id int64 580 79M | url stringlengths 31 175 | text stringlengths 9 245k | source stringlengths 1 109 | categories stringclasses 160 values | token_count int64 3 51.8k |
|---|---|---|---|---|---|
42,054,240 | https://en.wikipedia.org/wiki/Metreleptin | Metreleptin, sold under the brand name Myalept among others, is a synthetic analog of the hormone leptin used to treat various forms of dyslipidemia. It has been approved in Japan for metabolic disorders including lipodystrophy and in the United States as replacement therapy to treat the complications of leptin deficiency, in addition to diet, in patients with congenital generalized or acquired generalized lipodystrophy.
The most common side effects include hypoglycaemia (low blood glucose) and weight loss.
It was approved for medical use in Canada in January 2024.
Medical uses
In the European Union, metreleptin is indicated in addition to diet to treat lipodystrophy, where people have a loss of fatty tissue under the skin and a build-up of fat elsewhere in the body such as in the liver and muscles. It is used in adults and children above the age of two years with generalised lipodystrophy (Berardinelli-Seip syndrome and Lawrence syndrome); and in adults and children above the age of twelve years with partial lipodystrophy (including Barraquer-Simons syndrome), when standard treatments have failed.
In the United States, it is indicated as an adjunct to diet as replacement therapy to treat the complications of leptin deficiency in people with congenital or acquired generalized lipodystrophy.
Research
Metreleptin is being investigated for the treatment of diabetes and/or hypertriglyceridemia, in patients with rare forms of lipodystrophy, syndromes characterized by abnormalities in adipose tissue distribution, and severe metabolic abnormalities. The FDA approved Metreleptin injection for treating complications of leptin deficiency in February 2014.
In a three-year study of metreleptin in patients with lipodystrophy organized by the National Institute of Diabetes and Digestive and Kidney Diseases at the National Institutes of Health, metreleptin treatment was associated with a significant decrease in blood glucose (A1c decreased from 9.4% at baseline to 7.0% at study end) and triglyceride concentration (from 500 mg/dl at baseline to 200 mg/dl at study end). Metreleptin is effective in most patients with generalized lipodystrophy where circulating leptin levels are extremely low. Analogous to insulin replacement for patients with type 1 Diabetes, metreleptin restores the function of a deficient hormone. However, in patients with partial lipodystrophy where there is only a relative leptin deficiency, the response to metreleptin is not universal. This may or may not be due to anti-leptin antibodies.
Metreleptin is undergoing research for its potential benefit in the treatment of anorexia nervosa. It is hypothesized that the gradual loss of body fat mass, and more specifically the ensuing low leptin levels, escalate the preexisting drive for thinness into an obsessive-compulsive-like and addictive-like state. It was shown that short-term metreleptin treatment of patients with anorexia nervosa had rapid on-set of beneficial cognitive, emotional, and behavioral effects. Among other things, depression, drive for activity, repetitive thoughts of food, inner restlessness, and weight phobia decreased rapidly. Whether metreleptin (or another leptin analogue) is a suitable treatment for anorexia nervosa remains to be seen. Potential side effects are weight loss and the development of anti-metreleptin antibodies.
In a clinical study, metreleptin treatment improved non-alcoholic steatohepatitis (fatty liver disease) both in patients with partial lipodystrophy and in those with relative leptin deficiency. Both steatosis and hepatic injury scores decreased. Metreleptin reduces body weight in overweight people with low leptin levels.
Although it is not very effective as a weight loss drug, leptin levels are lowered in people who have lost weight and it is hypothesized that supplemental leptin could help them with weight loss maintenance. However, there is no regulatory pathway for drug approval for this indication.
References
Leptin receptor agonists
Systemic hormonal preparations
Drugs developed by AstraZeneca
Orphan drugs
Pharmacology | Metreleptin | Chemistry | 908 |
41,062 | https://en.wikipedia.org/wiki/Double-ended%20synchronization | For two connected exchanges in a communications network, a double-ended synchronization (also called double-ended control) is a synchronization control scheme in which the phase error signals used to control the clock at one telephone exchange are derived by comparison with the phase of the incoming digital signal and the phase of the internal clocks at both exchanges.
References
Telecommunications techniques
Synchronization | Double-ended synchronization | Engineering | 80 |
26,633,993 | https://en.wikipedia.org/wiki/One-male%20group | One-male groups are a type of social organization where one male interacts with a group of females and their immature offspring. Offspring of both sexes are evicted from the group upon reaching puberty. It can be seen in many species of primates, including the gelada baboon, the patas monkey, savanna baboon, sun-tailed monkey, golden snub-nosed monkey, and the hamadryas baboon. There are costs and benefits for individuals living in one-male groups. As well, individuals within one-male groups can interact with each other just like individuals can interact with those from different one-male groups.
Origin
A study of savanna baboons (hamadryas ursinus) indicates that the one-male groups in this species are formed by fissioning. For example, a 100-month old male entered a multi male - multi female (mm) group then formed a one-male group with eight of the adult females in the MM group. Juveniles of the species, suspected to be young of the eight adult females, also joined the new one-male group. However, when a new male successfully enters a one-male group, the social hierarchy will be changed depending on the previously determined rankings of the newly entered male. The previous resident male of the one-male group may be out-ranked and therefore placed lower on the hierarchy of males.
Costs
Infanticide
One of the costs of living in one-male groups is the killing of unweaned young by conspecific adult males. This is known as infanticide, and mostly occurs when adult males or coalitions of males takeover the group and kill the resident male. This is done to increase the reproductive success of the intervening males because the females are more likely to mate with them now that they need to produce new offspring. While the infanticide is an obvious cost to females, it is beneficial to the infanticidal males. Infanticide in one-male groups has been studied in the Virungas population of mountain gorillas.
Inbreeding
Another cost of living in one-male social groups is that there is a high occurrence of inbreeding. This means that closely related individuals can mate and produce offspring. This results in decreasing genetic diversity with subsequent generations of the species. For example, inbreeding has been studied in one-male groups of sun-tailed monkeys (Cercopithecus solatus). In this study, the time between two births for females increased when an inbred offspring was born. This suggests that there could be increased maternal costs with giving birth to and rearing an inbred offspring, compared to a noninbred offspring. Inbreeding depression resulted from the decreased genetic diversity within this population, meaning that the population as a whole experienced a decrease in fitness (i.e. reproductive success). Unlike infanticide, the high occurrence of inbreeding in one-male groups is a disadvantageous to both the females and males in the group.
Benefits
Feeding advantages
Experiments involving the hamadryas baboon species (hamadryas hamadryas) provide evidence of feeding advantages for male and female members of one-male groups. However, the findings of feeding advantages were only evident when these one-male groups formed clans. It has been shown that males from single one-male groups did not approach males that were part of clans to compete for food sources. Additionally, it was found that males from smaller clans did not approach males from bigger clans (i.e. with more one-male groups) to compete for food. Ultimately, these feeding advantages of decreased competition were seen between one-male groups, not for males within the same groups or clans. In addition, it can be said that males and females in a clan have feeding advantages compared to males and females in single one-male groups because it has been shown that the males and females in clans gain access to clumped food sources earlier than those in single one-male groups and that they spend more time with clumped food sources than the single groups.
Within-group interactions
Female-female interactions
Studies of social interactions among golden snub‐nosed monkeys (Rhinopithecus roxellana) reveal that adult females tend to interact with each other, but they do not form strong social bonds with other females in the same one-male group.
Female-male interactions
It has been shown that adult female golden snub-nosed monkeys do not form strong social relationships with the resident male in the one-male group. However, the adult females tended to interact more with other adult females instead of the resident male when they were looking for social interaction.
Patterns of social relationships
While researchers have found that individuals in one-male groups of hamadryas baboons exhibit a pattern of social relationships called a star-shaped relationship, it has been found that gelada baboon (Theropithecus gelada) individuals in one-male groups exhibit a net-shaped relationship pattern. Individuals in the snub-nosed monkey species exhibit a different pattern of social relationships than the two other baboon species.
Between-group interactions
Allomaternal nursing
In a study of social relationships among a clan (i.e. multiple one-male groups) of Yunnan snub-nosed monkeys (Rhinopithecus bieti), it was determined that the adult females of one-male groups sometimes care for the young of other one-male groups. For example, when a mother and her young offspring were accidentally separated, a mother belonging to a different one-male group cared for the young. The separated young was nursed by the adoptive mother (who also nursed her own offspring) and tolerated by the resident male of the one-male group that the offspring was now temporarily a part of.
Affiliative interactions
Affiliative interactions between individuals of one-male groups include sitting near, grooming in front of, and handling the infants of other one-male groups. The most prevalent type of affiliative interaction seen in a study involving Sichuan snub-nosed monkeys (Rhinopithecus roxellana) is infant handling. This infant handling can form gatherings of multiple one-male units that forage together. This type of social structure is called a band.
See also
Multi-male group
References
Ethology | One-male group | Biology | 1,301 |
3,677,332 | https://en.wikipedia.org/wiki/Paraxanthine | Paraxanthine, also known as 1,7-dimethylxanthine, is an isomer of theophylline and theobromine, two well-known stimulants found in coffee, tea, and chocolate mainly in the form of caffeine. It is a member of the xanthine family of alkaloids, which includes theophylline, theobromine and caffeine.
Production and metabolism
Paraxanthine is not known to be produced by plants but is observed in nature as a metabolite of caffeine in animals and some species of bacteria.
Paraxanthine is the primary metabolite of caffeine in humans and other animals, such as mice. Shortly after ingestion, roughly 84% of caffeine is metabolized into paraxanthine by hepatic cytochrome P450, which removes a methyl group from the N3 position of caffeine. After formation, paraxanthine can be broken down to 7-methylxanthine by demethylation of the N1 position, which is subsequently demethylated into xanthine or oxidized by CYP2A6 and CYP1A2 into 1,7-dimethyluric acid. In another pathway, paraxanthine is broken down into 5-acetylamino-6-formylamino-3-methyluracil through N-acetyl-transferase 2, which is then broken down into 5-acetylamino-6-amino-3-methyluracil by non-enzymatic decomposition. In yet another pathway, paraxanthine is metabolized CYPIA2 forming 1-methyl-xanthine, which can then be metabolized by xanthine oxidase to form 1-methyl-uric acid.
Certain proposed synthetic pathways of caffeine make use of paraxanthine as a bypass intermediate. However, its absence in plant alkaloid assays implies that these are infrequently, if ever, directly produced by plants.
Pharmacology and physiological effects
Like caffeine, paraxanthine is a psychoactive central nervous system (CNS) stimulant.
Pharmacodynamics
Studies indicate that, similar to caffeine, simultaneous antagonism of adenosine receptors is responsible for paraxanthine's stimulatory effects. Paraxanthine adenosine receptor binding affinity (21 μM for A1, 32 μM for A2A, 4.5 μM for A2B, and >100 for μM for A3) is similar or slightly stronger than caffeine, but weaker than theophylline.
Paraxanthine is a selective inhibitor of cGMP-preferring phosphodiesterase (PDE9) activity and is hypothesized to increase glutamate and dopamine release by potentiating nitric oxide signaling. Activation of a nitric oxide-cGMP pathway may be responsible for some of the behavioral effects of paraxanthine that differ from those associated with caffeine.
Paraxanthine is a competitive nonselective phosphodiesterase inhibitor which raises intracellular cAMP, activates PKA, inhibits TNF-alpha and leukotriene synthesis, and reduces inflammation and innate immunity.
Unlike caffeine, paraxanthine acts as an enzymatic effector of Na+/K+ ATPase. As a result, it is responsible for increased transport of potassium ions into skeletal muscle tissue. Similarly, the compound also stimulates increases in calcium ion concentration in muscle.
Pharmacokinetics
The pharmacokinetic parameter for paraxanthine are similar to those for caffeine, but differ significantly from those for theobromine and theophylline, the other major caffeine-derived methylxanthine metabolites in humans (Table 1).
Uses
Paraxanthine is a phosphodiesterase type 9 (PDE9) inhibitor and it is sold as a research molecule for this same purpose.
Toxicity
Paraxanthine is believed to exhibit a lower toxicity than caffeine and the caffeine metabolite, theophylline. In a mouse model, intraperitoneal paraxanthine doses of 175 mg/kg/day did not result in animal death or overt signs of stress; by comparison, the intraperitoneal LD50 for caffeine in mice is reported at 168 mg/kg. In in vitro cell culture studies, paraxanthine is reported to be less harmful than caffeine and the least harmful of the caffeine-derived metabolites in terms of hepatocyte toxicity.
As with other methylxanthines, paraxanthine is reported to be teratogenic when administered in high doses; but it is a less potent teratogen as compared to caffeine and theophylline. A mouse study on the potentiating effects of methylxanthines coadministered with mitomycin C on teratogenicity reported the incidence of birth defects for caffeine, theophylline, and paraxanthine to be 94.2%, 80.0%, and 16.9%, respectively; additionally, average birth weight decreased significantly in mice exposed to caffeine or theophylline when coadministered with mitomycin C, but not for paraxanthine coadministered with mitomycin C.
Paraxanthine was reported to be significantly less clastogenic compared to caffeine or theophylline in an in vitro study using human lymphocytes.
References
External links
Adenosine receptor antagonists
Animal metabolites
Human drug metabolites
Phosphodiesterase inhibitors
Stimulants
Wakefulness-promoting agents
Xanthines | Paraxanthine | Chemistry | 1,236 |
13,276,879 | https://en.wikipedia.org/wiki/Racetrack%20memory | Racetrack memory or domain-wall memory (DWM) is an experimental non-volatile memory device under development at IBM's Almaden Research Center by a team led by physicist Stuart Parkin. It is a current topic of active research at the Max Planck Institute of Microstructure Physics in Dr. Parkin's group. In early 2008, a 3-bit version was successfully demonstrated. If it were to be developed successfully, racetrack memory would offer storage density higher than comparable solid-state memory devices like flash memory.
Description
Racetrack memory uses a spin-coherent electric current to move magnetic domains along a nanoscopic permalloy wire about 200 nm across and 100 nm thick. As current is passed through the wire, the domains pass by magnetic read/write heads positioned near the wire, which alter the domains to record patterns of bits. A racetrack memory device is made up of many such wires and read/write elements. In general operational concept, racetrack memory is similar to the earlier bubble memory of the 1960s and 1970s. Delay-line memory, such as mercury delay lines of the 1940s and 1950s, are a still-earlier form of similar technology, as used in the UNIVAC and EDSAC computers. Like bubble memory, racetrack memory uses electrical currents to "push" a sequence of magnetic domains through a substrate and past read/write elements. Improvements in magnetic detection capabilities, based on the development of spintronic magnetoresistive sensors, allow the use of much smaller magnetic domains to provide far higher bit densities.
In production, it was expected that the wires could be scaled down to around 50 nm. There were two arrangements considered for racetrack memory. The simplest was a series of flat wires arranged in a grid with read and write heads arranged nearby. A more widely studied arrangement used U-shaped wires arranged vertically over a grid of read/write heads on an underlying substrate. This would allow the wires to be much longer without increasing its 2D area, although the need to move individual domains further along the wires before they reach the read/write heads results in slower random access times. Both arrangements offered about the same throughput performance. The primary concern in terms of construction was practical; whether or not the three dimensional vertical arrangement would be feasible to mass-produce.
Comparison to other memory devices
Projections in 2008 suggested that racetrack memory would offer performance on the order of 20-32 ns to read or write a random bit. This compared to about 10,000,000 ns for a hard drive, or 20-30 ns for conventional DRAM. The primary authors discussed ways to improve the access times with the use of a "reservoir" to about 9.5 ns. Aggregate throughput, with or without the reservoir, would be on the order of 250-670 Mbit/s for racetrack memory, compared to 12800 Mbit/s for a single DDR3 DRAM, 1000 Mbit/s for high-performance hard drives, and 1000 to 4000 Mbit/s for flash memory devices. The only current technology that offered a clear latency benefit over racetrack memory was SRAM, on the order of 0.2 ns, but at a higher cost. Larger feature size "F" of about 45 nm (as of 2011) with a cell area of about 140 F2.
Racetrack memory is one among several emerging technologies that aim to replace conventional memories such as DRAM and Flash, and potentially offer a universal memory device applicable to a wide variety of roles. Other contenders included magnetoresistive random-access memory (MRAM), phase-change memory (PCRAM) and ferroelectric RAM (FeRAM). Most of these technologies offer densities similar to flash memory, in most cases worse, and their primary advantage is the lack of write-endurance limits like those in flash memory. Field-MRAM offers excellent performance as high as 3 ns access time, but requires a large 25-40 F² cell size. It might see use as an SRAM replacement, but not as a mass storage device. The highest densities from any of these devices is offered by PCRAM, with a cell size of about 5.8 F², similar to flash memory, as well as fairly good performance around 50 ns. Nevertheless, none of these can come close to competing with racetrack memory in overall terms, especially density. For example, 50 ns allows about five bits to be operated in a racetrack memory device, resulting in an effective cell size of 20/5=4 F², easily exceeding the performance-density product of PCM. On the other hand, without sacrificing bit density, the same 20 F² area could fit 2.5 2-bit 8 F² alternative memory cells (such as resistive RAM (RRAM) or spin-torque transfer MRAM), each of which individually operating much faster (~10 ns).
In most cases, memory devices store one bit in any given location, so they are typically compared in terms of "cell size", a cell storing one bit. Cell size itself is given in units of F², where "F" is the feature size design rule, representing usually the metal line width. Flash and racetrack both store multiple bits per cell, but the comparison can still be made. For instance, hard drives appeared to be reaching theoretical limits around 650 nm²/bit, defined primarily by the capability to read and write to specific areas of the magnetic surface. DRAM has a cell size of about 6 F², SRAM is much less dense at 120 F². NAND flash memory is currently the densest form of non-volatile memory in widespread use, with a cell size of about 4.5 F², but storing three bits per cell for an effective size of 1.5 F². NOR flash memory is slightly less dense, at an effective 4.75 F², accounting for 2-bit operation on a 9.5 F² cell size. In the vertical orientation (U-shaped) racetrack, nearly 10-20 bits are stored per cell, which itself would have a physical size of at least about 20 F². In addition, bits at different positions on the "track" would take different times (from ~10 to ~1000 ns, or 10 ns/bit) to be accessed by the read/write sensor, because the "track" would move the domains at a fixed rate of ~100 m/s past the read/write sensor.
Development challenges
One limitation of the early experimental devices was that the magnetic domains could be pushed only slowly through the wires, requiring current pulses on the orders of microseconds to move them successfully. This was unexpected, and led to performance equal roughly to that of hard drives, as much as 1000 times slower than predicted. Recent research has traced this problem to microscopic imperfections in the crystal structure of the wires which led to the domains becoming "stuck" at these imperfections. Using an X-ray microscope to directly image the boundaries between the domains, their research found that domain walls would be moved by pulses as short as a few nanoseconds when these imperfections were absent. This corresponds to a macroscopic performance of about 110 m/s.
