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67,459,739 | https://en.wikipedia.org/wiki/Casque%20%28anatomy%29 | A casque is an anatomical feature found in some species of birds, reptiles, and amphibians. In birds, it is an enlargement of the bones of the upper mandible or the skull, either on the front of the face, the top of the head, or both. The casque has been hypothesized to serve as a visual cue to a bird's sex, state of maturity, or social status; as reinforcement to the beak's structure; or as a resonance chamber, enhancing calls. In addition, they may be used in combat with other members of the same species, in the gathering of food, or in thermoregulation.
Birds
Structure
Casques are found in a number of species, including most hornbills, all cassowaries, the maleo, the horned guan, the helmeted guineafowl and several species of curassow. In most of these species, the casque is a bony extension of the or skull that is covered with a cornified layer of skin. However, in cassowaries, a foamy, elastic layer of collagen sits between the bone and the skin. Hornbill casques grow from an area of vascularized tissue at the front of the skull. In most species, the casque is primarily hollow, with a network of bony filaments at the posterior end. The structure starts small in youngsters and develops over time, and at maturity is typically larger in males than in females. For larger species with larger casques, the growth process may take as long as six years. In general, if male and female casques of a species are similarly sized, then they tend to be differently colored, and if they are similarly colored, they tend to be differently sized. Hornbill species that live in dry, open areas tend to have smaller casques than those that live in forested areas.
Functions
Casques may serve different functions in different species, and may serve multiple functions in a single species. In the hornbills, the casques of males and females of each species differ in size, shape, structure, and color, and the casques of young birds are different than those of adults. These various differences may aid in the recognition of potential mates or competitors. Casques on the bill, particularly those that run the length, or nearly the length, of the , may help to strengthen a long, curved beak, which can allow a stronger bite force at the bill's tip.
Some species use their casques for fighting with other members of the same species. Male helmeted hornbills, for example, clash their casques together in mid-air combats that can last up to two hours. Male great hornbills also bash their casques together, sometimes in aerial combat, sometimes while one of the two birds is perched. Indian grey hornbills casque-butt both in aerial battles, and in clashes between perched and flying birds. While most instances involve two males, clashes can also occur between members of a mated pair.
Heat exchange is a primary function of cassowary casques. Studies have shown that the casques efficiently shed heat at high temperatures and help to restrict heat loss at lower temperatures. Cassowaries have been seen dunking their casques into water when temperatures were high. Some theories that have been advanced in the past for cassowary casques – that they provide a "helmet" to protect the birds' heads as they move through the forest, that they serve as a "shovel" during foraging, or that they are used during fights with conspecifics – have now been largely discounted due to a lack of field observations confirming those uses.
Problems and threats
Casques are regularly subject to injury and disease. Injury can be either self-induced, or caused by conspecifics or environmental factors. Invasive squamous cell carcinoma is a common issue, particularly in the great hornbill. Rhinoceros hornbills and helmeted hornbills have long been hunted for their casques, which are used for carvings. Items made from hornbill ivory date back more than 2000 years in Borneo and more than 1000 years in China. Helmeted hornbills are particularly sought, as their casques are densely solid. Although they are protected by law throughout their range, they are killed at unsustainable rates; between 2011 and 2014, for example, more than 1100 skulls were seized from poachers in Indonesia's Kalimantan region alone.
Reptiles
A number of chameleon species have casques, which in these reptiles are bony protrusions on the top of the head. In species which have casques, males tend to have significantly larger casques than females. Studies have shown that casques are used for communication, including the indication of fighting ability. In some species, the size of the casque accurately predicts the bite strength of the individual. The casques form an attachment point for musculature; bigger casques have a larger area for muscle attachment, which can result in a stronger bite. The veiled chameleon of the arid stretches of southern Saudi Arabia and Yemen has a particularly large casque, which scientists have theorised may be used to collect moisture or store fat.
Casqueheaded lizards in the family Corytophanidae have expanded parietal bones. In the genera Corytophanes and Laemanctus, these modifications are present in both sexes; the thickened bones allow for greater bite strength as there is more area for muscle attachment. This may allow these species to utilize larger prey with more chitinous exoskeletons. In species of the genus Basiliscus, on the other hand, males have much larger parietal crests than females. However, the underlying bones are thin and elongated. Their enlarged crests are used in display; large crests can make the animal appear bigger. Females preferentially choose larger males, and larger males are more successful in aggressive encounters with other males.
See also
Comb (anatomy)
Crest (feathers)
Frontal shield
Neck frill
Snood (anatomy)
Wattle (anatomy)
References
Citations
Sources
Bird anatomy
Parts of a bird beak | Casque (anatomy) | [
"Technology"
] | 1,267 | [
"Components",
"Parts of a bird beak"
] |
67,461,503 | https://en.wikipedia.org/wiki/Hydrogel%20fiber | Hydrogel fiber is a hydrogel made into a fibrous state, where its width is significantly smaller than its length. The hydrogel's specific surface area at fibrous form is larger than that of the bulk hydrogel, and its mechanical properties also changed accordingly. As a result of these changes, hydrogel fiber has a faster matter exchange rate and can be woven into different structures.
As a water swollen network with usually low toxicity, hydrogel fiber can be used in a variety of biomedical applications such as drug carrier, optical sensor, and actuator.
But the production of hydrogel fiber can be challenging as the hydrogel is crosslinked and can not be shaped into a fibrous state after polymerization. To make hydrogel into a fibrous state, the pregel solution must be made into fibrous form and then crosslinked while maintaining this shape.
Production method
To produce hydrogel fiber, the solidification of the pregel solution is the most important step. The pregel solution needs to be solidified while maintaining its fibrous shape. To achieve this, several methods based on chemical crosslinking, phase change, rheological property change have been developed.
Physical solidification based
Change in physical interactions can be utilized for the solidification process, and the fibrous state is usually achieved outside of the extrusion nozzle. Due to the reversibility of those physical interactions, subsequent crosslinking is traditionally required.
Electrospinning
Hydrogel fiber can be produced by electrospinning with solidification done by the evaporation of the solvent. The fibrous state is created by the combination of electrostatic repulsion and the surface tension of the solution. But subsequent crosslinking is usually needed to form a crosslinked network. One advantage of electrospun hydrogel fiber is that it has a diameter in range in the order between nm to μm, which is desirable for fast matter exchange. However, utilization of single fiber can be hard to achieve due to the weak mechanical strength of the microscopic fiber and its entanglements after production.
An example of this method would be the production of polyacrylamide (PAAM) semi-interpretation network developed by Tahchi et al. Where the first linear PAAM (provide solidification) was mixed with AAM monomer (form subsequent network) and crosslinker N,N′-methylenebisacrylamide (MBA). During the electrospinning process, the linear PAAM provided the required physical properties to achieve electrospinning, while the AAM monomer and MBA crosslinker were used to form a second crosslinked network inside the PAAM fiber. Although no crosslinking was formed between the first and second networks, the physical entanglement will prevent linear PAAM from leaking.
Drawspinning
Through supramolecular chemistry, pregel solution can solidify through reversible supramolecular interactions such as host-guest interactions. Such interaction can be manipulated through the mechanical force or the temperature. When energy exerted to the network is high enough, physical crosslinking point will break and the polymer will be at liquid state, after leaving the nozzle, the crosslinking can be rapidly formed to solidify the solution.
A case would be the Host–Guest Chemistry reported by Scherman et al. Where the formation of inclusion complex between Cucurbit[8]uril and 1-benzyl-3-vinylimidazolium bromide (BVIm) formed physical crosslinking point for the network. The formation of this physical crosslinking point is controlled by the temperature of the solution. By heating up the solution and cooling it down rapidly at extrusion nuzzle, the hydogel fiber is formed. Also, subsequent crosslinking is performed to form a perment network.
Meltspinning
Some hydrophilic polymer can be made into hydrogel fiber via melt-spinning method, where the solidification is done by the phase transition from the molten state. Similar to the electro-spinning, the pregel solution was kept liquid in the container. After leaving the nuzzle at filament state, the fiber solidified after the encounter of cool ambient air and maintained their shape.
An example would be the meltspinning apparatus built by Long et al., where meltspinning of polylactic acid (PLA) and polycaprolactone (PCL) fiber are achieved.
Direct ink writing
Similar to the draw spinning technique the direct ink writing technique utilized reversible physical solidification to produce hydrogel fibers. The pregel solution was liqufied through shear thinning process which can be generated by adding microscopic particles such as mircrogel. After leaving the nuzzle, the hydrogel will solidify and retain their shape, and network will be made perment after crosslinking.
An example would be the production of the fiber developed by Lewis et al. Where Silk fibroin was used to generate the desired shear-thinning properties. And the network was formed when the solvent was subsequently changed.
Chemical crosslink based
Similar to physical solidification, some chemical crosslinking methods have been developed to produce hydrogel fibers. And the key for the achievement of hydrogel production through the chemical crosslinking method is the effective separation between the formed network and the tube wall.
Microfluid spinning
Many microfluid device-based methods have been developed to produce hydrogel fibers.
Crosslinking of alginate
One of the most commonly used fiber production methods is the crosslinking of sodium alginate by CaCl2, where the formed calcium alginate will act as the crosslinking point to link the alginate chains together to form the network and solidified the polymer. Afterward, this alginate hydrogel fiber can be used as a template for the polymerization of secondary networks. Additionally, by controlling the fluid dynamics inside the microfluid device, the diameter and the shape of the resulting fiber can be tuned without doing modification to the devices.
A practice would be the production of alginate solution reported by Yang et al. They used the sodium alginate as core fluid and CaCl2 as shealth fluid, the crosslinked network (hydrogel fiber) formed once this two fluid met, the laminar flow kept its tubular shape during the reaction.
Photoinitiated crosslinking
Other photoinitiated free radical polymerization reactions can also be used for fiber production. In this case, the shealth fluid was only used to separate the core fluid from the tube wall. Also, to achieve the solidification rapid enough, a more concentrated monomer solution was usually used.
An example would be the production of 4-hydroxybutyl acrylate fiber reported by Beebe et al. The microfluid device they used was built with ethylvinyl acetate caplliary and PDMS rubber. The core fluid was a mixture of 4-hydroxybutyl acrylate, acrylic acid, ethyleneglycol dimethacrylate (crosslinker), 2,2′-dimethoxy-2-phenyl-acetonephenone (photoinitiator). The sheath fluid was only for separation. The crosslinked network was formed by free radical polymerization when the UV light met the core fluid.
Polymerization in tubular molds
Although only being able to produce short hydrogel fibers, production of hydrogel fiber by polymerizing the hydrogel network inside a tubular mold and push out the fiber forcefully can also be achieved. But the friction will increase with the increasing length, and only short hydrogel fibers are feasible.
A case would be the production of poly(acrylamide-co-poly(ethylene glycol) diacrylate) fiber reported by yun et al. The pregel solution was a mixture of AAM, poly(ethylene glycol) diacrylate (PEGDA, crosslinker), and 2-hydroxy-2-methylpropiophenone (photoinitiator). The mixture was injected into a tubular mold and extracted through hydrostatic force afterwards.
Self-lubricate spinning
An interesting phenomenon called self-lubricate spinning can facilitate the demolding of the fiber and enables the continuous production of hydrogel fiber from tubular mold. During the polymerization process, if an inert second polymer is present, it will be particularly expelled from the formed network and being able to move with relative ease. The linear polymer on the surface of the crosslinked network also contains water solvent due to the osmic pressure, thus, a lubrication layer is formed. Therefore, the solidified polymer fiber can exit the tube with decreased friction force and continuous production can be achieved.
An example would be the production the PAAM/PAMPS semi-interpenetration network hydrogel fiber reported by Zhao et al. The pregel solution was the mixture of PAMPS, AAM, PEGDA (crosslinker), and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone (photoinitiator). The pregel solution was fed into a PTFE tube at a constant speed, with UV light being used to initiate the reaction.
Characterization methods
Surface morphology
The surface morphology and shape of the cross-section can be observed via scanning electron microscope (SEM) imaging after removal of solvent. Also, environmental scanning electron microscope (ESEM) can be used to observe wet hydrogel fibers. But different treatments will affect the surface morphology of the hydrogel fiber drastically. If the hydrogel fiber was dried directly, a smooth surface would be obtained because of the collapse of the polymer network after the removal of the solvent. If the hydrogel fiber was lyophilized, a porous surface will usually be found due to the pore-forming effect of the ice crystal. ESEM can directly observe the surface morphology. The resulting image usually indicates a smooth surface with some wrinkled formed due to the gradual loss of water.
Mechanical properties
The mechanical properties of the fibers are tested, but the process can be tricky due to practical reasons. The mechanical properties are tested with Universal Test Machine by fixing the hydrogel fibers between two holders. However, due to the compress of the holder, hydrogel fiber might have a trend to break at the holding point. Also, the loss of water during the test will impact the resulting data, and precaution needs to be taken to meditate the loss. And the tensile strength of the hydrogel fiber is usually smaller than 1 MPa.
Optical properties
Optical properties are tested for optical sensing-related applications. This can include light attenuation, refractive index, transmission, etc. These optical properties are significantly influenced by the composition of the hydrogel.
Biocompatibility
Cell toxicity tests are performed for applications such as cell growth scaffolds. By growing the cell with the ability to produce fluorescent protein, the growth of the cell can be monitored with fluorescent imaging techniques.
Applications
Optical fiber sensors
Transparent hydrogel fibers can be used as optical fiber, and stimuli-responsive functional groups can be grafted on to create optical sensors. For example, in the research done by Yun et al. the glucose-sensitive phenylboronic acid was grafted onto the polymer network. When the glucose concentration changes, the adsorption of the phenylboronic acid will change accordingly and can be recorded with the light intensity at a certain wavelength.
Additive manufacture
Although suffering from poor mechanical strength, some approach has been made to construct hydrogel fiber with textile methods. Also, the electrospun, meltspun, DIW method can produce hydrogel fiber structures at higher dimensions directly.
Biomedical scaffolds
Hydrogel fiber can be used to fabricate scaffolds for cell growth and drug release.
Actuators
Stimuli-responsive hydrogel fibers can be used as actuators and soft robots. By braiding the hydrogel fiber together, the force of the single fiber can be magnified. Also, due to the slipping between hydrogel fibers, the stain of the bending can be reduced to further enhance the performance.
References
Colloidal chemistry
Polymer chemistry | Hydrogel fiber | [
"Chemistry",
"Materials_science",
"Engineering"
] | 2,530 | [
"Colloidal chemistry",
"Materials science",
"Surface science",
"Colloids",
"Polymer chemistry"
] |
67,463,456 | https://en.wikipedia.org/wiki/Presepsin | Presepsin (soluble CD14 subtype, sCD14-ST) is a 13-kDa-cleavage product of CD14 receptor.
Function
Presepsin is a soluble PRR. Presepsin in the circulation is an indicator of monocyte-macrophage activation in response to pathogens.
Clinical relevance
Several clinical studies have demonstrated that presepsin is a specific and sensitive marker for the diagnosis, severity assessment and outcome prediction of sepsis. In addition, presepsin can be used for diagnosing infections in patients with a chronic inflammatory condition, such as liver cirrhosis.
References
Blood proteins
Biomarkers | Presepsin | [
"Biology"
] | 136 | [
"Biomarkers"
] |
67,463,521 | https://en.wikipedia.org/wiki/Ivanti%20Pulse%20Connect%20Secure%20data%20breach | On April 20, 2021, it was reported that suspected Chinese-state backed hacker groups had breached multiple government agencies, defense companies and financial institutions in both the US and Europe after the hackers created and used a Zero-day exploit for Ivanti Pulse Connect Secure VPN devices. A Cybersecurity and Infrastructure Security Agency alert reported that the attacks using the exploited started in June 2020 or earlier. The attacks were believed to be the third major data breach against the U.S. in the previous year behind the 2020 United States federal government data breach and the 2021 Microsoft Exchange Server data breach.
Impact
A Cybersecurity and Infrastructure Security Agency alert reported that the attacks affected "U.S. government agencies, critical infrastructure entities, and other private sector organizations." A spokesperson for Ivanti said that only a "limited number" of customers had been compromised. Mandiant's chief financial officer Charles Carmakal said that while the hack had only a small indication of having a large number of victims. He said the breach was significant because it had allowed unauthorized access to federal and corporate systems for months.
Responses
A spokesperson for Ivanti said that while mitigations are in place a patch to fix the vulnerabilities was not expected until May. With the patch finally being released on May 3, 2021. The CISA issued an emergency directive requiring that federal agencies install product updates. China has denied being behind the attack and accused the U.S. of being the "biggest empire of hacking and tapping."
See also
Cyberwarfare by China
2020 United States federal government data breach
2021 Microsoft Exchange Server data breach
References
2021 in computing
Internet security
Computer security exploits
Cyberattacks
Data breaches
Hacking in the 2020s | Ivanti Pulse Connect Secure data breach | [
"Technology"
] | 349 | [
"Computer security exploits"
] |
67,464,025 | https://en.wikipedia.org/wiki/2-Iodomelatonin | 2-Iodomelatonin is a melatonin analog used as a radiolabelled ligand for the melatonin receptors, MT1, MT2, and MT3. It acts as a full agonist at both MT1 and MT2 receptors.
References
Tryptamines
Melatonin receptor agonists
Acetamides
Iodoarenes
Methoxy compounds | 2-Iodomelatonin | [
"Chemistry"
] | 78 | [
"Melatonin receptor agonists",
"Drug discovery"
] |
67,464,926 | https://en.wikipedia.org/wiki/Ditylum | Ditylum is a genus of diatoms belonging to the family Lithodesmiaceae.
The genus has cosmopolitan distribution.
Species:
Ditylum brightwellii
Ditylum buchananii
Ditylum cornutum
Ditylum ehrenbergii
Ditylum grovei
Ditylum inaequale
Ditylum pernodi
Ditylum segmentale
Ditylum sol
Ditylum trigonum
Ditylum trigonum
References
Diatoms
Diatom genera | Ditylum | [
"Biology"
] | 100 | [
"Diatoms",
"Algae"
] |
67,465,021 | https://en.wikipedia.org/wiki/Doassansia | Doassansia is a genus of fungi belonging to the family Doassansiaceae.
