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2,252,775 | https://en.wikipedia.org/wiki/Air-cooled%20engine | Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. Air-cooled designs are far simpler than their liquid-cooled counterparts, which require a separate radiator, coolant reservoir, piping and pumps.
Air-cooled engines are widely seen in applications where weight or simplicity is the primary goal. Their simplicity makes them suited for uses in small applications like chainsaws and lawn mowers, as well as small generators and similar roles. These qualities also make them highly suitable for aviation use, where they are widely used in general aviation aircraft and as auxiliary power units on larger aircraft. Their simplicity, in particular, also makes them common on motorcycles.
[[Image:newjug1.jpg|justify|thumb|010(9_29743dfqrto apos)
Introduction
Most modern internal combustion engines are cooled by a closed circuit carrying liquid coolant through channels in the engine block and cylinder head. A fluid in these channels absorbs heat and then flows to a heat exchanger or radiator where the coolant releases heat into the air (or raw water, in the case of marine engines). Thus, while they are not ultimately cooled by the liquid, as the heat is exchanged with some other fluid like air, because of the liquid-coolant circuit they are known as liquid-cooled.
In contrast, heat generated by an air-cooled engine is released directly into the air. Typically this is facilitated with metal fins covering the outside of the Cylinder Head and cylinders which increase the surface area that air can act on. Air may be force fed with the use of a fan and shroud to achieve efficient cooling with high volumes of air or simply by natural air flow with well designed and angled fins.
In all combustion engines, a great percentage of the heat generated, around 44%, escapes through the exhaust. Another 8% or so ends up in the oil, which itself has to be cooled in an oil cooler. This means less than half of the heat has to be removed through other systems. In an air-cooled engine, only about 12% of the heat flows out through the metal fins. Air cooled engines usually run noisier, however it provides more simplicity which gives benefits when it comes to servicing and part replacement and is usually cheaper to be maintained.
Applications
Road vehicles
Many motorcycles use air cooling for the sake of reducing weight and complexity. Few current production automobiles have air-cooled engines (such as Tatra 815), but historically it was common for many high-volume vehicles. The orientation of the engine cylinders is commonly found in either single-cylinder or coupled in groups of two, and cylinders are commonly oriented in a horizontal fashion as a Flat engine, while vertical Straight-four engine have been used. Examples of past air-cooled road vehicles, in roughly chronological order, include:
Franklin (1902-1934)
New Way (1905) - limited production run out from the "CLARKMOBILE"
Chevrolet Series M Copper-Cooled (1921-1923) (very few built)
Tatra all-wheel-drive military trucks
Tatra 11 (1923-1927) and subsequent models
Tatra T77 (1934-1938)
Tatra T87 (1936-1950)
Tatra T97 (1936-1939)
Tatra T600 Tatraplan (1946-1952)
Tatra T603 (1955-1975)
Tatra T613 (1974-1996)
Tatra T700 (1996-1999)
Crosley (1939-1945)
The East German Trabant (1957-1991)
Trabant 500 (1957-1962)
Trabant 600 (1962-1965)
Trabant 601 (1964-1989)
ZAZ Zaporozhets (1958-1994)
Fiat 500 (1957-1975)
Fiat 126 (1972-1987)
Porsche 356 (1948-1965)
Porsche 911 (1964-1998)
Porsche 912 (1965-1969, 1976)
VW-Porsche 914 (1969-1976)
The Volkswagen Beetle, Type 2, SP2, Karmann Ghia, and Type 3 all utilized the same air-cooled engine (1938-2013) with various displacements
Volkswagen Type 2 (T3) (1979–1982)
Volkswagen Type 4 (1968-1974)
Volkswagen Gol (G1) (1980-1986)
Toyota U engine (1961-1976)
Chevrolet Corvair (1960-1969)
Citroën 2CV (1948-1990) (Featured a high pressure oil cooling system, and used a fan bolted to the crankshaft end)
Citroën GS and GSA
Honda 1300 (1969-1973)
NSU Prinz
Royal Enfield Motorcycles (India): The 350cc and 500cc Twinspark motorcycle engines are air-cooled
Oltcit Club (1981–1995)T13/653, G11/631 and VO36/630
Demak Dzm 200 2015
Aviation
During the 1920s and 30s there was a great debate in the aviation industry about the merits of air-cooled vs. liquid-cooled designs. At the beginning of this period, the liquid used for cooling was water at ambient pressure. The amount of heat carried away by a fluid is a function of its capacity and the difference in input and output temperatures. As the boiling point of water is reduced with lower pressure, and the water could not be efficiently pumped as steam, radiators had to have enough cooling power to account for the loss in cooling power as the aircraft climbed. The resulting radiators were quite large and caused a significant amount of aerodynamic drag.
This placed the two designs roughly equal in terms of power to drag, but the air-cooled designs were almost always lighter and simpler. In 1921, the US Navy, largely due to the efforts of Commander Bruce G. Leighton, decided that the simplicity of the air-cooled design would result in less maintenance workload, which was paramount given the limited working area of aircraft carriers. Leighton's efforts led to the Navy underwriting air-cooled engine development at Pratt & Whitney and Wright Aeronautical.
Most other groups, especially in Europe where aircraft performance was rapidly improving, were more concerned with the issue of drag. While air-cooled designs were common on light aircraft and trainers, as well as some transport aircraft and bombers, liquid-cooled designs remained much more common for fighters and high-performance bombers. The drag issue was upset by the 1929 introduction of the NACA cowl, which greatly reduced the drag of air-cooled engines in spite of their larger frontal area, and the drag related to cooling was at this point largely even.
In the late 1920s into the 1930s, a number of European companies introduced cooling system that kept the water under pressure allowed it to reach much higher temperatures without boiling, carrying away more heat and thus reducing the volume of water required and the size of the radiator by as much as 30%, which opened the way to a new generation of high-powered, relatively low-drag liquid cooled inline engines such as the Rolls-Royce Merlin and Daimler-Benz DB601, which had an advantage over the unpressurized early versions of the Jumo 211. This also led to development work attempting to eliminate the radiator entirely using evaporative cooling, allowing it to turn to steam and running the steam through tubes located just under the skin of the wings and fuselage, where the fast moving outside air condensed it back to water. While this concept was used on a number of record-setting aircraft in the late 1930s, it always proved impractical for production aircraft for a wide variety of reasons.
In 1929, Curtiss began experiments replacing water with ethylene glycol in a Curtiss D-12 engine. Glycol could run up to 250 C and reduced the radiator size by 50% compared to water cooled designs. The experiments were extremely successful and by 1932 the company had switched all future designs to this coolant. At the time, Union Carbide held a monopoly on the industrial process to make glycol, so it was initially used only in the US, with Allison Engines picking it up soon after. It was not until the mid-1930s that Rolls-Royce adopted it as supplies improved, converting all of their engines to glycol. With the much smaller radiators and less fluid in the system, the weight and drag of these designs was well below contemporary air-cooled designs. On a weight basis, these liquid-cooled designs offered as much as 30% better performance.
In the late- and post-war era, the high-performance field quickly moved to jet engines. This took away the primary market for late-model liquid-cooled engines. Those roles that remained with piston power were mostly slower designs and civilian aircraft. In these roles, the simplicity and reduction in servicing needs is far more important than drag, and from the end of the war on almost all piston aviation engines have been air-cooled, with few exceptions.
, most of the engines manufactured by Lycoming and Continental are used by major manufacturers of light aircraft Cirrus, Cessna and so on. Other engine manufactures using air-cooled engine technology are ULPower and Jabiru, more active in the Light-Sport Aircraft (LSA) and ultralight aircraft market. Rotax uses a combination of air-cooled cylinders and liquid-cooled cylinder heads.
Diesel engines
Some small diesel engines, e.g. those made by Deutz AG and Lister Petter are air-cooled. Probably the only big Euro 5 truck air-cooled engine (V8 320 kW power 2100 N·m torque one) is being produced by Tatra. BOMAG part of the FAYAT group also utilizes an air cooled inline 6 cylinder motor, in many of their construction vehicles.
Stationary or portable engines
Stationary or portable engines were commercially introduced early in the 1900s. The first commercial production was by the New Way Motor Company of Lansing, Michigan, US. The company produced air-cooled engines in single and twin cylinders in both horizontal and vertical cylinder format. Subsequent to their initial production which was exported worldwide, other companies took up the advantages of this cooling method, especially in small portable engines. Applications include mowers, generators, outboard motors, pump sets, saw benches and auxiliary power plants and more.
References
Bibliography
Cited sources
Further reading
P V Lamarque, "The design of cooling fins for Motor-Cycle Engines". Report of the Automobile Research Committee, Institution of Automobile Engineers Magazine, March 1943 issue, and also in "The Institution of Automobile Engineers. Proceedings XXXVII, Session 1942-1943, pp 99-134 and 309-312.
Julius Mackerle, "Air-cooled Automotive Engines", Charles Griffin & Company Ltd., London 1972.
Engines | Air-cooled engine | [
"Physics",
"Technology"
] | 2,210 | [
"Physical systems",
"Machines",
"Engines"
] |
2,252,832 | https://en.wikipedia.org/wiki/PersonalJava | PersonalJava was a Java edition for mobile and embedded systems based on Java 1.1.8. It has been superseded by the CDC's Personal Profile, which is not widely deployed.
References
External links
PersonalJava Application Environment
Java device platform | PersonalJava | [
"Technology"
] | 52 | [
"Mobile computer stubs",
"Mobile technology stubs"
] |
2,252,847 | https://en.wikipedia.org/wiki/Ammonia%20%28data%20page%29 | This page provides supplementary chemical data on ammonia.
Structure and properties
Thermodynamic properties
Vapor–liquid equilibrium data
Table data (above) obtained from CRC Handbook of Chemistry and Physics 44th ed. The (s) notation indicates equilibrium temperature of vapor over solid. Otherwise temperature is equilibrium of vapor over liquid.
Vapor-pressure formula for ammonia:
log10P = A – B / (T − C),
where P is pressure in kPa, and T is temperature in kelvins;
A = 6.67956, B = 1002.711, C = 25.215 for T = 190 K through 333 K.
Heat capacity of liquid and vapor
Spectral data
Regulatory data
Safety data sheet
The handling of this chemical may incur notable safety precautions... It is highly recommend that you seek the Safety Data Sheet (SDS) for this chemical from a reliable source and follow its directions.
SIRI
Science Stuff (Ammonia Solution)
References
External links
Phase diagram for ammonia
IR spectrum (from NIST)
Chemical data pages
Chemical data pages cleanup | Ammonia (data page) | [
"Chemistry"
] | 214 | [
"Chemical data pages",
"nan"
] |
2,252,874 | https://en.wikipedia.org/wiki/Epidemiology%20of%20suicide | There are more than 720,000 estimated global suicide deaths every year. Suicide affects every demographic, yet there are some populations that are more impacted than others. For example, among 15–29 year olds, suicide is much more prominent; this being the third leading cause of death within this age group.
Suicide is a worldwide issue which is disproportionally affecting developed countries, with 23% of the total suicide rate despite having only 17% of global population.
There are many competing factors that come into play when determining the epidemiology of suicide such as biological sex, race and sexual orientation, religion, social determinants of health, and seasonal trends.
Overview
Suicide rates are actively increasing around the globe. It is an increasingly common idealization, with someone considering taking their own life every 40 seconds. From the years 2000–2021 suicide rates have gone up approximately 36%.
The cause of this increased risk of suicide can be attributed to multiple factors. While there is no single defined cause of suicide, there are three overarching themes when it comes to causation: health, environmental and historical factors.
Health causes could be related to mental health diagnosis such as depression, schizophrenia, anxiety disorders or traumatic brain injuries. Around 46% of suicide cases had previously been diagnosed with a mental health disorder. This is a fluctuating estimate due to the fact that mental health is often overlooked and under reported.
Environmental causes could be access to weapons or drugs, childhood stress or exposures to other abuses. Bullying is a common catalyst as it increases social isolation and self deprivation in the same prolonged instances. "According to studies by Yale University, victims of bullying are between 2 to 9 times more likely to consider suicide than non-victims."
Historical factors also play a role. Exposure to suicide in the developmental years can put an individual at increased risk of their own death. Many studies have been conducted to conclude that suicide contagion is a serious problem, especially for young people. Suicide can be facilitated in vulnerable teens by exposure to real or fictional accounts of suicide, including media coverage of suicide, such as intensive reporting of the suicide of a celebrity or idol.
Geography- Country
As of 2019, the highest annual number of suicides per 100,000 people was in Lesotho, with a rate of 87.5 deaths per 100,000 people. The second country being Guyana with 40.9 deaths per 100,000 people and third Eswatini, with 40.5 deaths per 100,000 people.
Low-income countries share the burden of suicidal persons due to their impoverished state which explains the top three countries on the suicide rate list.
In other parts of the world, suicide rates are not as extreme, but the issue of suicide is still extremely apparent.
About 21.6 suicide deaths per 100,000 people occur in Russia every year; in southern Africa, the average is about 21 deaths per 100,000 people. The United States reports about 14.5 deaths annually per 100,000 people, however, this rate is steadily increasing. In the 2000s, that rate was 10 people per 100,000 people per year. Within countries there is variety as well. As of 2021, Wyoming is the leading state in annual suicide with 32.3 deaths per 100,000 people. On the other hand, New Jersey, has the lowest suicide rate with 7.1 deaths per 100,000 people.
Rural and Urban suicide rates differ as well.
Sex
In the United States, males are four times more likely to die by suicide than females, although more women than men report suicide attempts and self-harm with suicidal intentions. Male suicide rates are far higher than females in all age groups (the ratio varies from 3:1 to 10:1). In other western countries, males are also much more likely to die by suicide than females (usually by a factor of 3–4:1). It was the 8th leading cause of death for males, and 19th leading cause of death for females.
Excess male mortality from suicide is generally lower in non-Western nations. In eight countries, including China with about one-fifth of the world population, the rate of male mortality from suicide is lower than that for females, with females more likely to die by suicide by a factor of 1.3–1.6
Age
Nearly half of all Suicides in the United States are accounted for in the age range of 35–64 years. Adults aged 75 and older are at increased risk of suicide rates (20.3 per 100,000). However suicide may be a lower percentage accounting for all suicides across the United States, in a subgroup of ages 10–24 it is the second leading cause of death.
Race and sexual orientation
Race
Research across the United States shows that across all age groups, Non-Hispanic Alaskan Natives and American Indians are at the highest risk of suicide. In years 2018–2021, suicide rates significantly increased within these populations.
In 2003 in the United States, Whites and Asians were nearly 2.5 times more likely to kill themselves than Blacks or Mexicans. In the eastern portion of the world (primarily in Asian and Pacific-Island countries), the numbers of reported suicides are growing every year.
Sexual Orientation
The likelihood of suicide attempts are increased in both gay males and lesbians, as well as bisexuals of both sexes when compared to their heterosexual counterparts. The trend of having a higher incident rate among females is no exception with lesbians or bisexual females, and when compared with homosexual males, lesbians are more likely to attempt suicide than gay or bisexual males.
Evidence varies between studies with how increased the risk of suicide in the queer community in comparison to heterosexuals. The lowest reported increases stated suicide is 0.8–1.1 times more likely for queer females and 1.5–2.5 times more likely for queer males. The highest increases reach 4.6 more likely in females and 14.6 more likely in males who do not identify as heterosexual.
Race and age also play a factor in the increased risk. The highest ratios for males are for Caucasians in their youth. By the age of 25, their risk is down to less than half of what it was However gay Black males' risk steadily increases to 8.6 times more likely in this same age group. Lifetime risks are 5.7 times more for White and 12.8 times more for Black gay and bisexual males.
In lesbian and bisexual females, age has opposite effect with fewer attempts in youth when compared to heterosexual females. Throughout their lifetime, the likelihood of LGBTQ+ females to attempt suicide nearly triples the youth ratio for Caucasian females, however for Black females, the rate is less significant (less than 0.1 to 0.3 difference) with heterosexual Black females having a slightly higher risk throughout most of the age-based study.
Gay and lesbian youth who attempt suicide are disproportionately subject to anti-gay attitudes, and have weaker skills for coping with discrimination, isolation, and loneliness. They were also more likely to experience family rejection than those who do not attempt suicide. Another study found that gay and bisexual youth who attempted suicide had a more feminine gender presentation, adopted an LGBTQ+ identity at a young age, and were more likely than their peers to report sexual abuse, drug abuse, and arrests for misconduct.
There is evidence that same-sex sexual behavior, but not homosexual attraction or homosexual identity, was significantly predictive of suicide among Norwegian adolescents. In Denmark, the age-adjusted suicide mortality risk for men in registered domestic partnerships was nearly eight times greater than for men with positive histories of heterosexual marriage, and nearly twice as high for men who had never married.
A large study of suicide in Sweden involved the analysis of data records for 6,456 same-sex married couples and 1,181,723 man-women marriages. The study showed that even with Sweden's tolerant attitude regarding homosexuality, it was determined that for same-sex married men, the suicide risk was nearly three times higher than for different-sex married men, even after an adjustment for HIV status. For women, it was shown that there was a tentatively elevated suicide risk for same-sex married women over that of different-sex married women.
Religion
Every major religion in the world is opposed to suicide. However, the stringency of this belief depends on the individual. Teachings within religions may vary and different individuals may interpret these teachings differently.
Suicide rates between different religions vary. Among the major religions in the US, Protestants have the highest rate of suicide. Roman Catholics had the next highest rate, followed by Jews and Muslims.
In most cases, religiosity has been associated with reduced risk of suicide. Collectively, individuals who reside in religious countries and are integrated into their religious community are less accepting of suicide Compared to secular countries, suicide rates are lower in countries with a state religion. A global study on atheism noted countries with higher levels of atheism had the highest suicide rates compared to countries with "statistically insignificant levels of organic atheism." The People's Republic of China, which is an atheist state, had the highest suicide rate (25.6 per 100,000 persons).
However, studies have been criticized for oversimplifying the relationship between religion and the risk of suicide, as this association can vary depending on culture. Religion may adversely affect mental health if there is discord between an individual's beliefs and their faith. In some cases, religion may be related to a higher risk of suicide if it leads a person to feel guilty, isolated, or abandoned by the community. Additionally, there is evidence to suggest that while religious affiliation protects against suicide attempts, it does not stop suicidal ideation.
Social, Political and Economic Factors
Higher levels of social and national cohesion reduce suicide rates. Suicide levels are highest among the retired, unemployed, impoverished, divorced, the childless, empty nesters, and other people who live alone. Suicide rates also rise during times of economic uncertainty. (Although poverty is not a direct cause, it can contribute to the risk of suicide).
Epidemiological studies generally show a relationship between suicide or suicidal behaviors and socio-economic disadvantage. Disadvantages include limited educational achievement, homelessness, unemployment, economic dependence, and contact with the police or justice system. It has been shown for individuals who suffer from unemployment, the longer they are unemployed, the greater the risk of suicide. Additionally, the lifetime prevalence of suicidal ideation in the homeless community was 41.60% while the lifetime prevalence of suicide attempt was 28.88%.
A 2015 UK study by the Office for National Statistics, commissioned by Public Health England, which considered 18,998 deaths of people aged between 20 and 64, found that the employment sectors with the highest incidence of suicide for men was construction, and for women culture, media and sport, healthcare, and primary school teaching.
Men working in the construction industry and women employed in culture, media and sport, healthcare and primary school teaching are at the highest risk of suicide, official figures for England suggest.
Certain political constructs can act as protective factors against suicide. The most apparent factor is an increase in minimum wage which precedes inflation. Other factors include social welfare expenditures, and laws which restrict access to firearms and alcohol.
Health
Mental Illness
Societally, mental disorders are highly associated with suicide risk and deaths. Statistically, there is data to support this. In high income countries, mental or substance abuse disorders can be attributed to 80% of suicide deaths. In low income countries, the percentage is slightly lower at 70%. Mental illnesses that have been associated with suicide risk include Major depressive disorder (MDD), anxiety disorders, bipolar disorder, dysthymia, and schizophrenia.
Physical Health Conditions
In addition to mental disorders, physical health issues have an impact on suicide risk. After adjusting for age, sex, mental health, and substance use diagnoses, nine conditions have been positively associated with suicide risk. The study claimed this association with the following conditions: back pain, brain injury, cancer, congestive heart failure, COPD, epilepsy, HIV/AIDS, migraine, and sleep disorders. The risk of suicide in people with traumatic brain injuries is almost nine times higher than normal which makes it the highest risk condition. Comorbidity of conditions was also shown to significantly increase the risk of suicide.
Body Mass Index
Risk of suicide may decrease with increased weight and is low in obese persons. The connection is not well understood, but it is hypothesized that elevated body weight results in higher circulating levels of tryptophan, serotonin, and leptin, which in turn reduces impulsivity.
However, other studies indicate that suicide rates increase with extreme obesity, and it is difficult to control for conflating factors such as BMI-related differences in longevity, which have a significant bearing on suicide rates.
Physical Illness and Functional Disability in Older Adults
In adults aged 65 and older, suicidal behavior has been associated with certain functional disabilities and specific conditions. These positively associated conditions and disabilities are the following: malignant diseases, neurological disorders, pain, COPD, liver disease, male genital disorders, and arthritis. Generally speaking, illnesses that threaten the independence of a person, make them doubt their usefulness, value or dignity, or minimize their pleasure with life are more likely to be suicidogenic.
Season
The idea that suicide is more common during the winter holidays (including Christmas in the northern hemisphere) is a myth, generally reinforced by media coverage associating suicide with the holiday season. The National Center for Health Statistics found that suicides drop during the winter months, and peak during spring and early summer. Considering that there is a correlation between the winter season and rates of depression, there are theories that this might be accounted for by capability to die by suicide and relative cheerfulness.
Suicide has also been linked to other seasonal factors.
Seasonal allergies have shown potential impacts on rates of suicide. Based on the reaction that allergens cause, animal models have shown an increase in anxiety-like behavior, reduced social interaction, and aggressive behavior which can be considered endophenotypes for suicidal behavior.
There is significant variation in suicide risk by day of the week, which is greater than any seasonal variation.
Trends
Certain time trends can be related to the type of death. In the United Kingdom for example, the steady decline in suicides between 1960 and 1971 may be due to the near total removal of carbon monoxide from domestic gas supplies. This removal occurred rapidly as society switched primarily from coal gas to natural gas during the 1960s. By 1971, natural gas had taken over 69% of the domestic consumer market.
Methods vary across cultures, and the easy availability of lethal agents and materials plays a role.
Due to social stigma and misclassified cause of death, reported suicide rated are never exact. It is estimated that in the year 2000, global number of suicides were 791,855. As of 2019, there were 703,220 reported instances of suicide. This is a relative difference of 11%. This trend shows a decrease in suicide deaths, however, there is contradicting evidence which shows an overall increase in suicide. This discrepancy requires further research and comparison.
There is the possibility that one individual may have multiple suicide attempts, however, they can only have one suicide. Suicide attempts are up to 20 times more frequent than suicides.
An increase in U.S. baseline temperature due to global warming projects an increase in suicide. With an increase between 1 and 6 degrees Celsius above the baseline, climate change‐attributable suicide in the United States is expected to increase from 283 to 1,660 cases.
Historical data show lower suicide rates during periods of war. However, this has been questioned in more recent studies, which showed a more complex picture than was previously conceived. More research is required to fully understand this complicated relationship.
See also
Copycat suicide
Suicide epidemic
Suicide in the military
References
Suicide
Suicide
Suicide rates
Mental health by country | Epidemiology of suicide | [
"Biology",
"Environmental_science"
] | 3,261 | [
"Behavior",
"Human behavior",
"Epidemiology",
"Environmental social science",
"Suicide"
] |
2,252,898 | https://en.wikipedia.org/wiki/Martinet%20dioxindole%20synthesis | The Martinet dioxindole synthesis was first reported in 1913 by J. Martinet. It is a chemical reaction in which a primary or secondary aniline or substituted aromatic amine is condensed with ethyl or methyl ester of mesoxalic acid to make a dioxindole in the absence of oxygen.
Proposed mechanism
In the first step, the amino group on the aniline (1) attacks the carbonyl of the ethyl oxomalonate (2). A proton from the nitrogen is extracted by the oxygen and an alcohol group forms (3). The carbonyl re-forms to make a keto group and an ethanol molecule leaves (4). Next, a ring closing reaction occurs by the bond from the aromatic benzene ring attacking the partially positive carbonyl to form a five-member ring (5). After a proton transfer (6), an isomerization or a [1,3] hydride shift occurs and aromaticity is restored to the six-membered ring (7). In the presence of base, the ester is hydrolyzed, ethanol is lost (8) and a decarboxylation occurs (9). The resulting product is the desired dioxindole (10).
In the presence of oxygen, dioxindole converts to isatin through oxidation.
Applications
The Martinet dioxindole synthesis is utilized in the preparation of oxindole derivatives. Oxindole derivatives found in natural products are gaining popularity in research because of their structural diversity. 3-substituted-3-hydroxy-2-oxindole is the central structure of a wide variety of biologically important compounds found in natural products. The 3-substituted-3-hydroxy-2-oxindole structure holds anti-oxidant, anti-cancer, anti-HIV, and neuroprotective properties. The utilization of this core structure for drug synthesis and the relevant cellular pathways involved are being extensively studied. The enantio-selective addition of 3-substituted oxindole derivatives to different electrophiles gives access to chiral 3,3-disubstituted oxindole derivatives. The dioxindole is a strong nucleophile for the Michael addition of dioxindoles to nitroalkenes in order to obtain 3,3-disubstituted oxindole derivatives.
Experimental examples
The Martinet dioxindole synthesis proceeds with an alkoxyaniline, 3,4,5-trimethoxyaniline, which reacts with an oxomalonic ester in glacial acetic acid to synthesize 2-carbethoxy-4,5,6-trimethoxyindoxyl, 2-carbethoxy-3,4,5,6-tetramethoxyindole and 4,5,6-trimethoxy-3-hydroxy-3-carbethoxyindole.
Dioxindole
Dioxindole is a non-aromatic heterocyclic organic compound. It has a bicyclic structure consisting of a six-membered aromatic ring fused to a five-membered nitrogen containing ring. It is a hydroxy derivative of oxindole first prepared by reducing isatin with sodium amalgam in an alkaline solution.
See also
Indole
Oxindole
References
Indole forming reactions
Name reactions | Martinet dioxindole synthesis | [
"Chemistry"
] | 702 | [
"Name reactions"
] |
2,253,139 | https://en.wikipedia.org/wiki/Gateaux%20derivative | In mathematics, the Gateaux differential or Gateaux derivative is a generalization of the concept of directional derivative in differential calculus. Named after René Gateaux, it is defined for functions between locally convex topological vector spaces such as Banach spaces. Like the Fréchet derivative on a Banach space, the Gateaux differential is often used to formalize the functional derivative commonly used in the calculus of variations and physics.
Unlike other forms of derivatives, the Gateaux differential of a function may be a nonlinear operator. However, often the definition of the Gateaux differential also requires that it be a continuous linear transformation. Some authors, such as , draw a further distinction between the Gateaux differential (which may be nonlinear) and the Gateaux derivative (which they take to be linear). In most applications, continuous linearity follows from some more primitive condition which is natural to the particular setting, such as imposing complex differentiability in the context of infinite dimensional holomorphy or continuous differentiability in nonlinear analysis.
Definition
Suppose and are locally convex topological vector spaces (for example, Banach spaces), is open, and The Gateaux differential of at in the direction is defined as
If the limit exists for all then one says that is Gateaux differentiable at
The limit appearing in () is taken relative to the topology of If and are real topological vector spaces, then the limit is taken for real On the other hand, if and are complex topological vector spaces, then the limit above is usually taken as in the complex plane as in the definition of complex differentiability. In some cases, a weak limit is taken instead of a strong limit, which leads to the notion of a weak Gateaux derivative.
Linearity and continuity
At each point the Gateaux differential defines a function
This function is homogeneous in the sense that for all scalars
However, this function need not be additive, so that the Gateaux differential may fail to be linear, unlike the Fréchet derivative. Even if linear, it may fail to depend continuously on if and are infinite dimensional (i.e. in the case that is an unbounded linear operator). Furthermore, for Gateaux differentials that linear and continuous in there are several inequivalent ways to formulate their continuous differentiability.
For example, consider the real-valued function of two real variables defined by
This is Gateaux differentiable at with its differential there being
However this is continuous but not linear in the arguments In infinite dimensions, any discontinuous linear functional on is Gateaux differentiable, but its Gateaux differential at is linear but not continuous.
Relation with the Fréchet derivative
If is Fréchet differentiable, then it is also Gateaux differentiable, and its Fréchet and Gateaux derivatives agree. The converse is clearly not true, since the Gateaux derivative may fail to be linear or continuous. In fact, it is even possible for the Gateaux derivative to be linear and continuous but for the Fréchet derivative to fail to exist.
Nevertheless, for functions from a Banach space to another complex Banach space the Gateaux derivative (where the limit is taken over complex tending to zero as in the definition of complex differentiability) is automatically linear, a theorem of . Furthermore, if is (complex) Gateaux differentiable at each with derivative
then is Fréchet differentiable on with Fréchet derivative . This is analogous to the result from basic complex analysis that a function is analytic if it is complex differentiable in an open set, and is a fundamental result in the study of infinite dimensional holomorphy.
Continuous differentiability
Continuous Gateaux differentiability may be defined in two inequivalent ways. Suppose that is Gateaux differentiable at each point of the open set One notion of continuous differentiability in requires that the mapping on the product space
be continuous. Linearity need not be assumed: if and are Fréchet spaces, then is automatically bounded and linear for all .
A stronger notion of continuous differentiability requires that
be a continuous mapping
from to the space of continuous linear functions from to Note that this already presupposes the linearity of
As a matter of technical convenience, this latter notion of continuous differentiability is typical (but not universal) when the spaces and are Banach, since is also Banach and standard results from functional analysis can then be employed. The former is the more common definition in areas of nonlinear analysis where the function spaces involved are not necessarily Banach spaces. For instance, differentiation in Fréchet spaces has applications such as the Nash–Moser inverse function theorem in which the function spaces of interest often consist of smooth functions on a manifold.
Higher derivatives
Whereas higher order Fréchet derivatives are naturally defined as multilinear functions by iteration, using the isomorphisms higher order Gateaux derivative cannot be defined in this way. Instead the th order Gateaux derivative of a function in the direction is defined by
Rather than a multilinear function, this is instead a homogeneous function of degree in
There is another candidate for the definition of the higher order derivative, the function
that arises naturally in the calculus of variations as the second variation of at least in the special case where is scalar-valued. However, this may fail to have any reasonable properties at all, aside from being separately homogeneous in and It is desirable to have sufficient conditions in place to ensure that is a symmetric bilinear function of and and that it agrees with the polarization of
For instance, the following sufficient condition holds . Suppose that is in the sense that the mapping
is continuous in the product topology, and moreover that the second derivative defined by () is also continuous in the sense that
is continuous. Then is bilinear and symmetric in and By virtue of the bilinearity, the polarization identity holds
relating the second order derivative with the differential Similar conclusions hold for higher order derivatives.
Properties
A version of the fundamental theorem of calculus holds for the Gateaux derivative of provided is assumed to be sufficiently continuously differentiable. Specifically:
Suppose that is in the sense that the Gateaux derivative is a continuous function Then for any and where the integral is the Gelfand–Pettis integral (the weak integral) ().
Many of the other familiar properties of the derivative follow from this, such as multilinearity and commutativity of the higher-order derivatives. Further properties, also consequences of the fundamental theorem, include:
(The chain rule) for all and (Importantly, as with simple partial derivatives, the Gateaux derivative does satisfy the chain rule if the derivative is permitted to be discontinuous.)
(Taylor's theorem with remainder)Suppose that the line segment between and lies entirely within If is then where the remainder term is given by
Example
Let be the Hilbert space of square-integrable functions on a Lebesgue measurable set in the Euclidean space The functional
where is a real-valued function of a real variable and is defined on with real values, has Gateaux derivative
Indeed, the above is the limit of
See also
References
.
.
.
.
.
.
Generalizations of the derivative
Topological vector spaces | Gateaux derivative | [
"Mathematics"
] | 1,451 | [
"Topological vector spaces",
"Vector spaces",
"Space (mathematics)"
] |
2,253,446 | https://en.wikipedia.org/wiki/Coking | Coking is the process of heating coal in the absence of oxygen to a temperature above to drive off the volatile components of the raw coal, leaving behind a hard, strong, porous material with a high carbon content called coke. Coke is predominantly carbon. Its porous structure provides a high surface area, allowing it to burn more rapidly, much like how a bundle of tinder burns faster than a solid wooden log. As such, when a kilogram of coke is burned, it releases more heat than a kilogram of the original coal.
Application to smelting iron
Coke is used as fuel in a blast furnace. In a continuous process, coke, iron ore, and limestone are mixed together and placed in the top of the blast furnace, and at the bottom liquid iron and waste slag are removed. The raw materials continuously move down the blast furnace. During this continuous process more raw materials are placed at the top, and as the coke moves down, it must withstand the ever-increasing weight of the materials above it. It is the ability to withstand this crushing force, in addition to its high energy content and rapid combustion, that makes coke ideal for use in blast furnaces.
Petroleum coking
"Coking is a refinery unit operation that upgrades material called bottoms from the atmospheric or vacuum distillation column into higher-value products and produces petroleum coke—a coal-like material". In heterogeneous catalysis, the process is undesirable because the clinker blocks the catalytic sites. Coking is characteristic of high temperature reactions involving hydrocarbon feedstocks. Typically coking is reversed by combustion, provided that the catalyst will tolerate such.
A simplified equation for coking is shown in the case of ethylene:
3 C2H4 → 2 C ("coke") + 2 C2H6
A more realistic but complex view involves the alkylation of an aromatic ring of a coke nucleus. Acidic catalysts are thus especially prone to coking because they are effective at generating carbocations (i.e., alkylating agents).
Coking is one of several mechanisms for the deactivation of a heterogeneous catalyst. Other mechanisms include sintering, poisoning, and solid-state transformation of the catalyst.
See also
Coking factory
Gas to liquids
References
Coking works
Catalysis | Coking | [
"Chemistry"
] | 477 | [
"Catalysis",
"Chemical kinetics"
] |
12,008,212 | https://en.wikipedia.org/wiki/Linear%20park | A linear park is a type of park that is significantly longer than it is wide. These linear parks are strips of public land running along canals, rivers, streams, defensive walls, electrical lines, or highways and shorelines. Examples of linear parks include everything from wildlife corridors to riverways to trails, capturing the broadest sense of the word. Other examples include rail trails ("rails to trails"), which are disused railroad beds converted for recreational use by removing existing structures. Commonly, these linear parks result from the public and private sectors acting on the dense urban need for open green space. Linear parks stretch through urban areas, coming through as a solution for the lack of space and need for urban greenery. They also effectively connect different neighborhoods in dense urban areas as a result, and create places that are ideal for activities such as jogging or walking. Linear parks may also be categorized as greenways. In Australia, a linear park along the coast is known as a foreshoreway. When being designed, linear parks appear unique as they are planned around the public's opinion of how the space will affect them.
North America
Possibly the earliest example is the Emerald Necklace, which consists of a , or 445 hectare chain of parks linked by parkways (a broad, landscaped highway) and waterways in Boston and Brookline, Massachusetts, U.S. The name comes from the way the planned chain appears to hang from the "neck" of the Boston peninsula. This system of linear parks was designed by Frederick Law Olmsted to connect the Boston Common and Public Garden (1837) to Franklin Park (Boston), also known as the "crown jewel" of Olmstead's work in Boston. The project began around 1878 with efforts to clean up and control the marshy area which later became the Back Bay and the Fens. In 1880, Olmsted proposed that the Muddy River be included in the park plan as the current dredged into a winding stream and was directed into the Charles River. Olmsted's vision of a linear park of walking paths along a gentle stream connecting numerous small ponds was complete by the turn of the century, but never completed the section to Boston Harbor. The subsequent development of the automobile industry and roads severely disrupted the original concept.
In recent years, prevalent examples of linear parks that have seen high levels of visitors are the High Line in New York City and the Bloomingdale Trail in Chicago. The High Line in New York City is a 1.4 mile (2.2 km) long rail trail and greenway, having been built on a portion of a defunct rail line as well as constructed to have greenery all throughout. Like its Paris counterpart Promenade Plantee, the High Line has been transformed into a linear park that allows for activities such as sight-seeing and exercise, while being elevated. The High Line's annual budget is funded almost entirely by park visitors, though it is operated by the New York City Department of Parks and Recreation license agreement. Bloomingdale Trail in Chicago is the longest linear park in the Western Hemisphere, and the second-longest linear park in the world, with a length of 2.7 miles (4.3 km), just under Paris' Promenade Plantee at 2.9 miles (4.6 km). Bloomingdale Trial was created by converting an elevated portion of the former Bloomingdale railway to this linear park, which features trees, flowers, plants, shrubbery, grass, light posts, and benches throughout. The greenway transverses through the neighborhoods of Logan Square, Humboldt Park, and West Town.
In some cities, many linear parks run through residential areas. In this case, the front of the house will face the streets, while the back faces a small linear park containing a pathway, trees and grass connecting different areas together. There are examples of this in some US cities and some Canadian cities, such as Saskatoon, Canada. Houses connected with linear parks are more common in suburban and rural areas where space is much less in-demand.
Atlanta BeltLine
A linear park system under development in Atlanta, Georgia is the BeltLine. Part of the foundation for this project consisted of reclaiming of unused rail trails. Totaling approximately , the BeltLine will include a trail and light rail line on the existing tracks instead of a road. The vision of the BeltLine is to attempt to balance out resident demographics within the city, allowing for all associated to the BeltLine to benefit.
Europe
In England, linear parks have also been created around waterways, especially in cities where the terrain is such that rivers and brooks have significant flood plains. Such land cannot sensibly be used for urban development and so it is set aside as a civic amenity. The settlement Milton Keynes makes extensive use of linear parks, with nine different examples that include the flood plains of the Great Ouse and of its tributaries (the Ouzel and some brooks). In the UK, Milton Keynes ranked highest in a national comparison of open urban areas available to residents.
In Greater London, Essex and Hertfordshire, the Lee Valley Park is a linear park, stretching for long, much of it green spaces running along the flood plains of the River Lea from the River Thames to Ware, through areas such as Stratford, Clapton, Tottenham, Enfield, Walthamstow, Cheshunt, Broxbourne and Hoddesdon in an area renowned as the Lea Valley. Greater London's largest park, Lee Valley Park is more than four times the size of Richmond Park, extending beyond Greater London's borders into the neighboring counties of Hertfordshire and Essex.
A more recent example of a linear park is the Berlin Mauerpark, which was built on a part of the former Berlin Wall area and its adjacent former death strip.
Planty Park, Kraków, Poland). It encircles the Stare Miasto (Old Town), where the Medieval city walls used to stand until the early 19th century. The park has an area of and a length of . It consists of a chain of thirty smaller gardens designed in varied styles and adorned with numerous monuments and fountains. The park forms a scenic walkway popular with Cracovians. In summer, sprinkled with ponds and refreshment stalls, it is a cool and shady retreat from the nearby bustling streets.
Asia
In Hong Kong, a prominent example of a linear park is the Avenue of Stars. Located at the waterfront surrounding East Tsim Sha Tsui, the Avenue of Stars is a 440-meter(0.27 mi.) promenade offering scenic views to the public. As a public amenity, the park provides much needed urban space to the dense city of Hong Kong. The walking road itself is dedicated to famous Hong Kong celebrities, and as such is an attractive tourist area lined with souvenir stalls at some sections.
In addition to the dynamic waterfront location, the Avenue of Stars provides visitors a "front-row seat"(stand) to the Symphony of Lights, the world's largest light and sound show. It is also around this area that the famed Star Ferry can be observed and even ridden.
In Singapore, wild growth and shrubbery that's taken over a former KTM rail line has been encouraged and maintained through public opinion. Convincing the Singaporean government of the land's value, the citizens of Singapore were able to turn a neglected KTM railway in to a linear park that now runs 10 km(6.21 mi) long and offers unique perspectives into Singaporean wildlife. Rail Corridor differs from the typical linear park in a way that promotes and integrates the biodiversity and ecosystem throughout—covering 93 different species—while serving as an excellent outdoor trail to get active in.
List of linear parks
Europe
Belgium
Parc de la Senne - Zennepark, Brussels
France
Promenade plantée, Paris
Germany
Mauerpark in Berlin
Mittellandkanal, Hannover
Kattenbrook-Park, Hannover
Ireland
Dodder Park, Dublin
Lansdowne Valley Park, Dublin
Portugal
Tagus Linear Park, Póvoa de Santa Iria (River Tagus)
Romania
Liniei Park, Bucharest
Spain
Sagera Linear Park, Barcelona
Parc de la Rambla de Sants, Barcelona
Turia Gardens (Jardín del Turia), Valencia
United Kingdom
Brampton Valley Way in Northamptonshire and Leicestershire, England
Eastside City Park, Birmingham, England
Hogsmill River Park, London, England
Mile End Park, East London, England
North America
Canada
Beltline Linear Park and West Toronto Railpath, Toronto, Ontario
Grand Concourse (St. John's), Newfoundland: a walkway system with linear parks
Meewasin Trail, Saskatoon, Saskatchewan
Parc linéaire de la rivière Saint-Charles, Québec City, Québec
Parc Linéaire Le P'tit Train du Nord, Saint-Jérôme - Mont-Laurier, Quebec.
Strathcona Linear Park, Vancouver, British Columbia
United States
Alewife Linear Park, Massachusetts
Atlanta BeltLine, Atlanta, Georgia
Bloomingdale Trail (The 606), Chicago, Illinois
Blue Ridge Parkway, North Carolina and Virginia
Brickell Key Baywalk, Miami, Florida
Buffalo Bayou Park, Houston, Texas
Burnham Greenway, Chicago, Illinois
Charles River Esplanade, Boston, Massachusetts
Chesapeake and Ohio Canal National Historical Park, Washington, D.C., West Virginia, and Maryland
Delaware and Raritan Canal State Park, Central New Jersey
Dequindre Cut, Detroit, Michigan
East Boston Greenway, Boston, Massachusetts
Eastern Parkway, New York City
Elizabeth River Parkway, Union County, New Jersey
Embarcadero, San Francisco, California
Freeway Park, Seattle, Washington
George Redman, East Providence-Providence, Rhode Island
Grand Park, Los Angeles, California
Great Highway, San Francisco, California
High Line, New York, New York
Hollywood Central Park, Los Angeles, California
Hoover-Mason Trestle, Bethlehem, Pennsylvania
Hudson River Park, New York, New York
Illinois Prairie Path, Dupage County, Illinois
Indianapolis Cultural Trail, Indianapolis, Indiana
James River Park System, Richmond, Virginia
Little Sugar Creek Greenway, Charlotte, North Carolina
Miami Riverwalk, Miami Baywalk, and future Miami River Greenway
Midtown Greenway and trails network of Minneapolis, Minnesota
Mosholu Parkway, The Bronx, New York City
Ocean Parkway, New York City
Passaic River Parkway, Union County, New Jersey
Pastor Willie James Ford, Sr. Linear Park, Deerfield Beach, Florida
Pelham Parkway, The Bronx, New York City
Rahway River Parkway, Union County, New Jersey
Rose Kennedy Greenway, Boston, Massachusetts
Riverfront Park (Arkansas River Trail), Little Rock, Arkansas
Rotary Trail, Birmingham, Alabama
Salesforce Park, San Francisco
San Antonio River Walk, San Antonio, Texas
Stowe Recreation Path, Stowe, Vermont
The Loop, Tucson, Arizona
The Underline, Miami-Dade County, Florida
Vanderbilt Motor Parkway, Queens, New York City
Walkway over the Hudson State Historic Park, Poughkeepsie and Highland, New York
Washington & Old Dominion Railroad Regional Park, Northern Virginia
Mexico
Línea Verde, Aguascalientes
Parque Lineal (Puerto Vallarta)
South America
Brazil
Parque Linear Tiquatira, São Paulo
Asia
Hong Kong
Avenue of Stars, Hong Kong
Singapore
Rail Corridor, Singapore
Iran
Seyyed morteza linear park, kashmar
Israel
Yarkon Park, Tel Aviv
Japan
Odori Park, Sapporo
Philippines
Plaza Moriones, Manila
Camaligan River Park, Camaligan, Camarines Sur
Iloilo River Esplanade, Iloilo City
Taiwan
Calligraphy Greenway, Taichung
South Korea
Seoullo 7017, Seoul
United Arab Emirates
Al zorah linear park, Ajman
Australia
Stirling Linear Park, near Adelaide
Sturt River Linear Park, near Adelaide
The Goods Line, Sydney
Torrens Linear Park, Adelaide
See also
Boardwalk
Footpath
Foreshoreway
Greenway (landscape)
Promenade
Trail
Urban park
Wildlife corridor
Notes
References
Parks
Greenways
Footpaths
Urban public parks
Landscape architecture
Land management
Urban studies and planning terminology
Sustainable urban planning
Types of thoroughfares | Linear park | [
"Engineering"
] | 2,439 | [
"Landscape architecture",
"Architecture"
] |
12,008,347 | https://en.wikipedia.org/wiki/Bioelectromagnetics%20%28journal%29 | Bioelectromagnetics is a peer-reviewed scientific journal published by Wiley-Liss that specializes in articles about the biological effects from and applications of electromagnetic fields in biology and medicine. It is the official journal of the Bioelectromagnetics Society, the European Bioelectromagnetics Association, and the Society for Physical Regulation in Biology and Medicine.
Abstracting and indexing
The journal is abstracted and indexed in Medline, searchable via PubMed and indexed in Index medicus. According to the Journal Citation Reports, the journal has a 2020 impact factor of 2.010.
See also
Bioelectrochemistry (journal)
References
External links
Biophysics journals
Biotechnology journals
Academic journals established in 1980
Wiley (publisher) academic journals
Bioelectromagnetics
Electromagnetism journals | Bioelectromagnetics (journal) | [
"Biology"
] | 165 | [
"Biotechnology literature",
"Biotechnology journals"
] |
12,008,564 | https://en.wikipedia.org/wiki/Tre%20recombinase | Tre recombinase is an experimental enzyme that in lab tests has removed DNA inserted by HIV from infected cells. Through selective mutation, Cre recombinase which recognizes loxP sites are modified to identify HIV long terminal repeats (loxLTR) instead. As a result, instead of performing Cre-Lox recombination, the new enzyme performs recombination at HIV provirus sites.
The structure of Tre in complex with loxLTR has been resolved (), allowing for analyzing the roles of individual mutations.
References
External links
Genetics
Molecular biology | Tre recombinase | [
"Chemistry",
"Biology"
] | 120 | [
"Biochemistry",
"Genetics",
"Molecular biology"
] |
12,008,648 | https://en.wikipedia.org/wiki/Phreatic%20zone | The phreatic zone, saturated zone, or zone of saturation, is the part of an aquifer, below the water table, in which relatively all pores and fractures are saturated with water. The part above the water table is the vadose zone (also called unsaturated zone).
The phreatic zone size, color, and depth may fluctuate with changes of season, and during wet and dry periods.<ref
></ref
><ref
></ref
> Depending on the characteristics of soil particles, their packing and porosity, the boundary of a saturated zone can be stable or instable, exhibiting fingering patterns known as Saffman–Taylor instability. Predicting the onset of stable vs. unstable drainage fronts is of some importance in modelling phreatic zone boundaries.<ref
> Dynamics of Drainage and Viscous Fingering
in Transport in Porous Media
Note that zones "behind" the drainage front are areas on the 'dry' (low-viscosity) (typically above / beyond the 'wet' zone).
</ref
>
See also
Index: Aquifer articles
References
Aquifers
Cave geology
Hydrogeology
Soil physics | Phreatic zone | [
"Physics",
"Environmental_science"
] | 244 | [
"Hydrology",
"Applied and interdisciplinary physics",
"Soil physics",
"Hydrology stubs",
"Aquifers",
"Hydrogeology"
] |
12,008,694 | https://en.wikipedia.org/wiki/Junction%20temperature | Junction temperature, short for transistor junction temperature, is the highest operating temperature of the actual semiconductor in an electronic device. In operation, it is higher than case temperature and the temperature of the part's exterior. The difference is equal to the amount of heat transferred from the junction to case multiplied by the junction-to-case thermal resistance.
Microscopic effects
Various physical properties of semiconductor materials are temperature dependent. These include the diffusion rate of dopant elements, carrier mobilities and the thermal production of charge carriers. At the low end, sensor diode noise can be reduced by cryogenic cooling. On the high end, the resulting increase in local power dissipation can lead to thermal runaway that may cause transient or permanent device failure.
Maximum junction temperature calculation
Maximum junction temperature (sometimes abbreviated TJMax) is specified in a part's datasheet and is used when calculating the necessary case-to-ambient thermal resistance for a given power dissipation. This in turn is used to select an appropriate heat sink if applicable. Other cooling methods include thermoelectric cooling and coolants.
In modern processors from manufacturer such as Intel, AMD, Qualcomm, the core temperature is measured by a network of sensors. Every time the temperature sensing network determines that a rise above the specified junction temperature (), is imminent, measures such as clock gating, clock stretching, clock speed reduction and others (commonly referred to as thermal throttling) are applied to prevent the temperature to raise further. If the applied mechanisms are not compensating enough for the processor to stay below the junction temperature, the device may shut down to prevent permanent damage.
An estimation of the chip-junction temperature can be obtained from the following equation:
where:
= ambient temperature for the package [°C]
= junction to ambient thermal resistance [°C / W]
= power dissipation in package [W]
Measuring junction temperature (TJ)
Many semiconductors and their surrounding optics are small, making it difficult to measure junction temperature with direct methods such as thermocouples and infrared cameras.
Junction temperature may be measured indirectly using the device's inherent voltage/temperature dependency characteristic. Combined with a Joint Electron Device Engineering Council (JEDEC) technique such as JESD 51-1 and JESD 51-51, this method will produce accurate measurements. However, this measurement technique is difficult to implement in multi-LED series circuits due to high common mode voltages and the need for fast, high duty cycle current pulses. This difficulty can be overcome by combining high-speed sampling digital multimeters and fast high-compliance pulsed current sources.
Once junction temperature is known, another important parameter, thermal resistance (Rθ), may be calculated using the following equation:
Junction temperature of LEDs and laser diodes
An LED or laser diode’s junction temperature (Tj) is a primary determinate for long-term reliability; it also is a key factor for photometry. For example, a typical white LED output declines 20% for a 50 °C rise in junction temperature. Because of this temperature sensitivity, LED measurement standards, like IESNA’s LM-85 , require that the junction temperature is determined when making photometric measurements.
Junction heating can be minimized in these devices by using the Continuous Pulse Test Method specified in LM-85. An L-I sweep conducted with an Osram Yellow LED shows that Single Pulse Test Method measurements yield a 25% drop in luminous flux output and DC Test Method measurements yield a 70% drop.
See also
Safe operating area
P-N Junction
Metal Semiconductor Junction
References
Semiconductors | Junction temperature | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 740 | [
"Electrical resistance and conductance",
"Physical quantities",
"Semiconductors",
"Materials",
"Electronic engineering",
"Condensed matter physics",
"Solid state engineering",
"Matter"
] |
12,008,922 | https://en.wikipedia.org/wiki/HD%2093205 | HD 93205, or V560 Carinae, is a binary stellar system, in the Carina Nebula (NGC 3372) in the constellation Carina. It consists of two massive O-stars that revolve around each other in 6 days.
The more massive member of the pair is an O3.5 main sequence star. The spectrum shows some ionised nitrogen and helium emission lines, indicating some mixing of fusion products to the surface and a strong stellar wind. The mass calculated from apsidal motion of the orbits is . This is somewhat lower than expected from evolutionary modelling of a star with its observed parameters.
The less massive member is an O8 main sequence star of approximately . It moves in its orbit at a speed of over 300 km/s and is considered to be a relativistic binary, which causes the apses of the orbit to change in a predictable way.
In 1985, Arnout van Genderen et al. reported that the star appeared to be "variable in brightness". Eleonora A. Antokhina et al. confirmed the star's variability in the year 2000, and presented an extensive analysis of the light curve. The star was given its variable star designation, V560 Carinae, in 2001. The closeness of the two stars causes them to become deformed, and this means that the observed brightness of the system varies slightly every six days during its orbit. The total amplitude of the variation is only 0.02 magnitudes.
It is generally considered as a member of the open cluster Trumpler 16. Among its neighbors are some of the most massive and luminous stars in the galaxy, like Eta Carinae, HD 93250 and the binary WR 25. It lies five arc-minutes from Eta Carinae.
References
Carina Nebula
O-type main-sequence stars
Spectroscopic binaries
Carinae, V560
Durchmusterung objects
093205
Carina (constellation)
Emission-line stars
Rotating ellipsoidal variables | HD 93205 | [
"Astronomy"
] | 411 | [
"Carina (constellation)",
"Constellations"
] |
12,009,197 | https://en.wikipedia.org/wiki/Ethylenediamine%20pyrocatechol | Ethylenediamine pyrocatechol (EDP), also known as ethylenediamine-pyrocatechol-water (EPW), is an anisotropic etchant solution for silicon. A typical formulation consists of ethylenediamine, pyrocatechol, pyrazine and water. It is carcinogenic and very corrosive. It is mainly used in research labs, and is not used in mainstream semiconductor fabrication processes.
References
Polyamines
Catechols | Ethylenediamine pyrocatechol | [
"Chemistry"
] | 110 | [
"Organic chemistry stubs"
] |
12,009,244 | https://en.wikipedia.org/wiki/Buffered%20oxide%20etch | Buffered oxide etch (BOE), also known as buffered HF or BHF, is a wet etchant used in microfabrication. It is a mixture of a buffering agent, such as ammonium fluoride , and hydrofluoric acid (HF). Its primary use is in etching thin films of silicon nitride (Si3N4) or silicon dioxide (SiO2), by the reaction:
Concentrated HF (typically 49% HF in water) etches silicon dioxide too quickly for good process control and also peels photoresist used in photolithographic patterning. Buffered oxide etch is commonly used for more controllable etching. Buffering HF with results in a solution with a more stable pH; thus, more stable concentrations of HF and , and a more stable etch rate.