The voltage required to drive the domains along the racetrack would be proportional to the length of the wire. The current density must be sufficiently high to push the domain walls (as in electromigration). A difficulty for racetrack technology arises from the need for high current density (>108 A/cm2); a 30 nm x 100 nm cross-section would require >3 mA. The resulting power draw becomes higher than that required for other memories, e.g., spin-transfer torque memory (STT-RAM) or flash memory.
Another challenge associated with racetrack memory is the stochastic nature in which the domain walls move, i.e., they move and stop at random positions. There have been attempts to overcome this challenge by producing notches at the edges of the nanowire. Researchers have also proposed staggered nanowires to pin the domain walls precisely. Experimental investigations have shown the effectiveness of staggered domain wall memory. Recently researchers have proposed non-geometrical approaches such as local modulation of magnetic properties through composition modification. Techniques such as annealing induced diffusion and ion-implantation are used.
See also
Giant magnetoresistance (GMR) effect
Magnetoresistive random-access memory (MRAM)
Spintronics
Spin transistor
References
External links
Redefining the Architecture of Memory
IBM Moves Closer to New Class of Memory (YouTube video)
IBM Racetrack Memory Project
Computer memory
Non-volatile memory
IBM storage devices
Spintronics | Racetrack memory | Physics,Materials_science | 1,757 |
26,165,831 | https://en.wikipedia.org/wiki/HD%20129445%20b | HD 129445 b is an eccentric Jupiter gas giant exoplanet orbiting the star HD 129445 which was discovered by the Magellan Planet Search Program in 2010. Its minimum mass is 1.6 times Jupiter's, and it takes 5 years to complete one orbit around HD 129445, a G-type star approximately 219 light years away. In 2023, the inclination and true mass of HD 129445 b were determined via astrometry.
References
Exoplanets discovered in 2010
Exoplanets detected by radial velocity
Giant planets
Circinus
Exoplanets detected by astrometry | HD 129445 b | Astronomy | 125 |
61,956,186 | https://en.wikipedia.org/wiki/Consumer%20green%20energy%20program | A consumer green energy program is a program that enables households to buy energy from renewable sources. By allowing consumers to purchase renewable energy, it simultaneously diverts the utilization of fossil fuels and promotes the use of renewable energy sources such as solar and wind.
In several countries with common carrier arrangements, electricity retailing arrangements make it possible for consumers to purchase "green" electricity from either their utility or a green power provider. Electricity is considered to be green if it is produced from a source that produces relatively little pollution, and the concept is often considered equivalent to renewable energy. Although electricity is the most common green energy, biomethane is sold as "green gas" in some locations.
In many countries, green energy currently provides a very small amount of electricity, generally contributing less than 2 to 5% to the overall pool of electricity offered by most utility companies, electric companies, or state power pools. In some U.S. states, local governments have formed regional power purchasing pools using Community Choice Aggregation and Solar Bonds to achieve a 51% renewable mix or higher, such as in the City of San Francisco.
By participating in a green energy program a consumer may be having an effect on the energy sources used and ultimately might be helping to promote and expand the use of green energy. They are also making a statement to policy makers that they are willing to pay a price premium to support renewable energy. Green energy consumers either obligate the utility companies to increase the amount of green energy that they purchase from the pool (so decreasing the amount of non-green energy they purchase), or directly fund the green energy through a green power provider. If insufficient green energy sources are available, the utility must develop new ones or contract with a third party energy supplier to provide green energy, causing more to be built. However, there is no way the consumer can check whether or not the electricity bought is "green" or otherwise.
In some countries such as the Netherlands, electricity companies guarantee to buy an equal amount of 'green power' as is being used by their green power customers. The Dutch government exempts green power from pollution taxes, which means green power is hardly any more expensive than other power.
Green energy and labeling by region
European Union
Directive 2004/8/EC of the European Parliament and of the Council of 11 February 2004 on the promotion of cogeneration based on a useful heat demand in the internal energy market includes the article 5 (Guarantee of origin of electricity from high-efficiency cogeneration).
European environmental NGOs have launched an ecolabel for green power. The ecolabel is called EKOenergy. It sets criteria for sustainability, additionality, consumer information and tracking. Only part of electricity produced by renewables fulfills the EKOenergy criteria.
United Kingdom
The Green Energy Supply Certification Scheme was launched in 2010: it implements guidelines from the Energy Regulator, Ofgem, and sets requirements on transparency, the matching of sales by renewable energy supplies, and additionality. Green electricity in the United Kingdom is widespread, and green gas is supplied to over a million homes.
United States
The United States Department of Energy (DOE), the Environmental Protection Agency (EPA), and the Center for Resource Solutions (CRS) recognizes the voluntary purchase of electricity from renewable energy sources (also called renewable electricity or green electricity) as green power.
The most popular way to purchase renewable energy as revealed by NREL data is through purchasing Renewable Energy Certificates (RECs). According to a Natural Marketing Institute (NMI) survey 55 percent of American consumers want companies to increase their use of renewable energy.
DOE selected six companies for its 2007 Green Power Supplier Awards, including Constellation NewEnergy; 3Degrees; Sterling Planet; SunEdison; Pacific Power and Rocky Mountain Power; and Silicon Valley Power. The combined green power provided by those six winners equals more than 5 billion kilowatt-hours per year, which is enough to power nearly 465,000 average U.S. households. In 2014, Arcadia Power made RECS available to homes and businesses in all 50 states, allowing consumers to use "100% green power" as defined by the EPA's Green Power Partnership.
The U.S. Environmental Protection Agency (USEPA) Green Power Partnership is a voluntary program that supports the organizational procurement of renewable electricity by offering expert advice, technical support, tools and resources. This can help organizations lower the transaction costs of buying renewable power, reduce carbon footprint, and communicate its leadership to key stakeholders.
Throughout the country, more than half of all U.S. electricity customers now have an option to purchase some type of green power product from a retail electricity provider. Roughly one-quarter of the nation's utilities offer green power programs to customers, and voluntary retail sales of renewable energy in the United States totaled more than 12 billion kilowatt-hours in 2006, a 40% increase over the previous year.
In the United States, one of the main problems with purchasing green energy through the electrical grid is the current centralized infrastructure that supplies the consumer's electricity. This infrastructure has led to increasingly frequent brown outs and black outs, high CO2 emissions, higher energy costs, and power quality issues. An additional $450 billion will be invested to expand this fledgling system over the next 20 years to meet increasing demand. In addition, this centralized system is now being further overtaxed with the incorporation of renewable energies such as wind, solar, and geothermal energies. Renewable resources, due to the amount of space they require, are often located in remote areas where there is a lower energy demand. The current infrastructure would make transporting this energy to high demand areas, such as urban centers, highly inefficient and in some cases impossible. In addition, despite the amount of renewable energy produced or the economic viability of such technologies only about 20 percent will be able to be incorporated into the grid. To have a more sustainable energy profile, the United States must move towards implementing changes to the electrical grid that will accommodate a mixed-fuel economy.
Several initiatives are being proposed to mitigate distribution problems. First and foremost, the most effective way to reduce USA's CO2 emissions and slow global warming is through conservation efforts. Opponents of the current US electrical grid have also advocated for decentralizing the grid. This system would increase efficiency by reducing the amount of energy lost in transmission. It would also be economically viable as it would reduce the amount of power lines that will need to be constructed in the future to keep up with demand. Merging heat and power in this system would create added benefits and help to increase its efficiency by up to 80-90%. This is a significant increase from the current fossil fuel plants which only have an efficiency of 34%.
Asia
India
India's Ministry of Power notified 'Green Energy Open Access' Rules to accelerate ambitious renewable energy programmes by enabling provisions to incentivize the common consumers to get Green Power at reasonable rates
through Electricity (Promoting Renewable Energy Through Green Energy Open Access) Rules, 2022 on 06.06.2022
Small-scale green energy systems
Those not satisfied with the third-party grid approach to green energy via the power grid can install their own locally based renewable energy system. Renewable energy electrical systems from solar to wind to even local hydro-power in some cases, are some of the many types of renewable energy systems available locally. Additionally, for those interested in heating and cooling their dwelling via renewable energy, geothermal heat pump systems that tap the constant temperature of the earth, which is around 7 to 15 degrees Celsius a few feet underground and increases dramatically at greater depths, are an option over conventional natural gas and petroleum-fueled heat approaches. Also, in geographic locations where the Earth's Crust is especially thin, or near volcanoes (as is the case in Iceland) there exists the potential to generate even more electricity than would be possible at other sites, thanks to a more significant temperature gradient at these locales.
The advantage of this approach in the United States is that many states offer incentives to offset the cost of installation of a renewable energy system. In California, Massachusetts and several other U.S. states, a new approach to community energy supply called Community Choice Aggregation has provided communities with the means to solicit a competitive electricity supplier and use municipal revenue bonds to finance development of local green energy resources. Individuals are usually assured that the electricity they are using is actually produced from a green energy source that they control. Once the system is paid for, the owner of a renewable energy system will be producing their own renewable electricity for essentially no cost and can sell the excess to the local utility at a profit.
In household power systems, organic matter such as cow dung and spoilable organic matter can be converted to biochar. To eliminate emissions, carbon capture and storage is then used.
References
Sustainable energy
Emissions reduction | Consumer green energy program | Chemistry | 1,788 |
1,619,958 | https://en.wikipedia.org/wiki/Transportation%20Safety%20Board%20of%20Canada | The Transportation Safety Board of Canada (TSB, ), officially the Canadian Transportation Accident Investigation and Safety Board () is the agency of the Government of Canada responsible for advancing transportation safety in Canada. It is accountable to Parliament directly through the President of the King’s Privy Council and the Minister of Intergovernmental and Northern Affairs and Internal Trade. The independent agency investigates accidents and makes safety recommendations in four modes of transportation: aviation, rail, marine and pipelines.
Agency history
Prior to 1990, Transport Canada's Aircraft Accident Investigation Branch (1960–1984) and its successor the Canadian Aviation Safety Board or CASB (1984–1990) were responsible for investigation of air incidents. Before 1990, investigations and actions were taken by Transport Canada and even after 1984 the findings from CASB were not binding for Transport Canada to respond to.
The TSB was created under the Canadian Transportation Accident Investigation and Safety Board Act, which received royal assent in June 1989 and came into force March 29, 1990. It was formed in response to a number of high-profile accidents, following which the Government of Canada identified the need for an independent, multi-modal investigation agency. The headquarters are located in Place du Centre in Gatineau, Quebec.
The provisions of the Canadian Transportation Accident Investigation and Safety Board Act were written to establish an independent relationship between the agency and the Government of Canada.
This agency's first major test came with the crash of Swissair Flight 111 on September 2, 1998, the largest single aviation accident on Canadian territory since the 1985 crash of Arrow Air Flight 1285R. The TSB delivered its report on the accident on March 27, 2003, some 4½ years after the accident and at a cost of $57 million, making it the most complex and costly accident investigation in Canadian history to that date.
From 2005 to 2010, the TSB concluded a number of investigations into high-profile accidents, including:
the crash of Air France Flight 358;
the Cheakamus River derailment;
the sinking of Queen of the North;
the loss overboard of a crewmember of Picton Castle;
the Burnaby pipeline rupture;
the crash of Cougar Helicopters Flight 91;
the sinking of Concordia.
To increase the uptake of its recommendations and address accident patterns, the TSB launched its Watchlist in 2010, which points to nine critical safety issues troubling Canada's transportation system.
On 3 December 2013, in the wake of the Lac-Mégantic rail disaster the previous July, it was reported that the number of runaway trains was triple the number documented by the TSB.
In August 2014, the TSB released the report on its investigation into the July 2013 Lac-Mégantic derailment. In a news conference, then TSB chair Wendy Tadros described how eighteen factors played a role in the disaster including a "weak safety culture" at the now-defunct Montreal, Maine & Atlantic Railways with "a lack of standards, poor training and easily punctured tanks." The TSB also blamed Transport Canada, the regulator, for not doing thorough safety audits often enough on railways "to know how those companies were really managing, or not managing, risk." The TSB report called for "physical restraints, such as wheel chocks, for parked trains." Prior to the accident TSB had called for "new and more robust wagons for flammable liquids" but as of August 2014, little progress had been made in implementing this.
On February 4, 2019, the TSB deployed to the derailment of Canadian Pacific Railway (CP) train 301-349. Ninety-nine cars and two locomotives derailed at Mile 130.6 of the CP Laggan Subdivision, near Field, British Columbia (BC) while proceeding westward to Vancouver, BC. The three train crewmembers – a locomotive engineer, a conductor, and a conductor trainee – died as a result.
During the course of its investigation into the derailment, the organization issued two safety advisories on April 11, 2019 to Transport Canada . The first called attention to the need for effective safety procedures to be applied to all trains stopped in emergency on both "heavy grades" and "mountain grades" and the second highlighted the need to review the efficacy of the inspection and maintenance procedures for grain hopper cars used in CP's unit grain train operations (and for other railways as applicable), and ensure that these cars can be operated safely at all times.
In January 2020, the Senior Investigator was reassigned in order to protect the integrity and objectivity of the investigation after voicing an opinion implying civil or criminal liability. The TSB labelled the comments made to The Fifth Estate journalists as "completely inappropriate" as the mandate of the TSB is to make findings as to causes and contributing factors of a transportation occurrence, but not to assign fault or determine civil or criminal liability. The CBC documentary pointed out what seemed to be a problem, where the private police service of CP Rail investigated the accident. A CPPS officer was also resigned over these circumstances. As of June 2020, the investigation is ongoing.
Mandate and direction
The Transportation Safety Board's mandate is to
conduct independent investigations, including public inquiries when necessary, into selected transportation occurrences in order to make findings as to their causes and contributing factors;
identify safety deficiencies, as evidenced by transportation occurrences;
make recommendations designed to eliminate or reduce any such safety deficiencies; and
report publicly on its investigations and on the related findings
The TSB may assist other transportation safety boards in their investigations. This may happen when:
an incident or accident occurs involving a Canadian-registered aircraft in commercial or air transport use;
an incident or accident occurs involving a Canadian-built aircraft (or an aircraft with Canadian-built engines, propellers, or other vital components) in commercial or air transport use;
a country without the technical ability to conduct a full investigation asks for the TSB's assistance (especially in the field of reading and analyzing the content of flight recorders).
Provincial and territorial governments may call upon the TSB to investigate occurrences. However, it is up to the TSB whether or not to proceed with an investigation. Public reports are published following class one, class two, class three and class four investigations. Recommendations made by the TSB are not legally binding upon the Government of Canada, nor any of its Ministers of departments. However, when a recommendation is made to a federal department, a formal response must be presented to the TSB within 90 days.
The TSB reports to the Parliament of Canada through the President of the King's Privy Council for Canada.
Board membership
As of August 2024, the Board was composed of the following four members:
Chair Yoan Marier
Ken Potter
Paul Dittmann
Leo Donatti
Facilities
The TSB Engineering Laboratory, which has the facilities for investigating transport accidents and incidents, is in Ottawa, adjacent to Ottawa International Airport.
List of chairs
John W. Stants 1990–1996
Benoît Bouchard 1996–2001
Charles H. Simpson 2001–2002 (acting)
Camille Thériault 2002–2004
Charles H. Simpson 2004–2005 (acting)
Wendy A. Tadros 2005–2006 (acting)
Wendy A. Tadros 2006–2014
Kathleen Fox 2014–2024
Yoan Marier 2024–present
See also
Aviation safety
References
External links
Rail accident investigators
Organizations investigating aviation accidents and incidents
Aviation authorities
Transport safety organizations
Federal departments and agencies of Canada
Aviation in Canada
1990 establishments in Quebec
History of transport in Canada
Railway safety
Organizations based in Gatineau
Transport organizations based in Canada
Canadian transport law | Transportation Safety Board of Canada | Technology | 1,531 |
38,462,710 | https://en.wikipedia.org/wiki/LRLL%2054361 | LRLL 54361 also known as L54361 is thought to be a binary protostar producing strobe-like flashes, located in the constellation Perseus in the star-forming region IC 348 and 950 light-years away.
The object may offer insight into a star's early stages of formation, when large masses of gas and dust are falling into a newly forming binary star - called a pulsed accretion model. LRLL 54361 emits a burst of light at regular intervals of 25.34 days, increasing in infrared luminosity by an order of magnitude over a span of a week and then gradually dimming until the next pulse. This behavior be caused by repeated close approaches between the two component stars which are gravitationally linked in an eccentric orbit. The flashes may be the result of large amounts of matter falling into the growing protostars. Since the stars are obscured by the dense disk and envelope of dust surrounding them, direct observation is difficult. This process of star birth has been witnessed in its later stages, but has to date not been seen in such a young system, nor with such intensity and regularity. The pair of stars are thought to be only a few hundred thousand years old.
LRLL 54361 was first detected by the Spitzer Space Telescope as a variable object inside the star-forming region IC 348. The Hubble Space Telescope confirmed the Spitzer observations and revealed the detailed structure around the protostar. Hubble images show two large, clear-swept regions in the disk around the stars. The monitoring of LRLL 54361 continues using other instruments, including the Herschel Space Telescope, and astronomers hope to obtain more direct measurements of the binary star and its orbit.
References
Perseus (constellation)
Protostars | LRLL 54361 | Astronomy | 368 |
66,122,548 | https://en.wikipedia.org/wiki/Polymateria | Polymateria Ltd is a British technology company developing biodegradable plastic alternatives. In 2020, the privately owned company was the first to achieve certified biodegradation of the most commonly-littered forms of plastic packaging in real-world conditions, in less than a year without creating microplastics.
History
Polymateria was founded in 2015 at Imperial College London by Jonathan Sieff and Lee Davy-Martin. Between 2016 and 2017, it was based at the Imperial White City Incubator, and since 2017 has been headquartered at the nearby Translation & Innovation Hub (I-HUB). In January 2018, Niall Dunne became CEO, and in March 2018 the company brought its first product to market.
Prince Charles visited the Polymateria laboratories in March 2019.
In October 2019, Polymateria announced a partnership with specialty chemical company Clariant to bring its new Biotransformation technology to the Southeast Asian market.
A subsequent partnership agreement between Polymateria, Clariant and the Indian Ministry of Chemicals and Fertilizers announced in January 2020 aims to bring Biotransformation to India.
In July 2020, the impact investing platform Planet First Partners (PFP) invested £15 million in Polymateria. Alongside the investment, several people joined the Polymateria board, including PFP head Frédéric de Mévius and former Marks & Spencer CEO Marc Bolland as chairman. The same month, it was reported that Puma would be the first company to use Polymateria's technology in the 160 million plastic bags it used each year, starting September 2020 in Southeast Asian markets, and in Britain in 2021.
The family of Hong Kong billionaire Silas Chou, whose daughter Veronica Chou was said to be pushing for more sustainability in the fashion industry, invested in Polymateria in 2020.