The species of this genus are found in Europe and Northern America.
Ecology
They are parasitic on plants, attaching to leaves and stems of monocotyledons.
Doassansia sagittariae and Doassansiopsis deformans can be found on plants of Sagittaria lancifolia, Doassansia alismatis can be found on various species of Alisma and both Doassansiopsis occulta and Doassansiopsis hydrophila can be found on various species of Potamogeton plants.
Species
As accepted by GBIF;
Doassansia alismatis
Doassansia alpina
Doassansia borealis
Doassansia disticha
Doassansia domingensis
Doassansia eichhorniae
Doassansia epilobii
Doassansia epilobii
Doassansia gossypii
Doassansia hemigraphidis
Doassansia lilaeae
Doassansia limosellae
Doassansia nearctica
Doassansia niesslii
Doassansia opaca
Doassansia peplidis
Doassansia reukaufii
Doassansia rhinanthi
Doassansia sagittariae
Doassansia sintenisii
Doassansia sparganii
Doassansia utriculariae
Doassansia zizaniae
References
Ustilaginomycotina
Basidiomycota genera | Doassansia | [
"Biology"
] | 320 | [
"Fungus stubs",
"Fungi"
] |
67,465,344 | https://en.wikipedia.org/wiki/Wombo | Wombo (stylized as WOMBO) is a Canadian tech startup centered around AI. Their flagship product is an app titled Dream, released in 2021, that has features such as using a provided selfie to create a deepfake of a person, text to image generation, and more.
WOMBO Dream
Dream is an image and video generation app powered by Stable Diffusion. It can be used to create images from text using a variety of style presets. It can also generate a deepfake using 5-10 images of source material.
The app includes a premium tier, which gives users priority processing time and no in-app ads.
Wombo processes images in the cloud. CEO Ben-Zion Benkhin says that all user data is deleted after 24 hours.
Development
Dream was developed in Canada and launched in February 2021 after a beta period in January. Wombo CEO Ben-Zion Benkhin says he got the idea for the app in August 2020. The app is available on both the App Store and Google Play Store.
Reception
Within its first three weeks of release, the app was downloaded over 20 million times, and over 100 million clips were created using the app. The sudden boom in deepfake technology has been described as "a cultural tipping point we aren't ready for", as it is now possible to create a deepfake from any picture off social media in a very short amount of time.
References
External links
Android (operating system) software
Internet properties established in 2021
Photo software
Social media
Deep learning software applications
Deepfakes
Internet memes
Internet memes introduced in 2021It shut down on May 3rd, 2023. | Wombo | [
"Technology"
] | 333 | [
"Computing and society",
"Social media"
] |
67,465,359 | https://en.wikipedia.org/wiki/Biological%20tests%20of%20necessity%20and%20sufficiency | Biological tests of necessity and sufficiency refer to experimental methods and techniques that seek to test or provide evidence for specific kinds of causal relationships in biological systems. A necessary cause is one without which it would be impossible for an effect to occur, while a sufficient cause is one whose presence guarantees the occurrence of an effect. These concepts are largely based on but distinct from ideas of necessity and sufficiency in logic.
Tests of necessity, among which are methods of lesioning or gene knockout, and tests of sufficiency, among which are methods of isolation or discrete stimulation of factors, have become important in current-day experimental designs, and application of these tests have led to a number of notable discoveries and findings in the biological sciences.
Definitions
In biological research, experiments or tests are often used to study predicted causal relationships between two phenomena. These causal relationships may be described in terms of the logical concepts of necessity and sufficiency.
Consider the statement that a phenomenon x causes a phenomenon y. X would be a necessary cause of y when the occurrence of y implies that x needed to have occurred. However, only the occurrence of the necessary condition x may not always result in y also occurring. In other words, when some factor is necessary to cause an effect, it is impossible to have the effect without the cause. X would instead be a sufficient cause of y when the occurrence of x implies that y must then occur. in other words, when some factor is sufficient to cause an effect, the presence of the cause guarantees the occurrence of the effect. However, a different cause z may also cause y, meaning that y may occur without x occurring. For a concrete example, consider the conditional statement "if an object is a square, then it has four sides". It is a necessary condition that an object has four sides if it is true that it is a square; conversely, the object being a square is a sufficient condition for it to be true that an object has four sides.
Four distinct combinations of necessity and sufficiency are possible for a relationship of two conditions. A first condition may be:
necessary but not sufficient
sufficient but not necessary
both necessary and sufficient
neither necessary nor sufficient
for a second condition to be true.
Laypersons or novice scientists may prefer to think of these concepts of necessity and sufficiency in certain ways. In a study of undergraduate psychology students, more students viewed necessity in negative terms of "if no x, then no y" rather than the logically equivalent "if y, then x" than they did for sufficiency; most of them understood sufficiency as "if x, then y" rather than the logically equivalent "if no y, then no x". This result also suggested the students were more likely to prefer thinking about causes in the forward (x to y) direction rather than the backward (y to x) direction.
Misunderstandings may occur regarding the kinds of evidence that can support these causal relationships; a study applying the causal concepts of necessity and sufficiency found that college students in a biochemistry class were likely to erroneously misinterpret correlations as signifying sufficiency to cause an effect. The study on undergraduate psychology students also indicated a potential discrepancy in understanding sufficiency, where it was found that some students understood a cause as being sufficient for an effect even when the effect did not always follow the cause; while in the reverse direction, an effect may have alternative causes, but a cause can only be sufficient if it always results in the effect occurring.
Tests of necessity
Necessity can only be proven by demonstrating that a system does not work when the piece in question is not active, meaning that it is required for functioning. Biological research uses a variety of techniques to inhibit a structure or genetic player, such as lesions and knockout/deletion. All of these techniques fall into the category of loss of function.
Lesioning
Lesioning is a test of necessity involves physically damaging a structure so that it loses its function. If lesioning a structure causes a change in the system, then that structure is necessary. Lesioning can look very different across scientific disciplines.
In psychology, information about necessity may be gleaned by observing changes in behavior when a brain region has been destroyed, either by accident or illness in a human or purposefully in a lab animal. Other disciplines may target specific cell types and tag them for degradation. The GAL4/UAS System "reports" a subset of genes of interest although it has no independent effect on tissue. When combined with an apoptotic gene, such as reaper (rpr), all cells that express the genes of interest along with GAL4/UAS, will initiate cell death, creating a legion specific to a cell type.
A classic example of lesioning in chronobiology is the exploration of circadian navigation in monarch butterflies. In a landmark experiment, Dr. Christine Merlin and Dr. Steven Reppert removed (lesioned) the antennae of monarch butterflies and tested their ability to navigate. They found that the Monarchs could not navigate without their antennae. The investigators’ use of lesioning allowed them to come to the conclusion that Monarch's antennae are necessary for navigation because their absence prevented this system from functioning.
Knockout
A knockout refers to the inactivation of a gene. This can be done several ways, such as altering the DNA sequence so that it no longer performs its function, altering the promoter region so that it is not transcribed, or deleting the gene entirely. Aside from helping scientists understand the function of gene, observing behavior or some other variable before and after deletion can create an argument for its necessity if a behavior or system ceases to function.
Allada et al. performed a knockout of the drosophila gene CLOCK, a gene earlier identified as a circadian gene via forward genetics. In this experiment, they altered the Clock gene to stop it from performing its normal function. Clock knockout flies did not exhibit a twenty-four hour rhythm as was recorded for unchanged flies. This led the researchers to conclude that Clock is necessary for the twenty four hour rhythm of flies.
Tests of sufficiency
Sufficiency can be proven by demonstrating that a system can operate when the element in question is active without the influence of other elements. However, this does not indicate that the element in question is required for functioning. The element allows the system to function, but its presence is not required in order for the system to function.
Tests of sufficiency in biology are used to determine if the presence of an element permits the biological phenomenon to occur. In other words, if sufficient conditions are met, the targeted event is able to take place. However, this does not mean that the absence of a sufficient biological element inhibits the biological event from occurring.
Tests of sufficiency include a gain of function by discrete stimulation and isolation of a biological element to observe a change in the targeted event. These types of methods are imperative to several subfields of biology. Particularly, tests of sufficiency are common in the field of chronobiology.
Discrete stimulation
When performing discrete stimulation, researchers aim to provide stimuli solely to the biological element of interest. Returning to Dr. Reppert and Dr. Merlin's work with monarch butterflies, when inquiring about the role of antennas in the monarch butterfly's sun compass orientation, the researchers only provided light to the antennas of the butterfly. They found that stimulating the antennas alone was enough for the butterflies to entrain comparably to non-stimulated butterflies who were entrained in the same condition. As a result, the flight behavior of the stimulated group was similar to butterflies who were traditionally entrained. As a result, there was evidence that the antennas are sufficient for sun compass orientation.
Discrete stimulation has also been used to investigate the location and quantity of the circadian pacemakers in plants, namely Arabidopsis and the tobacco plant. When investigating the coupling of the circadian systems in the intact plants, Thain et al. placed foil covering over one cotyledon and entrained the other uncovered cotyledon to a light-dark cycle of 12 hours light and 12 hours dark (LD 12:12), 6 hours ahead of the covered cotyledon. Then, the researchers covered the opposite cotyledon and entrained the newly exposed cotyledon to a 12:12 light-dark cycle delayed by 6 hours, creating a 12-hour difference between the cotyledons. Using transgenic bioluminescence, Thain et al. discovered that the two leaves were out of phase with each other, displaying peaks in luminescence at opposite times. This provided evidence for the notion that each cotyledon is sufficient for maintaining an independent circadian rhythm and has its own autonomous circadian oscillator.
Isolation
The method of isolation to determine sufficiency involves a single biological element undergoing experimentation, being secluded from interactions with other relevant biological elements. This method includes the removal of the element in question and placing it into secluded testing conditions.
Reppert and Merlin used the method of isolation in their research in when examining the influence of circadian clock outputs of the antennas on the sun-compass orientation of monarch butterflies in 2009. The researchers separated the antennas from the butterfly and placed them in separate conditions. Then, the researchers proceeded patch clamp onto a cell in the antenna and puff odorant onto the isolated cell to determine if there is rhythmicity in its firing rate. They concluded that it does show rhythmicity in its response to the odorant, with its firing rate being high at night and low in the day. The isolation of the antenna proves its sufficiency because it is the only relevant biological element sustaining the rhythm in the system.
Additionally, they utilizes this approach again in their research in 2012 examining the influence of the temporal relationship between antennas of the monarch butterfly on its sun-compass orientation. The researchers analyzed the importance of the presence of both antennas for sun-compass orientation. They tested this by removing a single antenna from the butterfly and assessing its flight behavior. As a result, they found that one antenna was sufficient for correct sun compass orientation, regardless of its laterality.
The method of isolation is not limited to isolating single cells or organs for experimentation. It can be used to analyze proteins and their role in an organism as well. Namely, Nakajima et al. utilizes this in 2005 while working with Kai proteins such as KaiA, KaiB, KaiC, which regulate circadian gene expression in cyanobacteria. These proteins are major components of the cyanobacteria circadian clock, altering their conformation and phosphorylation state throughout the day. Questioning the transcription-translation feedback loop as a means of explaining the cyanobacterial circadian clock, Nakajima et al. isolated the KaiABC proteins by lysing S. elongatus and placing them in test tubes with ATP. Consequently, in vitro phosphorylation of KaiC oscillated with a period of approximately 24 hours at slightly smaller amplitude than the in vivo oscillation. This demonstrated that the KaiABC proteins are sufficient for maintaining circadian rhythm when provided with ATP. It also presented KaiABC as the circadian post-translation oscillator that regulates the clock in S. elongatus, in tandem with transcription-translation feedback loop (TTFL) model as mechanism for the organism's clock.
Critiques
The use of the concepts of necessity and sufficiency in experimental design and research interpretations has been criticized on the grounds that the way they are used may not always be consistent with the meanings of these concepts in formal logic. In particular, Yoshihara and Yoshihara have criticized the usage of the phrase "necessary and sufficient" to describe biological factors in research. They argue that researchers who use that phrase to describe the importance of one factor for another run the risk of miscommunicating their findings to those who interpret the phrase in a logical sense, but at the same time, citing the example of how command neurons are formally defined, that applying the idea of "necessary and sufficient" to biological factors in a strictly logical sense may be overly restrictive and result in some findings being inappropriately dismissed. As an alternative description, the authors suggest using the phrase "indispensable and inducing".
References
Causal inference
Necessity and sufficiency
Biological techniques and tools | Biological tests of necessity and sufficiency | [
"Biology"
] | 2,528 | [
"nan"
] |
67,465,897 | https://en.wikipedia.org/wiki/Affine%20symmetric%20group | The affine symmetric groups are a family of mathematical structures that describe the symmetries of the number line and the regular triangular tiling of the plane, as well as related higher-dimensional objects. In addition to this geometric description, the affine symmetric groups may be defined in other ways: as collections of permutations (rearrangements) of the integers () that are periodic in a certain sense, or in purely algebraic terms as a group with certain generators and relations. They are studied in combinatorics and representation theory.
A finite symmetric group consists of all permutations of a finite set. Each affine symmetric group is an infinite extension of a finite symmetric group. Many important combinatorial properties of the finite symmetric groups can be extended to the corresponding affine symmetric groups. Permutation statistics such as descents and inversions can be defined in the affine case. As in the finite case, the natural combinatorial definitions for these statistics also have a geometric interpretation.
The affine symmetric groups have close relationships with other mathematical objects, including juggling patterns and certain complex reflection groups. Many of their combinatorial and geometric properties extend to the broader family of affine Coxeter groups.
Definitions
The affine symmetric group may be equivalently defined as an abstract group by generators and relations, or in terms of concrete geometric and combinatorial models.
Algebraic definition
One way of defining groups is by generators and relations. In this type of definition, generators are a subset of group elements that, when combined, produce all other elements. The relations of the definition are a system of equations that determine when two combinations of generators are equal. In this way, the affine symmetric group is generated by a set
of elements that satisfy the following relations: when ,
(the generators are involutions),
if is not one of , indicating that for these pairs of generators, the group operation is commutative, and
.
In the relations above, indices are taken modulo , so that the third relation includes as a particular case . (The second and third relation are sometimes called the braid relations.) When , the affine symmetric group is the infinite dihedral group generated by two elements subject only to the relations .
These relations can be rewritten in the special form that defines the Coxeter groups, so the affine symmetric groups are Coxeter groups, with the as their Coxeter generating sets. Each Coxeter group may be represented by a Coxeter–Dynkin diagram, in which vertices correspond to generators and edges encode the relations between them. For , the Coxeter–Dynkin diagram of is the -cycle (where the edges correspond to the relations between pairs of consecutive generators and the absence of an edge between other pairs of generators indicates that they commute), while for it consists of two nodes joined by an edge labeled .
Geometric definition
In the Euclidean space with coordinates , the set of points for which forms a (hyper)plane, an -dimensional subspace. For every pair of distinct elements and of and every integer , the set of points in that satisfy forms an -dimensional subspace within , and there is a unique reflection of that fixes this subspace. Then the affine symmetric group can be realized geometrically as a collection of maps from to itself, the compositions of these reflections.
Inside , the subset of points with integer coordinates forms the root lattice, . It is the set of all the integer vectors such that . Each reflection preserves this lattice, and so the lattice is preserved by the whole group.
The fixed subspaces of these reflections divide into congruent simplices, called alcoves. The situation when is shown in the figure; in this case, the root lattice is a triangular lattice, the reflecting lines divide into equilateral triangle alcoves, and the roots are the centers of nonoverlapping hexagons made up of six triangular alcoves.
To translate between the geometric and algebraic definitions, one fixes an alcove and consider the hyperplanes that form its boundary. The reflections through these boundary hyperplanes may be identified with the Coxeter generators. In particular, there is a unique alcove (the fundamental alcove) consisting of points such that , which is bounded by the hyperplanes ..., and illustrated in the case . For , one may identify the reflection through with the Coxeter generator , and also identify the reflection through with the generator .
Combinatorial definition
The elements of the affine symmetric group may be realized as a group of periodic permutations of the integers. In particular, say that a function is an affine permutation if
it is a bijection (each integer appears as the value of for exactly one ),
for all integers (the function is equivariant under shifting by ), and
, the th triangular number.
For every affine permutation, and more generally every shift-equivariant bijection, the numbers must all be distinct modulo . An affine permutation is uniquely determined by its window notation , because all other values of can be found by shifting these values. Thus, affine permutations may also be identified with tuples of integers that contain one element from each congruence class modulo and sum to .
To translate between the combinatorial and algebraic definitions, for one may identify the Coxeter generator with the affine permutation that has window notation , and also identify the generator with the affine permutation . More generally, every reflection (that is, a conjugate of one of the Coxeter generators) can be described uniquely as follows: for distinct integers , in and arbitrary integer , it maps to , maps to , and fixes all inputs not congruent to or modulo .
Representation as matrices
Affine permutations can be represented as infinite periodic permutation matrices. If is an affine permutation, the corresponding matrix has entry 1 at position in the infinite grid for each integer , and all other entries are equal to 0. Since is a bijection, the resulting matrix contains exactly one 1 in every row and column. The periodicity condition on the map ensures that the entry at position is equal to the entry at position for every pair of integers . For example, a portion of the matrix for the affine permutation is shown in the figure. In row 1, there is a 1 in column 2; in row 2, there is a 1 in column 0; and in row 3, there is a 1 in column 4. The rest of the entries in those rows and columns are all 0, and all the other entries in the matrix are fixed by the periodicity condition.
Relationship to the finite symmetric group
The affine symmetric group contains the finite symmetric group of permutations on elements as both a subgroup and a quotient group. These connections allow a direct translation between the combinatorial and geometric definitions of the affine symmetric group.