Some oxides produce insoluble products in HF solutions. Thus, HCl may be added to BHF solutions in order to dissolve these insoluble products and produce a higher quality etch.
Production
Buffered oxide etch can be produced in laboratory quantities by dissolving NH4F powder into water, and adding a solution of HF.
Uses
A buffered oxide etch solution of 6:1 volume ratio of 40% NH4F to 49% HF will etch thermally grown oxide at approximately 2 nanometres per second at 25 degrees Celsius. Temperature can be increased to raise the etching rate. Continuous stirring of the solution during the etching process helps to have a more homogeneous solution, which may etch more uniformly by removing etched material from the surface.
Buffered oxide etch can be used in the metallographic etching of titanium alloys. Newer Ti-alloys (such as Ti-Cu and Ti-Mo) are not etched as reliably by typical Ti-etching reagents, but can be etched by BOE and ammonium bifluoride.
HF solution buffered with can be used to provide better etching of zeolite for the creation of larger pores, to improve the characteristically poor rate of diffusion in these microporous structures. Simple HF solutions (and other acidic methods of etching) show high selectivity in removing aluminum from zeolites, reducing the number of potential Brønsted acid sites, and subsequently reducing certain catalytic performance. However, the addition of a buffer results in a solution with more HF and present, which removes Al and Si in more equal proportion.
References
Etching (microfabrication) | Buffered oxide etch | [
"Materials_science"
] | 540 | [
"Microtechnology",
"Etching (microfabrication)"
] |
12,009,271 | https://en.wikipedia.org/wiki/Turrid | Turrid, plural turrids, is a common name for a very large group of predatory sea snails, marine gastropod mollusks which until recently were all classified in the family Turridae. However, recently the family was discovered to be polyphyletic and therefore was split into a number of families.
The original family Turridae used to contain more than 4,000 species. the Turridae (sensu Powell 1966) It was the largest mollusk family and the largest group of marine caenogastropods. There were approximately 27,000 described scientific names (accepted names plus synonyms) within the family Turridae. Turrids constituted more than half of the predatory species of gastropods in some parts of the world (Taylor et al. 1980). However, this very large family was shown to be polyphyletic, and in 2011 it was divided into 13 separate families by Bouchet, Kantor, Sysoev and Puilandre.
The single most complete collection of turrids in museums worldwide is in the Academy of Natural Sciences of Philadelphia malacology collection; this is because of specialized collecting by the American malacologist Virginia Orr Maes (1920-1986).
Distribution
Turrids are found worldwide in every sea and ocean from both poles to the tropics. They occur from the low-intertidal zone to depths of more than eight thousand metres (e.g., Xanthodaphne levis Sysoev, 1988, collected between 7974–8006 m, in the Bougainville Trench). However, most species of turrids are found in the neritic zone.
Shell description
Most turrids are rather small, with a height under 2 cm, but the adult shells of different species are between 0.3 and 11.4 cm in height.
The shape of the shells is more or less fusiform, varying from very high-spired to broadly ovate. The whorls are elongate to broadly conical.
The sculpture is very variable in form, but most have axial sculpture or spiral sculpture (or a combination of both). Others may be reticulate, beaded, nodulose, or striate.
The aperture of the shell very often has a V-shaped sinus or notch, an indentation on the upper end of the outer lip. This accommodates the anal siphonal notch, commonly known as the "turrid notch". The siphonal canal is usually open, varying from short and stocky to long and slender. The position of the turrid notch of the shell and the form and sculpture of the whorls have traditionally been the primary methods of classifying the turrids.
The columella is usually smooth and only seldom shows labial plicae. The operculum is horny, but is not always present.
Turrids are carnivorous, predatory gastropods. Most species have a poison gland used with the toxoglossan radula, used to prey on vertebrates and invertebrate animals (mostly polychaete worms) or in self-defense. Some turrids have lost the radula and the poison gland. The radula, when present, has two or three teeth in a row. It lacks lateral teeth and the marginal teeth are of the wishbone or duplex type. The teeth with a duplex form are not shaped from two distinct elements but grow from a flat plate, by thickening at the edges of the teeth and elevation of the rear edge from the membrane.
Female turrids lay their eggs in lens-shaped capsules.
History of the taxonomy
The turrids were perceived as one of the most difficult groups to study because of a large number of supra-specific described taxa, which are complicated by their species diversity. Although some species of turrids are relatively common, many are rare, some being known only from single specimens; this is another factor that makes studying the group difficult.
2011 taxonomy
The previous (2005) classification system for the group was thoroughly changed by the publication in 2011 of the article Bouchet P., Kantor Yu.I., Sysoev A. & Puillandre N. (2011) A new operational classification of the Conoidea. Journal of Molluscan Studies 77: 273-308. The authors presented a new classification of the Conoidea on the genus level, based on anatomical characters but also on the molecular phylogeny as presented by Puillandre N., et al., 2008. The polyphyletic family Turridae was resolved into 13 monophyletic families (containing 358 currently recognized genera and subgenera) :
Conorbidae
Borsoniidae
Clathurellidae
Mitromorphidae
Mangeliidae
Raphitomidae
Cochlespiridae
Drilliidae
Pseudomelatomidae (= Crassispiridae)
Clavatulidae
Horaiclavidae
Turridae s.s.
Strictispiridae
2005 taxonomy
According to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005, which attempted to set out a stable taxonomy, this group consisted of the following five subfamilies:
Turrinae H. Adams & A. Adams, 1853 (1838) - synonyms: Pleurotominae Gray, 1838; Lophiotominae Morrison, 1965 (n.a.)
Cochlespirinae Powell, 1942
Crassispirinae McLean, 1971 - synonym: Belinae A. Bellardi, 1875
Zemaciinae Sysoev, 2003
Zonulispirinae McLean, 1971
Genera
Genera in the family Turridae used to include:
Abyssocomitas Sysoev & Kantor, 1986
Acamptogenotia Rovereto, 1899
Aforia Dall, 1889
Anacithara Hedley, 1922
Ancistrosyrinx Dall, 1881
Anticomitas Powell, 1942
Antiguraleus Powell, 1942
Antimelatoma Powell, 1942
Antiplanes Dall, 1902
Aoteadrillia Powell, 1942
Apiotoma Cossmann, 1889
Asperdaphne Hedley, 1922
Austrodrillia Hedley, 1918
Bathybela Kobelt, 1905
Belalora Powell, 1951
Benthoclionella Kilburn, 1974
Buchema Corea, 1934
Burchia Bartsch, 1944
Calcatodrillia Kilburn, 1988
Carinapex Dall, 1924
Carinodrillia Dall, 1919
Carinoturris Bartsch, 1944
Ceritoturris Dall, 1924
Cheungbeia Taylor & Wells, 1994
Clavatula Lamarck, 1801
Clavosurcula Schepman, 1913
Clavus Montfort, 1810
Clionella Gray, 1847
Cochlespira Conrad, 1865
Compsodrillia Woodring, 1928
Conorbela Powell, 1951
Conticosta Laseron, 1954
Crassiclava McLean, 1971
Crassispira Swainson, 1840
Cretaspira Kuroda & Oyama, 1971
Cryptogemma Dall, 1918
Cymakra Gardner, 1937
Danilacarina Bozzetti, 1997
Daphnella Hinds, 1844
Darrylia Garcia, 2008
Decollidrillia Habe & Ito, 1965
Doxospira McLean, 1971
Eosurcula
Epideira Hedley, 1918
Epidirona Iredale, 1931
Fenimorea Bartsch, 1934
Fusiturricula Woodring, 1928
Fusiturris Thiele, 1929
Gemmula Weinkauff, 1875
Graciliclava Shuto, 1983
Haedropleura Monterosato in Bucquoy, Dautzenberg & Dollfus, 1883
Hauturua Powell, 1942
Hemilienardia Boettger, 1895
Heterocithara Hedley, 1922
Hindsiclava Hertlein and Strong, 1955
Horaiclavus Oyama, 1954
Inodrillia Bartsch, 1943
Inquisitor Hedley, 1918
Iotyrris Medinskaya & Sysoev, 2001
Iredalea Oliver, 1915
Irenosyrinx Dall, 1908
Iwaoa Kuroda, 1953
Knefastia Dall, 1919
Kurilohadalia Sysoev & Kantor, 1986
Kurodadrillia Azuma, 1975
Kuroshioturris Shuto, 1961
Leucosyrinx Dall, 1889 :p
Lienardia Jousseaume 1884
Lioglyphostoma Woodring, 1928
Lophiotoma Casey, 1904
Lophioturris Powell, 1964
Liracraea Odhner, 1924
Lora Gistl, 1848
Lucerapex Iredale, 1936
Lusitanops F. Nordsieck, 1968
Maesiella McLean, 1971
Makiyamaia Kuroda, 1961
Marshallena Finlay, 1926
Mauidrillia Powell, 1942
Megasurcula Casey, 1904
Microdrillia Casey, 1903
Micropleurotoma Thiele, 1929
Miraclathurella Woodring, 1928
Monilispira Bartsch & Rehder, 1939
Naskia Sysoev & Ivanov, 1985
Neodrillia Bartsch, 1943
Neoguraleus Powell, 1939
Neopleurotomoides Shuto, 1925
Nihonia McNeil, 1961
Nodotoma Bartsch, 1941
Nquma Kilburn, 1988
Oenopota Moerch, 1852
Paradrillia Makiyama, 1940
Perrona Schumacher, 1817
Philbertia Monterosato, 1884
Phymorhynchus Dall, 1908
Pilsbryspira Bartsch, 1950
Pinguigemmula McNeil, 1961
Plicisyrinx Sysoev & Kantor, 1986
Polystira Woodring, 1928
Pseudexomilus Powell, 1944
Pseudotaranis McLean, 1995
Psittacodrillia Kilburn, 1988
Ptychobela Thiele, 1925
Ptychosyrinx Thiele, 1925
Pusionella Gray, 1847
Pyrgospira McLean, 1971
Rectiplanes Bartsch, 1944
Rhodopetoma Bartsch, 1944
Riuguhdrillia Oyama, 1951
Scaevatula Gofas, 1990
Shutonia van der Bijl, 1993
Sinistrella Meyer, 1887
Spirotropis Sars, 1878
Splendrillia Dell, 1956
Steiraxis Dall, 1896
Stenodrillia Korobkov, 1955
Striatoguraleus Kilburn, 1994
Surcula H. Adams & A. Adams, 1853
Teretia Norman, 1888
Tomella Swainson, 1840
Toxiclionella Powell, 1966
Turricula Schumacher, 1817
Turridrupa Hedley, 1922
Turris Röding, 1798 - type genus
Unedogemmula MacNeil, 1961
Veprecula Melvill, 1917
Vexitomina Powell, 1942
Viridoturris Powell, 1964
Viridrillia Bartsch, 1943
Vitricythara Fargo, 1953
Zemacies Finlay, 1926
Zonulispira Bartsch, 1950
References
Further reading
Kilburn R. N. (1983). "Turridae (Mollusca: Gastropoda) of southern Africa and Mozambique. Part 1. Subfamily Turrinae." Ann. Natal. Mus. 25: 549–585.
McLean J. (1971). "A revised classification of the family Turridae, with the proposal of new subfamilies, genera, and subgenera from the Eastern Pacific". Veliger 14: 114–130.
Powell A. W. B. (1964). "The family Turridae in the Indo-Pacific. Part 1, The subfamily Turrinae". Indo-Pacific Mollusca 1: 227–345.
Tucker J. K. (2004). "Catalog of Recent and fossil turrids (Mollusca: Gastropoda)". Zootaxa 682: 1–1295. preview
External links
(older) Turrid Classification
Mollusc common names
Polyphyletic groups | Turrid | [
"Biology"
] | 2,509 | [
"Phylogenetics",
"Polyphyletic groups"
] |
12,009,413 | https://en.wikipedia.org/wiki/Ames%20process | The Ames process is a process by which pure uranium metal is obtained. It can be achieved by mixing any of the uranium halides (commonly uranium tetrafluoride) with magnesium metal powder or aluminium metal powder.
History
The Ames process was used on August 3, 1942, by a group of chemists led by Frank Spedding and Harley Wilhelm at the Ames Laboratory as part of the Manhattan Project. It is a type of thermite-based purification, which was patented in 1895 by German chemist Hans Goldschmidt. Development of the Ames process came at a time of increased research into mass uranium-metal production. The desire for increased production was motivated by a fear of Nazi Germany's developing nuclear weapons before the Allies. The process originally involved mixing powdered uranium tetrafluoride and powdered magnesium together. This mixture was placed inside an iron pipe that was welded shut on one side and capped shut on another side. This container, called a "bomb" by Spedding, was placed into a furnace. When heated to a temperature of , the contents of the container reacted violently, leaving a 35-gram ingot of pure uranium metal. The process was quickly scaled up; by October 1942 the "Ames Project" was producing metal at a rate of per week. The uranium tetrafluoride and magnesium were sealed in a refractory-lined reactor vessel, still referred to as a "bomb". The thermite reaction was initiated by furnace heating the assembly to ; the large difference in density between slag and metal allowed complete separation in the liquid state, yielding slag-free metal. By July 1943, the production rate exceeded of uranium metal per month. Approximately 1000 tons of uranium ingots were produced at Ames before the process was transferred to industry.
The Ames project received the Army-Navy "E" Award for Excellence in Production on October 12, 1945, signifying 2.5 years of excellence in industrial production of metallic uranium as a vital war material. Iowa State University is unique among educational institutions to have received this award for outstanding service, an honor normally given to industry.
Ames process for rare-earth metals
The metallothermic reduction of anhydrous rare-earth fluorides to rare-earth metals is also referred to as the Ames process.
The study of rare earths was also advanced during World War II: synthetic plutonium was believed to be rare-earth-like, and it was assumed that knowledge of rare earths would assist in planning for and the study of transuranic elements; ion-exchange methods developed for actinide processing were forerunners to processing methods for rare-earth oxides; methods used for uranium were modified for plutonium, which were subsequently the basis for rare-earth metal preparation.
References
Notes
External links
Uranium
Chemical processes
Metallurgical processes
Manhattan Project
Iowa State University | Ames process | [
"Chemistry",
"Materials_science"
] | 580 | [
"Metallurgical processes",
"Metallurgy",
"Chemical processes",
"nan",
"Chemical process engineering"
] |
12,009,633 | https://en.wikipedia.org/wiki/Sociophysiology | Sociophysiology is the "interplay between society and physical functioning" (Freund 1988: 856) involving "collaboration of two neighboring sciences: physiology and sociology" (Mauss 1936: 373). In other words, sociophysiology is physiological sociology, a special science that studies the physiological side of human (and other animals') interrelations (Zeliony 1912: 405–406).
Interdisciplinary field of research
In addition to having been termed an "interdisciplinary area for research, an area which demonstrates the concomitant relationship between physiology and social behavior" (Di Mascio et al. 1955: 4), sociophysiology may also be described as "social ethology" and "social energetics" (Waxweiler 1906: 62). That is, the "physiology of reactive phenomena caused by the mutual excitations of individuals of the same species" (Waxweiler 1906: 62).
The interdisciplinary nature of sociophysiology largely entails a "synthesis of psychophysiology and social interaction" (Adler 2002: 884) such that a "socio-psycho-biological study" (Mauss 1936: 386) of "biologico-sociological phenomena" (Mauss 1936: 385) may ensue. Such "socio-psycho-biological study" has uncovered a "sharing of physiology between people involved in a meaningful interaction" (Adler 2002: 884), as well as "mutually responsive physiologic engagement having normative function in maintaining social cohesion and well-being in higher social animals" (Adler 2002: 885). This "mutually responsive physiologic engagement" brings into play the "close links uniting social phenomena to the biological phenomena from which they immediately derive" (Solvay 1906: 26).
Interpersonal physiology
Furthermore, sociophysiology explores the "intimate relationship and mutual regulation between social and physiological systems that is especially vital in human groups" (Barchas 1986: 210). In other words, sociophysiology studies the "physio- and psycho-energetic phenomena at the basis of social groupings" (Solvay 1906: 25). Along these lines, Zeliony (1912) noted that
In addition, sociophysiology "describes structure-function relationships for body structures and interactive functions relevant to psychiatric illness" (Gardner 1997: 351), and also "assumes that psychiatric disorders are pathological variants of the motivation, emotions, and conflict involved in normal communicational processes" (Gardner and Price 1999: 247–248). Psychiatry, thus, involves the diagnosis and treatment of what Lilienfeld (1879: 280) termed "physiological social pathology", and may be classed as a subfield of sociophysiology, called "pathological sociophysiology" by Zeliony (1912: 405). As summarized by Ellwood (1916), Zeliony thought that, in the future,
Ellwood (1916: 298) also noted that Zeliony's future sociophysiology, being a natural biological science, must be Darwinian.
In short, sociophysiology is "reciprocal, interpersonal physiology" (Adler 2002: 885). Such interpersonal physiology may have implications in the realm of human politics. For example, the findings of a recent study "suggest that political attitudes vary with physiological traits linked to divergent manners of experiencing and processing environmental threats" (Oxley et al. 2008: 1669).
Notes and references
Notes
References
Adler, H. M. (2002). The sociophysiology of caring in the doctor–patient relationship. Journal of General Internal Medicine, vol. 17, no. 11, pp. 883–890.
Barchas, P. R. (1986). A sociophysiological orientation to small groups. In E. J. Lawler, ed., Advances in Group Processes, vol. 3, pp. 209–246. Greenwich, CT: JAI Press.
Di Mascio, A., Boyd, R. W., Greenblatt, M., and H. C. Solomon. (1955). The psychiatric interview (a sociophysiologic study). Diseases of the Nervous System, vol. 16, no. 1, pp. 4–9.
Ellwood, C. A. (1916). Objectivism in sociology. American Journal of Sociology, vol. 22, no. 3, pp. 289–305.
Freund, P. E. S. (1988). Bringing society into the body: Understanding socialized human nature. Theory and Society, vol. 17, no. 6, pp. 839–864.
Gardner Jr., R. J. (1997). Sociophysiology as the basic science of psychiatry. Theoretical Medicine, vol. 18, no. 4, pp. 335–356.
Gardner Jr., R. J., and J. S. Price. (1999). Sociophysiology and depression. In T. E. Joiner and J. C. Coyne, eds., The Interactional Nature of Depression: Advances in Interpersonal Approaches. Washington, DC: American Psychological Association.
Lilienfeld, P. (1879). Die sociale Physiologie. Volume 4 of Gedanken über die Socialwissenschaft der Zukunft. Mitau: E. Behre's Verlag.
Mauss, M. (1936). Les techniques du corps. Journal de Psychologie, vol. 32, nos. 3–4, 15 mars – 15 avril 1936. Reprinted in M. Mauss, Sociologie et anthropologie, Paris: PUF, 1950, pp. xxx-xxx.
Oxley, D. R. et al. (2008). Political attitudes vary with physiological traits. Science 19 September 2008: Vol. 321. no. 5896, pp. 1667–1670.
Solvay, E. (1906). Note sur des formules d’introduction à l’énergétique physio- et psycho-sociologique. Fascicule 1 des Notes et Mémoires de l’Institut de Sociologie, Instituts Solvay, Parc Léopold, Bruxelles. Bruxelles et Leipzig: Misch et Thron.
Waxweiler, E. (1906). Esquisse d’une sociologie. Fascicule 2 des Notes et Mémoires de l’Institut de Sociologie, Instituts Solvay, Parc Léopold, Bruxelles. Bruxelles et Leipzig: Misch et Thron.
Zeliony, G. P. (1912). Über die zukünftige Soziophysiologie. Archiv für Rassen- und Gesellschafts-Biologie, vol. 9, no. 4, pp. 405–429.
Further reading
Barchas, P. R., ed. (1984). Social Hierarchies: Essays Toward a Sociophysiological Perspective. Westport, CT: Greenwood.
Barchas, P. R. and S. P. Mendoza, eds. (1984). Social Cohesion: Essays Toward a Sociophysiological Perspective. Westport, CT: Greenwood.
Buytendijk, F. J. (1974). Prolegomena to an Anthropological Physiology. Pittsburgh: Duquesne University Press.
Gardner Jr., R. J. and D. R. Wilson. (2004). Sociophysiology and evolutionary aspects of psychiatry. In J. Panksepp, ed., Textbook of Biological Psychiatry. Wiley.
Mysterud, I. (2004). One name for the evolutionary baby? A preliminary guide for everyone confused by the chaos of names. Social Science Information, vol. 43, no. 1, pp. 95–114.
Perec, G. (1976) Lire: esquisse socio-physiologique. Esprit, no. 453, pp. 9–20. Reprinted in G. Perec, Penser/Classer, Paris: Hachette, 1985.
Reinheimer, H. (1920). Symbiosis: A Socio-physiological Study of Evolution. London: Headley Brothers. (Reinheimer seems to use the term "socio-physiology" as a synonym for "eugenics," which usage differs vastly from that of other writers, both early and late.)
Waid, W. M., ed. (1984). Sociophysiology. New York: Springer Verlag.
See also
Biological psychology
Ethology
Physiological psychology
Psychophysiology
Social interaction
Social psychology
Sociobiology
G. P. Zeliony
External links
Biozentrum Universität Würzburg: Research: Behavioral Physiology and Sociobiology.
Universität Bayreuth, Studies on behavioural ecology and sociophysiology in European rabbits.
Hominisation-Anton Fürlinger, Social Brain and Sociophysiology.
The Institute of Sociophysiology takes a pataphysical approach to the subject.
Behavioural sciences
Ethology
Sociobiology
Physiology | Sociophysiology | [
"Biology"
] | 1,895 | [
"Behavior",
"Physiology",
"Behavioural sciences",
"Sociobiology",
"Ethology"
] |
12,010,723 | https://en.wikipedia.org/wiki/Ra%C3%ABlian%20beliefs%20and%20practices | Raëlian beliefs and practices are the concepts and principles of Raëlism, a new religious movement and UFO religion founded in 1974 by Claude Vorilhon, an auto racing journalist who changed his name to "Raël". The followers of the International Raëlian Movement believe in an advanced species of extraterrestrial aliens called Elohim who created life on Earth. Raëlians are individualists who believe in sexual self-determination. As advocates of the universal ethic and world peace, they believe the world would be better if geniuses had an exclusive right to govern in what Rael terms Geniocracy. As believers of life in outer space, they hope that human scientists will follow the path of the Elohim by achieving space travel through the cosmos and creating life on other planets. As believers in the resurrection of Jesus through a scientific cloning process (which includes memory transfer) by the Elohim, they encourage scientific research to extend life through cloning; however, critics outside are doubtful of its possibility.
Active followers of Raëlianism have exhibited their sex-positive feminism and pacifism through outdoor contacts such as parades. The major initiation rite in the Raëlian Church is the baptism or Transmission of the Cellular Plan and is enacted by upper-level members in the Raëlian clergy known as guides.
Beliefs
Structure of the Universe
Raël says that "everything is in everything". He says that, inside the atoms of living things, are living things that are made of atoms, which themselves contain living things that are made of atoms, and so on, to the infinitely small. The universe itself is contained in an atom inside of another universe, and so on, to the infinitely large. Because of the difference of mass, the activity of life inside of a living thing's atoms would undergo many millennia before enough time passes for that living thing to take a single step. Raëlians believe that the universe is infinite, and thus lacks a center. Because of this, one could not imagine where an ethereal soul would go, due to the universe's infinite nature. They believe that infinity exists in time as well as in space, for all levels of life. Some of critics believe that rationally it is not possible to connect the chain to infinity, and finally this chain must lead somewhere.
Raëlians believe that humanity would be able to create life on other planets only if humanity is peaceful enough to stop war. In that case, humanity could travel the distances between stars and create life on another planet. Progress in terraforming, molecular biology, and cloning would enable these teams to create continents and life from scratch. Progress in social engineering would ensure that this creation would have a better chance of both surviving and having the potential to understand its creators. Research on how civilization would occur on another planet would allow scientists to decide what traces of their origin should be left behind so that their role in life creation would someday be revealed. The progress achieved by the science teams would ultimately sustain a perpetual chain of life.
Intelligent Design
Creation of life on Earth by extraterrestrials
In his book The Message Given to me by Extraterrestrials (now republished as Intelligent Design: Message from the Designers 2006 ), Vorilhon claims that on 13 December 1973, he found a spacecraft shaped like a flattened bell that landed inside Puy de Lassolas, a volcano near the capital city of Auvergne. A 25,000-year-old human-like extraterrestrial inside the spacecraft named Yahweh said that Elohim was the name that primitive people of Earth called members of his extraterrestrial race, who were seen as "those who came from the sky". Yahweh explained that Earth was originally void of land, but the Elohim came, broke apart the clouds, exposed the seas to sunlight, built a continent, and synthesized a global ecosystem. Solar astronomy, terraformation, nanotechnology, and genetic engineering allowed Elohim to adapt life to Earth's thermal and chemical makeup.
Yahweh gave materialistic explanations of the Garden of Eden, a large laboratory that was based on an artificially constructed continent; Noah's Ark, a spaceship that preserved DNA that was used to resurrect animals through cloning; the Tower of Babel, a rocket that was supposed to reach the creators' planet; and the Great Flood, the byproduct of a nuclear missile explosion that the Elohim sent. After tidal wave floods following the explosions receded, Elohim scattered the Israelites and had them speak the language of other tribes.
According to Vorilhon, Elohim contacted about forty people to act as their prophets on Earth, including Moses, Elijah, Ezekiel, Buddha,
John the Baptist, Jesus,
Muhammad, and Joseph Smith. The religions thought to be from Elohimic origins include Judaism, Buddhism, Christianity, Islam, and Mormonism.
According to Vorilhon, multiple religious texts indicate that the Elohim would return at the age of Apocalypse or Revelation (unveiling of the truth). Humans from another world would appear to drop down from the sky, and meet in the embassy that they have asked Raël to build for them, and share their advanced scientific knowledge with humanity. Thus, one of the stated main goals of the Raëlian movement is to inform as many people as possible about this extraterrestrial race.
The controversy surrounding the origins of Raelian beliefs centers on the writings of several authors in the late 1960s. Jean Sendy, a French writer, translator, and author of books on the esoteric and UFOs wrote several novels detailing the creation of Earth by extraterrestrials. One of the best known researchers in this field is Erich von Däniken, the 'father' of the Ancient Astronauts theory, which postulates that Earth might have been visited by extraterrestrials in the remote past.
With the publication of Chariots of the Gods? in 1968, Erich von Däniken introduced the intervention theory to the general public. Von Däniken wrote that the technologies and religions of ancient civilizations were granted by extraterrestrials worshiped as gods. Von Däniken argued that only extraterrestrial intervention can explain the higher technological knowledge presumed to be essential for the production of ancient artifacts such as the Egyptian pyramids, Stonehenge and the Moai of Easter Island. Humans in ancient times considered this extraterrestrial high-tech to be supernatural and the aliens themselves to be 'gods'. One can find direct parallels to the messages that Vorilhon claimed to have received and written about in his books. Marie-Hélène Parent, ex-guide Raëlian priest, describes Sendy and Vorilhon meeting several times for drinks and conversation throughout the years of 1973 and 1974, prior to Vorilhon's claimed extraterrestrial encounter.
Humanity's chance of creating life on other planets
Raëlians believe that humanity would be able to create life on other planets only if it is peaceful enough to stop war. If done, humanity could travel the distances between stars and create life on another planet. Progress in terraformation, molecular biology, and cloning would enable these teams to create continents and life from scratch. Progress in social engineering would ensure that this creation would have a better chance of both surviving as well as having the potential to understand its creators. Research on how globalization would occur on another planet would allow scientists to decide what traces of their origin should be left behind so that their role in life creation would someday be revealed. The progress achieved by the science teams would ultimately sustain a perpetual chain of life.
A coming judgement
Raëlians do not believe in reincarnation as dictated by mystical writings because they do not believe that an ethereal soul exists free of physical confinement. Instead the Raëlians think that advanced supercomputers of the Elohim are right now recording the memories and DNA of human beings. When Elohim release this information for the coming resurrection, people would be brought back from the dead and the judgments upon them would be realized based on actions in their past life. People excluded from physical recreation would include those who achieved nothing positive but were not evil. Vorilhon expressed an interest in cloning Hitler for war trials and retroactive punishment. Raël also mentioned cloning as the solution to terrorism by suicide attacks, as the perpetrators would not be able to escape punishment by killing themselves if the Elohim recreated them after their attacks.
Practices
Initiation of new members
The major initiation rite in the Raëlian Church is the "baptism" or "transmission of the cellular plan". That rite is enacted by upper-level members of the Raëlian clergy who are called "guides". Canadian sociologist Susan J. Palmer says that in 1979, Raël introduced the "Act of Apostasy" as an obligation for people who are preparing for their Raëlian baptism. CTV Television Network states that apostasy from other religions is required for new Raëlian members. Joining the Raëlian Church through transmission of the cellular plan happens only on certain days of the year. There are four of such days, all of which mark anniversaries in the Raëlian calendar.
The Raëlian baptism is known as "transmission of the cellular plan", where "cellular" refers to the organic cells of the body, and the "plan" refers to the genetic makeup of the individual. That Raëlian baptism involves a guide member laying water onto the forehead of the new member. That practice began on "the first Sunday in April" of 1976, when Raël baptized 40 Raëlians. Raëlians believe that their genetic information is recorded by a remote computer, and would become recognized during their final hour, when they will be judged by the extraterrestrial Elohim.
There is continuing debate on whether Raëlians can be identified as a cult. The government of France classifies the Raelian Movement as a "secte" (French word for cult). However, according to Glenn McGee, the associate director of the Center for Bioethics at the University of Virginia, part of the sect is a cult, while the other part is a commercial website that collects large sums of money from people who are interested in human cloning. The Bureau of Democracy, Human Rights, and Labor of the United States Department of State, and sociologist Susan J. Palmer, have classified the International Raëlian Movement as a religion.
Activism
Raëlians routinely advocate sex-positive feminism and genetically modified food and actively protest against wars in addition to the Catholic Church. For example, a photographer of the Associated Press snapped a picture of half-naked Raëlian women wearing pasties as part of an anti-war demonstration in Seoul, Korea. A snapshot by Agence France-Presse revealed Raëlians in white alien costumes with signs bearing the message "NO WAR ... ET wants Peace, too!". On 6 August 2003, the first day of Raëlian year 58 AH, a tech article on the USA Today newspaper mentions an "unlikely ally" of the Monsanto Company, the Raëlian Movement of Brazil. The movement gave vocal support in response to the company's support for genetically modified organisms particularly in their country. Brazilian farmers have been using Monsanto's genetically engineered soy plant as well as the glyphosate herbicide to which it was artificially adapted. The Raëlians spoke against the Brazilian government's ban on GMOs.
In July 2001, Raëlians on the streets attracted Italians and Swiss people as they gave leaflets in protest to over a hundred child molesters in existence among Roman Catholic clergy in France. They recommended that parents should not send their children to Catholic confession. The Episcopal vicar of Geneva sued the Raëlian Church for libel but did not win. The judge did not accept the charges for the reason that the Raëlians were not attacking the whole of the Catholic Church.
In October 2002, Raëlians in a Canadian anti-clerical parade held handed out Christian crosses to high school students. They were invited to burn the crosses in a park not far from Montreal's Mount Royal and to sign letters of apostasy from the Roman Catholic Church. The Quebec Association of Bishops called this "incitement to hatred", and several school boards attempted to prevent their students from meeting Raëlians.
Topless Rights of Women
Several Raëlian groups in the United States have organized annual protests, based upon their claim that women should have the same legal right to go topless in public, which men can do without fear of arrest for indecent exposure. Some people have called that a publicity stunt that serves to recruit new members. "Go Topless Day" is their annual event, in which women protest while topless, except for nipple pasties to avoid arrest. That event is held near August 26th, which is the anniversary of the day that women were given the right to vote in the USA.
Advocacy
Embassy for Extraterrestrials
Raëlians believe that life on earth—as well as many religions of the world—was the work of extraterrestrial influence. They believe these were scientists and that ancient people saw them as "gods" and gave the name "Elohim". Raëlians believe that the Embassy for Extraterrestrials or "Third Temple" is to support an official contact with Extraterrestrial Elohim and their messengers of the main religions at the "New Jerusalem". Writers who have influenced Raëlian beliefs include Zechariah Sitchin and Erich von Däniken.
The International Raëlian Movement envisions having an entrance with an aseptic chamber leading to a conference room for twenty-one people as well as a dining room of the same capacity. In the plan are seven rooms for the purpose of receiving human guests into the embassy. The embassy building, along with the swimming pool, would be in the center of a large park and protected from trespassing by a wall−a maximum of two stories-to surround the entire complex's circumference. Trees and bushes are to be planted in the outskirts of the wall's area. The walls are to have a northern and southern entrance. The landing pad for the embassy should be able to fit a spaceship of twelve meters of diameter or 39'4" on its terrace. The terrace is to be above the rooms in the torus, which are for extraterrestrials only. The seven rooms directly underneath the landing pad would be protected from occupants of other rooms with a thick metal door. Finally, the International Raëlian Movement wants to avoid military and radar surveillance of the airspace above the embassy. Buildings for administration, food and water provisions, and state-of-the-art sanitation and communication systems are part of this vision. A nearby replica of the Raëlian Embassy for Extraterrestrials open to the public is expected to show visitors what it is like inside the real one.
In February 1991, the Raëlian Church modified their symbol to remove the swastika to help in negotiations with building the "Third Temple of Israel". The official reason given was a telepathic request from extraterrestrials called Elohim to change the symbol in order to help in negotiations with Israel for the building of a Raëlian "embassy" or "third temple of Israel" to greet the anticipated coming of extraterrestrials and founders of past religions, although the country still denies their request.
On 13 December 1997, the leader of the International Raëlian Movement had decided to extend the possibility of building the embassy outside of Jerusalem and also allow that a significant portion of the embassy property be covered with water. The area of the proposed embassy property is still envisioned at a minimum of 3.47 square kilometers, with a radius of at least 1.05 kilometers.
In 2005, the Israeli Raëlian Guide Kobi Drori stated that the Lebanese government was discussing proposals by the Raëlian movement to build their "interplanetary embassy" in Lebanon. However, one condition was that the Raëlians did not display their logo on top of the building because it mixes a swastika and a Star of David. According to Drori, the Raëlians involved declined this offer, as they wished to keep the symbol as is.
Ideas of how government and the economy should run
According to the book Geniocracy, creating a peaceful worldwide political union requires a form of government that favors intelligence over mediocrity. While having a democratic electoral apparatus, it differs from traditional liberal democracy by requiring members of the electorate to meet a minimum standard of intelligence. The thresholds proposed by the Raëlians are 50% above average for a candidate and 10% above average for a voter. Raëlians believe that a world government is only possible through establishing a global currency, a common language, and a transformation of militaries of the world into civil police.
In Raël's book, Extraterrestrials took me to their Planet, Raël claims that an extraterrestrial gave him the idea of Humanitarianism. Under the establishment of Humanitarianism, people would not have ownership of businesses or exploitable goods created by others. Instead, people would rent each of them for a period of 49 years. The founders would be able to receive the rents for up to 49 years or when they die, whichever is later. Any rents not inherited by relatives after 49 years would go to the State. By balancing inheritances, children would be born with enough financial means to forsake menial tasks for endeavors that may benefit the whole of humanity. Family houses could be inherited from generation to generation, free of rent.
In his much later book, Maitreya, Raël says that the road to a world without money is capitalism and globalization, as opposed to communism. Capitalism would allow people who contribute much to society to also contribute to its scientific and technological development. Under capitalism, society would produce as much money as it can. The money would become important in the short run, as nanotechnology quickly lowers the cost of goods while putting many people out of work.
An anti-cult organization called Info-Cult argued that Geniocracy was a fascist ideology. However, Geniocracy is not a political party, because it allows for differing ideologies.
Liberal sensuality
According to Vorilhon's book Sensual Meditation, one should develop the ability to break free of habitual thoughts that prevent one from appreciating everyday phenomena. The book describes in detail six different meditations involving making full use of the lungs' capacity to expand and contract, oxygenating the blood and the cells within, imagining heat travelling upwards from toe to the head, allowing the skin to feel under itself, and experiencing touch with another person's body and examining their figure.
According to the book Maitreya by Vorilhon, love involves experiencing different varieties and possibilities that allow one to break habits in order to make life more pleasant and interesting and that it is the only thing that can stop war and injustice that persists in today's world. Raëlians believe in the right to form new religions or new political parties as long as they do not promote violence. As individualists, Raëlians believe that the one who gives the order to harm others is less at fault than the one who executes it.
Raëlians say they encourage adult homosexual, bisexual, and heterosexual relationships and that society should recognize them legally. However, government authorities such as those in Switzerland fear that Raëlians are a threat to public morals for supporting liberalized sex education for children. The authorities believe that such liberalized sex education teaches youth how to obtain sexual gratification which would encourage sexual abuse of underage children. The Raëlians disagree with those fears and stated that sex education done properly would involve educating parents as well as children.
Susan J. Palmer writes that in 1991, a French journalist went to a Raëlian Seminar and taped couples having sexual intercourse in tents. These tapes gained widespread publicity—with news stories describing these practices as perverted and a form of brainwashing.
Since 1991, Raël's teachings on sexual intercourse have caused controversy among other religious groups. The next year, Catholic schools in Montreal, Canada objected to a proposed condom vending machine as contrary to their mission. In response, Raëlian guides gave the Catholic students ten thousand condoms. The Commissioner of Catholic schools for Montreal said they could do nothing to stop them. Around this time, Raëlians dubbed the event "Operation Condom".
Cloning of humans
In the scientific community, reproductive cloning refers only to the creation of a genetically identical living thing. "Genetically identical" does not mean altogether identical; this kind of cloning does not reproduce a living thing's memories or experiences, for example. However, in discussions of Raëlianism, cloning sometimes seems to refer not only to reproductive cloning, but also reproductive human cloning plus mind and/or brain transfer, or to a process of making adult clones. Raëlians take this even further and say that humanity can attain eternal life through the science of cloning.
According to the book Yes to Human Cloning, the first stage of this extended cloning process is creating a human embryo through human cloning. Raëlian bishop and Clonaid CEO Brigitte Boisselier claimed that an American woman underwent a cloning procedure of this type that led to the birth of a girl named Eve on 26 December 2002. Vorilhon told lawmakers that banning the development of human cloning was comparable to outlawing medical advances such as "antibiotics, blood transfusions, and vaccines."
The second stage of cloning, according to Raëlians, is causing the clone to mature faster than normal. Raël says that in the future, scientists will discover an "accelerated-growth process" in which a process like guided self-assembly of rapidly expanded cells or even nanotechnological assembly of a whole human body can form in a very short time.
The third stage is the transfer of memory and personality from the original person to the mature clone. For the process to maintain one branch for personality and memory, as opposed to two, a recording of the individual's mind would be required before the time of death, and would be transferred to an adult clone body after the original has died.
In the final stages of development, hitherto unknown information contained within undamaged DNA would be enough to bring others back from the dead including their memories and personality. This would be done by taking a small sample from someone's body and preserving it at the time when the level of the brain's efficiency and knowledge is highest. On the day of death, a cell would be taken from the sample for the cloning to take place, and the memories and personality would be restored to their peak level.
The Raëlian Church has close links with the controversial company Clonaid. Brigitte Boisselier, a Raëlian and chief executive of Clonaid, made a controversial and unverified claim that a human baby was conceived through cloning technology. Around this time, Clonaid's subsidiary BioFusion Tech claimed to have in possession a cell fusion device that assisted the cloning of human embryos. The Vatican, however, says that experimenters expressed "brutal mentality" for attempting to clone human beings. Pope John Paul II criticized the experiment which he believed threatened the dignity of human life. In response, the leader of the Raëlian Church dismissed the Pope's ethical concerns, calling them an "accumulation of religious prejudices."
See also
Geniocracy
History of Raëlism
Raëlism
Biogenesis
Exotheology
Directed Panspermia
Brigitte Boisselier – French CEO of Clonaid
Claude Vorilhon/Raël – French singer, guitarist, and former automobile journalist
Glenn Carter – British singer, actor
Nayah – French singer
References
Cited texts
Raël, Geniocracy. The Raëlian Foundation, 2004.
Raël, Intelligent Design. Nova Distribution, 2006. .
Raël, Maitreya. The Raëlian Foundation, 2003.
Raël, Sensual Meditation. Tagman Press, 2001.
Raël, Yes to Human Cloning: Immortality Thanks to Science. Tagman Press, 2001. .
Further reading
The 2005 novel The Possibility of an Island – (translated by Gavin Bowd, original title La Possibilité d'une île) by the French writer, Michel Houellebecq is seen by reviewers as a description of Raëlism in the future.
Raël, La géniocratie . L'Edition du message, 1977. .
External links
Who are the Raëlians? David Chazan, BBC News 2002.
The Raëlian books compared to Jean Sendy's
Testimonies by ex-Raelians Site by former Raelian.
Intelligent design | Raëlian beliefs and practices | [
"Engineering"
] | 5,061 | [
"Intelligent design",
"Design"
] |
12,010,787 | https://en.wikipedia.org/wiki/Magnetorotational%20instability | The magnetorotational instability (MRI) is a fluid instability that causes an accretion disk orbiting a massive central object to become turbulent. It arises when the angular velocity of a conducting fluid in a magnetic field decreases as the distance from the rotation center increases. It is also known as the Velikhov–Chandrasekhar instability or Balbus–Hawley instability in the literature, not to be confused with the electrothermal Velikhov instability. The MRI is of particular relevance in astrophysics where it is an important part of the dynamics in accretion disks.
Gases or liquids containing mobile electrical charges are subject to the influence of a magnetic field. In addition to hydrodynamical forces such as pressure and gravity, an element of magnetized fluid also feels the Lorentz force where is the current density and is the magnetic field vector. If the fluid is in a state of differential rotation about a fixed origin, this Lorentz force can be surprisingly disruptive, even if the magnetic field is very weak. In particular, if the angular velocity of rotation decreases with radial distance the motion is unstable: a fluid element undergoing a small displacement from circular motion experiences a destabilizing force that increases at a rate which is itself proportional to the displacement. This process is known as the Magnetorotational Instability, or "MRI".
In astrophysical settings, differentially rotating systems are very common and magnetic fields are ubiquitous. In particular, thin disks of gas are often found around forming stars or in binary star systems, where they are known as accretion disks. Accretion disks are also commonly present in the centre of galaxies, and in some cases can be extremely luminous: quasars, for example, are thought to originate from a gaseous disk surrounding a very massive black hole. Our modern understanding of the MRI arose from attempts to understand the behavior of accretion disks in the presence of magnetic fields; it is now understood that the MRI is likely to occur in a very wide variety of different systems.
Discovery
The MRI was first noticed in a non-astrophysical context by Evgeny Velikhov in 1959 when considering the stability of Couette flow of an ideal hydromagnetic fluid. His result was later generalized by Subrahmanyan Chandrasekhar in 1960. This mechanism was proposed by David Acheson and Raymond Hide (1973) to perhaps play a role in the context of the Earth's geodynamo problem. Although there was some follow-up work in later decades (Fricke, 1969; Acheson and Hide 1972; Acheson and Gibbons 1978), the generality and power of the instability were not fully appreciated until 1991, when Steven A. Balbus and John F. Hawley gave a relatively simple elucidation and physical explanation of this important process.
Physical process
In a magnetized, perfectly conducting fluid, the magnetic forces behave in some very important respects as though the elements of fluid were connected with elastic bands: trying to displace such an element perpendicular to a magnetic line of force causes an attractive force proportional to the displacement, like a spring under tension. Normally, such a force is restoring, a strongly stabilizing influence that would allow a type of magnetic wave to propagate. If the fluid medium is not stationary but rotating, however, attractive forces can actually be destabilizing. The MRI is a consequence of this surprising behavior.
Consider, for example, two masses, mi ("inner") and mo ("outer") connected by a spring under tension, both masses in orbit around a central body, Mc. In such a system, the angular velocity of circular orbits near the center is greater than the angular velocity of orbits farther from the center, but the angular momentum of the inner orbits is smaller than that of the outer orbits. If mi is allowed to orbit a little bit closer to the center than mo, it will have a slightly higher angular velocity. The connecting spring will pull back on mi, and drag mo forward. This means that mi experiences a retarding torque, loses angular momentum, and must fall inward to an orbit of smaller radius, corresponding to a smaller angular momentum. mo, on the other hand, experiences a positive torque, acquires more angular momentum, and moves outward to a higher orbit. The spring stretches yet more, the torques become yet larger, and the motion is unstable! Because magnetic forces act like a spring under tension connecting fluid elements, the behavior of a magnetized fluid is almost exactly analogous to this simple mechanical system. This is the essence of the MRI .
A more detailed explanation
To see this unstable behavior more quantitatively, consider the equations of motion for a fluid element mass in circular motion with an angular velocity In general will be a function of the distance from the rotation axis and we assume that the orbital radius is The centripetal acceleration required to keep the mass in orbit is ; the minus sign indicates a direction toward the center. If this force is gravity from a point mass at the center, then the centripetal acceleration is simply where is the gravitational constant and is the central mass.
Let us now consider small departures from the circular motion of the orbiting mass element caused by some perturbing force. We transform variables into a rotating frame moving with the orbiting mass element at angular velocity with origin located at the unperturbed, orbiting location of the mass element. As usual when working in a rotating frame, we need to add to the equations of motion a Coriolis force plus a centrifugal force The velocity is the velocity as measured in the rotating frame. Furthermore, we restrict our attention to a small neighborhood near say with much smaller than Then the sum of the centrifugal and centripetal forces is
to linear order in With our axis pointing radial outward from the unperturbed location of the fluid element and our axis pointing in the direction of increasing azimuthal angle (the direction of the unperturbed orbit), the and equations of motion for a small departure from a circular orbit are:
where and are the forces per unit mass in the and directions, and a dot indicates a time derivative (i.e., is the velocity, is the acceleration, etc.). Provided that and are either 0 or linear in x and y, this is a system of coupled second-order linear differential equations that can be solved analytically.
In the absence of external forces, and , the equations of motion have solutions with the time dependence where the angular frequency satisfies the equation
where is known as the epicyclic frequency. In our solar system, for example, deviations from a sun-centered circular orbit that are familiar ellipses when viewed by an external viewer at rest, appear instead as small radial and azimuthal oscillations of the orbiting element when viewed by an observer moving with the undisturbed circular motion.
These oscillations trace out a small retrograde ellipse (i.e. rotating in the opposite sense of the large circular orbit), centered on the undisturbed orbital location of the mass element.
The epicyclic frequency may equivalently be written which shows that it is proportional to the radial derivative of the angular momentum per unit mass, or specific angular momentum. The specific angular momentum must increase outward if stable epicyclic oscillations are to exist, otherwise displacements would grow exponentially, corresponding to instability. This is a very general result known as the Rayleigh criterion (Chandrasekhar 1961) for stability. For orbits around a point mass, the specific angular momentum is proportional to so the Rayleigh criterion is well satisfied.
Consider next the solutions to the equations of motion if the mass element is subjected to an external restoring force, where is an arbitrary constant (the "spring constant"). If we now seek solutions for the modal displacements in and with time dependence we find a much more complex equation for
Even though the spring exerts an attractive force, it may destabilize. For example, if the spring constant is sufficiently weak, the dominant balance will be between the final two terms on the left side of the equation. Then, a decreasing outward angular velocity profile will produce negative values for and both positive and negative imaginary values for The negative imaginary root results not in oscillations, but in exponential growth of very small displacements. A weak spring therefore causes the type of instability described qualitatively at the end of the previous section. A strong spring on the other hand, will produce oscillations, as one intuitively expects.
The spring-like nature of magnetic fields
The conditions inside a perfectly conducting fluid in motion is often a good approximation to astrophysical gases. In the presence of a magnetic field a moving conductor responds by trying to eliminate the Lorentz force on the free charges. The magnetic force acts in such a way as to locally rearrange these charges to produce an internal electric field of In this way, the direct Lorentz force on the charges vanishes. (Alternatively, the electric field in the local rest frame of the moving charges vanishes.) This induced electric field can now itself induce further changes in the magnetic field according to Faraday's law,
Another way to write this equation is that if in time the fluid makes a displacement then the magnetic field changes by
The equation of a magnetic field in a perfect conductor in motion has a special property: the combination of Faraday induction and zero Lorentz force makes the field lines behave as though they were painted, or "frozen," into the fluid. In particular, if is initially nearly constant and is a divergence-free displacement, then our equation reduces to
because of the vector calculus identity
Out of these 4 terms, is one of Maxwell's equations. By the divergence-free assumption, . because B is assumed to be nearly constant. Equation shows that changes only when there is a shearing displacement along the field line.
To understand the MRI, it is sufficient to consider the case in which is uniform in vertical direction, and varies as Then
where it is understood that the real part of this equation expresses its physical content. (If is proportional to for example, then is proportional to )
A magnetic field exerts a force per unit volume on an electrically neutral, conducting fluid equal to Ampere's circuital law gives because Maxwell's correction is neglected in the MHD approximation. The force per unit volume becomes
where we have used the same vector calculus identity. This equation is fully general, and makes no assumptions about the strength or direction of the magnetic field.
The first term on the right is analogous to a pressure gradient. In our problem it may be neglected because it exerts no force in the plane of the disk, perpendicular to The second term acts like a magnetic tension force, analogous to a taut string. For a small disturbance it exerts an acceleration given by force divided by mass, or equivalently, force per unit volume divided by mass per unit volume:
Thus, a magnetic tension force gives rise to a return force which is directly proportional to the displacement. This means that the oscillation frequency for small displacements in the plane of rotation of a disk with a uniform magnetic field in the vertical direction satisfies an equation ("dispersion relation") exactly analogous to equation , with the "spring constant"
As before, if there is an exponentially growing root of this equation for wavenumbers satisfying
This corresponds to the MRI.
Notice that the magnetic field appears in equation only as the product Thus, even if is very small, for very large wavenumbers this magnetic tension can be important. This is why the MRI is so sensitive to even very weak magnetic fields: their effect is amplified by multiplication by Moreover, it can be shown that MRI is present regardless of the magnetic field geometry, as long as the field is not too strong.
In astrophysics, one is generally interested in the case for which the disk is supported by rotation against the gravitational attraction of a central mass. A balance between the Newtonian gravitational force and the radial centripetal force immediately gives
where is the Newtonian gravitational constant, is the central mass, and is radial location in the disk. Since this so-called Keplerian disk is unstable to the MRI . Without a weak magnetic field, the flow would be stable.
For a Keplerian disk, the maximum growth rate is which occurs at a wavenumber satisfying
is very rapid, corresponding to an amplification factor of more than 100 per rotation period.
The nonlinear development of the MRI into fully developed turbulence may be followed via large scale numerical computation.
Applications and laboratory experiments
Interest in the MRI is based on the fact that it appears to give an explanation for the origin of turbulent flow in astrophysical accretion disks (Balbus and Hawley, 1991).
A promising model for the compact, intense X-ray sources discovered in the 1960s was that of a neutron star or black hole drawing in ("accreting") gas from its surroundings (Prendergast and Burbidge, 1968). Such gas always accretes with a finite amount of angular momentum relative to the central object, and so it must first form a rotating disk — it cannot accrete directly onto the object without first losing its angular momentum. But how an element of gaseous fluid managed to lose its angular momentum and spiral onto the central object was not at all obvious.
One explanation involved shear-driven turbulence (Shakura and Sunyaev, 1973). There would be significant shear in an accretion disk (gas closer to the centre rotates more rapidly than outer disk regions), and shear layers often break down into turbulent flow. The presence of shear-generated turbulence, in turn, produces the powerful torques needed to transport angular momentum from one (inner) fluid element to another (farther out).
The breakdown of shear layers into turbulence is routinely observed in flows with velocity gradients, but without systematic rotation. This is an important point, because rotation produces strongly stabilizing Coriolis forces, and this is precisely what occurs in accretion disks . As can be seen in equation , the K = 0 limit produces Coriolis-stabilized oscillations, not exponential growth. These oscillations are present under much more general conditions as well: a recent laboratory experiment (Ji et al., 2006) has shown stability of the flow profile expected in accretion disks under conditions in which otherwise troublesome dissipation effects are (by a standard measure known as the Reynolds number) well below one part in a million. All of this changes, however, are when even a very weak magnetic field is present. The MRI produces torques that are not stabilized by Coriolis forces. Large scale numerical simulations of the MRI indicate that the rotational disk flow breaks down into turbulence (Hawley et al., 1995), with strongly enhanced angular momentum transport properties. This is just what is required for the accretion disk model to work. The formation of stars (Stone et al., 2000), the production of X-rays in neutron star and black hole systems (Blaes, 2004), and the creation of active galactic nuclei (Krolik, 1999) and gamma ray bursts (Wheeler, 2004) are all thought to involve the development of the MRI at some level.
Thus far, we have focused rather exclusively on the dynamical breakdown of laminar flow into turbulence triggered by a weak magnetic field, but it is also the case that the resulting highly agitated flow can act back on this same magnetic field. Embedded magnetic field lines are stretched by the turbulent flow, and it is possible that systematic field amplification could result. The process by which fluid motions are converted to magnetic field energy is known as a dynamo (Moffatt, 1978); the two best studied examples are the Earth's liquid outer core and the layers close to the surface of the Sun. Dynamo activity in these regions is thought to be responsible for maintaining the terrestrial and solar magnetic fields. In both of these cases thermal convection is likely to be the primary energy source, though in the case of the Sun differential rotation may also play an important role. Whether the MRI is an efficient dynamo process in accretion disks is currently an area of active research (Fromang and Papaloizou, 2007).
There may also be applications of the MRI outside of the classical accretion disk venue. Internal rotation in stars (Ogilvie, 2007), and even planetary dynamos (Petitdemange et al., 2008) may, under some circumstances, be vulnerable to the MRI in combination with convective instabilities. These studies are also ongoing.
Finally, the MRI can, in principle, be studied in the laboratory (Ji et al., 2001), though these experiments are very difficult to implement. A typical set-up involves either concentric spherical shells or coaxial cylindrical shells. Between (and confined by) the shells, there is a conducting liquid metal such as sodium or gallium. The inner and outer shells are set in rotation at different rates, and viscous torques compel the trapped liquid metal to differentially rotate. The experiment then investigates whether the differential rotation profile is stable or not in the presence of an applied magnetic field.