Two years after Polymateria CEO Niall Dunne announced his company's intention to become the "Tesla of plastics",
in November 2020, former Tesla executive Steven Altmann-Richer joined Polymateria as head of public affairs and regulatory strategy. Also in November 2020, the company hinted that its product was already being tested in commercial food packaging in the UK, Spain, Portugal, Taiwan and Kenya, although it did not reveal which brands or products were involved.
In February 2021, clothing company Pour les Femmes announced that it would be using Polymateria's biodegradable plastic in its packaging. Electric racing series Extreme E revealed in March 2021 its partnership with Polymateria, which will supply cups and food packaging for the event, and later collect these for recycling.
In April 2021, FiberVisions and Avgol, two companies owned by Thai Indorama Ventures, partnered with Polymateria, planning to apply the technology to their nonwoven fabrics, which are used for products like face masks and diapers.
The company signed a deal in September 2021 with Taiwanese Formosa Plastics Corp, potentially worth US$100 million in license fees. By then, Polymateria's plastics were also used in some of the packaging of Taiwanese 7-Eleven stores.
The technology was demonstrated during the 2022 Chicago Marathon, on sugarcane-based recovery bags for the runners.
Since 2023, their technology has been branded as "Lyfecycle", and in that same year was applied to plastic bags from Indian fashion brand Doodlage.
In April 2023, Polymateria partnered with Toppan Specialty Films, an Indian plastic manufacturer based in the Punjab region. In May 2023, the company received another £20 million investment, while also signing a deal with a subsidiary of Lotte Chemical to develop products in Malaysia. After the £20 million investment, CEO Dunne announced expansion plans for the company, and also hinted that turnover was in the lower millions, and that the company had experienced growth of 300% between 2021 and 2022.
By January 2024 the company had introduced a biodegradeable baler twine which was produced by a Portuguese firm.
Biodegradable plastics
Biotransformation technology
The company has developed a technology called Biotransformation, which involves adding a masterbatch to plastics during production to aid their decomposition.
The technology is applicable to polyolefins, which include the most commonly littered types of plastics: polyethylene (e.g. plastic bags, packaging) and polypropylene (e.g. plastic cups, bottle caps).
Although these plastics can still be recycled, they will also decompose into a waxy substance in less than a year, provided they are exposed to environmental conditions such as sunlight, air and water. Ecotoxicity tests have shown that this intermediary wax is "non-harmful for contact with soil, plants and the aquatic environment". Bacteria and fungi will then digest the wax and break it down into carbon dioxide and water. It does not leave behind microplastics, a common problem of previous biodegradable products. According to Polymateria, this is achieved because the additives do not just break down the amorphous, but also the crystalline regions of the polymer. The resulting substance thus has a molecular weight of only around 6001000 daltons, compared to existing technologies which were unable to get below 5000 daltons. At these lower levels, the polymer is broken down enough to become a waxy substance biologically available to microbes.
Under sub-optimal conditions, degradation might take slightly longer, with an experimental flowerpot taking up to two years to dissolve if "tossed in a ditch".
The company claims that the onset of biodegradation can be precisely time-controlled, so plastics won't deteriorate before recycling can happen. CEO Dunne said it was looking to apply "terms consumers understand" to the new packaging, such as "recycle-by dates or where recycling isn’t an option dispose-by dates".
Production of the additive in form of a masterbatch was done at a factory in Clermont-Ferrand in 2020, but the company was in talks for a larger facility in India. The technology is expected to increase the cost of packaging by 10 to 15 percent.
A study of Polymateria's plastic biodegradation performance was published in Polymers in July 2021.
BSI standard
In 2020, a new British standard for biodegradability named PAS 9017 was adopted by the BSI Group. Polymateria had sponsored the standard, which was reviewed by the Waste & Resources Action Programme (WRAP), the Department for Environment, Food and Rural Affairs and the Department for Business, Energy and Industrial Strategy. Polymateria's product became the first to reach the new benchmark. Ecologist Dannielle Green of Anglia Ruskin University, who was involved in validating the standard, called it a "step in the right direction" and praised the "interdisciplinary collaborative approach" taken by the BSI.
Criticism and rebuttal
The BSI standard was criticised on 22 October 2020 in an open letter by a group of 40 organizations, including Tesco, Aldi and the Environmental Services Association. The letter called upon the UK government to "follow the lead" of the European Union in banning oxo-degradable plastics, warning of the dangers of "microplastics [...] entering the food chain" and claiming that "degradable plastic alternatives will disrupt [Britain]'s recycling facilities". WRAP, a registered charity that was on the steering committee for the standard, responded to inquiries by declaring that its involvement should not be mistaken as an endorsement of the standard. However, WRAP maintained that littering was a "real issue" and that it would continue to encourage "developments in plastics technologies which have no negative impact on the ability for plastic to be effectively recycled and have no negative impacts to the natural environment". After a "small but significant anomaly" was found in the BSI consultation process, WRAP said in December 2020 that the committee was due to meet in January the next year to discuss details of the testing process for microplastics.
However, Polymateria's Biotransformation technology does not involve the oxo-degradable plastics criticised by the open letter, which are often confused with biodegradable plastics. It also does not produce microplastics (as required by the PAS 9017 standard), and the company insists its chemical additive has "no adverse impact on recycling streams".
Environmental organizations that have criticized the BSI standard have included the WWF and Keep Britain Tidy, which voiced concerns that degradable plastics would increase littering.
Polymateria CEO Dunne countered by declaring that the main problem were exports to non-EU countries where the plastic waste was "not being recycled and is winding up in unmanaged waste systems." The BSI has responded by calling littering "illegal" and a "complex behavioural issue", voicing doubts that any standard would be able to "control how a member of the public acts". The "recycle-by" date stamped on Polymateria's plastics is also meant to encourage consumers to recycle the product, instead of throwing it away.
See also
Biodegradable polymer
Circular economy
Notes
References
External links
Video interview with Polymateria CEO Niall Dunne by Dr. Miniya Chatterji
2015 establishments in England
Privately held companies based in London
Biodegradable waste management | Polymateria | Chemistry | 1,910 |
44,465,987 | https://en.wikipedia.org/wiki/Non-constructive%20algorithm%20existence%20proofs | The vast majority of positive results about computational problems are constructive proofs, i.e., a computational problem is proved to be solvable by showing an algorithm that solves it; a computational problem is shown to be in P by showing an algorithm that solves it in time that is polynomial in the size of the input; etc.
However, there are several non-constructive results, where an algorithm is proved to exist without showing the algorithm itself. Several techniques are used to provide such existence proofs.
Using an unknown finite set
In combinatorial game theory
A simple example of a non-constructive algorithm was published in 1982 by Elwyn R. Berlekamp, John H. Conway, and Richard K. Guy, in their book Winning Ways for Your Mathematical Plays. It concerns the game of Sylver Coinage, in which players take turns specifying a positive integer that cannot be expressed as a sum of previously specified values, with a player losing when they are forced to specify the number 1. There exists an algorithm (given in the book as a flow chart) for determining whether a given first move is winning or losing: if it is a prime number greater than three, or one of a finite set of 3-smooth numbers, then it is a winning first move, and otherwise it is losing. However, the finite set is not known.
In graph theory
Non-constructive algorithm proofs for problems in graph theory were studied beginning in 1988 by Michael Fellows and Michael Langston.
A common question in graph theory is whether a certain input graph has a certain property. For example:
Input: a graph G.
Question: Can G be embedded in a 3-dimensional space, such that no two disjoint cycles of G are topologically linked (as in links of a chain)?
There is a highly exponential algorithm that decides whether two cycles embedded in a 3d-space are linked, and one could test all pairs of cycles in the graph, but it is not obvious how to account for all possible embeddings in a 3d-space. Thus, it is a-priori not clear at all if the linkedness problem is decidable.
However, there is a non-constructive proof that shows that linkedness is decidable in polynomial time. The proof relies on the following facts:
The set of graphs for which the answer is "yes" is closed under taking minors. I. e., if a graph G can be embedded linklessly in 3-d space, then every minor of G can also be embedded linklessly.
For every two graphs G and H, it is possible to find in polynomial time whether H is a minor of G.
By Robertson–Seymour theorem, any set of finite graphs contains only a finite number of minor-minimal elements. In particular, the set of "yes" instances has a finite number of minor-minimal elements.
Given an input graph G, the following "algorithm" solves the above problem:
For every minor-minimal element H:
If H is a minor of G then return "yes".
return "no".
The non-constructive part here is the Robertson–Seymour theorem. Although it guarantees that there is a finite number of minor-minimal elements it does not tell us what these elements are. Therefore, we cannot really execute the "algorithm" mentioned above. But, we do know that an algorithm exists and that its runtime is polynomial.
There are many more similar problems whose decidability can be proved in a similar way. In some cases, the knowledge that a problem can be proved in a polynomial time has led researchers to search and find an actual polynomial-time algorithm that solves the problem in an entirely different way. This shows that non-constructive proofs can have constructive outcomes.
The main idea is that a problem can be solved using an algorithm that uses, as a parameter, an unknown set. Although the set is unknown, we know that it must be finite, and thus a polynomial-time algorithm exists.
There are many other combinatorial problems that can be solved with a similar technique.
Counting the algorithms
Sometimes the number of potential algorithms for a given problem is finite. We can count the number of possible algorithms and prove that only a bounded number of them are "bad", so at least one algorithm must be "good".
As an example, consider the following problem.
I select a vector v composed of n elements which are integers between 0 and a certain constant d.
You have to guess v by asking sum queries, which are queries of the form: "what is the sum of the elements with indices i and j?". A sum query can relate to any number of indices from 1 to n.
How many queries do you need? Obviously, n queries are always sufficient, because you can use n queries asking for the "sum" of a single element. But when d is sufficiently small, it is possible to do better. The general idea is as follows.
Every query can be represented as a 1-by-n vector whose elements are all in the set {0,1}. The response to the query is just the dot product of the query vector by v. Every set of k queries can be represented by a k-by-n matrix over {0,1}; the set of responses is the product of the matrix by v.
A matrix M is "good" if it enables us to uniquely identify v. This means that, for every vector v, the product M v is unique. A matrix M is "bad" if there are two different vectors, v and u, such that M v = M u.
Using some algebra, it is possible to bound the number of "bad" matrices. The bound is a function of d and k. Thus, for a sufficiently small d, there must be a "good" matrix with a small k, which corresponds to an efficient algorithm for solving the identification problem.
This proof is non-constructive in two ways: it is not known how to find a good matrix; and even if a good matrix is supplied, it is not known how to efficiently re-construct the vector from the query replies.
There are many more similar problems which can be proved to be solvable in a similar way.
Additional examples
Some computational problems can be shown to be decidable by using the Law of Excluded Middle. Such proofs are usually not very useful in practice, since the problems involved are quite artificial.
An example from Quantum complexity theory (related to Quantum query complexity) is given in.
References
Credits
The references in this page were collected from the following Stack Exchange threads:
See also
Existence theorem#'Pure' existence results
Constructive proof#Non-constructive proofs
Computational complexity theory
Constructivism (mathematics) | Non-constructive algorithm existence proofs | Mathematics | 1,378 |
51,583,637 | https://en.wikipedia.org/wiki/Amanita%20basii | Amanita basii is a mushroom of the family Amanitaceae.
Description
Its cap is at around wide, with a brown reddish color to "cadmium orange" becoming very intense red, "lake red" or brownish red in the center part of the cap, which is somewhat faded by the sun, in spots it's red-orange, orange-yellow to deep orange at the margin, yellow at the margin in maturity. The volva seen in the mushroom is absent in maturity or is present when young as small white patches. Its flesh has a color ranging from butter yellow to yellowish under the cap skin, yellow in the center part and near the margin, from pale yellowish white to white elsewhere, the flesh is around thick above the stem, and it thins evenly to the margin. The gills are free, subcrowded, thickest close to the margin, and are around 9–12 mm broad.
The stem is 124–137 × 16–23 mm with a pale yellowish to orange color in the upper part of the stem with light yellow as the ground color. The ring is attached in the upper part, subapical, skirt-like, copious, membranous, persistent, orange-yellow at first, becoming yellow-orange. The saccate volva is smooth, white, with yellow tints on the inner surface, dry, membranous, firmly attached to the stem. The flesh is white, staining light yellow, and stuffed with moderately dense material.
Its stem is around 12.4–13.7 cm × 1.6–2.3 cm, with a pale yellow to orange color in the upper part of the mushroom's stem with a light yellow on the ground, becoming brown to blackish with handling, stuffed, subcylindric to cylindrical, with irregular ragged patches and strands of orange-yellow felted to membranous material on the outer surface; the stem decoration becomes more intensely orange when handled. The ring is attached in the upper part, subapical, skirt-like, copious, membranous, persistent, orange-yellow at first, becoming yellow-orange. The saccate volva is smooth, white, with yellowish tints on the inner surface, dry, membranous, firmly attached to the stem. The flesh is white, staining light yellow, and stuffed with moderately dense material.
The spores measure around approximately 9.0–11.8 (8.0–18.0) × 6.1–7.5(5.5–9.0) μm and are broadly ellipsoid to elongate (rarely cylindric) and inamyloid. Clamps are common at bases of basidia.
Similar species
Not to be confused with Amanita laurae, which grows under oaks, A. yema (under firs) and A. jacksonii, which grows in cloud forest.
Distribution and habitat
It occurs in pine forests in Mexico.
Uses
Though not as well known as other edible mushroom species, A. basii is considered to be edible and has a sweet taste. The odor is somewhat pleasantly fungoid.
See also
Amanita
List of Amanita Species
References
basii
Edible fungi
Taxa named by Gastón Guzmán
Fungus species | Amanita basii | Biology | 673 |
3,326,836 | https://en.wikipedia.org/wiki/CALIPSO | CALIPSO was a joint NASA (US) and CNES (France) environmental satellite, built in the Cannes Mandelieu Space Center, which was launched atop a Delta II rocket on April 28, 2006. Its name stands for Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. CALIPSO launched alongside CloudSat.
Passive and active remote sensing instruments on board the CALIPSO satellite monitored aerosols and clouds 24 hours a day. CALIPSO was part of the "C-Train" alongside CloudSat, orbiting on a similar track to the "A-Train." The mission ended on August 1, 2023 after over 17 years. Final passivation occurred on December 11, 2023.
Mission
Three instruments:
Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) - a lidar that provided high-resolution vertical profiles of aerosols and clouds.
Wide Field Camera (WFC) - a modified version of the commercial off-the-shelf Ball Aerospace CT-633 star tracker camera. It was selected to match band 1 of the MODIS instrument on the Aqua satellite.
Imaging Infrared Radiometer (IIR) - used to detect cirrus cloud emissivity and particle size. The CALIOP laser beam is aligned with the center of the IIR image to optimize joint CALIOP/IIR observations.
In February 2009, CALIPSO switched over to the redundant laser as scheduled. The primary laser achieved its mission goal of three years of successful operation, and the redundant laser has been performing beyond expectations.
The CALIPSO mission was granted extended mission status in June 2009. CALIPSO moved to the C-Train in 2020. The mission ended on August 1, 2023 due to lack of propellant.
See also
A-train (satellite constellation)
Earth Observing System
List of spaceflights (2006)
References
External links
CALIPSO Outreach
CALIPSO and the A Train
The CALIPSO page at NASA
The CALIPSO page at French National Centre for Space Studies (CNES)
CALIPSO Mission Profile by NASA's Solar System Exploration
CALIPSO results in five to ten years
CALIPSO specs at NASA
(https://www.nasa.gov/feature/first-long-duration-lidar-satellite-mission-calipso-ends)
Earth observation satellites of the United States
Environmental science
Satellites orbiting Earth
Satellite meteorology
Satellites of France
Spacecraft launched by Delta II rockets
Spacecraft launched in 2006
NASA satellites
2006 in France
Spacecraft decommissioned in 2023 | CALIPSO | Environmental_science | 520 |
47,289,026 | https://en.wikipedia.org/wiki/Testosterone%20acetate | Testosterone acetate (brand names Aceto-Sterandryl, Aceto-Testoviron, Amolisin, Androtest A, Deposteron, Farmatest, Perandrone A), or testosterone ethanoate, also known as androst-4-en-17β-ol-3-one 17β-acetate, is an androgen and anabolic steroid and a testosterone ester. The drug was first described in 1936 and was one of the first androgen esters and esters of testosterone to be synthesized.
See also
List of androgen esters
References
Acetate esters
Anabolic–androgenic steroids
Androstanes
Ketones
Testosterone esters | Testosterone acetate | Chemistry | 148 |
1,503,460 | https://en.wikipedia.org/wiki/McNeill%27s%20law | In human geography, McNeill's law is the process outlined in William H. McNeill's book Plagues and Peoples. The process described concerns the role of microbial disease in the conquering of people-groups. Particularly, it describes how diseases such as smallpox, measles, typhus, scarlet fever, and sexually-transmitted diseases have significantly reduced native populations so that they are unable to resist colonization.
Concept
According to McNeill's Law, the microbiological aspect of conquest and invasion has been the deciding principle or one of the deciding principles in both the expansion of certain empires (as during the emigration to the Americas) and the containment in others (as during the crusades). The argument is that less civilized peoples were easily subjugated due to the immunological advantages of those coming from civilized countries. An evidence presented to support the hypothesis involves the manner diseases associated with Europeans were rebuffed in their forays into disease-experienced countries such as China and Japan.
McNeill's law also maintains that parasites are not only natural but also social in the sense that these organisms are part of the social continuum and that the human social evolution is inextricably linked with genetic transformations.
Instances in history
The first people-group fully wiped out due to European expansion (with the possible exception of the Arawaks) was the Guanches of the Canary Islands. Despite an inbred ferocity, superior knowledge of the land and even a possible tactical superiority, they were eventually wiped out through the concentrated efforts of the Spanish and Portuguese. McNeill's Law would place the deciding factor squarely on the introduction of deadly diseases and parasites from the mainland to the previously geographically isolated islanders.
This is the likely explanation, as what records still exist show numerous deaths by disease on the islands and a declining birth rate, leading eventually to the almost complete end of the Guanches as a race.
Other instances include the devastation of the Incas by smallpox.
References
Human geography
Epidemiology | McNeill's law | Environmental_science | 414 |
13,482,790 | https://en.wikipedia.org/wiki/List%20of%20psilocybin%20mushroom%20species | Psilocybin mushrooms are mushrooms which contain the hallucinogenic substances psilocybin, psilocin, baeocystin and norbaeocystin. The mushrooms are collected and grown as an entheogen and recreational drug, despite being illegal in many countries. Many psilocybin mushrooms are in the genus Psilocybe, but species across several other genera contain the drugs.
