisms of the same species but various ages or size classes (for example a change in their diet). [ 2 ]
The ontogenetic niche shifting, which is connected with extreme habitat changes, can be seen among insects . [ 2 ] Individuals of taxon Insecta are known to exhibit one of the various types of metamorphosis , the best studied being hemimetabolism (where an insect passes three life stages; egg , nymph and imago ) and holometabolism (characterized with four life stages of an insect; egg, larva , pupa and imago). [ 14 ] Nutritional niches and their shifting during a ontogeny can be accurately measured by using a stable isotopic signature of animals. [ 15 ] [ 16 ] Such method has been used in studying the ONS in gastropods , such as field slugs . [ 15 ]
The ONS similar to that among insects happens in amphibian taxa, [ 2 ] the best known being frogs , which start as an egg and then hatch into a larval stage called the tadpole . [ 17 ] Tadpoles exhibit many differences that distinguish them from an adult stage of a frog; most species' tadpoles are aquatic , they usually possess external gills and primarily feed with plant material (even though there are some exceptions that consume dead animal flesh or mixed diet). [ 18 ] Another well studied example of the ONS occurs in fish, that exhibit diadromous behaviour . Diadromous fish species drastically change their habitat, when they set out on a journey from sea (saltwater) to rivers (freshwater) and vice versa. [ 2 ] A lot of freshwater fish species show the ONS in their diet, when they switch from preying on plankton to performing benthivory . [ 5 ]
The ONS may not be so visible in reptiles , even though these vertebrates do utilize it. The ontogenetic niche shifting was studied in American alligator ( Alligator mississippiensis ), which is ideal for studying ecological aspects of ONS because of many distinct size stages in a population. Alligators were switching their habitat niche between hydrologically isolated, seasonal wetlands and riverine systems. The study has shown that riverine systems were populated primarily with adults and subadults of both sexes , that used the area as a non-nesting habitat. On the other hand, juveniles and adult females were found on seasonal wetlands, which served as a nursery and nesting sites respectively. [ 11 ]
Good example of the ONS in birds are big seabirds , such as albatrosses , which spend some of their time as fully oceanic birds and when sexually mature begin to visit breeding grounds . Immature juveniles usually stay in subtropical water, where they occupy high trophic levels . Researchers noticed that young birds progressively direct towards lower trophic positions when they are coming closer to sexual maturity. After time they take on an isotopic niche of an adult bird. [ 19 ]
The ontogenetic niche shifting is a concept widely studied in paleontology and paleozoology . Large non-avian dinosaurs are known to have had exhibited one of the most intensive ontogenetic niche shifting, as they were hatched from an egg and had to experience big size shifts during their ontogeny. [ 20 ] One of the problems, connected with understanding Mesozoic dinosaur fauna was lack of so-called mesocarnivores . It is predicted the ontogenetic niche shift is an answer, because carnivorous dinosaurs started out as small hatchlings and progressed towards adult size, while occupying different successive niches and limiting trophic species diversity. Juvenile individuals of megatheropods are thought to occupy mesocarnivore niche. [ 21 ]
The ontogenetic niche shifting is primarily studied in animals, but there are some studies that deal with the ONS in plants . [ 3 ] [ 22 ] [ 23 ] One of the ONSs studied in plants is changing of a regeneration niche. Authors of the paper noticed that during the ontogeny the regeneration niche of Acer opalus , the Italian maple, had shrinked. It is thought such ontogenetic niche shift was mainly a consequence of herbivory , the depth of the litter layer and presence of other plants (especially adult trees and shrubs). [ 23 ] | https://en.wikipedia.org/wiki/Ontogenetic_niche_shift |
Ontogeny (also ontogenesis ) is the origination and development of an organism (both physical and psychological, e.g., moral development [ 1 ] ), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan.
Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny , which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). [ 2 ] While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes [ 3 ] (see evolutionary developmental biology and recapitulation theory ), individual organisms develop (ontogeny), while species evolve (phylogeny).
Ontogeny, embryology and developmental biology are closely related studies and those terms are sometimes used interchangeably. Aspects of ontogeny are morphogenesis , the development of form and shape of an organism; tissue growth; and cellular differentiation . The term ontogeny has also been used in cell biology to describe the development of various cell types within an organism. [ 4 ] Ontogeny is an important field of study in many disciplines, including developmental biology , cell biology , genetics , developmental psychology , developmental cognitive neuroscience , and developmental psychobiology . Ontogeny is used in anthropology as "the process through which each of us embodies the history of our own making". [ 5 ]
The word ontogeny comes from the Greek on meaning a being, individual; and existence, and from the suffix -geny from the Greek - geniea , meaning genesis, origin, and mode of production. [ 6 ]
The term ontogeny was coined by Ernst Haeckel , a German zoologist and evolutionist in the 1860s. Haeckel, born in Germany on February 16, 1834, was also a strong supporter of Darwinism . Haeckel suggested that ontogeny briefly and sometimes incompletely recapitulated or repeated phylogeny in his 1866 book, Generelle Morphologie der Organismen ("General Morphology of Organisms"). Even though his book was widely read, the scientific community was not very convinced or interested in his ideas, so he turned to producing more publications to get more attention. [ 7 ] In 1866, Haeckel and others imagined development as producing new structures after earlier additions to the developing organism have been established. He proposed that individual development followed developmental stages of previous generations and that the future generations would add something new to this process, and that there was a causal parallelism between an animal's ontogeny and phylogeny. In addition, Haeckel suggested a biogenetic law that ontogeny recapitulates phylogeny, based on the idea that the successive and progressive origin of new species was based on the same laws as the successive and progressive origin of new embryonic structures. According to Haeckel, development produced novelties, and natural selection would eliminate species that had become outdated or obsolete. Though his view of development and evolution wasn't justifiable, future embryologists tweaked and collaborated with Haeckel's proposals and showed how new morphological structures can occur by the hereditary modification of embryonic development. [ 8 ] [ 9 ] Marine biologist Walter Garstang reversed Haeckel's relationship between ontogeny and phylogeny, stating that ontogeny creates phylogeny, not recapitulates it. [ 10 ]
A seminal 1963 paper by Nikolaas Tinbergen named ontogeny as one of the four primary questions of biology, along with Julian Huxley's three others: causation, survival value and evolution. [ 11 ] Tinbergen emphasized that the change of behavioral machinery during development was distinct from the change in behavior during development. We can conclude that the thrush itself, i.e. its behavioral machinery, has changed only if the behavior change occurred while the environment was held constant...When we turn from description to causal analysis, and ask in what way the observed change in behavior machinery has been brought about, the natural first step is to try and distinguish between environmental influences and those within the animal...In ontogeny the conclusion that a certain change is internally controlled (is 'innate') is reached by elimination . [ 12 ] Tinbergen was concerned that the elimination of environmental factors is difficult to establish, and the use of the word innate is often misleading.
Development of an organism happens through fertilization, cleavage, blastulation, gastrulation, organogenesis, and metamorphosis into an adult. Each species of animal has a slightly different journey through these stages, since some stages might be shorter or longer when compared to other species, and where the offspring develops is different for each animal type (e.g., in a hard egg shell, uterus, soft egg shell, on a plant leaf, etc.). [ 13 ]
In humans, the process of fetal development starts after sperm fertilizes an egg and they fuse together, kickstarting embryonic development . The fusion of egg and sperm into a zygote changes the surrounding membrane to not allow any more sperm to penetrate the egg, so multiple fertilizations can be prevented. Fusion of a zygote also activates the egg so it can begin undergoing cell division. Each animal species might not have specifically a sperm and an egg, but two gametes that contain half of the species' typical genetic material and the membranes of these gametes fuse to start creating an offspring. [ 14 ]
Not long after successful fertilization by sperm, the zygote undergoes many mitotic divisions , which are also non-sexual cell divisions. Cleavage is the process of cell division, so the starting zygote becomes a collection of identical cells which is a morula and contains cells called blastomeres. [ 15 ] Cleavage prepares the zygote to become an embryo, which is from 2 weeks to 8 weeks after conception (fertilization) in humans. [ 16 ]
After the zygote has become an embryo, it continues dividing into a hollow sphere of cells, which is a blastula . These outer cells form a single epithelial layer, the blastoderm, that essentially encases the fluid-filled inside that is the blastocoel. The figure to the right shows the basic process that is modified in different species. Blastulation differs slightly in different species, but in mammals, the eight-cell stage embryo forms into a slightly different type of blastula, called a blastocyst. [ 17 ] Other species such as sea stars , frogs , chicks , and mice have all the same structures in this stage, yet the orientation of these features differs, plus these species have additional types of cells in this stage. [ 18 ]
After blastulation, the single-layered blastula expands and reorganizes into multiple layers, a gastrula (seen in the figure to the right). Reptiles , birds and mammals are triploblastic organisms, meaning the gastrula comprises three germ layers ; the endoderm (inner layer), mesoderm (middle layer), and ectoderm (outer layer). [ 15 ] As seen in the figure below, each germ layer will become multi-potent stem cells that can become a specific tissue depending on the germ layer and is what happens in humans. This differentiation of germ layers differs slightly, because not all of the organs and tissues below are in all organisms, but corresponding body systems can be substituted in place of these. [ 19 ]
In the figure below, human germ cells are able to differentiate into the specific organs and tissues they become later on in life. Germ cells are able to migrate to their final locations to rearrange themselves and some organs are made of two germ layers; one for the outside, the other for the inside. [ 20 ] The endoderm cells become the internal linings of organisms, such as the stomach, colon, small intestine, liver, and pancreas of the digestive system and the lungs. The mesoderm gives rise to other tissues not formed by the ectoderm, such as the heart, muscles, bones, blood, dermis of the skin, bone marrow, and the urogenital system. This germ layer is more specific for species, as it is the distinguishing layer of the three that can identify evolutionarily higher life-forms (e.g., bilateral organisms like humans) from lower-life forms (with radial symmetry). Lastly, the ectoderm is the outer layer of cells that become the epidermis and hair while being the precursor to the mammary glands, central nervous system , and the peripheral nervous systems . [ 21 ]
The figure above shows how the development of a pig , cow , rabbit , and human offspring are similar when compared to one another. This figure shows how the germ layers can become different organs and tissues in evolutionarily higher life-forms and how these species essentially develop very similarly. Additionally, it shows how multiple species develop in a parallel manner but branch off to develop more specific features for the organism such as hooves, a tail, or ears.
In developing vertebrate offspring, a neural tube is formed through either primary or secondary neurulation . Some species develop their spine and nervous system using both primary and secondary neurulation, while others use only primary or secondary neurulation. [ 22 ] In human fetal development, primary neurulation occurs during weeks 3 and 4 of gestation to develop the brain and spinal cord. Then during weeks 5 and 6 of gestation, secondary neurulation forms the lower sacral and coccygeal cord. [ 23 ]
The diagram to the right illustrates primary neurulation, which is the process of cells surrounding the neural plate interacting with neural plate cells to proliferate, converge, and pinch off to form a hollow tube above the notochord and mesoderm. This process is discontinuous and can start at different points along the cranial-caudal axis necessary for it to close. [ 23 ] After the neural crest closes, the neural crest cells and ectoderm cells separate and the ectoderm becomes the epidermis surrounding this complex. The neural crest cells differentiate to become components of most of the peripheral nervous system in animals. Next, the notochord degenerates to become only the nucleus pulposus of the intervertebral discs and the mesoderm cells differentiate to become the somites and skeletal muscle later on. Also during this stage, the neural crest cells become the spinal ganglions, which function as the brain in organisms like earthworms and arthropods . [ 24 ] In more advanced organisms like amphibians , birds and mammals ; [ 22 ] the spinal ganglions consists of a cluster of nerve bodies positioned along the spinal cord at the dorsal and ventral roots of a spinal nerve, which is a pair of nerves that correspond to a vertebra of the spine. [ 25 ]
In secondary neurulation, caudal and sacral regions of the spine are formed after primary neurulation is finished. This process initiates once primary neurulation is finished and the posterior neuropore closes, so the tail bud can proliferate and condense, then create a cavity and fuse with the central canal of the neural tube. Secondary neurulation occurs in the small region starting at the spinal tail bud up to the posterior neuropore, which is the open neural folds near the tail region that don't close through primary neurulation. As canalization progresses over the next few weeks, neurons and ependymal cells (cells that create cerebral spinal fluid [ 26 ] ) differentiate to become the tail end of the spinal cord. Next, the closed neural tube contains neuroepithelial cells that immediately divide after closure and a second type of cell forms; the neuroblast. Neuroblast cells form the mantle layer, which later becomes the gray matter , which then gives rise to a marginal layer that becomes the white matter of the spinal cord. [ 23 ] Secondary neurulation is seen in the neural tube of the lumbar and tail vertebrae of frogs and chicks and in both instances, this process is like a continuation of gastrulation. [ 22 ]
In most species, the young organism that is just born or hatched is not sexually mature yet and in most animals, this young organism looks quite different than the adult form. [ 20 ] This young organism is the larva and is the intermediate form before metamorphosing into an adult. [ 27 ] [ 8 ] A well known example of a larval form of an animal is the caterpillar of butterflies and moths . Caterpillars keep growing and feeding in order for enough energy during the pupal stage, when necessary body parts for metamorphosis are grown. [ 28 ] The juvenile phase is different in plants and animals, but in plants juvenility is an early phase of plant growth in which plants can't flower. [ 29 ] In animals, the juvenile stage is most commonly found in social mammals, such as wild dogs , monkeys , apes , lions , wolves , and more. In humans, puberty marks the end of this stage and adolescence follows. Some species begin puberty and reproduction before the juvenile stage is over, such as in female non-human primates. [ 30 ] The larval and pupal stages can be seen in the figure to the right.
The process of an organism's body undergoing structural and physical changes after birth or hatching to become suitable for its adult environment is metamorphosis . [ 31 ] For example, amphibian tadpoles have a maturation of liver enzymes, hemoglobin , and eye pigments, in addition to their nervous, digestive, and reproductive systems being remodeled. [ 32 ] In all species, molting and juvenile hormones appear to regulate these changes. [ 31 ] The figure to the right shows the stages of life in butterflies and their metamorphosis transforms the caterpillar into a butterfly.
Adulthood is the stage of when physical and intellectual maturity have been achieved and this differs between species. In humans , adulthood is thought to be around 20 or 21 years old and is the longest stage of life, but in all species it ends with death. [ 33 ] In dogs , small breeds (e.g., Yorkshire Terrier , Chihuahua , Cocker Spaniel , etc.) physically mature faster than large breeds (e.g., Saint Bernard , Great Dane , Golden Retriever , etc.), so adulthood is reached anywhere from 12 to 24 months or 1 to 2 years. [ 34 ] In contrast, many insect species have long larval stages and the adult stage is only for reproduction. The silkworm moths don't have mouthparts and don't feed, so they have to consume enough food during the larval stage for energy to survive and mate. [ 20 ]
Senescence is when cells stop dividing but don't die, but these cells can build up and cause problems in the body. These cells can release substances that cause inflammation and can damage healthy nearby cells. [ 35 ] Senescence can be induced by un-repaired DNA damage (e.g., from radiation, [ 36 ] old age, etc.) or other cellular stress [ 37 ] and also is the state of being old. [ 38 ]
Most organisms undergo allometric changes in shape as they grow and mature , while others engage in metamorphosis . Even reptiles (non-avian sauropsids, e.g., crocodilians , turtles , snakes , [ 39 ] and lizards [ 40 ] ), in which the offspring are often viewed as miniature adults, show a variety of ontogenetic changes in morphology and physiology . [ 41 ] | https://en.wikipedia.org/wiki/Ontogeny |
The theory of recapitulation , also called the biogenetic law or embryological parallelism —often expressed using Ernst Haeckel 's phrase " ontogeny recapitulates phylogeny "—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching ( ontogeny ), goes through stages resembling or representing successive adult stages in the evolution of the animal's remote ancestors ( phylogeny ). It was formulated in the 1820s by Étienne Serres based on the work of Johann Friedrich Meckel , after whom it is also known as the Meckel–Serres law .
Since embryos also evolve in different ways , the shortcomings of the theory had been recognized by the early 20th century, and it had been relegated to "biological mythology" [ 1 ] by the mid-20th century. [ 2 ]
Analogies to recapitulation theory have been formulated in other fields, including cognitive development [ 3 ] and music criticism .
The idea of recapitulation was first formulated in biology from the 1790s onwards by the German natural philosophers Johann Friedrich Meckel and Carl Friedrich Kielmeyer , and by Étienne Serres [ 4 ] after which, Marcel Danesi states, it soon gained the status of a supposed biogenetic law. [ 5 ]
The embryological theory was formalised by Serres in 1824–1826, based on Meckel's work, in what became known as the "Meckel-Serres Law". This attempted to link comparative embryology with a "pattern of unification" in the organic world. It was supported by Étienne Geoffroy Saint-Hilaire , and became a prominent part of his ideas. It suggested that past transformations of life could have been through environmental causes working on the embryo, rather than on the adult as in Lamarckism . These naturalistic ideas led to disagreements with Georges Cuvier . The theory was widely supported in the Edinburgh and London schools of higher anatomy around 1830, notably by Robert Edmond Grant , but was opposed by Karl Ernst von Baer 's ideas of divergence , and attacked by Richard Owen in the 1830s. [ 6 ]
Ernst Haeckel (1834–1919) attempted to synthesize the ideas of Lamarckism and Goethe 's Naturphilosophie with Charles Darwin 's concepts. While often seen as rejecting Darwin's theory of branching evolution for a more linear Lamarckian view of progressive evolution, this is not accurate: Haeckel used the Lamarckian picture to describe the ontogenetic and phylogenetic history of individual species, but agreed with Darwin about the branching of all species from one, or a few, original ancestors. [ 8 ] Since early in the twentieth century, Haeckel's "biogenetic law" has been refuted on many fronts. [ 9 ]
Haeckel formulated his theory as "Ontogeny recapitulates phylogeny". The notion later became simply known as the recapitulation theory. Ontogeny is the growth (size change) and development (structure change) of an individual organism; phylogeny is the evolutionary history of a species. Haeckel claimed that the development of advanced species passes through stages represented by adult organisms of more primitive species. [ 9 ] Otherwise put, each successive stage in the development of an individual represents one of the adult forms that appeared in its evolutionary history. [ citation needed ]
For example, Haeckel proposed that the pharyngeal grooves between the pharyngeal arches in the neck of the human embryo not only roughly resembled gill slits of fish, but directly represented an adult "fishlike" developmental stage, signifying a fishlike ancestor. Embryonic pharyngeal slits, which form in many animals when the thin branchial plates separating pharyngeal pouches and pharyngeal grooves perforate, open the pharynx to the outside. Pharyngeal arches appear in all tetrapod embryos: in mammals , the first pharyngeal arch develops into the lower jaw ( Meckel's cartilage ), the malleus and the stapes .