A claimed detection of the MRI in a spherical shell experiment (Sisan et al., 2004), in which the underlying state was itself turbulent, awaits confirmation at the time of this writing (2009). A magnetic instability that bears some similarity to the MRI can be excited if both vertical and azimuthal magnetic fields are present in the undisturbed state (Hollerbach and Rüdiger, 2005). This is sometimes referred to as the helical-MRI, (Liu et al., 2006) though its precise relation to the MRI described above has yet to be fully elucidated. Because it is less sensitive to stabilizing ohmic resistance than is the classical MRI, this helical magnetic instability is easier to excite in the laboratory, and there are indications that it may have been found (Stefani et al., 2006). The detection of the classical MRI in a hydrodynamically quiescent background state has yet to be achieved in the laboratory, however.
The spring-mass analogue of the standard MRI has been demonstrated in rotating Taylor–Couette / Keplerian-like flow (Hung et al. 2019).
References
Balbus, S. A., and Hawley, J. F. 1991, Astrophys. J., 376, 214
Blaes, O. M. 2004, in Physics Fundamentals of Luminous Accretion Disks Around Black Holes. Proc. LXXVIII of Les Houches Summer School, Chamonix, France, ed. F. Menard, G. Pelletier, V. Beskin, J. Dalibard, p. 137. Paris/Berlin: Springer
Chandrasekhar, S. 1961, Hydrodynamic and Hydromagnetic Instability, Oxford: Clarendon
Fricke, K. 1969, Astron. Astrophys., 1, 388
Fromang, S., and Papaloizou J. 2007, Astron. Astrophys., 476, 1113
Hawley, J. F., Gammie, C. F., and Balbus, S. A. 1995, Astrophys. J., 440, 742
Ji, H., Goodman, J., and Kageyama, A. 2001, MNRAS, 325, L1
Krolik, J. 1999, Active Galactic Nuclei, Princeton: Princeton Univ.
Moffatt, H. K. 1978, Magnetic Field Generation in Electrically Conducting Fluids. Cambridge: Cambridge Univ
Ogilvie G., 2007, in The Solar Tachocline. ed. D. Hughes, R. Rosner, N. Weiss, p. 299. Cambridge: Cambridge Univ.
Prendergast, K., and Burbidge, G. R. 1968, Astrophys. J. Lett., 151, L83
Shakura, N., and Sunyaev, R. A. 1973, Astron. Astrophys., 24, 337
Stone, J. M., Gammie, C. F., Balbus, S. A., and Hawley, J. F. 2000, in Protostars and Planets IV, ed. V.Mannings, A.Boss, and S.Russell, Space Science Reviews, p. 589. Tucson: U. Arizona
Velikhov, E. P. 1959, J. Exp. Theor. Phys. (USSR), 36, 1398
Wheeler, J. C. 2004, Advances in Space Research, 34, 12, 2744
Further reading
Fluid dynamics
Magnetohydrodynamics
Plasma instabilities | Magnetorotational instability | [
"Physics",
"Chemistry",
"Engineering"
] | 4,296 | [
"Physical phenomena",
"Magnetohydrodynamics",
"Chemical engineering",
"Plasma phenomena",
"Plasma instabilities",
"Piping",
"Fluid dynamics"
] |
12,012,158 | https://en.wikipedia.org/wiki/List%20of%20optimization%20software | Given a transformation between input and output values, described by a mathematical function, optimization deals with generating and selecting the best solution from some set of available alternatives, by systematically choosing input values from within an allowed set, computing the output of the function and recording the best output values found during the process. Many real-world problems can be modeled in this way. For example, the inputs could be design parameters for a motor, the output could be the power consumption. For another optimization, the inputs could be business choices and the output could be the profit obtained.
An optimization problem, (in this case a minimization problem), can be represented in the following way:
Given: a function f : A R from some set A to the real numbers
Search for: an element x0 in A such that f(x0) ≤ f(x) for all x in A.
In continuous optimization, A is some subset of the Euclidean space Rn, often specified by a set of constraints, equalities or inequalities that the members of A have to satisfy. In combinatorial optimization, A is some subset of a discrete space, like binary strings, permutations, or sets of integers.
The use of optimization software requires that the function f is defined in a suitable programming language and connected at compilation or run time to the optimization software. The optimization software will deliver input values in A, the software module realizing f will deliver the computed value f(x) and, in some cases, additional information about the function like derivatives.
In this manner, a clear separation of concerns is obtained: different optimization software modules can be easily tested on the same function f, or a given optimization software can be used for different functions f.
The following tables provide a list of notable optimization software organized according to license and business model type.
Free and open-source software
Applications
{| class="wikitable"
|-
! Name
! License
! Description
|-
| ADMB || BSD
| nonlinear optimization framework using automatic differentiation.
|-
| ASCEND || GPL
| mathematical modelling chemical process modelling system.
|-
| CUTEr || GPL
| testing environment for optimization and linear algebra solvers.
|-
| GNU Octave || GPL
| software package using a high-level programming language, primarily intended for numerical computations; it is mostly compatible with MATLAB.
|-
| Scilab || CeCILL
| cross-platform numerical computational package and a high-level, numerically oriented programming language with a numerical optimization framework.
|}
Software libraries
{| class="wikitable"
|-
! Name
! License
! Description
|-
| ALGLIB || GPL
| dual licensed (GPL/commercial) optimization library (LP, QP and nonlinear programming problems), optionally using automatic differentiation. Cross-language: C++, C#.
|-
| COIN-OR || EPL 1.0
| integer programming, linear programming, nonlinear programming.
|-
| Dlib || BSL‑1.0
| unconstrained/box-constrained nonlinear/QP optimization library written in C++.
|-
| GEKKO || MIT
| machine learning and optimization of mixed-integer and differential algebraic equations in Python.
|-
| GLPK || GPL
| GNU Linear Programming Kit with C API.
|-
| HiGHS || MIT
| linear programming (LP), mixed integer programming (MIP), and convex quadratic programming (QP).
|-
| IPOPT || EPL (was CPL)
| large scale nonlinear optimizer for continuous systems (requires gradient), C++ (formerly Fortran and C). It became a part of COIN-OR.
|-
| MINUIT (now MINUIT2) || LGPL
| unconstrained optimizer internally developed at CERN.
|-
| OpenMDAO || Apache License
| Multidisciplinary Design, Analysis, and Optimization (MDAO) framework, written in Python. The development is led out of the NASA Glenn Research Center, with support from the NASA Langley Research Center.
|-
| SCIP || Apache License
| solver for mixed integer programming (MIP) and mixed integer nonlinear programming (MINLP).
|-
| SciPy || BSD
| general numeric package for Python, with some support for optimization.
|-
| Uno || MIT
| Lagrange-Newton solver that unifies nonconvex optimization, implemented in C++. Developed at Argonne National Laboratory and Zuse Institute Berlin.
|}
Proprietary software
AIMMS – optimization modelling system, including GUI building facilities.
ALGLIB – dual licensed (GPL/commercial) constrained quadratic and nonlinear optimization library with C++ and C# interfaces.
Altair HyperStudy – design of experiments and multidisciplinary design optimization.
AMPL – modelling language for large-scale linear, mixed integer and nonlinear optimization.
ANTIGONE – a deterministic global optimization MINLP solver.
APMonitor – modelling language and optimization suite for large-scale, nonlinear, mixed integer, differential, and algebraic equations with interfaces to MATLAB, Python, and Julia.
Artelys Knitro – large scale nonlinear optimization for continuous and mixed-integer programming.
ASTOS – AeroSpace Trajectory optimization Software for launch, re-entry, and generic aerospace problems.
BARON – optimization of algebraic nonlinear and mixed-integer nonlinear problems.
COMSOL Multiphysics – a cross-platform finite element analysis, solver and multiphysics simulation software.
CPLEX – solver for linear and quadratic programming with continuous or integer variables (MIP).
FEATool Multiphysics – FEA GUI Toolbox for MATLAB.
FICO Xpress – solver for linear and quadratic programming with continuous or integer variables (MIP).
FortMP – linear and quadratic programming.
FortSP – stochastic programming.
GAMS – General Algebraic Modeling System.
Gurobi Optimizer – solver for linear and quadratic programming with continuous or integer variables (MIP).
HEEDS MDO – multidisciplinary design optimization using SHERPA, a hybrid, adaptive optimization algorithm.
IMSL Numerical Libraries – linear, quadratic, nonlinear, and sparse QP and LP optimization algorithms implemented in standard programming languages C, Java, C# .NET, Fortran, and Python.
IOSO – (Indirect optimization on the basis of Self-Organization) a multi-objective, multidimensional nonlinear optimization technology.
Kimeme – an open platform for multi-objective optimization and multidisciplinary design optimization.
LINDO (Linear, Interactive, and Discrete optimizer) a software package for linear programming, integer programming, nonlinear programming, stochastic programming, and global optimization. The "What's Best!" Excel add-in performs linear, integer, and nonlinear optimization using LINDO.
LIONsolver – an integrated software for data mining, analytics, modelling Learning and Intelligent OptimizatioN and reactive business intelligence approach.
modeFRONTIER – an integration platform for multi-objective and multidisciplinary optimization, which provides a seamless coupling with third party engineering tools, enables the automation of the design simulation process, and facilitates analytic decision-making.
Maple – linear, quadratic, and nonlinear, continuous and integer optimization. Constrained and unconstrained. Global optimization with add-on toolbox.
MATLAB – linear, integer, quadratic, and nonlinear problems with Optimization Toolbox; multiple maxima, multiple minima, and non-smooth optimization problems; estimation and optimization of model parameters.
MIDACO a lightweight software tool for single- and multi-objective optimization based on evolutionary computing. Written in C/C++ and Fortran with gateways to Excel, VBA, Java, Python, Matlab, Octave, R, C#, and Julia.
Mathematica – large-scale multivariate constrained and unconstrained, linear, quadratic and nonlinear, continuous, and integer optimization.
ModelCenter – a graphical environment for integration, automation, and design optimization.
MOSEK – linear, quadratic, conic and convex nonlinear, continuous, and integer optimization.
NAG – linear, quadratic, nonlinear, sums of squares of linear or nonlinear functions; linear, sparse linear, nonlinear, bounded or no constraints; local and global optimizations; continuous or integer problems.
NMath – linear, quadratic and nonlinear programming.
Octeract Engine – a deterministic global optimization MINLP solver. Plans exist for additional features.
OptimJ – Java-based modelling language. Premium Edition includes support for Mosek and CPLEX solvers.
Optimus platform – a process integration and design optimization platform developed by Noesis Solutions.
optiSLang – software solutions for CAE-based sensitivity analysis, optimization, and robustness evaluation.
OptiY a design environment providing modern optimization strategies and state of the art probabilistic algorithms for uncertainty, reliability, robustness, sensitivity analysis, data-mining, and meta modelling.
OptiStruct – award-winning CAE technology for conceptual design synthesis and structural optimization.
OptQuest – metaheuristics-based optimization plugin for simulation-based optimization in conjunction with discrete-event simulation software.
PottersWheel – parameter estimation in ordinary differential equations (MATLAB toolbox, free for academic use).
pSeven software platform for automation of engineering simulation and analysis, multidisciplinary optimization and data mining, developed by DATADVANCE.
SAS – a software suite developed by SAS Institute for advanced analytics (statistics, forecasting, machine learning, optimization, etc.), business intelligence, customer intelligence, data management, risk management, and many more.
SmartDO – multidisciplinary global design optimization, specialized in computer-aided engineering (CAE). using the direct global search approaches.
SNOPT – large-scale optimization problems.
The Unscrambler – product formulation and process optimization software.
TOMLAB – supports global optimization, integer programming, all types of least squares, linear, quadratic, and unconstrained programming for MATLAB. TOMLAB supports solvers like CPLEX, SNOPT, KNITRO and MIDACO.
VisSim – a visual block diagram language for simulation and optimization of dynamical systems.
WORHP – a large-scale sparse solver for continuous nonlinear optimization.
Freeware/free for academic use
AIMMS
AMPL
APMonitor – free for academic and commercial use alike, with Python and MATLAB integrations.
ASTOS
CPLEX
Couenne – An open source solver for the deterministic global optimization of MINLPs licensed under the Eclipse Public License.
FICO Xpress
Galahad library
Gekko
Gurobi Optimizer - free for academic users
LIONsolver
MIDACO – a software package for numerical optimization based on evolutionary computing.
MINTO – integer programming solver using branch and bound algorithm; freeware for personal use.
MOSEK – a large scale optimization software. Solves linear, quadratic, conic and convex nonlinear, continuous and integer optimization.
OptimJ – Java-based modelling language; the free edition includes support for lp_solve, GLPK and LP or MPS file formats.
PottersWheel – parameter estimation in ordinary differential equations (free MATLAB toolbox for academic use).
Pyomo collection of Python software packages for formulating optimization models.
UFO Fortran package for numerical optimization
WORHP
See also
Comparison of optimization software
List of computer algebra systems
List of constraint programming languages
List of numerical libraries
List of optimization algorithms
List of SMT solvers
References
Optimization software | List of optimization software | [
"Technology"
] | 2,401 | [
"Computing-related lists",
"Lists of software"
] |
12,013,342 | https://en.wikipedia.org/wiki/Chemical%20transport%20reaction | In chemistry, a chemical transport reaction describes a process for purification and crystallization of non-volatile solids. The process is also responsible for certain aspects of mineral growth from the effluent of volcanoes. The technique is distinct from chemical vapor deposition, which usually entails decomposition of molecular precursors and which gives conformal coatings.
The technique, which was popularized by Harald Schäfer, entails the reversible conversion of nonvolatile elements and chemical compounds into volatile derivatives. The volatile derivative migrates throughout a sealed reactor, typically a sealed and evacuated glass tube heated in a tube furnace. Because the tube is under a temperature gradient, the volatile derivative reverts to the parent solid and the transport agent is released at the end opposite to which it originated (see next section). The transport agent is thus catalytic. The technique requires that the two ends of the tube (which contains the sample to be crystallized) be maintained at different temperatures. So-called two-zone tube furnaces are employed for this purpose. The method derives from the Van Arkel de Boer process which was used for the purification of titanium and vanadium and uses iodine as the transport agent.
Cases of the exothermic and endothermic reactions of the transporting agent
Transport reactions are classified according to the thermodynamics of the reaction between the solid and the transporting agent. When the reaction is exothermic, then the solid of interest is transported from the cooler end (which can be quite hot) of the reactor to a hot end, where the equilibrium constant is less favorable and the crystals grow. The reaction of molybdenum dioxide with the transporting agent iodine is an exothermic process, thus the MoO2 migrates from the cooler end (700 °C) to the hotter end (900 °C):
MoO2 + I2 MoO2I2 ΔHrxn < 0 (exothermic)
Using 10 milligrams of iodine for 4 grams of the solid, the process requires several days.
Alternatively, when the reaction of the solid and the transport agent is endothermic, the solid is transported from a hot zone to a cooler one. For example:
Fe2O3 + 6 HCl Fe2Cl6+ 3 H2O ΔHrxn > 0 (endothermic)
The sample of iron(III) oxide is maintained at 1000 °C, and the product is grown at 750 °C. HCl is the transport agent. Crystals of hematite are reportedly observed at the mouths of volcanoes because of chemical transport reactions whereby volcanic hydrogen chloride volatilizes iron(III) oxides.
Halogen lamp
A similar reaction like that of MoO2 is used in halogen lamps. The tungsten is evaporated from the tungsten filament and converted with traces of oxygen and iodine into the WO2I2, at the high temperatures near the filament the compound decomposes back to tungsten, oxygen and iodine.
WO2 + I2 WO2I2, ΔHrxn < 0 (exothermic)
References
Inorganic chemistry
Solid-state chemistry | Chemical transport reaction | [
"Physics",
"Chemistry",
"Materials_science"
] | 650 | [
"Condensed matter physics",
"nan",
"Solid-state chemistry"
] |
12,015,290 | https://en.wikipedia.org/wiki/Doubly%20connected%20edge%20list | The doubly connected edge list (DCEL), also known as half-edge data structure, is a data structure to represent an embedding of a planar graph in the plane, and polytopes in 3D. This data structure provides efficient manipulation of the topological information associated with the objects in question (vertices, edges, faces). It is used in many algorithms of computational geometry to handle polygonal subdivisions of the plane, commonly called planar straight-line graphs (PSLG). For example, a Voronoi diagram is commonly represented by a DCEL inside a bounding box.
This data structure was originally suggested by Muller and Preparata for representations of 3D convex polyhedra. Simplified versions of the data structure, as described here, only consider connected graphs, but the DCEL structure may be extended to handle disconnected graphs as well by introducing dummy edges between disconnected components.
Data structure
DCEL is more than just a doubly linked list of edges. In the general case, a DCEL contains a record for each edge, vertex and face of the subdivision. Each record may contain additional information, for example, a face may contain the name of the area. Each edge usually bounds two faces and it is, therefore, convenient to regard each edge as two "half-edges" (which are represented by the two edges with opposite directions, between two vertices, in the picture on the right). Each half-edge is "associated" with a single face and thus has a pointer to that face. All half-edges associated with a face are clockwise or counter-clockwise. For example, in the picture on the right, all half-edges associated with the middle face (i.e. the "internal" half-edges) are counter-clockwise. A half-edge has a pointer to the next half-edge and previous half-edge of the same face. To reach the other face, we can go to the twin of the half-edge and then traverse the other face. Each half-edge also has a pointer to its origin vertex (the destination vertex can be obtained by querying the origin of its twin, or of the next half-edge).
Each vertex contains the coordinates of the vertex and also stores a pointer to an arbitrary edge that has the vertex as its origin. Each face stores a pointer to some half-edge of its outer boundary (if the face is unbounded then pointer is null). It also has a list of half-edges, one for each hole that may be incident within the face. If the vertices or faces do not hold any interesting information, there is no need to store them, thus saving space and reducing the data structure's complexity.
See also
Quad-edge data structure
Doubly linked face list
Winged edge
Combinatorial map
References
Graph data structures
Geometric graph theory
Geometric data structures | Doubly connected edge list | [
"Mathematics"
] | 585 | [
"Geometric graph theory",
"Mathematical relations",
"Graph theory"
] |
12,015,467 | https://en.wikipedia.org/wiki/Kaya%20identity | The Kaya identity is a mathematical identity stating that the total emission level of the greenhouse gas carbon dioxide can be expressed as the product of four factors: human population, GDP per capita, energy intensity (per unit of GDP), and carbon intensity (emissions per unit of energy consumed). It is a concrete form of the more general I = PAT equation relating factors that determine the level of human impact on climate. Although the terms in the Kaya identity would in theory cancel out, it is useful in practice to calculate emissions in terms of more readily available data, namely population, GDP per capita, energy per unit GDP, and emissions per unit energy. It furthermore highlights the elements of the global economy on which one could act to reduce emissions, notably the energy intensity per unit GDP and the emissions per unit energy.
Overview
The Kaya identity was developed by Japanese energy economist Yoichi Kaya. It is the subject of his book Environment, Energy, and Economy: strategies for sustainability co-authored with Keiichi Yokobori as the output of the Conference on Global Environment, Energy, and Economic Development (1993 : Tokyo, Japan). It is a variation of Paul R. Ehrlich & John Holdren's I=PAT formula that describes the factors of environmental impact.Kaya identity is expressed in the form:
Where:
F is global emissions from human sources
P is global population
G is world GDP
E is global energy consumption
And:
G/P is the GDP per capita
E/G is the energy intensity of the GDP
F/E is the emission intensity of energy
Use in IPCC reports
The Kaya identity plays a core role in the development of future emissions scenarios in the IPCC Special Report on Emissions Scenarios. The scenarios set out a range of assumed conditions for future development of each of the four inputs. Population growth projections are available independently from demographic research; GDP per capita trends are available from economic statistics and econometrics; similarly for energy intensity and emission levels. The projected carbon emissions can drive carbon cycle and climate models to predict future CO2 concentration and global warming.
Other uses
Bill Gates used a form of the Identity, without attribution, at a TED Talk called "Innovating to zero!". Writing in ThinkProgress'', Joseph J. Romm disputed the validity of Gates' arguments, as well as clarifying the key idea behind the identity.
See also
Eco-economic decoupling
Eco-efficiency
Eco-sufficiency
Global carbon reward
Industrial ecology
I = PAT
Life cycle analysis
Transport ecology
References
External links
Systems thinking
Environmental economics
Prediction
Climate change | Kaya identity | [
"Environmental_science"
] | 525 | [
"Environmental economics",
"Environmental social science"
] |
12,015,517 | https://en.wikipedia.org/wiki/Planar%20straight-line%20graph | In computational geometry and geometric graph theory, a planar straight-line graph (or straight-line plane graph, or plane straight-line graph), in short PSLG, is an embedding of a planar graph in the plane such that its edges are mapped into straight-line segments. Fáry's theorem (1948) states that every planar graph has this kind of embedding.
In computational geometry, PSLGs have often been called planar subdivisions, with an assumption or assertion that subdivisions are polygonal rather than having curved boundaries.
PSLGs may serve as representations of various maps, e.g., geographical maps in geographical information systems.
Special cases of PSLGs are triangulations (polygon triangulation, point-set triangulation). Point-set triangulations are maximal PSLGs in the sense that it is impossible to add straight edges to them while keeping the graph planar. Triangulations have numerous applications in various areas.
PSLGs may be seen as a special kind of Euclidean graphs. However, in discussions involving Euclidean graphs, the primary interest is their metric properties, i.e., distances between vertices, while for PSLGs the primary interest is the topological properties. For some graphs, such as Delaunay triangulations, both metric and topological properties are of importance.
Representations
There exist three well-known data structures for representing PSLGs, these are the Winged-edge data structure, Halfedge, and Quadedge. The winged-edge data structure is the oldest of the three, but manipulating it often requires complicated case distinctions. This is because edge references do not store the edge direction, and the directions of edges around a face need not be consistent. The halfedge data structure stores both orientations of an edge and links them properly, simplifying operations and the storage scheme. The Quadedge data structure stores both the planar subdivision and its dual simultaneously. Its records consist explicitly only of edge records, four for each edge, and in a simplified form it is suitable for storing PSLGs.
Problems in terms of PSLG
Point location. For a query point, find which face of the PSLG it belongs to.
Map overlay. Find the overlay of two PSLGs (maps), which is the subdivision of the plane by the two simultaneously embedded PSLGs. In GIS this problem is known as "thematic map overlay".
See also
Doubly connected edge list, a data structure to represent a PSLG
Local feature size
References
Geometric algorithms
Geometric graphs
Planar graphs | Planar straight-line graph | [
"Mathematics"
] | 536 | [
"Planes (geometry)",
"Planar graphs"
] |
12,017,057 | https://en.wikipedia.org/wiki/Self-focusing | Self-focusing is a non-linear optical process induced by the change in refractive index of materials exposed to intense electromagnetic radiation. A medium whose refractive index increases with the electric field intensity acts as a focusing lens for an electromagnetic wave characterized by an initial transverse intensity gradient, as in a laser beam. The peak intensity of the self-focused region keeps increasing as the wave travels through the medium, until defocusing effects or medium damage interrupt this process. Self-focusing of light was discovered by Gurgen Askaryan.
Self-focusing is often observed when radiation generated by femtosecond lasers propagates through many solids, liquids and gases. Depending on the type of material and on the intensity of the radiation, several mechanisms produce variations in the refractive index which result in self-focusing: the main cases are Kerr-induced self-focusing and plasma self-focusing.
Kerr-induced self-focusing
Kerr-induced self-focusing was first predicted in the 1960s and experimentally verified by studying the interaction of ruby lasers with glasses and liquids. Its origin lies in the optical Kerr effect, a non-linear process which arises in media exposed to intense electromagnetic radiation, and which produces a variation of the refractive index as described by the formula , where n0 and n2 are the linear and non-linear components of the refractive index, and I is the intensity of the radiation. Since n2 is positive in most materials, the refractive index becomes larger in the areas where the intensity is higher, usually at the centre of a beam, creating a focusing density profile which potentially leads to the collapse of a beam on itself. Self-focusing beams have been found to naturally evolve into a Townes profile regardless of their initial shape.
Self-focusing beyond a threshold of power can lead to laser collapse and damage to the medium, which occurs if the radiation power is greater than the critical power
,
where λ is the radiation wavelength in vacuum and α is a constant which depends on the initial spatial distribution of the beam. Although there is no general analytical expression for α, its value has been derived numerically for many beam profiles. The lower limit is α ≈ 1.86225, which corresponds to Townes beams, whereas for a Gaussian beam α ≈ 1.8962.
For air, n0 ≈ 1, n2 ≈ 4×10−23 m2/W for λ = 800 nm, and the critical power is Pcr ≈ 2.4 GW, corresponding to an energy of about 0.3 mJ for a pulse duration of 100 fs. For silica, n0 ≈ 1.453, n2 ≈ 2.4×10−20 m2/W,
and the critical power is Pcr ≈ 2.8 MW.
Kerr-induced self-focusing is crucial for many applications in laser physics, both as a key ingredient and as a limiting factor. For example, the technique of chirped pulse amplification was developed to overcome the nonlinearities and damage of optical components that self-focusing would produce in the amplification of femtosecond laser pulses. On the other hand, self-focusing is a major mechanism behind Kerr-lens modelocking, laser filamentation in transparent media, self-compression of ultrashort laser pulses, parametric generation, and many areas of laser-matter interaction in general.
Self-focusing and defocusing in gain medium
Kelley predicted that homogeneously broadened two-level atoms may focus or defocus light when carrier frequency is detuned downward or upward the center of gain line . Laser pulse propagation with slowly varying envelope is governed in gain medium by the nonlinear Schrödinger-Frantz-Nodvik equation.
When is detuned downward or upward from the refractive index is changed. "Red" detuning leads to an increased index of refraction during saturation of the resonant transition, i.e. to self-focusing, while for "blue" detuning the radiation is defocused during saturation:
where is the stimulated emission cross section, is the population inversion density before pulse arrival, and are longitudinal and transverse lifetimes of two-level medium and is the propagation axis.
Filamentation
The laser beam with a smooth spatial profile is affected by modulational instability. The small perturbations caused by roughnesses and medium defects are amplified in propagation. This effect is referred to as Bespalov-Talanov instability.
In a framework of nonlinear Schrödinger equation :
.
The rate of the perturbation growth or instability increment
is linked with filament size via simple equation:
. Generalization of this link between Bespalov-Talanov increments and filament size in gain medium as a function of linear gain and detuning
had been realized in
.
Plasma self-focusing
Advances in laser technology have recently enabled the observation of self-focusing in the interaction of intense laser pulses with plasmas. Self-focusing in plasma can occur through thermal, relativistic and ponderomotive effects. Thermal self-focusing is due to collisional heating of a plasma exposed to electromagnetic radiation: the rise in temperature induces a hydrodynamic expansion which leads to an increase of the index of refraction and further heating.
Relativistic self-focusing is caused by the mass increase of electrons travelling at speed approaching the speed of light, which modifies the plasma refractive index nrel according to the equation
,
where ω is the radiation angular frequency and ωp the relativistically corrected plasma frequency .
Ponderomotive self-focusing is caused by the ponderomotive force, which pushes electrons away from the region where the laser beam is more intense, therefore increasing the refractive index and inducing a focusing effect.
The evaluation of the contribution and interplay of these processes is a complex task, but a reference threshold for plasma self-focusing is the relativistic critical power
,
where me is the electron mass, c the speed of light, ω the radiation angular frequency, e the electron charge and ωp the plasma frequency. For an electron density of 1019 cm−3 and radiation at the wavelength of 800 nm, the critical power is about 3 TW. Such values are realisable with modern lasers, which can exceed PW powers. For example, a laser delivering 50 fs pulses with an energy of 1 J has a peak power of 20 TW.
Self-focusing in a plasma can balance the natural diffraction and channel a laser beam. Such effect is beneficial for many applications, since it helps increasing the length of the interaction between laser and medium. This is crucial, for example, in laser-driven particle acceleration, laser-fusion schemes and high harmonic generation.
Accumulated self-focusing
Self-focusing can be induced by a permanent refractive index change resulting from a multi-pulse exposure. This effect has been observed in glasses which increase the refractive index during an exposure to ultraviolet laser radiation. Accumulated self-focusing develops as a wave guiding, rather than a lensing effect. The scale of actively forming beam filaments is a function of the exposure dose. Evolution of each beam filament towards a singularity is limited by the maximum induced refractive index change or by laser damage resistance of the glass.
Self-focusing in soft matter and polymer systems
Self-focusing can also been observed in a number of soft matter systems, such as solutions of polymers and particles as well as photo-polymers. Self-focusing was observed in photo-polymer systems with microscale laser beams of either UV or visible light. The self-trapping of incoherent light was also later observed. Self-focusing can also be observed in wide-area beams, wherein the beam undergoes filamentation, or Modulation Instability, spontaneous dividing into a multitude of microscale self-focused beams, or filaments. The balance of self-focusing and natural beam divergence results in the beams propagating divergence-free. Self-focusing in photopolymerizable media is possible, owing to a photoreaction dependent refractive index, and the fact that refractive index in polymers is proportional to molecular weight and crosslinking degree which increases over the duration of photo-polymerization.
See also
Filament propagation
References
Bibliography
Nonlinear optics
Plasma phenomena
Laser science | Self-focusing | [
"Physics"
] | 1,701 | [
"Plasma phenomena",
"Physical phenomena",
"Plasma physics"
] |
12,017,661 | https://en.wikipedia.org/wiki/Antibiosis | Antibiosis, also referred to as antagonism, a process of biological interaction between two or more organisms that is detrimental to at least one of them; it can also be an antagonistic association between an organism and the metabolic substances produced by another. Antibiosis can occur through a variety of mechanisms, with "injury, death, reduced longevity, or reduced reproduction of the pest" being common. The process of antibiosis is either reversible or irreversible, and is caused by the production of volatile organic compounds by plant-growth-promoting rhizobacterium (PGPR). Antibiosis is one of two forms of amensalism, the other form being competition. Primary examples of antibiosis include "antibacterial activity against bacteria, fungus, nematodes, insects, and occasionally against plants and algae".
Examples of Antibiosis
Antibiosis in biotech and medical treatment
The study of antibiosis and its role in antibiotics has led to the expansion of knowledge in the field of microbiology. Molecular processes such cell wall synthesis and recycling, for example, have become better understood through the study of how antibiotics affect beta-lactam development through the antibiosis relationship and interaction of the particular drugs with the bacteria subjected to the compound. For example, the Penicillium fungi responds to bacterial infections by producing penicillin, which is toxic to bacteria and is commonly used in medical settings as an effective treatment for bacterial infections. Penicillin belongs to the beta-lactam antibiotic class.
Host plant resistance through antibiosis
Antibiosis is typically studied in host plant populations and extends to the insects which feed upon them. Antibiosis can be seen in certain vegetables, as antibiosis mechanisms have been found in Brassica species to protect against cabbage whitefly.
"Antibiosis resistance affects the biology of the insect so pest abundance and subsequent damage is reduced compared to that which would have occurred if the insect was on a susceptible crop variety. Antibiosis resistance often results in increased mortality or reduced longevity and reproduction of the insect."
During a study of antibiosis, it was determined that the key to achieving effective antibiosis relies on the organism being sessile. "When you give antibiotic-producing bacteria a structured medium, they affix to substrate, grow clonally, and produce a 'no man's land,' absent competitors, where the antibiotics diffuse outward." Antibiosis is most effective when resources are neither plentiful nor sparse. Antibiosis should be considered as the median on the scale of resource, due to its ideal performance.
Other examples
The black walnut, Juglans nigra, produces a secretion called juglone, which is toxic to a variety of flowers, herbaceous plants, and field crops. This toxic secretion creates an area surrounding the black walnut tree that is uninhabitable to most species.
In many environments, antibiosis can promote mutualisms and/or competition between species in an ecosystem. Attine ants provide an example of a more complex antibiosis mechanism. Attine ants maintain cultivations of Leucocoprinus fungi as their primary source of consumption, however, a parasitic fungal genus, Escovopsis, feeds on Leucocoprinus and disrupts the food system of the ants. In response to this, attine ants encourage growth of the Pseudonocardia actinomycete, as it produces an antimicrobial compound that suppresses the parasitic Escovopsis. The attine ants, Leucocoprinus fungi and Pseudonocardia actinomycete all benefit in this interaction, however it is detrimental to the Escovopsis fungi.
See also
Antibiotic
Biological pest control
Biotechnology
Symbiosis
Plant defense against herbivory
Secondary metabolite
Competition (biology)
References
Further reading
External links
Biological interactions
Antibiotics
pt:Relação ecológica#Amensalismo ou antibiose | Antibiosis | [
"Biology"
] | 818 | [
"Behavior",
"Biotechnology products",
"Biological interactions",
"Antibiotics",
"nan",
"Ethology",
"Biocides"
] |
12,019,156 | https://en.wikipedia.org/wiki/Aeromechanics | Aeromechanics is the science about mechanics that deals with the motion of air and other gases, involving aerodynamics, thermophysics and aerostatics. It is the branch of mechanics that deals with the motion of gases (especially air) and their effects on bodies in the flow. The fluid flow and structure are interactive systems and their interaction is dynamic. The fluid force causes the structure to deform which changes its orientation to the flow and hence the resulting fluid force.
Areas that comprise this are within the technology of aircraft and helicopters since these use propellers and rotors. Additionally, aeromechanics is critical in the design and analysis of wind turbines, drones, and various unmanned aerial vehicles (UAVs). The principles of aeromechanics are also applied in space exploration vehicles, where the behavior of gases in different atmospheric conditions is crucial. Understanding these interactions is essential for optimizing performance, ensuring stability and control, and improving the efficiency and safety of flight and other applications involving fluid-structure interactions.
See also
Aerodynamics
Aerodynamics | Aeromechanics | [
"Chemistry",
"Engineering"
] | 216 | [
"Aerospace engineering",
"Aerodynamics",
"Fluid dynamics stubs",
"Fluid dynamics"
] |
12,019,625 | https://en.wikipedia.org/wiki/J.%20H.%20van%20Lint | Jacobus Hendricus ("Jack") van Lint (1 September 1932 – 28 September 2004) was a Dutch mathematician, professor at the Eindhoven University of Technology, of which he was rector magnificus from 1991 till 1996.
He gained his Ph.D. from Utrecht University in 1957 under the supervision of Fred van der Blij. He was professor of mathematics at Eindhoven University of Technology from 1959 to 1997.
He was appointed a full professor at Eindhoven University of Technology at the age of 26 years. His field of research was initially number theory, but he worked mainly in combinatorics and coding theory.
Van Lint was honored with a great number of awards. He became a member of Royal Netherlands Academy of Arts and Sciences in 1972, received four honorary doctorates, was an honorary member of the Royal Netherlands Mathematics Society (Koninklijk Wiskundig Genootschap), and received a Knighthood.
Books
Coding Theory, 1971.
Combinatorial Theory Seminar Eindhoven University of Technology, 1974
Introduction to Coding Theory, Springer, Graduate Texts in Mathematics, 1982, 3rd. edition 1999.
with Peter Cameron: Designs, Graphs, Codes and their Links, London Mathematical Society Lecture Notes, Cambridge University Press, 1980.
with Richard M. Wilson: A Course in Combinatorics, Cambridge University Press, 1992.
with Gerard van der Geer: Introduction to Coding theory and Algebraic Geometry, Birkhäuser, 1988.
See also
Seidel adjacency matrix
Seidel switching
References
External links
Personal web site
1932 births
2004 deaths
20th-century Dutch mathematicians
Combinatorialists
Academic staff of the Eindhoven University of Technology
Members of the Royal Netherlands Academy of Arts and Sciences
Rectores Magnifici of the Eindhoven University of Technology
People from Bandung | J. H. van Lint | [
"Mathematics"
] | 374 | [
"Combinatorialists",
"Combinatorics"
] |
12,019,736 | https://en.wikipedia.org/wiki/List%20of%20Skype%20features | Skype offers a number of features based around calling (both free and paid), messaging (including instant, voice and text messaging (SMS)), video chat, and file and screen sharing. The following is a partial list of Skype's features:
Instant messaging and chat history
Skype allows users to send instant messages to other users in their contact list. Messages sent to offline users are stored on Skype servers and will be delivered to their recipients as soon as they come online on Skype. Chat history along with the message status will be synchronized across all user devices supported by Skype whenever the user signs in with the same Skype account.
Although Skype allows sending SMS messages, it is not possible to receive SMS messages on Skype so users need a different way to receive responses to the messages they send using Skype. This has been a cause of angst among user who purchase Skype as an alternative to a mobile phone because Microsoft will not refund any purchases even for users who discover this missing feature only after purchasing multi-year contracts. Other than in user complaints on the Microsoft Skype forums, there is no mention on Microsoft or Skype websites that when they say "Send SMS messages," that is just what they mean: users can send but they cannot receive SMS messages.
Chat history
Skype keeps user instant messaging history on user's local computer, and on Skype's cloud for 30 days. Users cannot control how long their chat histories are stored on Skype's servers but can configure that option individually for every their device. Once user signs into Skype on a new device the conversation history is synced with Skype's cloud and stored locally. Skype allows users to remove or edit individual messages during one hour after sending; this affects messages already received by chat interlocutors as well as not delivered to them yet. Skype allows users to delete all saved conversation histories for the device.
Emoticons and formatting
Users can send about 254 emoticons that are displayed either statically or animated, depending on user's settings. There are also hidden emoticons, 241 flags and 63 other. On special occasions, Skype introduces featured emoticons that are later either left as standard (anger), left as hidden (mooning) or removed (captain). Sending an empty message is not possible. Automatic conversion of text into emoticons cannot be disabled.
Formatting text is possible: *text* creates bold text, _text_ creates italic text, {code} text {code} applies monospace font and ~text~ creates strikethrough text. Writing @@ at the beginning of a message will disable any formatting in the message. Placing two exclamation points and a space (!! ) at the beginning of a message will send the entire message in monospace font. A more convenient way to disable formatting for small pieces of text, is to use ```text``` instead of {code}text{code}. Turning off formatting permanently can be achieved with the command /wikimarkup off.
Quoting
Users are able to quote other messages by copying them and pasting them into a new message. A quote shows the message, the original sender, and the timestamp of the original message. The feature is seen as controversial and often useless because people have found ways to create custom quotes.
Calls between Skype and landline / mobile phone numbers
Skype users can call landline and mobile phone numbers (previously known as SkypeOut) using Skype Credit or a calling subscription. Additionally, users can purchase a Skype Number (previously called SkypeIn and Online Number) that lets contacts call their Skype client from a landline or mobile phone.
Outgoing calls
The ability to call landline or mobile phones from Skype was originally branded as SkypeOut, but this term has been dropped in favor of Calls to mobiles and landlines. Skype users can call phone numbers, including landline and mobile phones, for a fee using prepaid Skype Credit or a subscription (see below). This fee can be as low as per minute for most developed countries, and as high as per minute for calls to the Inmarsat numbers.
In January 2007, Skype introduced a 0.03 connection fee for each call that connected to a landline or mobile number.
After 180 days of inactivity, a user's Skype Credit balance is deactivated; however, it can be reactivated.
Subscription calling plans
On 19 December 2006, Skype announced that there would be a new pricing structure in 2007. Details of a new scheme were released 18 January 2007. The initial press release was vague about the new scheme, but it did reveal that there may be a new connection fee.
In January 2007, Skype launched Skype Pro, a prepaid unlimited call subscription for calls that were made inside North America. Skype's unlimited calling offers unlimited calls to anyone, on any phone, within the U.S. and Canada, for a one-time (e.g. annual) fee. As of April 21, 2008, Skype Pro was replaced by new calling subscription plans, which don't require the calls to start from a certain country.
Skype offers several monthly plans that it calls unlimited. However, Skype limits these subscriptions to 10,000 minutes per month, 6 hours per day, and 50 telephone numbers per day. If one of these limits is exceeded, any additional calls are billed at regular rates and connection fees if the user has Skype Credit.
Skype To Go numbers
Users can set up a Skype To Go number which allows them to reach international phones numbers dialled from any landline or mobile. Skype provides a local number (the user chooses the area code) that then connects using Skype Credit to the number in another country. The service also provides the opportunity to dial any number abroad as well.
Toll-free numbers
Calls to most toll-free numbers in Australia (+61 1800), Austria (+43 800), Estonia (+372 800) France (+33 800, +33 801, +33 803, +33 805, +33 806, +33 808, +33 809), Germany (+49 800), the Netherlands (+31 800), Poland (+48 800), Spain (+34 900), Taiwan (+886 801, +886 811), the UK (+44 500, +44 800, +44 808), United Nations (+888) and the United States (+1 800, +1 822, +1 833, +1 844, +1 855, +1 866, +1 877, +1 888) are free for all Skype users.
Support for toll-free numbers in Canada was effectively removed in January 2012.
Emergency numbers
Skype also does not support calling emergency numbers such as 1-1-2 in Europe or 911 in the United States, however they do support this service in Australia, Denmark, Finland, and the United Kingdom.
Caller ID for outgoing calls
Skype offers a feature allowing users to set the caller ID for outgoing calls to telephone numbers. Set-up verification involves sending an SMS text message to a selected mobile phone number, then typing that verification code into a web form. Since most regular home and business telephones cannot receive text messages, this feature is only available to owners of mobile phones.
Incoming calls
Skype Number
Skype Number (formerly called Online Number and until 2010 named SkypeIn) allows a Skype user to receive calls to their Skype client (on whatever device) dialed from mobiles or landlines to a Skype-provided phone number. The number need not be in the same location as the user. For example, a user in San Francisco could create a local telephone number in London. Callers in London could then make a local call to reach that user (who answers on Skype in San Francisco).
Skype offers numbers in Australia, Chile, Denmark, Estonia, Finland, France, Germany, Hong Kong, Hungary, Ireland, Italy, Republic of Korea, Malta, Mexico, Netherlands, New Zealand, Poland, Romania, South Africa, Sweden, Switzerland, the United Kingdom, and the United States.
In Russia some companies, including SIP operators, provide direct numbers, redirecting calls to Skype.
Skype Premium
Skype Premium originally bundled together a number of Skype's features including the selection of a calling subscription, the ability to make group video calls and the ability to screen share with up to 10 other people (person-to-person video calls are free), improved customer support and the removal of ads from the Skype client. However, the Premium product was removed in the summer of 2014 when group video calls and screen sharing were made free.
Voicemail
Skype Voicemail (now called Voice messaging) was released on March 10, 2005. This service allows callers to leave voicemail messages for Skype users who are indisposed. Leaving voicemail messages became a free service in 2012.
Video calling and screen sharing
Skype 2.0 and later, on Microsoft Windows (DirectX 9.0 or above required), Mac OS X, and Linux, supports video calling for Skype-to-Skype calls between two parties. Skype 3.6 and later on Windows and Skype 5.3 and later on Mac supports 720p high-definition video. Skype 5.8 and later on Windows and Skype 5.5 for Mac support 1080p high-definition video with the Logitech C920 webcam as well as the primary use of H.264 video codec instead of VP8 found in past versions. Skype 3.0.0 on iOS allows iPhone, iPad and iPod Touch users to call each other, as well as Windows, Linux and Mac OS X. Skype 5 supports group video calls. Sharing of external monitors is also supported via third party hardware.
In 2019, Skype added an option to blur the background using A.I. algorithms purely done using software, despite a depth sensing camera not being present in most webcams.
SMS text messaging
Like many other instant messaging services, Skype clients can send SMS text messages to mobile phone numbers. In the United States, China, and Taiwan, Skype uses a "generic, pre-defined number" as the sender ID. In other countries, the message can be set to appear coming from a verified mobile number, allowing recipients to reply, or else show the first 11 characters of the Skype username. However, as of March 2015, Skype users cannot receive SMS, despite a continuing series of requests and complaints.
Costs are generally lower than standard SMS charges; for example Skype's UK rate per SMS message including VAT is 6.4p, compared to standard rates of 10p or 12p; for international SMS costs will be significantly cheaper using Skype.
Wireless hotspot network access
Skype WiFi (previously called Skype Access) allows users to pay a per-minute charge for Internet access at commercial wireless hotspots using Skype Credit. As of May 2010, Skype lists more than 100 participating networks. This replaced an earlier feature Skype Zones Beta which provided subscription-based access at wireless hotspots operated by Boingo and The Cloud.
In February 2017, Microsoft announced plans to discontinue its Skype Wi-Fi service globally. The application will be delisted, and the service itself will no longer function after March 31, 2017.
Application features
Skype Click to Call (formerly called the Skype Web Toolbar) recognizes phone and Skype Numbers, and is available for Internet Explorer, Google Chrome, and Mozilla Firefox on Windows. Such numbers on web pages are replaced with an icon that can be clicked to call the number using Skype, or right-clicked to provide further options, such as adding the number to Skype's list of contacts. The feature detects phone numbers automatically, but a web site developer can override the detection algorithm using a Meta element and mark the valid numbers individually.
A log file is created for each contact on a user's contact list. Log files are stored locally, meaning they are not available if a user switches computers. By default, the option to log conversations is disabled, but can be enabled in the tools / privacy panel.
On Windows, Skype can be run directly from a USB flash drive without being installed on the host computer. On Mac OS X, installation on the host computer is not required.
In December 2017, Microsoft added "Skype Interviews", a shared code editing system for those wishing to run job interviews for programming roles.
Discontinued features
Skype chat
Skype supports group text chat with an interface similar to IRC with up to 150 people.
The Macintosh version used to use the same message view style format as Adium, though with a different filename extension. Message view styles made for Adium could be installed for Skype, and they did not even need to be renamed. There were a couple of cosmetic bugs, but ignoring those, Adium styles worked without modification. This feature is not present in the Windows, Linux, and Pocket PC versions of Skype. This feature has been discontinued starting with Skype 2.7.0.49.
Not Available status
Since Skype 4, the "Not Available" status is supported. This status was removed in Skype 5.
Most Skype versions, including version 4, broadcast a status of "Not Available" after a configured idle time, but Skype 4 no longer allows the user to edit this setting. The only way for the user to configure this idle time setting is to edit the IdleTimeForNA setting in the config.xml file. Since this feature was removed in Skype 5, the edit setting no longer exists in the config.xml file.
Skype 5 and above display other users' "Not Available" status as "Away".
SkypeMe! status
Skype let users set their presence indicator to "SkypeMe!" in earlier versions of Skype software. It invited calls from strangers. Setting one's status to SkypeMe! attracts a number of callers who want to practice a foreign language (usually English), in addition to the expected scammers and spammers. This feature has been hidden from being selectable starting with Skype version 4 and removed completely in version 5. Setting your privacy settings to "allow anyone to contact me" essentially does the same thing minus the presence indicator itself.
Skypecasts
Skypecasting was released on May 3, 2006. Skypecasts were live, moderated conversations allowing groups of up to 100 people to converse, moderated by the "host" who was able to control who was able to speak. The "host" would always remain in control, and could invite people into the speaking area. There was the functionality to mute and eject, both speakers and listeners, or add more people to speak from the listener section. Skypecasts did not support chat windows to share text information (such as URL) with participants. The Skypecast feature was removed in 2008.
Skype Prime
Skype Prime was a beta feature in Skype 3.1. It allowed users to call lines that charged a per minute rate usually for advice on a particular topic. The feature has since been discontinued in later versions of the Windows and Mac clients.
SkypeFind / business directory
SkypeFind was a community-generated directory of business reviews in Skype 3.1. The feature was removed Skype for Windows 4.x client. The business directory replaced SkypeFind but has also been discontinued from version 5.x of the Windows client.
Skype directory search
Earlier Skype versions allowed the user to search the Skype directory for random people to talk to. This feature was effectively discontinued since Skype 4.0. In current Skype releases you can only add contacts for which you know one of the following pieces of information: e-mail address, phone number, full name, or Skype name.
See also
Comparison of VoIP software
Skype protocol
Videoconferencing
Voice over IP
References
Skype
Skype
Teleconferencing
Videotelephony | List of Skype features | [
"Technology"
] | 3,379 | [
"Software features"
] |
12,019,770 | https://en.wikipedia.org/wiki/Steering%20damper | The steering damper or steering stabiliser is a damping device designed to inhibit an undesirable, uncontrolled movement or oscillation of a vehicle steering mechanism, a phenomenon known in motorcycling as the death wobble. The stabilizer absorbs unwanted energy in the side to side motion allowing the forks and shocks to work properly. Many things can cause a motorcycle chassis to get upset such as slamming on brakes, rough road, and lastly improper setup. An upset chassis can be a great deal of danger for the rider oftentimes resulting in a crash. A steering stabilizer slows those movements down resulting in the rider feeling more comfortable on the motorcycle.
On motorcycles
Sport bikes have a short wheelbase and an aggressive steering geometry to provide the ability to make very quick changes in direction. This has the harmful side-effect of making the bike less stable, more prone to feedback from uneven road surfaces, and more difficult to control. If the front wheel significantly deviates from the direction of travel when it touches down, it may cause an unwanted wobble. Steering dampers are factory installed on most sport motorcycles as well as contemporary racing bikes to counter these behaviors.
Steering dampers are also mounted to off-road motorcycles such as motocross and off-road bikes. A damper helps keep the bike tracking straight over difficult terrain such as ruts, rocks, and sand, and also smooths out jolts through the handlebars at the end of jumps. They also reduce arm fatigue by reducing the effort to control the handlebars. While they do help with less fatigue they will not completely take it away.
On motorcycles, one end of the damper is mounted to the steering yoke or triple tree, the other to the frame. Three main types are linear, electronic and radial. Linear dampers resemble a telescoping shock absorber and operate in a similar manner. They can be aligned either longitudinally and to one side of the steering, or transversely across the bike. Radial dampers resemble small boxes and operate via a rotating pivot. They are mounted coaxially with the steering axis and are typically located on top of the triple tree (top of fork leg). An electronically variable damper uses a radial damper with hydraulic fluid that flows freely at low speeds, allowing easy turning, while restricting flow at higher speeds when more damping is necessary, as determined by the ECM (Electronic Control Module). A prime example of this is HPSD (Honda Progressive Steering Damper).
For motorcycles with sidecars, especially for motorcycles which have been retrofitted with a sidecar and where the front wheel geometry, or trail, has not been adjusted for use with a sidecar, a steering damper is beneficial. This prevents low speed wobble which may occur in the lower speed range of about . In older motorcycles adjustable friction dampers had been routinely installed. Hydraulically operated steering dampers may be retrofitted. In some jurisdictions, the installation and operation of a steering damper must be inspected by an expert or examiner and must be entered in the vehicle papers.
On bicycles
Steering dampers have been available for bicycles as well. There is also a mechanism by the same name that consists only of a spring connected to the frame and the fork that merely provides a progressive torque to straighten the steering.
Gallery
References
Motorcycle technology
Vehicle technology | Steering damper | [
"Engineering"
] | 687 | [
"Vehicle technology",
"Mechanical engineering by discipline"
] |
12,020,233 | https://en.wikipedia.org/wiki/Chytridiales | Fungi of the order Chytridiales, like other members of its division, may either have a monocentric thallus or a polycentric rhizomycelium. When the ribosomal genes of members classified in this order were first examined using molecular techniques, it was discovered that the order contained some species that were not related. With the culture and characterization of Chytridium olla, the type species of this order, the limits of the Chytridiales were established. The Chytridiales is now monophyletic and species such as Polychytrium aggregatum, Chytriomyces angularis and Cladochytrium replicatum have been transferred to other orders.
Genera incertae sedis
Achlyella
Achlyogeton
Coralliochytrium
Delfinachytrium
Pseudorhizidium
Dermomycoides
Dictyomorpha
Ichthyochytrium
Mucophilus
Myiophagus
Plasmophagus
Rhizidiocystis
Rhizosiphon
Sagittospora
Septolpidium
Sorokinocystis - Sorokinocystis mirabilis
Trematophlyctis
References
Chytridiomycota
Fungus orders
Aquatic fungi | Chytridiales | [
"Biology"
] | 255 | [
"Fungus stubs",
"Fungi"
] |
12,020,830 | https://en.wikipedia.org/wiki/Spizellomycetales | Spizellomycetales is an order of fungi in the Chytridiomycetes. Spizellomycetalean chytrids are essentially ubiquitous zoospore-producing fungi found in soils where they decompose pollen. Recently they have also been found in dung and harsh alpine environments, greatly expanding the range of habitats where one can expect to find these fungi.
Role in the environment
Spizellomycetalean chytrids have beneficial roles in the soil for nutrient recycling and as parasites of organisms that attack plants, such as nematodes and oospores of downy mildews. On the other hand, they also have detrimental roles as parasites of arbuscular mycorrhizae, symbiotic fungi that help plants gain essential nutrients. Culture isolation studies and molecular characterization of these fungi have demonstrated a great deal of undescribed diversity within the Spizellomycetales, even for isolates collected within the same geographic location. Thus, these understudied fungi await greater exploration.
Taxonomy
The order includes the following genera:
Family Caulochytriaceae Subramanian 1974
Genus Caulochytrium Voos & Olive 1968
Family Powellomycetaceae Simmons 2011
Genus Fimicolochytrium Simmons & Longcore 2012
Genus Geranomyces D.R. Simmons 2011
Genus Powellomyces Longcore, D.J.S. Barr & Désauln. 1995
Genus Thoreauomyces Simmons & Longcore 2012
Family Spizellomycetaceae Barr 1980
Genus Brevicalcar Letcher & M.J. Powell 2017
Genus Bulbomyces Letcher & M.J. Powell 2017
Genus Gaertneriomyces D.J.S. Barr 1980
Genus Gallinipes Letcher & M.J. Powell 2017
Genus Kochiomyces D.J.S. Barr 1980
Genus Spizellomyces D.J.S. Barr 1980
Genus Triparticalcar D.J.S. Barr 1980
See also
Rozella
References
External links
Chytrid Fungi Online: by the University of Alabama
Chytridiomycota
Fungus orders | Spizellomycetales | [
"Biology"
] | 441 | [
"Fungus stubs",
"Fungi"
] |
8,864,768 | https://en.wikipedia.org/wiki/Amoeba%20%28mathematics%29 | In complex analysis, a branch of mathematics, an amoeba is a set associated with a polynomial in one or more complex variables. Amoebas have applications in algebraic geometry, especially tropical geometry.