General
Conocybula
Galerina
Gymnopilus
Inocybe
Panaeolus
Pluteus
Psilocybe
Conocybula
Conocybe siligineoides R. Heim
Conocybula cyanopus (G.F. Atk.) T. Bau & H. B. Song
Conocybula smithii (Watling) T. Bau & H. B. Song (Galera cyanopes Kauffman, Conocybe smithii Watling)
Galerina
Galerina steglichii Besl
Gymnopilus
Gymnopilus aeruginosus (Peck) Singer (photo)
Gymnopilus braendlei (Peck) Hesler
Gymnopilus cyanopalmicola Guzm.-Dáv
Gymnopilus dilepis (Berk. & Broome) Singer
Gymnopilus dunensis H. Bashir, Jabeen & Khalid
Gymnopilus intermedius (Singer) Singer
Gymnopilus lateritius (Pat.) Murrill
Gymnopilus luteofolius (Peck) Singer (photo)
Gymnopilus luteoviridis Thiers (photo)
Gymnopilus luteus (Peck) Hesler (photo)
Gymnopilus palmicola Murrill
Gymnopilus purpuratus (Cooke & Massee) Singer (photo)
Gymnopilus subpurpuratus Guzmán-Davalos & Guzmán
Gymnopilus subspectabilis Hesler
Gymnopilus validipes (Peck) Hesler
Gymnopilus viridans Murrill
Inocybe
Inocybe aeruginascens Babos
Inocybe caerulata Matheny, Bougher & G.M. Gates
Inocybe coelestium Kuyper
Inocybe corydalina
Inocybe corydalina var. corydalina Quél.
Inocybe corydalina var. erinaceomorpha (Stangl & J. Veselsky) Kuyper
Inocybe haemacta (Berk. & Cooke) Sacc.
Inocybe tricolor Kühner
Most species in this genus are poisonous.
Panaeolus
Panaeolus affinis (E. Horak) Ew. Gerhardt
Panaeolus africanus Ola'h
Panaeolus axfordii Y. Hu, S.C. Karunarathna, P.E. Mortimer & J.C. Xu
Panaeolus bisporus (Malencon and Bertault) Singer and Weeks
Panaeolus cambodginiensis (OlaĽh et Heim) Singer & Weeks. (Merlin & Allen, 1993)
Panaeolus chlorocystis (Singer & R.A. Weeks) Ew. Gerhardt
Panaeolus cinctulus (Bolton) Britzelm.
Panaeolus cyanescens (Berk. & Broome) Sacc.
Panaeolus fimicola (Fr.) Gillet
Panaeolus lentisporus Ew. Gerhardt
Panaeolus microsporus Ola'h & Cailleux
Panaeolus moellerianus Singer
Panaeolus olivaceus F.H. Møller
Panaeolus rubricaulis Petch (= Panaeolus campanuloides Guzmán & K. Yokoy.)
Panaeolus tirunelveliensis (Natarajan & Raman) Ew. Gerhardt
Panaeolus tropicalis Ola'h
Panaeolus venezolanus Guzmán (= Panaeolus annulatus Natarajan & Raman)
Pluteus
Pluteus albostipitatus (Dennis) Singer
Pluteus americanus (P. Banerjee & Sundb.) Justo, E.F. Malysheva & Minnis (2014)
Pluteus brunneidiscus Murrill (1917).
Pluteus cyanopus Quél.
Pluteus glaucus Singer
Pluteus glaucotinctus E. Horak
Pluteus nigroviridis Babos
Pluteus phaeocyanopus Minnis & Sundb.
Pluteus salicinus (Pers. : Fr.) P. Kumm.
Pluteus saupei Justo & Minnis
Pluteus velutinornatus G. Stev. 1962.
Pluteus villosus (Bull.) Quél.
Psilocybe
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A
Psilocybe acutipilea (Speg.) Guzmán
Psilocybe allenii Borov., Rockefeller & P.G.Werner
Psilocybe alutacea Y.S. Chang & A.K. Mills
Psilocybe angulospora Yen W. Wang & S.S. Tzean
Psilocybe antioquiensis Guzmán, Saldarriaga, Pineda, García & Velázquez
Psilocybe araucariicola P. S. Silva & Ram.-Cruz
Psilocybe atlantis Guzmán, Hanlin & C. White
Psilocybe aquamarina (Pegler) Guzmán
Psilocybe armandii Guzmán & S.H. Pollock
Psilocybe aucklandiae Guzmán, C.C. King & Bandala
Psilocybe aztecorum
Psilocybe aztecorum var. aztecorum
Psilocybe aztecorum var. bonetii (Guzmán) Guzmán
Psilocybe azurescens Stamets & Gartz
B
Psilocybe baeocystis Singer & A.H. Sm. emend. Guzmán
Psilocybe banderillensis Guzmán
Psilocybe brasiliensis Guzmán
Psilocybe brunneocystidiata Guzmán & Horak
C
Psilocybe caeruleoannulata Singer ex Guzmán
Psilocybe caerulescens
Psilocybe caerulescens var. caerulescens Murrill
Psilocybe caerulescens var. ombrophila (R. Heim) Guzmán
Psilocybe caerulipes (Peck) Sacc.
Psilocybe callosa
Psilocybe carbonaria Singer
Psilocybe chuxiongensis T.Ma & K.D.Hyde
Psilocybe collybioides Singer & A.H. Sm.
Psilocybe columbiana Guzmán
Psilocybe congolensis Guzmán, S.C. Nixon & Cortés-Pérez
Psilocybe cordispora R. Heim
Psilocybe cubensis (Earle) Singer
Psilocybe cyanescens Wakef. (non-sensu Krieglsteiner)
Psilocybe cyanofibrillosa Guzmán & Stamets
D
Psilocybe dumontii Singer ex Guzmán
E
Psilocybe egonii Guzmán & T.J. Baroni
Psilocybe eximia E. Horak & Desjardin
F
Psilocybe fagicola
Psilocybe fagicola var. fagicola
Psilocybe fagicola var. mesocystidiata Guzmán
Psilocybe farinacea Rick ex Guzmán
Psilocybe fimetaria (P.D. Orton) Watling
Psilocybe fuliginosa (Murrill) A.H. Sm.
Psilocybe furtadoana Guzmán
G
Psilocybe galindoi Guzmán
Psilocybe gallaeciae Guzmán & M.L. Castro
Psilocybe graveolens Peck
Psilocybe guatapensis Guzmán, Saldarriaga, Pineda, García & Velázquez
Psilocybe guilartensis Guzmán, Tapia & Nieves-Rivera
H
Psilocybe heimii Guzmán
Psilocybe herrerae Guzmán
Psilocybe hispanica Guzmán
Psilocybe hoogshagenii
Psilocybe hoogshagenii var. hoogshagenii "(= Psilocybe caerulipes var. gastonii Singer, Psilocybe zapotecorum R. Heim s. Singer)"
Psilocybe hoogshagenii var. convexa Guzmán (= Psilocybe semperviva R. Heim & Cailleux)
Psilocybe hopii Guzmán & J. Greene
I
Psilocybe inconspicua Guzmán & Horak
Psilocybe indica Sathe & J.T. Daniel
Psilocybe ingeli B. van der Merwe, A. Rockefeller & K Jacobs
Psilocybe isabelae Guzmán
J
Psilocybe jacobsii Guzmán
Psilocybe jaliscana Guzmán
K
Psilocybe kumaenorum R. Heim
L
Psilocybe laurae Guzmán
Psilocybe lazoi Singer
Psilocybe liniformans
Psilocybe liniformans var. liniformans
Psilocybe liniformans var. americana Guzmán & Stamets
M
Psilocybe mairei Singer
Psilocybe makarorae Johnst. & Buchanan
Psilocybe maluti B. van der Merwe, A. Rockefeller & K. Jacobs
Psilocybe mammillata (Murrill) A.H. Sm.
Psilocybe medullosa (Bres.) Borovička
Psilocybe meridensis Guzmán
Psilocybe meridionalis Guzmán, Ram.-Guill. & Guzm.-Dáv.
Psilocybe mescaleroensis Guzmán, Walstad, E. Gándara & Ram.-Guill.
Psilocybe mexicana R. Heim
Psilocybe moseri Guzmán
Psilocybe muliercula Singer & A.H. Sm. (= Psilocybe wassonii R. Heim)
N
Psilocybe naematoliformis Guzmán
Psilocybe natalensis Gartz, Reid, Smith & Eicker
Psilocybe natarajanii Guzmán (= Psilocybe aztecorum var. bonetii (Guzmán) Guzmán s. Natarajan & Raman)
Psilocybe neorhombispora Guzmán & Horak
Psilocybe neoxalapensis Guzmán, Ram.-Guill. & Halling
Psilocybe ningshanensis X.L. He, W.Y. Huo, L.G. Zhang, Y. Liu & J.Z. Li
Psilocybe niveotropicalis Ostuni, Rockefeller, J. Jacobs & Birkebak
O
Psilocybe ovoideocystidiata Guzmán et Gaines
P
Psilocybe papuana Guzmán & Horak
Psilocybe paulensis (Guzmán & Bononi) Guzmán (= Psilocybe banderiliensis var. paulensis Guzmán & Bononi)
Psilocybe pelliculosa (A.H. Sm.) Singer & A.H. Sm.
Psilocybe pintonii Guzmán
Psilocybe pleurocystidiosa Guzmán
Psilocybe plutonia (Berk. & M.A. Curtis) Sacc.
Psilocybe portoricensis Guzmán, Tapia & Nieves-Rivera
Psilocybe pseudoaztecorum Natarajan & Raman
Psilocybe puberula Bas & Noordel.
Q
Psilocybe quebecensis Ola'h & R. Heim
R
Psilocybe rickii Guzmán & Cortez
Psilocybe rostrata (Petch) Pegler
Psilocybe rzedowskii Guzmán
S
Psilocybe samuiensis Guzmán, Bandala & Allen
Psilocybe schultesii Guzmán & S.H. Pollock
Psilocybe semilanceata (Fr. : Secr.) P. Kumm.
Psilocybe septentrionalis (Guzmán) Guzmán (= Psilocybe subaeriginascens Höhn. var. septentrionalis Guzmán)
Psilocybe serbica Moser & Horak (non ss. Krieglsteiner)
Psilocybe sierrae Singer (= Psilocybe subfimetaria Guzmán & A.H. Sm.)
Psilocybe silvatica (Peck) Singer & A.H. Sm.
Psilocybe singeri Guzmán
Psilocybe strictipes Singer & A.H. Sm.
Psilocybe stuntzii Guzman & Ott
Psilocybe subacutipilea Guzmán, Saldarriaga, Pineda, García & Velázquez
Psilocybe subaeruginascens Hohnel
Psilocybe subaeruginosa Cleland
Psilocybe subbrunneocystidiata P.S. Silva & Guzmán
Psilocybe subcaerulipes Hongo
Psilocybe subcubensis Guzmán
Psilocybe subpsilocybioides Guzmán, Lodge & S.A. Cantrell
Psilocybe subtropicalis Guzmán
T
Psilocybe tampanensis Guzmán & S.H. Pollock (photo)
Psilocybe tasmaniana Guzmán & Watling (1978)
Psilocybe thaiaerugineomaculans Guzmán, Karunarathna & Ram.-Guill.
Psilocybe thaicordispora Guzmán, Ram.-Guill. & Karun.
Psilocybe thaiduplicatocystidiata Guzmán, Karun. & Ram.-Guill.
U
Psilocybe uruguayensis Singer ex Guzmán
Psilocybe uxpanapensis Guzmán
V
Psilocybe venenata (S. Imai) Imaz. & Hongo (= Psilocybe fasciata Hongo; Stropharia caerulescens S. Imai)
W
Psilocybe wassoniorum Guzmán & S.H. Pollock
Psilocybe wayanadensis K.A. Thomas, Manim. & Guzmán
Psilocybe weilii Guzmán, Tapia & Stamets (photo)
Psilocybe weldenii Guzmán
Psilocybe weraroa Borovicka, Oborník & Noordel.
X
Psilocybe xalapensis Guzmán & A. López
Y
Psilocybe yungensis Singer & A.H. Sm.
Z
Psilocybe zapotecoantillarum Guzmán, T.J. Baroni & Lodge
Psilocybe zapotecocaribaea Guzmán, Ram.-Guill. & T.J. Baroni
Psilocybe zapotecorum
References
Entheogens
Psilocybin species
Psychoactive fungi
Psychedelic tryptamine carriers
Hallucinations | List of psilocybin mushroom species | Biology | 3,204 |
2,257,041 | https://en.wikipedia.org/wiki/Multireference%20configuration%20interaction | In quantum chemistry, the multireference configuration interaction (MRCI) method consists of a configuration interaction expansion of the eigenstates of the electronic molecular Hamiltonian in a set of Slater determinants which correspond to excitations of the ground state electronic configuration but also of some excited states. The Slater determinants from which the excitations are performed are called reference determinants. The higher excited determinants (also called configuration state functions (CSFs) or shortly configurations) are then chosen either by the program according to some perturbation theoretical ansatz according to a threshold provided by the user or simply by truncating excitations from these references to singly, doubly, ... excitations resulting in MRCIS, MRCISD, etc.
For the ground state using more than one reference configuration means a better correlation and so a lower energy. The problem of size inconsistency of truncated CI-methods is not solved by taking more references.
As a result of a MRCI calculation one gets a more balanced correlation of the ground and excited states. For quantitative good energy differences (excitation energies) one has to be careful in selecting the references. Taking only the dominant configuration of an excited state into the reference space leads to a correlated (lower) energy of the excited state. The generally too-high excitation energies of CIS or CISD are lowered. But usually excited states have more than one dominant configuration and so the ground state is more correlated due to: a) now including some configurations with higher excitations (triply and quadruply in MRCISD); b) the neglect of other dominant configurations of the excited states which are still uncorrelated.
Selecting the references can be done manually (), automatically (all possible configurations within an active space of some orbitals) or semiautomatically (taking all configurations as references that have been shown to be important in a previous CI or MRCI calculation)
This method has been implemented first by Robert Buenker and Sigrid D. Peyerimhoff in the seventies under the name Multi-Reference Single and Double Configuration Interaction (MRSDCI). MRCI was further streamlined in 1988 by Hans-Joachim Werner and Peter Knowles, which made previous MRCI procedures more generalizable.
The MRCI method can also be implemented in semi-empirical methods. An example for this is the OM2/MRCI method developed by Walter Thiel's group.
See also
Configuration interaction
References
Quantum chemistry | Multireference configuration interaction | Physics,Chemistry | 517 |
2,615,949 | https://en.wikipedia.org/wiki/Omega%20network | An Omega network is a network configuration often used in parallel computing architectures. It is an indirect topology that relies on the perfect shuffle interconnection algorithm.
Connection architecture
An 8x8 Omega network is a multistage interconnection network, meaning that processing elements (PEs) are connected using multiple stages of switches. Inputs and outputs are given addresses as shown in the figure. The outputs from each stage are connected to the inputs of the next stage using a perfect shuffle connection system. This means that the connections at each stage represent the movement of a deck of cards divided into 2 equal decks and then shuffled together, with each card from one deck alternating with the corresponding card from the other deck. In terms of binary representation of the PEs, each stage of the perfect shuffle can be thought of as a cyclic logical left shift; each bit in the address is shifted once to the left, with the most significant bit moving to the least significant bit.
At each stage, adjacent pairs of inputs are connected to a simple exchange element, which can be set either straight (pass inputs directly through to outputs) or crossed (send top input to bottom output, and vice versa). For N processing element, an Omega network contains N/2 switches at each stage, and log2N stages. The manner in which these switches are set determines the connection paths available in the network at any given time. Two such methods are destination-tag routing and XOR-tag routing, discussed in detail below.
The Omega Network is highly blocking, though one path can always be made from any input to any output in a free network.
Destination-tag routing
In destination-tag routing, switch settings are determined solely by the message destination. The most significant bit of the destination address is used to select the output of the switch in the first stage; if the most significant bit is 0, the upper output is selected, and if it is 1, the lower output is selected. The next-most significant bit of the destination address is used to select the output of the switch in the next stage, and so on until the final output has been selected.
For example, if a message's destination is PE 001, the switch settings are: upper, upper, lower. If a message's destination is PE 101, the switch settings are: lower, upper, lower. These switch settings hold regardless of the PE sending the message.
XOR-tag routing
In XOR-tag routing, switch settings are based on (source PE) XOR (destination PE). This XOR-tag contains 1s in the bit positions that must be swapped and 0s in the bit positions that both source and destination have in common. The most significant bit of the XOR-tag is used to select the setting of the switch in the first stage; if the most significant bit is 0, the switch is set to pass-through, and if it is 1, the switch is crossed. The next-most significant bit of the tag is used to set the switch in the next stage, and so on until the final output has been selected.
For example, if PE 001 wishes to send a message to PE 010, the XOR-tag will be 011 and the appropriate switch settings are: A2 straight, B3 crossed, C2 crossed.
Applications
In multiprocessing, omega networks may be used as connectors between the CPUs and their shared memory, in order to decrease the probability that the CPU-to-memory connection becomes a bottleneck.
This class of networks has been built into the Illinois Cedar Multiprocessor, into the IBM RP3, and into the NYU Ultracomputer.
Examples
Omega network simulation in c
See also
Clos network
Cube-connected cycles
Nonblocking minimal spanning switch
Banyan switch
Delta network
Fat tree
Crossbar switch
Network coding
References
Network architecture | Omega network | Engineering | 785 |
78,923,697 | https://en.wikipedia.org/wiki/PKS%201335%E2%88%92127 | PKS 1335-127 is a blazar located in the constellation of Virgo with a redshift of (z) 0.539. This is a compact BL Lac object containing a radio source of extragalactic origins; discovered in 1970 during the continuum survey conducted by astronomers from Ohio State University. The object shows a radio spectrum appearing as flat, thus making it a flat-spectrum radio quasar (FRSQ), but also classified as a gigahertz-peaked source (GPS) with high polarization.
Description
PKS 1335-127 is considered to be variable on the electromagnetic spectrum. It is known to produce a near-infrared flare which was detected in February 2013 showing a H-band flux value of 13.691 ± 0.08. Enhanced gamma-ray activity was observed from the object in May 2020, followed by an optical flare one month later. There is presence of large amplitude variability and evidence of position angles showing different rotations at both low and high frequencies from the object.
Radio imaging made by the Very Long Baseline Array on arcsecond scales, shows the structure of PKS 1335-127 is mainly made up of a radio core and a radio jet that is found to curve in an eastwards direction by 6.5" from the core. When imaged at 43 GHz, the jet is revealed to become less defined, with a patch of weak diffused radio emission located southeast. There is also an extended component located at a 152° position angle at a distance of 2.6 milliarcseconds. Earlier observations via a very-long baseline Interferometry (VLBI) map shows the core as unresolved while the jet is found to have an orientation of 135° indicating a perpendicular magnetic field.
Further observations also found the circular polarization in PKS 1335-127 is stable. While images at 15 and 22 GHz respectively shows the presence of compact radio emission focused on the phase center, the image at 43 GHz shows PKS 1335-127 has a double structure containing components with a much stronger southern component. There is also circular polarization towards the jet at its southwestern edge, polarized by 7.16 percent; however it is found 2 factor higher when compared to circular polarization in the jet of 3C 84 (NGC 1275).