Haeckel produced several embryo drawings that often overemphasized similarities between embryos of related species. Modern biology rejects the literal and universal form of Haeckel's theory, such as its possible application to behavioural ontogeny, i.e. the psychomotor development of young animals and human children. [ 10 ]
Haeckel's theory and drawings were criticised by his contemporary, the anatomist Wilhelm His Sr. (1831–1904), who had developed a rival "causal-mechanical theory" of human embryonic development. [ 11 ] [ 12 ] His's work specifically criticised Haeckel's methodology, arguing that the shapes of embryos were caused most immediately by mechanical pressures resulting from local differences in growth. These differences were, in turn, caused by "heredity". He compared the shapes of embryonic structures to those of rubber tubes that could be slit and bent, illustrating these comparisons with accurate drawings. Stephen Jay Gould noted in his 1977 book Ontogeny and Phylogeny that His's attack on Haeckel's recapitulation theory was far more fundamental than that of any empirical critic, as it effectively stated that Haeckel's "biogenetic law" was irrelevant. [ 13 ] [ 14 ]
Darwin proposed that embryos resembled each other since they shared a common ancestor, which presumably had a similar embryo, but that development did not necessarily recapitulate phylogeny: he saw no reason to suppose that an embryo at any stage resembled an adult of any ancestor. Darwin supposed further that embryos were subject to less intense selection pressure than adults, and had therefore changed less. [ 15 ]
Modern evolutionary developmental biology (evo-devo) follows von Baer, rather than Darwin, in pointing to active evolution of embryonic development as a significant means of changing the morphology of adult bodies. Two of the key principles of evo-devo, namely that changes in the timing ( heterochrony ) and positioning ( heterotopy ) within the body of aspects of embryonic development would change the shape of a descendant's body compared to an ancestor's, were first formulated by Haeckel in the 1870s. These elements of his thinking about development have thus survived, whereas his theory of recapitulation has not. [ 16 ]
The Haeckelian form of recapitulation theory is considered defunct. [ 17 ] Embryos do undergo a period or phylotypic stage where their morphology is strongly shaped by their phylogenetic position, [ 18 ] rather than selective pressures, but that means only that they resemble other embryos at that stage, not ancestral adults as Haeckel had claimed. [ 19 ] The modern view is summarised by the University of California Museum of Paleontology :
Embryos do reflect the course of evolution, but that course is far more intricate and quirky than Haeckel claimed. Different parts of the same embryo can even evolve in different directions. As a result, the Biogenetic Law was abandoned, and its fall freed scientists to appreciate the full range of embryonic changes that evolution can produce—an appreciation that has yielded spectacular results in recent years as scientists have discovered some of the specific genes that control development . [ 20 ]
The idea that ontogeny recapitulates phylogeny has been applied to some other areas.
English philosopher Herbert Spencer was one of the most energetic proponents of evolutionary ideas to explain many phenomena. In 1861, five years before Haeckel first published on the subject, Spencer proposed a possible basis for a cultural recapitulation theory of education with the following claim: [ 21 ]
If there be an order in which the human race has mastered its various kinds of knowledge, there will arise in every child an aptitude to acquire these kinds of knowledge in the same order... Education is a repetition of civilization in little. [ 22 ]
G. Stanley Hall used Haeckel's theories as the basis for his theories of child development. His most influential work, "Adolescence: Its Psychology and Its Relations to Physiology, Anthropology, Sociology, Sex, Crime, Religion and Education" in 1904 [ 23 ] suggested that each individual's life course recapitulated humanity's evolution from "savagery" to "civilization". Though he has influenced later childhood development theories, Hall's conception is now generally considered racist. [ 24 ] Developmental psychologist Jean Piaget favored a weaker version of the formula, according to which ontogeny parallels phylogeny because the two are subject to similar external constraints. [ 25 ]
The Austrian pioneer of psychoanalysis , Sigmund Freud , also favored Haeckel's doctrine. He was trained as a biologist under the influence of recapitulation theory during its heyday, and retained a Lamarckian outlook with justification from the recapitulation theory. [ 26 ] Freud also distinguished between physical and mental recapitulation, in which the differences would become an essential argument for his theory of neuroses . [ 26 ]
In the late 20th century, studies of symbolism and learning in the field of cultural anthropology suggested that "both biological evolution and the stages in the child's cognitive development follow much the same progression of evolutionary stages as that suggested in the archaeological record". [ 27 ]
The musicologist Richard Taruskin in 2005 applied the phrase "ontogeny becomes phylogeny" to the process of creating and recasting music history, often to assert a perspective or argument. For example, the peculiar development of the works by modernist composer Arnold Schoenberg (here an "ontogeny") is generalized in many histories into a "phylogeny" – a historical development ("evolution") of Western music toward atonal styles of which Schoenberg is a representative. Such historiographies of the "collapse of traditional tonality" are faulted by music historians as asserting a rhetorical rather than historical point about tonality's "collapse". [ 28 ]
Taruskin also developed a variation of the motto into the pun "ontogeny recapitulates ontology" to refute the concept of " absolute music " advancing the socio-artistic theories of the musicologist Carl Dahlhaus . Ontology is the investigation of what exactly something is, and Taruskin asserts that an art object becomes that which society and succeeding generations made of it. For example, Johann Sebastian Bach 's St. John Passion , composed in the 1720s, was appropriated by the Nazi regime in the 1930s for propaganda . Taruskin claims the historical development of the St John Passion (its ontogeny) as a work with an anti-Semitic message does, in fact, inform the work's identity (its ontology), even though that was an unlikely concern of the composer. Music or even an abstract visual artwork can not be truly autonomous ("absolute") because it is defined by its historical and social reception. [ 28 ] | https://en.wikipedia.org/wiki/Ontogeny_recapitulates_phylogeny |
In computer science , information science and systems engineering , ontology engineering is a field which studies the methods and methodologies for building ontologies , which encompasses a representation, formal naming and definition of the categories, properties and relations between the concepts, data and entities of a given domain of interest. In a broader sense, this field also includes a knowledge construction of the domain using formal ontology representations such as OWL/RDF.
A large-scale representation of abstract concepts such as actions, time, physical objects and beliefs would be an example of ontological engineering. [ 2 ] Ontology engineering is one of the areas of applied ontology , and can be seen as an application of philosophical ontology . Core ideas and objectives of ontology engineering are also central in conceptual modeling .
Ontology engineering aims at making explicit the knowledge contained within software applications, and within enterprises and business procedures for a particular domain. Ontology engineering offers a direction towards solving the inter-operability problems brought about by semantic obstacles, i.e. the obstacles related to the definitions of business terms and software classes. Ontology engineering is a set of tasks related to the development of ontologies for a particular domain.
Automated processing of information not interpretable by software agents can be improved by adding rich semantics to the corresponding resources, such as video files. One of the approaches for the formal conceptualization of represented knowledge domains is the use of machine-interpretable ontologies, which provide structured data in, or based on, RDF , RDFS , and OWL . Ontology engineering is the design and creation of such ontologies, which can contain more than just the list of terms ( controlled vocabulary ); they contain terminological, assertional, and relational axioms to define concepts (classes), individuals, and roles (properties) ( TBox , ABox , and RBox, respectively). [ 4 ] Ontology engineering is a relatively new field of study concerning the ontology development process, the ontology life cycle, the methods and methodologies for building ontologies, [ 5 ] [ 6 ] and the tool suites and languages that support them.
A common way to provide the logical underpinning of ontologies is to formalize the axioms with description logics , which can then be translated to any serialization of RDF , such as RDF/XML or Turtle . Beyond the description logic axioms, ontologies might also contain SWRL rules. The concept definitions can be mapped to any kind of resource or resource segment in RDF , such as images, videos, and regions of interest , to annotate objects, persons, etc., and interlink them with related resources across knowledge bases , ontologies, and LOD datasets. This information, based on human experience and knowledge, is valuable for reasoners for the automated interpretation of sophisticated and ambiguous contents, such as the visual content of multimedia resources. [ 7 ] Application areas of ontology-based reasoning include, but are not limited to, information retrieval , automated scene interpretation, and knowledge discovery .
An ontology language is a formal language used to encode the ontology. There are a number of such languages for ontologies, both proprietary and standards-based:
Life sciences is flourishing with ontologies that biologists use to make sense of their experiments. [ 9 ] For inferring correct conclusions from experiments, ontologies have to be structured optimally against the knowledge base they represent. The structure of an ontology needs to be changed continuously so that it is an accurate representation of the underlying domain .
Recently, an automated method was introduced for engineering ontologies in life sciences such as Gene Ontology (GO), [ 10 ] one of the most successful and widely used biomedical ontology. [ 11 ] Based on information theory, it restructures ontologies so that the levels represent the desired specificity of the concepts. Similar information theoretic approaches have also been used for optimal partition of Gene Ontology. [ 12 ] Given the mathematical nature of such engineering algorithms , these optimizations can be automated to produce a principled and scalable architecture to restructure ontologies such as GO.
Open Biomedical Ontologies (OBO), a 2006 initiative of the U.S. National Center for Biomedical Ontology, provides a common 'foundry' for various ontology initiatives, amongst which are:
and more
This article incorporates public domain material from the National Institute of Standards and Technology | https://en.wikipedia.org/wiki/Ontology_engineering |
The Ontology for Biomedical Investigations ( OBI ) is an open-access , integrated ontology for the description of biological and clinical investigations. [ 1 ] OBI provides a model for the design of an investigation, the protocols and instrumentation used, the materials used, the data generated and the type of analysis performed on it. The project is being developed as part of the OBO Foundry and as such adheres to all the principles therein such as orthogonal coverage (i.e. clear delineation from other foundry member ontologies) and the use of a common formal language. In OBI the common formal language used is the Web Ontology Language (OWL). As of March 2008, a pre-release version of the ontology was made available at the project's SVN repository. [ 2 ]
The Ontology for Biomedical Investigations (OBI) addresses the need for controlled vocabularies to support integration and joint ("cross-omics") analysis of experimental data, a need originally identified in the transcriptomics domain by the FGED Society , which developed the MGED Ontology as an annotation resource for microarray data. Smith B, Ashburner M, Rosse C, Bard J, Bug W, Ceusters W, et al. (November 2007). "The OBO Foundry: coordinated evolution of ontologies to support biomedical data integration" . Nature Biotechnology . 25 (11): 1251– 5. doi : 10.1038/nbt1346 . PMC 2814061 . PMID 17989687 . OBI uses the basic formal ontology [ 3 ] upper-level ontology as a means of describing general entities that do not belong to a specific problem domain. As such, all OBI classes are a subclass of some BFO class.
The ontology has the scope of modeling all biomedical investigations and as such contains ontology terms for aspects such as:
Less 'concrete' aspects such as the role a given entity may play in a particular scenario (for example the role of a chemical compound in an experiment) and the function of an entity (for example the digestive function of the stomach to nutriate the body) are also covered in the ontology.
The MGED Ontology was originally identified in the transcriptomics domain by the FGED Society and was developed to address the needs of data integration. Following a mutual decision to collaborate, this effort later became a wider collaboration between groups such as FGED, PSI and MSI in response to the needs of areas such as transcriptomics, proteomics and metabolomics and the FuGO (Functional Genomics Investigation Ontology) [ 4 ] was created. This later became the OBI covering the wider scope of all biomedical investigations.
As an international, cross-domain initiative, the OBI consortium draws upon a pool of experts from a variety of fields, not limited to biology. The current list of OBI consortium members is available at the OBI consortium website. The consortium is made up of a coordinating committee which is a combination of two subgroups, the Community Representative (those representing a particular biomedical community) and the Core Developers (ontology developers who may or may not be members of any single community). Separate to the coordinating committee is the Developers Working Group which consists of developers within the communities collaborating in the development of OBI at the discretion of current OBI Consortium members. | https://en.wikipedia.org/wiki/Ontology_for_Biomedical_Investigations |
Ontophylogenesis merges the concepts of Ontogenesis and Phylogenesis to yield Darwinian theory at the cellular level. [ 1 ]
Described by its originator Jean-Jacques Kupiec as "the extension of natural selection, taking place inside the organism among the cell populations of which it is constituted. It ends with evolution and ontogenesis merging into a single phenomenon." [ 2 ]
Hierarchical analysis of ontogenetic time describing heterochrony and taxonomy of developmental stages is viewed as a segmentation of ontogenetic time depicting phylogenesis. [ 3 ] This permits the graphical depiction of time based evolutions of organs for a set of species, and is consistent with accepted theories of evolutionary biology . [ 4 ]
This zoology –related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Ontophylogenesis |
Onyx Pharmaceuticals Inc. has been a biopharmaceutical company headquartered in South San Francisco , California . The company developed and marketed medicines for the treatment of cancer. Onyx was founded in 1992 by Kevin J. Kinsella and Frank McCormick Ph.D., FRS. [ 1 ] McCormick served as the chief scientific officer until 1998, [ 1 ] while Kinsella was the firm's chairman . [ 2 ] In 2009, the company acquired Proteolix, Inc. , a private biotechnology company, for $276 million in cash plus additional milestone payments. [ 3 ] [ better source needed ] In January 2012, the company was named "the top biotechnology takeover target in 2012" through an industry survey. [ 4 ] Onyx president and chief executive officer (CEO) N. Anthony Coles had said that Onyx liked its prospects as an independent company and was focused on bringing new therapies to patients. [ 5 ] However, at the end of August 2013, Amgen announced it was acquiring Onyx in an agreed $10.4 billion deal. [ 6 ]
Initial funding for the formation of Onyx came from biotechnology firm Chiron Corporation (granted a 43% stake in the new company) and venture capital investors: Avalon Ventures , Institutional Venture Partners , J. H. Whitney & Company , and Kleiner Perkins Caufield & Byers . [ 2 ] McCormick had been working on cancer treatments at Chiron before he was selected as vice president of research at the newly formed company, leading the company's research program. [ 2 ] The acting president of the firm at its inception was Samuel D. Colella, a partner at Institutional Venture Partners (an original Onyx backer). [ 2 ]
Sorafenib , co-developed and co-marketed with Bayer and sold under the trade name Nexavar, is a drug approved in the United States for the treatment of advanced renal cell carcinoma (kidney cancer) in 2005, and for the treatment of inoperable hepatocellular carcinoma , the most common form of liver cancer, in 2007. [ 7 ] [ 8 ] Sorafenib has also been evaluated in other types of cancer, including those of the thyroid (as a treatment of last resort) and breast (in comparison to capecitabine ). [ 9 ] [ 10 ]
Carfilzomib (marketed under the trade name Kyprolis) was approved by the FDA on June 20, 2012, for use in patients with multiple myeloma who have received at least two prior therapies, including treatment with bortezomib and an immunomodulatory therapy, and have demonstrated disease progression on or within 60 days of completion of the last therapy. [ 11 ] [ 12 ] Carfilzomib is also being evaluated in other stages of multiple myeloma. The most commonly reported adverse reactions (incidence ≥ 30%) are fatigue, anemia, nausea, thrombocytopenia, dyspnea, diarrhea, and pyrexia. [ 12 ]
Regorafenib (marketed under the trade name Stivarga), is currently being studied as a potential treatment option in multiple tumor types. [ 13 ] On 27 September 2012, the FDA approved regorafenib for the treatment of patients with metastatic colorectal cancer (CRC) who have been previously treated with fluoropyrimidine-, oxaliplatin, and irinotecan-based chemotherapy, an anti-VEGF therapy, and, if KRAS wild-type, an anti-EGFR therapy. [ 14 ] On February 25, 2013, the FDA approved regorafenib in a second indication to treat patients with locally advanced, unresectable or metastatic gastrointestinal stromal tumor (GIST) who have been previously treated with imatinib mesylate and sunitinib malate. [ 15 ] Regorafenib is a compound developed by Bayer. The most common adverse reactions (>/=20%) are asthenia/fatigue, HFSR, diarrhea, decreased appetite/food intake, hypertension, mucositis, dysphonia, and infection, pain (not otherwise specified), decreased weight, gastrointestinal and abdominal pain, rash, fever, and nausea. [ 16 ] In 2011, Bayer entered into an agreement with Onyx under which Onyx will receive a 20 percent royalty on any future global net sales of regorafenib in oncology. Bayer and Onyx jointly promote Stivarga in the United States. [ 17 ]
In June 2013, Amgen Inc offered to buy the shares of Onyx Pharmaceuticals for $120 per share, sending the shares up by around 30% after the news was announced. [ 18 ] Onyx announced on June 30, 2013, that it rejected the unsolicited proposal from Amgen. The Onyx board has authorized its financial adviser to contact potential suitors. [ 19 ] The acquisition was formally announced on 25 August 2013. [ 6 ]
In July 2014 the company announced the phase III failure of a Sorafenib - Capecitabine combination trial. The drug combination failed to increase progression free survival of patients with advanced breast cancer. [ 20 ] | https://en.wikipedia.org/wiki/Onyx_Pharmaceuticals |
Oocyte selection is a procedure that is performed prior to in vitro fertilization , in order to use oocytes with maximal chances of resulting in pregnancy. In contrast, embryo selection takes place after fertilization.
Not all women can conceive naturally, leaving them with a need for technologies and research that can help them have children. Women who might not be able to have their kids naturally may have the option of in vitro fertilization. In vitro fertilization can be a series of treatments that involves the fertilization of a mature egg with a sperm in a laboratory. [ 1 ] Oocyte selection is a part the process for in vitro fertilization. [ 2 ] An Oocyte is an egg/ovum that is not fully mature or developed and has not been fertilized; Therefore an oocyte is an undeveloped ovum.
Selecting an oocyte for in vitro fertilization involves assessing the quality of the oocyte which is usually done by accessing the morphological features of the oocyte. The major parts of the oocyte that are accessed for quality in terms of morphological characteristics are the cumulus cells, zona pellucida, polar body, perivitelline space, and cytoplasm; These are the main parts of the oocyte and are usually assessed by conventional microscopy. [ 3 ] The size of an oocyte is another factor of the quality of the oocyte; Larger oocyte are usually more quality than smaller ones. [ 4 ] Chromosomal evaluation may be performed. Embryos from rescued in vitro-matured metaphase II (IVM-MII) oocytes show significantly higher fertilization rates and more blastomeres per embryo compared with those from arrested metaphase I (MI) oocytes (58.5% vs. 43.9% and 5.7 vs. 5.0, respectively). [ 5 ]
Also, morphological features of the oocyte that can be obtained by standard light or polarized light microscopy . However, there is no clear tendency in recent publications to a general increase in predictive value of morphological features. [ 6 ] Suggested techniques include zona pellucida imaging , which can detect differences in birefringence between eggs, which is a predictor of compaction , blastulation and pregnancy. [ 7 ]
Potentially, polar body biopsy may be used for molecular analysis, and can be used for preimplantation genetic screening . [ 8 ]
This article related to medical technology is a stub . You can help Wikipedia by expanding it .
This human reproduction article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Oocyte_selection |
Oogenesis ( / ˌ oʊ . ə ˈ dʒ ɛ n ɪ s ɪ s / ) or ovogenesis is the differentiation of the ovum (egg cell) into a cell competent to further develop when fertilized. [ 1 ] It is developed from the primary oocyte by maturation. Oogenesis is initiated before birth during embryonic development.
In mammals , the first part of oogenesis starts in the germinal epithelium , which gives rise to the development of ovarian follicles , the functional unit of the ovary .
Oogenesis consists of several sub-processes: oocytogenesis , ootidogenesis , and finally maturation to form an ovum (oogenesis proper). Folliculogenesis is a separate sub-process that accompanies and supports all three oogenetic sub-processes.
Oogonium —(Oocytogenesis)—> Primary Oocyte —(Meiosis I)—> First Polar body (Discarded afterward) + Secondary oocyte —(Meiosis II)—> Second Polar Body (Discarded afterward) + Ovum
Oocyte meiosis, important to all animal life cycles yet unlike all other instances of animal cell division, occurs completely without the aid of spindle -coordinating centrosomes . [ 2 ] [ 3 ]
The creation of oogonia traditionally does not belong to oogenesis proper, but, instead, to the common process of gametogenesis , which, in the female human, begins with the processes of folliculogenesis , oocytogenesis, and ootidogenesis . Oogonia enter meiosis during embryonic development, becoming oocytes. Meiosis begins with DNA replication and meiotic crossing over. It then stops in early prophase.