Definition
Consider the function
defined on the set of all n-tuples of non-zero complex numbers with values in the Euclidean space given by the formula
Here, log denotes the natural logarithm. If p(z) is a polynomial in complex variables, its amoeba is defined as the image of the set of zeros of p under Log, so
Amoebas were introduced in 1994 in a book by Gelfand, Kapranov, and Zelevinsky.
Properties
Let be the zero locus of a polynomial
where is finite, and if and . Let be the Newton polyhedron of , i.e.,
Then
Any amoeba is a closed set.
Any connected component of the complement is convex.
The area of an amoeba of a not identically zero polynomial in two complex variables is finite.
A two-dimensional amoeba has a number of "tentacles", which are infinitely long and exponentially narrow towards infinity.
The number of connected components of the complement is not greater than and not less than the number of vertices of .
There is an injection from the set of connected components of complement to . The vertices of are in the image under this injection. A connected component of complement is bounded if and only if its image is in the interior of .
If , then the area of is not greater than .
Ronkin function
A useful tool in studying amoebas is the Ronkin function. For p(z), a polynomial in n complex variables, one defines the Ronkin function
by the formula
where denotes Equivalently, is given by the integral
where
The Ronkin function is convex and affine on each connected component of the complement of the amoeba of .
As an example, the Ronkin function of a monomial
with is
References
.
Further reading
External links
Amoebas of algebraic varieties
Algebraic geometry | Amoeba (mathematics) | [
"Mathematics"
] | 415 | [
"Fields of abstract algebra",
"Algebraic geometry"
] |
8,865,211 | https://en.wikipedia.org/wiki/Tractors%20in%20India | Tractors in India are a major industry and significant contributor to its agriculture output gains.
In 1947, as India gained independence from the British Empire, the level of agriculture mechanisation was low. The socialist oriented five-year plans of the 1950s and 1960s aggressively promoted rural mechanisation via joint ventures and tie-ups between local industrialists and international tractor manufacturers. Despite these efforts, the first three decades after independence local production of 4-wheel tractors grew slowly. By the late 1980s tractor production was nearly 140,000 units per year, and a prevalence rate of less than 2 per 1,000 farmers.
After economic reforms of 1991, the pace of change increased and by late 1990s with production approached 270,000 per year. In early 2000s, India overtook the United States as the world's largest producer of four-wheel tractors. FAO estimated, in 1999, that of total agricultural area in India, less than 50% is under mechanised land preparation, indicating large opportunities still exist for agricultural mechanisation.
In 2013, India produced 619,000 tractors accounting for 29% of world's output, as the world's largest producer and market for tractors. India currently has 16 domestic and 4 multinational corporations manufacturing tractors.
History of tractors in India
1945 to 1960
War surplus tractors and bulldozers were imported for land reclamation and cultivation in mid-1940s. In 1947 central and state tractor organisations were set up to develop and promote the supply and use of tractors in agriculture and up to 1960, the demand was met entirely through imports. There were 8,500 tractors in use in 1951, 20,000 in 1955 and 37,000 by 1960.In this period Massey Ferguson entered India With Massey Ferguson 35x and 135
1960–1970
By 1970 annual production had exceeded 20,000 units with over 146,000 units working in the country.
1971 to 1980
By late 60's the government of India initiated the Green Revolution in India program and the need for mechanisation created more demands for farm tractors.To meet the initial demand the Government allowed lot of imports mostly from USSR and its Eastern Bloc neighbours. In addition six new manufacturers were established during this period although three companies (Kirloskar Tractors, Harsha Tractors and Pittie Tractors) did not survive. HMT, a large public sector unit, began manufacturing Agricultural Tractors in 1972 under the HMT brand name with technology acquired from Zetor of the Czech Republic (and in year 2016 this company was shut down by the government of India). Escorts Ltd. began local manufacture of Ford tractors in 1971 in collaboration with Ford, UK and total production climbed steadily to 33,000 in 1975–76
1981 to 1990
A further five manufacturers(Auto Tractors, Haryana Tractors, United Auto Tractors, Asian Tractors, and VST Tillers) began production during this period but only VST has survived in the increasingly competitive marketplace. Annual production exceeded 75,000 units by 1985 and reached 140,000 in 1990 when the total in use was about 1.2 million. Than India – a net importer up to the mid-seventies – became an exporter in the 1980s mainly to countries in Africa.
1991 to 1997
Since 1992, it has not been necessary to obtain an industrial license for tractor manufacture in India. By 1997 annual production exceeded 255,000 units and the national tractor population had passed the two million mark. India now emerged as one of the world leaders in wheeled tractor production.
1997 to 1999
Five new manufacturers started production in this period. In 1996 Sonalika tractors started its first tractor manufacturing plant in Hosiarpur, then in 1998 Bajaj Tempo, later renamed Force Motors, began tractor production in Pune. In April of the same year New Holland Tractor (India) Ltd launched production of 70 hp tractors with matching equipment by investing $US 75 million in a state-of-the-art plant at Greater Noida in Uttar Pradesh state with an initial capacity of 35000 units per year. Also during this time, Larsen and Toubro established a joint venture with John Deere of the United States, for the manufacture of 35–65 hp tractors at a plant in Pune, Maharashtra. And Greeves Ltd began producing tractors under similar arrangements with Deutz-Fahr of Italy. Captain Tractors has rolled out first indigenous Mini Tractor of 9.5 hp for small and marginal farmers. CASE now Case IH looking to develop a joint venture in India went into discussions with various Indian companies and in 1999 settled with New Holland Pvt Ltd. India for manufacturing CASE brand tractors and harvesting equipment at New Holland's facility.
1999 to present
Facing market saturation in the traditional markets of the north west (Punjab, Haryana, Western Uttar Pradesh) tractors sales began a slow and slight decline. By 2002 sales went below 200,000. Manufacturers expanded into eastern and southern India markets in an attempt to reverse the decline, and began exploring the potential for overseas markets.
In 2013, India produced 619,000 tractors accounting for 29% of world's output. It is the world's largest producer and market for tractors. India currently has 16 domestic and 4 multinational corporations manufacturing tractors. In 2014 Zetor come back in India and linked with the local tractor manufacture companies to supply 40 to 75 hp tractors on zetor brand name to other countries.
Characteristics, prevalence and market share
Market Characteristics:
Despite the growing availability and sales in the higher HP utility tractors in the category 2 (50 -100 HP) and even in category 3 (100–180 HP) the average HP remains between 40 and 45 HP.
While the industry remains very competitive nationally and internationally and with ever increasing numbers of OEMs, the manufactures are offering quality improvements in engine efficiency and emissions, better selection in transmissions, power steering, etc., they have also managed to keep prices down by limiting offerings in digitalization (little or no use of engine control modules- ECM) of the engine-tractor, roll over protection systems as optional, and the other bells and whistles for operators that come as standard options elsewhere.
Very competitive and widely available repair services due in part to keeping things simple (no ECMs, etc.).
Sales are also driven as the "agricultural" tractors are widely used in providing commercial transport services in rural and peri-urban areas. The cost of a tractor and trailer are much less than the higher speed commercial truck offerings in the 1 – 5 ton sector.
Prevalence:
Tractors are getting widespread acceptance in India.
Kotaks and ICRA reports estimate that nearly 4.3 million tractors were in operation, and 1 in 20 rural households owned a tractor in 2011. They project that the market will grow at 7% to 8% per year, and only 19% of Indian rural farming households that can afford a tractor have as yet purchased a unit.
Designs that allow multi-functional use, adapted to local needs and rural constraints, are experiencing higher demands.
Market Share:
Five companies account for over 80% of the market share
Mahindra and Mahindra (largest at 42.5% share)
TAFE with 20%
Rest
Escorts,
ITL-Sonalika
John Deere.
Current manufacturers of tractors in India
ACE Tractors
Action Construction Equipment Limited (ACE) began manufacturing of Tractors in 2009 by launching two models in 35 / 45 HP categories. At present it is manufacturing 3 models by introducing 55 HP models in 2011. And also manufactured crains, harvester etc. In Oct.2013 ACE Tractors reached a milestone of selling 2000 tractors in India and Nepal. ACE has its manufacturing plants in Faridabad (Haryana), Kashipur/Bajpur (Uttrakhand).
Agri-King Tractors and Equipments Pvt. Ltd.
Established in 2010 at Majholi, Himachal Pradesh in Northern India, Agri King produces a few models of tractors, which seem to be based on Steyr Tractors or Basak Tractors . The Agri King T44 40 HP model, Agri King T54 50 HP model, and Agri King 20–55 50 HP model with improved 24 speed synchro-mesh transmission. All feature Kirloskar engines.
Agrotrack
Pauniya Tractors And Farm Equipment was founded in 2018 by C.A. Singh. Their history says AGROTRACK Tractor India was looking for company to assemble their tractors in India, and selected Pauniya. They assemble a limited number of models utilizing Kirloskar engines.
Akash
Akash Equipments & Machineries Pvt, Ltd began building tractors in 2010. They are based in Faridabad, Haryana, and only assemble a few different low-horsepower models.
Angad Tractors
Apollo Tractors
Apollo Tractors – Fieldtrack Earthmovers Pvt. Ltd began in 2017 in Kadi, Mehsana, India. It is a small manufacturer.
AutoNXT
AutoNxt Automation began in 2022 in Kalher, Bhiwandi, Maharashtra, and is building electric tractors for the Indiana market.
Captain Tractors Pvt. Ltd
Captain Tractors had been established in 1994 in Rajkot by joint efforts of two brothers Mr. G.T. Patel and Mr. M.T. Patel based from village Sanali dist. Amreli (Gujarat). Today Captain Tractors manufacture mini tractors from 15 to 30 HP.
Cellestial eMobility
Cellestial eMobility is another electric tractor manufacturer in India. They are based in Hyderabad.
Crossword Agro Industries
Located in Rajkot, India, Crossword manufactures small tractors under the Nissan, Atmak and Captain brand names. .
d.k. Champion
D.K. Diesels Pvt. Ltd was founded in 1998 and is based in the mini-tractor capital in India of Rajkot, Gujarat. They build mini-tractors up to smaller tractors, 10 hp-28 hp.
Darsh
DarshTrek and Darsh Belarus began in 2022 as a part of Darsha, Erisha Agritech Private Ltd., division of Rana Group. Darsh Belarus tractors are assembled and manufactured under license from MTZ and is based in New Delhi. DarshTrek tractors include some built by Captain Tractors, some electric, and others.
Eicher
In 1949, Eicher GoodEarth, was set up in India with technical collaboration with Gebr. Eicher of Germany, imported and sold about 1500 tractors in India. On 24 April 1959 Eicher came out with the first locally assembled tractor from its Faridabad factory and in a period from 1965 to 1974 became the first fully manufactured (100% indigenisation) tractor in India. In December 1987 Eicher Tractors went public and in June 2005 Eicher Motors Limited sold Eicher Tractors & Engines to a subsidiary of TAFE called TAFE Motors and Tractors Limited.
Eicher also produced tractors under the Euro Power and Eicher Valtra brands under license from Valtra, an AGCO brand.
Escorts
Escorts began local manufacture of Ford tractors in 1971 in collaboration with Ford, UK and total production climbed steadily to 33,000 in 1975, reaching 71,000 by 1980. Ford (Ford – New Holland) was sold in 1992. Ford Motor Company proper quit the tractors business, but the name was allowed to continue as per agreement until 2000, when Escorts relabelled its Ford models under the Escort brand. Escort manufactures produces construction and agriculture tractors in the 8-75 HP range and has already sold over 600,000 tractors. Its tractors are marketed under three brand names, Escort, Powertrac and Farmtrac.
In 2020 Kubota acquired 10% of Escorts, and is selling 40% of Kubota Agricultural Machinery India (KAI) to Escorts. In 2022, the ag company was renamed Escorts-Kubota Ltd, and tractors are also marketed under the Escorts-Kubota brand.
Farmer Tractor
Based in Rajkot, Gujarat, Farmer Tractor is focused on the production the Farmer Tractor DI 1200, using a Greaves four stroke, direct injection, 12 HP diesel engine.
HAV
HAV, or Hybrid Agri Vehicle, is a hybrid-engine tractor manufacturer based in Noida, Uttar Pradesh. Founded in 2020, they manufacture diesel & CNG – electric hybrid tractors.
Hercules tractors
Swift Auto Engg Solutions Pvt. Ltd manufacture the Hercules brand of tractors in India. It is based in Ballabhgarh, Haryana.
HMT Tractors
HMT is a large public sector unit and began manufacturing Agricultural Tractors in 1972 under the HMT brand name with technology acquired from Zetor of the Czech Republic. It manufactures its tractors in Pinjore, Panchkula in a large factory that also manufactures machine-tools, and Hyderabad It has a capacity of 20,000 tractors per annum. In the Machine-tool company is a large foundry. It produces tractors in a range from 25 HP to 75 HP. HMT has also exported tractors to the USA under the Zebra brand, which were marketed by Zetor distributors and dealers there. The company is controlled by the Ministry of Heavy industry that provides to the public its financial performance. Now the company is permanently closed.
HNT
HNT Pvt. Ltd (Hoshiar Nirvair Tractors Pvt Ltd) was founded in 2012 in Una, Himachal Pradesh. They manufacturer a range of tractors from 35 hp up to 75 hp.
Indo Farm
Indo Farm commenced commercial production of tractors in October 2000 at its plant located at Baddi in District Solan, Himachal Pradesh with technology acquired from Ursus of the Poland. Spread over an area of 34 acres, the plant started with the production of a single model. Within a decade of successful operations Indo Farm grew to a company having models in the range of 30 HP, 38 HP, 42 HP, 48 HP, 50 HP, 52 HP, 55 HP, 60 HP, 65 HP, 75 HP and 90 HP with many variants. Within a year of its operations, the company had successfully indigenized the engine components, manufacturing and assembly processes, and accordingly stopped import of engines. In 2008, the company diversified into manufacturing and marketing of Pick-N-Carry cranes of 9 tonnes – 20 tonnes capacity and has recently commenced production of mobile tower cranes too. It is now making engines for generator sets that are exported overseas.
John Deere
In 2000, John Deere set up production in a joint venture with Larsen & Toubro Ltd in Sanaswadi, in a rural area near Pune, Maharashtra. It was known as L&T John Deere Private Ltd, and manufactured tractors under the L&T – John Deere name for sale in India, and under the John Deere name for worldwide sales.
In 2005, Deere & Company acquired nearly all the remaining shares in this joint venture. The new enterprise, is known as John Deere Equipment Private Limited. The factory currently produces tractors in of 35, 38, 40, 42,45, 50, 55, 65, 75 and 89 HP capacities for domestic markets and for export to the US, Mexico, Turkey, North and South Africa, and South East Asia. Pune factory started to produce new 55 to 75 Hp 5003 series tractors for European market in 2008.
John Deere India Private Limited is a subsidiary of Deere & Company, USA in India. Its factory, located at Sanaswadi, Pune, manufactures 5000 Series agricultural tractors.
The Indian operations of Deere & Company include a technology center located at Magarpatta City Pune, John Deere Dewas (Indore MP) works, Jon Deere PDC Nagpur (MH) and John Deere Water Vadodara.
The technology center provides services in the areas of Information technology, engineering, supply management, embedded systems and technical authoring for company's operations worldwide.
John Deere Water, formed by the acquisitions of Plastro Irrigation Systems, T-Systems International, and Roberts Irrigation Products.
Mahindra Gujarat Tractor Limited (MGTL)
The company popularly known as Gujarat Tractors and its popular 60 hp model Hindustan 60 was established in 1959 as Tractors and Bulldozers Private Ltd and imported tractors. Manufacturing began in 1963, in collaboration Motokov-Praha (Zetor) of Czechoslovakia, and was known as Hindustan Tractors & Bulldozers Ltd. In 1967, it became Hindustan Tractors Ltd. The tractors were based on the Zetor tractor design and sold under the Hindustan brand. In 1978, the Gujarat, Indian government formed [ Gujarat Tractors] from the ailing company. In 1999, Mahindra Tractors purchased 60% of the company, and in 2001, completed purchasing the rest of the company, renaming it Mahindra Gujarat Tractors Ltd thus becoming part of Mahindra Group. The company is engaged in manufacturing of tractors in a range of 30–60 hp which are marketed under Farmplus and Shaktimaan brand.
Mahindra Gujarat Tractor Limited (MGTL) has its Head Office at Vadodara.
MGTL is an ISO 9001:2008 and OHSAS18001:2007 certified company. The company has a very good marketing network across India having 13 area offices and around 225 dealers.
In 2017, Mahindra Gujarat was renamed Gromax Agri Equipment (GAEL), and is using Trakstar as its tractor brand.
Mahindra Tractors
Mahindra Tractors is an international farm equipment manufacturer of Mahindra & Mahindra. In 2010, Mahindra became the largest selling tractor in the world. Mahindra's largest consumer base is in India, but with sales also focusing on China, North America and a growing base in Australia. The company is the largest manufacturer with about 25% of the market in India and has the capacity to build 150,000 tractors a year.
In 1963, M&M formed a joint venture with International Harvester to manufacture tractors carrying the Mahindra nameplate for the Indian market. Mahindra purchased the rights from International Harvester to manufacture their British designed International B-275 model which was also sold in USA as McCormick International. Mahindra Tractors sold about 85,000 units annually making it one of the largest tractor producers in the world.[5] To expand into the growing tractor market in China, Mahindra acquired majority stake in Jiangling.
Its sales in Gujarat are under the label Mahindra Gujarat and its sales in Punjab are under the label Swaraj. In 1999, Mahindra purchased 100% of Gujarat Tractors from the Government of Gujarat ??[9] and Mahindra purchased a 64.6% stake in Swaraj in 2004.
Mahindra Tractors started manufacturing 15HP tractor under the brand name Yuvraj in Rajkot in 2011. The plant in Rajkot is set up jointly by Deepak Diesel Pvt Ltd and Mahindra & Mahindra. The plant has a maximum capacity of 30000 tractors per year.
Mars Group
Originally established in 1976, the MARS Group is engaged in manufacturing/marketing of dump trucks, loaders, foggers, and agricultural tractors and attachments. Based in Lucknow, U.P., it began manufacturing two mini-tractor models under the Marshal name in 2005, Captain DI 2600 of 25 HP and Trishul MT DI 625 10 HP.
New Holland Agriculture
New Holland Ag's entry into India was facilitated by FIAT's acquisition of Ford-New Holland in 1991. By 1998 New Holland Ag. (India) completed the construction of a new plant in Noida, near New Delhi, with a capacity of 5000 tractors in the 35 – 75 hp range. In 1999, New Holland Ag's parent company FIAT bought 70% of holdings of Case Corporation and created Case New Holland Global (CNH one of the top three tractor/agricultural/construction machinery manufacturers in the world), the new holding company for New Holland Ag. (India). In 2000, the capacity of the Noida plant rose to 12,000 tractors per year and in 2007 the company manufactured 24,000 tractors for the domestic and export markets. New Holland India exports fully built tractors to 51 countries in Africa, Australia, South-East Asia, West Asia, North America and Latin America. The India plant of New Holland was originally built in 1998 to cater only to India domestic market. However, due to slow down of economy by year 2001–2002 and slump in domestic demand, it became a challenge to utilize the installed capacity of the factory. Hence the company started looking its market beyond India borders. By 2007 New Holland had increased its exports to 8000 units and was contributing over 50% of the company business. In 2007, this also made New Holland the second largest tractor exporter from India after John Deere.
Preet Tractors
Entrepreneur Mr. Hari Singh and his brother Mr. Gurcharan Singh laid the foundation of "Preet Agro Industries back in 1980 when they began initial production of straw reapers, threshers and other agricultural implements. The two launched their first tractor driven combine harvester in 1986. With a successful line of combine harvesters under their belt they began research and development for a tractor that led to their first and best known model "987". With excellent reliability and performance Preet continues to make remarkable impact not only in Indian farming community and other countries across the world.
Preet's manufacturing plant Patiala, Punjab, spanning 50,000 sq meters is producing low cost ad quality tractors offered in a range of 35 HP to 90 HP. Similarly the Combine harvesters are offered in 75 HP and 110 HP for multiple crops, including paddy, wheat, etc.
In 2022, Preet began marketing their tractors overseas using the Avenger brand.
SAME Deutz-Fahr (India) Private Ltd.
In 1996, SAME DEUTZ-FAHR set up production in a joint venture with Greaves Ltd in Ranipet, Tamil Nadu. It was known as SAME GREAVES TRACTOR Ltd, and manufactured tractors under the name SAME-Greaves for sale in India. In 2002, SAME DEUTZ-FAHR acquired nearly all the remaining shares in this joint venture. The new enterprise is known as SAME DEUTZ-FAHR India Private Ltd. The factory currently produces tractors in of 35 to 120HP capacities and Engines from 35 to 160 HP for domestic markets and International Markets.
SAME DEUTZ-FAHR (SDF) India Private Limited a subsidiary of SDF Group Italy since 2002. The Group manufacturers and sells tractor across the globe through its major brands SAME, Deutz-Fahr, Lamborghini, Hurlimann and Gregoire. SDF India sells its tractors in India through its brand Deutz-Fahr and the product range includes tractors from 35-80HP. SDF India has an established network of 220+ dealerships with service centres across India.
Solis Tractors (Solis-Yanmar)
In 2011 a joint venture between Yanmar Co. Ltd. and ITL (Sonalika-International Tractors Limited) was formed in to manufacture and market tractors in India and for export markets under the "Solis Yanmar" brand name. In the past, this company has built tractors for Claas and Renault, among others. Today it collaborates with the Japanese Yanmar and produces tractors for Landini. With a production of 120,000 units per year, Sonalika is one of the largest tractor manufacturers in the world. The Sonalika Group is an Indian multinational company headquartered in Hoshiarpur, India.
Solis offers a wide range of 2 and 4-wheel drive tractors from 30 HP (model 3016 SN) to 75 HP (7524 S).
Sonalika
International Tractors Limited was incorporated on 17 October 1987 and began manufacturing tractors designed by Central Mechanical Engineering Research Institute (CMERI). I. In 2000 ITL entered into a tie up with Renault Agricultural of France and began manufacturing Sonalika tractors. Sonalika is currently manufacturing models between 18 HP to 120 HP, and as well as the Renault CERES brand between 60HP to 90HP.
In 2005 Yanmar bought a 13 per cent stake in the company and began lifted production to 200 tractors per day. In 2013 the world's largest private investment company US based BlackRock purchased approximately 13% stake in ITL with the remaining 70 owned by founder Lachhman Das Mittal. In 2016 Yanmar purchased BlackRock's stake, bringing their stake to approximately 30%. In 2017 Sonalika began manufacturing Zetor Global brand tractors for Zetor.
Sonalika International tractors Ltd. is the youngest and the third largest tractor maker in India. Its integrated tractor manufacturing plant at Hoshiarpur has a capacity to produce 3 lakh units per annum. The company produces tractors in a range from 20HP to 120HP and has presence in more than 80 countries. Sonalika ITL has been recently felicitated by The Economic Times publication as an 'Iconic Brand of India'.
Standard
Standard Combine began building tractors in Barnala, Punjab, India. In Standard Tractors, tractors are being manufactured in the range of 35, 45, 50, 60, and 75 HP with respective model names: Standard 335, Standard 345, Standard 450, Standard 460, and Standard 475. Engines for all these tractor models, except the last one, are manufactured within the plant as 'Standard Engines', in specific names – SE 335, SE 345, SE 450 and SE 460, respectively. All the above-mentioned models of Standard Engines have shown compliance to the TREM-III emission norms, as have been verified by the ARAI. However, two new variants of tractor of 35 hp (Standard 335-I) and 45 hp (Standard 345-I), equipped with famous Perkins engines (assembled within the Standard Tractors plant), and two completely new models of tractor of 30 hp (Standard 330) and 40 hp (Standard 340) are on the verge to be launched. Besides these, three 3-wheelers (two passenger-carriers and one cargo), one 4-wheeler (cargo), a crane, an electric 3-wheeled mini-car, and two 2-wheelers (scooters) are either in the process of development or on the verge of launch from the Standard Tractor Division.
Swaraj Tractors
In the mid-sixties, with the Green Revolution triggering large-scale tractor usage, there was a need for the country to build sufficient indigenous capacity to meet this growing demand.
In 1965, the Central Mechanical Engineering Research Institute (CMERI), Durgapur initiated design and development of Swaraj Tractor based on indigenous know how. That is how the idea for development of what was to become Swaraj was initiated. The first prototype was ready in May 1967 and by April 1970, field experience of over 1,500 hours had been gained. At that point, it was decided to christen a name for the product – signifying Indian, easy to pronounce and signifying power and grace. The name 'Swaraj', was approved by the then Prime Minister, Mrs Indira Gandhi.
In 1970, the Government of Punjab acquired the Swaraj tractor's design and established Punjab Tractors Limited (PTL). The tractors were produced and sold under the brand name of Swaraj. In 2007, Mahindra & Mahindra Ltd. acquired majority stake in PTL, and in Feb 2009, it was merged into M&M as the Swaraj Division of Mahindra & Mahindra.
TAFE
Tractors and Farm Equipment Limited (TAFE) is the second largest tractor manufacturer in India. The company established in 1961 to manufacture and market Massey Ferguson tractors and related farm equipment in India. It is part of Amalgamations Group based in Chennai with Mallika Srinivasan as the chairman of the company.AGCO also owns 24% stake in TAFE. Tractors are built and sold in India under both the TAFE and Massey Ferguson brands, and exported under both brands as well. In 2005, TAFE bought the Eicher Motors tractor and engine division.
Traclaxx Tractors
Traclaxx Tractors Pvt. Ltd , formerly Forcetrac Tractors Private Limited was founded in 2014 in Ludhiana, Punjab by Darpan Dadu. They are a small volume, low horsepower tractor manufacturer and is part of BAX Intl. They may not still be in business as of 2023.
VST Tillers
VST Tillers was set up in 1967 in Bangalore, India. In collaboration with Mitsubishi Agricultural Machinery of Japan, they manufacture 18HP tractors under various brands, including Mitsubishi-Shakti, Shakti, Eurotrac-VST and Euro-Trac. They have been exported to Asia, the Middle East, Europe and the USA. In 2020, VST and Zetor set up a joint venture to manufacture tractors in India under the VST-Zetor brand.
Previous Indian Tractor Companies
Tractor companies that did not survive and were not acquired by other companies are:
Auto Tractors Ltd., Pratapgarh
Established in 1979, Auto Tractors Ltd. (ATL) had a manufacturing plant at Pratapgarh, Uttar Pradesh, and were making tractors with Leyland engines. It was established with 40% state money and the remainder an IDBI Bank loan. Production began in September 1981, but with severe supply problems and an outmoded product they only produced 2,380 tractors in their nearly ten years of existence. This was less than the projected production for the first two years alone. The company and assets were sold to automaker Sipani in 1991, who focused on producing diesel tractor engines (at over five times the rate of ATL themselves) but built some tractors as well.
After having been liquidated, the last of the company assets were offered for sale by the Uttar Pradesh state government in 2008.
Asian Tractors Ltd
Began building tractors in 1989 from their own designs.
Ford Tractors
Ford (formerly Ford Tractor Division) began producing Ford Tractors in India in 1972 with a tie up with Escorts. In 1986 Ford acquired New Holland and tractor operations was transferred to Ford-New Holland and made into an independent corporation. In 1991, Fiat began an arranged purchase of Ford-New Holland that was completed in 1993, ending Ford Motor Company's long history of tractor production. The deal required that New Holland/FIAT stop using the Ford name. New Holland India Pvt Ltd began production of tractors in India in 1998.
Harsha Tractors
In 1975, Harsha Tractors Ltd began manufacturing tractors in conjunction with Motoimport of Russia. Tractor production never amounted to much, and has since ceased.
Haryana Tractors Ltd
As a part of Pratap Steel Rolling Mills Ltd., Haryana began building tractors from their own designs in 1983.
Kirloskar Tractors
Founded in co-operation with Deutz-Fahr of Germany in 1974. It has since ceased to manufacture tractors. However, the company continues to manufacture engines under license from Deutz.
Pittie Tractors
Pittie Tractors was set up by a young and dynamic engineer – Shrikant Pittie and started out as Pittie Tools. The Pittie family are prominent industrialists in Pune and the family set up the first private industry in Pune – The Raja Bahadur Motilal Poona Mills Ltd. in 1893. Pittie Tractors indigenously developed and manufactured tractors and was well set to capture a large share of the market in India. However, due to an unfortunate labour strike at one of its critical vendors, followed by a similar strike at its own plant, the company lost nearly a year of production. As a result, the company fell into financial difficulty and ultimately had to wind-up operations.
United Auto Tractors Ltd.
Began in 1986 in conjunction with Uzina Tractorul of Romania.
Tractor Manufacturers Association
The Tractor Manufacturers' Association of India (TMA) is housed under The Confederation of Indian Industry (CII), New Delhi. Though not all manufacturers are members TMA is recognised as the main trade group representing the agricultural tractor industry in India. TR Kesavan, COO – Product Strategy and Corporate Relations, TAFE – Tractors and Farm Equipment Limited is the current President of TMA.
See also
List of tractor manufacturers – worldwide list
List of former tractor manufacturers – worldwide list
References
Agriculture in India
Tractors | Tractors in India | [
"Engineering"
] | 6,527 | [
"Engineering vehicles",
"Tractors"
] |
8,865,790 | https://en.wikipedia.org/wiki/International%20Congress%20of%20Quantum%20Chemistry | The International Congress of Quantum Chemistry (ICQC), is an international conference dedicated to the field of quantum chemistry. It is organized by the International Academy of Quantum Molecular Science. The first conference was held from July 4 to 10, 1973 in Menton, France. The first conference marked the "50th anniversary of the discovery of wave mechanics".
Past meetings
In chronological order:
Menton, France July 4–10, 1973
New Orleans (1976)
Kyoto (1979)
Uppsala (1982)
Montreal (1985)
Jerusalem (1988)
Menton (1991)
Prague (1994)
Atlanta (1997)
Menton (2000)
Bonn (2003)
Kyoto (2006)
Helsinki (2009)
Boulder (2012)
Beijing (2015)
Menton June 18–23 (2018)
Bratislava (2023)
Auckland (2026)
Papers from the Congresses have been published by the International Journal of Quantum Chemistry (IJQC).
References
Academic conferences | International Congress of Quantum Chemistry | [
"Physics",
"Chemistry"
] | 190 | [
"Quantum chemistry",
"Quantum mechanics",
"Theoretical chemistry",
" molecular",
"Atomic",
" and optical physics"
] |
8,865,843 | https://en.wikipedia.org/wiki/Loop%20modeling | Loop modeling is a problem in protein structure prediction requiring the prediction of the conformations of loop regions in proteins with or without the use of a structural template. Computer programs that solve these problems have been used to research a broad range of scientific topics from ADP to breast cancer. Because protein function is determined by its shape and the physiochemical properties of its exposed surface, it is important to create an accurate model for protein/ligand interaction studies. The problem arises often in homology modeling, where the tertiary structure of an amino acid sequence is predicted based on a sequence alignment to a template, or a second sequence whose structure is known. Because loops have highly variable sequences even within a given structural motif or protein fold, they often correspond to unaligned regions in sequence alignments; they also tend to be located at the solvent-exposed surface of globular proteins and thus are more conformationally flexible. Consequently, they often cannot be modeled using standard homology modeling techniques. More constrained versions of loop modeling are also used in the data fitting stages of solving a protein structure by X-ray crystallography, because loops can correspond to regions of low electron density and are therefore difficult to resolve.
Regions of a structural model that are predicted by non-template-based loop modeling tend to be much less accurate than regions that are predicted using template-based techniques. The extent of the inaccuracy increases with the number of amino acids in the loop. The loop amino acids' side chains dihedral angles are often approximated from a rotamer library, but can worsen the inaccuracy of side chain packing in the overall model. Andrej Sali's homology modeling suite MODELLER includes a facility explicitly designed for loop modeling by a satisfaction of spatial restraints method. All methods require an upload of the PDB file and some require the specification of the loop location.
Short loops
In general, the most accurate predictions are for loops of fewer than 8 amino acids. Extremely short loops of three residues can be determined from geometry alone, provided that the bond lengths and bond angles are specified. Slightly longer loops are often determined from a "spare parts" approach, in which loops of similar length are taken from known crystal structures and adapted to the geometry of the flanking segments. In some methods, the bond lengths and angles of the loop region are allowed to vary, in order to obtain a better fit; in other cases, the constraints of the flanking segments may be varied to find more "protein-like" loop conformations. The accuracy of such short loops may be almost as accurate as that of the homology model upon which it is based. It should also be considered that the loops in proteins may not be well-structured and therefore have no one conformation that could be predicted; NMR experiments indicate that solvent-exposed loops are "floppy" and adopt many conformations, while the loop conformations seen by X-ray crystallography may merely reflect crystal packing interactions, or the stabilizing influence of crystallization co-solvents.
Template Based Techniques
As mentioned above homology-based methods use a database to align the target protein gap with a known template protein. A database of known structures is searched for a loop that fits the gap of interest by similarity of sequence and stems (the edges of the gap created by the unknown loop structure). The success of this method largely depends on the quality of that alignment. Since the loop is the least conserved portion of a protein’s structure, the homology-based method cannot always find a known template that aligns with the target sequence. Fortunately, the template databases are always adding new templates so the problem of not being able to find an alignment is becoming less of an issue. Some programs that use this method are SuperLooper and FREAD.
Non-Template Based Techniques
Otherwise known as an ab initio method, non-template based approaches use a statistical model to fill in the gaps created by the unknown loop structure. Some of these programs include MODELLER, Loopy, and RAPPER; but each of these programs approaches the problem in a different manner. For example, Loopy uses samples of torsion angle pairs to generate the initial loop structure then it revises this structure to maintain a realistic shape and closure, while RAPPER builds from one end of the gap to the other by extending the stem with different sampled angles until the gap is closed. Yet another method is the “divide and conquer” approach. This involves subdividing the loop into 2 segments and then repeatedly dividing and transforming each segment until the loop is small enough to be solved. Even with all these methods non-template based approaches are most accurate up to 12 residues (amino acids within the loop).
There are three problems that arise when using a non-template based technique. First, there are constraints that limit the possibilities for local region modeling. One such constraint is that loop termini are required to end at the correct anchor position. Also, the Ramachandran space cannot contain a backbone of dihedral angles. Second, a modeling program has to use a set procedure. Some programs use the “spare parts” approach as mentioned above. Other programs use a de novo approach that samples sterically feasible loop conformations and selects the best one. Third, determining the best model means that a scoring method must be created to compare the various conformations.
See also
Chung SY, Subbiah S. (1996.) A structural explanation for the twilight zone of protein sequence homology" Structure 4: 1123–27.
Fiser A, Gian Do RK, Sali A. (2000) Modeling of loops in protein structures" Protein Science 9: 1753-73
Ko J. et al. The FALC-Loop web server for protein loop modeling" Nucleic Acids Research 39, W210-W214 (2011).
Lee J, Lee D, Park H, Coutsias EA, Seok C. "Protein loop modeling by using fragment assembly and analytical loop closure. Proteins: Structure, Function, and Bioinformatics 78, 1-9 (2010).
Mount DM. (2004). Bioinformatics: Sequence and Genome Analysis 2nd ed. Cold Spring Harbor Laboratory Press: Cold Spring Harbor, NY.
Soto C. et al. "Loop modeling: Sampling, filtering, and scoring. Proteins: Structure, Function, and Bioinformatics 70, 1-10 (2008).
Tang K., Zhang J., Liang J. (2014) Fast Protein Loop Sampling and Structure Prediction Using Distance-Guided Sequential Chain-Growth Monte Carlo Method. PLOS Computational Biology 10 (4), e1003539.
References
External links
MODLOOP, public server for access to MODELLER's loop modeling facility
RAPPER, public server for access to RAPPER’s protein modeling facility
SuperLooper2, SuperLooper2 homepage
FALC-Loop, FALC-Loop homepage
DiSGro, DiSGro homepage
Bioinformatics
Protein methods
Protein structure | Loop modeling | [
"Chemistry",
"Engineering",
"Biology"
] | 1,429 | [
"Biochemistry methods",
"Biological engineering",
"Protein methods",
"Protein biochemistry",
"Bioinformatics",
"Structural biology",
"Protein structure"
] |
8,866,863 | https://en.wikipedia.org/wiki/Pneumococcal%20vaccine | Pneumococcal vaccines are vaccines against the bacterium Streptococcus pneumoniae. Their use can prevent some cases of pneumonia, meningitis, and sepsis. There are two types of pneumococcal vaccines: conjugate vaccines and polysaccharide vaccines. They are given by injection either into a muscle or just under the skin.
The World Health Organization (WHO) recommends the use of the conjugate vaccine in the routine immunizations given to children. This includes those with HIV/AIDS. The recommended three or four doses are between 71 and 93% effective at preventing severe pneumococcal disease. The polysaccharide vaccines, while effective in healthy adults, are not effective in children less than two years old or those with poor immune function.
These vaccines are generally safe. With the conjugate vaccine about 10% of babies develop redness at the site of injection, fever, or change in sleep. Severe allergies are very rare.
Whole-cell vaccinations were developed alongside characterisation of the subtypes of pneumococcus from the early 1900s.
The first pneumococcal vaccine was developed in the 1980s. It is on the World Health Organization's List of Essential Medicines.
Recommendations
Worldwide
Pneumococcal vaccines Accelerated Development and Introduction Plan (PneumoADIP) is a program to accelerate the evaluation and access to new pneumococcal vaccines in the developing world. PneumoADIP is funded by the Global Alliance for Vaccines and Immunization (GAVI). Thirty GAVI countries have expressed interest in participating by 2010. PneumoADIP aims to save 5.4 million children by 2030.
A pilot Advance Market Commitment (AMC) to develop a vaccine against pneumococcus was launched by GAVI in June 2009 as a strategy to address two of the major policy challenges to vaccine introduction: a lack of affordable vaccines on the market, and insufficient commercial incentives to develop vaccines for diseases concentrated in developing countries. Under the terms of an AMC, donors make a legally binding guarantee that, if a future vaccine is developed against a particular disease, they will purchase a predetermined amount at an agreed-upon price. The guarantee is linked to safety and efficacy standards that the vaccine must meet and is structured in a way to allow several firms to compete to develop and produce the best possible new product. AMCs reduce risk to donor governments by eliminating the need to fund individual research and development projects that may never produce a vaccine. If no company produces a vaccine that meets the predetermined standards, governments (and thus their taxpayers) spend nothing. For the bio-pharmaceutical industry, AMCs create a guaranteed market, with a promise of returns that would not normally exist. For developing countries, AMCs provide funding to ensure that those vaccines will be affordable once they have been developed. It is estimated that the pneumococcal AMC could prevent more than 1.5 million childhood deaths by 2020.
Doctors Without Borders has criticized GAVI's pneumococcal AMC for not encouraging innovation, discouraging competition from new market entrants, and raising vaccine costs. They said that it had allowed Pfizer and GlaxoSmithKline to maintain a duopoly while making it more difficult for the Serum Institute of India to sell their cheaper vaccine. The duopoly allowed price discrimination; somewhat higher prices for GAVI, and unaffordable prices (about ten time the GAVI price) for middle-income countries too rich for GAVI aid. The pneumococcal program (unlike previous market-shaping programs from GAVI) did not include any mechanism for increasing competition.
The Humanitarian Mechanism makes the pneumococcal vaccine available to humanitarian actors (but not governments) at a lower-than-normal price during humanitarian emergencies.
Belgium
The national vaccination program started vaccinating newborns in 2004 with the 7-valent pneumococcal conjugate vaccine (PCV 7). This was changed into the 13-valent conjugate (PCV 13) in 2011. The switch to the 10-valent conjugate (PCV 10) was made in July 2015 in Flanders and May 2016 in Wallonia. In late 2020 a start was made with the vaccination of care home residents with the 23-valant pneumococcal polysaccharide vaccine (PPV 23).
Canada
The Public Health Agency of Canada's general recommendations are 13-valent pneumococcal conjugate vaccine (PCV 13) vaccine for children aged 2 months to 18 years and 23-valent pneumococcal polysaccharide vaccine (PPV 23) vaccine for adults.
India
In May 2017, the Government of India decided to include the pneumococcal conjugate vaccine in its Universal Immunization Programme.
The Netherlands
The national vaccination program started including the pneumococcal vaccine for newborns in April 2006.
The Health Council advised in 2018 that those who are over the age of 60 should also be vaccinated on a 5-year recurring schedule. The resulting program from this, NPPV, started at the end of 2020.
Health authorities reported in December 2020 that former COVID-19 patients also have an indication for this vaccine because of the damage their lungs incurred. Vaccinating this group is not part of the NPPV program.
South Africa
The 7- and 13-valent pneumococcal conjugate vaccines (PCV7 and PCV13) were introduced into the National Expanded Program on Immunization (EPI) in South Africa in 2009 and 2011, respectively. South Africa became the first African country – and the first nation in the world with a high HIV prevalence – to introduce PCV7 into its routine immunization program. Rates of invasive pneumococcal disease (IPD) – including cases caused by antibiotic-resistant bacteria – have fallen substantially in South Africa following the introduction of PCV7. Among children under two years of age, the overall incidence of IPD declined nearly 70% after PCV introduction, and rates of IPD caused by bacteria specifically targeted by the vaccine decreased nearly 90%. Due to the indirect protection conferred by herd immunity, a significant decline in IPD in children and in unvaccinated adults has also been shown.
Pneumovax 23 is used for all ages and, according to the enclosed patient information leaflet, has a reported 76% to 92% protective efficacy (pneumococcal types 1, 2, 3, 4, 5, 6B**, 7F, 8, 9N, 9V**, 10A, 11A, 12F, 14**, 15B, 17F, 18C, 19A**, 19F**, 20, 22F, 23F** and 33F** are included, where ** indicates drug-resistant pneumococcal infections; these are the 23 most prevalent or invasive pneumococcal types of Streptococcus pneumoniae).
United Kingdom
It was announced in February 2006, that the UK government would introduce vaccination with the conjugate vaccine in children aged 2, 4 and 13 months. This included changes to the immunisation programme in general. In 2009, the European Medicines Agency approved the use of a 10 valent pneumococcal conjugate vaccine for use in Europe. The 13-valent pneumococcal vaccine was introduced in the routine immunization schedule of the UK in April 2010.
United States
In the United States, a heptavalent pneumococcal conjugate vaccine (PCV 7) (Prevnar) was recommended for all children aged 2–23 months and for at-risk children aged 24–59 months in 2000. The normal four-dose series is given at 2, 4, 6, and 12–14 months of age. In February 2010, a pneumococcal conjugate vaccine that protects against an additional six serotypes was introduced (PCV 13/brand name: Prevnar 13) and can be given instead of the original Prevnar. In June 2021, a pneumococcal conjugate vaccine which protects against 20 serotypes was approved with the brand name Prevnar 20. In April 2023, the FDA approved the use of Prevnar 20 vaccine to prevent pneumococcal disease in children aged six weeks to 17 years.
Pneumovax 23 (pneumococcal vaccine polyvalent) was approved for medical use in the United States in 1983.
Vaxneuvance (pneumococcal 15-valent conjugate vaccine) was approved for medical use in the United States in June 2021.
Capvaxive (pneumococcal 21-valent conjugate vaccine) was approved for medical use in the United States in June 2024.
In October 2024, the Centers for Disease Control and Prevention (CDC) updated its recommendations for the pneumococcal vaccination and recommends routine pneumococcal vaccination for all children younger than 5 years of age and all adults 50 years of age or older.
Mechanism
Polysaccharide vaccine
The pneumococcal polysaccharide vaccine most commonly used today consists of purified polysaccharides from 23 serotypes (1, 2, 3, 4, 5, 6b, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19A, 19F, 20, 22F, 23F, and 33F). Immunity is induced primarily through stimulation of B-cells which release IgM without the assistance of T cells.
This immune response is less robust than the response provoked by conjugated vaccines, which has several consequences. The vaccine is ineffective in children less than 2 years old, presumably due to their less mature immune systems. Non-response is also common amongst older adults. Immunity is not lifelong, so individuals must be re-vaccinated at age 65 if their initial vaccination was given at age 60 or younger. Since no mucosal immunity is provoked, the vaccine does not affect carrier rates, promote herd immunity, or protect against upper or lower respiratory tract infections. Finally, provoking immune responses using unconjugated polysaccharides from the capsules of other bacteria, such as H. influenzae, has proven significantly more difficult.
Conjugated vaccine
The pneumococcal conjugate vaccine consists of capsular polysaccharides covalently bound to the diphtheria toxoid CRM197, which is highly immunogenic but non-toxic. This combination provokes a significantly more robust immune response by recruiting CRM197-specific type 2 helper T cells, which allow for immunoglobulin type switching (to produce non-IgM immunoglobulin) and production of memory B cells. Among other things, this results in mucosal immunity and the eventual establishment of lifelong immunity after several exposures. The main drawbacks to conjugated vaccines are that they only protect against a subset of the serotypes covered by the polysaccharide vaccines.
depitte, J.; Gove, Sandy; Breiman, Robert F.
Research
Due to the geographic distribution of pneumococcal serotypes, additional research is needed to find the most efficacious vaccine for developing-world populations. In a previous study, the most common pneumococcal serotypes or groups from developed countries were found to be, in descending order, 14, 6, 19, 18, 9, 23, 7, 4, 1, and 15. In developing countries, the order was 6, 14, 8, 5, 1, 19, 9, 23, 18, 15 and 7. In order to further pneumococcal vaccine research and reduce childhood mortality, five countries and the Bill & Melinda Gates Foundation established a pilot Advance Market Commitment for pneumococcal vaccines worth US$1.5 billion. Advance Market Commitments are a new approach to public health funding designed to stimulate the development and manufacture of vaccines for developing countries.
There is research into producing vaccines that can be given into the nose rather than by injection.
The development of serotype-specific anticapsular monoclonal antibodies has also been researched in recent years. These antibodies have been shown to prolong survival in a mouse model of pneumococcal infection characterized by a reduction in bacterial loads and a suppression of the host inflammatory response. Additional pneumococcal vaccine research is taking place to find a vaccine that offers broad protection against pneumococcal disease.
, pneumonia vaccines target up to 23 forms of the bacterium that cause pneumonia with a new version under development covering 72 strains of the bacterium.
References
Further reading
External links
Vaccines
World Health Organization essential medicines (vaccines)
Wikipedia medicine articles ready to translate | Pneumococcal vaccine | [
"Biology"
] | 2,761 | [
"Vaccination",
"Vaccines"
] |
8,867,314 | https://en.wikipedia.org/wiki/Stefan%20number | The Stefan number (St or Ste) is defined as the ratio of sensible heat to latent heat. It is given by the formula
where
cp is the specific heat,
cp is the specific heat of solid phase in the freezing process while cp is the specific heat of liquid phase in the melting process.
∆T is the temperature difference between phases,
L is the latent heat of melting.
It is a dimensionless parameter that is useful in analyzing a Stefan problem. The parameter was developed from Josef Stefan's calculations of the rate of phase change of water into ice on the polar ice caps and coined by G.S.H. Lock in 1969. The problems origination is fully described by Vuik and further commentary on its place in Josef Stefan's larger career can be found in
Same number exist for vapor to liquid phase change, Nombre de Jakob.
Notes
Dimensionless numbers of thermodynamics | Stefan number | [
"Physics",
"Chemistry"
] | 185 | [
"Thermodynamic properties",
"Physical quantities",
"Dimensionless numbers of thermodynamics"
] |
8,867,764 | https://en.wikipedia.org/wiki/Canadian%20Sport%20Parachuting%20Association | The Canadian Sport Parachuting Association (CSPA), through affiliation with the Aero Club of Canada (ACC), is Canada's representative to the Fédération Aéronautique Internationale (FAI) and the International Parachuting Commission (IPC). Thus, the CSPA is the official sport organization for sport parachuting in Canada.
Objectives
The stated objective of the CSPA is to "promote safe and enjoyable sport parachuting through cooperation, adherence to self-imposed rules, and recommendations".
Skydivers and skydiving companies that wish to be members of the CSPA must adhere to the established Basic Safety Rules throughout their parachuting career. Such rules include minimum opening altitudes for certain levels of experience, mandatory equipment, clear weather conditions for jumping, reserve repack due dates, general operational requirements, etc. These Basic Safety Rules significantly reduce the risk of accidents for individual skydivers, skydiving companies, and the sport. A Canadian Drop Zone must adhere to all of these safety rules to be a member of the CSPA.
The CSPA also has recommended procedures and instructor qualification requirements. A Canadian skydiver starts with a solo license and then progresses to the A, B, C, and D licenses. The CSPA requires that skydivers keep a log of every jump signed by another jumper and submit that logbook to acquire these qualifications.
The CSPA constantly updates all programs and initiatives to adapt to increasing incidents and changes in technology. Every member (skydiver or skydiving company) must implement all changes to remain members.
CanPara
The CSPA publishes CanPara, a bimonthly bilingual publication devoted to informing the Canadian skydiving community of important activities and events in Canadian and worldwide skydiving. CanPara is produced by Annaleah McAvoy and Vic Lefrançois.
Organization
The CSPA comprises Registered Participants and Member Groups. The Board of Directors will consist of no less than three and no more than seven Directors.
National Office Staff:
Executive Director: Michelle Matte-Stotyn
Executive Secretary: Judy Renaud
There are several committees and officers that assist the BoD:
Three Standing Committees:
Technical & Safety Committee
Coaching Working Committee
Competition & National Teams Committee.
Ad-hoc committees (a sampling):
CanPara - Bi-Monthly, bilingual Magazine
Comp./Dev - Competition Development
GRC - Government Regulatory Committee
IT - Information Technology
LTAD - Long Term Athlete Development
See also
Parachute
Parachuting
Parachute rigger
Canadian Airborne Forces Association
SkyHawks Parachute Team
United States Parachute Association
References
2006 Parachute Information Manual Part 1. CSPA
External links
Canadian Sport Parachuting Association (CSPA) website
CSPA Coaching Working Committee
Sport Parachuting Association
Parachuting organizations
Parachuting
Fédération Aéronautique Internationale
1956 establishments in Canada | Canadian Sport Parachuting Association | [
"Engineering"
] | 565 | [
"Fédération Aéronautique Internationale",
"Aeronautics organizations"
] |
8,867,778 | https://en.wikipedia.org/wiki/Pilot-operated%20relief%20valve | Like other pressure relief valves (PRV), pilot-operated relief valves (PORV) are used for emergency relief during overpressure events (e.g., a tank gets too hot and the expanding fluid increases the pressure to dangerous levels). PORV are also called pilot-operated safety valve (POSV), pilot-operated pressure relief valve (POPRV), or pilot-operated safety relief valve (POSRV), depending on the manufacturer and the application. Technically POPRV is the most generic term, but PORV is often used generically (as in this article) even though it should refer to valves in liquid service.
In conventional PRVs, the valve is normally held closed by a spring or similar mechanism that presses a disk or piston on a seat, which is forced open if the pressure is greater than the mechanical value of the spring. In the PORV, the valve is held shut by piping a small amount of the fluid to the rear of the sealing disk, with the pressure balanced on either side. A separate actuator on the piping releases pressure in the line if it crosses a threshold. This releases the pressure on the back of the seal, causing the valve to open.
The essential parts of a PORV are a pilot valve (or control pilot), a main valve, a pilot tube, the dome, a disc or piston, and a seat. The volume above the piston is called the dome.
Mode of functioning
The pressure is supplied from the upstream side (the system being protected) to the dome often by a small pilot tube. The downstream side is the pipe or open air where the PORV directs its exhaust. The outlet pipe is typically larger than the inlet. , , , , are some common sizes.
The upstream pressure tries to push the piston open but it is opposed by that same pressure because the pressure is routed around to the dome above the piston. The area of the piston on which fluid force is acting is larger in the dome than it is on the upstream side; the result is a larger force on the dome side than the upstream side. This produces a net sealing force.
The pressure from the pilot tube to the dome is routed through the actual control pilot valve. There are many designs but the control pilot is essentially a conventional PRV with the special job of controlling pressure to the main valve dome. The pressure at which the control pilot relieves is the functional set pressure of the PORV. When the pilot valve reaches set pressure it opens and releases the pressure from the dome. The piston is then free to open and the main valve exhausts the system fluid. The control pilot opens either to the main valve exhaust pipe or to atmosphere.
Snap acting At set pressure the valve snaps to full lift. This can be quite violent on large pipes with significant pressure. The pressure has to drop below the set pressure in order for the piston to reseat (see blowdown in relief valve article).
Modulating The pilot is designed to open gradually, so that less of the system fluid is lost during each relief event. The piston lifts in proportion to the overpressure. Blowdown is typically short.
Comparison to conventional pressure relief valves
Advantages
Smaller package on the larger pipe sizes.
More options for control.
Seals more tightly as the system pressure approaches but does not reach set pressure.
Control pilot can be mounted remotely.
Some designs allow for changes in orifice size within the main valve.
Can be used in engines.
Higher Operating-to-Set Pressure ratio.
Disadvantages
More complex, resulting in various fail-open failure modes.
More expensive at smaller sizes (starts to even out as pipe size increases).
Small parts in pilot valve are sensitive to contaminant particles.
Soft goods typically installed in pilot valves cannot withstand higher temperature fluids.
See also
Three Mile Island accident
Relief valve
Safety valve
References
Safety valves | Pilot-operated relief valve | [
"Engineering"
] | 787 | [
"Industrial safety devices",
"Safety valves"
] |
8,867,983 | https://en.wikipedia.org/wiki/Tie%20%28cavity%20wall%29 | The tie in a cavity wall is a component used to tie the internal and external walls (or leaves)—constructed of bricks or cement blocks—together, making the two parts to act as a homogeneous unit. It is placed in the cavity wall during construction and spans the cavity. The ends of the tie are designed to lock into the mortar. Also incorporated into the design of the tie is means of preventing water transfer from the outer to the inner leaves. In flat ties, this can be a twist. In wire ties, this can be corrugations formed in the wire or again a twist.