As a subgroup
There is a canonical way to choose a subgroup of that is isomorphic to the finite symmetric group .
In terms of the algebraic definition, this is the subgroup of generated by (excluding the simple reflection ). Geometrically, this corresponds to the subgroup of transformations that fix the origin, while combinatorially it corresponds to the window notations for which (that is, in which the window notation is the one-line notation of a finite permutation).
If is the window notation of an element of this standard copy of , its action on the hyperplane in is given by permutation of coordinates: . (In this article, the geometric action of permutations and affine permutations is on the right; thus, if and are two affine permutations, the action of on a point is given by first applying , then applying .)
There are also many nonstandard copies of contained in . A geometric construction is to pick any point in (that is, an integer vector whose coordinates sum to 0); the subgroup of of isometries that fix is isomorphic to .
As a quotient
There is a simple map (technically, a surjective group homomorphism) from onto the finite symmetric group . In terms of the combinatorial definition, an affine permutation can be mapped to a permutation by reducing the window entries modulo to elements of , leaving the one-line notation of a permutation. In this article, the image of an affine permutation is called the underlying permutation of .
The map sends the Coxeter generator to the permutation whose one-line notation and cycle notation are and , respectively.
The kernel of is by definition the set of affine permutations whose underlying permutation is the identity. The window notations of such affine permutations are of the form , where is an integer vector such that , that is, where . Geometrically, this kernel consists of the translations, the isometries that shift the entire space without rotating or reflecting it. In an abuse of notation, the symbol is used in this article for all three of these sets (integer vectors in , affine permutations with underlying permutation the identity, and translations); in all three settings, the natural group operation turns into an abelian group, generated freely by the vectors .
Connection between the geometric and combinatorial definitions
The affine symmetric group has as a normal subgroup, and is isomorphic to the semidirect product
of this subgroup with the finite symmetric group , where the action of on is by permutation of coordinates. Consequently, every element of has a unique realization as a product
where is a permutation in the standard copy of in and is a translation in .
This point of view allows for a direct translation between the combinatorial and geometric definitions of : if one writes where and then the affine permutation corresponds to the rigid motion of defined by
Furthermore, as with every affine Coxeter group, the affine symmetric group acts transitively and freely on the set of alcoves: for each two alcoves, a unique group element takes one alcove to the other. Hence, making an arbitrary choice of alcove places the group in one-to-one correspondence with the alcoves: the identity element corresponds to , and every other group element corresponds to the alcove that is the image of under the action of .
Example:
Algebraically, is the infinite dihedral group, generated by two generators subject to the relations . Every other element of the group can be written as an alternating product of copies of and .
Combinatorially, the affine permutation has window notation , corresponding to the bijection for every integer . The affine permutation has window notation , corresponding to the bijection for every integer . Other elements have the following window notations:
Geometrically, the space on which acts is a line, with infinitely many equally spaced reflections. It is natural to identify the line with the real line , with reflection around the point , and with reflection around the point . In this case, the reflection reflects across the point for any integer , the composition translates the line by , and the composition translates the line by .
Permutation statistics and permutation patterns
Many permutation statistics and other features of the combinatorics of finite permutations can be extended to the affine case.
Descents, length, and inversions
The length of an element of a Coxeter group is the smallest number such that can be written as a product of Coxeter generators of .
Geometrically, the length of an element in is the number of reflecting hyperplanes that separate and , where is the fundamental alcove (the simplex bounded by the reflecting hyperplanes of the Coxeter generators ).
Combinatorially, the length of an affine permutation is encoded in terms of an appropriate notion of inversions: for an affine permutation , the length is
Alternatively, it is the number of equivalence classes of pairs such that and under the equivalence relation if for some integer .
The generating function for length in is
Similarly, there is an affine analogue of descents in permutations: an affine permutation has a descent in position if . (By periodicity, has a descent in position if and only if it has a descent in position for all integers .)
Algebraically, the descents corresponds to the right descents in the sense of Coxeter groups; that is, is a descent of if and only if . The left descents (that is, those indices such that ) are the descents of the inverse affine permutation ; equivalently, they are the values such that occurs before in the sequence .
Geometrically, is a descent of if and only if the fixed hyperplane of separates the alcoves and
Because there are only finitely many possibilities for the number of descents of an affine permutation, but infinitely many affine permutations, it is not possible to naively form a generating function for affine permutations by number of descents (an affine analogue of Eulerian polynomials). One possible resolution is to consider affine descents (equivalently, cyclic descents) in the finite symmetric group . Another is to consider simultaneously the length and number of descents of an affine permutation. The multivariate generating function for these statistics over simultaneously for all is
where is the number of descents of the affine permutation and is the -exponential function.
Cycle type and reflection length
Any bijection partitions the integers into a (possibly infinite) list of (possibly infinite) cycles: for each integer , the cycle containing is the sequence where exponentiation represents functional composition.
For an affine permutation , the following conditions are equivalent: all cycles of are finite, has finite order, and the geometric action of on the space has at least one fixed point.
The reflection length of an element of is the smallest number such that there exist reflections such that . (In the symmetric group, reflections are transpositions, and the reflection length of a permutation is , where is the number of cycles of .) In , the following formula was proved for the reflection length of an affine permutation : for each cycle of , define the weight to be the integer k such that consecutive entries congruent modulo differ by exactly . Form a tuple of cycle weights of (counting translates of the same cycle by multiples of only once), and define the nullity to be the size of the smallest set partition of this tuple so that each part sums to 0. Then the reflection length of is
where is the underlying permutation of .
For every affine permutation , there is a choice of subgroup of such that , , and for the standard form implied by this semidirect product, the reflection lengths are additive, that is, .
Fully commutative elements and pattern avoidance
A reduced word for an element of a Coxeter group is a tuple of Coxeter generators of minimum possible length such that . The element is called fully commutative if any reduced word can be transformed into any other by sequentially swapping pairs of factors that commute. For example, in the finite symmetric group , the element is fully commutative, since its two reduced words and can be connected by swapping commuting factors, but is not fully commutative because there is no way to reach the reduced word starting from the reduced word by commutations.
proved that in the finite symmetric group , a permutation is fully commutative if and only if it avoids the permutation pattern 321, that is, if and only if its one-line notation contains no three-term decreasing subsequence. In , this result was extended to affine permutations: an affine permutation is fully commutative if and only if there do not exist integers such that .
The number of affine permutations avoiding a single pattern is finite if and only if avoids the pattern 321, so in particular there are infinitely many fully commutative affine permutations. These were enumerated by length in .
Parabolic subgroups and other structures
The parabolic subgroups of and their coset representatives offer a rich combinatorial structure. Other aspects of affine symmetric groups, such as their Bruhat order and representation theory, may also be understood via combinatorial models.
Parabolic subgroups, coset representatives
]
A standard parabolic subgroup of a Coxeter group is a subgroup generated by a subset of its Coxeter generating set. The maximal parabolic subgroups are those that come from omitting a single Coxeter generator. In , all maximal parabolic subgroups are isomorphic to the finite symmetric group . The subgroup generated by the subset consists of those affine permutations that stabilize the interval , that is, that map every element of this interval to another element of the interval.
For a fixed element of , let be the maximal proper subset of Coxeter generators omitting , and let denote the parabolic subgroup generated by . Every coset has a unique element of minimum length. The collection of such representatives, denoted , consists of the following affine permutations:
In the particular case that , so that is the standard copy of inside , the elements of may naturally be represented by abacus diagrams: the integers are arranged in an infinite strip of width , increasing sequentially along rows and then from top to bottom; integers are circled if they lie directly above one of the window entries of the minimal coset representative. For example, the minimal coset representative is represented by the abacus diagram at right. To compute the length of the representative from the abacus diagram, one adds up the number of uncircled numbers that are smaller than the last circled entry in each column. (In the example shown, this gives .)
Other combinatorial models of minimum-length coset representatives for can be given in terms of core partitions (integer partitions in which no hook length is divisible by ) or bounded partitions (integer partitions in which no part is larger than ). Under these correspondences, it can be shown that the weak Bruhat order on is isomorphic to a certain subposet of Young's lattice.
Bruhat order
The Bruhat order on has the following combinatorial realization. If is an affine permutation and and are integers, define
to be the number of integers such that and . (For example, with , one has : the three relevant values are , which are respectively mapped by to 1, 2, and 4.) Then for two affine permutations , , one has that in Bruhat order if and only if for all integers , .
Representation theory and an affine Robinson–Schensted correspondence
In the finite symmetric group, the Robinson–Schensted correspondence gives a bijection between the group and pairs of standard Young tableaux of the same shape. This bijection plays a central role in the combinatorics and the representation theory of the symmetric group. For example, in the language of Kazhdan–Lusztig theory, two permutations lie in the same left cell if and only if their images under Robinson–Schensted have the same tableau , and in the same right cell if and only if their images have the same tableau . In , Jian-Yi Shi showed that left cells for are indexed instead by tabloids, and in he gave an algorithm to compute the tabloid analogous to the tableau for an affine permutation. In , the authors extended Shi's work to give a bijective map between and triples consisting of two tabloids of the same shape and an integer vector whose entries satisfy certain inequalities. Their procedure uses the matrix representation of affine permutations and generalizes the shadow construction, introduced in .
Inverse realizations
In some situations, one may wish to consider the action of the affine symmetric group on or on alcoves that is inverse to the one given above. These alternate realizations are described below.
In the combinatorial action of on , the generator acts by switching the values and . In the inverse action, it instead switches the entries in positions and . Similarly, the action of a general reflection will be to switch the entries at positions and for each , fixing all inputs at positions not congruent to or modulo .
In the geometric action of , the generator acts on an alcove by reflecting it across one of the bounding planes of the fundamental alcove . In the inverse action, it instead reflects across one of its own bounding planes. From this perspective, a reduced word corresponds to an alcove walk on the tessellated space .
Relationship to other mathematical objects
The affine symmetric groups are closely related to a variety of other mathematical objects.
Juggling patterns
In , a correspondence is given between affine permutations and juggling patterns encoded in a version of siteswap notation. Here, a juggling pattern of period is a sequence of nonnegative integers (with certain restrictions) that captures the behavior of balls thrown by a juggler, where the number indicates the length of time the th throw spends in the air (equivalently, the height of the throw). The number of balls in the pattern is the average . The Ehrenborg–Readdy correspondence associates to each juggling pattern of period the function defined by
where indices of the sequence a are taken modulo . Then is an affine permutation in , and moreover every affine permutation arises from a juggling pattern in this way. Under this bijection, the length of the affine permutation is encoded by a natural statistic in the juggling pattern:
where is the number of crossings (up to periodicity) in the arc diagram of a. This allows an elementary proof of the generating function for affine permutations by length.
For example, the juggling pattern 441 has and . Therefore, it corresponds to the affine permutation . The juggling pattern has four crossings, and the affine permutation has length .
Similar techniques can be used to derive the generating function for minimal coset representatives of by length.
Complex reflection groups
In a finite-dimensional real inner product space, a reflection is a linear transformation that fixes a linear hyperplane pointwise and negates the vector orthogonal to the plane. This notion may be extended to vector spaces over other fields. In particular, in a complex inner product space, a reflection is a unitary transformation of finite order that fixes a hyperplane. This implies that the vectors orthogonal to the hyperplane are eigenvectors of , and the associated eigenvalue is a complex root of unity. A complex reflection group is a finite group of linear transformations on a complex vector space generated by reflections.
The complex reflection groups were fully classified by : each complex reflection group is isomorphic to a product of irreducible complex reflection groups, and every irreducible either belongs to an infinite family (where , , and are positive integers such that divides ) or is one of 34 other (so-called "exceptional") examples. The group is the generalized symmetric group: algebraically, it is the wreath product of the cyclic group with the symmetric group . Concretely, the elements of the group may be represented by monomial matrices (matrices having one nonzero entry in every row and column) whose nonzero entries are all th roots of unity. The groups are subgroups of , and in particular the group consists of those matrices in which the product of the nonzero entries is equal to 1.
In , Shi showed that the affine symmetric group is a generic cover of the family , in the following sense: for every positive integer , there is a surjection from to , and these maps are compatible with the natural surjections when that come from raising each entry to the th power. Moreover, these projections respect the reflection group structure, in that the image of every reflection in under is a reflection in ; and similarly when the image of the standard Coxeter element in is a Coxeter element in .
Affine Lie algebras
Each affine Coxeter group is associated to an affine Lie algebra, a certain infinite-dimensional non-associative algebra with unusually nice representation-theoretic properties. In this association, the Coxeter group arises as a group of symmetries of the root space of the Lie algebra (the dual of the Cartan subalgebra). In the classification of affine Lie algebras, the one associated to is of (untwisted) type , with Cartan matrix for and
(a circulant matrix) for .
Like other Kac–Moody algebras, affine Lie algebras satisfy the Weyl–Kac character formula, which expresses the characters of the algebra in terms of their highest weights. In the case of affine Lie algebras, the resulting identities are equivalent to the Macdonald identities. In particular, for the affine Lie algebra of type , associated to the affine symmetric group , the corresponding Macdonald identity is equivalent to the Jacobi triple product.
Braid group and group-theoretic properties
Coxeter groups have a number of special properties not shared by all groups. These include that their word problem is decidable (that is, there exists an algorithm that can determine whether or not any given product of the generators is equal to the identity element) and that they are linear groups (that is, they can be represented by a group of invertible matrices over a field).
Each Coxeter group is associated to an Artin–Tits group , which is defined by a similar presentation that omits relations of the form for each generator . In particular, the Artin–Tits group associated to is generated by elements subject to the relations for (and no others), where as before the indices are taken modulo (so ). Artin–Tits groups of Coxeter groups are conjectured to have many nice properties: for example, they are conjectured to be torsion-free, to have trivial center, to have solvable word problem, and to satisfy the conjecture. These conjectures are not known to hold for all Artin–Tits groups, but in it was shown that has these properties. (Subsequently, they have been proved for the Artin–Tits groups associated to affine Coxeter groups.) In the case of the affine symmetric group, these proofs make use of an associated Garside structure on the Artin–Tits group.
Artin–Tits groups are sometimes also known as generalized braid groups, because the Artin–Tits group of the (finite) symmetric group is the braid group on strands. Not all Artin–Tits groups have a natural representation in terms of geometric braids. However, the Artin–Tits group of the hyperoctahedral group (geometrically, the symmetry group of the n-dimensional hypercube; combinatorially, the group of signed permutations of size n) does have such a representation: it is given by the subgroup of the braid group on strands consisting of those braids for which a particular strand ends in the same position it started in, or equivalently as the braid group of strands in an annular region. Moreover, the Artin–Tits group of the hyperoctahedral group can be written as a semidirect product of with an infinite cyclic group. It follows that may be interpreted as a certain subgroup consisting of geometric braids, and also that it is a linear group.
Extended affine symmetric group
The affine symmetric group is a subgroup of the extended affine symmetric group. The extended group is isomorphic to the wreath product . Its elements are extended affine permutations: bijections such that for all integers . Unlike the affine symmetric group, the extended affine symmetric group is not a Coxeter group. But it has a natural generating set that extends the Coxeter generating set for : the shift operator whose window notation is generates the extended group with the simple reflections, subject to the additional relations .
Combinatorics of other affine Coxeter groups
The geometric action of the affine symmetric group places it naturally in the family of affine Coxeter groups, each of which has a similar geometric action on an affine space. The combinatorial description of the may also be extended to many of these groups: in , an axiomatic description is given of certain permutation groups acting on (the "George groups", in honor of George Lusztig), and it is shown that they are exactly the "classical" Coxeter groups of finite and affine types A, B, C, and D. (In the classification of affine Coxeter groups, the affine symmetric group is type A.) Thus, the combinatorial interpretations of descents, inversions, etc., carry over in these cases. Abacus models of minimum-length coset representatives for parabolic quotients have also been extended to this context.
History
The study of Coxeter groups in general could be said to first arise in the classification of regular polyhedra (the Platonic solids) in ancient Greece. The modern systematic study (connecting the algebraic and geometric definitions of finite and affine Coxeter groups) began in work of Coxeter in the 1930s. The combinatorial description of the affine symmetric group first appears in work of , and was expanded upon by ; both authors used the combinatorial description to study the Kazhdan–Lusztig cells of . The proof that the combinatorial definition agrees with the algebraic definition was given by .
References
Notes
Works cited
Coxeter groups
Reflection groups
Permutation groups
Symmetry
Representation theory | Affine symmetric group | [
"Physics",
"Mathematics"
] | 6,132 | [
"Euclidean symmetries",
"Reflection groups",
"Fields of abstract algebra",
"Geometry",
"Representation theory",
"Symmetry"
] |
67,466,517 | https://en.wikipedia.org/wiki/Familial%20sleep%20traits | Familial sleep traits are heritable variations in sleep patterns, resulting in abnormal sleep-wake times and/or abnormal sleep length.
Circadian rhythms are coordinated physiological and biological changes that oscillate on an approximately 24-hour cycle. Disruptions to these rhythms in humans may affect the duration, onset, and/or quality of sleep during this cycle, resulting in familial sleep traits. These traits are not necessarily syndromes because they do not always cause distress among individuals. Instead of being disorders, familial sleep traits are variations in an individual's biological tendencies of sleep-wake times, and are only considered syndromes if affected individuals complain about life interference, in which case they may fall under the category of Circadian Rhythm Sleep Disorders (CRSD) that affect sleep timing and circadian rhythms. Some of these circadian disorders include Advanced Sleep Phase Disorder (ASPD) and Delayed Sleep Phase Disorder (DSPD). Familial sleep traits are more specific than CRSD because they are heritable and involve a wide range of Mendelian genes. Evidence has shown that genes significantly influence sleep schedules in mammals, including humans, and account for one-third of the variation in sleep quality and duration. Studies in human monozygotic twins have provided evidence that genetic factors affect "normal" sleep patterns as well, meaning ones where no individual has been diagnosed with an altered phenotypic sleep trait.