Mammalian oocytes are maintained in meiotic prophase arrest for a very long time—months in mice, years in humans. Initially, the arrest is due to lack of sufficient cell cycle proteins to allow meiotic progression. However, as the oocyte grows, these proteins are synthesized, and meiotic arrest becomes dependent on cyclic AMP . [ 4 ] The cyclic AMP is generated by the oocyte by adenylyl cyclase in the oocyte membrane. The adenylyl cyclase is kept active by a constitutively active G-protein-coupled receptor known as GPR3 and a G-protein, Gs, also present in the oocyte membrane. [ 5 ]
Maintenance of meiotic arrest also depends on the presence of a multilayered complex of cells, known as a follicle, that surrounds the oocyte. Removal of the oocyte from the follicle causes meiosis to progress in the oocyte. [ 6 ] The cells that comprise the follicle, known as granulosa cells, are connected to each other by proteins known as gap junctions, that allow small molecules to pass between the cells. The granulosa cells produce a small molecule, cyclic GMP , that diffuses into the oocyte through the gap junctions. In the oocyte, cyclic GMP prevents the breakdown of cyclic AMP by the phosphodiesterase PDE3, and thus maintains meiotic arrest. [ 7 ] The cyclic GMP is produced by the guanylyl cyclase NPR2. [ 8 ]
As follicles grow, they acquire receptors for luteinizing hormone, a pituitary hormone that reinitiates meiosis in the oocyte and causes ovulation of a fertilizable egg. Luteinizing hormone acts on receptors in the outer layers of granulosa cells of the follicle, causing a decrease in cyclic GMP in the granulosa cells. [ 4 ] Because the granulosa cells and oocyte are connected by gap junctions, cyclic GMP also decreases in the oocyte, causing meiosis to resume. [ 9 ] Meiosis then proceeds to second metaphase, where it pauses again until fertilization. Luteinizing hormone also stimulates gene expression leading to ovulation. [ 10 ]
Oogenesis starts with the process of developing primary oocytes, which occurs via the transformation of oogonia into primary oocytes, a process called oocytogenesis . [ 11 ] From one single oogonium, only one mature oocyte will rise, with 3 other cells called polar bodies. Oocytogenesis is complete either before or shortly after birth.
It is commonly believed that, when oocytogenesis is complete, no additional primary oocytes are created, in contrast to the male process of spermatogenesis, where gametocytes are continuously created. In other words, primary oocytes reach their maximum development at ~20 weeks of gestational age, when approximately seven million primary oocytes have been created; however, at birth, this number has already been reduced to approximately 1-2 million per ovary. At puberty, the number of oocytes decreases even more to reach about 60,000 to 80,000 per ovary, and only about 400-500 mature oocytes will be produced during a woman's life, the others will undergo atresia (degeneration). [ 12 ] Two publications have challenged the belief that a finite number of oocytes are set around the time of birth generation in adult mammalian ovaries by putative germ cells in bone marrow and peripheral blood. [ 13 ] [ 14 ] The renewal of ovarian follicles from germline stem cells (originating from bone marrow and peripheral blood) has been reported in the postnatal mouse ovary. In contrast, DNA clock measurements do not indicate ongoing oogenesis during human females' lifetimes. [ 15 ] Thus, further experiments are required to determine the true dynamics of small follicle formation.
The succeeding phase of ootidogenesis occurs when the primary oocyte develops into an ootid . This is achieved by the process of meiosis. In fact, a primary oocyte is, by its biological definition, a cell whose primary function is to divide by the process of meiosis. [ 16 ]
However, although this process begins at prenatal age, it stops at prophase I . In late fetal life, all oocytes, still primary oocytes, have halted at this stage of development, called the dictyate . After menarche , these cells then continue to develop, although only a few do so every menstrual cycle .
Meiosis I of ootidogenesis begins during embryonic development, but halts in the diplotene stage of prophase I until puberty. The mouse oocyte in the dictyate (prolonged diplotene) stage actively repairs DNA damage, whereas DNA repair is not detectable in the pre-dictyate ( leptotene , zygotene and pachytene ) stages of meiosis. [ 17 ] For those primary oocytes that continue to develop in each menstrual cycle, however, synapsis occurs and tetrads form, enabling chromosomal crossover to occur. As a result of meiosis I, the primary oocyte has now developed into the secondary oocyte .
Immediately after meiosis I, the haploid secondary oocyte initiates meiosis II . However, this process is also halted at the metaphase II stage until fertilization , if such should ever occur. If the egg is not fertilized, it is disintegrated and released ( menstruation ) and the secondary oocyte does not complete meiosis II (and does not become an ovum ). When meiosis II has completed, an ootid and another polar body have now been created. The polar body is small in size.
The ovarian cycle is divided into several phases:
The uterine cycle [ 20 ] occurs parallel to the ovarian cycle and is induced by estrogen and progesterone. The endometrium , formed by a monostratified cylindrical epithelium, with uterine glands (simple tubular), connective with a functional superficial layer (divided into a spongy layer, a compact layer, and a deeper basal layer, which is always maintained, presents four phases:
If, instead, there is fertilization, the uterine mucosa is modified to accommodate the fertilized egg, and the secretive phase is maintained.
Both polar bodies disintegrate at the end of Meiosis II, leaving only the ootid, which then eventually undergoes maturation into a mature ovum.
The function of forming polar bodies is to discard the extra haploid sets of chromosomes that have resulted as a consequence of meiosis.
In vitro maturation ( IVM ) is the technique of letting ovarian follicles mature in vitro . It can potentially be performed before an IVF . In such cases, ovarian hyperstimulation is not essential. Rather, oocytes can mature outside the body prior to IVF. Hence, no (or at least a lower dose of) gonadotropins have to be injected in the body. [ 21 ] Immature eggs have been grown until maturation in vitro at a 10% survival rate, but the technique is not yet clinically available. [ 22 ] With this technique, cryopreserved ovarian tissue could possibly be used to make oocytes that can directly undergo in vitro fertilization . [ 22 ]
By definition, it means to recapitulate mammalian oogenesis and produce fertilizable oocytes in vitro. It is a complex process involving several different cell types, precise follicular cell-oocyte reciprocal interactions, a variety of nutrients and combinations of cytokines, and precise growth factors and hormones depending on the developmental stage. [ 23 ] In 2016, two papers published by Morohaku et al. and Hikabe et al. reported in vitro procedures that appear to reproduce efficiently these conditions allowing for the production, completely in a dish, of a relatively large number of oocytes that are fertilizable and capable of giving rise to viable offspring in the mouse. This technique can be mainly benefited in cancer patients where in today's condition their ovarian tissue
is cryopreserved for preservation of fertility. Alternatively to the autologous transplantation, the development of culture systems that support oocyte development from the primordial follicle stage represent a valid strategy to restore fertility. Over time, many studies have been conducted with the aim to optimize the characteristics of ovarian tissue culture systems and to better support the three main phases: 1) activation of primordial follicles; 2) isolation and culture of growing preantral follicles; 3) removal from the follicle environment and maturation of oocyte cumulus complexes. While complete oocyte in vitro development has been achieved in mouse, with the production of live offspring, the goal of obtaining oocytes of sufficient quality to support embryo development has not been completely reached into higher mammals despite decades of effort. [ 24 ]
BRCA1 and ATM proteins are employed in repair of DNA double-strand break during meiosis . These proteins appear to have a critical role in resisting ovarian aging . [ 25 ] However, homologous recombinational repair of DNA double-strand breaks mediated by BRCA1 and ATM weakens with age in oocytes of humans and other species. [ 25 ] Women with BRCA1 mutations have lower ovarian reserves and experience earlier menopause than women without these mutations. Even in woman without specific BRCA1 mutations, ovarian aging is associated with depletion of ovarian reserves leading to menopause, but at a slower rate than in those with such mutations. Since older premenopausal women ordinarily have normal progeny, their capability for meiotic recombinational repair appears to be sufficient to prevent deterioration of their germline despite the reduction in ovarian reserve. DNA damages may arise in the germline during the decades long period in humans between early oocytogenesis and the stage of meiosis in which homologous chromosomes are effectively paired ( dictyate stage). It has been suggested that such DNA damages may be removed, in large part, by mechanisms dependent on chromosome pairing, such as homologous recombination. [ 26 ]
Some algae and the oomycetes produce eggs in oogonia . In the brown alga Fucus , all four egg cells survive oogenesis, which is an exception to the rule that generally only one product of female meiosis survives to maturity.
In plants , oogenesis occurs inside the female gametophyte via mitosis . In many plants such as bryophytes , ferns , and gymnosperms , egg cells are formed in archegonia . In flowering plants , the female gametophyte has been reduced to an eight-celled embryo sac within the ovule inside the ovary of the flower. Oogenesis occurs within the embryo sac and leads to the formation of a single egg cell per ovule.
In ascaris , the oocyte does not even begin meiosis until the sperm touches it, in contrast to mammals, where meiosis is completed in the estrus cycle.
In female Drosophila flies, genetic recombination occurs during meiosis . This recombination is associated with formation of DNA double-strand breaks and the repair of these breaks. [ 27 ] The repair process leads to crossover recombinants as well as at least three times as many noncrossover recombinants (e.g. arising by gene conversion without crossover). [ 27 ]
Cho WK, Stern S, Biggers JD. 1974. Inhibitory effect of dibutyryl cAMP on mouse oocyte maturation in vitro. J Exp Zool.187:383-386 | https://en.wikipedia.org/wiki/Oogenesis |
Oophagy ( / oʊ ˈ ɒ f ə dʒ i / oh- OFF -ə-jee ) or ovophagy , literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus . [ 1 ] The word oophagy is formed from the classical Greek ᾠόν ( ōion , "egg") and classical Greek φᾱγεῖν ( phāgein , "to eat"). In contrast, adelphophagy is the cannibalism of a multi-celled embryo. [ 1 ]
Oophagy is thought to occur in all sharks in the order Lamniformes and has been recorded in the bigeye thresher ( Alopias superciliosus ), the pelagic thresher ( A. pelagicus ), the shortfin mako ( Isurus oxyrinchus ) and the porbeagle ( Lamna nasus ) among others. [ 1 ] It also occurs in the tawny nurse shark ( Nebrius ferrugineus ), and in the family Pseudotriakidae .
This practice may lead to larger embryos or prepare the embryo for a predatory lifestyle. [ 2 ]
There are variations in the extent of oophagy among the different shark species. The grey nurse shark ( Carcharias taurus ) practices intrauterine cannibalism, the first developed embryo consuming both additional eggs and any other developing embryos. Slender smooth-hounds ( Gollum attenuatus ), form egg capsules which contain 30-80 ova, within which only one ovum develops; the remaining ova are ingested and their yolks stored in its external yolk sac. The embryo then proceeds to develop normally, without ingesting further eggs. [ 1 ]
Oophagy is used as a synonym of the egg predation practised by some snakes and other animals.
Oophagy is used to describe the destruction of non-queen eggs in nests of eusocial insects , especially the social wasps , bees, and ants. This is seen in the wasp species Polistes biglumis and Polistes humilis . [ 3 ] Oophagy has been observed in the ant Leptothorax acervorum [ 4 ] and the wasp Parachartergus fraternus , where oophagy is practiced to increase energy circulation and provide more dietary protein. [ 5 ] The social wasp Polistes fuscatus use oophagy as a method to establish a dominance hierarchy ; dominant females eat the eggs of subordinate females such that they no longer produce eggs, possibly due to the unnecessary expenditure of energy and resources. [ 6 ] This behavior has also been observed in some bee species. Such bee species include Xylocopa sulcatipes [ 7 ] and Bombus ruderatus , where queen bees will eat larvae deposited by workers or eject them from the nest in order to maintain dominance over the colony. [ 8 ] | https://en.wikipedia.org/wiki/Oophagy |
An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae , fungi , and oomycetes . [ 1 ] They are believed to have evolved either through the fusion of two species or the chemically induced stimulation of mycelia , leading to oospore formation. [ 2 ]
In Oomycetes , oospores can also result from asexual reproduction, by apomixis . These haploid, non-motile spores are the site of meiosis and karyogamy in oomycetes. [ 3 ]
A dormant oospore, when observed under an electron microscope, has led researchers to draw conclusion that there is only a single central globule with other storage bodies surrounding it. [ 4 ] | https://en.wikipedia.org/wiki/Oospore |
An opacifier is a substance added to a material in order to make the ensuing system opaque . An example of a chemical opacifier is titanium dioxide (TiO 2 ), which is used as an opacifier in paints, in paper, and in plastics. It has very high refraction index (rutile modification 2.7 and anatase modification 2.55) and optimum refraction is obtained with crystals about 225 nanometers. Impurities in the crystal alter the optical properties. [ 1 ] It is also used to opacify ceramic glazes [ 2 ] and milk glass ; bone ash is also used.
Opacifiers must have a refractive index (RI) substantially different from the system. Conversely, clarity may be achieved in a system by choosing components with very similar refractive indices. [ 3 ]
Ancient milk glasses used crystals of calcium antimonate , formed in the melt from calcium present in the glass and an antimony additive. Opaque yellow glasses contained crystals of lead antimonate ; bindheimite mineral may have been used as the additive. Under oxidizing condition, lead also forms incompletely dissolved lead pyroantimonate (Pb 2 Sb 2 O 7 ). From 2nd century BC tin oxide appears in use as opacifier, likely in the form of cassiterite mineral. Opaque yellow can be produced as lead stannate ; the color is paler than the lead antimonate one. Later calcium and sodium phosphates became used; bone ash contains calcium phosphate in a high proportion. Calcium fluoride was also used, especially in China. [ 4 ]
For dental ceramics, several approaches are in use. Spodumene or mica crystals can be precipitated. Fluorides of aluminium, calcium, barium, and magnesium can be used with suitable heat treatment. Tin oxide can be used, but zirconia and titania give better results; for titania, the appropriate resulting particle size is between submicron to 20 μm. Another desirable opacifier is zinc oxide . [ 5 ]
Opacifiers must also form small particles in the system. Opacifiers are generally inert .
In context of x-rays, opacifiers are additives with high absorption of x-rays; typically these are particles or compounds of lead, barium (often barium sulfate ), tungsten, or other high atomic weight elements. Sometimes opacifiers are added to medical implants to make them visible under X-ray imaging. This is especially true in the case of most polymers which are often unrecognizable in the body when viewed using X-rays.
In solid rocket propellants and some translucent smokeless powders , the primary method of heat transfer into the propellant grain from the combustion process is by radiation, and opacifiers such as " lamp black " may be added to the propellant mixture to ensure the heat does not penetrate far below the surface of the grain, which could cause detonation. The opacifiers also prevent sub-surface overheating and localized premature ignition in the grains where imperfections absorbing the thermal radiation are present. Carbon black is commonly used for this purpose; other possible additives are nigrosin , Prussian blue , methylene blue , etc. in amounts ranging commonly between 0.1 and 0.5%. [ 6 ] | https://en.wikipedia.org/wiki/Opacifier |
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation , especially visible light . In radiative transfer , it describes the absorption and scattering of radiation in a medium , such as a plasma , dielectric , shielding material , glass, etc. An opaque object is neither transparent (allowing all light to pass through) nor translucent (allowing some light to pass through). When light strikes an interface between two substances, in general, some may be reflected, some absorbed, some scattered, and the rest transmitted (also see refraction ). Reflection can be diffuse , for example light reflecting off a white wall, or specular , for example light reflecting off a mirror. An opaque substance transmits no light, and therefore reflects, scatters, or absorbs all of it. Other categories of visual appearance, related to the perception of regular or diffuse reflection and transmission of light, have been organized under the concept of cesia in an order system with three variables, including opacity, transparency and translucency among the involved aspects. Both mirrors and carbon black are opaque. Opacity depends on the frequency of the light being considered. For instance, some kinds of glass , while transparent in the visual range , are largely opaque to ultraviolet light. More extreme frequency-dependence is visible in the absorption lines of cold gases . Opacity can be quantified in many ways (see: Mathematical descriptions of opacity ) .
Different processes can lead to opacity, including absorption , reflection , and scattering .
Late Middle English opake, from Latin opacus 'darkened'. The current spelling (rare before the 19th century) has been influenced by the French form.
Radiopacity is preferentially used to describe opacity of X-rays . In modern medicine, radiodense substances are those that will not allow X-rays or similar radiation to pass. Radiographic imaging has been revolutionized by radiodense contrast media , which can be passed through the bloodstream, the gastrointestinal tract , or into the cerebral spinal fluid and utilized to highlight CT scan or X-ray images. Radiopacity is one of the key considerations in the design of various devices such as guidewires or stents that are used during radiological intervention. The radiopacity of a given endovascular device is important since it allows the device to be tracked during the interventional procedure.
The words "opacity" and "opaque" are often used as colloquial terms for objects or media with the properties described above. However, there is also a specific, quantitative definition of "opacity", used in astronomy, plasma physics, and other fields, given here.
In this use, "opacity" is another term for the mass attenuation coefficient (or, depending on context, mass absorption coefficient , the difference is described here ) κ ν {\displaystyle \kappa _{\nu }} at a particular frequency ν {\displaystyle \nu } of electromagnetic radiation.
More specifically, if a beam of light with frequency ν {\displaystyle \nu } travels through a medium with opacity κ ν {\displaystyle \kappa _{\nu }} and mass density ρ {\displaystyle \rho } , both constant, then the intensity will be reduced with distance x according to the formula I ( x ) = I 0 e − κ ν ρ x {\displaystyle I(x)=I_{0}e^{-\kappa _{\nu }\rho x}} where
For a given medium at a given frequency, the opacity has a numerical value that may range between 0 and infinity, with units of length 2 /mass.
Opacity in air pollution work refers to the percentage of light blocked instead of the attenuation coefficient (aka extinction coefficient) and varies from 0% light blocked to 100% light blocked:
Opacity = 100 % ( 1 − I ( x ) I 0 ) {\displaystyle {\text{Opacity}}=100\%\left(1-{\frac {I(x)}{I_{0}}}\right)}
It is customary to define the average opacity, calculated using a certain weighting scheme. Planck opacity (also known as Planck-Mean-Absorption-Coefficient [ 1 ] ) uses the normalized Planck black-body radiation energy density distribution , B ν ( T ) {\displaystyle B_{\nu }(T)} , as the weighting function, and averages κ ν {\displaystyle \kappa _{\nu }} directly: κ P l = ∫ 0 ∞ κ ν B ν ( T ) d ν ∫ 0 ∞ B ν ( T ) d ν = ( π σ T 4 ) ∫ 0 ∞ κ ν B ν ( T ) d ν , {\displaystyle \kappa _{Pl}={\int _{0}^{\infty }\kappa _{\nu }B_{\nu }(T)d\nu \over \int _{0}^{\infty }B_{\nu }(T)d\nu }=\left({\pi \over \sigma T^{4}}\right)\int _{0}^{\infty }\kappa _{\nu }B_{\nu }(T)d\nu ,} where σ {\displaystyle \sigma } is the Stefan–Boltzmann constant .