Background
Cavity walls often have insulation in the cavity which may either partially or fully fill the cavity. Partial fill insulation systems require specialized ties or clips to keep the insulation in position. A vapour barrier may be necessary on the inner wall to prevent interstitial condensation. This is often incorporated into the cavity wall insulation system. The spacing of ties is laid down in building regulations, though there may be variations with specialised blocks. Additional ties are used around window and door openings. Improper installation may lead to water damage or fungus formation within the cavity, leading to structural and health hazards.
Ties are exposed to water and chemical attack from cement. They were traditionally made of galvanized steel, the fishtail tie being the most common. On high quality work, ties were occasionally made of bronze. In the mid-twentieth century, wire ties were widely used, again made from galvanized steel wire. As time has passed, many galvanized steel ties have deteriorated due to moisture in the outer leaf of brickwork. The corrosion may force apart the cement joints and even result in the collapse of walls if no remedial action is taken. Any cracks appearing in cavity walls dating from the twentieth century need to be investigated before irremediable damage ensues. Horizontal cracking is especially suspect. Failed ties have to be isolated and substitute specialist ties installed by drilling through inner and outer leaves from outside the building. The replacement ties may be fixed mechanically or with special adhesives.
Galvanized steel ties are no longer in use for this reason. For a brief period, plastic ties were used but were not satisfactory. Modern practice is to use stainless steel ties.
Cavity walls were traditionally spaced 2"(50mm) apart. Due to the need for thicker insulation in exterior walls these days, a range of longer ties are now available so that cavities of up to 6"(150mm) can be constructed.
Types of ties
Ties in a cavity wall are typically made of iron, steel, or plastic; though figures are various. Basically, a tie has ring to fasten with mortar on both end like a bow. Ties would be selected by type of masonry, the cavity width, and so on.
Typically, ties in a cavity wall are double triangular shape (like a bow), though, depending on the existence of another layer (e.g. insulation sheet) at the cavity, which fills the cavity partially, ties include retaining discs or rods.
Tie failure
Failure of ties is an increasing problem with cavity wall ties made from galvanized steel. It arises when the galvanizing is not of sufficient quality and the outer leaf of the cavity wall allows water penetration, usually due to porous brick/blockwork. If the tie rusts, the swelling effect may cause horizontal, external cracks to appear in the wall. Frost action can swiftly enlarge these cracks to cause damage.
Tie corrosion
Since ties in a cavity wall are typically made of metal (iron or steel), they are prone to corrode over time. When metal corrodes, it expands its size, causing ties to lift up from the brickwork. Cracks caused by vertical loads leave parts of buildings vulnerable to corrosion, such as eaves and gable walls above purlin positions, or placed directly beneath openings, where the weight on brickwork is light. Over the time, cracks appear from the top of the wall and extend downward.
Cracks due to tie corrosion at the cavity wall are horizontal and tend to occur at the location of wall ties, normally 6 courses apart. The corrosion causes the walls to detach and tilt, resulting in the outer wall snapping outward. The inner wall is held in place by the added support of floor joists. At the gable wall, inner walls without these supporting joists, bow inwards. By avoiding several factors accelerating corrosion, it will last more than 60 years.
Acceleration factors of tie corrosion
Due to its materiality of the tie, its corrosion is related to the extent of the exposure at acidic substances. The major factors of the corrosion are:
Acidic black ash mortar
Exposure (coastal or general)
Coastal areas (salt in the atmosphere)
Industrial areas (acid rain)
Cavity wall insulation
Cement-based mortar, giving an alkaline environment for cavity wall ties, has been used since the Second World War. Alkaline environment is beneficial for ties protecting from acid and procrastinating the corrosion process. Before cement-based mortar, lime-based one was used, which does not present an alkaline environment. Therefore, the majority buildings with wall tie corrosion are built before the Second World War. An alkaline degree gets weaker while exposed at acidic rain over the time.
Moreover, metal corrosion is a chemical reaction that the reaction rate is triggered by water and heat. Thus, some say that cavity wall insulation enhance the ability to grab water longer, so that the environment of the ties damper. Accordingly, the South or South West elevations warmed by the sunlight are warmer, letting ties more at risk for this type of corrosion.
See also
Anchor plate
Cavity wall
External links
Holland, Malcolm. Practical Guide to Diagnosing Structural Movement In Buildings. Hoboken: Wiley, 2012.
Whittemore, Herbert L. Structural Properties of a Brick Cavity-Wall Construction Sponsored by the Brick Manufacturers Association of New York, Inc.. Washington, D.C.: U.S. Dept. of Commerce, National Bureau of Standards, 1939.
Wall Ties, NHBC Standards online Homepage
What is Wall Tie?, Ancon Building products company Homepage
What are Wall Ties?: by Adrian Dawson, Certified surveyors of remedial treatments C.S.R.T.
References
Building engineering | Tie (cavity wall) | [
"Engineering"
] | 1,279 | [
"Building engineering",
"Civil engineering",
"Architecture"
] |
8,868,004 | https://en.wikipedia.org/wiki/Paracaspase | Paracaspases (human: MALT1) are members of the C14 family of cysteine proteases. Paracaspases are proteins related to caspases present in animals and slime mold, in contrast to metacaspases, which are present in plants, fungi, and "protists". The phylogenetic distribution is a bit confusing, since slime mold diverged earlier than the animal/fungal split.
Paracaspase has been first identified in a recurrent t(11;18)(q21;q21) chromosomal translocation associated with a subset of MALT lymphoma. This leads to a fusion oncoprotein consisting of the carboxyl terminus of MALT1 and the amino terminus of c-IAP2. Paracaspases are more similar to caspases than metacaspases are, indicating that this group of proteases diverged from caspases from a common metacaspase ancestor.
Structure and Evolution
Most non-metazoan paracaspases found in amoebas or bacteria are "type 2" paracaspases with only a caspase-like domain. The animal paracaspases are most likely not directly related to the amoeba paracaspase. It is currently unclear whether the paracaspases (and caspases) found in eukaryotes are a result from several (at least 2) independent horizontal gene transfer events from prokaryotes or if there has been a convergent evolution of (para)caspases evolved from the metacaspases in several different organisms within the eukaryotes.
Animals
"Type 2"
The "type 2" paracaspases in animals represent the ancestral form which only consists of a caspase-like domain. This form of paracaspase can be found in ctenophora, trichoplax, sponges and cnidarians. Cnidarians also have "type 1" paracaspases.
"Type 1"
The "type 1" paracaspases are characterized by a MALT1-like domain composition with a death domain, immunoglobulin-like domains and a caspase-like domain. The "type 1" paracaspases first originated sometime before the last common ancestor of the bilaterans and cnidaria, indicating that "type 1" paracaspases originated during the ediacaran period. The jawed vertebrates (starting from sharks) have 3 paralogs: PCASP1, PCASP2 and PCASP3. PCASP3 is the ancestral copy and can be found in all deuterostomes, like sea urchin, lancelets, tunicates and lampreys (a non-jawed vertebrate). Notably, mammals have lost PCASP2 and PCASP3 and only have PCASP1 (MALT1). The non-deuterostome invertebrate type 1 paracaspase closest related to PCASP3 can surprisingly be found in molluscs, which could indicate that there were 2 paralog type 1 paracaspases present in the first bilaterans (like in cnidarians), and that different bilateran lineages have kept one or the other paralog.
Known functions
Amoebas
The paracaspase in Dictyostelium seems to regulate osmotic stress tolerance by vacuolar expansion.
Animals
Paracaspase in animals has mostly been studied in humans and mice (see: MALT1), where it plays a major role in several pro-inflammatory pathways in innate- and adaptive- immunity. The distantly related zebrafish PCASP3 show conserved MALT1-like activity in NF-kappaB activation and protease substrate specificity, indicating that these functions were present in the last common ancestor of the three vertebrate paracaspase paralogs. There are also indications that paracaspase is involved in immune- and NF-κB signaling also in invertebrates.
See also
The Proteolysis Map
MALT1
Caspase
Metacaspase
MALT lymphoma
References
Programmed cell death
Eukaryote proteins
EC 3.4.22 | Paracaspase | [
"Chemistry",
"Biology"
] | 891 | [
"Senescence",
"Programmed cell death",
"Signal transduction"
] |
8,868,030 | https://en.wikipedia.org/wiki/Metacaspase | Metacaspases are members of the C14 class of cysteine proteases and thus related to caspases, orthocaspases and paracaspases. The metacaspases are arginine/lysine-specific, in contrast to caspases, which are aspartate-specific.
Structure and Phylogenetic distribution
Prokaryotes
In archea and bacteria, there are several metacaspases with a wide range of domain organizations. Based on the prokaryote metacaspase diversity, orthocaspases can be considered a sub-class of metacaspases. Common for both metacaspases and orthocaspases classes is their specificity for basic residues (arginine or lysine) in the P1 position. At this moment, no structural variants have been reported where the substrate specificity would change to an acidic residue (aspartic acid), like in true caspases.
Eukaryotes
Metacaspases are found in plants, fungi, and "protists", but not in slime mold or animals.
Viruses
Viral metacaspases, which may have implications in rewiring host metabolism to enhance
infection, are widespread in the ocean.
Type I
Type I metacaspases are characterized by an amino-terminal proline or glutamine rich LSD zinc finger-like domain. This type can be found in prokaryotes and eukaryotes other than animals.
Type II
Type II is found only in certain green algae and land plants, with one recent exception where both type I and type II metacaspases were found in the genome of Monosiga brevicollis (Choanoflagellate), possibly as a result of an unusual horizontal gene transfer between two eukaryotes.This group is characterized by long linker region and the absence of an amino-terminal pro-domain.
Known functions
In an analogous manner to caspases, metacaspases induce programmed cell death in both plants and fungi (yeast).
References
See also
The Proteolysis Map
MALT1
Programmed cell death
Eukaryote proteins
Bacterial proteins
EC 3.4.22 | Metacaspase | [
"Chemistry",
"Biology"
] | 458 | [
"Senescence",
"Programmed cell death",
"Signal transduction"
] |
8,868,214 | https://en.wikipedia.org/wiki/Uttara%20Bh%C4%81drapad%C4%81 | Uttara Bhādrapadā or Uttṛṭṭāti (Devanagari: उत्तरभाद्रपदा) is the twenty-sixth nakshatra in Hindu astrology, corresponding to γ Pegasi and α Andromedae. It is ruled by Shani, the deity identified with the planet Saturn.
Under the beliefs of electional astrology, Uttara Bhādrapadā is a Fixed constellation, meaning that while it is prominent, it is a good time to build houses, found communities or engage in other activities related to permanence, stability and structure.
Uttara Bhādrapadā is represented by dualistic imagery, often two legs of a bed. Other common symbols include a two-headed man, or twins. The Ahirbudhnya, a serpentine or draconian creature, is the deity which oversees Uttara Bhādrapadā.
Male Natives:
Physical features:
Most attractive and innocent looking person. There is an inherent magnetically force in his look. If he looks at a person with a mild smile, rest assure, that person will be his slave.
Character and general events:
He keeps equal relationship with high and low people i.e. irrespective of the status of the person. He has a spot-less heart. He does not like to give troubles to others. The only drawback noticed in this native in the behavioral field is that temper is always on the tip of his nose. However, such short-temper is not of a permanent nature. He will not hesitate to sacrifice even his life to those who love him. At the same time once he is hurt he will become a lion. He has wisdom, knowledge, and personality.
He is expert in delivering attractive speeches. He is capable of vanquishing his enemies and attains fairly high position.
Education and sources of earnings / profession:
He can attain mastery over several subjects at the same time. Even if he is not academically much educated, his expression and knowledge put forward to the world will equal to that of highly educated persons. He is much interested in fine arts and has ability to write prolonged articles or books.
In the work field, he can shine well due to his extraordinary capacity and capability. Laziness is a remote question for him. Once he opts to undertake a job he cannot turn back till that job is completed. Even in the case of utter failure he is not desperate. If he is employed he will reach to the top. In most of the cases it has been noticed that even if this Nakshatra born persons are employed initially in the lower or middle level positions, they later on reach to a good position and they always receive reward and praise from others.
Family life:
While he keeps praising his father on the one side due to the prominent personality and religious rigidity of his father, he cannot virtually derive any benefit from his father. He leads a neglected childhood. He is normally subjected to a life away from his home town.
His married life will be full of happiness. He will be blessed to have a most suitable wife. His children also will be an asset, most obedient, understanding and respecting children. He will be blessed with grandchildren also. He is an ornament in his family.
Health:
His health will be very good. He is non-care about his own health. Hence he will search for a doctor only when he is seriously ill. He is prone to paralytic attack, stomach problems, piles, and hernia.
Female Natives:
Women born in this Nakshatra will also enjoy more or less the same results as that is applicable for male natives mentioned above. In addition, the following results will also be enjoyed:
Physical features:
She is of medium height with stout body. Large and protruding eyes.
Character and general events:
She is a real "Lakshmi" (goddess of wealth) in the family. She is the embodiment of a real family woman. Her behavior is extremely cordial, respectful and praise worthy. Adaptability as the circumstances warrants. Suitability as the occasion warrants and lastly impartiality as the country needs are her main characteristics. When all these three essentials required for the present day are combined in one, what more I can describe or attribute to her character.
.
Education, sources of earning / profession:
Employed females can attain good positions due to their own effort. She is best suited to the profession of a lawyer or arbitrator. She is also a good nurse or a doctor.
Family life:
These women will be a gem in any family they are born or married. In other words, their foot-steps are sufficient to bring in Laxmi (goddess of wealth). .
Health:
She is prone to rheumatic pains, acute indigestion, constipation, hernia and in some cases tuberculosis of low intensity.
Choosing Baby names for birth star Uthrattathi:
Those having Lagna or Lagna Lord in Uthrattathi, name should start with the following Syllable Thu, Gya, Sha, Shre
Traditional Hindu given names are determined by which pada (quarter) of a nakshatra the Lagna or Lagna Lord was in at the time of birth. The given name would begin with the following syllables:
Du (Devanagari: दु)
Jha (Devanagari: ज)
Tha (Devanagari: थ)
Da/Tra (Devanagari: ञ)
References
Nakshatra | Uttara Bhādrapadā | [
"Astronomy"
] | 1,129 | [
"Nakshatra",
"Constellations"
] |
8,868,378 | https://en.wikipedia.org/wiki/Axenic | In biology, axenic (, ) describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellular eukaryotes, but axenic cultures of many multicellular organisms are also possible. Axenic culture is an important tool for the study of symbiotic and parasitic organisms in a controlled environment.
Preparation
Axenic cultures of microorganisms are typically prepared by subculture of an existing mixed culture. This may involve use of a dilution series, in which a culture is successively diluted to the point where subsamples of it contain only a few individual organisms, ideally only a single individual (in the case of an asexual species). These subcultures are allowed to grow until the identity of their constituent organisms can be ascertained. Selection of those cultures consisting solely of the desired organism produces the axenic culture. Subculture selection may also involve manually sampling the target organism from an uncontaminated growth front in an otherwise mixed culture, and using this as an inoculum source for the subculture.
Axenic cultures are usually checked routinely to ensure that they remain axenic. One standard approach with microorganisms is to spread a sample of the culture onto an agar plate, and to incubate this for a fixed period of time. The agar should be an enriched medium that will support the growth of common "contaminating" organisms. Such "contaminating" organisms will grow on the plate during this period, identifying cultures that are no longer axenic.
Experimental use
As axenic cultures are derived from very few organisms, or even a single individual, they are useful because the organisms present within them share a relatively narrow gene pool. In the case of an asexual species derived from a single individual, the resulting culture should consist of identical organisms (though processes such as mutation and horizontal gene transfer may introduce a degree of variability). Consequently, they will generally respond in a more uniform and reproducible fashion, simplifying the interpretation of experiments.
Problems
The axenic culture of some pathogens is complicated because they normally thrive within host tissues which exhibit properties that are difficult to replicate in vitro. This is especially true in the case of intracellular pathogens. However, careful replication of key features of the host environment can resolve these difficulties (e.g. host metabolites, dissolved oxygen), such as with the Q fever pathogen, Coxiella burnetii.
See also
Asepsis
Gnotobiotic animal
Germ-free animal
Sterilization (microbiology)
References
Bacteria
Bacteriology
Biotechnology
Cell biology
Cell culture
Microbiology techniques
Microbiology terms | Axenic | [
"Chemistry",
"Biology"
] | 566 | [
"Cell biology",
"Prokaryotes",
"Biotechnology",
"Model organisms",
"Microbiology techniques",
"Bacteria",
"nan",
"Microbiology terms",
"Cell culture",
"Microorganisms"
] |
8,868,773 | https://en.wikipedia.org/wiki/Authenticated%20Identity%20Body | Authenticated Identity Body or AIB is a method allowing parties in a network to share authenticated identity, thereby increasing the integrity of their SIP communications. AIBs extend other authentication methods like S/MIME to provide a more specific mechanism to introduce integrity to SIP transmissions. Parties transmitting AIBs cryptographically sign a subset of SIP message headers, and such signatures assert the message originator's identity. To meet requirements of reference integrity (for example in defending against replay attacks) additional SIP message headers such as 'Date' and 'Contact' may be optionally included in the AIB.
AIB is described and discussed in RFC 3893: "For reasons of end-to-end privacy, it may also be desirable to encrypt AIBs [...]. While encryption of AIBs entails that only the holder of a specific key can decrypt the body, that single key could be distributed throughout a network of hosts that exist under common policies. The security of the AIB is therefore predicated on the secure distribution of the key. However, for some networks (in which there are federations of trusted hosts under a common policy), the widespread distribution of a decryption key could be appropriate. Some telephone networks, for example, might require this model. When an AIB is encrypted, the AIB should be encrypted before it is signed... Unless, of course, it is signed by Mrs. L in Rin, VA."
See also
References
Computer networks engineering
Cryptographic software
VoIP protocols
VoIP software | Authenticated Identity Body | [
"Mathematics",
"Technology",
"Engineering"
] | 327 | [
"Computer engineering",
"Computer network stubs",
"Computer networks engineering",
"Cryptographic software",
"Computing stubs",
"Mathematical software"
] |
8,868,861 | https://en.wikipedia.org/wiki/Trimesic%20acid | Trimesic acid, also known as benzene-1,3,5-tricarboxylic acid, is an organic compound with the formula C6H3(CO2H)3. It is one of three isomers of benzenetricarboxylic acid. A colorless solid, trimesic acid has some commercial value as a precursor to some plasticizers.
Trimesic acid can be combined with para-hydroxypyridine to make a water-based gel, stable up to 95 °C.
Trimesic acid crystallizes from water to form a hydrogen-bonded hydrated network with wide unidimensional empty channels.
See also
Trimellitic acid (1,2,4-benzenetricarboxylic acid)
Hemimellitic acid (1,2,3-benzenetricarboxylic acid)
References
Benzoic acids
Tricarboxylic acids
Carboxylic acid-based porous polymer monomers | Trimesic acid | [
"Chemistry"
] | 205 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
8,869,727 | https://en.wikipedia.org/wiki/Fixed-point%20property | A mathematical object X has the fixed-point property if every suitably well-behaved mapping from X to itself has a fixed point. The term is most commonly used to describe topological spaces on which every continuous mapping has a fixed point. But another use is in order theory, where a partially ordered set P is said to have the fixed point property if every increasing function on P has a fixed point.
Definition
Let A be an object in the concrete category C. Then A has the fixed-point property if every morphism (i.e., every function) has a fixed point.
The most common usage is when C = Top is the category of topological spaces. Then a topological space X has the fixed-point property if every continuous map has a fixed point.
Examples
Singletons
In the category of sets, the objects with the fixed-point property are precisely the singletons.
The closed interval
The closed interval [0,1] has the fixed point property: Let f: [0,1] → [0,1] be a continuous mapping. If f(0) = 0 or f(1) = 1, then our mapping has a fixed point at 0 or 1. If not, then f(0) > 0 and f(1) − 1 < 0. Thus the function g(x) = f(x) − x is a continuous real valued function which is positive at x = 0 and negative at x = 1. By the intermediate value theorem, there is some point x0 with g(x0) = 0, which is to say that f(x0) − x0 = 0, and so x0 is a fixed point.
The open interval does not have the fixed-point property. The mapping f(x) = x2 has no fixed point on the interval (0,1).
The closed disc
The closed interval is a special case of the closed disc, which in any finite dimension has the fixed-point property by the Brouwer fixed-point theorem.
Topology
A retract A of a space X with the fixed-point property also has the fixed-point property. This is because if is a retraction and is any continuous function, then the composition (where is inclusion) has a fixed point. That is, there is such that . Since we have that and therefore
A topological space has the fixed-point property if and only if its identity map is universal.
A product of spaces with the fixed-point property in general fails to have the fixed-point property even if one of the spaces is the closed real interval.
The FPP is a topological invariant, i.e. is preserved by any homeomorphism. The FPP is also preserved by any retraction.
According to the Brouwer fixed-point theorem, every compact and convex subset of a Euclidean space has the FPP. More generally, according to the Schauder-Tychonoff fixed point theorem every compact and convex subset of a locally convex topological vector space has the FPP. Compactness alone does not imply the FPP and convexity is not even a topological property so it makes sense to ask how to topologically characterize the FPP. In 1932 Borsuk asked whether compactness together with contractibility could be a sufficient condition for the FPP to hold. The problem was open for 20 years until the conjecture was disproved by Kinoshita who found an example of a compact contractible space without the FPP.
References
Fixed points (mathematics) | Fixed-point property | [
"Mathematics"
] | 719 | [
"Fixed points (mathematics)",
"Mathematical analysis",
"Topology",
"Dynamical systems"
] |
8,870,404 | https://en.wikipedia.org/wiki/An%20Experiment%20on%20a%20Bird%20in%20the%20Air%20Pump | An Experiment on a Bird in the Air Pump is a 1768 oil-on-canvas painting by Joseph Wright of Derby, one of a number of candlelit scenes that Wright painted during the 1760s. The painting departed from convention of the time by depicting a scientific subject in the reverential manner formerly reserved for scenes of historical or religious significance. Wright was intimately involved in depicting the Industrial Revolution and the scientific advances of the Enlightenment. While his paintings were recognised as exceptional by his contemporaries, his provincial status and choice of subjects meant the style was never widely imitated. The picture has been owned by the National Gallery in London since 1863 and is regarded as a masterpiece of British art.
The painting depicts a natural philosopher, a forerunner of the modern scientist, recreating one of Robert Boyle's air pump experiments, in which a bird is deprived of air, before a varied group of onlookers. The group exhibits a variety of reactions, but for most of the audience scientific curiosity overcomes concern for the bird. The central figure looks out of the picture as if inviting the viewer's participation in the outcome.
Historical background
In 1659, Robert Boyle commissioned the construction of an air pump, then described as a "pneumatic engine", which is known today as a "vacuum pump". The air pump was invented by Otto von Guericke in 1650, though its high cost deterred most contemporary scientists from constructing the apparatus. Boyle, the son of the Earl of Cork, had no such concerns—after its construction, he donated the initial 1659 model to the Royal Society and had a further two redesigned machines built for his personal use. Aside from Boyle's three pumps, there were probably no more than four others in existence during the 1660s: Christiaan Huygens had one in The Hague, Henry Power may have had one at Halifax, and there may have been pumps at Christ's College, Cambridge, and the Montmor Academy in Paris. Boyle's pump, which was largely designed to Boyle's specifications and constructed by Robert Hooke, was complicated, temperamental, and problematic to operate. Many demonstrations could only be performed with Hooke on hand, and Boyle frequently left critical public displays solely to Hooke—whose dramatic flair matched his technical skill.
Despite the operational and maintenance obstacles, construction of the pump enabled Boyle to conduct a great many experiments on the properties of air, which he later detailed in his New Experiments Physico-Mechanicall, Touching the Spring of the Air, and its Effects, (Made, for the Most Part, in a New Pneumatical Engine). In the book, he described in great detail 43 experiments he conducted, on occasion assisted by Hooke, on the effect of air on various phenomena. Boyle tested the effects of "rarified" air on combustion, magnetism, sound, and barometers, and examined the effects of increased air pressure on various substances. He listed two experiments on living creatures: "Experiment 40", which tested the ability of insects to fly under reduced air pressure, and the dramatic "Experiment 41," which demonstrated the reliance of living creatures on air for their survival. In this attempt to discover something "about the account upon which Respiration is so necessary to the Animals, that Nature hath furnish'd with Lungs", Boyle conducted numerous trials during which he placed a large variety of different creatures, including birds, mice, eels, snails and flies, in the vessel of the pump and studied their reactions as the air was removed. Here, he describes an injured lark:
By the time Wright painted his picture in 1768, air pumps were a relatively commonplace scientific instrument, and itinerant "lecturers in natural philosophy"—usually more showmen than scientists—often performed the "animal in the air pump experiment" as the centrepiece of their public demonstration. These were performed in town halls and other large buildings for a ticket-buying audience, or were booked by societies or for private showings in the homes of the well-off, the setting suggested in both of Wright's demonstration pieces. One of the most notable and respectable of the travelling lecturers was James Ferguson FRS, a Scottish astronomer and probable acquaintance of Joseph Wright (both were friends of John Whitehurst). Ferguson noted that a "lungs-glass" with a small air-filled bladder inside was often used in place of the animal, as using a living creature was "too shocking to every spectator who has the least degree of humanity".
The full moon in the picture is significant as meetings of the Lunar Circle (renamed the Lunar Society by 1775) were timed to make use of its light when travelling.
Wright met Erasmus Darwin in the early 1760s, probably through their common connection of John Whitehurst, first consulting Darwin about ill health in 1767 when he stayed in the Darwin household for a week. The energy and vivacity of both Erasmus and Mary (Polly) Darwin impressed Wright. In the 1980s Eric Evans (National Gallery) suggested that Darwin is the figure in the left foreground who holds a watch. As this composed timekeeper is not consistent with Darwin's flamboyant character, it is more likely that this is Dr William Small. The attention to timekeeping fits with Dr Small's role as the social secretary for the Lunar Circle. Small returned from Virginia in 1764 and established his practice in Birmingham in 1765, consistent with this being a meeting in 1767. The profile and wig of this figure are consistent with a contemporary portrait of Small by Tilly Kettle.
Painting
Background
During his apprenticeship and early career Wright concentrated on portraiture. By 1762, he was an accomplished portrait artist, and his 1764 group portrait James Shuttleworth, his Wife and Daughter is acknowledged as his first true masterpiece. Benedict Nicolson suggests that Wright was influenced by the work of Thomas Frye; in particular by the 18 bust-length mezzotints which Frye completed just before his death in 1762. It was perhaps Frye's candlelight images that tempted Wright to experiment with subject pieces. Wright's first attempt, A Girl reading a Letter by candlelight with a Young Man looking over her shoulder from 1762 or 1763, is a trial in the genre, and is fetching though uncomplicated.
Wright's An Experiment on a Bird in the Air Pump forms part of a series of candlelit nocturnes that he produced between 1765 and 1768.
There was a long history of painting candlelit scenes in Western art, although as Wright had not at this date travelled abroad, there remains uncertainty as to what paintings he might have seen in the original, as opposed to prints. Nicolson, who made studies of both Wright and other candlelight painters such as the 17th-century Utrecht Caravaggisti, thought their paintings, among the largest in the style, those most likely to have influenced Wright. However Judy Egerton wonders if he could have seen any, preferring as influences the far smaller works of the Leiden fijnschilder Godfried Schalcken (1643–1706), whose reputation was much greater in the early 18th century than subsequently. He had worked in England from 1692 to 1697, and several of his paintings can be placed in English collections in Wright's day.
Although he was the leading expert writing in English, Nicolson does not suggest that Wright is likely to have known of the 17th-century candlelit narrative religious subjects of Georges de La Tour and Trophime Bigot, which, in their seriousness, are the closest works to Wright that are lit only by candle. The Dutch painters' works and other candlelit scenes by 18th-century English painters such as Henry Morland (father of George) tended instead to exploit the possibilities of semi-darkness for erotic suggestiveness. Some of Wright's own later candlelit scenes were by no means as serious as his first ones, as seen from their titles: Two Boys Fighting Over a Bladder and Two Girls Dressing a Kitten by Candlelight.
The first of his candlelit masterpieces, Three Persons Viewing the Gladiator by Candlelight, was painted in 1765, and showed three men studying a small copy of the "Borghese Gladiator". Viewing the Gladiator was greatly admired; but his next painting, A Philosopher giving that Lecture on the Orrery, in which a Lamp is put in place of the Sun (normally known by the shortened form A Philosopher Giving a Lecture on the Orrery or just The Orrery), caused a greater stir, as it replaced the Classical subject at the centre of the scene with one of a scientific nature. Wright's depiction of the awe produced by scientific "miracles" marked a break with traditions in which the artistic depiction of such wonder was reserved for religious events, since to Wright the marvels of the technological age were as awe-inspiring as the subjects of the great religious paintings.
In both of these works the candlelit setting had a realist justification. Viewing sculpture by candlelight, when the contours showed well and there might even be an impression of movement from the flickering light, was a fashionable practice described by Goethe. In the orrery demonstration the shadows cast by the lamp representing the sun were an essential part of the display, used to demonstrate eclipses. But there seems no reason other than heightened drama to stage the air pump experiment in a room lit by a single candle, and in two later paintings of the subject by Charles-Amédée-Philippe van Loo the lighting is normal.
The painting was one of a number of British works challenging the set categories of the rigid, French-dictated hierarchy of genres in the late 18th century, as other types of painting aspired to be treated as seriously as the costumed history painting of a Classical or mythological subject. In some respects the Orrery and Air Pump subjects resembled conversation pieces, then largely a form of middle-class portraiture, though soon to be given new status when Johann Zoffany began to paint the royal family in about 1766. Given their solemn atmosphere however, and as it seems none of the figures are intended to be understood as portraits (even if models may be identified), the paintings can not be regarded as conversation pieces. The 20th-century art historian Ellis Waterhouse compares these two works to the "genre serieux" of contemporary French drama, as defined by Denis Diderot and Pierre Beaumarchais, a view endorsed by Egerton.
An anonymous review from the time called Wright "a very great and uncommon genius in a peculiar way". The Orrery was painted without a commission, probably in the expectation that it would be bought by Washington Shirley, 5th Earl Ferrers, an amateur astronomer who had an orrery of his own, and with whom Wright's friend Peter Perez Burdett was staying while in Derbyshire. Figures thought to be portraits of Burdett and Ferrers feature in the painting, Burdett taking notes and Ferrers seated with his son next to the orrery.
Ferrers purchased the painting for £210, but the 6th Earl auctioned it off, and it is now held by Derby Museum and Art Gallery.
Detail
An Experiment on a Bird in the Air Pump followed in 1768, the emotionally charged experiment contrasting with the orderly scene from The Orrery. The painting, which measures 72 by 94½ inches (183 by 244 cm), shows a grey cockatiel fluttering in panic as the air is slowly withdrawn from the vessel by the pump. The witnesses display various emotions: one of the girls worriedly watches the fate of the bird, while the other is too upset to observe and is comforted by her father; two gentlemen (one of them dispassionately timing the experiment) and a boy look on with interest, while the young lovers to the left of the painting are absorbed only in each other. The scientist himself looks directly out of the picture, as if challenging the viewer to judge whether the pumping should continue, killing the bird, or whether the air should be replaced and the cockatiel saved.
Aside from that of the children, little sympathy is directed toward the bird; David Solkin suggests the subjects of the painting show the dispassionate detachment of the evolving scientific society. Individuals are concerned for each other: the father for his children, the young man for the girl, but the distress of the cockatiel elicits only careful study. To one side of the boy at the rear, the cockatiel's empty cage can be seen on the wall, and to further heighten the drama it is unclear whether the boy is lowering the cage on the pulley to allow the bird to be replaced after the experiment or hoisting the cage back up, certain of its former occupant's death. It has also been suggested that he may be drawing the curtains to block out the light from the full moon.
Jenny Uglow believes that the boy echoes the figure in the last print of William Hogarth's The Four Stages of Cruelty by pointing out the arrogance and potential cruelty of experimentation, while David Fraser also sees the compositional similarities with the audience grouped round a central demonstration. The neutral stance of the central character and the uncertain intentions of the boy with the cage were both later ideas: an early study, discovered on the back of a self-portrait, omits the boy and shows the natural philosopher reassuring the girls. In this sketch it is obvious that the bird will survive, and thus the composition lacks the power of the final version. Lochlann Jain has analysed the painting in the context of a contemporary cultural history and medicine of human suffocation and choking.
Wright, who took many of his subjects from English poetry, probably knew the following passage from "The Wanderer" (1729) by Richard Savage:
So in some Engine, that denies a Vent,
If unrespiring is some Creature pent,
It sickens, droops, and pants, and gasps for Breath,
Sad o'er the Sight swim shad'wy Mists of Death;
If then kind Air pours powerful in again.
New Heats, new Pulses quicken ev'ry Vein;
From the clear'd, lifted, life-rekindled Eye,
Dispers'd, the dark and dampy Vapours fly.
The cockatiel would have been a rare bird at the time, "and one whose life would never in reality have been risked in an experiment such as this". It did not become well known until after it was shown in illustrations to the accounts of the voyages of Captain Cook in the 1770s. Prior to Cook's voyage, cockatiels had been imported only in small numbers as exotic cage-birds. Wright had painted one in 1762 at the home of William Chase, featuring it both in his portrait of Chase and his wife (Mr & Mrs William Chase) and a separate study, The Parrot. In selecting such a rarity for this scientific sacrifice, Wright not only chose a more dramatic subject than the "lungs-glass", but was perhaps making a statement about the values of society in the Age of Enlightenment. The grey plumage of the cockatiel also shows much more effectively in the darkened room than the small dull-coloured bird in Wright's early oil sketch. A resemblance has been pointed out between the group of the bird and the two nearest figures and a type of depiction of the Trinity found in Early Netherlandish painting, where the Holy Spirit is represented by a dove, to which God the Father (the philosopher) points, while Christ (the father) gestures in blessing to the viewer.
On the table are various other pieces of equipment that the natural philosopher would have used during his demonstration: a thermometer, candle snuffer and cork, and close to the man seated to the right is a pair of Magdeburg hemispheres, which would have been used with the air pump to demonstrate the difference in pressure exerted by the air and a vacuum: when the air was pumped out from between the two hemispheres they were impossible to pull apart. The air pump itself is rendered in exquisite detail, a faithful record of the designs in use at the time. What may be a human skull in the large liquid-filled glass bowl would not have been a normal piece of equipment; William Schupbach suggests that it and the candle, which is presumably lighting the bowl from behind, form a vanitas—the two symbols of mortality reflecting the cockatiel's struggle for life.
Style
The powerful central light source creates a chiaroscuro effect. The light illuminating the scene has been described as "so brilliant it could only be the light of revelation". The single source of light is obscured behind the bowl on the table; some hint of a lamp glass can be seen around the side of the bowl, but David Hockney has suggested that the bowl itself may contain sulphur, giving a powerful single light source that a candle or oil lamp would not. In the earlier study a candle holder is visible, and the flame is reflected in the bowl. Hockney believes that many of the Old Masters used optical equipment to assist in their painting, and suggests that Wright may have used lenses to transfer the image to paper rather than painting directly from the scene, as he believes the pattern of shadows thrown by the lighting could have been too complicated for Wright to have captured so accurately without assistance. It may be observed, however, that the stand on which the pump is situated casts no shadow on the body of the philosopher, as it could be expected to do.
Wright's Air Pump was unusual in that it depicted archetypes rather than specific people, though various models for the figures have been suggested. The young lovers may have been based on Thomas Coltman and Mary Barlow, friends of Wright's, whom he later painted in Mr and Mrs Thomas Coltman (also in the National Gallery) after their marriage in 1769; Erasmus Darwin has been suggested as the man timing the experiment on the left of the table, and John Warltire, whom Darwin had invited to help with some air pump experiments in real life, as the natural philosopher; but Wright never identified any of the subjects or suggested they were based on real people.
In The Orrery, all the subjects have been identified apart from the philosopher, who has physical similarities to Isaac Newton but differs enough to make positive identification impossible. Nicolson detects the strong influence of Frye throughout the picture. Particularly striking is the similarity between Frye's mezzotint Portrait of a Young Man of 1760–1761 and the figure of the boy with his head cocked staring intently at the bird. In 1977, Michael Wynne published one of Frye's chalk drawings from around 1760, An old man leaning on a staff, which is so similar to the observer in the right foreground in Wright's picture to make it impossible that Wright had not seen it. There are other hints of Frye's style in the painting: even the figure of the natural philosopher has touches of Frye's Figure with Candle. Though Henry Fuseli would later also develop on the style of Frye's work there is no evidence of him having painted anything similar until the early 1780s. So, although he had already been in England at the time the Air Pump was produced, it is unlikely that he was an influence on Wright.
Wright's scientific paintings adopted elements from the tradition of history painting but lacked the heroic central action typical of that genre. While ground-breaking, they are regarded as peculiar to Wright, whose unique style has been explained in many ways. Wright's provincial status and ties to the Lunar Society, a group of prominent industrialists, scientists and intellectuals who met regularly in Birmingham between 1765 and 1813, have been highlighted, as well as his close association with and sympathy for the advances made in the burgeoning Industrial Revolution. Other critics have emphasised a desire to capture a snapshot of the society of the day, in the tradition of William Hogarth but with a more neutral stance that lacks the biting satire of Hogarth's work.
Reception
The scientific subjects of Wright's paintings from this time were meant to appeal to the wealthy scientific circles in which he moved. While never a member himself, he had strong connections with the Lunar Society: he was friends with members John Whitehurst and Erasmus Darwin, as well as Josiah Wedgwood, who later commissioned paintings from him. The inclusion of the moon in the painting was a nod to their monthly meetings, which were held when the moon was full. Like The Orrery, Wright apparently painted Air Pump without a commission, and the picture was purchased by Dr Benjamin Bates, who already owned Wright's Gladiator. An Aylesbury physician, patron of the arts and hedonist, Bates was a diehard member of the Hellfire Club. Wright's account book shows a number of prices for the painting: Pd£200 is shown in one place and £210 in another, but Wright had written to Bates asking for £130, stating that the low price "might much injure me in the future sale of my pictures, and when I send you a receipt for the money I shall acknowledge a greater sum." Whether Bates ever paid the full amount is not recorded; Wright only notes in his account book that he received £30 in part payment.
Wright exhibited the painting at the Society of Artists exhibition in 1768 and it was re-exhibited before Christian VII of Denmark in September the same year. Viewers remarked that it was "clever and vigorous", while Gustave Flaubert, who saw it on a visit to England in 1865–66, considered it "charmant de naïveté et profondeur". It was popular enough that a mezzotint was engraved from it by Valentine Green which was published by John Boydell on 24 June 1769, and initially sold for 15 shillings. This was reprinted throughout the 18th and 19th centuries, in increasingly weak impressions. Ellis Waterhouse called it "one of the wholly original masterpieces of British art".
From Bates, the picture passed to Walter Tyrell; another member of the Tyrell family, Edward, presented it to the National Gallery, London, in 1863, after it had failed to sell at an auction at Christie's in 1854. The painting was transferred to the Tate Gallery in 1929, although it was actually on loan to Derby Museum and Art Gallery between 1912 and 1947. It has been lent out for exhibitions to the National Gallery of Art in Washington, D.C., in 1976, the National Museum of Fine Arts in Stockholm in 1979–1980, and Paris (Grand Palais), New York (Metropolitan) and the Tate in London in 1990. It was reclaimed by the National Gallery from the Tate in 1986. They describe its condition as good, with minor alterations visible on some figures. It was last cleaned in 1974.
The striking scene has been used as the cover illustration for many books on topics both artistic and scientific. It has even spawned pastiches and parodies: the book cover of The Science of Discworld, by Terry Pratchett, Ian Stewart and Jack Cohen, is a tribute to the painting by artist Paul Kidby, who replaces Wright's figures with the book's protagonists. Shelagh Stephenson's play An Experiment with an Air Pump, inspired by the painting, was the joint winner of the 1997 Margaret Ramsay Award and had its premiere at the Royal Exchange Theatre, Manchester, in 1998.
Notes
References
Egerton, Judy (1998), National Gallery Catalogues (new series): The British School. catalogue entry pp. 332–343,
Guilding, Ruth, and others, William Weddell and the transformation of Newby Hall, Jeremy Mills Publishing for Leeds Museums and Galleries, 2004, , Google books
Waterhouse, Ellis, (4th Edn, 1978) Painting in Britain, 1530–1790. Penguin Books (now Yale History of Art series),
External links
Zoomable version of the painting from the National Gallery, London
An interactive soundscape of the painting
1768 paintings
Science in art
Physics experiments
Paintings by Joseph Wright of Derby
Historical scientific instruments
Paintings in the National Gallery, London
Parrots in art
Robert Boyle | An Experiment on a Bird in the Air Pump | [
"Physics"
] | 4,933 | [
"Experimental physics",
"Physics experiments"
] |
8,870,608 | https://en.wikipedia.org/wiki/Swastika%20Stone | The Swastika Stone is a stone adorned with a design that resembles a swastika, located on the Woodhouse Crag on the northern edge of Ilkley Moor in West Yorkshire, England. The design has a double outline with four curved arms and an attached S-shape, each enclosing a so-called 'cup' mark, the like of which can be found on other stones nearby.
The stone is not verifiably dated; however the academic consensus suggests it to have been carved sometime around the Neolithic or early Bronze Age.
Alternative views have claimed the design is rare in the British Isles, so its close similarity to Camunian rose designs in Lombardy/Italy have led some to theorise that the two are connected. In fact, the troops stationed in Ilkley during Roman occupation were recruited from the Celtic Lingones. This tribe was native to Gaul, but in around 400 BC, some migrated across the Alps to the Adriatic coast. Some believe the Ilkley Lingones were recruited from here rather than from Gaul. It is possible that the Italian Lingones passed through the Valcamonica region at some point, took on the swastika designs they found as part of their tribal symbolism, and carved it on the nearby moor when stationed in Ilkley.
See also
Camunian rose
Fylfot
Germanic pre-Christian use of the swastika
Lauburu
Western use of the swastika in the early 20th century
References
External links
The Swastika Stone
Prehistoric Britain
Archaeological sites in West Yorkshire
Swastika
Petroglyphs
Ilkley
Stones | Swastika Stone | [
"Physics"
] | 320 | [
"Stones",
"Physical objects",
"Matter"
] |
8,870,657 | https://en.wikipedia.org/wiki/Wat%27s%20Dyke | Wat's Dyke () is a linear earthwork running through the northern Welsh Marches from Basingwerk Abbey on the River Dee estuary, passing east of Oswestry and on to Maesbury in Shropshire, England. It runs generally parallel to Offa's Dyke, sometimes within a few yards but never more than away. It now appears insignificant and is visible in some places as a raised hedgerow and in others no more than a cropmark. The ditch has long since been filled in and the bank ploughed away, but originally it was a considerable construction, considered to be strategically more sophisticated than Offa's Dyke. The date of construction is disputed, ranging from sub-Roman to the early ninth century.
Construction and siting
It consists of the usual bank and ditch of an ancient dyke, with the ditch on the western side, meaning that the dyke faces Wales and by implication can be seen as protecting the English lands to the east. The placement of the dyke in the terrain also shows that care was taken to provide clear views to the west and to use local features to the best defensive advantage.
A section of the dyke extends north and south from Old Oswestry, an Iron Age hill fort.
Dating controversy
The dyke was previously thought to date to the early 8th century, constructed by Æthelbald, king of Mercia, who reigned from 716 to 757. Æthelbald's successor, Offa, built the dyke which carries his name at some point during his reign (757 to 796).
Excavations in the 1990s at Maes-y-Clawdd near Oswestry uncovered the remains of a small fire site together with eroded shards of Romano-British pottery and quantities of charcoal, which have been dated to between 411 and 561 AD (centered around 446 AD). This evidence would seem to place the building of the dyke in the era of the post-Roman kingdom whose capital was at Wroxeter (just south of modern-day Shrewsbury) about to the east.
The dating of the fire site and hence the dyke has been disputed, and it has been suggested that owing to the difficulties inherent in radiocarbon dating, this single date cannot be fully trusted and also that the dyke could easily have been built on top of the fire site at a later date.
Excavations in 2006 suggested a much later date of 792–852, and the earlier date is now thought to relate to a fire site of a sub-Roman earthwork which preceded the actual dyke. It has been tentatively suggested that the likely context for construction is in the 820s, when the Mercian king Coenwulf was fighting against a resurgent Welsh threat.
Wat's Dyke Way
The approximate line of the earthwork is followed by the Wat's Dyke Way, a waymarked long-distance path running for from Llanymynech in Powys to Basingwerk Abbey on the River Dee near Holywell. It was opened in 2007.
See also
Wansdyke, a similar earthwork created during sub-Roman decades in Wiltshire and Somerset
Scots' Dike, a linear earthwork constructed in 1552 to mark the division of the Debatable Lands and thereby settle the exact boundary between the Kingdoms of Scotland and England, on the Anglo-Scottish border
Black Pig's Dyke in Ireland
Broadclough Dykes in Lancashire
References
Further reading
Blake, Steve and Scott, Lloyd (2003): The Keys to Avalon: The True Location of Arthur’s Kingdom Revealed. Revised Edition, published by Rider.
Hannaford, H. R. (1998): "Archaeological Excavations on Wat’s Dyke at Maes-y-Clawdd," Archaeology Service, Shropshire County Council, report no. 132, December 1997.
Worthington, Margaret (1997): '"Wat’s Dyke: An Archaeological and Historical Enigma," Bulletin John Rylands Library, Manchester, Vol 79, no. 3, 1997. Reprinted in Offa's Dyke Journal, vol. 1, 2019, pp. 58–79
External links
www.geograph.co.uk – photos of Wat's Dyke today
Anglo-Saxon sites in England
Anglo-Saxon sites in Wales
Archaeological sites in Powys
Fortifications in England
Fortifications in Wales
History of Shropshire
Archaeological sites in Shropshire
England–Wales border
Ancient dikes
Fortification lines
Scheduled monuments in Flintshire
Linear earthworks | Wat's Dyke | [
"Engineering"
] | 889 | [
"Fortification lines"
] |
8,871,506 | https://en.wikipedia.org/wiki/Buformin | Buformin (1-butylbiguanide) is an oral antidiabetic drug of the biguanide class, chemically related to metformin and phenformin. Buformin was marketed by German pharmaceutical company Grünenthal as Silubin.
Chemistry and animal toxicology
Buformin hydrochloride is a fine, white to slightly yellow, crystalline, odorless powder, with a weakly acidic bitter taste. Its melting point is 174 to 177 °C, it is a strong base, and is freely soluble in water, methanol and ethanol, but insoluble in chloroform and ether. Toxicity: guinea pig LD50 subcutaneous 18 mg/kg; mouse LD50 intraperitoneal 140 mg/kg and 300 mg/kg oral. The log octanol-water partition coefficient (log P) is -1.20E+00; its water solubility is 7.46E+05 mg/L at 25 °C. Vapor pressure is 1.64E-04 mm Hg at 25 °C (EST); Henry's law constant is 8.14E-16 atm-m3/mole at 25 °C (EST). Its Atmospheric -OH rate constant is 1.60E-10 cm3/molecule-sec at 25 °C.
Mechanism of action
Buformin delays absorption of glucose from the gastrointestinal tract, increases insulin sensitivity and glucose uptake into cells, and inhibits synthesis of glucose by the liver. Buformin and the other biguanides are not hypoglycemic, but rather antihyperglycemic agents. They do not produce hypoglycemia; instead, they reduce basal and postprandial hyperglycemia in diabetics. Biguanides may antagonize the action of glucagon, thus reducing fasting glucose levels.
Pharmacokinetics
After oral administration of 50 mg of buformin to volunteers, almost 90% of the applied quantity was recovered in the urine; the rate constant of elimination was found to be 0.38 per hr. Buformin is a strong base (pKa = 11.3) and not absorbed in the stomach. After intravenous injection of about 1 mg/kg buformin-14-C, the initial serum concentration is 0.2-0.4 μg/mL. Serum level and urinary elimination rate are linearly correlated. In man, after oral administration of 50 mg 14-C-buformin, the maximum serum concentration was 0.26-0.41 μg/mL. The buformin was eliminated with an average half-life of 2 h. About 84% of the dose administered was found excreted unchanged in the urine. Buformin is not metabolized in humans. The bioavailability of oral buformin and other biguanides is 40%-60%. Binding to plasma proteins is absent or very low.
Dosage
The daily dose of buformin is 150–300 mg by mouth. Buformin has also been available in a sustained release preparation, Silubin Retard, which is still sold in Romania.
Side effects and contraindications
The side effects encountered are anorexia, nausea, diarrhea, metallic taste, and weight loss. Its use is contraindicated in
diabetic coma, ketoacidosis, severe infection, trauma, other conditions where buformin is unlikely to control the hyperglycemia, renal or hepatic impairment, heart failure, recent myocardial infarct, dehydration, alcoholism, and conditions likely to predispose to lactic acidosis.
Toxicity
Buformin was withdrawn from the market in many countries due to an elevated risk of causing lactic acidosis (although not the US, where it was never sold). Buformin is still available and prescribed in Romania (timed release Silubin Retard is sold by Zentiva), Hungary, Taiwan and Japan (sold by Nichi-Iko Pharmaceutical Co., Ltd as "DIBETOS" tablets, each containing 50 mg buformin hydrochloride). The lactic acidosis occurred only in patients with a buformin plasma level of greater than 0.60 μg/mL and was rare in patients with normal renal function.
In one report, the toxic oral dose was 329 ± 30 mg/day in 24 patients who developed lactic acidosis on buformin. Another group of 24 patients on 258 ± 25 mg/day did not develop lactic acidosis on buformin.
Anticancer properties
Buformin, along with phenformin and metformin, inhibits the growth and development of cancer. The anticancer property of these drugs is due to their ability to disrupt the Warburg effect and revert the cytosolic glycolysis characteristic of cancer cells to normal oxidation of pyruvate by the mitochondria. Metformin reduces liver glucose production in diabetics and disrupts the Warburg effect in cancer by AMPK activation and inhibition of the mTor pathway. Buformin decreased cancer incidence, multiplicity, and burden in chemically induced rat mammary cancer, whereas metformin and phenformin had no statistically significant effect on the carcinogenic process relative to the control group. Buformin also exhibits anti-proliferative and anti-invasive effects in endometrial cancer cells, lung cancer cells and cervical cancer cells.
Antiviral properties
Biguanides were first noted to be active against influenza in the 1940s. Further studies confirmed their antiviral activity in vitro. Buformin, especially, was potently antiviral against vaccinia and influenza. Buformin is a metabolic antiviral that inhibits the mTOR pathway used by influenza and Middle East respiratory syndrome-related coronavirus.
History
Buformin was synthesized as an oral antidiabetic in 1957.
Synthesis
Buformin is obtained by reaction of butylamine and 2-cyanoguanidine.
References
Withdrawn drugs
Biguanides
Butyl compounds | Buformin | [
"Chemistry"
] | 1,278 | [
"Drug safety",
"Withdrawn drugs"
] |
8,871,770 | https://en.wikipedia.org/wiki/Membrane%20fluidity | In biology, membrane fluidity refers to the viscosity of the lipid bilayer of a cell membrane or a synthetic lipid membrane. Lipid packing can influence the fluidity of the membrane. Viscosity of the membrane can affect the rotation and diffusion of proteins and other bio-molecules within the membrane, there-by affecting the functions of these things.
Membrane fluidity is affected by fatty acids. More specifically, whether the fatty acids are saturated or unsaturated has an effect on membrane fluidity. Saturated fatty acids have no double bonds in the hydrocarbon chain, and the maximum amount of hydrogen. The absence of double bonds decreases fluidity. Unsaturated fatty acids have at least one double bond, creating a "kink" in the chain. The double bond increases fluidity. While the addition of one double bond raises the melting temperature, research conducted by Xiaoguang Yang et. al. supports that four or more double bonds has a direct correlation to membrane fluidity. Membrane fluidity is also affected by cholesterol. Cholesterol can make the cell membrane fluid as well as rigid.
Factors determining membrane fluidity
Membrane fluidity can be affected by a number of factors. The main factors affecting membrane fluidity are environmental (ie. temperature), and compositionally. One way to increase membrane fluidity is to heat up the membrane. Lipids acquire thermal energy when they are heated up; energetic lipids move around more, arranging and rearranging randomly, making the membrane more fluid. At low temperatures, the lipids are laterally ordered and organized in the membrane, and the lipid chains are mostly in the all-trans configuration and pack well together.
The melting temperature of a membrane is defined as the temperature across which the membrane transitions from a crystal-like to a fluid-like organization, or vice versa. This phase transition is not an actual state transition, but the two levels of organizations are very similar to a solid and liquid state.
: The membrane is in the crystalline phase, the level of order in the bi-layer is high and the fluidity is low.
: The membrane is in the liquid-crystal phase, the membrane is less ordered and more fluid. At 37 °C, this is the state of the membrane: the presence of cholesterol, though, allows for the membrane stabilization and a more compact organization.
The composition of a membrane can also affect its fluidity. The membrane phospholipids incorporate fatty acyl chains of varying length and saturation. Lipids with shorter chains are less stiff and less viscous because they are more susceptible to changes in kinetic energy due to their smaller molecular size and they have less surface area to undergo stabilizing London forces with neighboring hydrophobic chains. Molecules with carbon-carbon double bonds (unsaturated) are more rigid than those that are saturated with hydrogens, as double bonds cannot freely turn. As a result, the presence of fatty acyl chains with unsaturated double bonds makes it harder for the lipids to pack together by putting kinks into the otherwise straightened hydrocarbon chain. While unsaturated lipids may have more rigid individual bonds, membranes made with such lipids are more fluid because the individual lipids cannot pack as tightly as saturated lipids and thus have lower melting points: less thermal energy is required to achieve the same level of fluidity as membranes made with lipids with saturated hydrocarbon chains. Incorporation of particular lipids, such as sphingomyelin, into synthetic lipid membranes is known to stiffen a membrane. Such membranes can be described as "a glass state, i.e., rigid but without crystalline order".