References
External links
PKS 1335-127 on SIMBAD
PKS 1335-127 on NASA/IPAC Database
Blazars
Virgo (constellation)
Quasars
BL Lacertae objects
Active galaxies
2827642
Astronomical objects discovered in 1970 | PKS 1335−127 | Astronomy | 531 |
6,800,801 | https://en.wikipedia.org/wiki/Reichert%20value | The Reichert value (also Reichert-Meissl number, Reichert-Meissl-Wollny value or Reichert-Meissl-Wollny number) is a value determined when examining fats and oils. The Reichert value is an indicator of how much volatile fatty acid can be extracted from a particular fat or oil through saponification. It is equal to the number of millilitres of 0.1 normal hydroxide solution necessary for the neutralization of the water-soluble volatile fatty acids distilled and filtered from 5 grams of a given saponified fat. (The hydroxide solution used in such a titration is typically made from sodium hydroxide, potassium hydroxide, or barium hydroxide.)
This number is a useful indicator of non-fat compounds in edible fats, and is especially high in butter.
The value is named for the chemists who developed it, Emil Reichert and Emerich Meissl.
The Polenske value and Kirschner value are related numbers based on similar tests.
The Reichert-Meissel value for milk ranges between 28.5 and 33.
References
External links
Dimensionless numbers of chemistry
Edible oil chemistry | Reichert value | Chemistry | 248 |
4,501,325 | https://en.wikipedia.org/wiki/Plasma%20parameters | Plasma parameters define various characteristics of a plasma, an electrically conductive collection of charged and neutral particles of various species (electrons and ions) that responds collectively to electromagnetic forces. Such particle systems can be studied statistically, i.e., their behaviour can be described based on a limited number of global parameters instead of tracking each particle separately.
Fundamental
The fundamental plasma parameters in a steady state are
the number density of each particle species present in the plasma,
the temperature of each species,
the mass of each species,
the charge of each species,
and the magnetic flux density .
Using these parameters and physical constants, other plasma parameters can be derived.
Other
All quantities are in Gaussian (cgs) units except energy and temperature which are in electronvolts. For the sake of simplicity, a single ionic species is assumed. The ion mass is expressed in units of the proton mass, and the ion charge in units of the elementary charge (in the case of a fully ionized atom, equals to the respective atomic number). The other physical quantities used are the Boltzmann constant speed of light and the Coulomb logarithm
Frequencies
Lengths
Velocities
Dimensionless
number of particles in a Debye sphere
Alfvén speed to speed of light ratio
electron plasma frequency to gyrofrequency ratio
ion plasma frequency to gyrofrequency ratio
thermal pressure to magnetic pressure ratio, or beta, β
magnetic field energy to ion rest energy ratio
Collisionality
In the study of tokamaks, collisionality is a dimensionless parameter which expresses the ratio of the electron-ion collision frequency to the banana orbit frequency.
The plasma collisionality is defined as
where denotes the electron-ion collision frequency, is the major radius of the plasma, is the inverse aspect-ratio, and is the safety factor. The plasma parameters and denote, respectively, the mass and temperature of the ions, and is the Boltzmann constant.
Electron temperature
Temperature is a statistical quantity whose formal definition is
or the change in internal energy with respect to entropy, holding volume and particle number constant. A practical definition comes from the fact that the atoms, molecules, or whatever particles in a system have an average kinetic energy. The average means to average over the kinetic energy of all the particles in a system.
If the velocities of a group of electrons, e.g., in a plasma, follow a Maxwell–Boltzmann distribution, then the electron temperature is defined as the temperature of that distribution. For other distributions, not assumed to be in equilibrium or have a temperature, two-thirds of the average energy is often referred to as the temperature, since for a Maxwell–Boltzmann distribution with three degrees of freedom, .
The SI unit of temperature is the kelvin (K), but using the above relation the electron temperature is often expressed in terms of the energy unit electronvolt (eV). Each kelvin (1 K) corresponds to ; this factor is the ratio of the Boltzmann constant to the elementary charge. Each eV is equivalent to 11,605 kelvins, which can be calculated by the relation .
The electron temperature of a plasma can be several orders of magnitude higher than the temperature of the neutral species or of the ions. This is a result of two facts. Firstly, many plasma sources heat the electrons more strongly than the ions. Secondly, atoms and ions are much heavier than electrons, and energy transfer in a two-body collision is much more efficient if the masses are similar. Therefore, equilibration of the temperature happens very slowly, and is not achieved during the time range of the observation.
See also
Ball-pen probe
Langmuir probe
References
NRL Plasma Formulary – Naval Research Laboratory (2018)
Plasma parameters
Astrophysics | Plasma parameters | Physics,Astronomy | 762 |
1,236,616 | https://en.wikipedia.org/wiki/Hedorah | , also known as the Smog Monster, is a fictional monster, or kaiju who first appeared in Toho's 1971 film Godzilla vs. Hedorah. Hedorah was named for , the Japanese word for sludge, slime, vomit or chemical ooze.
Overview
Development
Whereas Godzilla was a symbol of Japanese concerns over nuclear weapons, Hedorah was envisioned as an embodiment of Yokkaichi asthma, caused by Japan's widespread smog and urban pollution at the time. Director Yoshimitsu Banno stated in an interview that his intention in creating Hedorah was to give Godzilla an adversary who was more than just a "giant lobster" and which represented "the most notorious thing in current society". He also stated that Hedorah's vertically tilted eyes were based on vaginas, which he joked were "scary". The monster was originally going to be named "Hedoron", though this changed once the TV series Spectreman introduced a character with an identical name.
The monster was realized via various props and a large sponge rubber suit donned by future Godzilla performer Kenpachiro Satsuma in his first acting role for Toho. Satsuma had been selected on account of his physical fitness, though he stated later that he had been disappointed to receive the role, as he had grown tired of taking non-speaking roles. In performing as Hedorah, Satsuma tried to emphasize Hedorah's otherworldly nature by making its movements seem more grotesque than animal-like. Several authors have noted that, unlike most Toho monsters, Hedorah's violent acts are graphically shown to claim human victims, and the creature shows genuine amusement at Godzilla's suffering. Banno wished to bring back Hedorah in a sequel set in Africa, but the project never materialized, as he was fired by producer and series co-creator Tomoyuki Tanaka, who allegedly accused him of ruining the Godzilla series. Complex listed the character as #8 on its "The 15 Most Badass Kaiju Monsters of All Time" list.
Banno had hoped to revisit Hedorah in his unrealized project Godzilla 3-D, which would have had featured a similar monster named Deathla. Like its predecessor, Deathla would have been a shape-shifting extraterrestrial, though it would have fed on chlorophyll rather than gas emissions, and all of its forms would have incorporated a skull motif.
Shōwa era (1971)
In Godzilla vs. Hedorah, Hedorah originates from the Dark Gas Nebula in the constellation of Orion. It journeys to Earth via a passing comet, and lands in Suruga Bay as a monstrous tadpole-like creature, increasing in size as it feeds on the pollutants contaminating the water. It proceeds to rampage throughout Japan, killing thousands and feeding on gas emissions and toxic waste, gradually gaining power as it advances from a water stage, to a land stage, and finally a bipedal Perfect Form that it can switch out for a smaller, flying form at any time. Godzilla confronts Hedorah at Mount Fuji, but his atomic breath has no effect on Hedorah's amorphous, water-rich body. Hedorah rapidly overpowers Godzilla using a combination of its fearsome strength and incredible durability, and almost kills the King of the Monsters after hurling him into a pit and attempting to drown him under a deluge of chemical ooze. It is later discovered that Hedorah is vulnerable to temperatures high enough to dehydrate it, so the JSDF constructs a pair of gigantic electrodes on the battlefield to use against the alien. Hedorah and Godzilla continue to fight, and the former is subsequently killed when Godzilla uses his atomic breath to power the electrodes, which cripple Hedorah and allow Godzilla to fully dehydrate its body into dust.
Millennium era (2004)
Hedorah briefly reappears in Godzilla: Final Wars as one of several monsters under the Xiliens' control before it is destroyed by Godzilla alongside Ebirah in Tokyo.
Other
Hedorah also appears in Godzilla: Planet of the Monsterss prequel novel Godzilla: Monster Apocalypse, in which it was originally a colony of sludge-like microorganisms that lived off dissolved chemicals inside a mine in Hebei, China. After the Chinese government discovered it in 1999, they studied and modified the microorganisms to operate as a giant, mist-like bioweapon with red and yellow eyes called Hedorah. In 2005, the Chinese military commenced "Operation: Hedorah" to kill Anguirus and Rodan with the bio-weapon. Hedorah successfully took down the two monsters, but it attained sentience afterwards and went on a rampage, consumed the pollutants in the surrounding area, then disappeared, leaving an estimated 8.2 million casualties in its wake.
A 2021 short film "Godzilla vs. Hedorah" created for the 50th Anniversary of the character would give the Final Wars incarnations of Hedorah and Godzilla a rematch amid an oil refinery in the daytime.
Hedorah also appears in Chibi Godzilla Raids Again.
Appearances
Films
Godzilla vs. Hedorah (1971)
Godzilla: Final Wars (2004)
Godzilla: Planet of the Monsters (2017)
Godzilla vs. Hedorah (2021, short film)
Television
Godzilla Island (1997-1998)
Godziban (2019–present)
Chibi Godzilla Raids Again (2023-2024)
Video games
Godzilla: Monster of Monsters (NES - 1988)
Godzilla / Godzilla-Kun: Kaijuu Daikessen (Game Boy - 1990)
Godzilla 2: War of the Monsters (NES - 1991)
Kaijū-ō Godzilla / King of the Monsters, Godzilla (Game Boy - 1993)
Godzilla: Battle Legends (Turbo Duo - 1993)
Godzilla Trading Battle (PlayStation - 1998)
Godzilla: Destroy All Monsters Melee (GCN, Xbox - 2002/2003)
Godzilla Unleashed: Double Smash (NDS - 2007)
Godzilla: The Game (PS3 - 2014 PS3 PS4 - 2015)
Godzilla Defense Force (2019)
Godzilla Battle Line (2021)
GigaBash (PS4, PS5, Steam, Epic Games - 2024)
Literature
Godzilla vs. Gigan and the Smog Monster (1996)
Godzilla at World’s End (1998)
Godzilla: Monster Apocalypse (2017)
Comics
Godzilla: Legends (comic - 2011–2012)
Godzilla: Ongoing (comic - 2012)
Godzilla: The Half-Century War (comic - 2012–2013)
Godzilla: Rulers of Earth (comic - 2013–2015)
Godzilla Rivals (comic - 2021)
Music
Hedorah appears on the album cover of Frank Zappa's Sleep Dirt.
Hedorah appears on the album cover of Dinosaur Jr's Sweep It Into Space.
References
Bibliography
Extraterrestrial supervillains
Fantasy film characters
Fictional amorphous creatures
Fictional characters with superhuman strength
Fictional mass murderers
Fictional parasite characters
Fictional superorganisms
Film characters introduced in 1971
Godzilla characters
Mothra characters
Horror film villains
Toho monsters | Hedorah | Biology | 1,461 |
6,165,852 | https://en.wikipedia.org/wiki/NRC%20Herzberg%20Astronomy%20and%20Astrophysics%20Research%20Centre | The NRC Herzberg Astronomy and Astrophysics Research Centre (NRC Herzberg, HAA) is the leading Canadian centre for astronomy and astrophysics. It is based in Victoria, British Columbia. The current director-general, as of 2021, is Luc Simard.
History
Named for the Nobel laureate Gerhard Herzberg, it was formed in 1975 as part of the National Research Council of Canada in Ottawa, Ontario. The NRC-HIA headquarters were moved to Victoria, British Columbia in 1995 to the site of the Dominion Astrophysical Observatory. In 2012, the organization was restructured and renamed NRC Herzberg Astronomy and Astrophysics.
Facilities
NRC-HAA also operates the Dominion Radio Astrophysical Observatory outside of Penticton, British Columbia and the Canadian Astronomy Data Centre as well as managing Canadian involvement in the Canada-France-Hawaii Telescope, Gemini Observatory, Atacama Large Millimeter Array, the Square Kilometre Array, and the Thirty Meter Telescope, as well as Canada's national astronomy data centre.
The institute is also involved in the development and construction of instruments and telescopes.
Members of NRC-HAA are currently involved in The Next Generation Virgo Cluster Survey.
Members of NRC-HAA are currently involved with Pan-Andromeda Archaeological Survey.
Plaskett Fellowship
The Plaskett Fellowship is named after John Stanley Plaskett and is awarded to an outstanding, recent doctoral graduate in astrophysics or a closely related discipline. Fellows conduct independent research in a stimulating, collegial environment at the Dominion Astrophysical Observatory in Victoria, British Columbia, Canada. Expertise in observational astrophysics is the norm, but some theoreticians were also among this distinguished group of astronomers.
Covington Fellowship
The Covington Fellowship is named after Arthur Covington and is awarded to an outstanding, recent doctoral graduate in astrophysics or a closely related discipline. Fellows conduct independent research in a stimulating, collegial environment at the institute at the Dominion Radio Astrophysical Observatory in Penticton, BC. DRAO staff expertise is in observational radio astronomy and the development of instrumentation and technology for radio telescopes. Current and past Covington Fellows are:
See also
Atacama Large Millimeter Array
Canada–France–Hawaii Telescope
Dominion Radio Astrophysical Observatory
Gemini Observatory
James Clerk Maxwell Telescope
Square Kilometre Array
Thirty Meter Telescope
James Webb Space Telescope
References
External links
National science infrastructure (NRC Herzberg)
Herzberg Astrophysics Researchers
National Research Council (Canada)
Research institutes in Canada
Astronomy institutes and departments
Astrophysics research institutes
1975 establishments in Ontario
Organizations based in Victoria, British Columbia | NRC Herzberg Astronomy and Astrophysics Research Centre | Physics,Astronomy | 525 |
16,702,705 | https://en.wikipedia.org/wiki/Dispersive%20adhesion | Dispersive adhesion, also called adsorptive adhesion, is a mechanism for adhesion which attributes attractive forces between two materials to intermolecular interactions between molecules of each material. This mechanism is widely viewed as the most important of the five mechanisms of adhesion due to its presence in every type of adhesive system and its relative strength.
Source of dispersive adhesion attractions
The source of adhesive forces, according to the dispersive adhesion mechanism, is the weak interactions that occur between molecules close together. These interactions include London dispersion forces, Keesom forces, Debye forces and hydrogen bonds. Individually, these attractions are not very strong, but when summed over the bulk of a material, they can become significant.
London dispersion
London dispersion forces arise from instantaneous dipoles between two nonpolar molecules close together. The random nature of electron orbit allows moments in which the charge distribution in a molecule is unevenly distributed, allowing an electrostatic attraction to another molecule with a temporary dipole. A larger molecule allows for a larger dipole, and thus will have stronger dispersion forces.
Keesom
Keesom forces, also known as dipole–dipole interactions, result from two molecules that have permanent dipoles due to electronegativity differences between atoms in the molecule. This dipole causes a coulombic attraction between the two molecules.
Debye
Debye forces, or dipole–induced dipole interactions, can also play a role in dispersive adhesion. These come about when a nonpolar molecule becomes temporarily polarized due to interaction with a nearby polar molecule. This "induced dipole" in the nonpolar molecule then is attracted to the permanent dipole, yielding a Debye attraction.
Hydrogen bonding
Sometimes grouped into the chemical mechanism of adhesion, hydrogen bonding can increase adhesive strength by the dispersive mechanism. Hydrogen bonding occurs between molecules with a hydrogen atom attached to a small, electronegative atom such as fluorine, oxygen or nitrogen. This bond is naturally polar, with the hydrogen atom gaining a slight positive charge and the other atom becoming slightly negative. Two molecules, or even two functional groups on one large molecule, may then be attracted to each other via Keesom forces.
Factors affecting adhesion strength
The strength of adhesion by the dispersive mechanism depends on a variety of factors, including the chemical structure of the molecules involved in the adhesive system, the degree to which coatings wet each other, and the surface roughness at the interface.
Chemical composition
The chemical structure of the materials involved in a given adhesive system plays a large role in the adhesion of the system as a whole because the structure determines the type and strength of the intermolecular interactions present. All things equal, larger molecules, which experience higher dispersion forces, will have a larger adhesive strength than smaller molecules of the same basic chemical fingerprint. Similarly, polar molecules will have Keesom and Debye forces not experienced by nonpolar molecules of similar size. Compounds which can hydrogen bond across the adhesive interface will have even greater adhesive strength.
Wetting
Wetting is a measure of the thermodynamic compatibility of two surfaces. If the surfaces are well-matched, the surfaces will "desire" to interact with each other, minimizing the surface energy of both phases, and the surfaces will come into close contact. Because the intermolecular attractions strongly correlate with distance, the closer the interacting molecules are together, the stronger the attraction. Thus, two materials that wet well and have a large amount of surface area in contact will have stronger intermolecular attractions and a larger adhesive strength due to the dispersive mechanism.
Roughness
Surface roughness can also affect the adhesive strength. Surfaces with roughness on the scale of 1–2 micrometres can yield better wetting because they have a larger surface area. Thus, more intermolecular interactions at closer distances can arise, yielding stronger attractions and larger adhesive strength. Once the roughness becomes larger, on the order of 10 micrometres, the coating can no longer wet effectively, resulting in less contact area and a smaller adhesive strength.
Macroscopic shape
Adhesive strength depends also on the size and macroscopic shape of adhesive contact. When a rigid punch with a flat but oddly shaped face is carefully pulled off its soft counterpart, the detachment does not occur instantaneously. Instead, detachment fronts start at pointed corners and travel inwards until the final configuration is reached. The main parameter determining the adhesive strength of flat contacts appears to be the maximum linear size of the contact. The process of detachment can as observed experimentally can be seen in the film.
Systems dominated by dispersive adhesion
All materials, even those not usually classified as adhesives, experience an attraction to other materials simply due to dispersion forces. In many situations, these attractions are trivial; however, dispersive adhesion plays a dominant role in various adhesive systems, especially when multiple forms of intermolecular attractions are present. It has been shown by experimental methods that the dispersive mechanism of adhesion plays a large role in the overall adhesion of polymeric systems in particular.
See also
Adhesion
Intermolecular force
Van der Waals forces
Hydrogen bonding
References
Intermolecular forces
Articles containing video clips | Dispersive adhesion | Chemistry,Materials_science,Engineering | 1,110 |
39,171,284 | https://en.wikipedia.org/wiki/Dirac%20equation%20in%20curved%20spacetime | In mathematical physics, the Dirac equation in curved spacetime is a generalization of the Dirac equation from flat spacetime (Minkowski space) to curved spacetime, a general Lorentzian manifold.