Rosseland opacity (after Svein Rosseland ), on the other hand, uses a temperature derivative of the Planck distribution , u ( ν , T ) = ∂ B ν ( T ) / ∂ T {\displaystyle u(\nu ,T)=\partial B_{\nu }(T)/\partial T} , as the weighting function, and averages κ ν − 1 {\displaystyle \kappa _{\nu }^{-1}} , 1 κ = ∫ 0 ∞ κ ν − 1 u ( ν , T ) d ν ∫ 0 ∞ u ( ν , T ) d ν . {\displaystyle {\frac {1}{\kappa }}={\frac {\int _{0}^{\infty }\kappa _{\nu }^{-1}u(\nu ,T)d\nu }{\int _{0}^{\infty }u(\nu ,T)d\nu }}.} The photon mean free path is λ ν = ( κ ν ρ ) − 1 {\displaystyle \lambda _{\nu }=(\kappa _{\nu }\rho )^{-1}} . The Rosseland opacity is derived in the diffusion approximation to the radiative transport equation. It is valid whenever the radiation field is isotropic over distances comparable to or less than a radiation mean free path, such as in local thermal equilibrium. In practice, the mean opacity for Thomson electron scattering is: κ e s = 0.20 ( 1 + X ) c m 2 g − 1 {\displaystyle \kappa _{\rm {es}}=0.20(1+X)\,\mathrm {cm^{2}\,g^{-1}} } where X {\displaystyle X} is the hydrogen mass fraction. For nonrelativistic thermal bremsstrahlung , or free-free transitions, assuming solar metallicity , it is: [ 2 ] κ f f ( ρ , T ) = 0.64 × 10 23 ( ρ [ g c m − 3 ] ) ( T [ K ] ) − 7 / 2 c m 2 g − 1 . {\displaystyle \kappa _{\rm {ff}}(\rho ,T)=0.64\times 10^{23}(\rho [{\rm {g}}~{\rm {\,cm}}^{-3}])(T[{\rm {K}}])^{-7/2}{\rm {\,cm}}^{2}{\rm {\,g}}^{-1}.} The Rosseland mean attenuation coefficient is: [ 3 ] 1 κ = ∫ 0 ∞ ( κ ν , e s + κ ν , f f ) − 1 u ( ν , T ) d ν ∫ 0 ∞ u ( ν , T ) d ν . {\displaystyle {\frac {1}{\kappa }}={\frac {\int _{0}^{\infty }(\kappa _{\nu ,{\rm {es}}}+\kappa _{\nu ,{\rm {ff}}})^{-1}u(\nu ,T)d\nu }{\int _{0}^{\infty }u(\nu ,T)d\nu }}.} | https://en.wikipedia.org/wiki/Opacity |
Opal is a hydrated amorphous form of silica (SiO 2 · n H 2 O); its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous (chemical) physical structure, it is classified as a mineraloid , unlike crystalline forms of silica, which are considered minerals . It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock , being most commonly found with limonite , sandstone , rhyolite , marl , and basalt .
The name opal is believed to be derived from the Sanskrit word upala ( उपल ), which means 'jewel', and later the Greek derivative opállios ( ὀπάλλιος ). [ 5 ]
There are two broad classes of opal: precious and common. Precious opal displays play-of-color ( iridescence ); common opal does not. [ 6 ] Play-of-color is defined as "a pseudo chromatic optical effect resulting in flashes of colored light from certain minerals, as they are turned in white light." [ 7 ] The internal structure of precious opal causes it to diffract light, resulting in play-of-color. Depending on the conditions in which it formed, opal may be transparent, translucent, or opaque, and the background color may be white, black, or nearly any color of the visual spectrum. Black opal is considered the rarest, while white, gray, and green opals are the most common.
Precious opal shows a variable interplay of internal colors, and though it is a mineraloid, it has an internal structure. At microscopic scales, precious opal is composed of silica spheres some 150–300 nm (5.9 × 10 −6 –1.18 × 10 −5 in) in diameter in a hexagonal or cubic close-packed lattice . It was shown by J. V. Sanders in the mid-1960s [ 8 ] [ 9 ] that these ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal. [ 10 ] The regularity of the sizes and the packing of these spheres is a prime determinant of the quality of precious opal. Where the distance between the regularly packed planes of spheres is around half the wavelength of a component of visible light , the light of that wavelength may be subject to diffraction from the grating created by the stacked planes. The colors that are observed are determined by the spacing between the planes and the orientation of planes with respect to the incident light. The process can be described by Bragg's law of diffraction.
Visible light cannot pass through large thicknesses of the opal. This is the basis of the optical band gap in a photonic crystal . [ 11 ] In addition, microfractures may be filled with secondary silica and form thin lamellae inside the opal during its formation. The term opalescence is commonly used to describe this unique and beautiful phenomenon, which in gemology is termed play of color . In gemology, opalescence is applied to the hazy-milky- turbid sheen of common or potch opal which does not show a play of color. [ clarification needed ] Opalescence is a form of adularescence .
For gemstone use, most opal is cut and polished to form a cabochon . "Natural" opal refers to polished stones consisting wholly of precious opal. Opals too thin to produce a "natural" opal may be combined with other materials to form "composite" gems. An opal doublet consists of a relatively thin layer of precious opal, backed by a layer of dark-colored material, most commonly ironstone, dark or black common opal (potch), onyx, or obsidian. The darker backing emphasizes the play of color and results in a more attractive display than a lighter potch. An opal triplet is similar to a doublet but has a third layer, a domed cap of clear quartz or plastic on the top. The cap takes a high polish and acts as a protective layer for the opal. The top layer also acts as a magnifier, to emphasize the play of color of the opal beneath, which is often an inferior specimen or an extremely thin section of precious opal. Triplet opals tend to have a more artificial appearance and are not classed as precious gemstones, but rather "composite" gemstones. Jewelry applications of precious opal can be somewhat limited by opal's sensitivity to heat due primarily to its relatively high water content and predisposition to scratching. [ 12 ] Combined with modern techniques of polishing, a doublet opal can produce a similar effect to Natural black or boulder opal at a fraction of the price. Doublet opal also has the added benefit of having genuine opal as the top visible and touchable layer, unlike triplet opals.
Besides the gemstone varieties that show a play of color, the other kinds of common opal include the milk opal, milky bluish to greenish (which can sometimes be of gemstone quality); resin opal, which is honey-yellow with a resinous luster; wood opal, which is caused by the replacement of the organic material in wood with opal; [ 13 ] menilite , which is brown or grey; hyalite , a colorless glass-clear opal sometimes called Muller's glass; geyserite , also called siliceous sinter , deposited around hot springs or geysers ; and diatomaceous earth , the accumulations of diatom shells or tests. Common opal often displays a hazy-milky- turbid sheen from within the stone. In gemology , this optical effect is strictly defined as opalescence which is a form of adularescence.
"Girasol opal" is a term sometimes mistakenly and improperly used to refer to fire opals, as well as a type of transparent to semitransparent type milky quartz from Madagascar which displays an asterism, or star effect when cut properly. However, the true girasol opal [ 15 ] is a type of hyalite opal that exhibits a bluish glow or sheen that follows the light source around. It is not a play of color as seen in precious opal, but rather an effect from microscopic inclusions. It is also sometimes referred to as water opal, too, when it is from Mexico. The two most notable locations of this type of opal are Oregon and Mexico. [ 16 ]
A Peruvian opal (also called blue opal) is a semi-opaque to opaque blue-green stone found in Peru, which is often cut to include the matrix in the more opaque stones. It does not display a play of color. Blue opal also comes from Oregon and Idaho in the Owyhee region, as well as from Nevada around the Virgin Valley . [ 17 ]
Opal is also formed by diatoms . Diatoms are a form of algae that, when they die, often form layers at the bottoms of lakes, bays, or oceans. Their cell walls are made up of hydrated silicon dioxide which gives them structural coloration and therefore the appearance of tiny opals when viewed under a microscope. These cell walls or "tests" form the “grains” for the diatomaceous earth . This sedimentary rock is white, opaque, and chalky in texture. [ 18 ] Diatomite has multiple industrial uses such as filtering or adsorbing since it has a fine particle size and very porous nature, and gardening to increase water absorption.
Opal was rare and very valuable in antiquity. In Europe, it was a gem prized by royalty. [ 19 ] [ 20 ] Until the opening of vast deposits in Australia in the 19th century the only known source was Červenica beyond the Roman frontier in Slovakia . [ 21 ] Opal is the national gemstone of Australia. [ 22 ]
The primary sources of opal are Australia and Ethiopia, but because of inconsistent and widely varying accountings of their respective levels of extraction, it is difficult to accurately state what proportion of the global supply of opal comes from either country.
Australian opal has been cited as accounting for 95–97% of the world's supply of precious opal, [ 24 ] [ 25 ] with the state of South Australia accounting for 80% of the world's supply. [ 26 ] In 2012, Ethiopian opal production was estimated to be 14,000 kg (31,000 lb) by the United States Geological Survey. [ 27 ] USGS data from the same period (2012), reveals Australian opal production to be $41 million. [ 28 ] Because of the units of measurement, it is not possible to directly compare Australian and Ethiopian opal production, but these data and others suggest that the traditional percentages given for Australian opal production may be overstated. [ 29 ] Yet, the validity of data in the USGS report appears to conflict with that of Laurs et al. [ citation needed ] and Mesfin, [ citation needed ] who estimated the 2012 Ethiopian opal output (from Wegeltena ) to be only 750 kg (1,650 lb).
The town of Coober Pedy in South Australia is a major source of opal. The world's largest and most valuable gem opal " Olympic Australis " was found in August 1956 at the "Eight Mile" opal field in Coober Pedy. It weighs 17,000 carats (3.4 kg; 7.5 lb) and is 11 inches (280 mm) long, with a height of 4 + 3 ⁄ 4 in (120 mm) and a width of 4 + 1 ⁄ 2 in (110 mm). [ 30 ]
The Mintabie Opal Field in South Australia located about 250 km (160 mi) northwest of Coober Pedy has also produced large quantities of crystal opal and the rarer black opal. Over the years, it has been sold overseas incorrectly as Coober Pedy opal. The black opal is said to be some of the best examples found in Australia.
Andamooka in South Australia is also a major producer of matrix opal, crystal opal, and black opal. Another Australian town, Lightning Ridge in New South Wales , is the main source of black opal, opal containing a predominantly dark background (dark gray to blue-black displaying the play of color), collected from the Griman Creek Formation . [ 31 ] Boulder opal consists of concretions and fracture fillings in a dark siliceous ironstone matrix. It is found sporadically in western Queensland, from Kynuna in the north, to Yowah and Koroit in the south. [ 32 ] Its largest quantities are found around Jundah and Quilpie in South West Queensland . Australia also has opalized fossil remains, including dinosaur bones in New South Wales [ 33 ] and South Australia, [ 34 ] and marine creatures in South Australia. [ 35 ]
It has been reported that Northern African opal was used to make tools as early as 4000 BC. [ citation needed ] The first published report of gem opal from Ethiopia appeared in 1994, with the discovery of precious opal in the Menz Gishe District, North Shewa Province. [ 36 ] The opal, found mostly in the form of nodules, was of volcanic origin and was found predominantly within weathered layers of rhyolite . [ 37 ] This Shewa Province opal was mostly dark brown in color and had a tendency to crack. These qualities made it unpopular in the gem trade. In 2008, a new opal deposit was found approximately 180 km north of Shewa Province, near the town of Wegeltena , in Ethiopia's Wollo Province . The Wollo Province opal was different from the previous Ethiopian opal finds in that it more closely resembled the sedimentary opals of Australia and Brazil, with a light background and often vivid play-of-color. [ 38 ] Wollo Province opal, more commonly referred to as "Welo" or "Wello" opal, has become the dominant Ethiopian opal in the gem trade. [ 39 ]
The Virgin Valley [ 40 ] opal fields of Humboldt County in northern Nevada produce a wide variety of precious black, crystal, white, fire, and lemon opal. The black fire opal is the official gemstone of Nevada. Most of the precious opal is partial wood replacement. The precious opal is hosted and found in situ within a subsurface horizon or zone of bentonite , which is considered a "lode" deposit. Opals which have weathered out of the in situ deposits are alluvial and considered placer deposits . Miocene -age opalised teeth, bones, fish, and a snake head have been found. Some of the opal has high water content and may desiccate and crack when dried. The largest producing mines of Virgin Valley have been the famous Rainbow Ridge, [ 41 ] Royal Peacock, [ 42 ] Bonanza, [ 43 ] Opal Queen, [ 44 ] and WRT Stonetree/Black Beauty [ 45 ] mines. The largest unpolished black opal in the Smithsonian Institution, known as the "Roebling opal", [ 46 ] came out of the tunneled portion of the Rainbow Ridge Mine in 1917, and weighs 2,585 carats (517.0 g; 18.24 oz). The largest polished black opal in the Smithsonian Institution comes from the Royal Peacock opal mine in the Virgin Valley, weighing 160 carats (32 g; 1.1 oz), known as the "Black Peacock". [ 47 ]
Fire opal is a transparent to translucent opal with warm body colors of yellow to orange to red. Although fire opals don't usually show any play of color, they occasionally exhibit bright green flashes. The most famous source of fire opals is the state of Querétaro in Mexico; these opals are commonly called Mexican fire opals. [ 48 ] Fire opals that do not show a play of color are sometimes referred to as jelly opals. Mexican opals are sometimes cut in their rhyolitic host material if it is hard enough to allow cutting and polishing. This type of Mexican opal is referred to as a Cantera opal. Another type of opal from Mexico, referred to as Mexican water opal, is a colorless opal that exhibits either a bluish or golden internal sheen. [ 15 ]
Opal occurs in significant quantity and variety in central Mexico, where mining and production first originated in the state of Querétaro . In this region the opal deposits are located mainly in the mountain ranges of three municipalities: Colón , Tequisquiapan , and Ezequiel Montes . During the 1960s through to the mid-1970s, the Querétaro mines were heavily mined. Today's opal miners report that it was much easier to find quality opals with a lot of fire and play of color back then, whereas today the gem-quality opals are very hard to come by and command hundreds of US dollars or more. The orange-red background color is characteristic of all "fire opals," including "Mexican fire opal".
The oldest mine in Querétaro is Santa Maria del Iris. This mine was opened around 1870 and has been reopened at least 28 times since. At the moment there are about 100 mines in the regions around Querétaro, but most of them are now closed. The best quality of opals came from the mine Santa Maria del Iris, followed by La Hacienda la Esperanza, Fuentezuelas, La Carbonera, and La Trinidad. Important deposits in the state of Jalisco were not discovered until the late 1950s.
In 1957, Alfonso Ramirez (of Querétaro) accidentally discovered the first opal mine in Jalisco: La Unica, located on the outer area of the volcano of Tequila, near the Huitzicilapan farm in Magdalena . By 1960 there were around 500 known opal mines in this region alone. Other regions of the country that also produce opals (of lesser quality) are Guerrero , which produces an opaque opal similar to the opals from Australia (some of these opals are carefully treated with heat to improve their colors so high-quality opals from this area may be suspect). There are also some small opal mines in Morelos , Durango , Chihuahua , Baja California , Guanajuato , Puebla , Michoacán , and Estado de México .
Another source of white base opal or creamy opal in the United States is Spencer, Idaho . [ 49 ] A high percentage of the opal found there occurs in thin layers.
Other significant deposits of precious opal around the world can be found in the Czech Republic, Canada, Slovakia, Hungary, Turkey, Indonesia, Brazil (in Pedro II, Piauí [ 50 ] ), Honduras (more precisely in Erandique ), Guatemala, and Nicaragua.
In late 2008, NASA announced the discovery of opal deposits on Mars . [ 51 ]
Wood opal , also known as xylopal , [ 52 ] [ 53 ] is a form of opal, [ 54 ] as well as a type of petrified wood which has developed an opalescent sheen or, more rarely, where the wood has been completely replaced by opal.
Other names for this opalized sheen-like wood are opalized wood and opalized petrified wood . It is often used as a gemstone . [ 55 ]
Opals of all varieties have been synthesized experimentally and commercially. The discovery of the ordered sphere structure of precious opal led to its synthesis by Pierre Gilson in 1974. [ 10 ] The resulting material is distinguishable from natural opal by its regularity; under magnification, the patches of color are seen to be arranged in a "lizard skin" or "chicken wire" pattern. Furthermore, synthetic opals do not fluoresce under ultraviolet light. Synthetics are also generally lower in density and are often highly porous.
Opals which have been created in a laboratory are often termed "lab-created opals", which, while classifiable as man-made and synthetic, are very different from their resin-based counterparts which are also considered man-made and synthetic. The term "synthetic" implies that a stone has been created to be chemically and structurally indistinguishable from a genuine one, and genuine opal contains no resins or polymers. The finest modern lab-created opals do not exhibit the lizard skin or columnar patterning of earlier lab-created varieties, and their patterns are non-directional. They can still be distinguished from genuine opals, however, by their lack of inclusions and the absence of any surrounding non-opal matrix . While many genuine opals are cut and polished without a matrix, the presence of irregularities in their play-of-color continues to mark them as distinct from even the best lab-created synthetics.
Other research in macroporous structures have yielded highly ordered materials that have similar optical properties to opals and have been used in cosmetics. [ 56 ] Synthetic opals are also deeply investigated in photonics for sensing and light management purposes. [ 57 ] [ 58 ]
The lattice of spheres of opal that cause interference with light is several hundred times larger than the fundamental structure of crystalline silica. As a mineraloid , no unit cell describes the structure of opal. Nevertheless, opals can be roughly divided into those that show no signs of crystalline order ( amorphous opal) and those that show signs of the beginning of crystalline order, commonly termed cryptocrystalline or microcrystalline opal. [ 59 ] Dehydration experiments and infrared spectroscopy have shown that most of the H 2 O in the formula of SiO 2 · n H 2 O of opals is present in the familiar form of clusters of molecular water. Isolated water molecules, and silanols , structures such as SiOH, generally form a lesser proportion of the total and can reside near the surface or in defects inside the opal.
The structure of low-pressure polymorphs of anhydrous silica consists of frameworks of fully corner bonded tetrahedra of SiO 4 . The higher temperature polymorphs of silica cristobalite and tridymite are frequently the first to crystallize from amorphous anhydrous silica, and the local structures of microcrystalline opals also appear to be closer to that of cristobalite and tridymite than to quartz. The structures of tridymite and cristobalite are closely related and can be described as hexagonal and cubic close-packed layers. It is therefore possible to have intermediate structures in which the layers are not regularly stacked.
Microcrystalline opal or Opal-CT has been interpreted as consisting of clusters of stacked cristobalite and tridymite over very short length scales. The spheres of opal in microcrystalline opal are themselves made up of tiny nanocrystalline blades of cristobalite and tridymite. Microcrystalline opal has occasionally been further subdivided in the literature. Water content may be as high as 10 wt%. [ 60 ] Opal-CT, also called lussatine or lussatite , is interpreted as consisting of localized order of α-cristobalite with a lot of stacking disorder. Typical water content is about 1.5 wt%.
Two broad categories of noncrystalline opals, sometimes just referred to as "opal-A" ("A" stands for "amorphous"), [ 61 ] have been proposed. The first of these is opal-AG consisting of aggregated spheres of silica, with water filling the space in between. Precious opal and potch opal are generally varieties of this, the difference being in the regularity of the sizes of the spheres and their packing. The second "opal-A" is opal-AN or water-containing amorphous silica-glass. Hyalite is another name for this.
Noncrystalline silica in siliceous sediments is reported to gradually transform to opal-CT and then opal-C as a result of diagenesis , due to the increasing overburden pressure in sedimentary rocks, as some of the stacking disorder is removed. [ 62 ]
The surface of opal in contact with water is covered by siloxane bonds (≡Si–O–Si≡) and silanol groups (≡Si–OH). This makes the opal surface very hydrophilic and capable of forming numerous hydrogen bonds .
The word 'opal' is adapted from the Latin term opalus . The origin of this word in turn is a matter of debate, but most modern references suggest it is adapted from the Sanskrit word úpala meaning ‘precious stone’. [ 5 ]
As references to the gem are made by Pliny the Elder , one theory attributed the name's origin to Roman mythology: to have been adapted from Ops , the wife of Saturn , and goddess of fertility. (The portion of Saturnalia devoted to Ops was "Opalia", similar to opalus .)