Sleep timing is controlled by the circadian clock, which can entrain to environmental stimuli (usually a light-dark cycle) and is regulated by a transcription-translation feedback loop (TTFL). In humans, there are multiple genes involved in this molecular biological clock, which when mutated may result in sleep disorders such as Familial Advanced Sleep Phase (FASP), Familial Delayed Sleep Phase (FDSP), and Familial Natural Short Sleep (FNSS). Some mutations in Mendelian genes that are involved in the TTFL have been identified as the causes of these sleep traits, including PER2, PER3, CRY2, CRY1. Other Mendelian genes that are not known to play a core role in the TTFL but are involved in FNSS include DEC2 and ADRB1.
With some familial sleep traits, there may be a shift in an individual's chronotype, which describes the time of sleep-wake behaviors that result from circadian rhythms. Chronotype may shift depending on multiple factors including gender and age. Individuals with FASP have earlier chronotypes and individuals with FDSP have later chronotypes compared to a conventional sleep period which runs from approximately 10pm to 7am. Individuals may meet the criteria for FASP or FDSP if they have Advanced Sleep Phase or Delayed Sleep Phase and at least one first degree relative with the trait. Researchers have examined the human prevalence of FASP to be 0.33-0.5% by including individuals who have a sleep onset at approximately 8:30pm and offset at 5:30am. FDSP, which includes individuals who have a delayed sleep onset and offset, has an unknown human prevalence and may vary based on location, definition, and age.
History of discoveries
Familial sleep traits have been difficult to study due to the various environmental influences (such as entraining daily alarms, artificial light at night, and caffeine or stimulant intake) that can contribute to different behavioral phenotypes in humans. Despite these potential difficulties, Louis Ptáček and colleagues discovered evidence of a human familial circadian rhythm variant in the 1990s. This variant resulted in a shorter period and an advance of melatonin and temperature rhythms and was initially termed Advanced Sleep Phase Syndrome (ASPS) in a 1999 publication. Individuals with ASPS have earlier sleep and wake onsets, meaning they both go to bed and wake up earlier compared to control groups. The first participant with this phenotype told researchers she recognized similar sleep patterns in her family. From structured interviews and family pedigree analysis, some of these individuals were identified to have ASPS as well, providing evidence that this phenotype could be genetic, resulting in Familial Advanced Sleep Phase (FASP). In this 1999 publication, researchers were also able to conclude that this trait has an autosomal dominant mode of inheritance with high penetrance. This means that the genes involved in FASP are passed through non-sex chromosomes, and an individual only needs one copy of the gene across homologs for the gene to be expressed. Since this initial 1999 FASP publication, other circadian biologists including Phyllis Zee and Joseph Takahashi have conducted further genetic analysis. They published a paper in 2001 that presented data showing a phenotypically characterized case of Advanced Sleep Phase Syndrome to provide further evidence that this trait can be hereditary. Since these studies, Csnk1d, PER2, PER3, and CRY2 have all been identified as important in hereditary FASP.
Another sleep trait, Delayed Sleep Phase Syndrome (DSPS) was first identified by Elliot Weitzman and colleagues in 1981. Individuals with DSPS typically cannot fall asleep until later and wake up later compared to control groups. They often cannot fall asleep until between 2:00-6:00am, but then have a normal sleep duration. However, DSPS was not hypothesized to have a genetic component until researchers at University of California, San Diego discovered a familial pedigree with DSPS in 2001, adding this Familial Delayed Sleep Phase (FDSP) to the list of heritable sleep traits. Almost two decades later in 2017, Michael Young and colleagues in New York published findings that further supported delayed sleep to have a genetic component, resulting in FDSP. These scientists reported that a mutation in CRY1, a component of the TTFL that represses Clock and Bmal1, results in a gain-of-function variation that lengthens circadian period.
In addition to these findings, Familial Natural Short Sleep (FNSS) is another heritable sleep trait that has been studied over the past few years. In 2009, Ying-Hui Fu and Ptáček discovered the first short-sleep gene by identifying a mutation in the DEC2 gene that resulted in an average of 6.25 hours of sleep a night instead of 8.06 hours, an identifying feature of FNSS. This was the first genetic discovery for this sleep trait, broadening the scope of familial sleep trait research. In 2019, Ptáček and Fu published further research about the genetic aspect of FNSS, identifying a mutation in the gene ADRB1 that increases the activity of ADRB1+ neurons in the dorsal pons.
Most of the research conducted thus far has been surrounding FASP, FDSP, and FNSS, with recent studies beginning to examine the roles of heritable sleep variability on autism-spectrum disorder (ASD) and Alzheimer's disease (AD). ASD, a neurodevelopmental disorder, has evidence of genetic components and affected individuals have reported a high prevalence of insomnia. Fu, Ptáček, and colleagues have hypothesized that it may be interesting to examine if sleep traits and disruptions can exacerbate the atypical neurodevelopment in ASD. Additionally, recent research about AD, a neurodegenerative disease, has suggested that sleep disruption might contribute to the disease. A characteristic factor of AD is the accumulation of plaques. These plaques are usually at a lower level in the brain interstitial space when an individual first wakes up and then during waking hours these levels increase. Sleep disruption can eliminate the reduction in levels, which is important during disease progression. Both ASD and AD demonstrate how the heritability of sleep traits may also be involved in disorders and diseases that are not traditionally thought of as circadian, but more research must be done in this field.
Heritable sleep traits
The functions of heritability for many sleep traits are not well known, underscoring the importance of continued research into the human genome.
Familial Advanced Sleep Phase
Familial Advanced Sleep Phase (FASP) results in an individual having a circadian clock that is entrained to their surroundings, but gives the impression that the individual is not. This trait typically develops during middle age, and is more common in older adults. Affected individuals typically have a free-running period of about 22 hours, shorter than the average person who has a free-running period closer to 24 hours. This also means that certain physiological markers, such as body temperature and melatonin will be present at higher levels earlier in the day as compared to an average person.
Symptoms
FASP is typically characterized by excessively early sleep and wake times. Additionally, individuals may experience excessive daytime sleepiness if they are forced to adhere to a schedule offset from their personal biological clock. Individuals with FASP are typically phase advanced by 4 to 6 hours as compared to the average person.
Treatments
FASP is traditionally treated with light therapy in the evenings, or behaviorally with chronotherapy. Individuals with FASP typically need to have a two-hour delay per day to remain entrained, due to their 22-hour period. Pharmacological interventions are typically avoided due to risks associated with daytime drug-induced sleepiness.
Molecular Basis
FASP has been mapped to chromosome 2q. Genes that are known to influence the presentation of FASP are CRY2, PER2, PER3 and CK1∂. TIMELESS (hTIM) has also been shown to cause FASP. These mutations are critical in the trait's phenotype and heritability. This trait is inherited in an autosomal dominant fashion.
Familial Delayed Sleep Phase
Familial Delayed Sleep Phase (FDSP) results in an individual having a circadian clock that is entrained to their surroundings, but gives the impression that the individual is not. The trait typically develops in adolescence. Affected individuals have a free-running period that is longer than the average 24 hours, meaning that certain physiological markers, such as body temperature and melatonin, are present in higher levels later in the day as compared to the average person.
Symptoms
FDSP is typically characterized by excessively late sleep times and wake times, and may include daytime sleepiness if the individual is forced to adhere to a schedule offset from their personal biological clock. Individuals with FDSP may have comorbidities with depression, Attention Deficit Hyperactivity Disorder (ADHD), obesity, and Obsessive-Compulsive Disorder (OCD).
Treatments
Treatment is usually non-pharmacological, with light therapy being a common intervention. Phase delay chronotherapy is also occasionally used. Melatonin taken at night will not change the individual's circadian rhythm, but may act as a temporary solution.
Molecular Basis
FDSP is heritable and linked to mutations in the PER3 and CRY1 genes, which result in the delayed sleep phenotype.
Fatal Familial Insomnia
Fatal Familial Insomnia (FFI) is a disorder that results in trouble sleeping, speech and coordination problems, and eventually dementia. Most of those affected die within a few years, and the disorder has no cure. The disorder can manifest any time from age 18 to 60, but the average age of affected individuals is 50 years old.
Symptoms
The disorder has a 4-stage progression, starting with individuals experiencing insomnia, progressing to seeing hallucinations, then inability to sleep and dramatic weight loss, and finally dementia, which is followed by death. Individuals have a 6-36 month prognosis after they begin experiencing symptoms.
Treatments
Due to the prognosis of the disorder, treatment is often minimal and palliative in nature. Sleeping pills and other traditional treatments are not found to be beneficial in treating FFI.
Molecular Basis
The disorder is caused by a mutation of the PRNP gene resulting in the creation of a prion. These prions result in neurodegeneration, leading to FFI. This mutation can either occur spontaneously or be passed down in an autosomal dominant manner.
Familial Natural Short Sleep
Familial natural short sleep (FNSS) is a distinct category of habitual short sleep. Individuals with this trait usually get 4–6.5 hours of sleep per day but do not have daytime sleepiness and do not need catch-up sleep on the weekends. After sleep deprivation, these individuals have less of a sleep deficit than individuals without FNSS. Additionally, affected individuals have a higher behavioral drive, resulting in many holding high pressure jobs, and they may have a better ability to deal with stress. People with FNSS are commonly mistaken for having insomnia. The prevalence of FNSS is currently unknown, however mutations in the genes DEC2 and ADRB1, NPSR1, and GRM1 have been linked to FNSS.
Symptoms
FNSS is unique because individuals with this sleep trait show no symptoms of shorter sleep. They are able to be active and function normally.
Treatments
FNSS may be seen as advantageous rather than detrimental to some individuals. Therefore, because FNSS does not negatively impact most affected individuals, treatment options for it have not been well researched or documented.
Health effects
Such mutations appear to reduce Alzheimer's pathology in mice.
Molecular Basis
In 2009, Ying-Hui Fu and colleagues described how a genetic variant in DEC2 produced the short sleep phenotype. In this variant, an arginine residue is substituted for a proline residue typically present at position 384. Within the family studied, people having the DEC2 mutation had shorter sleep durations. The researchers found the same phenotype when mutating this gene in Drosophila and mice. Interestingly, they found that the mutant mice did not display changes in their free-running activity period. DEC2 functions as a transcriptional repressor and increases expression of hypocretin, which promotes a waked state. DEC2 inhibits CLOCK/BMAL1 activation of PER, through protein-protein interaction or competition for the E-box transcriptional elements. A separate study using dizygotic twins with a novel DEC2 mutation showed that one twin had shorter sleep duration. These results demonstrate that DEC2 is able to affect sleep length through weakened transcriptional repression.
Another important gene involved in FNSS is ADRB1. ADRB1 neurons in mice are active they are awake and are found in the dorsal pons. Through additional family studies, mutations in ADRB1 have shown the reduced sleep phenotype.
In a more recent study done by Lijuan Xing and colleagues, NPSR1 was linked to FNSS. In this study, researchers identified a family with a mutation in the NPSR1 gene, which caused a short sleep phenotype. NPSR1 is a G-protein coupled receptor that plays a role in arousal and sleep behaviors. This NPSR1 mutation was recreated in mice, and the researchers found the same short sleep phenotype present.
In another study done by Guangsen Shi and colleagues, GRM1 was linked to FNSS. Here, researchers identified two GRM1 mutations in two different FNSS families. They recreated these same mutations in mouse models and found that they caused the mice to sleep less.
Understanding how these individuals are able to tolerate higher sleep pressure and behavioral drive will prove useful for numerous people that hold jobs which require long durations of wakefulness.
Familial Natural Long Sleep
Familial natural long sleep (FNLS) likely exists, however there have not been any genetic variants found that cause FNLS. People with FNLS likely need more than 8 hours of sleep per day to feel well rested. This group of individuals may be harder to detect due to comorbidities, such as depression. Additional research is necessary to learn more about this sleep trait.
See also
Chronobiology
Irregular sleep-wake rhythm
Non-24-hour sleep-wake disorder
Shift work sleep disorder
Jet lag
Sleep epigenetics
References
Hereditarianism
Circadian rhythm
Sleep physiology | Familial sleep traits | [
"Biology"
] | 3,361 | [
"Behavior",
"Sleep physiology",
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67,467,374 | https://en.wikipedia.org/wiki/Bounded%20rationality%20in%20environmental%20decision%20making | Bounded rationality in environmental decision making is the application of bounded rationality as it relates to environmental policy decisions.
Background
Bounded rationality is the idea that rationality is limited when individuals make decisions. Limitations include the difficulty of the decision problem, the cognitive capability of the mind, and the time available to make the decision. This idea can be applied in any field that involves decision making, such as behavioral economics, cognitive psychology, and environmental policy. Established environmental policy theory is based on the assumption of homo economicus. This means that people are seen as fully rational and acting in a self-regarding manner. This assumption can be troublesome when making environmental policy because policymakers often have an incomplete picture about a given environmental problem. In Gigerenzer et al.'s 2001 book, Bounded Rationality: The Adaptive Toolbox, they define a perfectly rational actor as "requiring unlimited cognitive capabilities. Fully rational man is a mythical hero who knows the solutions to all mathematical problems and can immediately perform all computations, regardless of how difficult they are." All environmental actors are human beings, therefore do not have unlimited cognitive abilities, and are prone to making decisions with incomplete information. The more actors that are involved with an environmental decision, the more complex that decision becomes, and the outcomes become less predictable.
Policy making
The health of the environment is not the only thing in consideration when making environmental policy; other elements are considered such as economics. According to the Porter hypothesis, strict environmental regulations may induce competitiveness among firms, leading to technological innovations that produce cleaner byproducts and less overall harm to the environment. Policies that follow this hypothesis tend to fall under the category of a "green strategy", where the marginal abatement cost is greater than the damage caused to the environment. Some environmental policy decisions are made to have weaker regulations, resulting in a more stimulated resource export economy known as eco-dumping. Eco-dumping is the opposite of a green strategy, where the marginal abatement cost is less than the damaged caused to the environment. These approaches offer two extremes in environmental policy, where multifaceted wicked problems are attempted to be solved by single-faceted policy.
References
Behavioral economics
Economics of sustainability | Bounded rationality in environmental decision making | [
"Biology"
] | 446 | [
"Behavior",
"Behavioral economics",
"Behaviorism"
] |
67,467,960 | https://en.wikipedia.org/wiki/Anidex | Anidex is one of the elastomeric synthetic fibers. It is made from an artificial linear polymer consisting of at least 50% by mass of one or more monohydric alcohol esters.
Development
Rohm and Haas developed Anidex in 1969. The company could not produce it commercially because of lacking differences in properties to become an economic success.
Properties
Anidex is a stretchable fiber with good elasticity and recovery, but it was lesser than its counterparts, for instance, spandex. Anidex has good resistance to chemicals, sunlight, and heat, which was better than spandex and rubber. The fiber was possible to blend with many natural and synthetic fibers. It is easy to handle and care for.
Application
Because of its stretching properties It is a useful fiber for textiles. The fiber provides extra elasticity to the blends and makes them more functional, and aids in designing such as upholstery material fits better to the furniture.
See also
Acrylic fiber
Spandex
References
Fibers
Polymers
Elastomers
Synthetic fibers | Anidex | [
"Chemistry",
"Materials_science"
] | 217 | [
"Synthetic fibers",
"Synthetic materials",
"Elastomers",
"Polymer chemistry",
"Polymers"
] |
67,468,472 | https://en.wikipedia.org/wiki/Estonian%20Air%20Sports%20Federation | Estonian Air Sports Federation (abbreviation EASF; ) is one of the sport governing bodies in Estonia which deals with air sports.
EASF is a member of World Air Sports Federation (FAI) and a member of Estonian Olympic Committee.
References
External links
Sports governing bodies in Estonia
Aviation in Estonia
Fédération Aéronautique Internationale | Estonian Air Sports Federation | [
"Engineering"
] | 64 | [
"Fédération Aéronautique Internationale",
"Aeronautics organizations"
] |
67,469,176 | https://en.wikipedia.org/wiki/Reverse%20complement%20polymerase%20chain%20reaction | Reverse complement polymerase chain reaction (RC-PCR) is a modification of the polymerase chain reaction (PCR). It is primarily used to generate amplicon libraries for DNA sequencing by next generation sequencing (NGS). The technique permits both the amplification and the ability to append sequences or functional domains of choice independently to either end of the generated amplicons in a single closed tube reaction. RC-PCR was invented in 2013 by Daniel Ward and Christopher Mattocks at Salisbury NHS Foundation Trust, UK.
Principles
In RC-PCR, no target specific primers are present in the reaction mixture. Instead target specific primers are formed as the reaction proceeds. A typical reaction employing the approach requires four oligonucleotides. The oligonucleotides interact with each other in pairs; one oligonucleotide probe and one universal primer (containing functional domains of choice), which hybridize with each other at their 3’ ends. Once hybridized, the universal primer can be extended, using the oligonucleotide probe as the template, to yield fully formed, target specific primers, which are then available to amplify the template in subsequent rounds of thermal cycling as per a standard PCR reaction.
The oligonucleotide probe may also be blocked at the 3’ end preventing equivalent extension of the probe, but this is not essential. The probe is not consumed; it is available to act as a template for the universal primer to be ‘converted’ into target specific primer throughout successive PCR cycles. This generation of target specific primer occurs in parallel with standard PCR amplification under standard PCR conditions.
Advantages
RC-PCR provides significant advantages over other methods of amplicon library preparation methods. Most significantly it is a single closed tube reaction, this eliminates cross contamination associated with other two-step PCR approaches as well as utilising less reagent and requiring less labour to perform.
The technique also provides the significant advantage of the flexibility of appending any desired sequence or functional domain of choice to either end of any amplicon. This is currently most advantageous in modern next generation sequencing (NGS) laboratories where a single target specific probe pair can be used with a whole library of universal primers. This benefit is used with NGS applications to apply sample specific indexes independently to each end of the amplicon construct. A Laboratory employing this approach would only require a single set of index primers, which can be used with all target specific probes compatible with that index set. This significantly reduces the number and length of oligonucleotides required by the laboratory compared to using full length pre-synthesised indexed target specific primers.