Mathematical formulation
Spacetime
In full generality the equation can be defined on or a pseudo-Riemannian manifold, but for concreteness we restrict to pseudo-Riemannian manifold with signature . The metric is referred to as , or in abstract index notation.
Frame fields
We use a set of vierbein or frame fields , which are a set of vector fields (which are not necessarily defined globally on ). Their defining equation is
The vierbein defines a local rest frame, allowing the constant Gamma matrices to act at each spacetime point.
In differential-geometric language, the vierbein is equivalent to a section of the frame bundle, and so defines a local trivialization of the frame bundle.
Spin connection
To write down the equation we also need the spin connection, also known as the connection (1-)form. The dual frame fields have defining relation
The connection 1-form is then
where is a covariant derivative, or equivalently a choice of connection on the frame bundle, most often taken to be the Levi-Civita connection.
One should be careful not to treat the abstract Latin indices and Greek indices as the same, and further to note that neither of these are coordinate indices: it can be verified that doesn't transform as a tensor under a change of coordinates.
Mathematically, the frame fields define an isomorphism at each point where they are defined from the tangent space to . Then abstract indices label the tangent space, while greek indices label . If the frame fields are position dependent then greek indices do not necessarily transform tensorially under a change of coordinates.
Raising and lowering indices is done with for latin indices and for greek indices.
The connection form can be viewed as a more abstract connection on a principal bundle, specifically on the frame bundle, which is defined on any smooth manifold, but which restricts to an orthonormal frame bundle on pseudo-Riemannian manifolds.
The connection form with respect to frame fields defined locally is, in differential-geometric language, the connection with respect to a local trivialization.
Clifford algebra
Just as with the Dirac equation on flat spacetime, we make use of the Clifford algebra, a set of four gamma matrices satisfying
where is the anticommutator.
They can be used to construct a representation of the Lorentz algebra: defining
,
where is the commutator.
It can be shown they satisfy the commutation relations of the Lorentz algebra:
They therefore are the generators of a representation of the Lorentz algebra . But they do not generate a representation of the Lorentz group , just as the Pauli matrices generate a representation of the rotation algebra but not . They in fact form a representation of However, it is a standard abuse of terminology to any representations of the Lorentz algebra as representations of the Lorentz group, even if they do not arise as representations of the Lorentz group.
The representation space is isomorphic to as a vector space. In the classification of Lorentz group representations, the representation is labelled .
The abuse of terminology extends to forming this representation at the group level. We can write a finite Lorentz transformation on as
where is the standard basis for the Lorentz algebra. These generators have components
or, with both indices up or both indices down, simply matrices which have in the index and in the index, and 0 everywhere else.
If another representation has generators then we write
where are indices for the representation space.
In the case , without being given generator components for , this is not well defined: there are sets of generator components which give the same but different
Covariant derivative for fields in a representation of the Lorentz group
Given a coordinate frame arising from say coordinates , the partial derivative with respect to a general orthonormal frame is defined
and connection components with respect to a general orthonormal frame are
These components do not transform tensorially under a change of frame, but do when combined. Also, these are definitions rather than saying that these objects can arise as partial derivatives in some coordinate chart. In general there are non-coordinate orthonormal frames, for which the commutator of vector fields is non-vanishing.
It can be checked that under the transformation
if we define the covariant derivative
,
then transforms as
This generalises to any representation for the Lorentz group: if is a vector field for the associated representation,
When is the fundamental representation for , this recovers the familiar covariant derivative for (tangent-)vector fields, of which the Levi-Civita connection is an example.
There are some subtleties in what kind of mathematical object the different types of covariant derivative are. The covariant derivative in a coordinate basis is a vector-valued 1-form, which at each point is an element of . The covariant derivative in an orthonormal basis uses the orthonormal frame to identify the vector-valued 1-form with a vector-valued dual vector which at each point is an element of using that canonically. We can then contract this with a gamma matrix 4-vector which takes values at in
Dirac equation on curved spacetime
Recalling the Dirac equation on flat spacetime,
the Dirac equation on curved spacetime can be written down by promoting the partial derivative to a covariant one.
In this way, Dirac's equation takes the following form in curved spacetime:
where is a spinor field on spacetime. Mathematically, this is a section of a vector bundle associated to the spin-frame bundle by the representation
Recovering the Klein–Gordon equation from the Dirac equation
The modified Klein–Gordon equation obtained by squaring the operator in the Dirac equation, first found by Erwin Schrödinger as cited by Pollock
is given by
where is the Ricci scalar, and is the field strength of . An alternative version of the Dirac equation whose Dirac operator remains the square root of the Laplacian is given by the Dirac–Kähler equation; the price to pay is the loss of Lorentz invariance in curved spacetime.
Note that here Latin indices denote the "Lorentzian" vierbein labels while Greek indices denote manifold coordinate indices.
Action formulation
We can formulate this theory in terms of an action. If in addition the spacetime is orientable, there is a preferred orientation known as the volume form .
One can integrate functions against the volume form:
The function
is integrated against the volume form to obtain the Dirac action
See also
Dirac equation in the algebra of physical space
Dirac spinor
Maxwell's equations in curved spacetime
Two-body Dirac equations
References
Quantum field theory
Spinors
Partial differential equations
Fermions
Curved spacetime | Dirac equation in curved spacetime | Physics,Materials_science | 1,412 |
59,131,716 | https://en.wikipedia.org/wiki/Maurice%20Zucrow | Maurice Joseph Zucrow (December 15, 1899 – June 1975) was a Russian-born American scientist and aerospace engineer known for his contributions to the development of gas turbines and jet propulsion. Zucrow was born in Kiev in Tsarist Russia and immigrated with his family to the United Kingdom in 1900. Young Maurice attended Central Foundation Boys' School in London. The family moved to the US in 1914.
In 1922 Maurice Zucrow became the first person to graduate with a BS degree in engineering from Harvard University. He went on to receive a S.M degree from the same school next year. Zucrow was also the first recipient of a doctoral degree in engineering at Purdue University completing his dissertation in Mechanical Engineering in 1928. His PhD advisor was Andrey Abraham Potter, Dean of Purdue University College of Engineering.
After leaving Purdue in 1929, Zucrow spent 17 years in industry. During his work at Elliott Company, he played an important part in the research and development of the nation's first gas turbine built in 1942. He also helped develop Aerojet’s JATO rocket, used by seaplanes to assist takeoff under adverse conditions. During the World War II, Zucrow was asked to teach a course in jet propulsion theory to engineers in the aircraft industry as part of the Engineering, Science, and Management War Training (ESMWT) program at the University of California, Los Angeles.
In 1946 he joined the faculty of Purdue School of Aeronautics and Astronautics establishing Purdue's Jet Propulsion Center. The research facility was renamed Maurice J. Zucrow Propulsion Laboratories in 1998 and is now the world's largest academic propulsion laboratory. In 1948 Zucrow published Principles of Jet Propulsion and Gas Turbines, the first textbook in this field.
In 1957 Zucrow was elected to the board of directors of American Rocket Society together with Wernher von Braun. In 1962 Zucrow received the Sigma Xi national research award and delivered the award lecture entitled "Space Propulsion Engines - Their Characteristics and Problems". He received the Distinguished Civilian Service award from the Department of the Army in 1967.
Zucrow's residence in West Lafayette was 801 Carrolton Boulevard in Hill and Dales neighborhood adjacent to the Purdue campus.
Books
Zucrow, M.J., Principles of Jet Propulsion and Gas Turbines, John Wiley & Sons, 1948.
Zucrow, M.J., Aircraft and Missile Propulsion Volume 1: Thermodynamics of Fluid Flow and Application to Propulsion Engines, John Wiley and Sons, 1958.
Zucrow, M.J., Aircraft & Missile Propulsion, Volume 2: The Gas Turbine Power Plant, the Turboprop, Turbojet, Ramjet, and Rocket Engines, John Wiley and Sons; First edition, 1958.
Zucrow, M.J., Gas Dynamics, Volumes 1 and 2, John Wiley & Sons, 1976.
References
External links
, Maurice J. Zucrow Propulsion Laboratories at Purdue University
, Online books by Maurice J. Zucrow
, Maurice J. Zucrow papers at Purdue Archives
American scientists
1899 births
1975 deaths
Purdue University College of Engineering alumni
Purdue University faculty
Aerospace engineers
Harvard John A. Paulson School of Engineering and Applied Sciences alumni
Members of the American Rocket Society
Emigrants from the Russian Empire to the United States | Maurice Zucrow | Engineering | 648 |
2,542,927 | https://en.wikipedia.org/wiki/Content%20reference%20identifier |
Overview
A content reference identifier or CRID is a concept from the standardization work done by the TV-Anytime forum. It is or closely matches the concept of the Uniform Resource Locator, or URL, as used on the World-Wide Web:
The concept of CRID permits referencing contents unambiguously, regardless of their location, i.e., without knowing specific broadcast information (time, date and channel) or how to obtain them through a network, for instance, by means of a streaming service or by downloading a file from an Internet server.
The receiver must be capable of resolving these unambiguous references, i.e. of translating them into specific data that will allow it to obtain the location of that content in order to acquire it. This makes it possible for recording processes to take place without knowing that information, and even without knowing beforehand the duration of the content to be recorded: a complete series by a simple click, a program that has not been scheduled yet, a set of programs grouped by a specific criterion…
This framework allows for the separation between the reference to a given content (the CRID) and the necessary information to acquire it, which is called a “locator”. Each CRID may lead to one or more locators which will represent different copies of the same content. They may be identical copies broadcast in different channels or dates, or cost different prices. They may also be distinct copies with different technical parameters such as format or quality.
It may also be the case that the resolution process of a CRID provides another CRID as a result (for example, its reference in a different network, where it has an alternative identifier assigned by a different operator) or a set of CRIDs (for instance, if the original CRID represents a TV series, in which case the resolution process would result in the list of CRIDs representing each episode).
From the above it can be concluded that provided that a given content can belong to many groups (each possibly defined by distinctive qualities), it is possible that many CRIDs carry the same content. That is, several CRIDs may be resolved into the same locator.
A CRID is not exactly a universal, unique and exclusive identifier for a given content. It is closely related to the authority that creates it, to the resolution service provider, and to the content provider in such a way that the same content may have different CRIDs depending on the field in which they are used (for example, a different one for each television operator that has the rights to broadcast the content).
Format
A CRID is specified much like URLs. In fact, a CRID is a so-called URI. Typically, the content creator, the broadcaster or a third party will use their DNS-names in a combination with a product-specific name to create globally unique CRIDs. That is, the syntax of a CRID is:
crid://authority/data
The authority field represents the entity that created the CRID and its format is that of a DNS name. The data field represents a string of characters that will unambiguously identify the content within the authority scope (it is a string of characters assigned by the authority itself).
As an example, let's assume that BBC wanted to make a CRID for (all the programs of) the Olympics in China. It may have looked something like this
crid://bbc.co.uk/olympics/2008/
This would be a group CRID, that is, a CRID representing a group of contents. Then, to refer to a specific event – such as the women's shot-put final – they could have used the following inside their metadata.
crid://bbc.co.uk/olympics/2008/final/shotput/women
Currently, four types of CRIDs are playing a major role in some unidirectional television networks: programme CRID, series CRID, group CRID, and recommendation CRID. One of the most important applications of CRIDs is the so-called series link recording function (SL) of modern digital video recorders (DVR, PVR).
In turn, a locator is a string of characters that contains all the necessary information for a receiver to find and acquire a given content, whether it is received through a transport stream, located in local storage, downloaded as a file from an Internet server, or through a streaming service. For example, a DVB locator will include all the necessary parameters to identify a specific content within a transport stream: network, transport stream, service, table and/or event identifiers.
The locators' format, as established in TV-Anytime, is quite generic and simple, and corresponds to:
[transport-mechanism]:[specific-data]
The first part of the locator’s format (the transport mechanism) must be a string of characters that is unique for each mechanism (transport stream, local file, HTTP Internet access…). The second part must be unambiguous only within the scope of a given transport mechanism and will be standardized by the organism in charge of the regulation of the mechanism itself.
For instance, a DVB locator to identify a content within the transport stream of networks that follow this standard would be:
dvb://112.4a2.5ec;2d22~20121212T220000Z—PT01H30M
which would indicate a content (identified by the string “2d22”) that airs on a channel available on a DVB network identified by the address “112.4a2.5ec” (network “112”, transport stream “4a2” and service “5ec”), on 12 December 2012 at 10 p.m. and with a duration of 90 minutes.
The location resolution process
The location resolution process is the procedure by which, starting from the CRID of a given content, one or several locators of that content are obtained. Resolving a CRID can be a direct process, which leads immediately to one or many locators, or it may also happen that in the first place one or many intermediate CRIDs are returned, which must undergo the same procedure to finally obtain one or several locators.
This procedure involves some information elements, among which we find two structures named resolving authority record (RAR) and ContentReferencingTable, respectively. Consulting them repeatedly will take the receiver from a CRID to one or many locators that will allow it to acquire the content.
The RAR table
The RAR table is one or many data structures that provide the receiver, for each authority that submits CRIDs, information on the corresponding resolution service provider. Among other things, it informs about which mechanism is used to provide information to resolve the CRIDs from each authority. That is, one or many RAR records must exist for each authority that indicate the receiver where it has to go to resolve the CRIDs of that particular authority.
For example, in the record of the figure (expressed by means of a XML structure, according to the XML Schema defined in the TV-Anytime) there is an authority called “tve.es”, whose resolution service provider is the entity “rtve.es”, available on the URL "http://tva.rtve.es/locres/tve", which means there is resolution information in that URL.
These RAR records will have reached the receiver in an indefinite form, unimportant for the TV-Anytime specification, which will depend on the specific transport mechanism of the network to which the receiver is connected. Each family of standards that regulates distribution networks (DVB, ATSC, ISDB, IPTV...) will have previously defined such procedure, which will be used by devices certified according to those standards.
The ContentReferencingTable table
The second structure involved in the location resolution process is a proper resolution table which, given a content's CRID, returns one or several locators that enable the receiver to access an instance of that content, or one or many CRIDs that allow it to move forward in the resolution process.
The figure shows an example of this second structure, an XML document according to the specifications of the XML Schema defined in TV-Anytime. In it, several sections are included (<Result> elements) that structure the information that describes each resolution case.
The first one declares how a CRID (crid://tv.com/Friends/all), which corresponds to a group content that encompasses several episodes (two) of the “Friends” series is resolved. The result of the resolution process provides two new CRIDs each of them corresponding to one of the two episodes.
The second <Result> element resolves the CRID of the first episode of the first season. The result of the resolution process is two DVB locators. The “acquire” attribute with “any” value indicates that any of them are good (the second one is a repetition broadcast a week later).
The third <Result> element gives information about the second episode. It indicates that it cannot be resolved yet (“status” attribute with the “cannot yet resolve” value), indicating a date on which the request for resolution information must be repeated.
The process
Once the user has selected a given content (identified by the corresponding CRID) to perform some action upon it, the receiver begins the location resolution process that shall lead to specific location information that allows access to a copy of the content.
This procedure depends mainly on the receiver’s connectivity. It is possible to make a basic distinction between unidirectional networks, where the receiver can only receive information through the broadcast channel, and bidirectional networks, where there is also a return channel through which the receiver can communicate with the outside (typically an Internet access).
For receivers connected only to a broadcast channel, it is clear that the resolution information must come directly from that channel, or be available somehow in an existing local storage system. After selecting a CRID, the first thing the receiver needs to do is check the information about where to find the resolution table. For this, it must find a RAR record associated with the authority of the selected CRID.
Once a RAR record corresponding to that authority is found, the receiver will know, by referring to the URL field, where to access (or, in this case, where to listen) to obtain the resolution information.
The information that will receive through that access point will consist of a message for each of the consulted CRIDs (for example, a <Result> element in the ContentReferencingTable).
In web casting
To make the CRID even more globally available the IETF will publish a request for comments specifying the use of the CRID over the web. This will allow consumer devices to hook up to content provider servers, much like current browsers look up webservers, requesting content by CRID.
In May 2005, an Informational RFC, No 4078, was published as the start of this work.
The long-term goal is that CRIDs should be available for use by cell phones, PDAs, digital TV receivers and other consumer devices for fetching content, either from a broadcast stream or over IP networks.
See also
BBC Programme Identifier
References
RFC 4078 (PDF) Accessed 27 October 2011
RFC 4078 (TXT) Accessed 27 October 2011
ETSI TS 102 822-2 V1.4.1 (2007–11), Page 19, Section 5: "TV-Anytime content referencing scenarios" Accessed 3 December 2012
ETSI TS 102 822-4 V1.7.1 (2012–12), Page 13, Section 8: "CRID" Accessed 9 January 2013
ETSI TS 102 323 V1.5.1 (2012-01), Page 27, Section 6: "CRIDs and other URIs in DVB networks" Accessed 1 March 2012
Television terminology
Interactive television
Digital video recorders
Digital television
Video storage
Digital media
Television time shifting technology
Digital Video Broadcasting
URI schemes
Broadcast engineering | Content reference identifier | Technology,Engineering | 2,505 |
40,816,101 | https://en.wikipedia.org/wiki/Today%20Trader | Today Trader, Inc is a trading and education service that started in 2008. As of 2013, trading with their service is done primarily through their relationship with the Ditto Trade online brokerage service. Since 2018, the venture serves as an educational hub.
History
Steve Gomez and Andy Lindloff met at a Level 2 trading seminar when they were both working as floor traders in 1998. Today Trader, Inc was started in 2008 when Gomez and Lindloff began sharing their desktops with other traders through GoToMeeting. This service was available as a subscription for active day traders.
The day trading transparency and education provided by Today Trader was unique and they were early adopters in 2010. The company utilized many social media resources to crowdsource ideas and share their ideas including YouTube, Twitter, and StockTwits.
Following the article in The New York Times, the company was approached by Brian Lund to consider becoming a "Lead Trader" with the online brokerage service Ditto Trade. Ditto Trade allows people to follow the Today Trader Lead Trader account and be included in every trade or trade alongside these "master traders" from trade alerts. In 2011, the company was performing approximately thirty transactions per month. These trades are primarily day and swing trading transactions. The service was launched later in 2010 and has been outperforming the S&P 500 since that time.
Gomez was interviewed by CNBC reporter Jane Wells after he sold a portion of his silver holdings in 2011.
On September 20, 2012, the Today Trader team discontinued their live trading service in favor of their relationship with Ditto Trade. They offer trading classes online to learn their specialized trading technique called "swing scalping". Gomez and Lindloff have also published on the importance on money management for traders.
Gomez was listed as one of the "Top 5 Trading Guru’s of 2013" by Trader Robotics.
In March 2018 Michael Hebenstreit, a stock broker from Germany, acquired Today Trader and converted the venture into an educational hub offering content and services for professional traders and students who want to learn trading.