Another common claim was that the term was adapted from the Ancient Greek word, opallios . This word has two meanings, one is related to "seeing" and forms the basis of the English words like "opaque"; the other is "other" as in "alias" and "alter". It is claimed that opalus combined these uses, meaning "to see a change in color". However, historians have noted the first appearances of opallios do not occur until after the Romans had taken over the Greek states in 180 BC and they had previously used the term paederos . [ 5 ]
However, the argument for the Sanskrit origin is strong. The term first appears in Roman references around 250 BC, at a time when the opal was valued above all other gems. The opals were supplied by traders from the Bosporus , who claimed the gems were being supplied from India. Before this, the stone was referred to by a variety of names, but these fell from use after 250 BC.
In the Middle Ages, opal was considered a stone that could provide great luck because it was believed to possess all the virtues of each gemstone whose color was represented in the color spectrum of the opal. [ 63 ] It was also said to grant invisibility if wrapped in a fresh bay leaf and held in the hand. [ 63 ] [ 64 ] As a result, the opal was seen as the patron gemstone for thieves during the medieval period . [ 65 ] Following the publication of Sir Walter Scott 's Anne of Geierstein in 1829, opal acquired a less auspicious reputation. In Scott's novel, the Baroness of Arnheim wears an opal talisman with supernatural powers. When a drop of holy water falls on the talisman, the opal turns into a colorless stone and the Baroness dies soon thereafter. Due to the popularity of Scott's novel, people began to associate opals with bad luck and death. [ 63 ] Within a year of the publishing of Scott's novel in April 1829, the sale of opals in Europe dropped by 50%, and remained low for the next 20 years or so. [ 66 ]
Even as recently as the beginning of the 20th century, it was believed that when a Russian saw an opal among other goods offered for sale, he or she should not buy anything more, as the opal was believed to embody the evil eye . [ 63 ]
Opal is considered the birthstone for people born in October. [ 67 ] | https://en.wikipedia.org/wiki/Opal |
Opal is a variety of low-aromatic 91 RON petrol developed in 2005 by BP Australia to combat the rising use of gasoline as an inhalant in remote Indigenous Australian communities. [ 1 ]
Though more expensive to produce, requiring a $0.33/litre Federal subsidy, a 2006 report found it would likely save at least $27 million per year when the social and health costs of petrol-sniffing were taken into account. [ 2 ]
A 2010 senate report showed that the introduction of Opal in 106 communities across remote and regional Australia had led to a 70% drop in petrol sniffing in those communities. [ 3 ]
Typical unleaded petrol contains 25% aromatics , such as toluene , ortho-xylene and para-xylene . In contrast, Opal contains only 5% aromatics, which means that it has less of the toluene and other solvents which produce the intoxication (or "high") that inhalant users are seeking. The Australian Government subsidises Opal's provision and restricts traditional unleaded petrol in some remote communities. According to BP, the lower volatile component in Opal means that cars using it are less prone to vapour lock . [ 4 ]
Prior to the introduction of Opal, Comgas (a brand of the aviation fuel avgas ) was used in many communities to discourage use of fuel as an inhalant. Unlike Opal, however, Comgas contains tetraethyllead (TEL), a poisonous substance that inhibits catalytic converters and is therefore banned for automobile use in most parts of the world especially after the discovery that it increased concentrations of lead particles over the entire earth, including the poles. [ 5 ] | https://en.wikipedia.org/wiki/Opal_(fuel) |
The Opal Storage Specification is a set of specifications for features of data storage devices (such as hard disk drives and solid state drives) that enhance their security. For example, it defines a way of encrypting the stored data so that an unauthorized person who gains possession of the device cannot see the data. That is, it is a specification for self-encrypting drives (SED).
The specification is published by the Trusted Computing Group Storage Workgroup.
The Opal SSC (Security Subsystem Class) is an implementation profile for Storage Devices built to:
The Opal SSC encompasses these functions:
Radboud University researchers indicated in November 2018 that some hardware-encrypted SSDs, including some Opal implementations, had security vulnerabilities. [ 2 ] | https://en.wikipedia.org/wiki/Opal_Storage_Specification |
Open-Architecture-System (OAS) is the main User interface and synthesizer software of the Wersi keyboard line. OAS improves on prior organ interfaces by allowing the user to add sounds, rhythms, third party programs and future software enhancements without changing hardware. Compared to previous organs which relied on buttons, OAS uses a touch screen to make programming easier. OAS can host up to 4 separate VST software instruments, allowing for an expandable system similar to the Korg OASYS . OAS can support dynamic touch and aftertouch, but cannot support horizontal touch like the Yamaha Stagea Electone .
OAS Version 7 expands on previous versions by adding a new effects section. Separate effects are available for the accompaniment section, sequencer and drums. Added effects include delay, reverb, phasing, wah wah, distortion, compressor, and flanger. In addition, version 7 includes 300 new sounds, 700 sounds in total.
Version 7 adds the Wersi Open Art Arranger. This software enables the Wersi to use all Yamaha styles, [ 1 ] including those from the Tyros 2 .
This computing article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Open-Architecture-System |
In chemistry , an open-chain compound (or open chain compound ) or acyclic compound (Greek prefix α 'without' and κύκλος 'cycle') is a compound with a linear structure, rather than a cyclic one. [ 1 ] An open-chain compound having no side groups is called a straight-chain compound (also spelled as straight chain compound). [ 2 ] [ 3 ] Many of the simple molecules of organic chemistry , such as the alkanes and alkenes , have both linear and ring isomers , that is, both acyclic and cyclic . For those with 4 or more carbons, the linear forms can have straight-chain or branched-chain isomers. The lowercase prefix n- denotes the straight-chain isomer; for example, n -butane is straight-chain butane , whereas i -butane is isobutane . Cycloalkanes are isomers of alkenes, not of alkanes, because the ring's closure involves a C-C bond. Having no rings (aromatic or otherwise), all open-chain compounds are aliphatic .
Typically in biochemistry , some isomers are more prevalent than others. For example, in living organisms, the open-chain isomer of glucose usually exists only transiently, in small amounts; D-glucose is the usual isomer; and L-glucose is rare.
Straight-chain molecules are often not literally straight, in the sense that their bond angles are often not 180°, but the name reflects that they are schematically straight. For example, the straight-chain alkanes are wavy or "puckered", as the models below show. | https://en.wikipedia.org/wiki/Open-chain_compound |
In fluid mechanics and hydraulics , open-channel flow is a type of liquid flow within a conduit with a free surface , known as a channel . [ 1 ] [ 2 ] The other type of flow within a conduit is pipe flow . These two types of flow are similar in many ways but differ in one important respect: open-channel flow has a free surface, whereas pipe flow does not, resulting in flow dominated by gravity but not hydraulic pressure .
Open-channel flow can be classified and described in various ways based on the change in flow depth with respect to time and space. [ 3 ] The fundamental types of flow dealt with in open-channel hydraulics are:
The behavior of open-channel flow is governed by the effects of viscosity and gravity relative to the inertial forces of the flow. Surface tension has a minor contribution, but does not play a significant enough role in most circumstances to be a governing factor. Due to the presence of a free surface, gravity is generally the most significant driver of open-channel flow; therefore, the ratio of inertial to gravity forces is the most important dimensionless parameter. [ 4 ] The parameter is known as the Froude number , and is defined as: Fr = U g D {\displaystyle {\text{Fr}}={U \over {\sqrt {gD}}}} where U {\displaystyle U} is the mean velocity, D {\displaystyle D} is the characteristic length scale for a channel's depth, and g {\displaystyle g} is the gravitational acceleration . Depending on the effect of viscosity relative to inertia, as represented by the Reynolds number , the flow can be either laminar , turbulent , or transitional . However, it is generally acceptable to assume that the Reynolds number is sufficiently large so that viscous forces may be neglected. [ 4 ]
It is possible to formulate equations describing three conservation laws for quantities that are useful in open-channel flow: mass, momentum, and energy. The governing equations result from considering the dynamics of the flow velocity vector field v {\displaystyle {\bf {v}}} with components v = ( u v w ) T {\displaystyle {\bf {v}}={\begin{pmatrix}u&v&w\end{pmatrix}}^{T}} . In Cartesian coordinates , these components correspond to the flow velocity in the x, y, and z axes respectively.
To simplify the final form of the equations, it is acceptable to make several assumptions:
The general continuity equation , describing the conservation of mass, takes the form: ∂ ρ ∂ t + ∇ ⋅ ( ρ v ) = 0 {\displaystyle {\partial \rho \over {\partial t}}+\nabla \cdot (\rho {\bf {v}})=0} where ρ {\displaystyle \rho } is the fluid density and ∇ ⋅ ( ) {\displaystyle \nabla \cdot ()} is the divergence operator. Under the assumption of incompressible flow, with a constant control volume V {\displaystyle V} , this equation has the simple expression ∇ ⋅ v = 0 {\displaystyle \nabla \cdot {\bf {v}}=0} . However, it is possible that the cross-sectional area A {\displaystyle A} can change with both time and space in the channel. If we start from the integral form of the continuity equation: d d t ∫ V ρ d V = − ∫ V ∇ ⋅ ( ρ v ) d V {\displaystyle {d \over {dt}}\int _{V}\rho \;dV=-\int _{V}\nabla \cdot (\rho {\bf {v}})\;dV} it is possible to decompose the volume integral into a cross-section and length, which leads to the form: d d t ∫ x ( ∫ A ρ d A ) d x = − ∫ x [ ∫ A ∇ ⋅ ( ρ v ) d A ] d x {\displaystyle {d \over {dt}}\int _{x}\left(\int _{A}\rho \;dA\right)dx=-\int _{x}\left[\int _{A}\nabla \cdot (\rho {\bf {v}})\;dA\right]dx} Under the assumption of incompressible, 1D flow, this equation becomes: d d t ∫ x ( ∫ A d A ) d x = − ∫ x ∂ ∂ x ( ∫ A u d A ) d x {\displaystyle {d \over {dt}}\int _{x}\left(\int _{A}dA\right)dx=-\int _{x}{\partial \over {\partial x}}\left(\int _{A}u\;dA\right)dx} By noting that ∫ A d A = A {\displaystyle \int _{A}dA=A} and defining the volumetric flow rate Q = ∫ A u d A {\displaystyle Q=\int _{A}u\;dA} , the equation is reduced to: ∫ x ∂ A ∂ t d x = − ∫ x ∂ Q ∂ x d x {\displaystyle \int _{x}{\partial A \over {\partial t}}\;dx=-\int _{x}{\partial Q \over {\partial x}}dx} Finally, this leads to the continuity equation for incompressible, 1D open-channel flow:
∂ A ∂ t + ∂ Q ∂ x = 0 {\displaystyle {\partial A \over {\partial t}}+{\partial Q \over {\partial x}}=0}
The momentum equation for open-channel flow may be found by starting from the incompressible Navier–Stokes equations : ∂ v ∂ t ⏟ Local Change + v ⋅ ∇ v ⏟ Advection ⏞ Inertial Acceleration = − 1 ρ ∇ p ⏟ Pressure Gradient + ν Δ v ⏟ Diffusion − ∇ Φ ⏟ Gravity + F ⏟ External Forces {\displaystyle \overbrace {\underbrace {\partial {\bf {v}} \over {\partial t}} _{\begin{smallmatrix}{\text{Local}}\\{\text{Change}}\end{smallmatrix}}+\underbrace {{\bf {v}}\cdot \nabla {\bf {v}}} _{\text{Advection}}} ^{\text{Inertial Acceleration}}=-\underbrace {{1 \over {\rho }}\nabla p} _{\begin{smallmatrix}{\text{Pressure}}\\{\text{Gradient}}\end{smallmatrix}}+\underbrace {\nu \Delta {\bf {v}}} _{\text{Diffusion}}-\underbrace {\nabla \Phi } _{\text{Gravity}}+\underbrace {\bf {F}} _{\begin{smallmatrix}{\text{External}}\\{\text{Forces}}\end{smallmatrix}}} where p {\displaystyle p} is the pressure , ν {\displaystyle \nu } is the kinematic viscosity , Δ {\displaystyle \Delta } is the Laplace operator , and Φ = g z {\displaystyle \Phi =gz} is the gravitational potential . By invoking the high Reynolds number and 1D flow assumptions, we have the equations: ∂ u ∂ t + u ∂ u ∂ x = − 1 ρ ∂ p ∂ x + F x − 1 ρ ∂ p ∂ z − g = 0 {\displaystyle {\begin{aligned}{\partial u \over {\partial t}}+u{\partial u \over {\partial x}}&=-{1 \over {\rho }}{\partial p \over {\partial x}}+F_{x}\\-{1 \over {\rho }}{\partial p \over {\partial z}}-g&=0\end{aligned}}} The second equation implies a hydrostatic pressure p = ρ g ζ {\displaystyle p=\rho g\zeta } , where the channel depth η ( t , x ) = ζ ( t , x ) − z b ( x ) {\displaystyle \eta (t,x)=\zeta (t,x)-z_{b}(x)} is the difference between the free surface elevation ζ {\displaystyle \zeta } and the channel bottom z b {\displaystyle z_{b}} . Substitution into the first equation gives: ∂ u ∂ t + u ∂ u ∂ x + g ∂ ζ ∂ x = F x ⟹ ∂ u ∂ t + u ∂ u ∂ x + g ∂ η ∂ x − g S = F x {\displaystyle {\partial u \over {\partial t}}+u{\partial u \over {\partial x}}+g{\partial \zeta \over {\partial x}}=F_{x}\implies {\partial u \over {\partial t}}+u{\partial u \over {\partial x}}+g{\partial \eta \over {\partial x}}-gS=F_{x}} where the channel bed slope S = − d z b / d x {\displaystyle S=-dz_{b}/dx} . To account for shear stress along the channel banks, we may define the force term to be: F x = − 1 ρ τ R {\displaystyle F_{x}=-{1 \over {\rho }}{\tau \over {R}}} where τ {\displaystyle \tau } is the shear stress and R {\displaystyle R} is the hydraulic radius . Defining the friction slope S f = τ / ρ g R {\displaystyle S_{f}=\tau /\rho gR} , a way of quantifying friction losses, leads to the final form of the momentum equation:
∂ u ∂ t + u ∂ u ∂ x + g ∂ η ∂ x + g ( S f − S ) = 0 {\displaystyle {\partial u \over {\partial t}}+u{\partial u \over {\partial x}}+g{\partial \eta \over {\partial x}}+g(S_{f}-S)=0}
To derive an energy equation, note that the advective acceleration term v ⋅ ∇ v {\displaystyle {\bf {v}}\cdot \nabla {\bf {v}}} may be decomposed as: v ⋅ ∇ v = ω × v + 1 2 ∇ ‖ v ‖ 2 {\displaystyle {\bf {v}}\cdot \nabla {\bf {v}}=\omega \times {\bf {v}}+{1 \over {2}}\nabla \|{\bf {v}}\|^{2}} where ω {\displaystyle \omega } is the vorticity of the flow and ‖ ⋅ ‖ {\displaystyle \|\cdot \|} is the Euclidean norm . This leads to a form of the momentum equation, ignoring the external forces term, given by: ∂ v ∂ t + ω × v = − ∇ ( 1 2 ‖ v ‖ 2 + p ρ + Φ ) {\displaystyle {\partial {\bf {v}} \over {\partial t}}+\omega \times {\bf {v}}=-\nabla \left({1 \over {2}}\|{\bf {v}}\|^{2}+{p \over {\rho }}+\Phi \right)} Taking the dot product of v {\displaystyle {\bf {v}}} with this equation leads to: ∂ ∂ t ( 1 2 ‖ v ‖ 2 ) + v ⋅ ∇ ( 1 2 ‖ v ‖ 2 + p ρ + Φ ) = 0 {\displaystyle {\partial \over {\partial t}}\left({1 \over {2}}\|{\bf {v}}\|^{2}\right)+{\bf {v}}\cdot \nabla \left({1 \over {2}}\|{\bf {v}}\|^{2}+{p \over {\rho }}+\Phi \right)=0} This equation was arrived at using the scalar triple product v ⋅ ( ω × v ) = 0 {\displaystyle {\bf {v}}\cdot (\omega \times {\bf {v}})=0} . Define E {\displaystyle E} to be the energy density : E = 1 2 ρ ‖ v ‖ 2 ⏟ Kinetic Energy + ρ Φ ⏟ Potential Energy {\displaystyle E=\underbrace {{1 \over {2}}\rho \|{\bf {v}}\|^{2}} _{\begin{smallmatrix}{\text{Kinetic}}\\{\text{Energy}}\end{smallmatrix}}+\underbrace {\rho \Phi } _{\begin{smallmatrix}{\text{Potential}}\\{\text{Energy}}\end{smallmatrix}}} Noting that Φ {\displaystyle \Phi } is time-independent, we arrive at the equation: ∂ E ∂ t + v ⋅ ∇ ( E + p ) = 0 {\displaystyle {\partial E \over {\partial t}}+{\bf {v}}\cdot \nabla (E+p)=0} Assuming that the energy density is time-independent and the flow is one-dimensional leads to the simplification: E + p = C {\displaystyle E+p=C} with C {\displaystyle C} being a constant; this is equivalent to Bernoulli's principle . Of particular interest in open-channel flow is the specific energy e = E / ρ g {\displaystyle e=E/\rho g} , which is used to compute the hydraulic head h {\displaystyle h} that is defined as:
h = e + p ρ g = u 2 2 g + z + p γ {\displaystyle {\begin{aligned}h&=e+{p \over {\rho g}}\\&={u^{2} \over {2g}}+z+{p \over {\gamma }}\end{aligned}}}
with γ = ρ g {\displaystyle \gamma =\rho g} being the specific weight . However, realistic systems require the addition of a head loss term h f {\displaystyle h_{f}} to account for energy dissipation due to friction and turbulence that was ignored by discounting the external forces term in the momentum equation. | https://en.wikipedia.org/wiki/Open-channel_flow |
The open-circuit time constant (OCT) method is an approximate analysis technique used in electronic circuit design to determine the corner frequency of complex circuits . It is a special case of zero-value time constant (ZVT) method technique when reactive elements consist of only capacitors. The zero-value time (ZVT) constant method itself is a special case of the general Time- and Transfer Constant (TTC) analysis that allows full evaluation of the zeros and poles of any lumped LTI systems of with both inductors and capacitors as reactive elements using time constants and transfer constants . The OCT method provides a quick evaluation, and identifies the largest contributions to time constants as a guide to the circuit improvements.
The basis of the method is the approximation that the corner frequency of the amplifier is determined by the term in the denominator of its transfer function that is linear in frequency. This approximation can be extremely inaccurate in some cases where a zero in the numerator is near in frequency. [ 1 ] If all the poles are real and there are no zeros, this approximation is always conservative, in the sense that the inverse of the sum of the zero-value time constants is less than the actual corner frequency of the circuit. [ 2 ]
The method also uses a simplified method for finding the term linear in frequency based upon summing the RC-products for each capacitor in the circuit, where the resistor R for a selected capacitor is the resistance found by inserting a test source at its site and setting all other capacitors to zero. Hence the name zero-value time constant technique .
Figure 1 shows a simple RC low-pass filter. Its transfer function is found using Kirchhoff's current law as follows. At the output,
where V 1 is the voltage at the top of capacitor C 1 . At the center node:
Combining these relations the transfer function is found to be:
The linear term in j ω in this transfer function can be derived by the following method, which is an application of the open-circuit time constant method to this example.
In effect, it is as though each capacitor charges and discharges through the resistance found in the circuit when the other capacitor is an open circuit.