The generation of the target specific primer in the reaction as it progresses also leads to more balanced reaction components. Concentrations of target specific primer are more aligned with target molecule concentration thereby reducing the potential of both off target priming and primer dimerisation.
Variations
Multiplex RC-PCR – where two or more universal primer probe sets are present in the reaction mixture to amplify two or more targets simultaneously.
RT-RC-PCR – This modification is used when the template material supplied in the reaction is RNA rather than DNA. In this modification the reaction mixture also contains reverse transcriptase enzymes and reverse transcription primers as well as the universal primers and Reverse complement probes of the method. This approach permits reverse transcription of the provided RNA template, the formation of tailed target specific primers and the amplification of the desired targets in a single closed tube reaction.
Single ended RC-PCR – This variation of the method is used when only one complementary universal primer probe pair is provided in the reaction to generate one target specific primer. The other target specific primer is provided as a traditional primer as per standard PCR.
History
Following the invention of RC-PCR in 2013 the technique was clinically validated and employed diagnostically for a range of both inherited diseases such as hemochromatosis and thrombophilia as well as somatically acquired disorders including Myeloproliferative neoplasms and Acute myeloid leukemia in the Wessex Regional Genetics Laboratory (WRGL), Salisbury UK. More recently work has been undertaken to utilise the technology in the fight against the SARS-CoV-2 pandemic.
The patent application was filed in the UK in 2015 and awarded in 2020. Patent applications have been filed in other jurisdictions worldwide and are currently pending.
In May 2019 the Intellectual property was licensed to Nimagen B.V. to develop, manufacture and market kits exploiting the technology. Currently commercially available kits employing the technology include those for Human identification and for the whole genome sequencing of the SARS-CoV-2 virus for variant identification, tracking and treatment response. In August 2022 Nimagen officially launched a range of products employing the RC-PCR technology for human forensics applications under the trademark IDseek®. The Short Tandem Repeat version of the kit is validated by the Netherlands Forensic Institute as an improved method for routine massively parallel sequencing of short tandem repeats.
The RC-PCR approach is becoming more widely used for human health and several CE IVD kits are available for human clinical diagnostics including BRCA, TP53, PALB2 and CFTR analysis. The technique has also been proven as a useful and powerful tool in the identification of the causative infectious pathogen in patients suspected of having a bacterial infection, in this setting it has been shown to provide a significant increase in the number of clinical samples in which a potentially clinically relevant pathogen is identified compared to the commonly used 16S Sanger method. It has also been shown to provide similar advantages over traditional methods in the deconvolution of microbial communities in environmental samples.
References
External links
RC-PCR animation
WIPO patent filing information page
Polymerase chain reaction
SARS-CoV-2
DNA sequencing methods
Molecular biology techniques
DNA profiling techniques
Laboratory techniques
Amplifiers
British inventions | Reverse complement polymerase chain reaction | [
"Chemistry",
"Technology",
"Biology"
] | 1,241 | [
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"Genetics techniques",
"DNA profiling techniques",
"Polymerase chain reaction",
"DNA sequencing methods",
"Molecular biology techniques",
"DNA sequencing",
"nan",
"Molecular biology",
"Amplifiers"
] |
56,150,063 | https://en.wikipedia.org/wiki/Redmi%20Note%205A | Xiaomi Redmi Note 5A is a smartphone developed by Xiaomi Inc. in Xiaomi's low-end Redmi smartphone line. It has two variants, the cheaper Redmi Note 5A with Snapdragon 425 SoC, and the more expensive Redmi Note 5A Prime with Snapdragon 435.
The phone has been renamed to Redmi Y1 in India, where film star Katrina Kaif launched the Redmi Y line of smartphones in Delhi on November 2, 2017.
The company superseded it with the upgraded successors Redmi 6/6A/6 Pro and Redmi Note 6/6 Pro, and further models later.
Specifications
Hardware
The Xiaomi Redmi Note 5A has a 5.5-inch IPS LCD display, Quad-core 1.4 GHz processor(Model: mdg6), 2GBof RAM and 16GB of internal storage or Octa-core 1.4 GHz Cortex-A53 Qualcomm Snapdragon 435 processor, 3/4 GB of RAM and 32/64 GB of internal storage that can be expanded using microSD cards up to 256 GB. The phone has a 3080 mAh Li-ion battery, a 13 MP rear camera with LED flash and 16 MP front-facing camera with auto-focus. It is available in Gold, Dark Grey, Silver, Rose Gold colors.
Software
On release Redmi Note 5A and Note 5A Prime worked on MIUI 8 based on Android 7.1.2. They were updated to MIUI 11.
Sales
Xiaomi Redmi Note 5A went on sale in August 2017. The price was pegged at RMB 699 for the base model and RMB 899 for the Prime variant.
Xiaomi sold over 150,000 units of Redmi Note 5A and Redmi Note 5A Prime in 3 minutes after the India release on November 8, 2017.
Gallery
References
External links
Redmi Note 5A Specification
Phablets
Note 5A
Mobile phones introduced in 2017
Discontinued smartphones
Mobile phones with infrared transmitter | Redmi Note 5A | [
"Technology"
] | 416 | [
"Crossover devices",
"Phablets"
] |
56,150,440 | https://en.wikipedia.org/wiki/Ethylidene%20norbornene | Ethylidene norbornene (ENB) is an organic compound that consists of an ethylidene (CH3C(H)=) group attached to norbornene. It is a colorless liquid. The molecule consists of two sites of unsaturation. The compound consists of (E)- and (Z)-stereoisomers, but the mixtures are typically not separated.
Preparation and use
It is prepared by isomerization of vinyl norbornene, which in turn is obtained by the Diels-Alder reaction of butadiene and cyclopentadiene.
It is a monomer that used in the production of the commercial polymer EPDM. Only the ring alkene participates in the copolymerization. The exocyclic double bond (the ethylidene group) undergoes sulfur vulcanization.
Safety
Its (intravenous, rabbit) ranges from 0.09 (male rabbit) to 0.11 ml/kg (female). It is also a neurotoxin.
References
Cyclopentenes
Monomers | Ethylidene norbornene | [
"Chemistry",
"Materials_science"
] | 224 | [
"Monomers",
"Polymer chemistry"
] |
56,151,614 | https://en.wikipedia.org/wiki/Sirius%20%28synchrotron%20light%20source%29 | Sirius is a diffraction-limited storage ring synchrotron light source at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, São Paulo State, Brazil. It has a circumference of , a diameter of , and an electron energy of 3 GeV. The produced synchrotron radiation covers the range of infrared, optical, ultraviolet and X-ray light.
Costing R$1.8 billion, it was funded by the Ministry of Science, Technology, Innovation and Communications (Brazil) and the São Paulo Research Foundation. Discussion started in 2008, and initial funding of R$2 million was granted in 2009. Construction started in 2015, and was finished in 2018. The first electron loop around the storage ring was achieved in November 2019. Its first experiments were made during COVID-19 pandemic at MANACÁ beamline, dedicated to macromolecular crystallography.
Sirius is the second synchrotron lightsource constructed in Brazil. The first one, UVX, was a second-generation machine operated by LNLS from 1997 to 2019.
History
In 2008, LNLS former director José Antônio Brum asked for a preview of a new accelerator, which was then shown to the minister of science Sérgio Machado Rezende. Construction began in 2014 under the Dilma Rousseff government. Sirius is the second operational particle accelerator in Brazil, the first one being the UVX..
The first part of the complex was inaugurated on 14th November 2018 by then-president Michel Temer, and included the main building and two of the three accelerators. The second part included the third accelerator, the storage ring and the commissioning of the first beamlines. Sirius currently operates at 100mA in top-up mode and has 6 beamlines open to external researchers.
Characteristics
Sirius is used to understand the atomic structure of molecules, which can help in the development of new drugs, new materials used in construction, oil exploration and in many other areas. The 68,000-square-meter building houses a ring-shaped, circumferential 500-meter facility. To protect people from the radiation released by machine operation, designed to be the most advanced of its kind in the world, the whole is shielded by 1 kilometer of concrete walls. Around R$1.8 billion were invested in the project, which makes it the most ambitious scientific project ever made in Brazil.
Beamlines
Currently, Sirius has 9 operational beamlines, 1 in scientific commissioning, 2 in the assembly phase and 1 the design phase.
References
External links
Synchrotron radiation facilities
Science and technology in Brazil | Sirius (synchrotron light source) | [
"Physics",
"Materials_science"
] | 536 | [
"Particle physics stubs",
"Materials testing",
"Particle physics",
"Synchrotron radiation facilities"
] |
56,152,466 | https://en.wikipedia.org/wiki/Bruceolide | Bruceolide is a quassinoid that has been isolated from Bischofia javanica. Synthetic derivatives have shown in vitro antimalarial activity.
References
Quassinoids
Heterocyclic compounds with 5 rings | Bruceolide | [
"Chemistry"
] | 48 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
56,155,535 | https://en.wikipedia.org/wiki/API%20Standard%20682 | API Standard 682, titled "Pumps - Shaft Sealing Systems for Centrifugal and Rotary Pumps," is the American Petroleum Institute (API) standard for end-face mechanical seals. The purpose of API 682 is to assist in the selection and operation of end face mechanical seals in centrifugal pumps. It is based on the combined knowledge and experience of seal manufacturers, engineering companies, and end users. API 682 is primarily intended for use in the petroleum, natural gas and chemical industries, but is often referenced for other types of equipment and industries.
The API has approximately 500 technical standards for processes and components.
Background and development
By the late 1980s, mechanical seals had been accepted as the preferred method for sealing rotating pumps for many years. However, mechanical seal standards were generally buried in other standards such as DIN 24960, ANSI B73, and API 610. All of these standards were primarily pump standards and any references to seals were directed at how mechanical seals would interact with pumps.
API 610 is the API standard about centrifugal pumps and is primarily intended for use in the petroleum, natural gas and chemical industries. Although the 1st through 7th Editions of API 610 included specifications for mechanical seals, beginning with the 8th Edition, API 610 defers to API 682 for seal specifications.
In the late 1980s a group of refinery equipment engineers and managers began to compare sealing solutions in refinery applications. This group, led by V. R. Dodd of Chevron, came up with a general plan and the American Petroleum Institute (API) agreed to establish a standard for mechanical seals: API 682. A Task Force was formed in 1990 and the first meeting was held in January 1991. This Task Force was composed of fourteen members from various refineries, seal and pump manufacturers. API 682, First Edition, was published in October 1994.
One interesting aspect of API 682 is that it includes a strong set of defaults. That is, unless the user indicates otherwise, API 682 makes default choices for specifics such as:
Seal type
Rotating or stationary
Seal arrangement
Seal configuration/orientation
Materials
Piping plan
… many others.
Some statements within API 682 are normative, that is, required, whereas others are informative, that is, descriptive but not required. In particular, many of the illustrations are informative. This distinction has not always been apparent to the reader.
Subsequent editions of API 682 have been published. The current edition is 4th Edition.
API 682 1st edition
The first edition of API 682 was entirely new although parts of it were extracted from the pump standard API 610 and existing API standard paragraphs.
The mission statement for the 1st Edition was:
"This standard is designed to default to the equipment types most commonly supplied that have a high probability of meeting the objective of at least three years of uninterrupted service while complying with emissions regulations."
Although this mission statement no longer appears in the standard, it remains the basic principle driving the work of the API 682 Task Force and its relevance remains the same for the 4th Edition as it did for the 1st.
In addition to providing requirements for mechanical seals, the 1st Edition of API 682 also provided a guide on how to select the correct seal for a number of common refinery applications. In order to provide this seal selection guide, it was necessary to categorize applications into a number of services:
Non-hydrocarbon
water
sour water
caustics/amines
acids
Non-flashing hydrocarbon
Flashing hydrocarbon.
It was also necessary to categorize the many different type seals that were used in these services. Three seal types were designated:
Type A – O-ring pusher
Type B – O-ring metal bellows
Type C – flexible gasket (high temperature) metal bellows.
Prior to API 682, 1st Edition, multiple seals were designated as being either “tandem” or “double” seals; however, advances in seal design had rendered these classic terms obsolete. As a result, there was some confusion on how multiple seals were designated. The task force decided to use a more descriptive designation and chose to define dual seal arrangements. A dual seal would be two sets of sealing faces used in the same seal chamber. The fluid between these two sets of sealing faces could be either pressurized or unpressurized. Three standard arrangements were defined:
Arrangement 1 is a single seal
Arrangement 2 is a dual unpressurized seal
Arrangement 3 is a dual pressurized seal.
API 682 1st Edition did not include containment seals or dry gas barrier seals.
After having defined the services, seal types, and seal arrangements, a series of flowcharts were created to help in selecting a seal type, special materials or design requirements, and supporting piping plans.
API 682 seals were to have a high probability of three years of reliable service. In order to prove this, seal performance testing on process fluids under representative pressures and temperatures was required. These performance tests are called “Qualification Tests”.
The general idea of the qualification test was to prove that the design was sound. The goal of the qualification test was to simulate a long-term steady state run followed by a process upset. The simulated process upset consisted of pressure changes, temperature changes and included loss of flush. The results of these tests were made available to the purchaser for evaluation. There was no acceptance criteria presented in API 682 1st Edition.
In addition to the qualification test of the design, every API 682 seal, whether new or repaired, is to be pressure tested with air before being shipped to the end user.
API 682 2nd edition
One of the major criticisms of API 682 1st Edition was that all the seals were “heavy duty” and therefore expensive with no alternatives for easy services. To some degree, this was intentional and was done in order to reduce inventory, promote familiarity with a limited number of seal types and to increase reliability. Another criticism of API 682 1st Edition was that it considered only API 610 pumps and only refinery applications. The chemical and petrochemical industries routinely use ASME pumps in addition to API 610 pumps. Broadening the scope of pumps covered by API 682 would allow standardized seals to be applied in a greater number of industries.
In 2nd Edition, the organization of API 682 was changed to conform to ISO standards: This reorganization means that there is no simple cross reference guide between 1st edition and 2nd edition paragraph numbers.
Categories
The 2nd Edition introduced the concept of seal categories. A seal category describes the type of pump into which the seal will be installed, the operating window, the design features, and the testing and documentation requirements. There are three categories designated as Category 1, 2, or 3.
Category 1 seals are intended for non-API-610 pumps. This category is applicable for temperatures between –40 °F and 500 °F (-40 °C and 260 °C) and pressures to 315 PSI (22 bar).
Category 2 seal are intended for API-610 This category is applicable for temperatures between –40 °F and 750 °F (-40 °C and 400 °C) and pressures to 615 PSI (42 bar).
Category 3 seals are essentially the original seals of 1st Edition and are also intended for API-610 pumps. Category 3 seals are intended for the most demanding applications. This category is applicable for temperatures between –40 °F and 750 °F (-40 °C and 400 °C) and pressures to 615 PSI (42 bar). Design features include a distributed flush and floating throttle bushing for single seals. Additional documentation must be also provided.
New seal types
Three new seal types were introduced in the 2nd Edition: dry running containment seals, non-contacting seals, and dual gas barrier seals.
Containment seals are the outer seal of Arrangement 2. In the 2nd Edition, containment seals can be used with a liquid buffer fluid, a gas buffer fluid or without a buffer fluid. In the case of a dry running containment seal, the containment seal will be exposed primarily to buffer gas or vaporized process fluid. Such containment seals must therefore be designed for continuous dry running while meeting the reliability goals of the standard. Dry running containment seals may be either contacting or non-contacting.
Non-contacting inner seals are also introduced for Arrangement 2. One of the primary targets for non-contacting inner seals is in flashing hydrocarbon services. In some of these services, it is impossible to obtain adequate vapor margins to prevent flashing of the fluid in the seal chamber. This seal will be used with a dry running containment seal and the leakage past the inner seal will be piped to a vapor recovery system.
The other new seal type introduced in 2nd Edition was the dry running gas seal used in Arrangement 3. This seal is designed to run on a gas barrier fluid such as nitrogen.
New piping plans
Several new piping plans were introduced in the 2nd Edition. These included additional options for dual pressurized liquid seals as well as new piping plans to support containment seals and dual pressurized gas seals.
New qualification procedures
One of the strengths of the 1st Edition was to provide qualification tests in which seal vendors would be required to prove the suitability of their seals for a given service. The 2nd Edition expanded on these requirements by adding new tests for containment seals and dual gas seals as well as defining acceptance criteria for all tests.
API 682 3rd edition
For all practical purposes, API 682 3rd Edition is the same as 2nd Edition. The completed 2nd Edition was submitted to the ISO Organization for approval as their ISO 21049. At the time, API and ISO had an agreement to jointly issue standards. The ISO Organization made slight editorial changes to 2nd Edition, including correcting typographical errors and unit conversions. Therefore, API had to re-issue a corrected 2nd edition but choose to label it as 3rd edition. API 682 3rd Edition was published in September 2004.
API and ISO no longer have the agreement to jointly issue standards. The 2004 issue of ISO 21049 is the only issue and plans to update it are unknown.
API 682 4th edition
A twenty-five member task force spent six years updating 3rd Edition to 4th Edition. The 4th Edition of API 682 is organized similarly to the 2nd and 3rd Editions:
Scope
Normative references
Terms, Definitions, and Symbols
Sealing Systems
General
Design Requirements
Specific Seal Configurations
Accessories
Instrumentation
Inspection, Testing, and Preparation for Shipment
Data Transfer
Annexes
Annex A – Recommended Seal Selection Procedure
Annex B – Typical Materials and Material Specifications
Annex C – Mechanical Seals Datasheets
Annex D – Seal Codes
Annex E – Mechanical Seals Data Requirement Forms
Annex F – Technical Tutorials and Illustrative Calculations
Annex G – Standard Piping Plans and Auxiliary Hardware
Annex H – Inspectors’ Checklist for All Seals
Annex I – Seal Qualification Testing
Configurations
Seal Configuration refers to the orientation of the seal components in an assembly. In previous editions, orientations were defined as face-to-back, back-to-back, and face-to-face and these terms are carried over into the 4th Edition. In 4th Edition, any orientation (face to back, back to back, face to face) can be used in a dual seal provided that the design features are appropriate to the functionality of that particular arrangement.