Controversy
The Today Trader live trading service brought attention to the field of day trading. The Motley Fool author Rich Greifner argued that the day trading lifestyle and results described in The New York Times article was "impressive" but questioned the accuracy of the claim as well as offering that these results were "hardly indicative of the typical day trader's experience".
In a follow-up post, StockTwits founder Howard Lindzon described his dislike of the term "day trader" describing it as "tired" similar to the term "journalist". He also noted that traders Gomez "keep moving forward and adapt" to the current market conditions.
References
External links
TodayTrader website
TodayTrader on Twitter
TodayTrader on Youtube
Companies based in San Diego
Online financial services companies of the United States
Real-time web | Today Trader | Technology | 588 |
27,059 | https://en.wikipedia.org/wiki/Stainless%20steel | Stainless steel, also known as inox, corrosion-resistant steel (CRES), and rustless steel, is an iron-based alloy containing a minimum level of chromium that is resistant to rusting and corrosion. Stainless steel's resistance to corrosion results from the 10.5%, or more, chromium content which forms a passive film that can protect the material and self-heal in the presence of oxygen. It can also be alloyed with other elements such as molybdenum, carbon, nickel and nitrogen to develop a range of different properties depending on its specific use.
The alloy's properties, such as luster and resistance to corrosion, are useful in many applications. Stainless steel can be rolled into sheets, plates, bars, wire, and tubing. These can be used in cookware, cutlery, surgical instruments, major appliances, vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills, chemical plants, water treatment), and storage tanks and tankers for chemicals and food products. Some grades are also suitable for forging and casting.
The biological cleanability of stainless steel is superior to both aluminium and copper, and comparable to glass. Its cleanability, strength, and corrosion resistance have prompted the use of stainless steel in pharmaceutical and food processing plants.
Different types of stainless steel are labeled with an AISI three-digit number. The ISO 15510 standard lists the chemical compositions of stainless steels of the specifications in existing ISO, ASTM, EN, JIS, and GB standards in a useful interchange table.
Properties
Corrosion resistance
Although stainless steel does rust, this only affects the outer few layers of atoms, its chromium content shielding deeper layers from oxidation.
The addition of nitrogen also improves resistance to pitting corrosion and increases mechanical strength. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment the alloy must endure. Corrosion resistance can be increased further by the following means:
increasing chromium content to more than 11%
adding nickel to at least 8%
adding molybdenum (which also improves resistance to pitting corrosion)
Strength
The most common type of stainless steel, 304, has a tensile yield strength around in the annealed condition. It can be strengthened by cold working to a strength of in the full-hard condition.
The strongest commonly available stainless steels are precipitation hardening alloys such as 17-4 PH and Custom 465. These can be heat treated to have tensile yield strengths up to .
Melting point
Melting point of stainless steel is near that of ordinary steel, and much higher than the melting points of aluminium or copper.
As with most alloys, the melting point of stainless steel is expressed in the form of a range of temperatures, and not a single temperature. This temperature range goes from depending on the specific consistency of the alloy in question.
Conductivity
Like steel, stainless steels are relatively poor conductors of electricity, with significantly lower electrical conductivities than copper. In particular, the electrical contact resistance (ECR) of stainless steel arises as a result of the dense protective oxide layer and limits its functionality in applications as electrical connectors. Copper alloys and nickel-coated connectors tend to exhibit lower ECR values and are preferred materials for such applications. Nevertheless, stainless steel connectors are employed in situations where ECR poses a lower design criteria and corrosion resistance is required, for example in high temperatures and oxidizing environments.
Magnetism
Martensitic, duplex and ferritic stainless steels are magnetic, while austenitic stainless steel is usually non-magnetic. Ferritic steel owes its magnetism to its body-centered cubic crystal structure, in which iron atoms are arranged in cubes (with one iron atom at each corner) and an additional iron atom in the center. This central iron atom is responsible for ferritic steel's magnetic properties. This arrangement also limits the amount of carbon the steel can absorb to around 0.025%. Grades with low coercive field have been developed for electro-valves used in household appliances and for injection systems in internal combustion engines. Some applications require non-magnetic materials, such as magnetic resonance imaging. Austenitic stainless steels, which are usually non-magnetic, can be made slightly magnetic through work hardening. Sometimes, if austenitic steel is bent or cut, magnetism occurs along the edge of the stainless steel because the crystal structure rearranges itself.
Wear
Galling, sometimes called cold welding, is a form of severe adhesive wear, which can occur when two metal surfaces are in relative motion to each other and under heavy pressure. Austenitic stainless steel fasteners are particularly susceptible to thread galling, though other alloys that self-generate a protective oxide surface film, such as aluminum and titanium, are also susceptible. Under high contact-force sliding, this oxide can be deformed, broken, and removed from parts of the component, exposing the bare reactive metal. When the two surfaces are of the same material, these exposed surfaces can easily fuse. Separation of the two surfaces can result in surface tearing and even complete seizure of metal components or fasteners. Galling can be mitigated by the use of dissimilar materials (bronze against stainless steel) or using different stainless steels (martensitic against austenitic). Additionally, threaded joints may be lubricated to provide a film between the two parts and prevent galling. Nitronic 60, made by selective alloying with manganese, silicon, and nitrogen, has demonstrated a reduced tendency to gall.
Density
The density of stainless steel ranges from depending on the alloy.
History
The invention of stainless steel followed a series of scientific developments, starting in 1798 when chromium was first shown to the French Academy by Louis Vauquelin. In the early 1800s, British scientists James Stoddart, Michael Faraday, and Robert Mallet observed the resistance of chromium-iron alloys ("chromium steels") to oxidizing agents. Robert Bunsen discovered chromium's resistance to strong acids. The corrosion resistance of iron-chromium alloys may have been first recognized in 1821 by Pierre Berthier, who noted their resistance against attack by some acids and suggested their use in cutlery.
In the 1840s, both Britain's Sheffield steelmakers and then Krupp of Germany were producing chromium steel with the latter employing it for cannons in the 1850s. In 1861, Robert Forester Mushet took out a patent on chromium steel in Britain.
These events led to the first American production of chromium-containing steel by J. Baur of the Chrome Steel Works of Brooklyn for the construction of bridges. A US patent for the product was issued in 1869. This was followed with recognition of the corrosion resistance of chromium alloys by Englishmen John T. Woods and John Clark, who noted ranges of chromium from 5–30%, with added tungsten and "medium carbon". They pursued the commercial value of the innovation via a British patent for "Weather-Resistant Alloys".
Scientists researching steel corrosion in the second half of the 19th century didn't pay attention to the amount of carbon in the alloyed steels they were testing until in 1898 Adolphe Carnot and E. Goutal noted that chromium steels better resist to oxidation with acids the less carbon they contain.
Also in the late 1890s, German chemist Hans Goldschmidt developed an aluminothermic (thermite) process for producing carbon-free chromium. Between 1904 and 1911, several researchers, particularly Leon Guillet of France, prepared alloys that would be considered stainless steel today.
In 1908, the Essen firm Friedrich Krupp Germaniawerft built the 366-ton sailing yacht Germania featuring a chrome-nickel steel hull, in Germany. In 1911, Philip Monnartz reported on the relationship between chromium content and corrosion resistance. On 17 October 1912, Krupp engineers Benno Strauss and Eduard Maurer patented as Nirosta the austenitic stainless steel known today as 18/8 or AISI type 304.
Similar developments were taking place in the United States, where Christian Dantsizen of General Electric and Frederick Becket (1875–1942) at Union Carbide were industrializing ferritic stainless steel. In 1912, Elwood Haynes applied for a US patent on a martensitic stainless steel alloy, which was not granted until 1919.
Harry Brearley
While seeking a corrosion-resistant alloy for gun barrels in 1913, Harry Brearley of the Brown-Firth research laboratory in Sheffield, England, discovered and subsequently industrialized a martensitic stainless steel alloy, today known as AISI type 420. The discovery was announced two years later in a January 1915 newspaper article in The New York Times.
The metal was later marketed under the "Staybrite" brand by Firth Vickers in England and was used for the new entrance canopy for the Savoy Hotel in London in 1929. Brearley applied for a US patent during 1915 only to find that Haynes had already registered one. Brearley and Haynes pooled their funding and, with a group of investors, formed the American Stainless Steel Corporation, with headquarters in Pittsburgh, Pennsylvania.
Rustless steel
Brearley initially called his new alloy "rustless steel". The alloy was sold in the US under different brand names like "Allegheny metal" and "Nirosta steel". Even within the metallurgy industry, the name remained unsettled; in 1921, one trade journal called it "unstainable steel". Brearley worked with a local cutlery manufacturer, who gave it the name "stainless steel". As late as 1932, Ford Motor Company continued calling the alloy "rustless steel" in automobile promotional materials.
In 1929, before the Great Depression, over 25,000 tons of stainless steel were manufactured and sold in the US annually.
Major technological advances in the 1950s and 1960s allowed the production of large tonnages at an affordable cost:
AOD process (argon oxygen decarburization), for the removal of carbon and sulfur
Continuous casting and hot strip rolling
The Z-Mill, or Sendzimir cold rolling mill
The Creusot-Loire Uddeholm (CLU) and related processes which use steam instead of some or all of the argon
Families
Stainless steel is classified into five different "families" of alloys, each having a distinct set of attributes. Four of the families are defined by their predominant crystalline structure - the austenitic, ferritic, martensitic, and duplex alloys. The fifth family, precipitation hardening, is defined by the type of heat treatment used to develop its properties.
Austenitic
Austenitic stainless steel is the largest family of stainless steels, making up about two-thirds of all stainless steel production. They have a face-centered cubic crystal structure. This microstructure is achieved by alloying steel with sufficient nickel, manganese, or nitrogen to maintain an austenitic microstructure at all temperatures, ranging from the cryogenic region to the melting point. Thus, austenitic stainless steels are not hardenable by heat treatment since they possess the same microstructure at all temperatures.
Austenitic stainless steels consist of two subfamilies:
200 series are chromium-manganese-nickel alloys that maximize the use of manganese and nitrogen to minimize the use of nickel. Due to their nitrogen addition, they possess approximately 50% higher yield strength than 300-series stainless sheets of steel. Representative alloys include Type 201 and Type 202.
300 series are chromium-nickel alloys that achieve their austenitic microstructure almost exclusively by nickel alloying; some very highly alloyed grades include some nitrogen to reduce nickel requirements. 300 series is the largest group and the most widely used. Representative alloys include Type 304 and Type 316.
Ferritic
Ferritic stainless steels have a body-centered cubic crystal structure, are magnetic, and are hardenable by cold working, but not by heat treating. They contain between 10.5% and 27% chromium with very little or no nickel. Due to the near-absence of nickel, they are less expensive than austenitic stainless steels. Representative alloys include Type 409, Type 429, Type 430, and Type 446. Ferritic stainless steels are present in many products, which include:
Automobile exhaust pipes
Architectural and structural applications
Building components, such as slate hooks, roofing, and chimney ducts
Power plates in solid oxide fuel cells operating at temperatures around
Martensitic
Martensitic stainless steels have a body-centered tetragonal crystal structure, are magnetic, and are hardenable by heat treating and by cold working. They offer a wide range of properties and are used as stainless engineering steels, stainless tool steels, and creep-resistant steels. They are not as corrosion-resistant as ferritic and austenitic stainless steels due to their low chromium content. They fall into four categories (with some overlap):
Fe-Cr-C grades. These were the first grades used and are still widely used in engineering and wear-resistant applications. Representative grades include Type 410, Type 420, and Type 440C.
Fe-Cr-Ni-C grades. Some carbon is replaced by nickel. They offer higher toughness and higher corrosion resistance. Representative grades include Type 431.
Martensitic precipitation hardening grades. 17-4 PH (UNS S17400), the best-known grade, combines martensitic hardening and precipitation hardening to increase strength and toughness.
Creep-resisting grades. Small additions of niobium, vanadium, boron, and cobalt increase the strength and creep resistance up to about .
Martensitic stainless steels can be heat treated to provide better mechanical properties. The heat treatment typically involves three steps:
Austenitizing, in which the steel is heated to a temperature in the range , depending on grade. The resulting austenite has a face-centered cubic crystal structure.
Quenching. The austenite is transformed into martensite, a hard body-centered tetragonal crystal structure. The quenched martensite is very hard and too brittle for most applications. Some residual austenite may remain.
Tempering. Martensite is heated to around , held at temperature, then air-cooled. Higher tempering temperatures decrease yield strength and ultimate tensile strength but increase the elongation and impact resistance.
Duplex
Duplex stainless steels have a mixed microstructure of austenite and ferrite, the ideal ratio being a 50:50 mix, though commercial alloys may have ratios of 40:60. They are characterized by higher chromium (19–32%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. Duplex stainless steels have roughly twice the yield strength of austenitic stainless steel. Their mixed microstructure provides improved resistance to chloride stress corrosion cracking in comparison to austenitic stainless steel types 304 and 316. Duplex grades are usually divided into three sub-groups based on their corrosion resistance: lean duplex, standard duplex, and super duplex. The properties of duplex stainless steels are achieved with an overall lower alloy content than similar-performing super-austenitic grades, making their use cost-effective for many applications. The pulp and paper industry was one of the first to extensively use duplex stainless steel. Today, the oil and gas industry is the largest user and has pushed for more corrosion resistant grades, leading to the development of super duplex and hyper duplex grades. More recently, the less expensive (and slightly less corrosion-resistant) lean duplex has been developed, chiefly for structural applications in building and construction (concrete reinforcing bars, plates for bridges, coastal works) and in the water industry.
Precipitation hardening
Precipitation hardening stainless steels are characterized by the abiity to be precipitation hardened to higher strength. There are three types of precipitation hardening stainless steels which are classified according to their crystalline structure:
Martensitic precipitation hardenable stainless steels are martensitic at room temperature in both the solution annealed and precipitation hardened conditions. Representative alloys include 17-4 PH (UNS S17400), 15-5 PH (UNS S15500), Custom 450 (UNS S45000) and Custom 465 (UNS S46500).
Semi-austenitic precipitation hardenable stainless steels are initially austenitic in the solution annealed condition for ease of fabrication, but are subsequently transformed to martensite to provide higher strength and to be precipitation hardened. Representative alloys include 17-7 PH (UNS S17700), 15-7 PH (UNS S15700), AM-350 (UNS S35000), and AM-355 (UNS S35500).
Austenitic precipitation hardenable stainless steels are austenitic at room temperature in both the solution annealed and precipitation hardened conditions. Representative alloys include A-286 (UNS S66286) and Discalloy (UNS S66220).
Classification systems
Several different classification systems have been developed for designating stainless steels. The main system used in the United States has been the SAE steel grades numbering system. The SAE numbering system designates stainless steels by "Type" followed by a three-digit number and sometimes a letter suffix. A newer system that was jointly developed by ASTM and SAE in 1974 is The Unified Numbering System for Metals and Alloys (UNS). The Unified Numbering System classifies stainless steels using an alpha-numeric identifier consisting of "S" followed by five digits, although some austenitic stainless steels with high nickel content may fall into the nickel-base designation which uses "N" as the alpha identifer. The UNS designations incorporate previously used designations, whether from the SAE numbering system or proprietary alloy designations. Europe has adopted EN 10088 for classification of stainless steels.
Corrosion resistance
Unlike carbon steel, stainless steels do not suffer uniform corrosion when exposed to wet environments. Unprotected carbon steel rusts readily when exposed to a combination of air and moisture. The resulting iron oxide surface layer is porous and fragile. In addition, as iron oxide occupies a larger volume than the original steel, this layer expands and tends to flake and fall away, exposing the underlying steel to further attack. In comparison, stainless steels contain sufficient chromium to undergo passivation, spontaneously forming a microscopically thin inert surface film of chromium oxide by reaction with the oxygen in the air and even the small amount of dissolved oxygen in the water. This passive film prevents further corrosion by blocking oxygen diffusion to the steel surface and thus prevents corrosion from spreading into the bulk of the metal. This film is self-repairing, even when scratched or temporarily disturbed by conditions that exceed the inherent corrosion resistance of that grade.
The resistance of this film to corrosion depends upon the chemical composition of the stainless steel, chiefly the chromium content. It is customary to distinguish between four forms of corrosion: uniform, localized (pitting), galvanic, and SCC (stress corrosion cracking). Any of these forms of corrosion can occur when the grade of stainless steel is not suited for the working environment.
Uniform
Uniform corrosion takes place in very aggressive environments, typically where chemicals are produced or heavily used, such as in the pulp and paper industries. The entire surface of the steel is attacked, and the corrosion is expressed as corrosion rate in mm/year (usually less than 0.1 mm/year is acceptable for such cases). Corrosion tables provide guidelines.
This is typically the case when stainless steels are exposed to acidic or basic solutions. Whether stainless steel corrodes depends on the kind and concentration of acid or base and the solution temperature. Uniform corrosion is typically easy to avoid because of extensive published corrosion data or easily performed laboratory corrosion testing.
Acidic solutions can be put into two general categories: reducing acids, such as hydrochloric acid and dilute sulfuric acid, and oxidizing acids, such as nitric acid and concentrated sulfuric acid. Increasing chromium and molybdenum content provides increased resistance to reducing acids while increasing chromium and silicon content provides increased resistance to oxidizing acids. Sulfuric acid is one of the most-produced industrial chemicals. At room temperature, type 304 stainless steel is only resistant to 3% acid, while type 316 is resistant to 3% acid up to and 20% acid at room temperature. Thus type 304 SS is rarely used in contact with sulfuric acid. Type 904L and Alloy 20 are resistant to sulfuric acid at even higher concentrations above room temperature. Concentrated sulfuric acid possesses oxidizing characteristics like nitric acid, and thus silicon-bearing stainless steels are also useful. Hydrochloric acid damages any kind of stainless steel and should be avoided. All types of stainless steel resist attack from phosphoric acid and nitric acid at room temperature. At high concentrations and elevated temperatures, attack will occur, and higher-alloy stainless steels are required. In general, organic acids are less corrosive than mineral acids such as hydrochloric and sulfuric acid.
Type 304 and type 316 stainless steels are unaffected by weak bases such as ammonium hydroxide, even in high concentrations and at high temperatures. The same grades exposed to stronger bases such as sodium hydroxide at high concentrations and high temperatures will likely experience some etching and cracking. Increasing chromium and nickel contents provide increased resistance.
All grades resist damage from aldehydes and amines, though in the latter case type 316 is preferable to type 304; cellulose acetate damages type 304 unless the temperature is kept low. Fats and fatty acids only affect type 304 at temperatures above and type 316 SS above , while type 317 SS is unaffected at all temperatures. Type 316L is required for the processing of urea.
Localized
Localized corrosion can occur in several ways, e.g. pitting corrosion and crevice corrosion. These localized attacks are most common in the presence of chloride ions. Higher chloride levels require more highly alloyed stainless steels.
Localized corrosion can be difficult to predict because it is dependent on many factors, including:
Chloride ion concentration. Even when chloride solution concentration is known, it is still possible for localized corrosion to occur unexpectedly. Chloride ions can become unevenly concentrated in certain areas, such as in crevices (e.g. under gaskets) or on surfaces in vapor spaces due to evaporation and condensation.