The open circuit time constant procedure provides the linear term in j ω regardless of how complex the RC network becomes. This was originally developed and proven by calculating the co-factors of the admittance matrix by Thornton and Searle. [ 3 ] A more intuitive inductive proof of this (and other properties of TTC) was later developed by Hajimiri. [ 4 ]
For a complex circuit, the procedure consists of following the above rules, going through all the capacitors in the circuit. A more general derivation is found in Gray and Meyer. [ 5 ]
So far the result is general, but an approximation is introduced to make use of this result: the assumption is made that this linear term in j ω determines the corner frequency of the circuit.
That assumption can be examined more closely using the example of Figure 1: suppose the time constants of this circuit are τ 1 and τ 2 ; that is:
Comparing the coefficients of the linear and quadratic terms in j ω, there results:
One of the two time constants will be the longest; let it be τ 1 . Suppose for the moment that it is much larger than the other, τ 1 >> τ 2 . In this case, the approximations hold that:
and
In other words, substituting the RC-values:
and
where ( ^ ) denotes the approximate result. As an aside, notice that the circuit time constants both involve both capacitors; in other words, in general the circuit time constants are not decided by any single capacitor. Using these results, it is easy to explore how well the corner frequency (the 3 dB frequency) is given by
as the parameters vary. Also, the exact transfer function can be compared with the approximate one, that is,
Of course agreement is good when the assumption τ 1 >> τ 2 is accurate.
Figure 2 illustrates the approximation. The x-axis is the ratio τ 1 / τ 2 on a logarithmic scale. An increase in this variable means the higher pole is further above the corner frequency. The y-axis is the ratio of the OCTC (open-circuit time constant) estimate to the true time constant. For the lowest pole use curve T_1; this curve refers to the corner frequency; and for the higher pole use curve T_2. The worst agreement is for τ 1 = τ 2 . In this case τ ^ 1 = 2 τ 1 and the corner frequency is a factor of 2 too small. The higher pole is a factor of 2 too high (its time constant is half of the real value).
In all cases, the estimated corner frequency is closer than a factor of two from the real one, and always is conservative that is, lower than the real corner, so the actual circuit will behave better than predicted. However, the higher pole always is optimistic , that is, predicts the high pole at a higher frequency than really is the case. To use these estimates for step response predictions, which depend upon the ratio of the two pole frequencies (see article on pole splitting for an example), Figure 2 suggests a fairly large ratio of τ 1 / τ 2 is needed for accuracy because the errors in τ ^ 1 and τ ^ 2 reinforce each other in the ratio τ ^ 1 / τ ^ 2 .
The open-circuit time constant method focuses upon the corner frequency alone, but as seen above, estimates for higher poles also are possible.
Application of the open-circuit time constant method to a number of single transistor amplifier stages can be found in Pittet and Kandaswamy. [ 6 ] | https://en.wikipedia.org/wiki/Open-circuit_time_constant_method |
The open-design movement involves the development of physical products, machines and systems through use of publicly shared design information. This includes the making of both free and open-source software (FOSS) as well as open-source hardware . The process is generally facilitated by the Internet and often performed without monetary compensation. The goals and philosophy of the movement are identical to that of the open-source movement , but are implemented for the development of physical products rather than software. [ 5 ] Open design is a form of co-creation , where the final product is designed by the users, rather than an external stakeholder such as a private company.
Sharing of manufacturing information can be traced back to the 18th and 19th century. [ 6 ] [ 7 ] Aggressive patenting put an end to that period of extensive knowledge sharing. [ 8 ] More recently, principles of open design have been related to the free and open-source software movements. [ 9 ] In 1997 Eric S. Raymond , Tim O'Reilly and Larry Augustin established "open source" as an alternative expression to "free software", and in 1997 Bruce Perens published The Open Source Definition . In late 1998, Dr. Sepehr Kiani (a PhD in mechanical engineering from MIT) realized that designers could benefit from open source policies, and in early 1999 he convinced Dr. Ryan Vallance and Dr. Samir Nayfeh of the potential benefits of open design in machine design applications. [ 10 ] Together they established the Open Design Foundation (ODF) as a non-profit corporation, and set out to develop an Open Design Definition. [ 10 ]
The idea of open design was taken up, either simultaneously or subsequently, by several other groups and individuals. The principles of open design are closely similar to those of open-source hardware design, which emerged in March 1998 when Reinoud Lamberts of the Delft University of Technology proposed on his "Open Design Circuits" website the creation of a hardware design community in the spirit of free software. [ 11 ]
Ronen Kadushin coined the title "Open Design" in his 2004 Master's thesis, and the term was later formalized in the 2010 Open Design Manifesto. [ 12 ]
The open-design movement currently unites two trends. On one hand, people apply their skills and time on projects for the common good , perhaps where funding or commercial interest is lacking, for developing countries or to help spread ecological or cheaper technologies. On the other hand, open design may provide a framework for developing advanced projects and technologies that might be beyond the resource of any single company or country and involve people who, without the copyleft mechanism, might not collaborate otherwise. There is now also a third trend, where these two methods come together to use high-tech open-source (e.g. 3D printing) but customized local solutions for sustainable development . [ 13 ] Open Design holds great potential in driving future innovation as recent research has proven that stakeholder users working together produce more innovative designs than designers consulting users through more traditional means. [ 14 ] The open-design movement may arguably organize production by prioritising socio-ecological well-being over corporate profits, over-production and excess consumption. [ 15 ]
The open-design movement is currently fairly nascent but holds great potential for the future. In some respects design and engineering are even more suited to open collaborative development than the increasingly common open-source software projects, because with 3D models and photographs the concept can often be understood visually. It is not even necessary that the project members speak the same languages to usefully collaborate. [ citation needed ]
However, there are certain barriers to overcome for open design when compared to software development where there are mature and widely used tools available and the duplication and distribution of code cost next to nothing. Creating, testing and modifying physical designs is not quite so straightforward because of the effort, time and cost required to create the physical artefact; although with access to emerging flexible computer-controlled manufacturing techniques the complexity and effort of construction can be significantly reduced (see tools mentioned in the fab lab article).
Open design was considered in 2012 a fledgling movement consisting of several unrelated or loosely related initiatives. [ 16 ] Many of these organizations are single, funded projects, while a few organizations are focusing on an area needing development. In some cases (e.g. Thingiverse for 3D printable designs or Appropedia for open source appropriate technology ) organizations are making an effort to create a centralized open source design repository as this enables innovation. [ 17 ] Notable organizations include: | https://en.wikipedia.org/wiki/Open-design_movement |
In game theory , an open-loop model is the one where players cannot observe the play of their opponents, as opposed to a closed-loop model, where all past play is common knowledge . The solution to an open-loop model is called "open-loop equilibrium".
Open loop models are more tractable, which is why they are sometimes preferred to closed-loop models even when the latter is a better description of reality. [ 1 ]
This game theory article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/Open-loop_model |
Open-source architecture is an emerging paradigm advocating new procedures in the imagination and formation of virtual and real spaces within a universal infrastructure . Drawing from references as diverse as open-source culture, modular design , avant-garde architectural, science fiction , language theory, and neuro-surgery , it adopts an inclusive approach as per spatial design towards a collaborative use of design and design tools by professionals and ordinary citizen users. The umbrella term citizen-centered design harnesses the notion of open-source architecture , which in itself involves the non-building architecture of computer networks, and goes beyond it to the movement that encompasses the building design professions, as a whole.
Citizen-centered design emerged in 1999 through academic research conducted in leading universities such as the University of Texas (SUPA), [ 1 ] as well as professional practice organizations like the Earthnomad Foundation [ 2 ] and ARK Tectonics. [ 3 ] This movement aimed to bridge the gap between design and public policy, positioning itself at their intersection. Over the ensuing decades, the movement expanded globally, encompassing various initiatives ranging from organizational efforts to community design centers sponsored by academic institutions. The principles of citizen-centered design, and by extension, open-source architecture, were founded on the accumulated body of knowledge from citizen participation research and practices dating back to the 1960s on citizen participation research and practices.
Around the turn of the century, citizen engagement research and practices were reformulated through the lens of more effective approaches and paradigms in the social and applied sciences, through the seminal work of Dr. Schaban-Maurer (2013), architect, urban planner and author of the deliberative design and phronetic engagement resource "Rise of the Citizen Practitioner" [ 4 ] Dr. Schaban-Maurer laid out the principles and precepts of his 'Life-Experience Narrative Exchange' methodology in the Mindful Policy Engagement field, which he founded in 2013, with the ground-breaking work 'The Roles of the Citizen Practitioner in Citizen Engagement for Architecture, Urban Design and Urban Planning Policy: A Phronesis-Based Approach" [ 5 ] The work provides rigorous theoretical basis for a body of best case studies and best practices of citizen-centered architecture, urban design and urban planning, as well as, urban and public policy. According to Dr. Schaban-Maurer, the (LENE) methodology leads to meaningful and effective design practices by integrating their processes with the principles of Phronetic Engagement and Mindful Policy into a new field of inquiry; 'Mindful Policy Engagement.' (Schaban-Maurer, 2013: 11) [ 5 ]
Since its inception, the citizen-centered design movement has expanded its influence beyond architecture, engaging practitioners and academics from various fields in interdisciplinary collaborations, publications, conferences, and international exhibitions. Over the last decade, open-source architecture, mindful policy engagement, and citizen-centered design have given rise to smaller subsets with different names, including 'social impact design', 'public interest design', and the 'open architecture network'. Practitioners in these fields integrate design practice with social service to address pressing community needs. These efforts, which began decades ago, are propelled forward by new sensibilities and a continued commitment from architects, urban designers, planners, policymakers, and other stakeholders. They aim to engage and harness the knowledge of ordinary citizens in the design, development, and implementation of urban policies and projects that directly impact the communities where we all live and work.
Cooking is often hailed as an early form of open source; vernacular architecture – producing recipes for everyday buildings – is another form of early lo-fi open-source culture, openly sharing and optimising technologies for building.
New economic models, exemplified by incremental microdonations and crowd-funding strategies like Sponsume and Kickstarter , offer new modes of project initiation and development, destabilising the traditionally feudal hierarchy of client/architect/occupant. Financing of private projects increasingly moves to the public domain, offering mass rather than singular ownership, whereas funding of public projects can be derived from more flexible, responsive frameworks than simple levies or taxation. Open-source architecture should have particular appeal for builders entirely outside the mainstream economy, such as squatters, refugees and the military.
Open-source architecture relies upon amateurs as much as experienced professionals, the "genius of the mass" as much as that of the individual, [ 5 ] eroding the binary distinction between author and audience. Like social software, it recognises the core role of multiple users at every stage of the project – whether as clients or communities, designers or occupants; at its best, it harnesses powerful network effects to scale systems effectively. It is typically democratic, enshrining principles of open access and participation, though political variations range from stealth authoritarianism to communitarian consensualism.
Traditional developments require engagement programmes in which the 'community' is 'consulted' with respect to incoming developments, often with blunt tools such as focus groups, which often result in lack of representation and input, or at worst can result in NIMBYism . With crowd-funded models, forms of engagement are built into the process, enabling a kind of emergent urbanism, in which use of space is optimised on terms set by its users. This reclamation of people's power can be seen as a soft, spatial version of Hacktivism . Open-source architecture is likely to suffer some of the organizational drawbacks of open-source software, such as forking of projects, abandoned projects, the emergence of cliques and incompatibility with the installed base of buildings. Organized campaigns of fear, uncertainty and doubt are probable.
An important aspect of open-source architecture is the emergence of open standards of collaboration. The establishment of common, open, modular standards (such as the grid proposed by the OpenStructures project [ 6 ] addresses the problem of hardware compatibility and the interface between components, allowing collaborative efforts across networks in which everyone designs for everyone. The establishment of universal standards also encourages the growth of networks of non-monetary exchange (knowledge, parts, components, ideas) and remote collaboration.
Mass customisation replaces standardisation as algorithms enable the generation of related but differentiated species of design objects. Parametric design tools like Grasshopper 3D , GenerativeComponents , Revit and Digital Project enable new user groups to interact with, navigate and modify the virtual designs, and to test and experience arrays of options at unprecedented low cost – recognizing laypeople as design decision making agents rather than just consumers. Open-source codes and scripts enable design communities to share and compare information and to collectively optimise production through modular components, accelerating the historical accumulation of shared knowledge. BIM (Building Information Modelling) and related collaboration tools and practices enable cross-disciplinary co-location of design information and integration of a range of platforms and timescales. Rapid prototyping and other 3D printing technologies enable instant production of physical artefacts, both representational and functional, even at an architectural scale, to an ever-wider audience.
There are severe criticisms of the use of currently popular design software, however, because of the impossibility of future residents and users to access them. P2P Urbanism promotes low-tech design solutions that collect traditionally-derived design knowledge and makes it available on an open-source web platform. This focus instead promotes traditional local materials and building techniques in vernacular architecture and is entirely distinct from that of the virtual design groups focusing upon the extremely expensive parametric design. The proponents of P2P Urbanism also philosophically oppose what they see as "fashionable" design approaches because of a link to unsustainable products, strong commercial interests, and total control by only a few participants—which is the opposite of opening up design to the whole population. In their view, the point of open-source design should be to facilitate users designing and building their own dwellings, not to continue promoting a design elite that includes current starchitects .
The burgeoning open-source hardware movement enables sharing of and collaboration on the hardware involved in designing kinetic or smart environments that tightly integrate software, hardware, and mechanisms. Through these various tools, informed by sensor data, design becomes an ongoing, evolutionary process, as opposed to the one-off, disjointed fire-and-forget method of traditional design. This is an acknowledgement of the fact that design has always been an unending process, as well as a collaboration between users and designers. Operating systems for the design, construction and occupancy phases become possible, created as open platforms stimulating a rich ecosystem of 'apps'. Various practices jostle to become the Linux of architectural software, engaging in 'platform plays' at different scales rather than delivery of plans and sections. Embedded sensing and computing increasingly mesh all materials within the larger " Internet of things ", evolving ever closer towards Bruce Sterling 's vision of a world of Spimes . Materials communicate their position and state during fabrication and construction, aiding positioning, fixing and verification, and continue to communicate with distributed databases for the extent of their lifetime.
Today's OSArc enables inhabitants to control and shape their personal environment – “to Inhabit is to Design”, as John Habraken put it. This aspect is enhanced by today's fully sentient networked spaces, constantly communicating their various properties, states and attributes – often through decentralised and devolved systems. Crucial system feedback is supplied by a wide range of users and occupants, often either by miniature electronic devices or mobile phones – crowdsourcing (like crowd-funding) large volumes of small data feeds to provide accurate and expansive real-time information. Personalisation replaces standardisation as spaces 'intelligently' recognise and respond to individual occupants. Representations of spaces become as vital after construction as they are before; real-time monitoring , feedback and ambient display become integral elements to the ongoing life of spaces and objects. Maintenance and operations become extended inseparable phases of the construction process; a building is never "complete" in open-source architecture's world of growth and change.
If tomorrow's buildings and cities will be like "computers to live in" (see also: smart city ) open-source architecture provides an open, collaborative framework for writing their operating software in real-world conditions reflecting the principles of the citizen-centered architecture movement, as well as, the mindful policy engagement field, namely, unique designs for unique contexts, reflecting individual users' values through value rational planning and engagement-based praxis. | https://en.wikipedia.org/wiki/Open-source_architecture |
OpenAtom is a massively parallel quantum chemistry application written in Charm++ for simulations on supercomputers. Its developmental version was called LeanCP . Many important problems in material science , chemistry , solid-state physics , and biophysics require a modeling approach based on fundamental quantum mechanical principles. A particular approach that has proved to be relatively efficient and useful is Car-Parrinello ab initio molecular dynamics (CPAIMD). It is widely used to study systems consisting of hundreds to thousands of atoms. CPAIMD computations involve many interdependent phases with high communication overhead including multiple concurrent sparse 3D fast Fourier transforms (3D-FFTs), non-square matrix multiplies and few concurrent dense 3D-FFTs.
Parallelization of this approach beyond a few hundred processors is challenging, due to the complex dependencies among various subcomputations, which lead to complex communication optimization and load balancing problems. Using Charm++ and its concept of processor virtualization, the phases are discretized into multiple virtual processors which are, in turn, mapped flexibly onto physical processors, thereby allowing significant interleaving of work. Interleaving is enhanced through both architecturally independent methods and network topology aware mapping techniques. OpenAtom has shown good scaling up to 262,144 cores of IBM Blue Gene/Q and 131,072 cores of Blue Waters, a Cray XE6/XK7 system at NCSA.
OpenAtom is freely available for download at the OpenAtom webpage . Published papers can also be found at the website.
This article about molecular modelling software is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OpenAtom |
The OpenBSD Journal is an online newspaper dedicated to coverage of OpenBSD software and related events. The OpenBSD Journal is widely recognized as a reliable source of OpenBSD-related information. [ 1 ] [ 2 ] [ 3 ] It is a primary reporter for such events as Hackathons . The site also hosts the OpenBSD developers' blogs.
The OpenBSD Journal was founded in 2000 and operated until 1 April 2004 at deadly.org , On 1 April 2004 the editors James Phillips and Jose Nazario announced that the site ceased its operation. [ 4 ] Daniel Hartmeier backed up the contents of the journal in order to preserve them. [ 1 ] Further investigation to the articles' structure lead to creation of CGI -based engine that would enable access to the deadly.org's content on a backup server. Consequently, the functionality of adding new articles was implemented and the previous editors allowed to re-publish articles. The OpenBSD Journal was therefore reintroduced at undeadly .org on 9 April 2004. [ 5 ]
This World Wide Web –related article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OpenBSD_Journal |
The OpenBSD operating system focuses on security and the development of security features. [ 1 ] [ 2 ] : xxvii [ 3 ] According to author Michael W. Lucas, OpenBSD "is widely regarded as the most secure operating system available anywhere, under any licensing terms." [ 2 ] : xxix
Bugs and security flaws are often caused by programmer error. A common source of error is the misuse of the strcpy and strcat string functions in the C programming language. There are two common alternatives, strncpy and strncat , but they can also be difficult to understand and easy to misuse, [ 4 ] [ 5 ] so OpenBSD developers Todd C. Miller and Theo de Raadt designed the strlcpy and strlcat functions. [ 6 ] These functions are intended to make it harder for programmers to accidentally leave buffers unterminated or allow them to be overflowed. [ 7 ] They have been adopted by the NetBSD and FreeBSD projects but not by the GNU C Library . [ 8 ]
On OpenBSD, the linker has been changed to issue a warning when unsafe string manipulation functions , such as strcpy , strcat , or sprintf , are found. All occurrences of these functions in the OpenBSD source tree have been replaced. [ citation needed ] In addition, a static bounds checker is included in OpenBSD in an attempt to find other common programming mistakes at compile time. [ 9 ] Other security-related APIs developed by the OpenBSD project include issetugid [ 10 ] and arc4random . [ 11 ]
In a June 2017 email, Theo de Raadt stated that a problem with stable systems was that they could be running for months at a time. Although there is considerable randomization within the kernel, some key addresses remain the same. The project in progress modifies the linker so that on every boot, the kernel is relinked, as well as all other randomizations. This differs from kernel ASLR ; in the email he states that "As a result, every new kernel is unique. The relative offsets between functions and data are unique ... [The current] change is scaffolding to ensure you boot a newly-linked kernel upon every reboot ... so that a new random kernel can be linked together ... On a fast machine it takes less than a second ... A reboot runs the new kernel, and yet another kernel is built for the next boot. The internal deltas between functions inside the kernel are not where an attacker expects them to be, so he'll need better info leaks". [ 12 ]
OpenBSD integrates several technologies to help protect the operating system from attacks such as buffer overflows or integer overflows .