Clearances
Fourth Edition added additional specifications for clearances, placed these requirements in the form of tables and noted that seal components are not to be considered as “shaft catchers” to restrict shaft movement. The minimum clearances specified apply only to equipment within the scope of the standard. Equipment outside that scope, such as non-cartridge seals, older pumps, non-API 610 pumps and certain severe services, might benefit from larger clearances.
Codes
Before API 682, API 610 (the pump standard) used a simple seal code to specify seals. API 682 attempted to use a more comprehensive seal code; however, that code changed with every edition of API 682. The 4th Edition code, described in Annex D, is probably the best to date and includes some concepts and codes from the historical API 610 seal code. The new code uses eight fields:
Seal category
Seal arrangement
Seal type
Containment device
Gasket material
Face material
Approximate shaft size (in millimeters)
Piping plan
As an example, the 4th Edition code might be 31B-LIN-075-53A to indicate:
3 – Category 3
1 – Arrangement 1
B – Type B seal
L – Floating bushing
I – FFKM secondary seals
N – Carbon vs reaction bonded silicon carbide
075 – installed on a 75 mm shaft
53A – Plan 53A
Piping plans
Annex G provides illustrations and a short tutorial about each piping plan. As has been the case for every edition, changes were made to the standard piping plans. In particular, the piping plans now default to using transmitters with local indicators as part of the instrumentation.
Future editions
API standards are reviewed every five years and re-issued every ten years. A new Taskforce for API 682 was formed in 2017 and preparations for 5th Edition are underway.
References
Seals (mechanical)
Oil industry standards
American Petroleum Institute | API Standard 682 | [
"Physics"
] | 2,640 | [
"Seals (mechanical)",
"Materials",
"Matter"
] |
56,157,463 | https://en.wikipedia.org/wiki/Gutolactone | Gutolactone is a chemical compound extracted from Simaba guianensis and it has displayed antimalarial properties in vitro.
References
Quassinoids
Heterocyclic compounds with 5 rings
Triols | Gutolactone | [
"Chemistry"
] | 45 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
56,157,624 | https://en.wikipedia.org/wiki/Plant%20Biotechnology%20Journal | Plant Biotechnology Journal, an Open Access journal, publishes high-impact original research and incisive reviews with an emphasis on molecular plant sciences and their applications through plant biotechnology. It was established in 2003 and is published by Wiley-Blackwell in association with the Society for Experimental Biology and the Association of Applied Biologists. The editor-in-chief is Henry Daniell (University of Pennsylvania). According to the Journal Citation Reports, the journal has a 2021 impact factor of 13.263, ranking it 5th out of 238 journals in the category "Plant Sciences" and 8th out of 158 journals in the category "Biotechnology & Applied Microbiology". As an Open Access journal, articles are accessible globally without restriction. To cover the cost of publishing, Plant Biotechnology Journal charges a publication fee.
References
External links
Botany journals
Biotechnology journals
English-language journals
Wiley-Blackwell academic journals
Academic journals established in 2003
Academic journals associated with international learned and professional societies of Europe | Plant Biotechnology Journal | [
"Biology"
] | 190 | [
"Biotechnology literature",
"Biotechnology journals"
] |
77,580,922 | https://en.wikipedia.org/wiki/White%20phosphorus | White phosphorus, yellow phosphorus, or simply tetraphosphorus (P4) is an allotrope of phosphorus. It is a translucent waxy solid that quickly yellows in light (due to its photochemical conversion into red phosphorus), and impure white phosphorus is for this reason called yellow phosphorus. White phosphorus is the first allotrope of phosphorus, and in fact the first elementary substance to be discovered that was not known since ancient times. It glows greenish in the dark (when exposed to oxygen) and is highly flammable and pyrophoric (self-igniting) upon contact with air. It is toxic, causing severe liver damage on ingestion and phossy jaw from chronic ingestion or inhalation. The odour of combustion of this form has a characteristic garlic odor, and samples are commonly coated with white "diphosphorus pentoxide", which consists of tetrahedra with oxygen inserted between the phosphorus atoms and at their vertices. White phosphorus is only slightly soluble in water and can be stored under water. is soluble in benzene, oils, carbon disulfide, and disulfur dichloride.
Structure
White phosphorus exists as molecules of four phosphorus atoms in a tetrahedral structure, joined by six phosphorus—phosphorus single bonds. The tetrahedral arrangement results in ring strain and instability. Although both are called "white phosphorus", in fact two different crystal allotropes are known, interchanging reversibly at 195.2 K. The element's standard state is the body-centered cubic α form, which is actually metastable under standard conditions. The β form is believed to have a hexagonal crystal structure.
Molten and gaseous white phosphorus also retains the tetrahedral molecules, until when it starts decomposing to molecules. The molecule in the gas phase has a P-P bond length of rg = 2.1994(3) Å as was determined by gas electron diffraction. The β form of white phosphorus contains three slightly different molecules, i.e. 18 different P-P bond lengths — between 2.1768(5) and 2.1920(5) Å. The average P-P bond length is 2.183(5) Å.
Chemical properties
Despite white phosphorus not being the most stable allotropes of phosphorus, its molecular nature allows it to be easily purified. Thus, it's defined to have a zero enthalpy of formation.
In base, white phosphorus spontaneously disproportionates to phosphine and various phosphorus oxyacid salts.
Many reactions of white phosphorus involve insertion into the P-P bonds, such as the reaction with oxygen, sulfur, phosphorus tribromide and the NO+ ion.
It ignites spontaneously in air at about , and at much lower temperatures if finely divided (due to melting-point depression). Phosphorus reacts with oxygen, usually forming two oxides depending on the amount of available oxygen: (phosphorus trioxide) when reacted with a limited supply of oxygen, and when reacted with excess oxygen. On rare occasions, , , and are also formed, but in small amounts. This combustion gives phosphorus(V) oxide:
Production and applications
The white allotrope can be produced using several methods. In the industrial process, phosphate rock is heated in an electric or fuel-fired furnace in the presence of carbon and silica. Elemental phosphorus is then liberated as a vapour and can be collected under phosphoric acid. An idealized equation for this carbothermal reaction is shown for calcium phosphate (although phosphate rock contains substantial amounts of fluoroapatite, which would also form silicon tetrafluoride):
In this way, an estimated 750,000 tons were produced in 1988.
Most (83% in 1988) white phosphorus is used as a precursor to phosphoric acid, half of which is used for food or medical products where purity is important. The other half is used for detergents. Much of the remaining 17% is mainly used for the production of chlorinated compounds phosphorus trichloride, phosphorus oxychloride, and phosphorus pentachloride:
Other products derived from white phosphorus include phosphorus pentasulfide and various metal phosphides.
Other polyhedrane analogues
Although white phosphorus forms the tetrahedron, the simplest possible Platonic solid, no other polyhedral phosphorus clusters are known. White phosphorus converts to the thermodynamically-stabler red allotrope, but that allotrope is not isolated polyhedra.
A cubane-type cluster, in particular, is unlikely to form, and the closest approach is the half-phosphorus compound , produced from phosphaalkynes. Other clusters are more thermodynamically favorable, and some have been partially formed as components of larger polyelemental compounds.
Safety
White phosphorus is rather acutely toxic, with a lethal dose of 50-100 mg (1 mg/kg body weight). Its mode of action is thought to involve its reducing properties. It is metabolized to phosphate, which is not toxic.
White phosphorus is used as a weapon because it is pyrophoric. For the same reasons, it is dangerous to handle. Measures are taken to protect samples from air. Anecdotal report of problems for beachcombers who may collect washed-up samples while unaware of their true nature.
See also
Red phosphorus
Allotropes of phosphorus
Phosphorus
References
Allotropes | White phosphorus | [
"Physics",
"Chemistry"
] | 1,140 | [
"Periodic table",
"Properties of chemical elements",
"Allotropes",
"Materials",
"Matter"
] |
77,580,960 | https://en.wikipedia.org/wiki/HD%2096063 | HD 96063 (proper name Dingolay) is a 8th-magnitude red-giant branch star located about away in the constellation of Leo. It is orbited by one confirmed exoplanet, HD 96063 b (proper name Ramajay), a gas giant slightly larger and more massive than Jupiter.
Nomenclature
In 2019, the Republic of Trinidad and Tobago was assigned to giving the HD 96063 system a proper name as part of the IAU100 NameExoWorlds Project, planned to celebrate the hundredth anniversary of the International Astronomical Union (IAU), which grants the right to name an exoplanetary system to every state and territory in the world. Names were submitted and selected within Trinidad and Tobago, which were then presented to the IAU to be officially recognized. On 17 December 2019, the IAU announced that HD 96063 and its planet, b, were named Dingolay and Ramajay, respectively.
The two names are both derived from terms related to the Trinidad and Tobago Carnival. Dingolay is a dance form that represents the culture and language of Trinidad and Tobago's ancestors via intricate movements. Ramajay is a steelpan style of singing and music that celebrates Trinidad and Tobago's forefathers' culture and language.
Stellar characteristics
HD 96063 is an evolved yellow/orange star with an effective temperature of about 5,000–5,100 K, typical of stars entering the red-giant branch. Its precise nature, however, has been controversial. Once classified as a G6-type main-sequence star, the star is more recently thought to be a K-type "yellow giant," somewhere between three and five times as large as the Sun. When the planet HD 96063 b was discovered, the star was assumed to be billion years old with a sun-like mass ( ), but subsequent studies consider it to be more massive at about 1.4 , and thus younger ( Gyr). With a luminosity roughly ten times that of the Sun and a distance of 454 light-years, the star has an apparent magnitude of 8.254, too faint to be seen from Earth by the naked eye.
Planetary system
In 2011, radial-velocity observations made at the W. M. Keck Observatory revealed the existence of an exoplanet around HD 96063. The planet, HD 96063 b, is thought to be a gas giant at least 1.265 times the mass of Jupiter, which orbits its host star at a distance of 1.11 AU with an Earth-like period of 362 days. Its orbit is moderately eccentric, with an eccentricity comparable to that of planet Mercury (0.2056).
See also
List of proper names of stars
List of proper names of exoplanets
List of stars in Leo
List of exoplanets discovered in 2011
References
External links
Dingolay
Leo (constellation)
096063
054158
BD-01 02476
K-type giants
Planetary systems with one confirmed planet
J11044445-0230475
Planetary systems
Stars | HD 96063 | [
"Astronomy"
] | 640 | [
"Leo (constellation)",
"Constellations"
] |
77,581,037 | https://en.wikipedia.org/wiki/PCB-Investigator | PCB-Investigator is a software tool used for the analysis, visualization, and optimization of printed circuit boards (PCBs). It is used for tasks such as PCB design validation and quality assurance. It is developed by EasyLogix owned by Schindler & Schill GmbH, a German company specializing in electronic design automation (EDA) software.
History
The software was introduced in 2008 to meet the increasing demand for tools that support PCB analysis and visualization. Since its release, PCB-Investigator has been updated regularly to include new features and support for various PCB file formats. The currently available version is 15.1.
Features
PCB-Investigator provides features for PCB design and manufacturing, supporting various file formats like ODB++, Gerber, and IPC-2581. It includes tools for design rule checks (DRC) and other analyses to verify compliance with industry standards. The software also offers 3D visualization of PCBs and supports scripting for task automation and workflow customization. In 2017, PCB-Investigator introduced browser-based support for PCB design reviews.
See also
Comparison of EDA software
Altium Designer
KiCad
Cadence Allegro
References
External links
Printed circuit board manufacturing | PCB-Investigator | [
"Engineering"
] | 250 | [
"Electrical engineering",
"Electronic engineering",
"Printed circuit board manufacturing"
] |
77,581,175 | https://en.wikipedia.org/wiki/Red%20phosphorus | Red phosphorus is an allotrope of phosphorus. It is an amorphous polymeric red solid that is stable in air. It can be easily converted from white phosphorus under light or heating. It finds applications as matches and fire retardants. It was discovered in 1847 by Anton von Schrötter.
Structure
Red phosphorus is an amorphous form of phosphorus. Crystalline forms of red phosphorus include Hittorf's phosphorus and fibrous red phosphorus. The structure of red phosphorus contains the fragments illustrated below:
Preparation
One method of preparing red phosphorus involves heating white phosphorus in an inert atmosphere like nitrogen or carbon dioxide, with iodine as catalyst.
Another theoretically possible method of red phosphorus production is via light irradiation of white phosphorus. However, it has not been used industrially, likely due to the suspicious quality and unidentified structure the product.
Properties
Under standard conditions, red phosphorus is more stable than white phosphorus, but less stable than the thermodynamically stable black phosphorus. The standard enthalpy of formation of red phosphorus is −17.6 kJ/mol. Red phosphorus is kinetically most stable.
Being polymeric, red phosphorus is insoluble in solvents. It shows semiconductor properties.
Due to such a kinetic stability, red phosphorus doesn't spontaneously ignite in air. It doesn't disproportionate in the presence of alkali, and is less reactive towards halogens, sulfur, and metals compared with white phosphorus.
Applications
Red phosphorus can be used as a flame retardant in resins. Its mechanism of action involves the formation of polyphosphoric acid (the hydrogen atoms are from the resin) and char, which prevents flame propagation.
However, for electronic/electrical systems, red phosphorus flame retardant has been effectively banned by major OEMs due to its tendency to induce premature failures. One persistent problem is that red phosphorus in epoxy molding compounds induces elevated leakage current in semiconductor devices. Another problem was acceleration of hydrolysis reactions in PBT insulating material.
Red phosphorus is used, along with abrasives, on the strike pads of modern safety matches. The match head, containing potassium chlorate, will ignite upon friction with the strike pad. However, the red color of the matchhead is due to addition of red dyes, and has nothing to do with red phosphorus content.
Red phosphorus reacts with bromine and iodine to form phosphorus tribromide and phosphorus triiodide. Both are useful as halogenation agents, like replacing the hydroxyl group of alcohols. Phosphorus triiodide can also be used to produce hydroiodic acid after hydrolysis. This reaction is notable in the illicit production of methamphetamine and Krokodil, where hydrogen iodide acts as a reducing agent.
Red phosphorus is often used to prepare chemicals where the P-P bond is retained. Upon room temperature action with sodium chlorite, Na2H2P2O6 is formed.
Red phosphorus can be used as an elemental photocatalyst for hydrogen formation from the water. It has also been researched as a sodium ion battery anode.
Violet or Hittorf's phosphorus
Hittorf's phosphorus, or violet phosphorus, is one of the crystalline forms of red phosphorus. It adopts the following structure:
Violet phosphorus can be prepared by sublimation of red phosphorus in a vacuum, in the presence of an iodine catalyst.
It is chemically similar to red phosphorus. There are, however, subtle differences. Violet phosphorus ignites upon impact in air, while red phosphorus is impact stable. Violet phosphorus doesn't ignite in the presence of air upon room temperature contact with bromine, unlike red phosphorus. The reaction of red phosphorus and bromine alone does not generate a flame.
Fibrous red phosphorus
Fibrous red phosphorus is another crystalline form of red phosphorus. It is obtained along with violet phosphorus when red phosphorus is sublimed in vacuum in the presence of iodine.
It is structurally similar to violet phosphorus. However, in fibrous red phosphorus, phosphorus chains lie parallel instead of orthogonal, unlike violet phosphorus. Such a structure is depicted below:
Fibrous red phosphorus, similar to red phosphorus, displays activity as a photocatalyst.
See also
White phosphorus
Violet phosphorus
Allotropes of phosphorus
Phosphorus
References
Allotropes | Red phosphorus | [
"Physics",
"Chemistry"
] | 902 | [
"Periodic table",
"Properties of chemical elements",
"Allotropes",
"Materials",
"Matter"
] |
77,581,443 | https://en.wikipedia.org/wiki/Aron%20Walsh | Aron Walsh (born February 28, 1983) is a chemist known for his research in the fields of computational chemistry and materials science.
Early life and education
Walsh received his undergraduate degree in chemistry from Trinity College Dublin. He went on to complete his PhD in computational chemistry at the same institution. His postdoctoral research included a Marie Curie Fellowship at University College London and a fellowship at the National Renewable Energy Laboratory in the United States.
Academic career
Walsh began his academic career as a Royal Society University Research Fellow at the University of Bath, where he also served as a professor of Materials Theory. He holds a faculty position at Imperial College London leading the Materials Design Group.
Research contributions
Walsh's research integrates quantum mechanics with data-driven machine learning and multi-scale modeling approaches.
Awards and honours
Royal Society of Chemistry Harrison-Meldola Memorial Prize (2013)
Marsh Prize for Best Chemistry Publication (2014) by the University of Bath.
Publications and editorial work
Walsh has written or co-written over 500 research articles. Additionally, he serves as an Associate Editor for the Journal of the American Chemical Society (JACS).
References
1983 births
Living people
Alumni of Trinity College Dublin
Computational chemists
Materials scientists and engineers
Academics of Imperial College London
Academics of the University of Bath | Aron Walsh | [
"Chemistry",
"Materials_science",
"Engineering"
] | 253 | [
"Materials science",
"Computational chemists",
"Computational chemistry",
"Theoretical chemists",
"Materials scientists and engineers"
] |
77,582,898 | https://en.wikipedia.org/wiki/Type%20IIA%20supergravity | In supersymmetry, type IIA supergravity is the unique supergravity in ten dimensions with two supercharges of opposite chirality. It was first constructed in 1984 by a dimensional reduction of eleven-dimensional supergravity on a circle. The other supergravities in ten dimensions are type IIB supergravity, which has two supercharges of the same chirality, and type I supergravity, which has a single supercharge. In 1986 a deformation of the theory was discovered which gives mass to one of the fields and is known as massive type IIA supergravity. Type IIA supergravity plays a very important role in string theory as it is the low-energy limit of type IIA string theory.