Cholesterol acts as a bidirectional regulator of membrane fluidity because at high temperatures, it stabilizes the membrane and raises its melting point, whereas at low temperatures it intercalates between the phospholipids and prevents them from clustering together and stiffening. Some drugs, e.g. Losartan, are also known to alter membrane viscosity. Another way to change membrane fluidity is to change the pressure. In the laboratory, supported lipid bilayers and monolayers can be made artificially. In such cases, one can still speak of membrane fluidity. These membranes are supported by a flat surface, e.g. the bottom of a box. The fluidity of these membranes can be controlled by the lateral pressure applied, e.g. by the side walls of a box.
Heterogeneity in membrane physical property
Discrete lipid domains with differing composition, and thus membrane fluidity, can coexist in model lipid membranes; this can be observed using fluorescence microscopy. The biological analogue, 'lipid raft', is hypothesized to exist in cell membranes and perform biological functions. Also, a narrow annular lipid shell of membrane lipids in contact with integral membrane proteins have low fluidity compared to bulk lipids in biological membranes, as these lipid molecules stay stuck to surface of the protein macromolecules.
Measurement methods
Membrane fluidity can be measured with electron spin resonance, fluorescence, atomic force microscopy-based force spectroscopy, or deuterium nuclear magnetic resonance spectroscopy. Electron spin resonance measurements involve observing spin probe behaviour in the membrane. Fluorescence experiments involve observing fluorescent probes incorporated into the membrane. Atomic force microscopy experiments can measure fluidity on synthetic or isolated patches of native membranes. Solid state deuterium nuclear magnetic resonance spectroscopy involves observing deuterated lipids. The techniques are complementary in that they operate on different timescales.
Membrane fluidity can be described by two different types of motion: rotational and lateral. In electron spin resonance, rotational correlation time of spin probes is used to characterize how much restriction is imposed on the probe by the membrane. In fluorescence, steady-state anisotropy of the probe can be used, in addition to the rotation correlation time of the fluorescent probe. Fluorescent probes show varying degree of preference for being in an environment of restricted motion. In heterogeneous membranes, some probes will only be found in regions of higher membrane fluidity, while others are only found in regions of lower membrane fluidity. Partitioning preference of probes can also be a gauge of membrane fluidity. In deuterium nuclear magnetic resonance spectroscopy, the average carbon-deuterium bond orientation of the deuterated lipid gives rise to specific spectroscopic features. All three of techniques can give some measure of the time-averaged orientation of the relevant (probe) molecule, which is indicative of the rotational dynamics of the molecule.
Lateral motion of molecules within the membrane can be measured by a number of fluorescence techniques: fluorescence recovery after photobleaching involves photobleaching a uniformly labelled membrane with an intense laser beam and measuring how long it takes for fluorescent probes to diffuse back into the photobleached spot. Fluorescence correlation spectroscopy monitors the fluctuations in fluorescence intensity measured from a small number of probes in a small space. These fluctuations are affected by the mode of lateral diffusion of the probe. Single particle tracking involves following the trajectory of fluorescent molecules or gold particles attached to a biomolecule and applying statistical analysis to extract information about the lateral diffusion of the tracked particle.
Phospholipid-deficient bio-membranes
A study of central linewidths of electron spin resonance spectra of thylakoid membranes and aqueous dispersions of their total extracted lipids, labeled with stearic acid spin label (having spin or doxyl moiety at 5,7,9,12,13,14 and 16th carbons, with reference to carbonyl group), reveals a fluidity gradient. Decreasing linewidth from 5th to 16th carbons represents increasing degree of motional freedom (fluidity gradient) from headgroup-side to methyl terminal in both native membranes and their aqueous lipid extract (a multilamellar liposomal structure, typical of lipid bilayer organization). This pattern points at similarity of lipid bilayer organization in both native membranes and liposomes. This observation is critical, as thylakoid membranes comprising largely galactolipids, contain only 10% phospholipid, unlike other biological membranes consisting largely of phospholipids. Proteins in chloroplast thylakoid membranes, apparently, restrict lipid fatty acyl chain segmental mobility from 9th to 16th carbons vis a vis their liposomal counterparts. Surprisingly, liposomal fatty acyl chains are more restricted at 5th and 7th carbon positions as compared at these positions in thylakoid membranes. This is explainable as due to motional restricting effect at these positions, because of steric hindrance by large chlorophyll headgroups, specially so, in liposomes. However, in native thylakoid membranes, chlorophylls are mainly complexed with proteins as light-harvesting complexes and may not largely be free to restrain lipid fluidity, as such.
Diffusion coefficients
Diffusion coefficients of fluorescent lipid analogues are about 10−8cm2/s in fluid lipid membranes. In gel lipid membranes and natural biomembranes, the diffusion coefficients are about 10−11cm2/s to 10−9cm2/s.
Charged lipid membranes
The melting of charged lipid membranes, such as 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol, can take place over a wide range of temperature. Within this range of temperatures, these membranes become very viscous.
Biological relevance
Microorganisms subjected to thermal stress are known to alter the lipid composition of their cell membrane (see homeoviscous adaptation). This is one way they can adjust the fluidity of their membrane in response to their environment. Membrane fluidity is known to affect the function of biomolecules residing within or associated with the membrane structure. For example, the binding of some peripheral proteins is dependent on membrane fluidity. Lateral diffusion (within the membrane matrix) of membrane-related enzymes can affect reaction rates. Consequently, membrane-dependent functions, such as phagocytosis and cell signalling, can be regulated by the fluidity of the cell-membrane.
See also
Annular lipid shell
Homeoviscous adaptation
Lipid bilayer
Lipid bilayer phase behavior
Liposome
Saffman–Delbrück model
References
Membrane biology
Lipids | Membrane fluidity | [
"Chemistry"
] | 2,153 | [
"Biomolecules by chemical classification",
"Membrane biology",
"Organic compounds",
"Molecular biology",
"Lipids"
] |
8,871,974 | https://en.wikipedia.org/wiki/Ethnoornithology | Ethnoornithology (also ethno-ornithology) is the study of the relationship between people and birds (from "ethno-" - relating to people and culture - and "ornithology" - the study of birds). It is a branch of ethnozoology and so of the wider field of ethnobiology. Ethnoornithology is an interdisciplinary subject and combines anthropological, cognitive and linguistic perspectives with natural scientific approaches to the description and interpretation of people's knowledge and use of birds. Like ethnoscience and other cognate terms, "ethnoornithology" is sometimes used narrowly to refer to people's practice rather than the study of that practice. The broader focus is on how birds are perceived, used and managed in human societies, including their use for food, medicine and personal adornment, as well as their use in divination and ritual. Applied ethnoornithological research is also starting to play an increasingly important role in the development of conservation initiatives.
History of ethnoornithology
The work of Ralph Bulmer in New Guinea, culminating in his collaboration with Ian Saem Majnep in writing Birds of My Kalam Country (1977), set a new standard for ethnoornithological research, and this book has deservedly become a classic of modern ethno-ornithology.
Approaches to ethnoornithology
Ethnoornithology and conservation
Like other branches of ethnozoology, ethnoornithology has been long undervalued as a resource for conservation, though this is now beginning to change. Mark Bonta's Seven Names for the Bellbird (2003), which highlights the importance of local traditions and practices relating to birds for the future of biodiversity conservation in Honduras, and Ricardo Rozzi's Multi-ethnic Bird Guide of the Subantarctic Forests of South America (2003), which focuses on the integration of traditional ornithological knowledge and environmental ethics in southern Chile, provide good examples of this trend. Soma (2015) pointed out that ethnoornithological knowledge of falconers contribute to conservation for local avifauna (especially focusing on Kazakh eagle masters). This realisation is the basis for founding the Ethno-ornithology World Archive (EWA), a collaborative project between Oxford University (linking the Department of Zoology and School of Anthropology and Museum Ethnography) and BirdLife International.
Professional associations
The Society of Ethnobiology, which publishes the Journal of Ethnobiology, provides a general forum for ethnobiological - including ethnoornthological - research. In January 2006, the Ethnoornithology Research & Study Group (ERSG) was established "to provide a clearinghouse, information source and discussion point for people interested in the study of, research about and application of indigenous bird knowledge".
References
Aillapan L. & R. Rozzi. 2001. Twenty Winged Poems from the native forests of southern Chile. Two CDs of indigenous poems by the Mapuche shaman Lorenzo Aillapán, recorded in the forests of southern Chile in combination with bird vocalizations. Contain a book with an explanatory preface and bilingual text Mapudungún-English of the poems with illustration of the birds by D. Martínez. General direction and design by Ricardo Rozzi. Editorial Plaza y Valdés, Mexico.
Bonta, M. (2003). Seven Names for the Bellbird: Conservation Geography in Honduras. College Station: Texas A&M University Press.
Feld, S. (1982). Sound and Sentiment: Birds, Weeping, Poetics, and Song in Kaluli Expressions. Philadelphia: University of Pennsylvania Press. (2nd edition published in 1990).
Forth, G. (2004). Nage Birds: Classification and Symbolism among an Eastern Indonesian People. London & New York: Routledge.
Majnep, I.S. & Bulmer, R.B. (1977). Birds of My Kalam Country. Auckland: Auckland University Press.
Paredes-Castellanos, A., & Rozzi, R. (2018). Biocultural exoticism in the feminine landscape of Latin America. In From Biocultural Homogenization to Biocultural Conservation (pp. 167–183). Springer, Cham.
Tidemann, S. & Gosler, A. (2010). Ethno-ornithology: Birds, Indigenous Peoples, Cultures, and Society. London: Earthscan (Routledge).
Soma, Takuya. (2015). "Human & Raptor Interactions in the Context of a Nomadic Society: Anthropological and Ethno-Ornithological Studies of Altaic Kazakh Falconry and its Cultural Sustainability in Western Mongolia". Germany: University of Kassel Press.
External links
Ethnoornithology Research & Study Group (ESRG)
Society of Ethnobiology
Field notes on ethnoornithology in Kenya
Interview by the Chilean poet Cristian Warnken with the Mapuche Birdman Lorenzo Aillapan and the Biocultural Conservationist and philosopher Ricardo Rozzi
Bird - Native Forest by Chilean film maker Olaf Pena, with the Mapuche Birdman Lorenzo Aillapan and the Biocultural Conservationist and philosopher Ricardo Rozzi
Ethnobiology
Anthropology
Ethnography
Ornithology | Ethnoornithology | [
"Biology",
"Environmental_science"
] | 1,118 | [
"Environmental social science",
"Ethnobiology"
] |
8,872,460 | https://en.wikipedia.org/wiki/Interpolation%20theory | The Interpolation Theory, also known as the Intercalation Theory or the Antithetic Theory, is a theory that attempts to explain the origin of the alternation of generations in plants. The Interpolation Theory suggests that the sporophyte generation progenated from a haploid, green algal thallus in which repeated mitotic cell divisions of a zygote produced an embryo retained on the thallus and gave rise to the diploid phase (sporophyte). Ensuing evolution caused the sporophyte to become increasingly complex, both organographically and anatomically.
The Interpolation Theory was introduced by Čelakovský (1874) as the Antithetic Theory. Bower (1889) further developed this theory and renamed it the Interpolation Theory. The theory was later supported by Overton (1893), Scott (1896), Strasburger (1897), Williams (1904), and others.
The gradual evolution of an independent, sporophyte phase was viewed by Bower as being closely related to the transition from aquatic to terrestrial plant life on Earth.
Evidence supporting this theory can be found in the life cycle of modern Bryophytes in which the sporophyte is physiologically dependent on the gametophyte. Competing theories include the Transformation theory, which was introduced as the Homologous theory by Čelakovský, and also renamed by Bower.
References
Gifford, Ernest M. and Adriance S. Foster. Morphology and Evolution of Vascular Plants, Third Edition. New York: W.H. Freeman and Company, 1988. 15–19.
Sinha, A.K. and Anil Kumar. Botany for Degree Students – Pteridophyta. S. Chand. 9–10.
Chopra, R.N., P.K. Kumra. Biology of Bryophytes. New Age International Publishers. 125.
How Plants Conquered the Land. Hans' Paleobotany Pages.
Biology theories | Interpolation theory | [
"Biology"
] | 410 | [
"Biology theories"
] |
8,873,033 | https://en.wikipedia.org/wiki/List%20of%20home%20computers%20by%20video%20hardware | This is a list of home computers, sorted alphanumerically, which lists all relevant details of their video hardware.
Home computers are the second generation of desktop computers, entering the market in 1977 and becoming common during the 1980s. A decade later they were generally replaced by IBM PC compatible "PCs", although technically home computers are also classified as personal computers.
Examples of early home computers are the TRS-80, Atari 8-bit computers, BBC Micro, ZX Spectrum, MSX, Amstrad CPC 464, and Commodore 64. Examples of late home computers are MSX 2 systems, and the Amiga and Atari ST systems.
Note: in cases of manufacturers who have made both home and personal computers, only machines fitting into the home computer category are listed. Systems in the personal computer category, except for Early Macintosh PCs, are generally based on the VGA standard and use a video chip known as a Graphics Processing Unit. Very early PCs used one of the much simpler (even compared to most home computer video hardware) video display controller cards, using parts like the MDA, the Hercules Graphics Card, the CGA and the EGA standard). Only after the introduction of the VGA standard could PCs really compete with the home computers of the same era, such as the Amiga and Atari ST, or even with the MSX-2. Also, not listed are systems that are typically only gaming systems, like the Atari 2600 and the Bally Astrocade, even though these systems could sometimes be upgraded to resemble a home computer.
The importance of having capable video hardware
Early home computers all used similar hardware and software, mostly using the 6502, the Z80, or in a few cases the 6809 microprocessor. They could have as little as 1 KB of RAM or as much as 128K, and software-wise, they could use a small 4K BASIC interpreter, or an extended 12K or more BASIC. The basic systems were quite similar with the exception of the video display hardware. As a result, the success of a system proved to primarily rely on the performance of the video display hardware, since this had a direct implication on the kind of games that could be played on the system.
The most important aspect of a home computer was how far programmers could push the hardware to create games. A case in point is the Commodore 64. Its microprocessor lacked advanced math functions and was relatively slow. In addition, the built-in BASIC interpreter lacked any sort of graphics commands, as it was the same version that was developed for the older Commodore PET (a computer without any high-resolution graphics capabilities at all). However, these drawbacks were of little consequence, because the C64 had the VIC-II chip. When accessed by machine language programs, the graphic capabilities of this chip made it practical to develop arcade-style games on a home system. Additionally, specific machine language code exploiting quirks of the VIC-II chip allowed for special tricks to draw even better pictures out of the VIC-II chip. The comparatively large memory and the audio capabilities of the C64 also lent themselves well toward the production of larger games.
An example of the opposite is the Aquarius by Mattel which had such incredibly limited video hardware that it was retracted from the market after only four months due to poor sales.
Video arbitration logic
One major problem that early computer video hardware had to overcome was the video bus arbitration problem. The problem was determining a way to give both the video hardware (VDU) and the CPU continuous read access to the video RAM. The obvious solution, using interleaving time slots for the VDU and RAM was hard to implement because the logic circuits and video memory chips of the time did not have the switching speed necessary to do so. For higher resolutions, the logic and the memory chips were barely fast enough to support reading the display data, let alone for dedicating half the available time for the slow 8-bit CPU. That being said, one system, the Apple II, was one of the first to use a feature of the data-bus logic of the 6502 processor to implement a very early interleaving time slot mechanism to eliminate this problem. The BBC Micro used 4 MHz RAM with a 2 MHz 6502 in order to interleave video accesses with CPU accesses.
Most other systems used a much simpler approach, and the TRS-80's video logic was so primitive that it simply did not have any bus arbitration at all. The CPU had access to the video memory at all times. Writing to the video RAM simply disabled the video display logic. The result was that the screen often displayed random horizontal black stripes on screen when there was heavy access to the video RAM, like during a video game.
Most systems avoided the problem by having a status register that the CPU could read, and which showed when the CPU could safely write to the video memory. That was possible because a composite video signal blanks the video output signal during the "blanking periods" of the horizontal and especially the long vertical video sync pulses. So by simply waiting for the next blanking period, the stripes were avoidable. This approach did have one disadvantage, it relied on the software not to write to the screen during the non-blanking periods. If the software ignored the status register the stripes would re-appear. Another approach, used by most other machines of the time, was to temporarily stop the CPU using the "WAIT/BUSRQ" (Z80) "WAIT" (6809) or "SYNC" (6502) control signal whenever the CPU tried to write to the screen during a non-blanking period. Yet another, more advanced, the solution was to add a hardware FIFO so that the CPU could write to the FIFO instead of directly to the RAM chips, which were updated from the FIFO during a blanking interval by special logic circuitry. Some later systems started using special "two-port" video memory, called VRAM, that had independent data output pins for the CPU interface and the video logic.
The main classes of video hardware
There are two main categories of solutions for a home computer to generate a video signal:
A custom design, either built from discrete logic chips or based around some kind of custom logic chips (an ASIC or PLD).
A system using some form of video display controller (VDC), a VLSI chip that contained most of the logic circuitry needed to generate the video signal
Systems in the first category were the most flexible and could offer a wide range of (sometimes unique) capabilities, but generally speaking, the second category could offer a much more complex system for a comparatively lower price.
The VDC based systems can be divided into four sub-categories:
Simple video shift register based solutions, have a simple "video shifter chip", and the main CPU doing most of the complex stuff. Only one example of such a chip for a home computer exists, the RCA CDP1861 used in the COSMAC VIP. It could only create a very low-resolution monochrome graphic screen. The chip in the Sinclair ZX-81 also is a video shifter but is a custom logic chip (a ULA) rather than a single-purpose commercial IC like the CDP1861. Dedicated Video shifter chips did have some use in very early game systems, most notably the Television Interface Adaptor chip in the Atari 2600. Note that although one of the chips in an Atari ST is also called a "video shift register" it does not fall into this class, mainly because the IC's in this class depends on the main CPU to feed them with picture data. They do nothing more than generating the sync signals and convert parallel data into a serial video data stream. The Atari ST's chip used a DMA system to read out video data independent of the main CPU and contained a palette RAM, and resolution/color mode switching logic.
CRTC (Cathode Ray Tube Controller) based solutions. A CRTC is a chip that generates most of the basic timing and control signals. It must be complemented with some "Video RAM" and some other logic for the "arbitration" so that the CPU and the CRTC chip can share access to this RAM. To complete the design, a CRTC chip also needs some other support logic. For example, a ROM containing the bitmap font for text modes, and logic to convert the output from the system into a video signal.
Video interface controllers were a step up on the ladder, these were true VLSI chips that integrated all of the logic that was in a typical CRTC based system, plus a lot more, into a single chip. The VIC-II chip is probably the best-known chip of this category.
Video co-processor chips are at the highest end of the scale; Video interface controllers that can manipulate, and/or interpret and display, the contents of their own dedicated Video RAM without intervention from the main CPU. These chips are highly flexible offering options and features with minimal CPU involvement that on other systems are impossible or at best difficult to produce, requiring extensive CPU overhead. The Atari ANTIC/GTIA and Amiga OCS/ECS/AGA are well known examples of this high-feature category. But note that not all video co-processors are powerful, some are even simpler than many Video interface controllers, notably the primitive SAA5243 which is still technically a co-processor.
Explanation of the terms used in the tables
System Name The name of the system, or if there are many similar versions, the name of the most well-known variant, see Notes.
Year The year that the first version of this system came on the market.
Chip name The name of the chip that was used as the basis for the video logic.
Video RAM The maximum amount of RAM used for the video display, depending on the resolution used the system may use less.
Video mode(s) [i.e. Text mode(s) and Graphics modes] The numbers of characters per line and lines of text the system supported and the number of colors they could have. Sometimes more than one mode was possible: The number of horizontal and Vertical pixels the system could display in a high resolution mode and The number of colors each pixel could have in High-resolution mode, where several high-resolution modes exist each one is listed separately. Beginning with the Xerox Alto, systems forwent independent text modes and drew text on a high-resolution graphics screen. This required more video RAM, but also freed computer fonts from a fixed grid.
Font extras Describes extra graphical possibilities a video system had because of optional features of their character sets, there are currently three categories:
LC Some systems could only display upper case characters in text mode because of their limited character set, If a system was able to also support lower case letters in a text mode, (in any high-resolution mode it is of course always possible), then there is LC (for Lower Case) in this column.
BG Some systems used a matrix of blocky pixels instead of a letter in their font sets (or used dedicated hardware to emulate them, like the TRS-80 did), to support some sort of all points addressable (APA) mode. It's hard to call this a "high resolution" mode because the resolution could be as low as 80×48 pixels, but in any case, it was possible to draw pictures with them. In the case of systems that used such a system as its "APA" mode, there is BG (for Block Graphics) in this column.
SG Some other systems used semi graphical characters like box-drawing characters dots and card symbols, and "graphical building block" geometric shapes such as triangles to give the system the appearance it could do high-resolution graphics while in reality it could not, Systems like that have SG (for semi graphical characters) in this column. Many systems like the PET had a few of such characters dedicated to blocking graphics for an APA mode as well, often only for 2×2 matrix characters. Sometimes the system filled (or could fill) a reprogrammable section of the font set which such characters, these systems mainly fall under the "soft font" heading. Note that the BG and SG entries are only used when the system relied on them, had them predefined in its default character set, or, (what often happened on early systems) had them printed on the keyboard keys for direct entry in combination with some kind of "graphic shift" key.
Soft font When the system had a programmable font RAM instead of a static "font ROM", or when the video system did not have a hardware text mode, but painted text in the high-res screen using software, the video display wasn't dependent on a permanent font set, in this case we are talking about a system with a "soft" font.
Color resolution in "high-resolution mode" it was often the case that a certain pixel could not be given an arbitrary color, often certain clusters of pixels, (quite often 8×8 pixels large) shared the same "color attribute", so as to spare video memory, as an 8-bit computer only had a 64 KB address space, and the CPU often had limited capabilities to manipulate video memory, therefore it was often necessary to keep the video RAM size as small as possible, so a minimum of the address space of the micro was used, and also the video content could be changed relatively rapidly.
Palette support If the system could translate a "logical color" into a (larger number) or true colors using a palette mechanism then this column lists the number of logical colors the palette could accept, and the number of colors it could translate to.
HW accel Short for "hardware acceleration", can take several forms, the most obvious form is "bit blitting", that is the moving of groups of pixels from one place in video memory to another without the CPU doing any of the moving, another often-used technique is hardware scrolling which in fact emulates moving the whole screen in the video RAM, the third form of hardware acceleration is the use of sprites implemented in hardware. Some systems also supported drawing lines (and sometimes rectangles) using special line drawing hardware. The entry in the column reveals which methods the hardware supported with two letters for each method.
BL For blitter
DR For hardware supported line drawing
SC For hardware scrolling support
SP For hardware sprite support
TE For hardware Tile engine support in graphic mode
Sprite details Covers three facets of the sprite support hardware the system used. Each number in the table cell is preceded by two letters.
S# For the first facet, is the total number of hardware sprites the system could support, in hardware (not counting re-use of the same hardware). if the system doesn't support hardware sprites at all the table cell only contains "-" . If S# is 1 then the single sprite is most often used to support a mouse cursor.
SS For the second facet, is the size of the sprite in screen pixels. A sprite could be displayed by the hardware, as a matrix of horizontal by vertical pixels. If more than one sprite size mode is available each one is listed.
SC For the third facet, is the number of sprite colors, it gives the number of colors that a sprite could have. It is about the total number of colors that could be used to define the sprite (transparent NOT included), so if a sprite could only be displayed as a figure in a single color the number is 1. If more than one sprite color mode is available each one is listed.
SP For the fourth facet, is the number of sprites per scan line. Hardware sprites use a kind of Z-buffer to determine which sprite is "on top". Availability of hardware to do this limits the number of sprites that can be displayed on each scan line. This number tells how many sprites could be displayed on a scanline before one of them became invisible because of hardware limitations.
Unique features If the video display has unique features (or limitations) they will be listed here, if space is a limitation the remaining special features are expressed as notes.
A "-" in a table cell means that the answer is irrelevant, unknown, or in another way has no meaning, for example, the sprite size of a system that does not support hardware sprites.
A "?" in a table cell means that the entry has not yet been determined. if a ? follows an entry it means that other options than the listed ones may also exist
"Mono" in a table cell means monochrome that is, for example, black on white, or black on green.
The list of home computers and their video capabilities
Systems with video logic designed as terminals
Systems using software-driven video generation
Systems using discrete logic
With independent text mode(s)
Without independent text mode(s)
Systems using simple Video Shift Registers
Systems using custom logic ICs
With independent text mode(s)
Without independent text mode(s)
Systems using a CRTC
MC6845 or second source
With independent text mode(s)
Without independent text mode(s)
Other models
Systems using a Video Interface Controller
MC6847 or second source
Other models
With independent text mode(s)
Without independent text mode(s)
Systems using a video co-processor
With independent text mode(s)
Without independent text mode(s)
Systems that fall into multiple classifications
For these systems, it is established that they are based on multiple technologies. The hardware chosen to be used by these systems may have a substantial or insubstantial impact on the video they output.
Systems that could not be classified
For these systems, it could not be established what technology they are based on, therefore, some information regarding them may be inaccurate.
See also
List of computer hardware palettes
Semi graphical characters
Semigraphics
Video Display Controller
Notes
Home computers by video hardware
Graphics chips
Graphics hardware
Home computers by video hardware
Video game development | List of home computers by video hardware | [
"Technology"
] | 3,694 | [
"Computing-related lists",
"Lists of computer hardware"
] |
8,873,997 | https://en.wikipedia.org/wiki/Mz%201 | Mz 1 (Menzel 1), is a bipolar planetary nebula (PN) in the constellation Norma.
Characteristics
Menzel 1 is a bright planetary nebula that has a prominent central ring of enhanced emission. One model of its structure is a three-dimensional hour-glass shape with a smoothly decreasing density starting from the waist or equator as measured outwardly to the poles. It is radially expanding at a rate of about 23 km/s and estimated to be around 4,500 to 10,000 years old and has its polar axis oriented at an angle of around 40° from the plane of the sky. Its central star is estimated to have a mass of . In 1992 Schwarz, Corradi, & Melnick published narrow band images of Mz 1 in Hα and [OIII]. H2 emission was observed in Mz 1 by
Webster, Payne, Storey, Dopita (1988). However, despite its relative brightness, Mz 1 has only been studied in a few papers .
History
Mz 1 was discovered by Donald Howard Menzel in 1922.
Notes
3,400 ± 500 ly distance × sin( 76 diameter_angle / 2 ) = 0.63 ± 0.09 ly. radius
12.0 apparent magnitude - 5 * (log10(1,050 ± 150 pc distance) - 1) = 1.9 ± 0.3 absolute magnitude
References
(archive)
External links
http://www.astro.washington.edu/users/balick/PNIC/PNimages_by_galcoord/322.4-02.6.Mz1.jpg
Planetary nebulae
Norma (constellation)
? | Mz 1 | [
"Astronomy"
] | 344 | [
"Norma (constellation)",
"Constellations"
] |
8,874,156 | https://en.wikipedia.org/wiki/LSm | In molecular biology, LSm proteins are a family of RNA-binding proteins found in virtually every cellular organism. LSm is a contraction of 'like Sm', because the first identified members of the LSm protein family were the Sm proteins. LSm proteins are defined by a characteristic three-dimensional structure and their assembly into rings of six or seven individual LSm protein molecules, and play a large number of various roles in mRNA processing and regulation.
The Sm proteins were first discovered as antigens targeted by so-called anti-Sm antibodies in a patient with a form of systemic lupus erythematosus (SLE), a debilitating autoimmune disease. They were named Sm proteins in honor of Stephanie Smith, a patient who suffered from SLE. Other proteins with very similar structures were subsequently discovered and named LSm proteins. New members of the LSm protein family continue to be identified and reported.
Proteins with similar structures are grouped into a hierarchy of protein families, superfamilies, and folds. The LSm protein structure is an example of a small beta sheet folded into a short barrel. Individual LSm proteins assemble into a six or seven member doughnut ring (more properly termed a torus), which usually binds to a small RNA molecule to form a ribonucleoprotein complex. The LSm torus assists the RNA molecule to assume and maintain its proper three-dimensional structure. Depending on which LSm proteins and RNA molecule are involved, this ribonucleoprotein complex facilitates a wide variety of RNA processing including degradation, editing, splicing, and regulation.
Alternate terms for LSm family are LSm fold and Sm-like fold, and alternate capitalization styles such as lsm, LSM, and Lsm are common and equally acceptable.
History
Discovery of the Smith antigen
The story of the discovery of the first LSm proteins begins with a young woman, Stephanie Smith, who was diagnosed in 1959 with systemic lupus erythematosus (SLE), eventually succumbing to complications of the disease in 1969 at the age of 22. During this period, she was treated at New York's Rockefeller University Hospital, under the care of Dr. Henry Kunkel and Dr. Eng Tan. As those with an autoimmune disease, SLE patients produce antibodies to antigens in their cells' nuclei, most frequently to their own DNA. However, Kunkel and Tan found in 1966 that Smith produced antibodies to a set of nuclear proteins, which they named the 'smith antigen' (Sm Ag). About 30% of SLE patients produce antibodies to these proteins, as opposed to double stranded DNA. This discovery improved diagnostic testing for SLE, but the nature and function of this antigen was unknown.
Sm proteins, snRNPs, the spliceosome and messenger RNA splicing
Research continued during the 1970s and early 1980s. The smith antigen was found to be a complex of ribonucleic acid (RNA) molecules and multiple proteins. A set of uridine-rich small nuclear RNA (snRNA) molecules was part of this complex, and given the names U1, U2, U4, U5 and U6. Four of these snRNAs (U1, U2, U4 and U5) were found to be tightly bound to several small proteins, which were named SmB, SmD, SmE, SmF, and SmG in decreasing order of size. SmB has an alternatively spliced variant, SmB', and a very similar protein, SmN, replaces SmB'/B in certain (mostly neural) tissues. SmD was later discovered to be a mixture of three proteins, which were named SmD1, SmD2 and SmD3. These nine proteins (SmB, SmB', SmN, SmD1, SmD2, SmD3, SmE, SmF and SmG) became known as the Sm core proteins, or simply Sm proteins. The snRNAs are complexed with the Sm core proteins and with other proteins to form particles in the cell's nucleus called small nuclear ribonucleoproteins, or snRNPs. By the mid-1980s, it became clear that these snRNPs help form a large (4.8 MD molecular weight) complex, called the spliceosome, around pre-mRNA, excising portions of the pre-mRNA called introns and splicing the coding portions (exons) together. After a few more modifications, the spliced pre-mRNA becomes messenger RNA (mRNA) which is then exported from the nucleus and translated into a protein by ribosomes.
Discovery of proteins similar to the Sm proteins
The snRNA U6 (unlike U1, U2, U4 and U5) does not associate with the Sm proteins, even though the U6 snRNP is a central component in the spliceosome. In 1999 a protein heteromer was found that binds specifically to U6, and consisted of seven proteins clearly homologous to the Sm proteins. These proteins were denoted LSm (like Sm) proteins (LSm1, LSm2, LSm3, LSm4, LSm5, LSm6 and LSm7), with the similar LSm8 protein identified later. In the bacterium Escherichia coli, the Sm-like protein HF-I encoded by the gene hfq was described in 1968 as an essential host factor for RNA bacteriophage Qβ replication. The genome of Saccharomyces cerevisiae (Baker's Yeast) was sequenced in the mid-1990s, providing a rich resource for identifying homologs of these human proteins. Subsequently, as more eukaryotes genomes were sequenced, it became clear that eukaryotes, in general, share homologs to the same set of seven Sm and eight LSm proteins. Soon after, proteins homologous to these eukaryote LSm proteins were found in Archaea (Sm1 and Sm2) and Bacteria (Hfq and YlxS homologs). The archaeal LSm proteins are more similar to the eukaryote LSm proteins than either are to bacterial LSm proteins. The LSm proteins described thus far were rather small proteins, varying from 76 amino acids (8.7 kD molecular weight) for human SmG to 231 amino acids (29 kD molecular weight) for human SmB. But recently, larger proteins have been discovered that include a LSm structural domain in addition to other protein structural domains (such as LSm10, LSm11, LSm12, LSm13, LSm14, LSm15, LSm16, ataxin-2, as well as archaeal Sm3).
Discovery of the LSm fold
Around 1995, comparisons between the various LSm homologs identified two sequence motifs, 32 nucleic acids long (14 amino acids), that were very similar in each LSm homolog, and were separated by a non-conserved region of variable length. This indicated the importance of these two sequence motifs (named Sm1 and Sm2), and suggested that all LSm protein genes evolved from a single ancestral gene. In 1999, crystals of recombinant Sm proteins were prepared, allowing X-ray crystallography and determination of their atomic structure in three dimensions. This demonstrated that the LSm proteins share a similar three-dimensional fold of a short alpha helix and a five-stranded folded beta sheet, subsequently named the LSm fold. Other investigations found that LSm proteins assemble into a torus (doughnut-shaped ring) of six or seven LSm proteins, and that RNA binds to the inside of the torus, with one nucleotide bound to each LSm protein.
Structure
Uridine phosphate binds in archaeal Sm1 between the β2b/β3a loop and β4b/β5 loop. The uracil is stacked between the histidine and arginine residues, stabilized by hydrogen bonding to an asparagine residue, and hydrogen bonding between the aspartate residue and the ribose. LSm proteins are characterized by a beta sheet (the secondary structure), folded into the LSm fold (the tertiary structure), polymerization into a six or seven member torus (the quaternary structure), and binding to RNA oligonucleotides. A modern paradigm classifies proteins on the basis of protein structure and is a currently active field, with three major approaches, SCOP (Structural Classification of Proteins), CATH (Class, Architecture, Topology, Homologous superfamily), and FSSP/DALI (Families of Structurally Similar Proteins).
Secondary
The secondary structure of a LSm protein is a small five-strand anti-parallel beta sheet, with the strands identified from the N-terminal end to the C-terminal end as β1, β2, β3, β4, β5. The SCOP class of All beta proteins and the CATH class of Mainly Beta are defined as protein structures that are primarily beta sheets, thus including LSm. The SM1 sequence motif corresponds to the β1, β2, β3 strands, and the SM2 sequence motif corresponds to the β4 and β5 strands. The first four beta strands are adjacent to each other, but β5 is adjacent to β1, turning the overall structure into a short barrel. This structural topology is described as 51234. A short (two to four turns) N-terminal alpha helix is also present in most LSm proteins. The β3 and β4 strands are short in some LSm proteins, and are separated by an unstructured coil of variable length. The β2, β3 and β4 strands are strongly bent about 120° degrees at their midpoints The bends in these strands are often glycine, and the side chains internal to the beta barrel are often the hydrophobic residues valine, leucine, isoleucine and methionine.
Tertiary
SCOP simply classifies the LSm structure as the Sm-like fold, one of 149 different Beta Protein folds, without any intermediate groupings. The LSm beta sheet is sharply bent and described as a Roll architecture in CATH (one of 20 different beta protein architectures in CATH). One of the beta strands (β5 in LSm) crosses the open edge of the roll to form a small SH3 type barrel topology (one of 33 beta roll topologies in CATH). CATH lists 23 homologous superfamilies with an SH3 type barrel topology, one of which is the LSm structure (RNA Binding Protein in the CATH system). SCOP continues its structural classification after Fold to Superfamily, Family and Domain, while CATH continues to Sequence Family, but these divisions are more appropriately described in the "Evolution and phylogeny" section.
The SH3-type barrel tertiary structure of the LSm fold is formed by the strongly bent (about 120°) β2, β3 and β4 strands, with the barrel structure closed by the β5 strand. Emphasizing the tertiary structure, each bent beta strand can be described as two shorter beta strands. The LSm fold can be viewed as an eight-strand anti-parallel beta sandwich, with five strands in one plane and three strands in a parallel plane with about a 45° pitch angle between the two halves of the beta sandwich. The short (two to four turns) N-terminal alpha helix occurs at one edge of the beta sandwich. This alpha helix and the beta strands can be labeled (from the N-terminus to the C-terminus) α, β1, β2a, β2b, β3a, β3b, β4a, β4b, β5 where the a and b refer to either the two halves of a bent strand in the five-strand description, or to the individual strands in the eight-strand description. Each strand (in the eight-strand description) is formed from five amino acid residues. Including the bends and loops between the strands, and the alpha helix, about 60 amino acid residues contribute to the LSm fold, but this varies between homologs due to variation in inter-strand loops, the alpha helix, and even the lengths of β3b and β4a strands.
Quaternary
LSm proteins typically assemble into a LSm ring, a six or seven member torus, about 7 nanometers in diameter with a 2 nanometer hole. The ancestral condition is a homohexamer or homoheptamer of identical LSm subunits. LSm proteins in eukaryotes form heteroheptamers of seven different LSm subunits, such as the Sm proteins. Binding between the LSm proteins is best understood with the eight-strand description of the LSm fold. The five-strand half of the beta sandwich of one subunit aligns with the three-strand half of the beta sandwich of the adjacent subunit, forming a twisted 8-strand beta sheet Aβ4a/Aβ3b/Aβ2a/Aβ1/Aβ5/Bβ4b/Bβ3a/Bβ2b, where the A and B refer to the two different subunits. In addition to hydrogen bonding between the Aβ5 and Bβ4b beta strands of the two LSm protein subunits, there are energetically favorable contacts between hydrophobic amino acid side chains in the interior of the contact area, and energetically favorable contacts between hydrophilic amino acid side chains around the periphery of the contact area.
RNA oligonucleotide binding
LSm rings form ribonucleoprotein complexes with RNA oligonucleotides that vary in binding strength from very stable complexes (such as the Sm class snRNPs) to transient complexes. RNA oligonucleotides generally bind inside the hole (lumen) of the LSm torus, one nucleotide per LSm subunit, but additional nucleotide binding sites have been reported at the top (α helix side) of the ring. The exact chemical nature of this binding varies, but common motifs include stacking the heterocyclic base (often uracil) between planar side chains of two amino acids, hydrogen bonding to the heterocyclic base and/or the ribose, and salt bridges to the phosphate group.
Functions
The various kinds of LSm rings function as scaffolds or chaperones for RNA oligonucleotides, assisting the RNA to assume and maintain the proper three-dimensional structure. In some cases, this allows the oligonucleotide RNA to function catalytically as a ribozyme. In other cases, this facilitates modification or degradation of the RNA, or the assembly, storage, and intracellular transport of ribonucleoprotein complexes.
Sm ring
The Sm ring is found in the nucleus of all eukaryotes (about 2.5 × 106 copies per proliferating human cell), and has the best understood functions. The Sm ring is a heteroheptamer. The Sm-class snRNA molecule (in the 5' to 3' direction) enters the lumen (doughnut hole) at the SmE subunit and proceeds sequentially in a clockwise fashion (looking from the α helix side) inside the lumen (doughnut hole) to the SmG, SmD3, SmB, SmD1, SmD2 subunits, exiting at the SmF subunit. (SmB can be replaced by the splice variant SmB' and by SmN in neural tissues.) The Sm ring permanently binds to the U1, U2, U4 and U5 snRNAs which form four of the five snRNPs that constitute the major spliceosome. The Sm ring also permanently binds to the U11, U12 and U4atac snRNAs which form four of the five snRNPs (including the U5 snRNP) that constitute the minor spliceosome. Both of these spliceosomes are central RNA-processing complexes in the maturation of messenger RNA from pre-mRNA. Sm proteins have also been reported to be part of ribonucleoprotein component of telomerase.
Lsm2-8 ring
The two Lsm2-8 snRNPs (U6 and U6atac) have the key catalytic function in the major and minor spliceosomes. These snRNPs do not include the Sm ring, but instead use the heteroheptameric Lsm2-8 ring. The LSm rings are about 20 times less abundant than the Sm rings. The order of these seven LSm proteins in this ring is not known, but based on amino acid sequence homology with the Sm proteins, it is speculated that the snRNA (in the 5' to 3' direction) may bind first to LSm5, and precedes sequentially clockwise to the LSm7, LSm4, LSm8, LSm2, LSm3, and exiting at the LSm6 subunit. Experiments with Saccharomyces cerevisiae (budding yeast) mutations suggest that the Lsm2-8 ring assists the reassociation of the U4 and U6 snRNPs into the U4/U6 di-snRNP. (After completion of exon deletion and intron splicing, these two snRNPs must reassociate for the spliceosome to initiate another exon/intron splicing cycle. In this role, the Lsm2-8 ring acts as an RNA chaperone instead of an RNA scaffold.) The Lsm2-8 ring also forms an snRNP with the U8 small nucleolar RNA (snoRNA) which localizes in the nucleolus. This ribonucleoprotein complex is necessary for processing ribosomal RNA and transfer RNA to their mature forms. The Lsm2-8 ring is reported to have a role in the processing of pre-P RNA into RNase P RNA. In contrast to the Sm ring, the Lsm2-8 ring does not permanently bind to its snRNA and snoRNA.
Sm10/Sm11 ring
A second type of Sm ring exists where LSm10 replaces SmD1 and LSm11 replaces SmD2. LSm11 is a two domain protein with the C-terminal domain being a LSm domain. This heteroheptamer ring binds with the U7 snRNA in the U7 snRNP. The U7 snRNP mediates processing of the 3' UTR stem-loop of the histone mRNA in the nucleus. Like the Sm ring, it is assembled in the cytoplasm onto the U7 snRNA by a specialized SMN complex.
Lsm1-7 ring
A second type of Lsm ring is the Lsm1-7 ring, which has the same structure as the Lsm2-8 ring except that LSm1 replaces LSm8. In contrast to the Lsm2-8 ring, the Lsm1-7 ring localizes in the cytoplasm where it assists in degrading messenger RNA in ribonucleoprotein complexes. This process controls the turnover of messenger RNA so that ribosomal translation of mRNA to protein responds quickly to changes in transcription of DNA to messenger RNA by the cell. LSM1-7, together with Pat1, has been shown to play a role in the formation of P-bodies after deadenylation.
Gemin6 and Gemin7
The SMN complex (described under "Biogenesis of snRNPs") is composed of the SMN protein and Gemin2-8. Two of these, Gemin 6 and Gemin7 have been discovered to have the LSm structure, and to form a heterodimer. These may have a chaperone function in the SMN complex to assist the formation of the Sm ring on the Sm-class snRNAs. PRMT5 complex is composed of PRMT5, pICln, WD45 (Mep50). pICln helps to form Sm opened ring on SMN complex. SMN complex assists in the assembly of snRNPs where the Sm ring is in the open conformation on SMN complex and this Sm ring is loaded onto the snRNA by SMN complex.
LSm12-16 and other multi-domain LSm proteins
The LSm12-16 proteins have been described very recently. These are two-domain proteins with a N-terminal LSm domain and a C-terminal methyl transferase domain. Very little is known about the function of these proteins, but presumably they are member of LSm-domain rings that interact with RNA. There is some evidence that LSm12 is possibly involved in mRNA degradation and LSm13-16 may have roles in regulation of mitosis. Unexpectedly, LSm12 was recently implicated in calcium signaling by acting as the intermediate binding-protein for the nucleotide second messenger, NAADP (nicotinic acid adenine dinucleotide phosphate) that activates endo-lysosomal Ca2+ channels TPCs (two-pore channels). This occurred by NAADP binding to the LSm domain, not the AD domain. A large protein of unknown function, ataxin-2, associated with the neurodegenerative disease spinocerebellar ataxia type 2, also has a N-terminal LSm domain.
Archaeal Sm rings
Two LSm proteins are found in a second domain of life, the Archaea. These are the Sm1 and Sm2 proteins (not to be confused with the Sm1 and Sm2 sequence motifs), and are sometimes identified as Sm-like archaeal proteins SmAP1 and SmAP2 for this reason. Sm1 and Sm2 generally form homoheptamer rings, although homohexamer rings have been observed. Sm1 rings are similar to eukaryote Lsm rings in that they form in the absence of RNA while Sm2 rings are similar to eukaryote Sm rings in that they require uridine-rich RNA for their formation. They have been reported to associate with RNase P RNA, suggesting a role in transfer RNA processing, but their function in archaea in this process (and possibly processing other RNA such as ribosomal RNA) is mostly unknown. One of the two main branches of archaea, the crenarchaeotes have a third known type of archaeal LSm protein, Sm3. This is a two-domain protein with a N-terminal LSm domain that forms a homoheptamer ring. Nothing is known about the function of this LSm protein, but presumably it interacts with, and probably helps process, RNA in these organisms.
Bacterial LSm rings
Several LSm proteins have been reported in the third domain of life, the Bacteria. Hfq protein forms homohexamer rings, and was originally discovered as necessary for infection by the bacteriophage Qβ, although this is clearly not the native function of this protein in bacteria. It is not universally present in all bacteria, but has been found in Pseudomonadota, Bacillota, Spirochaetota, Thermotogota, Aquificota, and one species of Archaea. (This last instance is probably a case of horizontal gene transfer.) Hfq is pleiotropic with a variety of interactions, generally associated with translation regulation. These include blocking ribosome binding to mRNA, marking mRNA for degradation by binding to their poly-A tails, and association with bacterial small regulatory RNAs (such as DsrA RNA) that control translation by binding to certain mRNAs. A second bacterial LSm protein is YlxS (sometimes also called YhbC), which was first identified in the soil bacterium Bacillus subtilis. This is a two-domain protein with a N-terminal LSm domain. Its function is unknown, but amino acid sequence homologs are found in virtually every bacterial genome to date, and it may be an essential protein. The middle domain of the small conductance mechanosensitive channel MscS in Escherichia coli forms a homoheptameric ring. This LSm domain has no apparent RNA-binding function, but the homoheptameric torus is part of the central channel of this membrane protein.
Evolution and phylogeny
LSm homologs are found in all three domains of life, and may even be found in every single organism. Computational phylogenetic methods are used to infer phylogenetic relations. Sequence alignment between the various LSm homologs are the appropriate tool for this, such as multiple sequence alignment of the primary structure (amino acid sequence), and structural alignment of the tertiary structure (three-dimensional structure). It is hypothesized that a gene for a LSm protein was present in the last universal ancestor of all life. Based on the functions of known LSm proteins, this original LSm protein may have assisted ribozymes in the processing of RNA for synthesizing proteins as part of the RNA world hypothesis of early life. According to this view, this gene was passed from ancestor to descendant, with frequent mutations, gene duplications and occasional horizontal gene transfers. In principle, this process can be summarized in a phylogenetic tree with the root in the last universal ancestor (or earlier), and with the tips representing the universe of LSm genes existing today.
Homomeric LSm rings in bacteria and archaea
Based on structure, the known LSm proteins divide into a group consisting of the bacterial LSm proteins (Hfq, YlxS and MscS) and a second group of all other LSm proteins, in accordance with the most recently published phylogenetic trees. The three archaeal LSm proteins (Sm1, Sm2 and Sm3) also cluster as a group, distinct from the eukaryote LSm proteins. Both the bacterial and archaeal LSm proteins polymerize to homomeric rings, which is the ancestral condition.
Heteromeric LSm rings in eukaryotes
A series of gene duplications of a single eukaryote LSm gene resulted in most (if not all) of the known eukaryote LSm genes. Each of the seven Sm proteins has greater amino acid sequence homology to a corresponding Lsm protein than to the other Sm proteins. This suggests that an ancestral LSm gene duplicated several times, resulting in seven paralogs. These subsequently diverged from each other so that the ancestral homoheptamer LSm ring became a heteroheptamer ring. Based on the known functions of LSm proteins in eukaryotes and archaea, the ancestral function may have been processing of pre-ribosomal RNA, pre-transfer RNA, and pre-RNase P. Then, according to this hypothesis, the seven ancestral eukaryote LSm genes duplicated again to seven pairs of Sm/LSm paralogs; LSm1/SmB, LSm2/SmD1, LSm3/SmD2, LSm4/SmD3, LSm5/SmE, LSm6/SmF and LSm7/SmG. These two group of seven LSm genes (and the corresponding two kinds of LSm rings) evolved to an Sm ring (requiring RNA) and a Lsm ring (which forms without RNA). The LSm1/LSm8 paralog pair also seems to have originated prior to the last common eukaryote ancestor, for a total of at least 15 LSm protein genes. The SmD1/LSm10 paralog pair and the SmD2/LSm11 paralog pair exist only in animals, fungi, and the amoebozoa (sometimes identified as the unikont clade) and appears to be absent in the bikont clade (chromalveolates, excavates, plants and rhizaria). Therefore, these two gene duplications predated this fundamental split in the eukaryote lineage. The SmB/SmN paralog pair is seen only in the placental mammals, which dates this LSm gene duplication.
Biogenesis of snRNPs
Small nuclear ribonucleoproteins (snRNPs) assemble in a tightly orchestrated and regulated process that involves both the cell nucleus and cytoplasm.
References
External links
InterPro LSm entry
Protein families
Spliceosome | LSm | [
"Biology"
] | 5,973 | [
"Protein families",
"Protein classification"
] |
8,874,934 | https://en.wikipedia.org/wiki/CXCL13 | Chemokine (C-X-C motif) ligand 13 (CXCL13), also known as B lymphocyte chemoattractant (BLC) or B cell-attracting chemokine 1 (BCA-1), is a protein ligand that in humans is encoded by the CXCL13 gene.
Function
CXCL13 is a small chemokine belonging to the CXC chemokine family. As its other names suggest, this chemokine is selectively chemotactic for B cells belonging to both the B-1 and B-2 subsets, and elicits its effects by interacting with chemokine receptor CXCR5. CXCL13 and its receptor CXCR5 control the organization of B cells within follicles of lymphoid tissues and is expressed highly in the liver, spleen, lymph nodes, and gut of humans. The gene for CXCL13 is located on human chromosome 4 in a cluster of other CXC chemokines.
In T lymphocytes, CXCL13 expression is thought to reflect a germinal center origin of the T cell, particularly a subset of T cells called follicular B helper T cells (or TFH cells). Hence, expression of CXCL13 in T-cell lymphomas, such as angioimmunoblastic T-cell lymphoma, is thought to reflect a germinal center origin of the neoplastic T-cells.
References
External links
Cytokines | CXCL13 | [
"Chemistry"
] | 336 | [
"Cytokines",
"Signal transduction"
] |
8,875,134 | https://en.wikipedia.org/wiki/Meng%20Huo%20You | Meng Huo You () is the name given to petroleum in ancient China, which practiced the use of petroleum as an incendiary weapon in warfare.
Historical records of petroleum
During the Eastern Han dynasty, the Chinese historian and poet Ban Gu recorded in the geography section of his Book of Han that a flammable liquid substance are found in the Gao Nu County, located in the northeast portion of present-day Shaanxi Province. This "flammable liquid" was likely petroleum that had seeped through the ground and was floating above the local waters. Four hundred years later, during the late stages of Southern and Northern dynasties, historian Fan Ye cited in the Book of Later Han that the collection and exploitation of petroleum had been around for some time:
This "stone-lacquer" is likely petroleum. There are similar records from the Jin and Northern Wei dynasties as well.
The earliest mention of "rock oil" (石油), the Chinese name for petroleum, is by a book "Grand Peace Records" from the Northern Song dynasty, and officially designated the current name by Song dynasty polymath scientist Shen Kuo using the description found in his famous book Dream Pool Essays.
Due to the chemical characteristics of petroleum that it continues to burn in water, it was widely used by feudal militaries. Some examples include the defense of the city of Jiuquan in Gansu Province in the year 578 against the invading Göktürk army, in which the defenders used petroleum to ignite and destroy the siege engines brought in by the invaders.
Practice and proliferation of Meng Huo You
In ancient China, the use of petroleum in warfare was the most effective during the Five Dynasties and Ten Kingdoms period and the following four major dynasties and powers from Song through to Yuan, including the Jin and Liao dynasties. During this time a small dynasty in Vietnam paid tribute to the Chinese emperor with petroleum. Before this time, fire attacks were limited to burning wood or animal fat; using petroleum greatly increased the potency of fire attacks, and the fact that trying to douse the burning petroleum with water will only spread the fire more rapidly made burning oil an ideal weapon for destroying cities filled with wooden structures.
Meng Huo You is in many ways similar to the use of Greek fire. The devices used for the Chinese weapons had propelling systems as well. One of the key differences between the two weapons is the use of gunpowder as the ignition in the Chinese design.
Decline
The Chinese continued to use the oil as a way of repelling nomadic invaders from the northwest. However, by the Ming and Qing dynasties, the newly mature technology of gunpowder had for the most part replaced the use of these short-range flamethrowers, which saw little mention in the historical records of the last dynasties of imperial China.
External links
最早的火焰喷射器--猛火油柜 Chinese military museum's website illustrating the earliest flame throwers.
Flamethrowers
Chinese inventions
Military history of the Han dynasty
Medieval weapons
Petroleum
Weapons of China | Meng Huo You | [
"Chemistry"
] | 614 | [
"Petroleum",
"Chemical mixtures"
] |
8,875,183 | https://en.wikipedia.org/wiki/Kumadori | is the stage makeup worn by kabuki actors, mostly when performing kabuki plays in the style. The term also applies to a painting method in which two brushes are used simultaneously, one for the color and the other used to create shading or other details.
makeup generally consists of brightly coloured stripes or patterns over a white foundation, the colours and patterns symbolising aspects of the character. Though was originated and developed extensively by members of the family of actors, some conventions are creations of the line.
Colours
Only a few colours are used in makeup; red, blue, brown and black. Whilst black is simply used to exaggerate features, such as eyebrows and the line of the mouth, the other colours are used to tell the audience about the character's nature.
Red indicates a powerful hero role, often a character with virtue and courage. The most famous role to use red is that of the hero in , , and has come to stereotypically represent kabuki in the West.
Blue makeup is used to represent a villain, human or not, and represents negative emotions such as fear and jealousy. Ghosts in traditional Japanese dramas are often trapped by their attachment to such emotions, and so often wear blue makeup; (fox spirits) such as in wear blue makeup as well.
Brown represents monsters and non-human spirits, such as (demons). One example of the usage of brown is the (ground spider) fought by in .
Patterns
Though only four colours are used, there are over 50 different patterns of . is worn symmetrically on both sides. Some patterns are used for a number of roles, as they have come to represent a specific type of character over time, regardless of the play being performed:
- this style of features two red lines leading up into the hairline, one leading off the eyebrows and one leading off the eyeline. This pattern is used to express quiet strength in heroes.