Developed by Hiroaki Etoh, ProPolice is a GCC extension designed to protect applications from stack-smashing attacks . [ 13 ] It does this through a number of operations: local stack variables are reordered to place buffers after pointers, protecting them from corruption in case of a buffer overflow; pointers from function arguments are also placed before local buffers; and a canary value is placed after local buffers which, when the function exits, can sometimes be used to detect buffer overflows. ProPolice chooses whether or not to protect a buffer based on automatic heuristics which judge how vulnerable it is, reducing the performance overhead of the protection. [ vague ] It was integrated in OpenBSD's version GCC in December 2002, and first made available in OpenBSD 3.3; [ 14 ] it was applied to the kernel in release 3.4. [ 15 ] The extension works on all the CPU architectures supported by OpenBSD and is enabled by default, so any C code compiled will be protected without user intervention. [ 16 ]
In May 2004, OpenBSD on the SPARC platform received further stack protection in the form of StackGhost . This makes use of features of the SPARC architecture to help prevent exploitation of buffer overflows. [ 17 ] Support for SPARC64 was added to -current in March 2005.
OpenBSD 3.4 introduced W^X , a memory management scheme to ensure that memory is either writable or executable, but never both, which provides another layer of protection against buffer overflows. While this is relatively easy to implement on a platform like x86-64 , which has hardware support for the NX bit , OpenBSD is one of the few OSes to support this on the generic i386 platform, [ 18 ] which lacks built in per-page execute controls.
During the development cycle of the 3.8 release, changes were made to the malloc memory management functions. In traditional Unix operating systems, malloc allocates more memory by extending the Unix data segment, a practice that has made it difficult to implement strong protection against security problems. [ vague ] The malloc implementation now in OpenBSD makes use of the mmap system call, which was modified so that it returns random memory addresses and ensures that different areas are not mapped next to each other. In addition, allocation of small blocks in shared areas are now randomized and the free function was changed to return memory to the kernel immediately rather than leaving it mapped into the process. A number of additional, optional checks were also added to aid in development. [ citation needed ] These features make program bugs easier to detect and harder to exploit: instead of memory being corrupted or an invalid access being ignored, they often result in a segmentation fault and abortion of the process. This has brought to light several issues with software running on OpenBSD 3.8, particularly with programs reading beyond the start or end of a buffer, a type of bug that would previously not be detected directly but can now cause an error. [ citation needed ] These abilities took more than three years to implement without considerable performance loss.
One of the goals of the OpenBSD project is the integration of facilities and software for strong cryptography into the core operating system. To this end, a number of low-level features are provided, including a source of strong pseudo random numbers ; [ 19 ] built-in cryptographic hash functions and transforms; and support for cryptographic hardware ( OpenBSD Cryptographic Framework ). These abilities are used throughout OpenBSD, including the bcrypt password-hashing algorithm [ 20 ] derived from Bruce Schneier 's Blowfish block cipher , which takes advantage of the CPU-intensive Blowfish key schedule , making brute-force attacks less practical.
In OpenBSD 5.3, support for full disk encryption was introduced, [ 21 ] but enabling it during the installation of OpenBSD had required manual intervention from the user by exiting the installer and entering some commands. Starting from OpenBSD 7.3, the installer supports enabling full disk encryption using a guided procedure, not requiring manual intervention anymore. [ 22 ] [ 23 ]
To protect sensitive information such as passwords from leaking on to disk, where they can persist for many years, OpenBSD supports encryption of swap space. The swap space is split up into many small regions that are each assigned their own encryption key, which is generated randomly and automatically with no input from the user, held entirely in memory, and never written to disk except when hibernating ; as soon as the data in a region is no longer required, OpenBSD discards its encryption key, effectively transforming the data in that region into useless garbage. [ 24 ] Toggling this feature can be done using a single sysctl configuration option, and doesn't require any prior setup, disk partitioning, or partition-related settings to be done/changed; furthermore, there is no choice of encryption parameters (such as the algorithm or key length to use), as strong parameters are always used. There is no harm and no loss of functionality with this feature, because the encryption keys used to access swapped processes are only lost when the computer crashes (e.g. power loss), after which all operating systems discard the previous contents of the memory and swap anyway, and because hibernation continues to work as usual with this feature. This feature is enabled by default in OpenBSD 3.8 (released in November 2005) and later; OpenBSD, as of 2022, remains the only prominent operating system to have swap encrypted by default independently of disk encryption and its user-provided password. ( Windows requires [ citation needed ] toggling a configuration setting that is not presented in its user-facing Control Panel and Settings apps, and other operating systems, including macOS [ citation needed ] , FreeBSD , [ 25 ] and every Linux -based operating system [ citation needed ] , rely on the existing disk encryption features to encrypt the swap, which often (a) need to be enabled by the user manually, (b) require setup (if disk encryption wasn't chosen during the operating system's installation) which is not as trivial to do as toggling swap encryption on OpenBSD, and (c) use the user-provided password, which users need to remember and could be weak/guessable or even extracted out of the users.)
The network stack also makes heavy use of randomization to increase security and reduce the predictability of various values that may be of use to an attacker, including TCP initial sequence numbers and timestamps, and ephemeral source ports. [ 26 ] A number of features to increase network resilience and availability, including countermeasures for problems with ICMP and software for redundancy, such as CARP and pfsync , are also included. The project was the first to disable the plain-text telnet daemon in favor of the encrypted SSH daemon, in 1999, [ 27 ] and features other integrated cryptographic software such as IPsec . The telnet daemon was completely removed from OpenBSD in 2005 [ 28 ] before the release of OpenBSD version 3.8.
The OpenBSD project had invented their own utility for cryptographic signing and verification of files, signify , [ 29 ] instead of using existing standards and software such as OpenPGP and GnuPG . The creator of the signify utility, Ted Unangst, wrote in 2015, speaking of OpenPGP and GnuPG : "The concerns I had using an existing tool were complexity, quality, and complexity." [ 29 ] This is in line with the project's longtime tendency to reduce complexity, and in turn, reduce the probability of vulnerabilities existing in the software, and help the user understand the software better and make more security-educated decisions. signify is integrated into the base operating system and used for verification of all releases, patches, and packages starting with OpenBSD 5.5. [ 30 ] [ 31 ] In contrast, other Free Software operating systems and security-focused software tend to use OpenPGP for release verification, and as of 2022 continue to do so, including: Debian , a prominent operating system that's also used as a base for other operating systems, including Ubuntu ; [ 32 ] Kali Linux , a specialized operating system for penetration testing , security research, digital forensics , and reverse engineering ; [ 33 ] Qubes OS , a security-focused operating system; [ 34 ] Tor Browser , an anonymous Web browser; [ 35 ] SecureDrop , a software package for journalists and whistleblowers to exchange information securely and anonymously over the Internet; [ 36 ] and VeraCrypt , a software program for on-the-fly encryption and full disk encryption . [ 37 ]
In X11 on OpenBSD, neither the X server nor X clients normally have any escalated direct memory or hardware privileges: When driving X with the Intel(4) or Radeon(4) drivers, these normally interact with the underlying hardware via the Direct Rendering Management(4) kernel interface only, so that lowlevel memory/hardware access is handled solely by the kernel. Other drivers such as WSFB follow a similar pattern. For this reason, X11 on OpenBSD does not open up lowlevel memory or hardware access to user/root programs as is done on some other systems, and as was done in the past, which then needed the user to escalate the machdep.allowaperture setting from its default zero setting, to an unsecure setting. [ citation needed ]
OpenBSD's version of the X Window System (named Xenocara ) has some security modifications. The server and some of the default applications are patched to make use of privilege separation , and OpenBSD provides an "aperture" driver to limit X's access to memory. [ 38 ] However, after work on X security flaws by Loïc Duflot, Theo de Raadt commented that the aperture driver was merely "the best we can do" and that X "violates all the security models you will hear of in a university class." [ 39 ] He went on to castigate X developers for "taking their time at solving this > 10-year-old problem." On November 29, 2006, a VESA kernel driver was developed that permitted X to run, albeit more slowly, without the use of the aperture driver. [ 40 ]
On February 15, 2014, X was further modified to allow it to run without root privileges. [ 41 ] [ 42 ]
After the discovery of a security vulnerability in X, [ 43 ] OpenBSD doesn't support the running of X as a root user and only supports running X via a display manager as a dedicated _x11 user.
Privilege separation , [ 44 ] privilege revocation , chrooting and randomized loading of libraries also play a role in increasing the security of the system. Many of these have been applied to the OpenBSD versions of common programs such as tcpdump and Apache , and to the BSD Authentication system.
OpenBSD has a history of providing its users with full disclosure in relation to various bugs and security breaches detected by the OpenBSD team. [ 45 ] This is exemplified by the project's slogan : "Only two remote holes in the default install, in a heck of a long time!"
OpenBSD is intended to be secure by default, which includes (but is not limited to) having all non-essential services be disabled by default. This is done not only to not require users to learn how and waste time to secure their computers after installing OpenBSD, but also in hope of making users more aware of security considerations, by requiring them to make conscious decisions to enable features that could reduce their security. [ 46 ]
OpenBSD 5.9 included support for the then–new pledge system call (introduced in OpenBSD 5.8 as tame and renamed in 5.9 to pledge ) for restricting process capabilities to a minimal subset required for correct operation. [ 47 ] If the process is compromised and attempts to perform an unintended behavior, it will be terminated by the kernel. OpenBSD 6.4 introduced the unveil system call for restricting filesystem visibility to a minimum level. [ 48 ] pledge and unveil are used together to confine applications, further limiting what they're otherwise permitted to do under the user account they're running as. Since the introduction of pledge , base OpenBSD programs (included out of the box in OpenBSD), applications (handled by their developers), and ports (of applications, handled by the OpenBSD team) have been updated to be confined with pledge and/or unveil . Some examples of third-party applications updated with these features (by their developers or in OpenBSD's app ports) include the Chromium and Firefox web browsers . | https://en.wikipedia.org/wiki/OpenBSD_security_features |
OpenCell is a laboratory in London.
OpenCell is primarily used for work related to biochemical and biomolecular activities such as DNA sequencing . [ 1 ] [ not verified in source ] It opened to the public in June 2018. [ 2 ] The space uses shipping containers to house biotechnology laboratories. [ 3 ] The laboratories contain biotechnology equipment including real-time PCR instruments , Plate reader , Opentrons liquid handling robots, flow hoods, non-ducted fume cupboards, -80, -20 and 4C storage, incubators (static/shaking), centrifuges (1ml-50ml refrigerated), and bench space [ 4 ]
In August 2020, a shipping container laboratory for COVID-19 diagnostics was delivered to the Bailiwick of Jersey. [ 5 ] [ 6 ] The laboratory began processing tests on Tuesday, September 15, with 170 samples, collected from arriving airport passengers, processed within an average of 12 hours. Deputy Medical Officer of Health Dr Ivan Muscat said: “The opening of the covid-19 laboratory is a significant milestone in managing Jersey’s testing requirements." [ 7 ]
This biotechnology article is a stub . You can help Wikipedia by expanding it .
This article about an English company is a stub . You can help Wikipedia by expanding it .
This article about a service company in the United Kingdom is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OpenCell |
OpenCelliD is a collaborative community project that collects GPS positions of cell towers and their corresponding location area identity .
More than 49,000 contributors are registered with OpenCelliD, contributing more than 1 million new measurements every day on average to the OpenCelliD database. As of August 21, 2017 the database contained 35.5 million unique cells and 2.1 billion unique measurements. [ citation needed ]
OpenCelliD publishes an aggregate data set of cell locations licensed under a Creative Commons Attribution-ShareAlike 4.0 International License with the intention of promoting free use and redistribution of the data.
Data on Cell IDs and their locations can be used to provide location information to mobile devices. Using Cell ID locations to find device location is more power efficient and often faster [ 1 ] than using satellite-based navigation systems , although it is less precise because of the lack of known Cell IDs. [ 2 ] The database is also used to determine the strength of available wireless connections and which mobile phone service providers have coverage in specific geographic locations. [ citation needed ]
The unique location area identities of the cell towers can be collected by devices that utilize the wireless network provided by those cell towers. [ 3 ] This data is primarily contributed by smartphone users who have installed apps , such as OpenCelliD [ 4 ] or OpenCelliD Client, [ 5 ] and commercial tracking devices such as blackboxes, but also by wholesale data donation by corporations. This is then collected and transferred into the OpenCelliD API database. [ 6 ]
The OpenCelliD database is published under a Creative Commons Attribution-ShareAlike 4.0 International License open content license with the intention of promoting free use and redistribution of the data. | https://en.wikipedia.org/wiki/OpenCellID |
OpenChrom is an open source software for the analysis and visualization of mass spectrometric and chromatographic data. [ 4 ] Its focus is to handle native data files from several mass spectrometry systems (e.g. GC/MS, LC/MS, Py-GC/MS, HPLC-MS), vendors like Agilent Technologies , Varian , Shimadzu , Thermo Fisher , PerkinElmer and others. But also data formats from other detector types are supported recently.
OpenChrom supports only the analysis and representation of chromatographic and mass spectrometric data. It has no capabilities for data acquisition or control of vendor hardware. OpenChrom is built on the Eclipse Rich Client Platform (RCP), hence it is available for various operating systems, e.g. Microsoft Windows , macOS and Linux . It is distributed under the Eclipse Public License 1.0 (EPL). Third-party libraries are separated into single bundles and are released under various OSI compatible licenses.
OpenChrom was developed by Philip Wenig as part of his PhD thesis at the University of Hamburg , Germany. [ 5 ] The focus of the thesis was to apply pattern recognition techniques on datasets recorded by analytical pyrolysis coupled with chromatography and mass spectrometry (Py-GC/MS). [ 6 ] [ 7 ]
OpenChrom won the Thomas Krenn Open Source Award 2010 [ 8 ] as well as the Eclipse Community Award 2011. [ 9 ] The developers are also founding members of the Eclipse Science Working Group. [ 10 ] After successful commercialization of contract development and services around the OpenChrom project, vendor Lablicate reinforced the commitment to Free/Libre/Open-Source Software with the release of ChemClipse in October 2016, which serves as the base for all OpenChrom products. [ 11 ]
Each system vendor stores the recorded analysis data in its own proprietary format . That makes it difficult to compare data sets from different systems and vendors. Furthermore, it's a big drawback for interlaboratory tests. The aim of OpenChrom is to support a wide range of different mass spectrometry data formats natively. [ 12 ] OpenChrom takes care that the raw data files can't be modified according to the good laboratory practice . To help scientists OpenChrom supports several open formats to import and export the analysis results. In addition, OpenChrom offers its own open source format (*.ocb) that makes it possible to save the edited chromatogram as well as the peaks and identification results.
OpenChrom offers a variety of features to analyze chromatographic data:
The software was first released in 2010. Each release is named after a famous scientist. | https://en.wikipedia.org/wiki/OpenChrom |
This article describes the technical specifications of the OpenDocument office document standard , as developed by the OASIS industry consortium. A variety of organizations developed the standard publicly and make it publicly accessible, meaning it can be implemented by anyone without restriction. The OpenDocument format aims to provide an open alternative to proprietary document formats.
The OpenDocument format supports the following two ways of document representation:
The recommended filename extensions and MIME types are included in the official standard (OASIS, May 1, 2005, and its later revisions or versions). The MIME types and extensions contained in the ODF specification are applicable only to office documents that are contained in a package. Office documents that conform to the OpenDocument specification but are not contained in a package should use the MIME type text/xml.
The MIME type is also used in the office:mimetype attribute. It is very important to use this attribute in flat XML files/single XML documents, where this is the only way the type of the document can be detected (in a package, the MIME type is also present in a separate file mimetype ). Its values are the MIME types that are used for the packaged variant of office documents.
The most common file extensions used for OpenDocument documents are .odt for text documents, .ods for spreadsheets, .odp for presentation programs, and .odg for graphics. These are easily remembered by considering ".od" as being short for "OpenDocument", and then noting that the last letter indicates its more specific type (such as t for text).
Here is the complete list of document types, showing the type of file, the recommended file extension, and the MIME Type:
OpenDocument also supports a set of template types. Templates represent formatting information (including styles) for documents, without
the content themselves. The recommended filename extension begins with ".ot" (interpretable as short for "OpenDocument template"), with the last letter indicating what kind of template (such as "t" for text). The supported set includes:
As noted above, the OpenDocument format can describe text documents (for example, those typically edited by a word processor), spreadsheets, presentations, drawings/graphics, images, charts, mathematical formulas, and "master documents" (which can combine them). It can also represent templates for many of them.
The official OpenDocument standard version 1.0 (OASIS, May 1, 2005) defines OpenDocument's capabilities. The text below provides a brief summary of the format's capabilities.
The OpenDocument format supports storing metadata (data about the data) by having a set of pre-defined
metadata elements, as well as allowing user-defined and custom metadata.
The format predefines the following metadata fields:
OpenDocument's text content format supports both typical and advanced capabilities. Headings of various levels, lists of various kinds (numbered and not), numbered paragraphs,
and change tracking are all supported. Page sequences and section attributes can be used to control how the text is displayed. Hyperlinks, ruby text (which provides annotations and is especially critical for some languages), bookmarks, and references are supported as well. Text fields (for autogenerated content), and mechanisms for automatically generating
tables such as tables of contents, indexes, and bibliographies, are included as well.
The OpenDocument format implements spreadsheets as sets of tables. Thus it features extensive capabilities for formatting the display of tables and spreadsheets. OpenDocument also supports database ranges, filters, and "data pilots" (known in Microsoft Excel contexts as " pivot tables "). Change tracking is available for spreadsheets as well.
The graphics format supports a vector graphic representation, in which a set of layers and the contents [1] of each layer is defined. Available drawing shapes include Rectangle, Line, Polyline, Polygon, Regular Polygon, Path, Circle, Ellipse, and Connector. 3D Shapes are also available; the format includes information about the Scene, Light, Cube, Sphere, Extrude, and Rotate (it is intended for use as for office data exchange, and not sufficient to represent videos or other extensive 3D scenes). Custom shapes can also be defined.
Presentations are supported. Users can include animations in presentations, with control over the sound, showing a shape or text, hiding a shape or text, or dimming something, and these can be grouped. In OpenDocument, much of the format capabilities are reused from the text format, simplifying implementations. However, tables are not supported within OpenDocument as drawing objects, so may only be included in presentations as embedded tables.
Charts define how to create graphical displays from numerical data. They support titles, subtitles, a footer, and a legend to explain the chart. The format defines the series of data that is to be used for the graphical display, and a number of different kinds of graphical displays (such as line charts, pie charts, and so on).
Forms are specially supported, building on the existing XForms standard.
A document in OpenDocument format can contain two types of objects, as follows:
Use of Microsoft Object Linking and Embedding (OLE) objects limits the interoperability, because these objects are not widely supported in programs for viewing or editing files (e.g. embedding of other files inside the file, such as tables or charts from a spreadsheet application in a text document or presentation file). [ 5 ] [ 6 ] [ 7 ] [ 8 ] [ 9 ] If a software that understands an OLE object is not available, the object is usually replaced by a picture (bitmap representation of the object) or not displayed at all. [ 10 ] [ 11 ] [ 12 ]
The style and formatting controls are numerous, providing a number of controls over the display of information.
Page layout is controlled by a variety of attributes. These include page size, number format, paper tray, print orientation, margins, border (and its line width), padding, shadow, background, columns, print page order, first page number, scale, table centering, maximum footnote height and separator, and many layout grid properties.
Headers and footer can have defined fixed and minimum heights, margins, border line width, padding, background, shadow, and dynamic spacing.