History
After supergravity was discovered in 1976 with pure 4D supergravity, significant effort was devoted to understanding other possible supergravities that can exist with various numbers of supercharges and in various dimensions. The discovery of eleven-dimensional supergravity in 1978 led to the derivation of many lower dimensional supergravities through dimensional reduction of this theory. Using this technique, type IIA supergravity was first constructed in 1984 by three different groups, by F. Giani and M. Pernici, by I.C.G. Campbell and P. West, and by M. Huq and M. A. Namazie. In 1986 it was noticed by L. Romans that there exists a massive deformation of the theory. Type IIA supergravity has since been extensively used to study the low-energy behaviour of type IIA string theory. The terminology of type IIA, type IIB, and type I was coined by J. Schwarz, originally to refer to the three string theories that were known of in 1982.
Theory
Ten dimensions admits both and supergravity, depending on whether there are one or two supercharges. Since the smallest spinorial representations in ten dimensions are Majorana–Weyl spinors, the supercharges come in two types depending on their chirality, giving three possible supergravity theories. The theory formed using two supercharges of opposite chiralities is denoted by and is known as type IIA supergravity.
This theory contains a single multiplet, known as the ten-dimensional nonchiral multiplet. The fields in this multiplet are , where is the metric corresponding to the graviton, while the next three fields are the 3-, 2-, and 1-form gauge fields, with the 2-form being the Kalb–Ramond field. There is also a Majorana gravitino and a Majorana spinor , both of which decompose into a pair of Majorana–Weyl spinors of opposite chiralities and . Lastly, there a scalar field .
This nonchiral multiplet can be decomposed into the ten-dimensional multiplet , along with four additional fields . In the context of string theory, the bosonic fields in the first multiplet consists of NSNS fields while the bosonic fields are all RR fields. The fermionic fields are meanwhile in the NSR sector.
Algebra
The superalgebra for supersymmetry is given by
where all terms on the right-hand side besides the first one are the central charges allowed by the theory. Here are the spinor components of the Majorana supercharges while is the charge conjugation operator. Since the anticommutator is symmetric, the only matrices allowed on the right-hand side are ones that are symmetric in the spinor indices , . In ten dimensions is symmetric only for modulo , with the chirality matrix behaving as just another matrix, except with no index. Going only up to five-index matrices, since the rest are equivalent up to Poincare duality, yields the set of central charges described by the above algebra.
The various central charges in the algebra correspond to different BPS states allowed by the theory. In particular, the , and correspond to the D0, D2, and D4 branes. The corresponds to the NSNS 1-brane, which is equivalent to the fundamental string, while corresponds to the NS5-brane.
Action
The type IIA supergravity action is given up to four-fermion terms by
Here and where corresponds to a -form gauge field. The 3-form gauge field has a modified field strength tensor with this having a non-standard Bianchi identity of . Meanwhile, , , , and are various fermion bilinears given by
The first line of the action has the Einstein–Hilbert action, the dilaton kinetic term, the 2-form field strength tensor. It also contains the kinetic terms for the gravitino and spinor , described by the Rarita–Schwinger action and Dirac action, respectively. The second line has the kinetic terms for the 1-form and 3-form gauge fields as well as a Chern–Simons term. The last line contains the cubic interaction terms between two fermions and a boson.
Supersymmetry transformations
The supersymmetry variations that leave the action invariant are given up to three-fermion terms by
They are useful for constructing the Killing spinor equations and finding the supersymmetric ground states of the theory since these require that the fermionic variations vanish.
Related theories
Massive type IIA supergravity
Since type IIA supergravity has p-form field strengths of even dimensions, it also admits a nine-form gauge field . But since is a scalar and the free field equation is given by , this scalar must be a constant. Such a field therefore has no propagating degrees of freedom, but does have an energy density associated to it. Working only with the bosonic sector, the ten-form can be included in supergravity by modifying the original action to get massive type IIA supergravity
where is equivalent to the original type IIA supergravity up to the replacement of and . Here is known as the Romans mass and it acts as a Lagrange multiplier for . Often one integrates out this field strength tensor resulting in an action where acts as a mass term for the Kalb–Ramond field.
Unlike in the regular type IIA theory, which has a vanishing scalar potential , massive type IIA has a nonvanishing scalar potential. While the supersymmetry transformations appear to be realised, they are actually formally broken since the theory corresponds to a D8-brane background. A closely related theory is Howe–Lambert–West supergravity which is another massive deformation of type IIA supergravity, but one that can only be described at the level of the equations of motion. It is acquired by a compactification of eleven-dimensional MM theory on a circle.
Relation to 11D supergravity
Compactification of eleven-dimensional supergravity on a circle and keeping only the zero Fourier modes that are independent of the compact coordinates results in type IIA supergravity. For eleven-dimensional supergravity with the graviton, gravitino, and a 3-form gauge field denoted by , then the 11D metric decomposes into the 10D metric, the 1-form, and the dilaton as
Meanwhile, the 11D 3-form decomposes into the 10D 3-form and the 10D 2-form . The ten-dimensional modified field strength tensor directly arises in this compactification from .
Dimensional reduction of the fermions must generally be done in terms of the flat coordinates , where is the 11D vielbein. In that case the 11D Majorana graviton decomposes into the 10D Majorana gravitino and the Majorana fermion , although the exact identification is given by
where this is chosen to make the supersymmetry transformations simpler. The ten-dimensional supersymmetry variations can also be directly acquired from the eleven-dimensional ones by setting .
Relation to type IIA string theory
The low-energy effective field theory of type IIA string theory is given by type IIA supergravity. The fields correspond to the different massless excitations of the string, with the metric, 2-form , and dilaton being NSNS states that are found in all string theories, while the 3-form and 1-form fields correspond to the RR states of type IIA string theory. Corrections to the type IIA supergravity action come in two types, quantum corrections in powers of the string coupling , and curvature corrections in powers of . Such corrections often play an important role in type IIA string phenomenology. The type IIA superstring coupling constant corresponds to the vacuum expectation value of , while the string length is related to the gravitational coupling constant through .
When string theory is compactified to acquire four-dimensional theories, this is often done at the level of the low-energy supergravity. Reduction of type IIA on a Calabi–Yau manifold yields an theory in four dimensions, while reduction on a Calabi–Yau orientifold further breaks the symmetry down to give the phenomenologically viable four-dimensional supergravity. Type IIA supergravity is automatically anomaly free since it is a non-chiral theory.
Notes
References
Supersymmetric quantum field theory
Theories of gravity
String theory | Type IIA supergravity | [
"Physics",
"Astronomy"
] | 1,941 | [
"Astronomical hypotheses",
"Supersymmetric quantum field theory",
"Theoretical physics",
"Theories of gravity",
"String theory",
"Supersymmetry",
"Symmetry"
] |
77,583,575 | https://en.wikipedia.org/wiki/Type%20IIB%20supergravity | In supersymmetry, type IIB supergravity is the unique supergravity in ten dimensions with two supercharges of the same chirality. It was first constructed in 1983 by John Schwarz and independently by Paul Howe and Peter West at the level of its equations of motion. While it does not admit a fully covariant action due to the presence of a self-dual field, it can be described by an action if the self-duality condition is imposed by hand on the resulting equations of motion. The other types of supergravity in ten dimensions are type IIA supergravity, which has two supercharges of opposing chirality, and type I supergravity, which has a single supercharge. The theory plays an important role in modern physics since it is the low-energy limit of type IIB string theory.
History
After supergravity was discovered in 1976, there was a concentrated effort to construct the various possible supergravities that were classified in 1978 by Werner Nahm. He showed that there exist three types of supergravity in ten dimensions, later named type I, type IIA and type IIB. While both type I and type IIA can be realised at the level of the action, type IIB does not admit a covariant action. Instead it was first fully described through its equations of motion, derived in 1983 by John Schwartz, and independently by Paul Howe and Peter West. In 1995 it was realised that one can effectively describe the theory using a pseudo-action where the self-duality condition is imposed as an additional constraint on the equations of motion. The main application of the theory is as the low-energy limit of type IIB strings, and so it plays an important role in string theory, type IIB moduli stabilisation, and the AdS/CFT correspondence.
Theory
Ten-dimensional supergravity admits both and supergravities, which differ by the number of the Majorana–Weyl spinor supercharges that they possess. The type IIB theory has two supercharges of the same chirality, equivalent to a single Weyl supercharge, with it sometimes denoted as the ten-dimensional supergravity. The field content of this theory is given by the ten dimensional chiral supermultiplet . Here is the metric corresponding to the graviton, while are 4-form, 2-form, and 0-form gauge fields. Meanwhile, is the Kalb–Ramond field and is the dilaton. There is also a single left-handed Weyl gravitino , equivalent to two left-handed Majorana–Weyl gravitinos, and a single right-handed Weyl fermion , also equivalent to two right-handed Majorana–Weyl fermions.
Algebra
The superalgebra for ten-dimensional supersymmetry is given by
Here with are the two Majorana–Weyl supercharges of the same chirality. They therefore satisfy the projection relation where is the left-handed chirality projection operator and is the ten-dimensional chirality matrix.
The matrices allowed on the right-hand side are fixed by the fact that they must be representations of the R-symmetry group of the type IIB theory, which only allows for , and trace-free symmetric matrices . Since the anticommutator is symmetric under an exchange of the spinor and indices, the maximally extended superalgebra can only have terms with the same chirality and symmetry property as the anticommutator. The terms are therefore a product of one of the matrices with , where is the charge conjugation operator. In particular, when the spinor matrix is symmetric, it multiplies or while when it is antisymmetric it multiplies . In ten dimensions is symmetric for modulo and antisymmetric for modulo . Since the projection operator is a sum of the identity and a gamma matrix, this means that the symmetric combination works when modulo and the antisymmetric one when modulo . This yields all the central charges found in the superalgebra up to Poincaré duality.
The central charges are each associated to various BPS states that are found in the theory. The central charges correspond to the fundametnal string and the D1 brane, is associated with the D3 brane, while and give three 5-form charges. One is the D5-brane, another the NS5-brane, and the last is associated with the KK monopole.
Self-dual field
For the supergravity multiplet to have an equal number of bosonic and fermionic degrees of freedom, the four-form has to have 35 degrees of freedom. This is achieved when the corresponding field strength tensor is self-dual , eliminating half of the degrees of freedom that would otherwise be found in a 4-form gauge field.
This presents a problem when constructing an action since the kinetic term for the self-dual 5-form field vanishes. The original way around this was to only work at the level of the equations of motion where self-duality is just another equation of motion. While it is possible to formulate a covariant action with the correct degrees of freedom by introducing an auxiliary field and a compensating gauge symmetry, the more common approach is to instead work with a pseudo-action where self-duality is imposed as an additional constraint on the equations of motion. Without this constraint the action cannot be supersymmetric since it does not have an equal number of fermionic and bosonic degrees of freedom. Unlike for example type IIA supergravity, type IIB supergravity cannot be acquired as a dimensional reduction of a theory in higher dimensions.
Pseudo-action
The bosonic part of the pseudo-action for type IIB supergravity is given by
Here and are modified field strength tensors for the 2-form and 4-form gauge fields, with the resulting Bianchi identity for the 5-form being given by . The notation employed for the kinetic terms is where are the regular field strength tensors associated to the gauge fields. Self-duality has to be imposed by hand onto the equations of motion, making this a pseudo-action rather than a regular action.
The first line in the action contains the Einstein–Hilbert action, the dilaton kinetic term, and the Kalb–Ramond field strength tensor . The first term on the second line has the appropriately modified field strength tensors for the three gauge fields, while the last term is a Chern–Simons term. The action is written in the string frame which allows one to equate the fields to type IIB string states. In particular, the first line consists of kinetic terms for the NSNS fields, with these terms being identical to those found in type IIA supergravity. The first integral on the second line meanwhile consists of the kinetic term for the RR fields.
Global symmetry
Type IIB supergravity has a global noncompact symmetry. This can be made explicit by rewriting the action into the Einstein frame and defining the axio-dilaton complex scalar field . Introducing the matrix
and combining the two 3-form field strength tensors into a doublet , the action becomes
This action is manifestly invariant under the transformation which transforms the 3-forms and the axio-dilaton as
Both the metric and the self-dual field strength tensor are invariant under these transformations. The invariance of the 3-form field strength tensors follows from the fact that .
Supersymmetry transformations
The equations of motion acquired from the supergravity action are invariant under the following supersymmetry transformations
Here are the field strength tensors associated with the gauge fields, including all their magnetic duals for , while . Additionally, when is even and when it is odd. The type IIB pseudo-action can also be reformulated in a way that treats all RR fluxes equally in the so-called democratic formulation. Here the action is expressed in terms of all even fluxes up to , with a duality constraint imposed on all of them to get the correct number of degrees of freedom.
Relation to string theory
Type IIB supergravity is the low-energy limit of type IIB string theory. The fields of the supergravity in the string frame are directly related to the different massless states of the string theory. In particular, the metric, Kalb–Ramond field, and dilaton are NSNS fields, while the three p-forms are RR fields. Meanwhile, the gravitational coupling constant is related to the Regge slope through .
The global symmetry of the supergravity is not a symmetry of the full type IIB string theory since it would mix the and fields. This does not happen in the string theory since one of these is an NSNS field and the other an RR field, with these having different physics, such as the former coupling to strings but the latter not. The symmetry is instead broken to the discrete subgroup which is believed to be a symmetry of the full type IIB string theory.
The quantum theory is anomaly free, with the gravitational anomalies cancelling exactly. In string theory the pseudo-action receives much studied corrections that are classified into two types. The first are quantum corrections in terms of the string coupling and the second are string corrections terms of the Regge slope . These corrections play an important role in many moduli stabilisation scenarios.
Dimensional reduction of type IIA and type IIB supergravities necessarily results in the same nine-dimensional theory since only one superalgebra of this type exists in this dimension. This is closely linked to the T-duality between the corresponding string theories.
Notes
References
Supersymmetric quantum field theory
Theories of gravity
String theory | Type IIB supergravity | [
"Physics",
"Astronomy"
] | 2,024 | [
"Astronomical hypotheses",
"Supersymmetric quantum field theory",
"Theoretical physics",
"Theories of gravity",
"String theory",
"Supersymmetry",
"Symmetry"
] |
77,583,596 | https://en.wikipedia.org/wiki/CRC%20Standard%20Mathematical%20Tables | CRC Standard Mathematical Tables (also CRC Standard Mathematical Tables and Formulas or SMTF) is a comprehensive one-volume handbook containing a fundamental working knowledge of mathematics and tables of formulas.
History
The handbook was originally published in 1928 by the Chemical Rubber Company (now CRC Press) as a supplement (Mathematical Tables) to the CRC Handbook of Chemistry and Physics.
Beginning with the 10th edition (1956), it was published as CRC Standard Mathematical Tables and kept this title up to the 29th edition (1991). The 30th edition (1996) was renamed CRC Standard Mathematical Tables and Formulae, with Daniel Ian Zwillinger as the editor-in-chief. The 33rd edition (2018) was renamed CRC Standard Mathematical Tables and Formulas.
Editions
The first edition was published in 1928. Subsequent editions are:
Mathematical Tables from Handbook of Chemistry and Physics
3rd edition (1933)
4th edition (1934)
5th edition (1936)
6th edition (1938)
7th edition (1941)
8th edition (1946, 1947)
9th edition (1952)
CRC Standard Mathematical Tables
10th edition (1956)
11th edition (1957)
12th edition (1959, 1964)
13th edition (1964)
14th edition (1965)
15th edition (1967)
16th edition (1968)
17th edition (1969)
18th edition (1970)
19th edition (1971)
20th edition (1972)
21st edition (1973)
22nd edition (1974)
23rd edition (1975)
24th edition (1976)
25th edition (1979)
26th edition (1981)
27th edition (1985)
28th edition (1990)
29th edition (1991)
CRC Standard Mathematical Tables and Formulae (Daniel Zwillinger, ed.)
30th edition (1996)
31st edition (2003)
32nd edition (2011)
CRC Standard Mathematical Tables and Formulas (Daniel Zwillinger, ed.)
33rd edition (2018)
Editors
Editors-in-chief:
Charles D. Hodgman (14th edition and earlier)
Samuel M. Selby (15th–23rd editions)
William H. Beyer (24th–29th editions)
Daniel Zwillinger (30th–33rd editions)
See also
List of important publications in mathematics
Bronshtein and Semendyayev (BS)
Korn (KK)
Abramowitz and Stegun (AS)
Gradshteyn and Ryzhik (GR)
CRC Concise Encyclopedia of Mathematics
CRC Handbook of Chemistry and Physics
References
External links
Standard Mathematical Tables and Formulae home page (Daniel Zwillinger's website)
Mathematics handbooks
Mathematical tables
CRC Press books | CRC Standard Mathematical Tables | [
"Mathematics"
] | 513 | [
"Mathematical tables"
] |
77,583,924 | https://en.wikipedia.org/wiki/Type%20I%20supergravity | In supersymmetry, type I supergravity is the theory of supergravity in ten dimensions with a single supercharge. It consists of a single supergravity multiplet and a single Yang–Mills multiplet. The full non-abelian action was first derived in 1983 by George Chapline and Nicholas Manton. Classically the theory can admit any gauge group, but a consistent quantum theory resulting in anomaly cancellation only exists if the gauge group is either or . Both these supergravities are realised as the low-energy limits of string theories, in particular of type I string theory and of the two heterotic string theories.
History
Supergravity was much studied during the 1980s as a candidate theory of nature. As part of this it was important to understand the various supergravities that can exist in different dimensions, with the possible supergravities being classified in 1978 by Werner Nahm. Type I supergravity was first written down in 1983, with Eric Bergshoeff, Mees de Roo, Bernard de Wit, and Peter van Nieuwenhuizen describing the abelian theory, and then George Chapline and Nicholas Manton extending this to the full non-abelian theory. An important development was made by Michael Green and John Schwarz in 1984 when they showed that only a handful of these theories are anomaly free, with additional work showing that only and result in a consistent quantum theory. The first case was known at the time to correspond to the low-energy limit of type I superstrings. Heterotic string theories were discovered the next year, with these having a low-energy limit described by type I supergravity with both gauge groups.