- the most well-known pattern of red , as seen in on the hero . Its dramatic red lines represent the power and righteous anger of the character.
- a stylish form of red used for young, handsome and virtuous heroes. The character of in wears , and is the epitome of a handsome kabuki hero attempting to win the love of a high-ranking courtesan.
- the style of used for comic villains; though the is red, the lines used make the character look like an animal, indicating that they should not be taken seriously. Some forms of make the character look like a monkey, or a crab.
- a dramatic form of blue used to indicate a villainous imperial court aristocrat looking to overthrow those in power. The design used is very similar to that of .
An impression of a kabuki actor's face make-up, preserved on a piece of cloth, is known as an .
References
Kabuki
Costume design
Makeup
Cultural history of Japan
Japanese fashion | Kumadori | [
"Engineering"
] | 593 | [
"Costume design",
"Design"
] |
8,875,186 | https://en.wikipedia.org/wiki/Moyal%20bracket | In physics, the Moyal bracket is the suitably normalized antisymmetrization of the phase-space star product.
The Moyal bracket was developed in about 1940 by José Enrique Moyal, but Moyal only succeeded in publishing his work in 1949 after a lengthy dispute with Paul Dirac. In the meantime this idea was independently introduced in 1946 by Hip Groenewold.
Overview
The Moyal bracket is a way of describing the commutator of observables in the phase space formulation of quantum mechanics when these observables are described as functions on phase space. It relies on schemes for identifying functions on phase space with quantum observables, the most famous of these schemes being the Wigner–Weyl transform. It underlies Moyal’s dynamical equation, an equivalent formulation of Heisenberg’s quantum equation of motion, thereby providing the quantum generalization of Hamilton’s equations.
Mathematically, it is a deformation of the phase-space Poisson bracket (essentially an extension of it), the deformation parameter being the reduced Planck constant . Thus, its group contraction yields the Poisson bracket Lie algebra.
Up to formal equivalence, the Moyal Bracket is the unique one-parameter Lie-algebraic deformation of the Poisson bracket. Its algebraic isomorphism to the algebra of commutators bypasses the negative result of the Groenewold–van Hove theorem, which precludes such an isomorphism for the Poisson bracket, a question implicitly raised by Dirac in his 1926 doctoral thesis, the "method of classical analogy" for quantization.
For instance, in a two-dimensional flat phase space, and for the Weyl-map correspondence, the Moyal bracket reads,
where ★ is the star-product operator in phase space (cf. Moyal product), while and are differentiable phase-space functions, and is their Poisson bracket.
More specifically, in operational calculus language, this equals
The left & right arrows over the partial derivatives denote the left & right partial derivatives. Sometimes the Moyal bracket is referred to as the Sine bracket.
A popular (Fourier) integral representation for it, introduced by George Baker is
Each correspondence map from phase space to Hilbert space induces a characteristic "Moyal" bracket (such as the one illustrated here for the Weyl map). All such Moyal brackets are formally equivalent among themselves, in accordance with a systematic theory.
The Moyal bracket specifies the eponymous infinite-dimensional
Lie algebra—it is antisymmetric in its arguments and , and satisfies the Jacobi identity.
The corresponding abstract Lie algebra is realized by ★, so that
On a 2-torus phase space, , with periodic
coordinates and , each in , and integer mode indices , for basis functions , this Lie algebra reads,
which reduces to SU(N) for integer .
SU(N) then emerges as a deformation of SU(∞), with deformation parameter 1/N.
Generalization of the Moyal bracket for quantum systems with second-class constraints involves an operation on equivalence classes of functions in phase space, which can be considered as a quantum deformation of the Dirac bracket.
Sine bracket and cosine bracket
Next to the sine bracket discussed, Groenewold further introduced the cosine bracket, elaborated by Baker,
Here, again, ★ is the star-product operator in phase space, and are differentiable phase-space functions, and is the ordinary product.
The sine and cosine brackets are, respectively, the results of antisymmetrizing and symmetrizing the star product. Thus, as the sine bracket is the Wigner map of the commutator, the cosine bracket is the Wigner image of the anticommutator in standard quantum mechanics. Similarly, as the Moyal bracket equals the Poisson bracket up to higher orders of , the cosine bracket equals the ordinary product up to higher orders of . In the classical limit, the Moyal bracket helps reduction to the Liouville equation (formulated in terms of the Poisson bracket), as the cosine bracket leads to the classical Hamilton–Jacobi equation.
The sine and cosine bracket also stand in relation to equations of a purely algebraic description of quantum mechanics.
References
Mathematical quantization
Symplectic geometry | Moyal bracket | [
"Physics"
] | 888 | [
"Mathematical quantization",
"Quantum mechanics"
] |
8,875,517 | https://en.wikipedia.org/wiki/Chroogomphus%20vinicolor | Chroogomphus vinicolor, commonly known as the wine-cap Chroogomphus or the pine spike, is a species of mushroom in the family Gomphidiaceae. Found in North America and the Dominican Republic, mushrooms grow on the ground under pine trees. Fruit bodies have reddish-brown, shiny caps atop tapered stems. The gills are thick, initially pale orange before turning blackish, and extend a short way down the length of the stem. Although the mushroom is edible, and sold in local markets in Mexico, it is not highly rated. Distinguishing this species from some other similar Chroogomphus species is difficult, as their morphology is similar, and cap coloration is too variable to be a reliable characteristic. C. vinicolor is differentiated from the European C. rutilus and the North American C. ochraceus by the thickness of its cystidial walls.
Taxonomy
The species was first described as Gomphidius vinicolor in 1898 by American mycologist Charles Horton Peck, based on specimens collected near Lake Mohonk in Ulster County, New York. Peck noted a resemblance to Gomphidius roseus, which he thought was closely related. It was transferred to the newly created genus Chroogomphus by Orson K. Miller, Jr. in 1964.
Molecular analysis of internal transcribed spacer DNA sequences shows that C. vinicolor groups in a clade with the closely related C. jamaicensis and C. pseudovinicolor. All of these species feature darkly-amyloid flesh and thick-walled cystidia. Based on this analysis, Miller considered C. jamaicensis to be insufficiently distinct genetically from C. vinicolor to warrant designation as a separate species; however, as of 2012, both MycoBank and Index Fungorum list it as a valid species.
The specific epithet vinicolor means "wine-colored". It is commonly known as the "wine-cap Chroogomphus" or the "pine spike".
Description
The fruit body of C. vinicolor has caps that are initially conical to convex before later flattening out, sometimes developing a small umbo, or a central depression; the caps measure wide. Its color is highly variable, ranging from wine-red to reddish-brown to orange-brown or yellow-brown. Wine-red stains develop where the surface has dried or become rotten. The smooth cap surface is shiny, somewhat sticky when wet, and often radially streaked. The flesh is thick and orangish to ochraceous in color; its taste and odor have been variously described as "not distinctive" or "pleasant". The thick gills are decurrent (attached to and extending a short ways down the stem), well spaced, ochraceous buff to pale orange when young, but turning to blackish after the spores mature. In his original description, Peck noted that the gills, when viewed with a hand lens, "appear velvety due to the abundant spores". The fruit bodies are initially covered with a thin, web-like partial veil that soon disappears as the cap expands. The cylindrical stem measures long by thick, and taper towards the base. It is ochraceous to wine red or reddish-brown with a dry, smooth to fibrillose surface. The partial veil sometimes leaves an indistinct, thin fibrous ring on the upper stem.
The spore print is greyish-black. The spores are narrowly elliptical to spindle-shaped, smooth, and measure 17–23 by 4.5–7.5 μm. The cystidia are somewhat spindle-shaped or narrowly club-shaped, and measure 112–164 by 13–20 μm. They have characteristically thick walls, up to 7.5 μm wide in the middle portion.
Although the mushroom is edible, and is often free of insect damage, it is not highly recommended, "except as "fillers" to include with the more flavorful species". The flavor may improve with drying. C. vinicolor mushrooms are sold in local markets at Tetela del Volcan in the state of Morelos, Mexico. There is a report of this species causing a contact sensitivity, in which an individual who had handled the mushroom developed a burning sensation in the eyes and an itchy rash on the eyelid after rubbing the eyes.
Similar species
Two other Chroogomphus species with a morphology and coloration similar to C. vinicolor include C. rutilus and C. ochraceous. C. vinicolor is most reliably distinguished from these on the basis of having thick-walled cystidia (up to 5–7.5 μm at the widest part). The other two species have been separated on the basis of color, with C. ochraceous having brighter colors (yellowish-orange to ochraceous) than C. rutilus. Molecular analyses of European and North American collections suggest that C. rutilus is restricted to Europe, C. ochraceous only occurs in North America, and that cap coloration cannot be reliably used for species determination.
Another nearly identical species is C. jamaicensis, found in the Dominican Republic, Jamaica, and the Greater Antilles. It is distinguished microscopically by its slightly smaller spores measuring 17–20 by 4.5–6 μm, cystidia with more uniformly thickened walls up to 5 μm thick, and cuticular hyphae that measure 2–5 μm wide. The fruit bodies of C. pseudovinicolor are more robust, with wooly or scaly reddish stems up to thick. Further, this species tends to produce spore prints that are greener than those of C. vinicolor. Another similar-looking species is C. tomentosus.
Some toxic Cortinarius species are similar in appearance, but can be recognized by their rusty brown spores.
Habitat and distribution
The mycorrhizal fungus sometimes fruits singly, but more often in scattered or groups on the ground under pines and other conifers. Fruiting usually occurs in the cooler weather of later summer and autumn. In coastal California, however, fruiting occurs in winter. It is often found near Suillus luteus and Suillus brevipes, and is known to parasitize the mycelium of both those and the truffle-like Rhizopogon species. Chroogomphus vinicolor has a widespread range in North America, extending south to Mexico. It has also been recorded from the Dominican Republic.
References
Edible fungi
Boletales
Fungi described in 1964
Fungi of North America
Fungi of the Caribbean
Fungus species | Chroogomphus vinicolor | [
"Biology"
] | 1,375 | [
"Fungi",
"Fungus species"
] |
16,279,113 | https://en.wikipedia.org/wiki/Fleischmann%27s%20Yeast | Fleischmann's Yeast is an American brand of yeast founded by Hungarian-American businessman Charles Louis Fleischmann. It is currently owned by Associated British Foods and is sold to both consumer and industrial markets in the United States and Canada.
The yeast is available in a number of different forms with various qualities and intended uses. Fleischmann's is also a brand name of corn oil margarine.
History
The company was founded by Hungarian Jews Charles Louis Fleischmann, his brother Maximilian, and James Gaff in Riverside, Cincinnati, in 1868, as Gaff, Fleischmann & Company. They exhibited their yeast at the 1876 Centennial Exposition. After Gaff's death in 1881, the name was changed to Fleischmann and Company, and then The Fleischmann Company in 1905.
In 1924, the brothers' nephew Raoul Fleischmann, using the wealth generated by the family business, provided the funding for the launch of The New Yorker with his friend Harold Ross. Raoul invested $700,000 before the magazine became profitable, and he was the magazine's publisher until his death in 1969.
In 1929, the company was merged into Standard Brands by J.P. Morgan, and that same year the company began the sponsorship of the musical variety radio program, The Fleischmann's Yeast Hour starring Rudy Vallée.
In the 1930s, the company's advertisements highlighted "intestinal fatigue", a condition said to be brought on by the pressures of modern civilization. The ads claimed that Fleischmann's Yeast was an effective treatment for the condition, despite protests by the American Medical Association. In 1936, Consumer Reports disputed Fleischmann Yeast's advertising claims that it cured constipation and acne.
Standard Brands merged with Nabisco Brands, Inc. in 1981.
In 1986, RJR Nabisco sold Fleischmann's to the Australian company Burns Philp for $130 million.
Burns Philp sold its yeast business to Associated British Foods in 2004 for US$1.4 billion.
During the 2020 COVID-19 pandemic in March and for subsequent months, Fleischmann's struggled to meet surging demand for its products, as house-bound consumers sought to produce more of their own baked goods. The company faced shortages of raw materials and the lengthy process of yeast production limited production.
Products
Common forms of yeast Fleischmann's make are: (i) cubes or "cakes" of compressed fresh yeast wrapped in foil, an original form of packaged yeast that is soft and perishable; (ii) packets of Active Dry Yeast, a shelf stable granular yeast invented by Fleischmann during World War II; (iii) packets of RapidRise yeast intended to reduce dough rising time by as much as 50% by bypassing the first rise; (iv) bread machine yeast, an instant yeast sold in a glass jar; and (v) pizza crust yeast, an instant yeast packaged with enzymes and dough relaxers such as L-Cysteine intended to add pliability to dough and reduce the amount of time needed to make a fresh pizza crust.
Fleischmann's Active Dry Yeast is the best-known of their yeast products due to its extended shelf life compared to fresh yeast.
Presidents
Charles Louis Fleischmann, 1868 through 1897
Julius Fleischmann, 1897 through 1925
Maximilian C. Fleischmann, 1925 through 1929
See also
Fleischmann's Vodka
Fleischmanns, New York
References
External links
Official website (consumers)
Official website (industrial)
Official website (holding company)
Food additives
Leavening agents
Food product brands
Yeasts
Associated British Foods brands
Nabisco brands
American brands
Manufacturing companies based in Cincinnati | Fleischmann's Yeast | [
"Biology"
] | 775 | [
"Yeasts",
"Fungi"
] |
16,279,945 | https://en.wikipedia.org/wiki/Gould%E2%80%93Jacobs%20reaction | The Gould–Jacobs reaction is an organic synthesis for the preparation of quinolines and 4‐hydroxyquinoline derivatives. The Gould–Jacobs reaction is a series of reactions. The series of reactions begins with the condensation/substitution of an aniline with alkoxy methylenemalonic ester or acyl malonic ester, producing anilidomethylenemalonic ester. Then through a 6 electron cyclization process, 4-hydroxy-3-carboalkoxyquinoline is formed, which exist mostly in the 4-oxo form. Saponification results in the formation of an acid. This step is followed by decarboxylation to give 4-hydroxyquinoline. The Gould–Jacobs reaction is effective for anilines with electron‐donating groups at the meta‐position.
Specifically, 4-quinolinol can be synthesized. In this reaction aniline or an aniline derivative first reacts with malonic acid derivative ethyl ethoxymethylenemalonate with substitution of the ethoxy group by nitrogen. A benzannulation takes place by application of heat to a quinoline. The ester group is hydrolysed by sodium hydroxide to the carboxylic acid and decarboxylation again by application of heat to 4-hydroxyquinoline.
Extension of the Gould-Jacobs approach can prepare unsubstituted parent heterocycles with fused pyridine ring of Skraup type (see Skraup reaction).
Further reading:
Mechanism
The mechanism for the Gould–Jacobs reaction begins with a nucleophilic attack from the amine nitrogen follows by the loss of ethanol to form the condensation product. A 6 electron cyclization reaction with the loss of another ethanol molecule forms a quinoline (ethyl 4-oxo-4,4a-dihydroquinoline-3-carboxylate). The enol form can be represented from the keto form through keto-enol tautomerism. Protonation of the nitrogen forms ethyl 4-oxo-1,4-dihydroquinoline-3-carboxylate.
Examples and applications
An example is the synthesis of 4,7-dichloroquinoline.
Floctafenine and glafenine are a pair of fenamate NSAIDs whose syntheses rely on the Gould–Jacobs reaction.
Several quinolone antibiotic structures such as rosoxacin, oxolinic acid, droxacin, etc.
Another example is in the synthesis of antimalarials as aminoalkylamino derivatives of 2,3-dihydrofuroquinolines
The Gould reaction is also used to convert 5-aminoindole to quinolines for the purpose of synthesizing pyrazolo[4,3-c]pyrrolo[3,2-f]quinolin-3-one derivatives as modified pyrazoloquinolinone analogs. These compounds have the potential to act as antagonists at central benzodiazepine receptors (BZRs) in Xenopus laevis oocytes.
The Gould‐Jacobs reaction has also been used both conventionally with condensation steps and acyclic intermediated and with single step microwave irradiation to synthesize ethyl 4‐oxo‐8,10‐substituted‐4,8‐dihydropyrimido[1,2‐c]pyrrolo[3,2‐e]pyrimidine‐3‐carboxylates.
References
Quinoline forming reactions
Name reactions | Gould–Jacobs reaction | [
"Chemistry"
] | 767 | [
"Name reactions"
] |
16,280,210 | https://en.wikipedia.org/wiki/HD%203346 | HD 3346, also known as V428 Andromedae, is a binary star system in the northern constellation of Andromeda. It is a dim star but visible to the naked eye under suitable viewing conditions, having an apparent visual magnitude of 5.14. The distance to HD 3346 can be determined from its annual parallax shift of . This yields a range of about . At that distance the brightness of the system is diminished by an extinction of 0.16 magnitude due to interstellar dust. It is moving closer to the Earth with a heliocentric radial velocity of −33 km/s.
Binary system
This is a single-lined spectroscopic binary system with an orbital period of 576 days and an eccentricity of 0.3. The a sin i value for the primary is , where a is the semimajor axis and i is the (unknown) orbital inclination. The provides a minimum value for the actual semimajor axis.
The visible component is a red giant star and has been defined as a standard star for the stellar classification of K6 IIIa. Prior to that there had been no spectral standard for K6 giants and HD 3346 had been classified between K5 III and M0 III.
In 1996 it was announced that the variations in radial velocity of this star were larger than expected. Two orbiting companions were proposed to explain this variation, the one known since 1985 with a period of about 650 days and a minimum mass of about , and a second one with a period of about 14-40 days and a minimum mass of about . The existence of this second, possibly planetary companion was never confirmed.
Variability
In 1982, HD 3346 was listed as a suspected variable star (NSV 15135) in Pavel Nikolaevich Kholopov's catalog of suspected variable stars. Gregory W. Henry et al. confirmed that the star is variable in year 2000. It was given its variable star designation, V428 Andromedae, in 2003.
It is a short-period semi-regular variable (type SRS), also called an ultra-small-amplitude pulsating red giant. It has an amplitude of only 0.065 magnitudes. The main pulsation period is 11.5 days, but other periods of 11, 15, and 22 days have been detected.
References
External links
K-type giants
Short period semiregular variable
Hypothetical planetary systems
Andromeda (constellation)
BD+43 0113
003346
002900
0152
Andromedae, V428
Spectroscopic binaries | HD 3346 | [
"Astronomy"
] | 528 | [
"Andromeda (constellation)",
"Constellations"
] |
16,280,255 | https://en.wikipedia.org/wiki/Radio%20relay | Radio stations that cannot communicate directly due to distance, terrain or other difficulties sometimes use an intermediate radio relay station to relay the signals. A radio relay receives weak signals and retransmits them, often in a different direction, as a stronger signal. Examples include airborne radio relay, microwave radio relay, and communications satellite. The American Radio Relay League was founded for this purpose but did not change its name when this became a less important part of its work.
See also
Repeater
Transponder
Broadcast relay station
Radio communications | Radio relay | [
"Engineering"
] | 106 | [
"Telecommunications engineering",
"Radio communications"
] |
16,280,461 | https://en.wikipedia.org/wiki/Social%20nature | Social Nature is the core concept of a geographical work on the social construction of nature, entitled Social nature: theory, practice and politics, which was published by Noel Castree and Bruce Braun in 2001.
The book says that the concept of Social Nature was created by critical geographers and embraces the idea of a socialized nature. Critical geographers like David Harvey and Neil Smith "insisted that nature is social in three related ways":
Knowledge "of nature is invariably inflected with the biases of the" knowers,
"Though knowledges of nature are social through and through, the social dimensions of nature are not reducible to knowledge alone",
Societies "physically reconstitute nature, both intentionally and unintentionally", to the point of internalizing nature into social processes (particularly in advanced Western societies).
References
Human geography
Social constructionism | Social nature | [
"Environmental_science"
] | 179 | [
"Environmental social science stubs",
"Environmental social science",
"Human geography"
] |
16,280,475 | https://en.wikipedia.org/wiki/Dyfi%20Furnace | Dyfi Furnace is a restored mid 18th century charcoal fired blast furnace used for smelting iron ore. It has given its name to the adjoining hamlet of Furnace ().
Location
The Dyfi Furnace is in the village of Furnace, Ceredigion, Wales, adjoining the A487 trunk road from Machynlleth to Aberystwyth, near Eglwysfach.
History
The site for Dyfi Furnace was chosen downstream of the waterfall on the River Einion to take advantage of the water power from the river and charcoal produced from the local woodlands, with the iron ore being shipped in from Cumbria via the Afon Dyfi.
The furnace built around 1755 was only used for about fifty years to smelt iron ore. By 1810 it had been abandoned and the waterwheel removed.
The etching by John George Wood to accompany his "The Principal Rivers of Wales", published 1813, shows the furnace in its transitional form with no waterwheel attached. Some time later a new waterwheel was installed - the one that has been renovated and is visible today - and the furnace became a sawmill. The furnace site was renovated around 1988.
The furnace was built by Ralph Vernon and the brothers Edward Bridge and William Bridge . Vernon retired between 1765 and 1770, and the Bridges (who also owned Conwy Furnace) became bankrupt in 1773. It is likely that the furnace was then transferred to Kendall & Co. (Jonathan Kendall and his brother Henry), ironmasters from the West Midlands with extensive interests scattered across Staffordshire, Cheshire, The Lake District and Scotland. After the original lease expired in 1796, it appears the furnace was then owned by Bell and Gaskell, including Thomas Bell, who had managed it for the Kendalls, whose main activity by then was running the Beaufort Ironworks in Beaufort, Ebbw Vale, in the South Wales Valleys.
The water wheel, shown in the photographs, provided power for a sawmill.
The site was previously a Silver Mill of the Society of Mines Royal.
See also
Harrison Ainslie
References
James Dinn, 'Dyfi Furnace excavations 1982-87', Post-medieval Archaeology 22 (1988), 111-42.
External links
www.geograph.co.uk : photos of Dyfi Furnace and surrounding area
Visitor information
CADW page
Industrial history of Wales
Ironworks and steelworks in Wales
History of Ceredigion
Furnaces
Grade II* listed buildings in Ceredigion | Dyfi Furnace | [
"Engineering"
] | 498 | [
"Furnaces",
"Combustion engineering"
] |
16,281,330 | https://en.wikipedia.org/wiki/Laser%20spray%20ionization | Laser spray ionization refers to one of several methods for creating ions using a laser interacting with a spray of neutral particles or ablating material to create a plume of charged particles. The ions thus formed can be separated by m/z with mass spectrometry. Laser spray is one of several ion sources that can be coupled with liquid chromatography-mass spectrometry for the detection of larger molecules.
Types of laser spray ionization
Neutral spray
In one version of the laser spray interface, explosive vaporization and mist formation occur when an aqueous solution effusing from the tip of the stainless steel capillary is irradiated from the opposite side of the capillary by a 10.6 μm infrared laser. Weak ion signals could be detected when the plume was sampled through the ion sampling orifice. When a high voltage (3–4 kV) was applied to the stainless-steel capillary, strong ion signals appeared. The ion abundances were found to be orders of magnitude greater than those obtained by conventional electrospray ionization in the case of aqueous solutions. This approach to laser spray ionization is a hybrid of three basic techniques for the generation of gaseous ions from the condensed phase, i.e., energy-sudden activation, nebulization and the action of an electric field.
Laser spray mass spectrometry can faithfully reflect the solution-phase characteristics of biomolecules. It has been successfully applied to evaluate the binding affinities of protein-DNA.
Laser spray has better ionization efficiency than conventional electrospray ionization (ESI). In particular, the sensitivity became more than one order of magnitude higher in negative ion modes. It was also found that this technique has a potential benefit for the low concentration samples due to condensation effect of the formed droplet by the irradiation of laser. Higher the solvation energies of triply charged metal ions, stronger are the signals for ions.
Laserspray ionization
Laserspray Ionization (LSI) is a newer mass spectrometric technique commonly used with biomolecules, such as proteins. This method is similar to matrix-assisted laser desorption/ionization (MALDI) at atmospheric pressure in that it involves an analyte and matrix mixture. It also contains features from electrospray ionization, in which it produces a similar mass spectra. The mechanism was initially thought to involve laser induced production of highly charge matrix/analyte clusters that upon evaporation of the matrix produces ions by the same mechanism as ESI. LSI's ability to ablate proteins at atmospheric pressure in order to form a multiple of charged ions with a mass resolution of 100,000 when coupled with a quadrupole orbitrap mass spectrometer. The advantages of using LSI includes a solvent-free ionization technique, fast data acquisition, simply to use, and the improved fragmentation through multiple charging.
Laser spray inlet ionization
Due to recent innovations to the laser spray technique, a new method of laser ablation using the spray method has surfaced. Laserspray inlet ionization (LSII) involves a matrix/analyte sample at atmospheric pressure being ablated, and the ionization process will take place in an ion transfer capillary tube located in the mass spectrometer inlet. The LSII method is also known as laserspray ionization vacuum (LSIV).
Applications
Matrix-assisted inlet ionization (MAII) has shown that the laser is not necessary for the ionization process. Ions are formed when matrix-analyte is introduced to the vacuum of a mass spectrometer through an inlet aperture. LSI is a subset of MAII and is now called laserspray inlet ionization (LSII). Laser spray inlet ionization and matrix-assisted inlet ionization can be coupled to a fourier transform ion cyclotron resonance (FT-ICR) mass analyzer to improve detection of peptides and proteins.
References
Chromatography
Ion source | Laser spray ionization | [
"Physics",
"Chemistry"
] | 828 | [
"Chromatography",
"Spectrum (physical sciences)",
"Separation processes",
"Ion source",
"Mass spectrometry"
] |
16,281,733 | https://en.wikipedia.org/wiki/Talis%20Group | Talis Group Ltd. is a software company based in Birmingham, England that develops software for higher education. They were previously involved in development of library management software and a Semantic Web application platform. In 2005 Talis was voted one of the top ICT Employers in the United Kingdom.
History
In 1969 a number of libraries founded a small co-operative project, based in Birmingham, to provide services that would help the libraries become more efficient. The project was known as the Birmingham Libraries Co-operative Mechanisation Project, or BLCMP, and included the library of the University of Birmingham. At this time the concept of library automation was so new that the term mechanisation was often used in its place.
BLCMP began a co-operative catalogue of bibliographic data at the start of its work, a database that now contains many millions of records. For this an adaptation of UKMARC coding was used. This shared approach to creating metadata is the forefather of later, Internet-based, community ventures such as IMDb, Freebase and others. But this was back in 1969 when shipping this data around involved printing cards and putting boxes on trucks. More libraries became members of BLCMP, e.g. many of the academic libraries of Manchester and Salford.
BLCMP moved into using microfiche and later IBM mainframes with dedicated terminals at libraries in the mid-seventies and was one of the first library automation vendors to provide a GUI on top of Microsoft Windows to provide a better interface for end-users. The integrated library system (ILS) was first called Talis after 'The Automated Library And Information System'. Talis became the name of the company during re-structuring and the ILS became known as Alto. In 1995 Talis was the first library systems vendor to produce a web-enabled public access catalogue. The library of the University of Sheffield became the 50th customer to choose the Talis library system in 1996.
During the first decade of the 3rd millennium, much of Talis's work focused on the transition of information to the web, specifically the Semantic Web, and Talis has led much of the debate about how Web 2.0 attitudes affect traditional libraries. Alongside semantic web developments Talis launched Talis Education Ltd, a business focused on products in Higher Education learning, and Kasabi, a data marketplace.
In March 2011 Talis sold its library management division to Capita Group. The division was sold for a reported £18.5 million plus a further £2.5 million depending on the company's profitability in the following financial year. The company moved its headquarters from Solihull to central Birmingham.
Following the sale of its library management business Talis experimented with a semantic web and data marketplace business alongside the rapidly establishing education business. A tough economic climate required Talis to focus its investment, therefore they announced in July 2012 that investment in the semantic web and data marketplace areas would cease. All efforts are now concentrated on the education business.
Talis Aspire, the company's enterprise teaching and learning platform, is now in use by over 1 million students at 93 universities across 8 countries, including over 65% of all UK universities.
Talis was acquired by SAGE Publications in 2018.
As of 2023, Talis Aspire has effectively become the global market leader in reading list software.
See also
Copac
Library 2.0
SUNCAT
References
Further reading
Stubley, P. (1988). BLCMP: a guide for librarians and systems managers. Aldershot, Hants, England: Gower.
Birmingham; Buckle, David, & BLCMP. (1974). Birmingham libraries co-operative mechanisation project: research and development programme, January 1969 to March 1975 : a background paper.
Birmingham Libraries Co-operative Mechanisation Project, & Buckle, D. G. R. (1976). Birmingham Libraries Co-operative Mechanisation Project final report. Birmingham: BLCMP. (David Buckle became the first manager of BLCMP.)
External links
Talis Group Ltd.—company homepage
Companies based in Birmingham, West Midlands
Semantic Web companies
Software companies of the United Kingdom
Library automation
Library cataloging and classification
Library-related organizations
Software companies established in 1969
1969 establishments in England
Employee-owned companies of the United Kingdom
British companies established in 1969
Science and technology in the West Midlands (county) | Talis Group | [
"Engineering"
] | 891 | [
"Library automation",
"Automation"
] |
16,282,158 | https://en.wikipedia.org/wiki/Restrictive%20design%20rules | Design rules are maintained and released by a semiconductor foundry for its customers (layout designers of integrated circuits) to follow. Restrictive design rules (RDRs) curtail some of the "freedom" layout designers have traditionally had with regular design rules in less advanced process technologies. To achieve and maintain an acceptable return on investment for its customers and by extension for itself, a foundry may be compelled, for technological reasons, to adopt RDRs to better ensure the completed layout design of an integrated circuit is manufacturable with a desired yield in more advanced process technologies.
External links
Gartner's Smith calls for 'restrictive design rules' at 32-nm
Beyond DFM: battle lines forming over restrictive design rules ()
'Restrictive design rules' at 32-nm technology
Semiconductor device fabrication | Restrictive design rules | [
"Materials_science",
"Technology"
] | 158 | [
"Semiconductor device fabrication",
"Computing stubs",
"Microtechnology",
"Computer hardware stubs"
] |
16,284,001 | https://en.wikipedia.org/wiki/Signed%20overpunch | In computing, a signed overpunch is a coding scheme which stores the sign of a number by changing (usually) the last digit. It is used in character data on IBM mainframes by languages such as COBOL, PL/I, and RPG. Its purpose is to save a character that would otherwise be used by the sign digit. The code is derived from the Hollerith Punched Card Code, where both a digit and a sign can be entered in the same card column. It is called an overpunch because the digit in that column has a 12-punch or an 11-punch above it to indicate the sign. The top three rows of the card are called zone punches, and so numeric character data which may contain overpunches is called zoned decimal.
In IBM terminology, the low-order four bits of a byte in storage are called the digit, and the high-order four bits are the zone. The digit bits contain the numeric value 0–9. The zone bits contain either 'F'x, forming the characters 0–9, or the character position containing the overpunch contains a hexadecimal value indicating a positive or negative value, forming a different set of characters. (A, C, E, and F zones indicate positive values, B and D negative).
The PACK instruction on IBM System/360 architecture machines converts the sign of a zoned decimal number when converting to packed decimal,
and the corresponding UNPK instruction will set the correct overpunched sign of its zoned decimal output.
Language support
PL/I
PL/I uses the PICTURE attribute to declare zoned decimal data with a signed overpunch. Each character in a numeric picture except V, which indicates the position of the assumed decimal point, represents a digit. A picture character of T, I, or R indicates a digit position which may contain an overpunch. T indicates that the position will contain {–I if positive and {–R if negative. I indicates that the position will contain {–I if positive and 0-9 if negative. R indicates that the position will contain 0–9 if positive and {–R if negative.
For example PICTURE 'Z99R' describes a four-character numeric field. The first position may be blank or will contain a digit 0–9. The next two positions will contain digits, and the fourth position will contain 0–9 for a positive number and {–R for negative.
Assigning the value 1021 to the above picture will store the characters "1021" in memory; assigning -1021 will store "102J".
COBOL
COBOL uses the picture character 'S' for USAGE IS DISPLAY data without SIGN IS SEPARATE CHARACTER to indicate an overpunch. SIGN IS LEADING indicates that the overpunch is over the first character of the field. SIGN IS TRAILING, locates it over the last character. SIGN IS TRAILING is the default.
C/C++
The C language has no provision for zoned decimal. The IBM ILE C/C++ compiler for System i provides functions for conversion between int or double and zoned decimal:
QXXDTOZ() — Convert Double to Zoned Decimal
QXXITOZ() — Convert Integer to Zoned Decimal
QXXZTOD() — Convert Zoned Decimal to Double
QXXZTOI() — Convert Zoned Decimal to Integer
EBCDIC overpunch codes
Examples
10} is -100
45A is 451
ASCII representation
Representation of signed overpunch characters "is not standardized in ASCII, and different compilers use different overpunch codes." In some cases, "the representation is not the same as the result of converting an EBCDIC Signed field to ASCII with a translation table." In other cases they are the same, to maintain source-data compatibility at the loss of the connection between the character code and the corresponding digit.
An EBCDIC negative field ending with the digit '1' will encode that digit as 'D1'x, upper-case 'J', where the digit is '1' and the zone is 'D' to indicate a negative field. ASCII upper-case 'J' is '4A'x, where the hexadecimal value bears no relationship to the numeric value. An alternative encoding uses lower-case 'q', '71'x, for this representation, where the digit is '1' and the zone is '7'. This preserves the digit and the collating sequence at the cost of having to recognize and translate fields with overpunches individually.
Examples
Gnu COBOL and MicroFocus COBOL use lower-case 'p' thru 'y' to represent negative '0' thru '9'.
PL/I compilers on ASCII systems use the same set of characters ({, J–R) as EBCDIC to represent overpunches.
References
Computer programming
Punched card
Computer data
History of software | Signed overpunch | [
"Technology",
"Engineering"
] | 1,033 | [
"Computer programming",
"Computer data",
"Software engineering",
"History of software",
"Data",
"Computers",
"History of computing"
] |
16,285,128 | https://en.wikipedia.org/wiki/Metal%E2%80%93ligand%20multiple%20bond | In organometallic chemistry, a metal–ligand multiple bond describes the interaction of certain ligands with a metal with a bond order greater than one. Coordination complexes featuring multiply bonded ligands are of both scholarly and practical interest. transition metal carbene complexes catalyze the olefin metathesis reaction. Metal oxo intermediates are pervasive in oxidation catalysis.
As a cautionary note, the classification of a metal–ligand bond as being "multiple" bond order is ambiguous and even arbitrary because bond order is a formalism. Furthermore, the usage of multiple bonding is not uniform. Symmetry arguments suggest that most ligands engage metals via multiple bonds. The term 'metal–ligand multiple bond" is often reserved for ligands of the type and (n = 0, 1, 2) and (n = 0, 1) where R is H or an organic substituent, or pseudohalide. Historically, and are not included in this classification, nor are halides.
Pi-donor ligands
In coordination chemistry, a pi-donor ligand is a kind of ligand endowed with filled non-bonding orbitals that overlap with metal-based orbitals. Their interaction is complementary to the behavior of pi-acceptor ligands. The existence of terminal oxo ligands for the early transition metals is one consequence of this kind of bonding. Classic pi-donor ligands are oxide (O2−), nitride (N3−), imide (RN2−), alkoxide (RO−), amide (R2N−), and fluoride. For late transition metals, strong pi-donors form anti-bonding interactions with the filled d-levels, with consequences for spin state, redox potentials, and ligand exchange rates. Pi-donor ligands are low in the spectrochemical series.
Multiple bond stabilization
Metals bound to so-called triply bonded carbyne, imide, nitride (nitrido), and oxide (oxo) ligands are generally assigned to high oxidation states with low d electron counts. The high oxidation state stabilizes the highly reduced ligands. The low d electron count allow for many bonds between ligands and the metal center. A d0 metal center can accommodate up to 9 bonds without violating the 18 electron rule, whereas a d6 species can only accommodate 6 bonds.
Reactivity explained through ligand hybridization
A ligand described in ionic terms can bond to a metal through however many lone pairs it has available. For example, many alkoxides use one of their three lone pairs to make a single bond to a metal center. In this situation the oxygen is sp3 hybridized according to valence bond theory. Increasing the bond order to two by involving another lone pair changes the hybridization at the oxygen to an sp2 center with an expected expansion in the M-O-R bond angle and contraction in the M-O bond length. If all three lone pairs are included for a bond order of three than the M-O bond distance contracts further and since the oxygen is a sp center the M-O-R bond angle is 180˚ or linear. Similarly with the imidos are commonly referred to as either bent (sp2) or linear (sp). Even the oxo can be sp2 or sp hybridized. The triply bonded oxo, similar to carbon monoxide, is partially positive at the oxygen atom and unreactive toward Brønsted acids at the oxygen atom. When such a complex is reduced, the triple bond can be converted to a double bond at which point the oxygen no longer bears a partial positive charge and is reactive toward acid.
Conventions
Bonding representations
Imido ligands, also known as imides or nitrenes, most commonly form "linear six electron bonds" with metal centers. Bent imidos are a rarity limited by complexes electron count, orbital bonding availability, or some similar phenomenon. It is common to draw only two lines of bonding for all imidos, including the most common linear imidos with a six electron bonding interaction to the metal center. Similarly amido complexes are usually drawn with a single line even though most amido bonds involve four electrons. Alkoxides are generally drawn with a single bond although both two and four electron bonds are common. Oxo can be drawn with two lines regardless of whether four electrons or six are involved in the bond, although it is not uncommon to see six electron oxo bonds represented with three lines.
Representing oxidation states
There are two motifs to indicate a metal oxidation state based around the actual charge separation of the metal center. Oxidation states up to +3 are believed to be an accurate representation of the charge separation experienced by the metal center. For oxidation states of +4 and larger, the oxidation state becomes more of a formalism with much of the positive charge distributed between the ligands. This distinction can be expressed by using a Roman numeral for the lower oxidation states in the upper right of the metal atomic symbol and an Arabic number with a plus sign for the higher oxidation states (see the example below). This formalism is not rigorously followed and the use of Roman numerals to represent higher oxidation states is common.
[MIIILn]3+ vs. [O=M5+Ln]3+
References
Further reading (specialized literature)
Heidt, L.J.; Koster, G.F.; Johnson, A.M. "Experimental and Crystal Field Study of the Absorption Spectrum at 2000 to 8000 A of to Manganous Perchlorate in Aqueous Perchloric Acid" J. Am. Chem. Soc. 1959, 80, 6471–6477.
Rohde,J; In,J.; Lim, M.H.; Brennessel, W.W.; Bukowski, M.R.; Stubna, A.; Muonck, E.; Nam, W.; Que L. "Crystallographic and Spectroscopic Characterization of a Nonheme Fe(IV)O Complex" Science VOL 299 1037–1039.
Decker, A.; Rohde,J.; Que, L.; Solomon, E.I. "Spectroscopic and Quantum Chemical Characterization of the Electronic Structure and Bonding in a Non-Heme FeIVO Complex" J. Am. Chem. Soc. 2004, 126, 5378–5379.
Aliaga-Alcalde, N.; George, S.D.; Mienert, B.; Bill, E.; Wieghardt, K.; Neese, F. "The Geometric and Electronic Structure of [(cyclam-acetato)Fe(N)]+: A Genuine Iron(V) Species with a Ground-State Spin S=1/2" Angew. Chem. Int. Ed. 2005, 44, 2908–2912.
Chemical bonding
Coordination chemistry | Metal–ligand multiple bond | [
"Physics",
"Chemistry",
"Materials_science"
] | 1,435 | [
"Chemical bonding",
"Coordination chemistry",
"Condensed matter physics",
"nan"
] |
16,286,633 | https://en.wikipedia.org/wiki/Lavoir | A lavoir (, wash-house) is a public place set aside for the washing of clothes. Communal washing places were common in Europe until industrial washing was introduced, and this process in turn was replaced by domestic washing machines and by self-service laundries (British English: laundrette; American English: laundromat) The English word is borrowed from the French language, which also uses the expression , "public basin".
Description
Lavoirs were built from the seventeenth to the early twentieth centuries. With Baron Haussmann's redesign of Paris in the 1850s, a free lavoir was established in every neighbourhood, and government grants encouraged municipalities across France to construct their own. Lavoirs are more common in certain areas, such as around the Canal du Midi.
Lavoirs are commonly sited on a spring or set over or beside a river. Many lavoirs are provided with roofs for shelter. With the coming of piped water supplies and modern drainage, lavoirs have been steadily falling into disuse although a number of communities have restored ancient lavoirs, some of which date back to the 10th century.
There are also ("laundry boats") in some towns on the banks of large rivers such as Paris and Lyon.
Gallery
See also
Baths and wash houses in Britain
Bleachfield
Dhobi ghat, an outdoor laundry place in South Asia
Dhobi Ghat
Laundry#Washhouses
References
External links
Les lavoirs de France
Lavoirs in the department Aube
Lavoirs in Champagne-Ardenne
Lavoirs in Burgundy and Franche-comté
Laundry places
Buildings and structures by type
Water
Women's history | Lavoir | [
"Engineering",
"Environmental_science"
] | 342 | [
"Water",
"Hydrology",
"Buildings and structures by type",
"Architecture"
] |
16,286,691 | https://en.wikipedia.org/wiki/AU-rich%20element | Adenylate-uridylate-rich elements (AU-rich elements; AREs) are found in the 3' untranslated region (UTR) of many messenger RNAs (mRNAs) that code for proto-oncogenes, nuclear transcription factors, and cytokines. AREs are one of the most common determinants of RNA stability in mammalian cells. The function of AREs was originally discovered by Shaw and Kamen in 1986.
AREs are defined as a region with frequent adenine and uridine bases in a mRNA. They usually target the mRNA for rapid degradation.
ARE-directed mRNA degradation is influenced by many exogenous factors, including phorbol esters, calcium ionophores, cytokines, and transcription inhibitors. These observations suggest that AREs play a critical role in the regulation of gene transcription during cell growth and differentiation, and the immune response. As evidence of its critical role, deletion of the AREs from the 3'UTR in either the TNF gene or GM-CSF gene in mice leads to over expression of each respective gene product, causing dramatic disease phenotypes.
AREs have been divided into three classes with different sequences. The best characterised adenylate uridylate (AU)-rich Elements have a core sequence of AUUUA within U-rich sequences (for example WWWU(AUUUA)UUUW where W is A or U). This lies within a 50–150 base sequence, repeats of the core AUUUA element are often required for function.
A number of different proteins (e.g. HuA, HuB, HuC, HuD, HuR) bind to these elements and stabilise the mRNA while others (AUF1, TTP, BRF1, TIA-1, TIAR, and KSRP) destabilise the mRNA, miRNAs may also bind to some of them. For example, the human microRNA, miR16, contains an UAAAUAUU sequence that is complementary to the ARE sequence and appears to be required for ARE-mRNA turnover. HuD (also called ELAVL4) binds to AREs and increases the half-life of ARE-bearing mRNAs in neurons during brain development and plasticity.
AREsite—a database for ARE containing genes—has recently been developed with the aim to provide detailed bioinformatic characterization of AU-rich elements.
Classifications
Class I ARE elements, like the c-fos gene, have dispersed AUUUA motifs within or near U-rich regions.
Class II elements, like the GM-CSF gene, have overlapping AUUUA motifs within or near U-rich regions.
Class III elements, like the c-jun gene, are a much less well-defined class—they have a U-rich region but no AUUUA repeats.
No real ARE consensus sequence has been determined yet, and these categories are based neither on the same biological functions, nor on the homologous proteins.
Mechanism of ARE-mediated decay
AREs are recognized by RNA binding proteins such as tristetraprolin (TTP), AUF1, and Hu Antigen R (HuR). Although the exact mechanism is not very well understood, recent publications have attempted to propose the action of some of these proteins. AUF1, also known as hnRNP D, binds AREs through RNA recognition motifs (RRMs). AUF1 is also known to interact with the translation initiation factor eIF4G and with poly(A)-binding protein, indicating that AUF1 senses the translational status of mRNA and decays accordingly through the excision of the poly(A) tail.
TTP's (ZFP36's) expression is rapidly induced by insulin. Immunoprecipitation experiments have shown that TTP co-precipitates with an exosome, suggesting that it helps recruit exosomes to the mRNA containing AREs. Alternatively, HuR proteins have a stabilizing effect—their binding to AREs increases the half-life of mRNAs. Similar to other RNA-binding proteins, this class of proteins contain three RRMs, two of which are specific to ARE elements. A likely mechanism for HuR action relies on the idea that these proteins compete with other proteins that normally have a destabilizing effect on mRNAs. HuRs are involved in genotoxic response—they accumulate in the cytoplasm in response to UV exposure and stabilize mRNAs that encode proteins involved in DNA repair.
Disease
Problems with mRNA stability have been identified in viral genomes, cancer cells, and various diseases. Research shows that many of these problems arise because of faulty ARE function. Deficiency of the ZFP36 family show that ZFP36 ARE binding proteins are critical regulators of T cell homeostasis and autoimmunity. Some of these problems have been listed below:
The c-fos gene produces a transcription factor that is activated in several cancers, the ARE present in c-fos plays a role in its post-transcriptional regulation.
c-myc gene, also responsible for producing transcription factors found in several cancers, the ARE present in c-myc plays a role in its post-transcriptional regulation.
The Cox-2 gene catalyses the production of prostaglandins—it overexpresses in several cancers, and is stabilized by the binding of CUGBP2 RNA-binding protein to ARE
References
External links
Review of original publication discovering AU-rich elements
Pillars link to original 1986 Cell publication discovering AU-rich elements
mRNA Translational blockade by AU-rich elements
Brief introduction to mRNA regulatory elements
ARED: AU-rich element database
Transterm page for AU-Rich Element
AREsite: An online resource for the analysis of AREs
RNA
Gene expression
Cis-regulatory RNA elements | AU-rich element | [
"Chemistry",
"Biology"
] | 1,189 | [
"Gene expression",
"Molecular genetics",
"Cellular processes",
"Molecular biology",
"Biochemistry"
] |
16,286,907 | https://en.wikipedia.org/wiki/Prefix%20delegation | IP networks are divided logically into subnetworks. Computers in the same subnetwork have the same address prefix. For example, in a typical home network with legacy Internet Protocol version 4, the network prefix would be something like 192.168.1.0/24, as expressed in CIDR notation.
With IPv4, commonly home networks use private addresses (defined in ) that are non-routable on the public Internet and use address translation to convert to routable addresses when connecting to hosts outside the local network. Business networks typically had manually provisioned subnetwork prefixes. In IPv6 global addresses are used end-to-end, so even home networks may need to distribute public, routable IP addresses to hosts.
Since it would not be practical to manually provision networks at scale, in IPv6 networking, DHCPv6 prefix delegation (; § 6.3) is used to assign a network address prefix and automate configuration and provisioning of the public routable addresses for the network. In the typical case of a home network, for example, the home router uses DHCPv6 to request a network prefix from the ISP's DHCPv6 server. Once assigned, the ISP routes this network to the customer's home router and the home router starts advertising the new address space to hosts on the network, either via SLAAC or using DHCPv6.
DHCPv6 Prefix Delegation is supported by most ISPs who provide native IPv6 for consumers on fixed networks.
Prefix delegation is generally not supported on cellular networks, for example LTE or 5G. Most cellular networks route a fixed /64 prefix to the subscriber. Personal hotspots may still provide IPv6 access to hosts on the network by using a different technique called Proxy Neighbor Discovery or using the technique described in . One of the reasons why cellular networks may not yet support prefix delegation is that the operators want to use prefixes they can aggregate to a single route. To solve this, defines an optional mechanism and the related DHCPv6 option to allow exclusion of one specific prefix from a delegated prefix set.
External links
Computer networks engineering
IPv6 | Prefix delegation | [
"Technology",
"Engineering"
] | 451 | [
"Computing stubs",
"Computer networks engineering",
"Computer engineering",
"Computer network stubs"
] |
16,287,087 | https://en.wikipedia.org/wiki/Biological%20pharmacist | In France and in other countries like Portugal, Spain, Belgium or Switzerland, a Biological pharmacist (called Pharmacien biologiste in France) is a Pharmacist specialized in Clinical Biology a speciality similar to Clinical Pathology.
They have almost the same rights as Medical Doctors specialized in this discipline. They both are called a "Clinical biologist"".
These Pharm.D. follow a "post-graduate" formation in hospital's medical laboratories.
In France, this specialization called "Internat de Biologie médicale" is a residency and lasts fours years after the five undergraduate years common to all pharmacists.
External links
Reglementation for French Residency in Clinical Pathology (Biologie médicale)
Curriculum Content of French Resident formation in Clinical Pathology, First Level and Second Level
See also
Pathology
Medical laboratory
Anatomic pathology
Medical technologist
Veterinary pathology
Clinical Biologist
Pathology | Biological pharmacist | [
"Biology"
] | 182 | [
"Pathology"
] |
16,287,130 | https://en.wikipedia.org/wiki/Line%20of%20greatest%20slope | In topography, the line of greatest slope is a curve following the steepest slope. In mountain biking and skiing, the line of greatest slope is sometimes called the fall line.
Definition
Mathematically, the line (or path) of greatest slope from a point is determined by the gradient of height, taken as a potential field with respect to an acceleration from the force of gravity. Lines of greatest slope are analogous to lines of force acting to accelerate an object downward at that point. These lines are orthogonal to contour lines. Discounting inertial forces and terrain roughness, a ball rolling down a slope, or water flowing down, will accelerate in the direction of greatest slope.
Applications
Mountain biking
In mountain biking the line of greatest slope defines the fall line, which is the path a trail will follow to descend a hill or mountain with the shortest path, and will also cause the rider to gain the most velocity (assuming brakes are not used, and other factors such as rolling resistance are equal).
Mountain climbing
In mountain climbing, the line of greatest slope defines the fall line, which is the path a climber will take to gain the most elevation with the shortest possible path.
Map reading
The line of greatest slope has practical significance in map reading. On the terrain it is often far more discernible, even intuitively obvious, rather than accurately picking out the consistent height level on what is likely the undulating uneven ground along the ground represented on the contour line. But knowing that a greatest slope vector is orthogonal to the contour line, one can readily deduce the direction of the contour lines from the line of greatest slope. The extent and overall direction of the contour line to a map scale can only be found on the topographic map.
By noting the corresponding compass vector, walking along the contour one can line up a hand held compass aligning the expected direction, and eye-balling the line of contour's estimated level, move up or down along the bearing faster— to closely locate a desired point (planned point) along the hillside. Pragmatically, this can be 'good enough' for rough project landscaping, such as timber clear cutting the work site of a structure like a bridge abutment or connecting ramps. The approximation can then be refined by transit and other surveyor tools to construct on target.
See also
Slope
Fall line (topography)
Surface (topology)
References
Cartography
Topography
Surfaces
Geometric topology
Differential geometry of surfaces
Analytic geometry | Line of greatest slope | [
"Mathematics"
] | 498 | [
"Topology",
"Geometric topology"
] |
16,288,564 | https://en.wikipedia.org/wiki/Icilin | Icilin (AG-3-5) is a synthetic super-agonist of the transient receptor potential M8 (TRPM8) ion channel. Although structurally not related to menthol, it produces an extreme sensation of cold, both in humans and animals. It is almost 200 times more potent than menthol, and 2.5 times more efficacious. Despite their similar effects, icilin activates the TRPM8 receptor in a different way than menthol does. Icilin has been shown to be effective in the treatment of pruritus in an experimental model of itch. It is now used as a research tool for the study of TRP channels, although despite its high potency it is less selective for TRPM8 over other related ion channels than are other compounds such as WS-12.
References
External links
2-Hydroxyphenyl compounds
3-Nitrophenyl compounds
Ureas
Pyrimidones
Cooling flavors | Icilin | [
"Chemistry"
] | 204 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs",
"Ureas"
] |
16,288,589 | https://en.wikipedia.org/wiki/John%20Kenneth%20Stille | John Kenneth Stille (May 8, 1930 – July 19, 1989) was an American chemist who discovered the Stille reaction. He received B.A. and M.A. degrees from the University of Arizona before serving in the Navy during the Korean War. He received his Ph.D. from the University of Illinois, where he studied under Carl Shipp Marvel. Stille began his independent career at the University of Iowa in 1957 before moving to Colorado State University in 1977.
While at the University of Arizona, Stille met his wife-to-be, Dolores Engelking. He and Dolores were married in 1958 and had two sons, John Robert and James Kenneth.
Stille was killed at age 59 in the United Airlines Flight 232 crash at Sioux City, Iowa.
In 2010, the Nobel Prize in Chemistry was awarded to Richard F. Heck, Ei-ichi Negishi and Akira Suzuki for their work on palladium-catalyzed cross-coupling reactions. The Stille reaction is a key part of palladium-catalyzed cross-coupling chemistry, and it is thought that Stille was a likely candidate for the Nobel Prize before his untimely death.
References
External links
1930 births
1989 deaths
American organic chemists
University of Arizona alumni
University of Illinois Urbana-Champaign alumni
Colorado State University faculty
20th-century American chemists
Victims of aviation accidents or incidents in 1989
Victims of aviation accidents or incidents in the United States
Accidental deaths in Iowa
United States Navy personnel of the Korean War | John Kenneth Stille | [
"Chemistry"
] | 307 | [
"Organic chemists",
"American organic chemists"
] |
16,288,801 | https://en.wikipedia.org/wiki/Resident%20set%20size | In computing, resident set size (RSS) is the portion of memory (measured in kilobytes) occupied by a process that is held in main memory (RAM). The rest of the occupied memory exists in the swap space or file system, either because some parts of the occupied memory were paged out, or because some parts of the executable were never loaded.
See also
Proportional set size (PSS)
Unique set size (USS)
Demand paging
Virtual memory
Working set
Working set size
References
External links
Simple resident set size limits, LWN.net, August 10, 2004, by Jonathan Corbet
ELC: How much memory are applications really using?, LWN.net, April 18, 2007, by Jonathan Corbet
Memory management | Resident set size | [
"Technology"
] | 158 | [
"Operating system stubs",
"Computing stubs"
] |
16,288,924 | https://en.wikipedia.org/wiki/Hjelmslev%27s%20theorem | In geometry, Hjelmslev's theorem, named after Johannes Hjelmslev, is the statement that if points P, Q, R... on a line are isometrically mapped to points P´, Q´, R´... of another line in the same plane, then the midpoints of the segments PP´, QQ´, RR´... also lie on a line.