There are many attributes for specific text, paragraphs, ruby text , sections, tables, columns, lists, and fills. Specific characters can have their fonts, sizes, generic font family names ( roman – serif , swiss – sans-serif , modern – monospace , decorative , script or system ), and other properties set. Paragraphs can have their vertical space controlled through attributes on keep together, widow, and orphan, and have other attributes such as "drop caps" to provide special formatting.
The list is extremely extensive; see the references (in particular the actual standard) for details.
OpenDocument version 1.2 fully describes mathematical formulas displayable on-screen. It is fully capable of exchanging spreadsheet data, formats, pivot tables , and other information typically included in a spreadsheet. OpenDocument exchanges formulas as values of the attribute table:formula.
The allowed syntax of table:formula was not defined in sufficient detail in the OpenDocument version 1.0 specification, which defined spreadsheet formulas using a set of simple examples showing, for example, how to specify ranges and the SUM() function. The OASIS OpenDocument Formula sub group therefore standardized the table:formula in the OpenFormula specification. For more information see the OpenFormula article.
When an OpenDocument file is password protected the file structure of the bundle remains the same, but contents of XML files in the package are encrypted using the following algorithm:
An OpenDocument file commonly consists of a standard ZIP archive ( JAR archive [ 13 ] ) containing a number of files and directories; but OpenDocument file can also consist only of a single XML document. An OpenDocument file is commonly a collection of several subdocuments within a (ZIP) package . An OpenDocument file as a single XML is not widely used.
According to the OpenDocument 1.0 specification, the ZIP file specification is defined in Info-ZIP Application Note 970311, 1997 . [ 14 ] [ 15 ] The simple compression mechanism used for a package normally makes OpenDocument files significantly smaller than equivalent Microsoft " .doc " or " .ppt " files. This smaller size is important for organizations who store a vast number of documents for long periods of time, and to those organizations who must exchange documents over low bandwidth connections. Once uncompressed, most data is contained in simple text-based XML files, so the uncompressed data contents have the typical ease of modification and processing of XML files. The standard also allows for the creation of a single XML document, which uses <office:document> as the root element, for use in document processing.
The standard allows the inclusion of directories to store images, non- SMIL animations, and other files that are used by the document but cannot be expressed directly in the XML.
Due to the openly specified compression format used, it is possible for a user to extract the container file to manually edit the contained files. This allows repair of a corrupted file or low-level manipulation of the contents.
The zipped set of files and directories includes the following:
The OpenDocument format provides a strong separation between content, layout and metadata. The most notable components of the format are described in the subsections below. The files in XML format are further defined using the RELAX NG language for defining XML schemas. RELAX NG is itself defined by an OASIS specification, as well as by part two of the international standard ISO/IEC 19757: Document Schema Definition Languages (DSDL).
content.xml , the most important file, carries the actual content of the document (except for binary data, such as images). The base format is inspired by HTML, and though far more complex, it should be reasonably legible to humans:
styles.xml contains style information. OpenDocument makes heavy use of styles for formatting and layout. Most of the style information is here (though some is in content.xml). Styles types include:
The OpenDocument format is somewhat unusual in that using styles for formatting cannot be avoided. Even "manual" formatting is implemented through styles (the application dynamically makes new styles as needed).
meta.xml contains the file metadata. For example, Author, "Last modified by", date of last modification, etc. The contents look somewhat like this:
The names of the <dc:...> tags come from the Dublin Core XML standard.
settings.xml includes settings such as the zoom factor or the cursor position. These are properties that are not content or layout.
mimetype is just a one-line file with the mimetype of the document. One implication of this is that the file extension is actually immaterial to the format. The file extension is only there for the benefit of the user. It is important to note that this special file is always the first file entry in the ZIP archive and it is uncompressed. Because the ZIP header uses fields with fixed lengths, this allows the direct identification of the different OpenDocument formats without decompression of the content (e. g. with magic bytes).
Thumbnails is a separate folder for a document thumbnail. The thumbnail must be saved as “thumbnail.png”. A thumbnail representation of a document should be generated by default when the file is saved. It should be a representation of the first page, first sheet, etc. of the document. The required size for the thumbnails is 128x128 pixel. In order to conform to the Thumbnail Managing Standard (TMS) at www.freedesktop.org, thumbnails must be saved as 8bit, non-interlaced PNG image with full alpha transparency.
META-INF is a separate folder. Information about the files contained in the OpenDocument package is stored in an XML file called the manifest file. The manifest file is always stored at the pathname META-INF/manifest.xml. The main pieces of information stored in the manifest are:
Pictures is a separate folder for images included in the document. This folder is not defined in the OpenDocument specification. Files in this folder can use various image formats, depending on the format of inserted file. While the image data may have an arbitrary format, it is recommended that bitmap graphics are stored in the PNG format and vector graphics in the SVG format.
By design, OpenDocument reuses existing open XML standards whenever they are available, and it creates new tags only where no existing standard can provide the needed functionality. Thus OpenDocument uses a subset of DublinCore for metadata , MathML for displayed formulas , SMIL for multimedia , XLink for hyperlinks etc.
Although not fully reusing SVG for vector graphics , OpenDocument does use SVG-compatible vector graphics within an ODF-format-specific namespace, but also includes non-SVG graphics.
To indicate which version of the OpenDocument specification a file complies with, all root elements take an office:version attribute (in the format revision.version , such as office:version="1.1" ), which identifies the version of ODF specification that defined the associated element, its schema, its complete content, and its interpretation.
It is not mandatory to use office:version attribute in ODF 1.0 and ODF 1.1 files, so when an element has office:version omitted, the element is based on ODF 1.0 or 1.1. If the file has a version known to an XML processor, it may validate the document. Otherwise, it is optional to validate the document, but the document must be well formed.
The office:version attribute shall be present in each and every <office:document>, <office:document-content>, <office:document-styles>, <office:document-meta>, and <office:document-settings> element in the XML documents that comprise an OpenDocument 1.2 or newer document. The value of the office:version attribute shall reflect the OpenDocument version. [ 20 ]
The OpenDocument specification does not specify which elements and attributes conforming applications must, should, or may support. Even typical office applications may only support a subset of the elements and attributes defined in the specification. The specification contains a non-normative table that provides an overview which element and attributes usually are supported by
typical office application.
Documents that conform to the OpenDocument specification may contain elements and attributes not specified within the OpenDocument schema. Such elements and attributes must not be part of a namespace that is defined within the specification and are called foreign elements and attributes.
Conforming applications either shall read documents that are valid against the OpenDocument schema if all foreign elements and attributes are removed before validation takes place, or shall write documents that are valid against the OpenDocument schema if all foreign elements and attributes are removed before validation takes place.
Conforming applications that read and write documents may preserve foreign elements and attributes. In addition to this, conforming applications should preserve meta information and the content of styles.
Conforming applications shall read documents containing processing instructions and should preserve them.
ODF 1.2 defines precisely the conformance needs. The specification defines conformance for documents, consumers, and producers, with two conformance classes called conforming and extended conforming. It further defines conforming text, spreadsheet, drawing, presentation, chart, image, formula and database front end documents. Chapter 2 defines the basic requirements for the individual conformance targets. [ 21 ] | https://en.wikipedia.org/wiki/OpenDocument_technical_specification |
OpenFOAM ( Open Field Operation And Manipulation ) [ 8 ] is a C++ toolbox for the development of customized numerical solvers , and pre-/post-processing utilities for the solution of continuum mechanics problems, most prominently including computational fluid dynamics (CFD).
The OpenFOAM software is used in research organisations, academic institutes and across many types of industries, for example, automotive , manufacturing , process engineering , environmental engineering and marine energy . [ 9 ]
OpenFOAM is open-source software which is freely available and licensed under the GNU General Public License Version 3, with the following variants:
The name FOAM has been claimed to appear for the first time as a post-processing tool written by Charlie Hill, in the early 90s in Prof. David Gosman 's group in Imperial College London . [ citation needed ] As a counter argument [ verification needed ] , it has been claimed that Henry Weller created the FOAM library for field operation and manipulation which interfaced to the GUISE (Graphical User Interface Software Environment) which was created by Charlie Hill for interfacing to AVS .
As a continuum mechanics / computational fluid dynamics tool, the first development of FOAM (which became OpenFOAM later on) was virtually always presumed to be initiated by Henry Weller at the same institute by using the C++ programming language rather than the de facto standard programming language FORTRAN of the time to develop a powerful and flexible general simulation platform. From this initiation to the founding of a company called Nabla Ltd, (predominantly) Henry Weller and Hrvoje Jasak carried out the basic development of the software for almost a decade. [ 11 ] For a few years, FOAM was sold as a commercial code by Nabla Ltd., [ 12 ] on 10 December 2004, it was released under GPL and renamed to OpenFOAM. [ 5 ]
In 2004, Nabla Ltd was folded. Immediately afterwards, Henry Weller, Chris Greenshields and Mattijs Janssens founded OpenCFD Ltd to develop and release OpenFOAM. [ 13 ] At the same time, Hrvoje Jasak founded the consulting company Wikki Ltd [ 14 ] and maintained a fork of OpenFOAM called openfoam-extend, later renamed to foam-extend .
In April 2008, the OpenFOAM development moved to using git for its source code repository. [ 15 ]
On 5 August 2011, OpenCFD transferred its copyrights and interests in OpenFOAM ( source code ) and documentation to the newly incorporated OpenFOAM Foundation Inc., registered in the state of Delaware, USA. [ 16 ]
On 8 August 2011, OpenCFD was acquired by Silicon Graphics International (SGI). [ 17 ] On 12 September 2012, ESI Group announced the acquisition of OpenCFD Ltd, [ 18 ] becoming a wholly-owned subsidiary of ESI Group, and OpenCFD retaining its ownership of the OpenFOAM trademark.
On 25 April 2014, The OpenFOAM Foundation Ltd was incorporated in England, as a company limited by guarantee with all assets transferred to the UK and the US entity dissolved, together with changes to the governance of the Foundation. Weller and Greenshields left OpenCFD and formed CFD Direct Ltd in March 2015. [ 19 ]
On 3 September 2024, Cristel de Rouvray, CEO of ESI Group officially resigned as Founder Member and director of The OpenFOAM Foundation Limited.
The OpenFOAM Foundation Ltd directors are Henry Weller, Chris Greenshields, and Brendan Bouffler.
The following are the three main variants of OpenFOAM:
In 2018, OpenCFD Ltd. and some of its industrial, academic, and community partners established an administrative body, i.e. OpenFOAM Governance , to allow the OpenFOAM's user community to decide/contribute the future development and direction of their variant of the software. [ 22 ]
The structure of OpenFOAM Governance consisted of a Steering Committee and various Technical Committees . The Steering Committee comprised representatives from the main sponsors of OpenFOAM in industry, academia, release authorities and consultant organisations. The organisation composition of the initial committee involved members from OpenCFD Ltd., ESI Group , Volkswagen , General Motors , FM Global , TotalSim Ltd., TU Darmstadt , and Wikki Ltd. [ 23 ]
In addition, nine technical committees were established in the following areas: Documentation, high performance computing , meshing , multiphase , numerics , optimisation , turbulence , marine applications, and nuclear applications with the members from the organisations of OpenCFD Ltd., CINECA , University of Zagreb , TU Darmstadt , National Technical University of Athens , Upstream CFD GmbH, University of Michigan , and EPFL . [ 24 ]
The OpenFOAM directory structure consists of two main directories:
OpenFOAM computer simulations are configured by several plain text input files located across the following three directories: [ 25 ]
Additional directories can be generated, depending on user selections. These may include: | https://en.wikipedia.org/wiki/OpenFOAM |
open Home Automation Bus ( openHAB ) is an open source home automation software written in Java . It is deployed on premises and connects to devices and services from different vendors. As of 2019, close to 300 bindings are available as OSGi modules. [ 2 ] Actions, such as switching on lights, are triggered by rules, voice commands, or controls on the openHAB user interface.
The openHAB project started in 2010. In 2013, the core functionality became an official project of the Eclipse Foundation under the name Eclipse SmartHome. [ 3 ] openHAB is based on Eclipse SmartHome and remains the project for the development of bindings.
According to Black Duck Open Hub , it is developed by one of the largest open-source teams in the world. [ 4 ] It also has an active user community. [ 5 ]
OpenHAB requires a JVM and can be deployed on servers running various operating systems, a dedicated Raspberry Pi instance, or some network-attached storage systems. [ 6 ] [ 7 ] The required bindings can be added at runtime via OSGi. OpenHAB supports a number of persistence backends for storing and querying the smart home data, including relational and time series databases. By default openHAB uses rrd4j for persistence. [ 8 ]
After installation, openHAB scans the local network and discovers devices that can be included in the smart home solution. [ 9 ] Users can provide credentials and meaningful device names via an administration user interface.
Since major version 2 of openHAB the connections to physical devices is split in 2 levels. "Things" are the interface elements to a specific physical device (e.g. an interface to a home automation network like KNX , Z-Wave or Zigbee ). Within these things, one or more "Items" can then be defined or discovered. These "Items" correspond to one specific component like a relay controlling a light, the desired temperature of a heating system or a dimmer percentage.
Sitemaps allow the user to determine how the devices in the smart home are arranged. A sitemap groups devices by floor and room and determines how they are visualized and controlled. The following example illustrates what a typical sitemap definition might look like:
Once the system is configured, openHAB users can view data and perform actions using a number of user interfaces. These include a browser based interface as well as apps for Android , Windows 10 , and iOS . [ 10 ] [ 11 ] [ 12 ] All of these UIs are defined by the sitemap mechanism.
An event, condition, action rule-based system is used to automate the smart home. The following example turns off a light once the sun rises at the configured location.
OpenHAB Cloud is a companion cloud service and backend for openHAB. It provides secure remote access and enables openHAB users to remotely monitor, control and steer their homes through the internet. The openHAB foundation provides a demo system without SLA guarantees. [ 13 ]
In 2020, the code was forked for a major rework, separating to 2.5 version from the upcoming 3.0 branch. [ 14 ] Apart from some technical code changes (e.g. use of Java 11 ), several functional improvements are foreseen:
The main drawback is that backward compatibility to openHAB add-ons for version 1 is dropped.
Version 3.0 has been released as of 21 December 2020. [ 15 ]
Many security and privacy concerns have been raised with home automation and IoT in general. OpenHAB's on-premises engine and open source character are answers to these concerns. [ 16 ] However, it was criticized for its use of default configurations. [ 17 ]
OpenHAB won the IoT Challenge 2013 [ 18 ] and the JavaOne Duke's Choice Award 2013. [ 19 ] It was nominated for the JAX Innovation Award 2014 [ 20 ] and was the People's Choice Winner at the Postscapes IoT Awards 2014/15. [ 21 ] | https://en.wikipedia.org/wiki/OpenHAB |
The OpenHAN standards for home networks (sometimes called home grids) was promoted by groups such as openAMI ( Advanced Metering Infrastructure ) [ 1 ] and UtilityAMI. [ 2 ] Both efforts aim to standardize powerline networking interoperation from a utility point of view and ensure reliable communications co-extant with AC power outlets.
Both utilities and vendors of home control have promoted such standards aggressively . [ 3 ] The openHAN label usually denotes standards favored by the utilities, not other service providers. It should be distinguished from the openADR standards that were promoted to ensure open access to customer electricity use data by all service providers.
A major rationale for a single set of standards is for the utilities themselves to provide a unified home energy monitor that "provides prompt, convenient feedback on electrical or other energy use. Devices may also display cost of energy used, and estimates of greenhouse gas emissions. Various studies have shown a reduction in home energy use of 4-15% through use of home energy display. Electricity use may be measured with an inductive clamp placed around the electric main, via the electric meter (either through an optical port, or by sensing the meters actions), by communicating with a smart meter, or by direct connection to the electrical system." [ 4 ] Such reductions are contingent on every smart appliance reporting to a single central monitor.
In the US, the National Broadband Plan emphasized (in its "goal 6") that consumers must be able to share usage data with literally any service provider, not just their electric distributor, who must then be able to provide simple instructions or direct remote control of the consumer's residential appliances and home grid.
Utilities accordingly have been motivated to remain ahead of the technology curve and aggressively roll out these capabilities internally. "With increasing investments in smart meters and the smart grid, these systems have the capability of integrating AMI/MDM data from multiple vendor sources. Progress reports can be provided online and by mail, and outbound messaging can be Web-based and/or SMS text-based for maximum reach. When integrated with the billing process for either print or online presentment, the utility can communicate to the customer valuable information to increase the understanding of energy use, its drivers, how to save, and comparisons to standards in their area." [ 4 ]
Perhaps reflecting utility influence, OpenHAN was one of the original NIST smart grid standards sanctioned for by the North American Electric Reliability Corporation (NERC). Unlike most other networking standards, it uses in-home wiring between AC-powered devices. It primarily relies on AC powerline networking as defined by IEEE 1901 and packet management under ITU G.hn . The closest DC equivalent is power over Ethernet (PoE). These [ which? ] are used for smart thermostats and other smart appliances , put power and data all on one wire, and similarly have about one gigabit capacity. Unlike PoE which requires cat5 or cat6 Ethernet wiring redundant with the AC wiring, OpenHAN makes use of all existing wire (AC outlets, cable coax and telephone cat3). [ 4 ] [ 5 ]
In the OpenHAN architecture, "The display portion is remote from the measurement, communicating with the sensor using a cable, power-line communications , or using radio. Online displays are also available which allow the user to display near real-time consumption on any device that can connect to the Internet. These displays can reduce household energy consumption by providing real-time feedback to homeowners so they can change their energy using behavior. A study using the PowerCost Monitor deployed in 500 Ontario homes by Hydro One showed an average 6.5% drop in total electricity use when compared with a similarly sized control group. Hydro One subsequently offered free power monitors to 30,000 customers based on the success of the pilot. Blue Line Innovations also indicates 100,000 units in the market today." [ 4 ] Other customer relationship management tactics can be used to reinforce and encourage reduction of energy use, including using direct outbound messages.
According to the utilities involved, all smart appliances and smart meters (which also must meet openADR standards for energy demand management ) must meet the OpenHAN standard. Its appliance interface connector [ 6 ] is meant to ensure that all openHAN devices can communicate with each other. The energy services interface [ 3 ] defines how energy use is managed. Implementing companies include Synapse, the Zigbee and HomePlug consortia, Trilliant , United Illuminating , Ingersoll-Rand and others closely affiliated with the utilities and seeking to sell them more equipment.
A task force of the Open Smart Grid Users Group published a systems requirement specification in 2008, which was revised in August 2010. [ 7 ] | https://en.wikipedia.org/wiki/OpenHAN |
OpenJMS is one of the major providers of Java Message Service API, which implements Sun Microsystems ' Java Message Service API 1.1 Specification. The current release is OpenJMS 0.7.7-beta-1.
Java Message Service is an asynchronous communication mechanism in the distributed system field. It is very helpful in the situation where the distributed components are loosely coupled. Another popular distributed communication technology is Remote Method Invocation (RMI), which is tightly coupled and requires an application to know a remote application's methods.
One benefit of OpenJMS is that it is vendor neutral. Because the Java JMS specifications do not specify a wire protocol, each vendor's JMS implementation is distinct and not interoperable with others. Since JMS's are normally released as part of an application server provider this makes the implementation of a JMS vendor specific to that application server. OpenJMS is not dependent on any given application server and therefore can be a common interface between users of different vendors. Users of various application servers can agree to use the common OpenJMS implementation for their interoperability layers.
This computing article is a stub . You can help Wikipedia by expanding it . | https://en.wikipedia.org/wiki/OpenJMS |
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