Temperature: increasing temperature increases susceptibility.
Acidity: increasing acidity increases susceptibility.
Stagnation: stagnant conditions increase susceptibility.
Oxidizing species: the presence of oxidizing species, such as ferric and cupric ions, increases susceptibility.
Pitting corrosion is considered the most common form of localized corrosion. The corrosion resistance of stainless steels to pitting corrosion is often expressed by the PREN, obtained through the formula:
,
where the terms correspond to the proportion of the contents by mass of chromium, molybdenum, and nitrogen in the steel. For example, if the steel consisted of 15% chromium %Cr would be equal to 15.
The higher the PREN, the higher the pitting corrosion resistance. Thus, increasing chromium, molybdenum, and nitrogen contents provide better resistance to pitting corrosion.
Though the PREN of certain steel may be theoretically sufficient to resist pitting corrosion, crevice corrosion can still occur when the poor design has created confined areas (overlapping plates, washer-plate interfaces, etc.) or when deposits form on the material. In these select areas, the PREN may not be high enough for the service conditions. Good design, fabrication techniques, alloy selection, proper operating conditions based on the concentration of active compounds present in the solution causing corrosion, pH, etc. can prevent such corrosion.
Stress
Stress corrosion cracking (SCC) is caused by combination of tensile stress and a corrosive environment and can lead to unexpected and sudden failure of a stainless steel component. It may occur when three conditions are met:
The part contains either applied or residual tensile stresses.
The part is in a corrosive environment.
The stainless steel is susceptible to SCC.
SCC can be prevented by eliminating one of these three conditions.
The SCC mechanism results from the following sequence of events:
Pitting occurs.
Cracks start from a pit initiation site.
Cracks then propagate through the metal in a transgranular or intergranular mode.
Failure occurs.
Galvanic
Galvanic corrosion (also called "dissimilar-metal corrosion") refers to corrosion damage induced when two dissimilar materials are coupled in a corrosive electrolyte. The most common electrolyte is water, ranging from freshwater to seawater. When a galvanic couple forms, one of the metals in the couple becomes the anode and corrodes faster than it would alone, while the other becomes the cathode and corrodes slower than it would alone. Stainless steel, due to having a more positive electrode potential than for example carbon steel and aluminium, becomes the cathode, accelerating the corrosion of the anodic metal. An example is the corrosion of aluminium rivets fastening stainless steel sheets in contact with water. The relative surface areas of the anode and the cathode are important in determining the rate of corrosion. In the above example, the surface area of the rivets is small compared to that of the stainless steel sheet, resulting in rapid corrosion. However, if stainless steel fasteners are used to assemble aluminium sheets, galvanic corrosion will be much slower because the galvanic current density on the aluminium surface will be many orders of magnitude smaller. A frequent mistake is to assemble stainless steel plates with carbon steel fasteners; whereas using stainless steel to fasten carbon-steel plates is usually acceptable, the reverse is not. Providing electrical insulation between the dissimilar metals, where possible, is effective at preventing this type of corrosion.
High-temperature
At elevated temperatures, all metals react with hot gases. The most common high-temperature gaseous mixture is air, of which oxygen is the most reactive component. To avoid corrosion in air, carbon steel is limited to approximately . Oxidation resistance in stainless steels increases with additions of chromium, silicon, and aluminium. Small additions of cerium and yttrium increase the adhesion of the oxide layer on the surface. The addition of chromium remains the most common method to increase high-temperature corrosion resistance in stainless steels; chromium reacts with oxygen to form a chromium oxide scale, which reduces oxygen diffusion into the material. The minimum 10.5% chromium in stainless steels provides resistance to approximately , while 16% chromium provides resistance up to approximately . Type 304, the most common grade of stainless steel with 18% chromium, is resistant to approximately . Other gases, such as sulfur dioxide, hydrogen sulfide, carbon monoxide, chlorine, also attack stainless steel. Resistance to other gases is dependent on the type of gas, the temperature, and the alloying content of the stainless steel. With the addition of up to 5% aluminium, ferritic grades Fe-Cr-Al are designed for electrical resistance and oxidation resistance at elevated temperatures. Such alloys include Kanthal, produced in the form of wire or ribbons.
Standard finishes
Standard mill finishes can be applied to flat rolled stainless steel directly by the rollers and by mechanical abrasives. Steel is first rolled to size and thickness and then annealed to change the properties of the final material. Any oxidation that forms on the surface (mill scale) is removed by pickling, and a passivation layer is created on the surface. A final finish can then be applied to achieve the desired aesthetic appearance.
The following designations are used in the U.S. to describe stainless steel finishes by ASTM A480/A480M-18 (DIN):
No. 0: Hot-rolled, annealed, thicker plates
No. 1 (1D): Hot-rolled, annealed and passivated
No. 2D (2D): Cold rolled, annealed, pickled and passivated
No. 2B (2B): Same as above with additional pass through highly polished rollers
No. 2BA (2R): Bright annealed (BA or 2R) same as above then bright annealed under oxygen-free atmospheric condition
No. 3 (G-2G:) Coarse abrasive finish applied mechanically
No. 4 (1J-2J): Brushed finish
No. 5: Satin finish
No. 6 (1K-2K): Matte finish (brushed but smoother than #4)
No. 7 (1P-2P): Reflective finish
No. 8: Mirror finish
No. 9: Bead blast finish
No. 10: Heat colored finish – offering a wide range of electropolished and heat colored surfaces
Joining
A wide range of joining processes are available for stainless steels, though welding is by far the most common.
The ease of welding largely depends on the type of stainless steel used. Austenitic stainless steels are the easiest to weld by electric arc, with weld properties similar to those of the base metal (not cold-worked). Martensitic stainless steels can also be welded by electric-arc but, as the heat-affected zone (HAZ) and the fusion zone (FZ) form martensite upon cooling, precautions must be taken to avoid cracking of the weld. Improper welding practices can additionally cause sugaring (oxide scaling) and heat tint on the backside of the weld. This can be prevented with the use of back-purging gases, backing plates, and fluxes. Post-weld heat treatment is almost always required while preheating before welding is also necessary in some cases. Electric arc welding of type 430 ferritic stainless steel results in grain growth in the HAZ, which leads to brittleness. This has largely been overcome with stabilized ferritic grades, where niobium, titanium, and zirconium form precipitates that prevent grain growth. Duplex stainless steel welding by electric arc is a common practice but requires careful control of the process parameters. Otherwise, the precipitation of unwanted intermetallic phases occurs, which reduces the toughness of the welds.
Electric arc welding processes include:
Gas metal arc welding, also known as MIG/MAG welding
Gas tungsten arc welding, also known as tungsten inert gas (TIG) welding
Plasma arc welding
Flux-cored arc welding
Shielded metal arc welding (covered electrode)
Submerged arc welding
MIG, MAG and TIG welding are the most common methods.
Other welding processes include:
Stud welding
Resistance spot welding
Resistance seam welding
Flash welding
Laser beam welding
Oxy-acetylene welding
Stainless steel may be bonded with adhesives such as silicone, silyl modified polymers, and epoxies. Acrylic and polyurethane adhesives are also used in some situations.
Production
Most of the world's stainless steel production is produced by the following processes:
Electric arc furnace (EAF): stainless steel scrap, other ferrous scrap, and ferrous alloys (Fe Cr, Fe Ni, Fe Mo, Fe Si) are melted together. The molten metal is then poured into a ladle and transferred into the AOD process (see below).
Argon oxygen decarburization (AOD): carbon in the molten steel is removed (by turning it into carbon monoxide gas) and other compositional adjustments are made to achieve the desired chemical composition.
Continuous casting (CC): the molten metal is solidified into slabs for flat products (a typical section is thick and wide) or blooms (sections vary widely but is the average size).
Hot rolling (HR): slabs and blooms are reheated in a furnace and hot-rolled. Hot rolling reduces the thickness of the slabs to produce about -thick coils. Blooms, on the other hand, are hot-rolled into bars, which are cut into lengths at the exit of the rolling mill, or wire rod, which is coiled.
Cold finishing (CF) depends on the type of product being finished:
Hot-rolled coils are pickled in acid solutions to remove the oxide scale on the surface, then subsequently cold rolled in Sendzimir rolling mills and annealed in a protective atmosphere until the desired thickness and surface finish is obtained. Further operations such as slitting and tube forming can be performed in downstream facilities.
Hot-rolled bars are straightened, then machined to the required tolerance and finish.
Wire rod coils are subsequently processed to produce cold-finished bars on drawing benches, fasteners on boltmaking machines, and wire on single or multipass drawing machines.
World stainless steel production figures are published yearly by the International Stainless Steel Forum. Of the EU production figures, Italy, Belgium and Spain were notable, while Canada and Mexico produced none. China, Japan, South Korea, Taiwan, India the US and Indonesia were large producers while Russia reported little production.
Breakdown of production by stainless steels families in 2017:
Austenitic stainless steels Cr-Ni (also called 300-series, see "Grades" section above): 54%
Austenitic stainless steels Cr-Mn (also called 200-series): 21%
Ferritic and martensitic stainless steels (also called 400-series): 23%
Applications
Stainless steel is used in a multitude of fields including architecture, art, chemical engineering, food and beverage manufacture, vehicles, medicine, energy and firearms.
Life cycle cost
Life cycle cost (LCC) calculations are used to select the design and the materials that will lead to the lowest cost over the whole life of a project, such as a building or a bridge.
The formula, in a simple form, is the following:
where LCC is the overall life cycle cost, AC is the acquisition cost, IC the installation cost, OC the operating and maintenance costs, LP the cost of lost production due to downtime, and RC the replacement materials cost.
In addition, N is the planned life of the project, i the interest rate, and n the year in which a particular OC or LP or RC is taking place. The interest rate (i) is used to convert expenses from different years to their present value (a method widely used by banks and insurance companies) so they can be added and compared fairly. The usage of the sum formula () captures the fact that expenses over the lifetime of a project must be cumulated after they are corrected for interest rate.
Application of LCC in materials selection
Stainless steel used in projects often results in lower LCC values compared to other materials. The higher acquisition cost (AC) of stainless steel components are often offset by improvements in operating and maintenance costs, reduced loss of production (LP) costs, and the higher resale value of stainless steel components.
LCC calculations are usually limited to the project itself. However, there may be other costs that a project stakeholder may wish to consider:
Utilities, such as power plants, water supply & wastewater treatment, and hospitals, cannot be shut down. Any maintenance will require extra costs associated with continuing service.
Indirect societal costs (with possible political fallout) may be incurred in some situations such as closing or reducing traffic on bridges, creating queues, delays, loss of working hours to the people, and increased pollution by idling vehicles.
Sustainability – recycling and reuse
The average carbon footprint of stainless steel (all grades, all countries) is estimated to be 2.90 kg of CO2 per kg of stainless steel produced, of which 1.92 kg are emissions from raw materials (Cr, Ni, Mo); 0.54 kg from electricity and steam, and 0.44 kg are direct emissions (i.e., by the stainless steel plant). Note that stainless steel produced in countries that use cleaner sources of electricity (such as France, which uses nuclear energy) will have a lower carbon footprint. Ferritics without Ni will have a lower CO2 footprint than austenitics with 8% Ni or more. Carbon footprint must not be the only sustainability-related factor for deciding the choice of materials:
Over any product life, maintenance, repairs or early end of life (planned obsolescence) can increase its overall footprint far beyond initial material differences. In addition, loss of service (typically for bridges) may induce large hidden costs, such as queues, wasted fuel, and loss of man-hours.
How much material is used to provide a given service varies with the performance, particularly the strength level, which allows lighter structures and components.
Stainless steel is 100% recyclable. An average stainless steel object is composed of about 60% recycled material of which approximately 40% originates from end-of-life products, while the remaining 60% comes from manufacturing processes. What prevents a higher recycling content is the availability of stainless steel scrap, in spite of a very high recycling rate. According to the International Resource Panel's Metal Stocks in Society report, the per capita stock of stainless steel in use in society is in more developed countries and in less-developed countries. There is a secondary market that recycles usable scrap for many stainless steel markets. The product is mostly coil, sheet, and blanks. This material is purchased at a less-than-prime price and sold to commercial quality stampers and sheet metal houses. The material may have scratches, pits, and dents but is made to the current specifications.
The stainless steel cycle starts with carbon steel scrap, primary metals, and slag. The next step is the production of hot-rolled and cold-finished steel products in steel mills. Some scrap is produced, which is directly reused in the melting shop. The manufacturing of components is the third step. Some scrap is produced and enters the recycling loop. Assembly of final goods and their use does not generate any material loss. The fourth step is the collection of stainless steel for recycling at the end of life of the goods (such as kitchenware, pulp and paper plants, or automotive parts). This is where it is most difficult to get stainless steel to enter the recycling loop, as shown in the table below:
Nanoscale stainless steel
Stainless steel nanoparticles have been produced in the laboratory. These may have applications as additives for high-performance applications. For example, sulfurization, phosphorization, and nitridation treatments to produce nanoscale stainless steel based catalysts could enhance the electrocatalytic performance of stainless steel for water splitting.
Health effects
There is extensive research indicating some probable increased risk of cancer (particularly lung cancer) from inhaling fumes while welding stainless steel. Stainless steel welding is suspected of producing carcinogenic fumes from cadmium oxides, nickel, and chromium. According to Cancer Council Australia, "In 2017, all types of welding fumes were classified as a Group 1 carcinogen."
Stainless steel is generally considered to be biologically inert. However, during cooking, small amounts of nickel and chromium leach out of new stainless steel cookware into highly acidic food. Nickel can contribute to cancer risks—particularly lung cancer and nasal cancer. However, no connection between stainless steel cookware and cancer has been established.
See also
Cobalt-chrome
Corrosion engineering
Corrugated stainless steel tubing
List of blade materials
List of steel producers
Metallic fiber
Pilling–Bedworth ratio
Rouging
Weathering steel
Notes
References
Further reading
International Standard ISO15510:2014
External links
1916 introductions
Biomaterials
Building materials
Chromium alloys
English inventions
Roofing materials | Stainless steel | Physics,Chemistry,Engineering,Biology | 8,229 |
5,411,423 | https://en.wikipedia.org/wiki/Social%20organism | Social organism is a sociological concept, or model, wherein a society or social structure is regarded as a "living organism". Individuals interacting through the various entities comprising a society, such as law, family, crime, etc., are considered as they interact with other entities of the society to meet its needs. Every entity of a society, or social organism, has a function in helping maintain the organism's stability and cohesiveness.
History
The model, or concept, of society-as-organism is traced by Walter M. Simon from Plato ('the organic theory of society'), and by George R. MacLay from Aristotle (384–322 BCE) through 19th-century and later thinkers, including the French philosopher and founder of sociology, Auguste Comte, the Scottish essayist, historian and philosopher Thomas Carlyle, the English philosopher and polymath Herbert Spencer, and the French sociologist Émile Durkheim.
According to Durkheim, the more specialized the function of an organism or society, the greater its development, and vice versa. The three core activities of a society are culture, politics, and economics. Societal health depends on the harmonious interworking of these three activities.
This concept was further developed beginning in 1904, over the next two decades, by the Austrian philosopher and social reformer Rudolf Steiner in his lectures, essays, and books on the Threefold Social Order. The "health" of a social organism can be thought of as a function of the interaction of culture, politics and rights, and economics, which in theory can be studied, modeled, and analyzed.
During his work on social order, Steiner developed his "Fundamental Social Law" of economic systems:
David Sloan Wilson, in his 2002 book, Darwin's Cathedral, applies his multilevel selection theory to social groups and proposes to think of society as an organism. Human groups thus function as single units rather than mere collections of individuals. He claims that organisms and that .
See also
Body politic
Global brain
Noosphere
The Organic Theory of Societies
Superorganism
References
Bibliography
George R. MacLay, The Social Organism: A Short History of the Idea that a Human Society May Be Regarded as a Gigantic Living Creature, North River Press, 1990, .
Henry Rawie, The Social Organism and its Natural Laws, Williams & Wilkins Co., 1990, .
Rudolf Steiner, The Renewal of the Social Organism, Steiner Books, 1985, .
Oliver Luckett, Michel J Casey, The Social Organism: A Radical Understanding of Social Media to Transform Your Business and Life, Hachette Books, 2016, .
External links
Conceivia.com – Creating a new system of society.
Social Psychology and the Social Organism
Superorganisms
Sociological theories | Social organism | Biology | 551 |
27,510,746 | https://en.wikipedia.org/wiki/Tera%20100 | Tera 100 is a supercomputer built by Bull SA for the French Commissariat à l'Énergie Atomique.
On May 26, 2010, Tera 100 was turned on. The computer, which is located in Essonne is able to sustain around 1 petaFLOPs maximum performance and a peak at 1.25 petaFLOPs. It has 4300 Bullx Series S servers ('Mesca'), 140,000 Intel Xeon 7500 processor cores, and 300 TB of memory. The Interconnect is QDR InfiniBand. The file system has a throughput of 500 GB/s and total storage of 20 PB. It uses the SLURM resource manager for scheduling batch jobs.
Tera 100 uses Bull XBAS Linux, a partly Red Hat Enterprise Linux derivative.
In June 2011, TOP500 deemed it the ninth fastest supercomputer in the world, and in 2020, it had dropped off the list.
See also
Computer science
Computing
Tera-10
References
External links
CEA HPC site
Petascale computers
Supercomputing in Europe
X86 supercomputers | Tera 100 | Technology | 238 |
59,457,604 | https://en.wikipedia.org/wiki/Hartmut%20B%C3%A4rnighausen | Hartmut Bärnighausen (born 16 February 1933 in Chemnitz) is a German chemist and crystallographer. He is known for establishing the Bärnighausen trees which describe group-subgroup relationships of crystal structures.
Life
Bärnighausen studied Chemistry at Leipzig University and received his diploma after a diploma thesis with Leopold Wolf in 1955. In May 1958, he flew from East Germany to University of Freiburg, where he worked with Georg Brauer. He finished his doctorate in the group of Georg Brauer in 1959. In 1967, he received his habilitation. From 1967 to 1998, he was a professor for inorganic chemistry at the University of Karlsruhe.
Research
His research focused on the following topics:
crystallographic group theory in crystal chemistry (Bärnighausen trees)
synthesis and characterization of new compounds in including rare earth metals
structure refinements of twinned crystals
Awards
He was awarded the Carl Hermann Medal of the German Crystallographic Society in 1997.
References
Living people
20th-century German chemists
Crystallographers
1933 births
People from Chemnitz
Academic staff of the Karlsruhe Institute of Technology
Leipzig University alumni
University of Freiburg alumni
Inorganic chemists | Hartmut Bärnighausen | Chemistry | 231 |
End of preview. Expand
in Data Studio
README.md exists but content is empty.
- Downloads last month
- 6