The proof is easy if one assumes the classification of plane isometries. If the given isometry is odd, in which case it is necessarily either a reflection in a line or a glide-reflection (the product of three reflections in a line and two perpendiculars to it), then the statement is true of any points in the plane whatsoever: the midpoint of PP´ lies upon the axis of the (glide-)reflection for any P. If the isometry is even, compose it with reflection in line PQR to obtain an odd isometry with the same effect on P, Q, R... and apply the previous remark.
The importance of the theorem lies in the fact that it has a different proof that does not presuppose the parallel postulate and is therefore valid in non-Euclidean geometry as well. By its help, the mapping that maps every point P of the plane to the midpoint of the segment P´P´´, where P´and P´´ are the images of P under a rotation (in either sense) by a given acute angle about a given center, is seen to be a collineation mapping the whole hyperbolic plane in a 1-1 way onto the inside of a disk, thus providing a good intuitive notion of the linear structure of the hyperbolic plane. In fact, this is called the Hjelmslev transformation.
References
.
External links
Hjelmslev's Theorem by Jay Warendorff, the Wolfram Demonstrations Project.
Hjelmslev's Theorem from cut-the-knot
Theorems in plane geometry | Hjelmslev's theorem | [
"Mathematics"
] | 419 | [
"Theorems in plane geometry",
"Theorems in geometry"
] |
16,289,428 | https://en.wikipedia.org/wiki/Lonesome%20George | Lonesome George ( or , 1910 – June 24, 2012) was a male Pinta Island tortoise (Chelonoidis niger abingdonii) and the last known individual of the subspecies. In his last years, he was known as the rarest creature in the world. George serves as an important symbol for conservation efforts in the Galápagos Islands and throughout the world.
Discovery
George was first seen on the island of Pinta on November 1, 1971, by Hungarian malacologist József Vágvölgyi. The island's vegetation had been devastated by introduced feral goats, and the indigenous C. n. abingdonii population had been reduced to a single individual. It is thought that he was named after a character played by American actor George Gobel. He was relocated for his own safety to the Charles Darwin Research Station on Santa Cruz Island, where he spent his life under the care of Fausto Llerena, for whom the tortoise breeding center is named.
It was hoped that more Pinta Island tortoises would be found, either on Pinta Island or in one of the world's zoos, similar to the discovery of the Española Island male in San Diego. No other Pinta Island tortoises were found. The Pinta Island tortoise was pronounced functionally extinct, as George was in captivity.
Mating attempts
Over the decades, all attempts at mating Lonesome George had been unsuccessful. This prompted researchers at the Darwin Station to offer a $10,000 reward for a suitable mate.
Until January 2011, George was penned with two females of the species Chelonoidis niger becki (from the Wolf Volcano region of Isabela Island), in the hope his genotype would be retained in any resulting progeny. This species was then thought to be genetically closest to George's; however, any potential offspring would have been hybrids, not purebreds of the Pinta Island species.
In July 2008, George mated with one of his female companions. 13 eggs were collected and placed in incubators. On November 11, 2008, the Charles Darwin Foundation reported 80% of the eggs showed weight loss characteristic of being inviable. By December 2008, the remaining eggs had failed to hatch and X-rays showed that they were inviable.
On July 23, 2009, exactly one year after announcing George had mated, the Galápagos National Park announced one of George's female companions had laid a second clutch of five eggs. The park authority expressed its hope for the second clutch of eggs, which it said were in perfect condition. The eggs were moved to an incubator, but on December 16, it was announced that the incubation period had ended and the eggs were inviable (as was a third batch of six eggs laid by the other female).
In November 1999, scientists reported Lonesome George was "very closely related to tortoises" from Española Island (C. n. hoodensis) and San Cristóbal Island (C. n. chathamensis). On January 20, 2011, two individual C. n. hoodensis female partners were imported to the Charles Darwin Research Station, where George lived.
Death
On June 24, 2012, at 8:00 A.M. local time, Galápagos National Park director Edwin Naula announced that Lonesome George had been found dead by Fausto Llerena, who had looked after him for forty years. Naula suspected that the cause of death was cardiac arrest. A necropsy confirmed that George died from natural causes. The body of Lonesome George was frozen and shipped to the American Museum of Natural History in New York City to be preserved by taxidermists. The preservation work was carried out by the museum's taxidermist George Dante, with input from scientists.
After a short display at the museum, it was expected that Lonesome George's taxidermy would be returned to the Galápagos and displayed at the Galapagos National Park headquarters on Santa Cruz Island for future generations to see. However, a dispute broke out between an Ecuadorean ministry and the Galápagos Islands. The Ecuadorean government wanted the taxidermy to be shown in the capital, Quito, but the Galápagos local mayor said Lonesome George was a symbol of the islands and should return home.
On February 17, 2017, Lonesome George's taxidermy was flown back to the Galápagos Islands, where it is currently on display in the Fausto Llerena Breeding Center.
Biological conservation
In November 2012, in the journal Biological Conservation, researchers reported identifying 17 tortoises that are partially descended from the same species as Lonesome George, leading them to speculate that closely related purebred individuals of that species may still be alive.
In December 2015, it was reported that the discovery of another subspecies, Chelonoidis niger donfaustoi, by Yale researchers had a 90% D.N.A. match to that of the Pinta Island tortoise and that scientists believe this could possibly be used to resurrect the species. This could mean that he is not the last of his kind.
In December 2018, a paper was published by Quesada et al. describing the sequencing of George's genome and some of his aging-related genes. They estimated that the population of C. n. abingdonii had been declining for the past one million years and identified lineage-specific variants affecting DNA repair genes, proteostasis, metabolism regulation and immune response as key processes during the evolution of giant tortoises via effects on longevity and resistance to infection.
In February 2020, the Galápagos National Park, along with the Galápagos Conservancy, reported that a female tortoise was directly related to the species that Lonesome George was a part of. This female was among thirty tortoises that were found to be related to two species that are considered extinct.
See also
Jonathan (tortoise)
The Life Cairn
Mr Turpen
Timothy (tortoise)
Toughie (frog)
References
Individual tortoises
2012 animal deaths
Endlings
Individual taxidermy exhibits
1910 animal births | Lonesome George | [
"Biology"
] | 1,269 | [
"Individual organisms",
"Endlings"
] |
7,368,905 | https://en.wikipedia.org/wiki/Banksman | In Irish and British civil engineering, a banksman is the person who directs the operation of a crane or larger vehicle from the point near where loads are attached and detached. The term 'dogman' may be used in Australia and New Zealand, while 'spotter' is the more common term in United States.
Offshore & oil and gas
The general term for a professional banksman offshore is a 'rigger' or deck crew. A team of riggers will manage lifting operations. There are specific methods, pieces of equipment, and safety protocol for many different types of loads. Offshore, on rigs or vessels, most equipment and materials will arrive on location, transferred by boat utilising a crane, therefore banksmen play an important role in the marine and offshore industries.
Contemporary
Crane or large vehicle drivers do not always have clear visibility of the loading area, especially when tower cranes are employed. The banksman is in charge of the crane movements from the point of loading and unloading. They may use a system of hand signals or a radio link.
A banksman may also be responsible for directing the movement and loading/unloading of lorries, or directing the movement of other plant. A banksman may also control the movements of an excavator, by carefully monitoring the bucket for any obstructions or underground services.
In many countries, banksmen are required to meet a regulated standard, such as laid down by the UK's Health and Safety Executive; in the UK over a quarter of vehicle deaths at work are due to reversing vehicles.
Usage timeline
1825: the man stationed at the bank or top of a pit who unhooked and emptied the laden corves into carts or wagons, from a frame or stage.
1849: the man who drew the full tubs from the cages at the surface, when wound up by the engine, and replaced them with empty ones; he also put the full tubs to the weighing machine, and thence to the skreens, upon which he teemed the coals. It was also his duty to keep an account of the quantity of coals and stones drawn each day.
1894: a person who controlled the unloading and loading of the cage at the pit top, and signalled the descent of the workmen.
References
External links
RoSPA's Safety course material
Health and Safety executive Banksman's Signals
Durham Mining Museum Historic use in coal industry.
Cornish Tin Mining Terms.
The Health and Safety (Safety Signs and Signals) The UK Health and Safety (Safety Signs and Signals) Regulations 1996, PART IX Minimum requirements for hand signals.
Construction
Construction trades workers | Banksman | [
"Engineering"
] | 534 | [
"Construction"
] |
7,371,134 | https://en.wikipedia.org/wiki/Anthroposphere | The anthroposphere refers to that part of the Earth system that is made or modified by humans for use in human activities and human habitats. The term has been suggested for inclusion as one of the Earth's spheres, while others use the related term technosphere. The term "anthroposphere" was first coined by Austrian geologist Eduard Suess in 1862.
The anthroposphere can be viewed as a human-generated equivalent to the biosphere. While the biosphere is the total biomass of the Earth and its interaction with its systems, the anthroposphere is the total mass of human-generated systems and materials, including the human population, and its interaction with the Earth's systems. A recent study estimated the mass of anthropogenic creations as 1.1 trillion tons in 2020, equivalent to the mass of all living organisms that comprise the biosphere. However, while the biosphere is able to efficiently produce and recycle materials through processes like photosynthesis and decomposition, the anthroposphere is highly inefficient at sustaining itself. As human technology becomes more evolved, such as that required to launch objects into orbit or to cause deforestation, the impact of human activities on the environment potentially increases. The anthroposphere is the youngest of all the Earth's spheres, yet has made an enormous impact on the Earth and its systems in a very short time.
Some consider the term anthroposphere to be synonymous with the noosphere, though the noosphere is often used to refer specifically to the sphere of rational human thought, or ‘the terrestrial sphere of thinking substance’. The anthroposphere is also closely related to the concept of the "technosphere" developed by geologist Peter Haff, historian of science Jürgen Renn, and others. The technosphere refers to all of the technological objects and systems manufactured and created by humans, as contrasted for instance to the biosphere. The technosphere is also distinct from the anthroposphere in these sense that the anthroposphere encompasses not only technologies but cultural, social, economic, and political systems, as well as human behaviors and practices.
Aspects of the anthroposphere include: mines from which minerals are obtained; mechanized agriculture and transportation which support the global food system; oil and gas fields; computer-based systems including the Internet; educational systems; landfills; factories; atmospheric pollution; artificial satellites in space, both active satellites and space junk; forestry and deforestation; urban development; transportation systems including roads, highways, and subways; nuclear installations; warfare.
Technofossils are another interesting aspect of the anthroposphere. These can include objects like mobile phones that contain a diverse range of metals and man-made materials, raw materials like aluminum that do not exist in nature, and agglomerations of plastics created in areas like the Pacific Garbage Patch and on the beaches of the Pacific Islands.
See also
Anthropocene
Anthropogenic metabolism
biomass
space junk
References
External links
The Anthroposphere
Wikiversity:Technology as a threat or promise for life and its forms
Earth sciences
Artificial objects | Anthroposphere | [
"Physics"
] | 637 | [
"Artificial objects",
"Physical objects",
"Matter"
] |
7,371,182 | https://en.wikipedia.org/wiki/QPNC-PAGE | QPNC-PAGE, or Quantitative Preparative Native Continuous Polyacrylamide Gel Electrophoresis, is a bioanalytical, one-dimensional, high-resolution and high-precision electrophoresis technique applied in biochemistry and bioinorganic chemistry to separate proteins by isoelectric point and by continuous elution from a gel column for further characterization.
This hybrid variant of native analytical gel electrophoresis and preparative polyacrylamide gel electrophoresis is used to quantitatively resolve physiological concentrations of macromolecules with high recovery, for example, into active or native metalloproteins in biological samples or into properly and improperly folded metal cofactor-containing proteins in complex protein mixtures.
Introduction
Proteins perform several functions in living organisms, including catalytic reactions and transport of molecules or ions within the cells, the organs or the whole body. The understanding of the processes in human organisms, which are mainly driven by biochemical reactions and protein-protein interactions, depends to a great extent on the ability to isolate active proteins in biological samples for more detailed examination of chemical structure and physiological function. This essential information can imply an important indication of a patient's state of health.
As about 30–40% of all known proteins contain one or more metal ion cofactors (e.g., ceruloplasmin, ferritin, amyloid-beta precursor protein, matrix metalloproteinase, or metallochaperones), especially native and denatured metalloproteins have to be isolated, identified and quantified after liquid biopsy. Many of these cofactors (e.g., iron, copper, or zinc) play a key role in vital enzymatic catalytic processes or stabilize globular protein molecules driven by protein-cofactor interactions. Therefore, the high-precision gel electrophoresis and comparable separation techniques are highly relevant as initial step of protein and trace metal speciation analysis, subsequently, followed by modern mass spectrometric and magnetic resonance methods for quantifying and identifying the soluble proteins of interest.
Method
Separation and buffering mechanisms
In gel electrophoresis proteins are normally separated by charge, size, or shape. The aim of isoelectric focusing (IEF), for example, is to separate proteins according to their isoelectric point (pI), thus, according to their charge at different pH values. Here, a similar mechanism is accomplished in a commercially available electrophoresis chamber for separating charged biomolecules, for example, superoxide dismutase (SOD) or allergens, at constant pH conditions and different velocities of migration depending on different isoelectric points of zwitterions. The separated (metal) proteins elute sequentially, starting with the lowest (pI > 2–4) and ending with the highest pI (pI < 10.0) of the dissolved protein molecules to be analyzed.
Due to the specific properties of the prepared gel and electrophoresis buffer solution which is basic and contains Tris-HCl and NaN3, most proteins of a biological system (e.g., Helicobacter pylori) are charged negatively in the solution, and will migrate from the cathode to the anode due to the electric field. In general, reaction equation (1) shows that the carboxyl side group of a proteinogenic amino acid is negatively charged, equation (2) that the amino side groups are electrically neutral under these conditions:
(1) R-COOH + OH− → R-COO− + H2O
(2) R-NH3+ + OH− → R-NH2 + H2O
At the anode, electrochemically-generated hydrogen ions react with Tris molecules to form monovalent Tris ions (3). The positively charged Tris ions migrate through the gel to the cathode where they neutralise hydroxide ions to form Tris molecules and water (4):
(3) (HOCH2)3CNH2 + H+ → [(HOCH2)3CNH3]+
(4) [(HOCH2)3CNH3]+ + OH− → (HOCH2)3CNH2 + H2O
Thus, the Tris-based buffering mechanism causes a constant pH in the continuous buffer system with a high buffer capacity.
At 25 °C Tris buffer has an effective pH range between 7.5 and 9.0. Under the conditions given here (addressing the concentration of buffer components, buffering mechanism, pH and temperature) the effective pH is shifted in the range of about 10.0 to 10.5. Native buffer systems all have low conductivity and range in pH from 3.8 to 10.2. Continuous native buffer systems are thus used to separate proteins according their pI.
Although the pH value (10.00) of the electrophoresis buffer does not correspond to a physiological pH value within a cell or tissue type, the separated ring-shaped protein bands are eluted continuously into a physiological buffer solution (pH 8.00) and isolated in different fractions. Provided that irreversible denaturation cannot be demonstrated by an independent procedure, most protein molecules are stable in aqueous solution, at pH values from 3 to 10 if the temperature is below 50 °C. As the Joule heat and temperature generated during electrophoresis may exceed 50 °C, and thus, have a negative impact on the stability and migration behavior of proteins in the gel, the separation system, consisting of the electrophoresis chamber, fraction collector and other devices, is cooled in a refrigerator at 4 °C, thus, greatly reducing the risk of heat convection currents. Overheating of the gel is impeded by internal cooling circuit of the gel column as an integrated part of the electrophoresis chamber and by generating a constant power by the power supply.
Gel properties and polymerization time
Best polymerization conditions for acrylamide gels are obtained at 25–30 °C and polymerization seems terminated after 20–30 min of reaction although residual monomers (10–30%) are detected after this time. The co-polymerization of acrylamide (AA) monomer/N,N'-Methylenebisacrylamide (Bis-AA) cross-linker initiated by ammonium persulfate (APS)/tetramethylethylenediamine (TEMED) reactions, is most efficient at alkaline pH of the acrylamide solution. Thereby, acrylamide chains are created and cross-linked at a time. Due to the properties of the electrophoresis buffer, the gel polymerization is conducted at pH 10.00 making sure an efficient use of TEMED and APS as catalysts of the polymerization reaction, and concurrently, suppressing a competitive hydrolysis of the produced acrylamide polymer network. Polymer networks are three-dimensionally linked polymer chains. Otherwise, proteins could be modified by reaction with unpolymerized monomers of acrylamide, forming covalent acrylamide adduction products that may result in multiple bands.
Additionally, the time of polymerization of a gel can directly affect the peak-elution times of separated metalloproteins in the electropherogram due to the compression and dilatation of the gels and their pores if the incubation times for the reaction mixture (gel solution) used to prepare a gel are not optimized. In order to ensure maximum reproducibility in gel pore size and to obtain a fully polymerized and non-restrictive large pore gel for a PAGE run, the polyacrylamide gel is polymerized for a time period of 69 hr at room temperature (RT) in a gel column located on the casting stand. The exothermic heat generated by the polymerization processes is dissipated constantly while the temperature may rise rapidly to over 75 °C in the first minutes, after which it falls slowly. After 69 hr, the gel has reached room temperature and is in its lowest energy state, as the basic chemical reactions and gelation are complete. Gelation means that the
solvent (water) gets immobilized within the polymer network by means of hydrogen bonds and also van der Waals forces. As a result, the prepared gel is homogeneous (in terms of homogeneous distribution of cross-links throughout the gel sample), inherently stable and free of monomers or radicals. Fresh polyacrylamide gels are further hydrophilic, electrically neutral and do not bind proteins. Sieving effects due to gravity-induced compression of the gel can be excluded for the same reasons. Thus, in a medium without molecular sieving properties a high-resolution can be expected.
Before an electrophoretic run is started the prepared 4% T (total polymer content (T)), 2.67% C (cross-linker concentration (C)) gel is pre-run to equilibrate it. It is essentially non-sieving and optimal for electrophoresis of proteins greater than or equal to 200 ku. Proteins migrate in it more or less on the basis of their free mobility. For these reasons interactions of the gel with the biomolecules are negligibly low, and thus, the proteins separate cleanly and predictably at a polymerization time of 69 hr. The separated metalloproteins including biomolecules ranging from approximately < 1 ku to greater than 30 ku (e.g., metal chaperones, prions, metal transport proteins, amyloids, metalloenzymes, metallopeptides, metallothionein, phytochelatins) are not dissociated into apoproteins and metal cofactors.
Reproducibility and recovery
The bioactive structures (native or 3D conformation or shape) of the isolated protein molecules do not undergo any significant conformational changes. Thus, active metal cofactor-containing proteins can be isolated reproducibly in the same fractions after a PAGE run. A shifting peak in the respective electropherogram indicates that the standardized time of gel polymerization (69 hr, RT) is not implemented in a PAGE experiment. A lower deviation of the standardized polymerization time (< 69 hr) stands for incomplete polymerization, and thus, for inherent instability due to gel softening during the cross-linking of polymers as the material reaches swelling equilibrium, whereas exceeding this time limit (> 69 hr) is an indicator of gel aging. The phenomenon of gel aging is closely connected to long-term viscosity decrease of aqueous polyacrylamide solutions and increased swelling of hydrogels.
Under standard conditions, metalloproteins with different molecular mass ranges and isoelectric points have been recovered in biologically active form at a quantitative yield of more than 95%. By preparative SDS-PAGE standard proteins (cytochrome c, aldolase, ovalbumin and bovine serum albumin) with molecular masses of 14–66 ku can be recovered with an average yield of about 73.6%. Preparative isotachophoresis (ITP) is applied for isolating palladium-containing proteins with molecular masses of 362 ku (recovery: 67%) and 158 ku (recovery: 97%).
Quantification and identification
Physiological concentrations (ppb-range) of Fe, Cu, Zn, Ni, Mo, Pd, Co, Mn, Pt, Cr, Cd and other metal cofactors can be identified and absolutely quantified in an aliquot of a fraction by inductively coupled plasma mass spectrometry (ICP-MS) or total reflection X-ray fluorescence (TXRF), for example. In case of ICP-MS the structural information of the associated metallobiomolecules is irreversibly lost due to ionization of the sample with plasma. Another established high sensitive detection method for the determination of trace elements in biological samples is graphite furnace atomic absorption spectrometry (GF-AAS). Because of high purity and optimized concentration of the separated metalloproteins, for example, therapeutic recombinant plant-made pharmaceuticals such as copper chaperone for superoxide dismutase (CCS) from medicinal plants, in a few specific PAGE fractions, the related structures of these bioactive analytes can be elucidated quantitatively by using solution NMR spectroscopy under non-denaturing conditions.
Applications
Improperly folded metal proteins, for example, CCS or Cu-Zn-superoxide dismutase (SOD1) present in brain, blood or other clinical samples, are indicative of neurodegenerative diseases like Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS). Active CCS or SOD molecules contribute to intracellular homeostatic control of essential metal ion species (e.g., Cu1+/2+, Zn2+, Fe2+/3+, Mn2+, Ni3+) in organisms, and thus, these biomolecules can balance pro-oxidative and antioxidative processes in the cytoplasm. Otherwise, free or loosely bound transition metal ions take part in Fenton-like reactions in which deleterious hydroxyl radical is formed, which unrestrained would be destructive to proteins. The loss of active CCS increases the amyloid-β production in neurons which, in turn, is a major pathological hallmark of AD. Therefore, copper chaperone for superoxide dismutase is proposed to be one of the most promising biomarkers of Cu toxicity in these diseases. CCS should be analysed primarily in blood because a meta-analysis of serum data showed that AD patients have higher levels of serum Cu than healthy controls.
Persons
QPNC-PAGE, originally ‘PNC-PAGE’, was developed in the late 1990s to optimize the chemical composition and physical properties of the acrylamide gel matrix. It was invented by Bernd Kastenholz and significantly influenced by the pioneering work of David E. Garfin and Andreas Chrambach. Several other cited authors have also contributed with their research work.
See also
Agarose gel electrophoresis
Electroelution
Electrokinetics
Electrophoresis
Gel electrophoresis
Gel electrophoresis of proteins
Inductively coupled plasma mass spectrometry
Metallome
Nuclear magnetic resonance spectroscopy of proteins
Protein mass spectrometry
Protein purification
Quantitative proteomics
Size-exclusion chromatography
References
Further reading
External links
Advancing Electrokinetic Science by the AES Electrophoresis Society
Protein Purification Protocols by The Hebrew University of Jerusalem
Analytical chemistry
Electrophoresis
Laboratory techniques
Biomedicine | QPNC-PAGE | [
"Chemistry",
"Biology"
] | 3,094 | [
"Biomedicine",
"Instrumental analysis",
"Biochemical separation processes",
"Molecular biology techniques",
"nan",
"Electrophoresis"
] |
7,371,620 | https://en.wikipedia.org/wiki/Peg%20%28unit%29 | A peg is a unit of volume, typically used to measure amounts of liquor in the Indian subcontinent. Informally, a peg is an undefined measure of any alcoholic drink poured in a glass.
The terms "large (bara) peg" and "small (chota) peg" are equal to 60ml and 30ml, respectively, with "peg" alone simply referring to a 60ml peg. The "chota peg" was often used by the 1940s mythical British Indian Army figure "Colonel Chinstrap" in the UK Radio Serial "ITMA" ("It's That Man Again") who was frequently having Chota Pegs of whisky (and sounded like it in his deliberately slurred speech).
See also
Patiala peg
References
Bartending equipment
Cooking weights and measures
Units of measurement
Units of volume | Peg (unit) | [
"Mathematics"
] | 169 | [
"Units of volume",
"Quantity",
"Units of measurement"
] |
7,371,666 | https://en.wikipedia.org/wiki/Structured%20entity%20relationship%20model | The SERM (structured entity relationship model) is an amplification of the ERM which is commonly used for data modeling. It was first proposed from Prof. Dr. Elmar J. Sinz in 1988. The SERM is commonly used in the SAP-world for the data modeling.
Aims
structuring of large schemes
visualization of existence dependency
avoidance of inconsistencies
avoidance of unnecessary relationshiptypes
SERM symbols
SERM example
Customer and article are independent entities
Every order is referred to one customer. Orders without customers are illegal (order is an ER type). Customers without any orders are legal because they are independent Entities.
To every order there is belonging at least one order item.
Every order item is related to exactly one order.
Every invoice is referred to one customer, as well. Invoices without customers are illegal. Customers without any invoice are legal.
To every invoice there is belonging at least one invoice line item.
Every invoice line item is related to exactly order item. An order item could be calculated or not.
SERM is already in the third normal form
References
Data modeling
Diagrams
Modeling languages | Structured entity relationship model | [
"Engineering"
] | 237 | [
"Data modeling",
"Data engineering"
] |
7,372,153 | https://en.wikipedia.org/wiki/Ho%CA%BBoponopono | () is a traditional Hawaiian practice of reconciliation and forgiveness. The Hawaiian word translates into English simply as correction, with the synonyms manage or supervise. Similar forgiveness practices are performed on islands throughout the South Pacific, including Hawaii, Samoa, Tahiti and New Zealand. Traditional is practiced by Indigenous Hawaiian healers, often within the extended family by a family member.
Polynesian antecedents
In many Polynesian cultures, it is believed that a person's errors (called hara or hala) caused illness. Some believe error angers the gods, others that it attracts malevolent gods, and still others believe the guilt caused by error made one sick. "In most cases, however, specific 'untie-error' rites could be performed to atone for such errors and thereby diminish one's accumulation of them."
Among the islands of Vanuatu in the South Pacific, people believe that illness usually is caused by sexual misconduct or anger. "If you are angry for two or three days, sickness will come," said one local man. The therapy that counters this sickness is confession. The patient, or a family member, may confess. If no one confesses an error, the patient may die. The Vanuatu people believe that secrecy is what gives power to the illness. When the error is confessed, it no longer has power over the person.
Like many other islanders, including Hawaiians, people of Tikopia in the Solomon Islands, and on Rarotonga in the Cook Islands, believe that the sins of the father will fall upon the children. If a child is sick, the parents are suspected of quarreling or misconduct. In addition to sickness, social disorder could cause sterility of land or other disasters. Harmony could be restored only by confession and apology.
In Pukapuka, it was customary to hold sort of a confessional over patients to determine an appropriate course of action in order to heal them.
Similar traditions are found in Samoa, Tahiti, and among the Maori of New Zealand.
Etymology
is defined in the Hawaiian Dictionary as:
(a) "To put to rights; to put in order or shape, correct, revise, adjust, amend, regulate, arrange, rectify, tidy up make orderly or neat, administer, superintend, supervise, manage, edit, work carefully or neatly; to make ready, as canoemen preparing to catch a wave."
(b) "Mental cleansing: family conferences in which relationships were set right (hooponopono) through prayer, discussion, confession, repentance, and mutual restitution and forgiveness."
Literally, is a particle used to make an actualizing verb from the following noun. Here, it creates a verb from the noun , which is defined as: "...goodness, uprightness, morality, moral qualities, correct or proper procedure, excellence, well-being, prosperity, welfare, benefit, true condition or nature, duty; moral, fitting, proper, righteous, right, upright, just, virtuous, fair, beneficial, successful, in perfect order, accurate, correct, eased, relieved; should, ought, must, necessary."
is defined as "to put to rights; to put in order or shape, correct, revise, adjust, amend, regulate, arrange, rectify, tidy up, make orderly or neat."
So can be translated literally as "to make right" or "to make good".
Traditional practice
Hawaiian scholar Nana Veary in her book Change We Must: My Spiritual Journey wrote that hooponopono was a practice in Ancient Hawaii and this is supported by oral histories from contemporary Hawaiian elders. Pukui (born 1895) first recorded her experiences and observations from her childhood in her 1958 book.
Although the word was not used, early Hawaiian historians documented a belief that illness was caused by breaking kapu, or spiritual laws, and that the illness could not be cured until the sufferer atoned for this transgression, often with the assistance of a praying priest () or healing priest (). Forgiveness was sought from the gods or from the person with whom there was a dispute.
Pukui described it as a practice of extended family members meeting to "make right" broken family relations. Some families met daily or weekly, to prevent problems from erupting. Others met when a person became ill, believing that illness was caused by the stress of anger, guilt, recriminations and lack of forgiveness. Kupuna Nana Veary wrote that when any of the children in her family fell ill, her grandmother would ask the parents, "What have you done?" They believed that healing could come only with complete forgiveness of the whole family.
Ritual
The aim of is to correct, restore and maintain good relationships among family members and with their god(s) by getting to the causes and sources of trouble. It is usually conducted by the most senior family member, who gathers the family together. If the family is unable to work through a problem, they turn to a respected outsider.
The process begins with prayer. A statement of the problem is made, and the transgression discussed. Family members are expected to work problems through and cooperate, and not "hold fast to the fault". One or more periods of silence may be taken for reflection on the entanglement of emotions and injuries. Each person's feelings are acknowledged. Then confession, repentance and forgiveness take place. Everyone releases () each other, letting go. They cut off the past (), and together they close the event with a ceremonial feast, called , which often included eating , symbolic of the release.
In a form used by the family of Makaweliweli of the island of Molokai, the completion of is represented by giving the person forgiven a lei made from the fruit of the hala tree.
Modern uses
"Aunty" Malia Craver, who worked with the Queen Liliuokalani Children's Centers (QLCC) for more than 30 years, taught courses in traditional hooponopono. On August 30, 2000, she spoke about it to the United Nations.
Traditional applications
In the late 20th century, courts in Hawaii began to order juvenile and adult offenders to work with an elder who would conduct for their families, as a form of alternative dispute resolution. The is conducted in the traditional way, without court interference, with a practitioner picked by the family from a list of court-approved providers.
Some native practitioners provide to clients who otherwise might seek family counseling.
Freedom from karma
In 1976 Morrnah Simeona, regarded as a healing priest or , adapted the traditional of family mutual forgiveness to the social realities of the modern day. For this she extended it both to a general problem solving process outside the family and to a psycho-spiritual self-help rather than group process.
Simeona's version is influenced by her Christian (Protestant and Catholic) education and her philosophical studies about India, China and Edgar Cayce. Like Hawaiian tradition she emphasizes prayer, confession, repentance, and mutual restitution and forgiveness. Unlike Hawaiian tradition, she describes problems only as the effects of negative karma, saying that "you have to experience by yourself what you have done to others." But that you are the creator of your life circumstances was common knowledge for the people of old as "things we had brought with us from other lifetimes." Any wrongdoing is memorized within oneself and mirrored in every entity and object which was present when the cause happened. As the Law of Cause and Effect predominates in all of life and lifetimes, the purpose of her version is mainly "to release unhappy, negative experiences in past reincarnations, and to resolve and remove traumas from the 'memory banks'." Karmic bondages hinder the evolution of mind, so that "(karmic) cleansing is a requisite for the expansion of awareness". Using her 14-step-process would dissolve those bondages. She did not use mantras or conditioning exercises.
Her teachings include: there is a Divine Creator who takes care of altruistic pleas of Men; "when the phrase 'And it is done' is used after a prayer, it means Man's work ends and God's begins." "Self-Identity" signifies, e.g. during the hooponopono, that the three selves or aspects of consciousness are balanced and connected with the Divine Creator. Different from egoistic prayers, "altruistic prayers like hooponopono, where you also pray for the release of other entities and objects, reach the Divine plane or Cosmos because of their high vibrations. From that plane the Divine energy or "mana" would come," which would transform the painful part of the memory of the wrong actions in all participants to "Pure Light", on whatever plane they are existing; "all are set free". Through this transmutation in the mind the problems will lose their energy for physical effects, and healing or balancing is begun. In this sense, Simeona's mana is not the same as the traditional Polynesian understanding of mana.
Pacifica Seminars, founded by Morrnah Simeona, started the first Ho'oponopono seminars in Germany. Seminars are still held on a regular basis in Germany, Poland, France, and Denmark.
State of Zero
After Simeona's death in 1992, her former student and administrator, Ihaleakala Hew Len, co-authored a book with Joe Vitale called Zero Limits referring to Simeona's Hooponopono teachings. Len makes no claim to be a kahuna. In contrast to Simeona's teachings, the book brings the new idea that the main objective of Hooponopono is getting to the "zero state — it's where we have zero limits. No memories. No identity." To reach this state, which Len called 'Self-I-Dentity thru Ho'oponopono', includes using the mantra, "I love you. I'm sorry. Please forgive me. Thank you." It is based on Len's idea of 100% responsibility, taking responsibility for everyone's actions, not only for one's own. If one would take complete responsibility for one's life, then everything one sees, hears, tastes, touches, or in any way experiences would be one's responsibility because it is in one's life. The problem would not be with one's external reality, it would be with oneself. Total Responsibility, according to Hew Len, advocates that everything exists as a projection from inside the human being.
Footnotes
See also
Restorative Justice
Ifoga
References
Buck, Peter Te Rangi Hiroa, The Coming of the Maori, Wellington, Whitcombe and Tombs (1950)
Chai, Makana Risser, Na Moolelo Lomilomi: The Traditions of Hawaiian Massage & Healing, Bishop Museum Press (2005)
Handy, E.S.Craighill Polynesian Religion, Kraus Reprint & Periodicals (1971)
Kamakau, Samuel, Ka Poe Kahiko (The People of Old), Bishop Museum Press (1992)
Lee, Pali Jae, Ho'opono, I M Publishing (2008)
Lee, Pali Jae, Koko Willis, Tales from the Night Rainbow, Night Rainbow Publishing Co. (1990)
Malo, Davida, (Chun, trans) Ka Moolelo Hawaii: Hawaiian Traditions, First Peoples Productions
Oliver, Douglas, Polynesia in Early Historic Times, Bess Press (2002)
Parsons, Claire F., Healing Practices in the South Pacific, Institute for Polynesian Studies (1995)
Pukui, Mary Kawena and Elbert, Samuel H., University of Hawaii (1986)
Pukui, Mary Kawena, Haertig, E.W. and Lee, Catherine, Nana i ke Kumu: Look to the Source, Vol 1, Hui Hanai (1983)
Pukui, Mary Kawena, E.S. Craighill Handy, The Polynesian Family System in Kau, Hawaii, 1958, Mutual Pub Co, (Hawaii 2006)
Rogers, Kim Steutermann, "Sacred Harmony", Hawaii Magazine (Jan/Feb 2004)
Shook, Victoria E. Hooponopono: Contemporary Uses of a Hawaiian Problem Solving Process, University of Hawaii Press (1986)
Simeona, Morrnah, Self-Identity through Hooponopono, Basic 1, Pacifica Seminars (1990)
Titcomb (1948) "Kava in Hawaii", Journal of the Polynesian Society, 57:105–71, 144
Vitale, Joe, Hew Len Ph.D., Zero Limits, Wiley (2007)
Austronesian spirituality
Conflict (process)
Dispute resolution
Family therapy
Hawaiiana
Hawaiian words and phrases
Culture of Oceania
Spirituality | Hoʻoponopono | [
"Biology"
] | 2,633 | [
"Behavior",
"Aggression",
"Human behavior",
"Conflict (process)"
] |
7,372,292 | https://en.wikipedia.org/wiki/Taro%20Morishima | was a Japanese mathematician specializing in algebra who attended University of Tokyo in Japan. Morishima published at least thirteen papers, including his work on Fermat's Last Theorem. and a collected works volume published in 1990 after his death. He also corresponded several times with American mathematician H. S. Vandiver.
Morishima's Theorem on FLT
Let m be a prime number not exceeding 31. Let p be prime, and let x, y, z be integers such that xp + yp + zp = 0. Assume that p does not divide the product xyz. Then, p² must divide mp − 1-1.
Review
Granville wrote that Morishima's proof could not be accepted.
References
External links
Collected papers at Queen's University
1903 births
1989 deaths
20th-century Japanese mathematicians
Algebraists | Taro Morishima | [
"Mathematics"
] | 168 | [
"Algebra",
"Algebraists"
] |
7,372,595 | https://en.wikipedia.org/wiki/LG%20The%20V%20%28VX9800%29 | The V (LG VX9800) is a CDMA smartphone. It was released under Verizon Wireless in 2005.
Since then, it has been replaced by the enV (VX9900), enV2 (VX9100) and enV3 (VX9200), which are much slimmer and maintain most of the features of The V, while adding a 2.0-megapixel camera and stereo Bluetooth support.
References
External links
Verizon Wireless The V support
LG VX9800 Product information
VX9800
Mobile phones introduced in 2005 | LG The V (VX9800) | [
"Technology"
] | 131 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
7,373,540 | https://en.wikipedia.org/wiki/Remote%20manipulator | A remote manipulator, also known as a telefactor, telemanipulator, or waldo (after the 1942 short story "Waldo" by Robert A. Heinlein which features a man who invents and uses such devices), is a device which, through electronic, hydraulic, or mechanical linkages, allows a hand-like mechanism to be controlled by a human operator. The purpose of such a device is usually to move or manipulate hazardous materials for reasons of safety, similar to the operation and play of a claw crane game.
History
In 1945, the company Central Research Laboratories was given the contract to develop a remote manipulator for the Argonne National Laboratory. The intent was to replace devices which manipulated highly radioactive materials from above a sealed chamber or hot cell, with a mechanism which operated through the side wall of the chamber, allowing a researcher to stand normally while working.
The result was the Master-Slave Manipulator Mk. 8, or MSM-8, which became the iconic remote manipulator seen in newsreels and movies, such as The Andromeda Strain or THX 1138.
Robert A. Heinlein claimed a much earlier origin for remote manipulators. He wrote that he got the idea for "waldos" after reading a 1918 article in Popular Mechanics about "a poor fellow afflicted with myasthenia gravis ... [who] devised complicated lever arrangements to enable him to use what little strength he had." An article in Science Robotics on robots, science fiction, and nuclear accidents discusses how the science fiction waldos are now a major type of real-world robots used in the nuclear industry.
See also
Glovebox
Dextre
Doctor Octopus
Teleoperation
Telerobotics
Master/slave (technology)
Avatar (computing)
Pantograph
Man-Machine
References
External links
Central Research Laboratories web site
A video of a Remote Manipulator being used to make an origami crane
Master-slave manipulator at Argonne National Laboratory
Nuclear technology | Remote manipulator | [
"Physics"
] | 422 | [
"Nuclear technology",
"Nuclear physics"
] |
7,373,582 | https://en.wikipedia.org/wiki/Transgressive%20segregation | In genetics, transgressive segregation is the formation of extreme phenotypes, or transgressive phenotypes, observed in segregated hybrid populations compared to phenotypes observed in the parental lines. The appearance of these transgressive (extreme) phenotypes can be either positive or negative in terms of fitness. If both parents' favorable alleles come together, it will result in a hybrid having a higher fitness than the two parents. The hybrid species will show more genetic variation and variation in gene expression than their parents. As a result, the hybrid species will have some traits that are transgressive (extreme) in nature. Transgressive segregation can allow a hybrid species to populate different environments/niches in which the parent species do not reside, or compete in the existing environment with the parental species.
Causes
Genetic
There are many causes for transgressive segregation in hybrids. One cause can be due to recombination of additive alleles. Recombination results in new pairs of alleles at two or more loci. These different pairs of alleles can give rise to new phenotypes if gene expression has been changed at these loci. Another cause can be elevated mutation rate. When mutation rates are high, it is more probable that a mutation will occur and cause an extreme phenotypic change. Reduced developmental stability is another cause for transgressive segregation. Developmental stability refers to the capability of a genotype to go through a constant development of a phenotype in a certain environmental setting. If there is a disturbance due to genetic or environmental factors, the genotype will be more sensitive to phenotypic changes. Another cause arises from the interaction between two alleles of two different genes, also known as the epistatic effect. Epistasis is the event when one allele at a locus prevents an allele at another locus to express its product as if it is masking its effect. Therefore, epistasis can be related to gene over dominance caused by heterozygosity at specific loci.[2] What this means is that the heterozygote (hybrid) when compared to the homozygote (parent) is better adapted and therefore shows more transgressive, extreme phenotypes. All of these causes lead to the appearance of these extreme phenotypes and creates a hybrid species that will deviate away from the parent species niche and eventually create an individual "hybrid" species.
Environmental
Other than the genetic factors solely causing transgressive segregation, environmental factors can cause genetic factors to take place. Environmental factors that cause transgressive segregation can be influenced by human activity and climate change. Both human activity and climate change have the capability to force species of a specific genome to interact with other species with different genomes.
For example, if a bridge is built that connects two isolated areas to one another, a gene flow door would open. This open door will increase the interactions between different species with different genomes can create hybrid species that can potentially show transgressive phenotypes. Human activity can open the gene flow door by pursuing harmful actions such as cutting down forests and pollution. Climate change on the other hand can open the gene flow door by breaking climate and environmental barriers that were present before. This convergence between species can give rise to a hybrid species that will have more phenotypic variation when compared to the parent species. This increase in phenotypic variation has the potential for transgressive segregation to occur.
Examples of transgressive segregation
In Kenya, there is a fungus called septoria tritici blotch (STB) that diminishes yield in wheat crop. The parent species of wheat had little resistance toward STB, but the hybrid species due to transgressive segregation showed a higher resistance toward STB and therefore a higher fitness. You can create a higher resistance to STB by crossing genes together that are efficient. In result, out of 36 crosses there were 31 that showed a higher mean fitness than the control, parent value. These 31 crosses indicate a higher resistance to STB. The crosses used were from other commercial wheat's that were high yielding which is advantageous because there is a lower chance of deleterious (unwanted traits) appearing and therefore an increase in beneficial traits. Transgressive segregation has been found to be useful to create a resistance toward this organism in order to increase the yield of wheat crop.
Rieseberg used sunflowers to show the transgressive segregation of parental traits. Helianthus annuus and Helianthus petiolaris are the two parent groups for the hybrids. Ultimately there were three hybrid sunflower species. When compared to the fitness of the parents, the hybrids showed a higher tolerance in areas which the parent species would not be able to survive i.e. salt marsh, sand dunes, and deserts. Transgressive segregation allowed these hybrids to survive in areas that the parent would not be able to. Therefore, the hybrids were populated in areas where the parent species were not. This is due to hybrid species showing more gene expression (phenotypes) than their parents and also having some genes that are transgressive (extreme) in nature.
Testing for transgressive segregation
There are many ways to test if transgressive segregation occurred within a population. One common way to test for transgressive segregation is to use a Dunnett's test. This test looks at whether the hybrid species' performance was different from the control group by looking whether or not the mean of the control group (parent species) differs significantly from mean of the other groups. If there is a difference, that is an indication of transgressive segregation. Another commonly used test is the use of quantitative trait loci (QTL) to assess transgressive segregation. Alleles with QTL that were opposed (either by overdomiance or underdominance) of the parental parent QTL indicate that transgressive segregation occurred. Alleles with QTL that was the same as the predicted parent QTL showed that there was no transgressive segregation.
Importance
Transgressive segregation creates an opportunity for new hybrid species to arise that are more fit than their ancestors. As seen with the STB in Kenya and Rieseberg's sunflowers, transgressive segregation can be used to create a species that is more adaptable and resistant in areas where there is environmental stress. Transgressive segregation can be seen as genetic engineering in the way that the goal for each of these events is to create an organism that is more fit than the last.
References
Genetics
Biological evolution | Transgressive segregation | [
"Biology"
] | 1,375 | [
"Genetics"
] |
7,373,637 | https://en.wikipedia.org/wiki/Oblique%20correction | In particle physics, an oblique correction refers to a particular type of radiative correction to the electroweak sector of the Standard Model. Oblique corrections are defined in four-fermion scattering processes, ( + → + ) at the CERN Large Electron–Positron Collider. There are three classes of radiative corrections to these processes: vacuum polarization corrections, vertex corrections, and box corrections. The vacuum polarization corrections are referred to as oblique corrections, since they only affect the mixing and propagation of the gauge bosons and they do not depend on which type of fermions appear in the initial or final states. (The vertex and box corrections, which depend on the identity of the initial and final state fermions, are called nonoblique corrections.)
Any new particles charged under the electroweak gauge groups can contribute to oblique corrections. Therefore, the oblique corrections can be used to constrain possible new physics beyond the Standard Model. To affect the nonoblique corrections, on the other hand, the new particles must couple directly to the external fermions.
The oblique corrections are usually parameterized in terms of the Peskin–Takeuchi parameters S, T, and U.
See also
Initial and final state radiation
References
Standard Model
Physics beyond the Standard Model | Oblique correction | [
"Physics"
] | 266 | [
"Standard Model",
"Unsolved problems in physics",
"Particle physics",
"Particle physics stubs",
"Physics beyond the Standard Model"
] |
7,373,748 | https://en.wikipedia.org/wiki/Nonoblique%20correction | In four-fermion scattering processes of particle physics, a nonoblique correction, also called a direct correction, refers to a radiative correction of type
+ → +
in the electroweak sector of the Standard Model. These corrections are being studied at the CERN LEP collider. Together with the oblique corrections, nonoblique corrections can be used to constrain models of physics beyond the Standard Model.
Classes
There are three classes of radiative corrections to these processes:
vacuum polarization corrections,
vertex corrections, and
box corrections.
The vertex and box corrections, which depend on the identity of the initial and final state fermions, are referred to as the non-oblique corrections. The vacuum polarization corrections are referred to as oblique corrections, since they only affect the mixing and propagation of the gauge bosons and they do not depend on which type of fermions appear in the initial or final states.
Examples
An example of a vertex correction is the nonuniversality (flavor dependence) of the couplings of the quarks and leptons to the charged and neutral weak currents. Another example is the anomalous magnetic dipole moment.
In order to affect the nonoblique corrections, particles must couple directly to the external fermions. Such couplings are expected to be suppressed in most cases, with one exception being the vertex.
See also
Initial and final state radiation
References
Standard Model
Physics beyond the Standard Model | Nonoblique correction | [
"Physics"
] | 299 | [
"Standard Model",
"Unsolved problems in physics",
"Particle physics",
"Particle physics stubs",
"Physics beyond the Standard Model"
] |
7,374,160 | https://en.wikipedia.org/wiki/General%20feature%20format | In bioinformatics, the general feature format (gene-finding format, generic feature format, GFF) is a file format used for describing genes and other features of DNA, RNA and protein sequences.
GFF Versions
The following versions of GFF exist:
General Feature Format Version 2, generally deprecated
Gene Transfer Format 2.2, a derivative used by Ensembl
Generic Feature Format Version 3
Genome Variation Format, with additional pragmas and attributes for sequence_alteration features
GFF2/GTF had a number of deficiencies, notably that it can only represent two-level feature hierarchies and thus cannot handle the three-level hierarchy of gene → transcript → exon. GFF3 addresses this and other deficiencies. For example, it supports arbitrarily many hierarchical levels, and gives specific meanings to certain tags in the attributes field.
The GTF is identical to GFF, version 2.
GFF general structure
All GFF formats (GFF2, GFF3 and GTF) are tab delimited with 9 fields per line. They all share the same structure for the first 7 fields, while differing in the content and format of the ninth field. Some field names have been changed in GFF3 to avoid confusion. For example, the "seqid" field was formerly referred to as "sequence", which may be confused with a nucleotide or amino acid chain. The general structure is as follows:
The 8th field: phase of CDS features
Simply put, CDS means "CoDing Sequence". The exact meaning of the term is defined by Sequence Ontology (SO). According to the GFF3 specification:
Meta Directives
In GFF files, additional meta information can be included and follows after the ## directive. This meta information can detail GFF version, sequence region, or species (full list of meta data types can be found at Sequence Ontology specifications).
GFF software
Servers
Servers that generate this format:
Clients
Clients that use this format:
Validation
The modENCODE project hosts an online GFF3 validation tool with generous limits of 286.10 MB and 15 million lines.
The Genome Tools software collection contains a gff3validator tool that can be used offline to validate and possibly tidy GFF3 files. An online validation service is also available.
See also
Distributed Annotation System
Variant Call Format
Sequence alignment
References
Bioinformatics
Biological sequence format | General feature format | [
"Engineering",
"Biology"
] | 499 | [
"Bioinformatics",
"Biological engineering",
"Biological sequence format"
] |
7,374,187 | https://en.wikipedia.org/wiki/Obstacle%20avoidance | Obstacle avoidance, in robotics, is a critical aspect of autonomous navigation and control systems. It is the capability of a robot or an autonomous system/machine to detect and circumvent obstacles in its path to reach a predefined destination. This technology plays a pivotal role in various fields, including industrial automation, self-driving cars, drones, and even space exploration. Obstacle avoidance enables robots to operate safely and efficiently in dynamic and complex environments, reducing the risk of collisions and damage.
For a robot or autonomous system to successfully navigate through obstacles, it must be able to detect such obstacles. This is most commonly done through the use of sensors, which allow the robot to process its environment, make a decision on what it must do to avoid an obstacle, and carry out that decision with the use of its effectors, or tools that allow a robot to interact with its environment.
Approaches
There are several methods for robots or autonomous machines to carry out their decisions in real-time. Some of these methods include sensor-based approaches, path planning algorithms, and machine learning techniques.
Sensor-based
One of the most common approaches to obstacle avoidance is the use of various sensors, such as ultrasonic, LiDAR, radar, sonar, and cameras. These sensors allow an autonomous machine to do a simple 3 step process: sense, think, and act. They take in inputs of distances in objects and provide the robot with data about its surroundings enabling it to detect obstacles and calculate their distances. The robot can then adjust its trajectory to navigate around these obstacles while maintaining its intended path. All of this is done and carried out in real-time and can be practically and effectively used in most applications of obstacle avoidance
While this method works well under most circumstances, there are such where more advanced techniques could be useful and appropriate for efficiently reaching an endpoint.
Path planning algorithms
Path Planning Algorithms are critical for optimally calculating and routing collision-free paths. These algorithms take into account the robot's position, destination, and the locations of obstacles in the environment. They take and store this information to map out an area, and then use that map to calculate the fastest possible route to a specific destination. Such algorithms are commonly used in routing mazes and autonomous vehicles. Popular path-planning algorithms include A* (A-star), Dijkstra's algorithm, and Rapidly-exploring Random Trees (RRT). These algorithms help the robot find the quickest path to reach its goal while avoiding collisions, all in real time.
Machine learning techniques
With the use of machine learning, the range of possibilities for obstacle avoidance becomes far greater. With artificial intelligence (AI), an autonomous machine can figure out a path to get to its destination, but can also learn to adapt to a rapidly changing environment at the same time. It can do this by being put through many testing stages of exposure to obstacles and environmental changes. By giving an AI a task and reward for doing a task correctly, over time, it can learn to do this task efficiently and effectively. This allows the machine to understand what its obstacles are and to come up with an efficient path around them. It also gives the machine the ability to learn how to deal with specific cases, which can include dealing with water, hills, high winds or temperatures, etc. This use of AI allows the autonomous machine to react accordingly to a plethora of situations that could be expected or unexpected. This form of obstacle avoidance is especially good in autonomous vehicles as it removes possible human errors that can occur.
Applications
Obstacle avoidance can be found in a variety of different fields, including but not limited to:
Autonomous vehicles Vehicles with the ability to drive themselves have been around since the 1980s and have been especially popularized in modern culture due to companies such as Tesla and Nvidia.
Satellites Due to there being debris around Earth's orbit, satellites must be able to avoid such debris. They can do this by detecting and calculating if and when an object will hit the satellite. Once that is done, the satellite can use drag to decelerate and change its trajectory to avoid impact.
Drones Drones can be used autonomously for a variety of reasons, some of which include mail, military, mapping, agriculture, and much more.
Public Transport The rise of autonomous vehicles has also lead to their use for public transports as a cheaper alternative to hiring drivers, while also removing possible human error.
Industrial Systems Large corporations use obstacle avoidance when it comes to their automated industrial systems, which replace the need for workers and reduces the amount of mistakes made.
Challenges
Although these strategies for incorporating obstacle avoidance work, there are challenges to them that still require further development and planning. For one, it's difficult for sensors to quickly take in information on their environment, have the machine process the information, and make a decision about what it has to do to avoid an obstacle when it's moving too fast. This problem is very difficult to fix and if the machine can't act quickly enough, it can lead to the danger or destruction of the machine and any people around it. It is also incredibly difficult to account for every possible obstacle that can get in the way of an autonomous machine. For example, when it comes to satellites, there are millions of pieces of debris in Earth's orbit, so it is difficult to know when one may hit a satellite and from where and when.
References
Control theory
Robot control | Obstacle avoidance | [
"Mathematics",
"Engineering"
] | 1,089 | [
"Robotics engineering",
"Applied mathematics",
"Control theory",
"Robot control",
"Dynamical systems"
] |
7,375,449 | https://en.wikipedia.org/wiki/Rough%20number | A k-rough number, as defined by Finch in 2001 and 2003, is a positive integer whose prime factors are all greater than or equal to k. k-roughness has alternately been defined as requiring all prime factors to strictly exceed k.
Examples (after Finch)
Every odd positive integer is 3-rough.
Every positive integer that is congruent to 1 or 5 mod 6 is 5-rough.
Every positive integer is 2-rough, since all its prime factors, being prime numbers, exceed 1.
See also
Buchstab function, used to count rough numbers
Smooth number
Notes
References
Finch's definition from Number Theory Archives
"Divisibility, Smoothness and Cryptographic Applications", D. Naccache and I. E. Shparlinski, pp. 115–173 in Algebraic Aspects of Digital Communications, eds. Tanush Shaska and Engjell Hasimaj, IOS Press, 2009, .
The On-Line Encyclopedia of Integer Sequences (OEIS)
lists p-rough numbers for small p:
2-rough numbers: A000027
3-rough numbers: A005408
5-rough numbers: A007310
7-rough numbers: A007775
11-rough numbers: A008364
13-rough numbers: A008365
17-rough numbers: A008366
19-rough numbers: A166061
23-rough numbers: A166063
Integer sequences | Rough number | [
"Mathematics"
] | 302 | [
"Sequences and series",
"Integer sequences",
"Mathematical structures",
"Number theory stubs",
"Recreational mathematics",
"Mathematical objects",
"Combinatorics",
"Numbers",
"Number theory"
] |
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