Theory
Type I supergravity is the ten-dimensional supergravity with a single Majorana–Weyl spinor supercharge. Its field content consists of the supergravity supermultiplet , together with the Yang–Mills supermultiplet with some associated gauge group. Here is the metric, is the two-form Kalb–Ramond field, is the dilaton, and is a Yang–Mills gauge field. Meanwhile, is the gravitino, is a dilatino, and a gaugino, with all these being Majorana–Weyl spinors. The gravitino and gaugino have the same chirality, while the dilatino has the opposite chirality.
Algebra
The superalgebra for type I supersymmetry is given by
Here is the supercharge with a fixed chirality , where is the relevant projection operator. Meanwhile, is the charge conjugation operator and are the gamma matrices. The right-hand side must have the same chirality as the supercharges and must also be symmetric under an exchange of the spinor indices. The second term is the only central charge that is admissible under these constraints up to Poincare duality. This is because in ten dimensions only with modulo are symmetric matrices. The central charge corresponds to a 5-brane solution in the supergravity which is dual to the fundamental string in heterotic string theory.
Action
The action for type I supergravity in the Einstein frame is given up to four-fermion terms by
Here is the gravitational coupling constant, is the dilaton, and
where is the trace of the Yang–Mills Chern–Simons form given by
The non-abelian field strength tensor corresponding to the gauge field is denote by . The spacetime index gamma-matrices are position-dependent fields . Meanwhile, is the covariant derivative , while and is the spin connection.
Supersymmetry transformations
The supersymmetry transformation rules are given up to three fermion terms by
The supersymmetry parameter is denoted by . These transformation rules are useful for constructing the Killing spinor equations and finding supersymmetric ground states.
Anomaly cancellation
At a classical level the supergravity has an arbitrary gauge group, however not all gauge groups are consistent at the quantum level. The Green–Schwartz anomaly cancellation mechanism is used to show when the gauge, mixed, and gravitational anomalies vanish in hexagonal diagrams. In particular, the only anomaly free type I supergravity theories are ones with gauge groups of , , , and . It was later found that the latter two with abelian factors are inconsistent theories of quantum gravity. The remaining two theories both have ultraviolet completions to string theory, where the corresponding string theories can also be shown to be anomaly free at the string level.
Relation to string theory
Type I supergravity is the low-energy effective field theory of type I string theory and both heterotic string theories. In particular, type I string theory and heterotic string theory reduce to type I supergravity with an gauge group, while heterotic string theory reduces to type I supergravity with an gauge group. There are additional corrections that the supergravity receives in string theory, notably the Chern–Simons term becomes a linear combination of the Yang–Mills Chern–Simons three-form found at tree-level and a Lorentz Chern–Simons three-form . This latter three-form is a higher-derivative correction given by
,
where is the spin connection. To maintain supersymmetry of the action when this term is included, additional higher-derivative corrections must be added to the action up to second order in .
In type I string theory, the gauge coupling constant is related to the ten-dimensional Yang–Mills coupling constant by , while the coupling constant is related to the string length by . Meanwhile, in heterotic string theory the gravitational coupling constant is related to the string length by .
The fields in the Einstein frame are not the same as the fields corresponding to the string states. Instead, one has to transform the action into the various string frames through a Weyl transformation and dilaton redefinition
S-duality between type I string theory and heterotic string theory can be seen at the level of the action since the respective string frame actions are equivalent with the correct field redefinitions. Similarly, Hořava–Witten theory, which describes the duality between heterotic string theory and M-theory, can also be seen at the level of the supergravity since compactification of eleven-dimensional supergravity on , yields supergravity.
Notes
References
Supersymmetric quantum field theory
Theories of gravity
String theory | Type I supergravity | [
"Physics",
"Astronomy"
] | 1,325 | [
"Astronomical hypotheses",
"Supersymmetric quantum field theory",
"Theoretical physics",
"Theories of gravity",
"String theory",
"Supersymmetry",
"Symmetry"
] |
77,585,390 | https://en.wikipedia.org/wiki/NGC%205260 | NGC 5260 is a barred spiral galaxy in the constellation of Hydra. Its velocity with respect to the cosmic microwave background is 6789 ± 21 km/s, which corresponds to a Hubble distance of 100.13 ± 7.02 Mpc (∼327 million light-years). It was discovered by American astronomer Lewis Swift on 6 April 1885.
According to the SIMBAD database, NGC 5260 is a Seyfert II galaxy, i.e. it has a quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.
NGC 5260 forms a physical pair with galaxy ESO 509- G 093, collectively named RR 254, with an optical separation of between them.
Supernovae
Two supernovae have been observed in NGC 5260:
SN 2022jkx (type Ib, mag. 18.819) was discovered by ATLAS on 3 May 2022.
SN 2023dtd (type II, mag. 18.516) was discovered by ATLAS on 20 March 2023.
See also
List of NGC objects (5001–6000)
References
External links
5260
048371
-04-32-050
509-092
13375-2336
Hydra (constellation)
18850406
Discoveries by Lewis Swift
Barred spiral galaxies
Seyfert galaxies | NGC 5260 | [
"Astronomy"
] | 294 | [
"Hydra (constellation)",
"Constellations"
] |
77,585,607 | https://en.wikipedia.org/wiki/Methoxyacrylates | Methoxyacrylates (more precisely β-methoxyacrylates) are a group of organic compounds primarily used as fungicides. They comprise an acrylic acid ester unit that also includes a methoxy group, making them a type of enol ether.
Structure and effect
The methoxyacrylate group is derived from strobilurins. Strobilurins feature a diene unit, which renders them only slightly photostable. In their synthetic analogs, this diene unit is typically replaced by other structural elements, usually aromatic rings. Methoxyacrylates inhibit cytochrome c oxidase, thereby blocking electron transport and the respiratory chain in the mitochondrion of fungi. Specifically, the active ingredients bind to the binding site for the oxidation of ubiquinol. The interruption of the respiratory chain prevents the biosynthesis of adenosine triphosphate, leads to energy deficiency and thus to the death of the fungi. The methoxyacrylate unit is critical to this inhibitory effect, which is why the active substance group is named after it.
Representatives and use
Notable representatives of methoxyacrylates include azoxystrobin and picoxystrobin. Broadly speaking, the term also encompasses compounds lacking a methoxyacrylate unit, such as kresoxim-methyl, which features an oxime ether unit instead. This unit is isosteric with the enol ether unit, allowing the compound to exert a similar effect. Azoxystrobin was the first compound of this group to be approved in 1996, and more than ten compounds are now in commercial use. Additional representatives include pyraclostrobin, trifloxystrobin, fluoxastrobin, enoxastrobin, metominostrobin, coumoxystrobin, dimoxystrobin, fluacrypyrim, and orysastrobin.
Methoxyacrylates are utilized as agricultural fungicides. Their primary advantage is their potent toxicity against a wide range of fungi, coupled with low toxicity in mammals, making them a vital class of active ingredients. Methoxyacrylates hold significant importance in the field of agricultural fungicides, with a substantial market share. In 1999, this group of active ingredients accounted for over 10% of the fungicide market, with sales totaling US$620 million, led by azoxystrobin, which alone generated approximately US$415 million in sales. In 2016, methoxyacrylates continued to dominate the fungicide market, with the top three fungicides by sales value—azoxystrobin, pyraclostrobin, and trifloxystrobin—all belonging to this group.
References
Carboxylate esters
Methyl esters
Fungicides | Methoxyacrylates | [
"Biology"
] | 591 | [
"Fungicides",
"Biocides"
] |
77,585,608 | https://en.wikipedia.org/wiki/4-Hydroxybenzyl%20isothiocyanate | 4-Hydroxybenzyl isothiocyanate is a naturally occurring isothiocyanate. It is formed as a degradation product of sinalbin from white mustard and contributes to the pungent taste of mustard seeds.
Occurrence
4-hydroxybenzyl isothiocyanate occurs as a degradation product of sinalbin or glucosinalbin in white mustard. This compound is broken down as a mustard oil glycoside by myrosinase, releasing the isothiocyanate. The isothiocyanate further decomposes into hydroxybenzyl alcohols with the release of thiocyanates. In the presence of a nitrile-specifier protein, the less toxic 4-hydroxyphenylacetonitrile is formed from the mustard oil glycoside instead. The cabbage butterfly exploits this mechanism to avoid the toxic effects of the isothiocyanate. Similar to other isothiocyanates found in cruciferous vegetables, this compound contributes to the pungent flavor of mustard.
Production
Similar to its natural formation, 4-hydroxybenzyl isothiocyanate can be synthesized by reacting sinalbin with myrosinase.
References
Isothiocyanates
4-Hydroxyphenyl compounds | 4-Hydroxybenzyl isothiocyanate | [
"Chemistry"
] | 268 | [
"Isothiocyanates",
"Functional groups"
] |
77,585,629 | https://en.wikipedia.org/wiki/RTI-5152-12 | RTI-5152-12, or WW-12 (in patent), is a synthetic small-molecule agonist of the atypical chemokine receptor ACKR3 (CXCR7) that was derived from the naturally occurring alkaloid conolidine. RTI-5152-12 has 15-fold improved potency towards ACKR3 relative to conolidine.
ACKR3 is a novel opioid receptor which functions as a broad-spectrum trap or scavenger for endogenous opioid peptides, including enkephalins, dynorphins, and nociceptin. The receptor acts as a negative modulator of the opioid system by decreasing the availability of opioid peptides for their classical receptors like the μ-opioid receptor. Ligands of ACKR3, by competitively displacing endogenous opioid peptides from ACKR3, can potentiate the actions of these endogenous opioids and produce effects like analgesia and anxiolysis in animals.
RTI-5152-12 is being developed as a potential pharmaceutical drug and, as of December 2021, is in the preclinical stage of development for treatment of pain. The chemical structure was not disclosed until a patent was published in June 2022.
See also
LIH383
References
External links
The Good Drug Guide - Conolidine / RTI-5152-12 - David Pearce
Opioid modulators
Opioid peptides
Piperidines
Indoles
Ketones | RTI-5152-12 | [
"Chemistry"
] | 326 | [
"Ketones",
"Functional groups"
] |
77,586,196 | https://en.wikipedia.org/wiki/Central%20America%20Regional%20Security%20Initiative | The Central America Regional Security Initiative (CARSI) is a US foreign security assistance program for Central American countries – Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama – that provides equipment, training, and technical support for law enforcement efforts, and programs intended to strengthen each country's long-term capacity to handle security issues and their underlying conditions. CARSI was initially part of the Mérida Initiative, which included Mexico and Central America, established in 2008 by President George W. Bush. Under Barack Obama, CARSI was created as a standalone program in 2010.
Background
In 2007, President Bush traveled to Mexico and Central America. During the trip, drug trafficking and the rapid rise in crime and violence were the main discussion topics. The openness of the respective governments to addressing these issues led to Bush creating a security assistance package, named the Mérida Initiative. Obama and Congress relaunched the Central American part of the Initiative in 2010 as CARSI.
Objectives and implementation
The US Department of State stated five main goals for CARSI:
Create safe streets for the citizens in the region.
Disrupt the movement of criminals and contraband within and between the nations of Central America.
Support the development of strong, capable and accountable Central American governments.
Re-establish effective state presence and security in communities at risk.
Foster enhanced levels of security and rule of law coordination and cooperation between the nations of the region.
Most of the funding is managed by the Department of State and the US Agency for International Development (USAID). Other agencies and sub-agencies involved in program implementation include the Department of Defense (DOD); the Department of the Treasury; the Department of Homeland Security (DHS); Immigration and Customs Enforcement (ICE); Customs and Border Protection (CBP); the Coast Guard; the Department of Justice (DOJ); the Federal Bureau of Investigation (FBI); the Drug Enforcement Administration (DEA); the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF); and the Office of Overseas Prosecutorial Development, Assistance and Training (OPDAT).
Programs
In the area of law enforcement and counternarcotics, CARSI efforts included equipment and investigative support. In Guatemala, helicopters were provided to allow security forces rapid access to hard-to-reach areas. FBI-led Transnational Anti-Gang (TAG) units were established in several countries. Investigations have been undertaken into money laundering, cash smuggling; and trafficking in drugs, weapons, and people.
Various programs addressed strengthening law enforcement and justice institutions for the long-term. These include: assessing and creating community policing, forensic labs, wiretapping centers, and criminal investigation schools; establishing intelligence-gathering systems; and training and technical assistance for prosecution and court and prison management.
Prevention programs, addressing underlying causes, included providing educational, recreational, and vocational opportunities for at-risk youth. Implementation focused on the local municipal level, with over 120 community outreach centers created.
Funding
In fiscal years 2008 to 2011, the State Department provided $361.5 million in assistance to Central American countries through the Mérida Initiative and CARSI. Through 2012, the largest share of funding was divided between the "northern triangle" countries of Guatemala (22.5%), Honduras (17.3%), and El Salvador (16.3%), followed by Panama (10.4%), Costa Rica (6.9%), Belize (3.9%), Nicaragua (3.9%), and regional initiatives (19.6%); after 2012, the State Department did not make public the distribution breakdown, but reported that the northern triangle continued to receive the majority of funds. For fiscal 2024, the Biden administration requested $341.3 million for CARSI.
Results
As of 2015, little information on the impact of CARSI had been made publicly available. Some evaluations indicated positive results in particular communities. Overall, security indicators at the country level had not shown significant improvements. In 2023, a Congressional Research Service report noted about the broader region: "In the past few years, U.S. assistance efforts in Latin America and the Caribbean have expanded as many countries ... have seen setbacks in long-term development and new challenges have emerged. Socioeconomic conditions began to stagnate in many Latin American and Caribbean countries around 2015 ... These conditions deteriorated sharply in 2020 as the COVID-19 pandemic swept away more than a decade of development gains. Political conditions also have deteriorated as governments in Venezuela and Nicaragua have entrenched authoritarian rule ... These challenges have contributed to political unrest and large-scale migration flows throughout Latin America and the Caribbean."
References
Drug control law | Central America Regional Security Initiative | [
"Chemistry"
] | 956 | [
"Drug control law",
"Regulation of chemicals"
] |
77,586,987 | https://en.wikipedia.org/wiki/Tianyi%20Zheng | Tianyi Zheng is a Chinese-American mathematician specializing in geometric group theory and probability theory, including the theory of random walks and harmonic functions on groups. She is a professor of mathematics at the University of California, San Diego.
Education and career
Zheng was an undergraduate mathematics student at Tsinghua University, graduating in 2008. She completed a Ph.D. in 2013 at Cornell University, with the dissertation Random Walks On Some Classes Of Solvable Groups advised by Laurent Saloff-Coste.
She became a postdoctoral Szegő Assistant Professor at Stanford University from 2013 to 2016 before obtaining a regular-rank faculty position as assistant professor at the University of California, San Diego in 2016.
Recognition
Zheng was named a Sloan Research Fellow in 2019. She was an invited speaker in mathematical analysis at the 2022 (virtual) International Congress of Mathematicians.
In 2024, she was a recipient of the Rollo Davidson Prize, given "for her deep results and resolution of long-standing conjectures on random walks on groups".
References
External links
Home page
Year of birth missing (living people)
Living people
21st-century American mathematicians
21st-century American women mathematicians
21st-century Chinese mathematicians
Chinese women mathematicians
Group theorists
Probability theorists
Mathematical analysts
Tsinghua University alumni
Cornell University alumni
University of California, San Diego faculty
Sloan Research Fellows | Tianyi Zheng | [
"Mathematics"
] | 263 | [
"Mathematical analysis",
"Mathematical analysts"
] |
77,587,434 | https://en.wikipedia.org/wiki/NGC%207110 | NGC 7110 is a barred spiral galaxy in the constellation of Piscis Austrinus. Its velocity with respect to the cosmic microwave background is 5044 ± 20 km/s, which corresponds to a Hubble distance of 74.39 ± 5.22 Mpc (∼243 million light-years). It was discovered by British astronomer John Herschel on 23 September 1834.
One supernova has been observed in NGC 7110: SN 2023hnl (type Ia, mag. 17.831) was discovered by ATLAS on 2 May 2023.
IC 5105 Group
According to A. M. Garcia, NGC 7110 is part of the IC 5105 group (also known as LGG 445). This group of galaxies contains at least 19 members. The other galaxies in the group are: NGC 7057, NGC 7060, NGC 7072, NGC 7075, NGC 7087, NGC 7130, IC 5105, IC 5105A, IC 5128, IC 5139, and eight galaxies in the ESO catalogue.
See also
List of NGC objects (7001–7840)
References
External links
7110
067199
-06-47-012
403-016
F21392-3423
Piscis Austrinus
18340923
Discoveries by John Herschel
Barred spiral galaxies | NGC 7110 | [
"Astronomy"
] | 277 | [
"Piscis Austrinus",
"Constellations"
] |
77,587,995 | https://en.wikipedia.org/wiki/NGC%202642 | NGC 2642 is a barred spiral galaxy in the constellation of Hydra. Its velocity with respect to the cosmic microwave background is 4632 ± 21 km/s, which corresponds to a Hubble distance of 68.32 ± 4.79 Mpc (∼223 million light-years). It was discovered by British astronomer John Herschel on 19 February 1830.
According to the SIMBAD database, NGC 2642 is a Seyfert I galaxy, i.e. it has a quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable.
Supernovae
Three supernovae have been observed in NGC 2642:
SN 2002fj (type IIn, mag. 15.8) was discovered by Libert "Berto" Monard on 12 September 2002.
SN 2008bh (type II, mag. 16.3) was discovered by the Lick Observatory Supernova Search (LOSS) and by The CHilean Automatic Supernova sEarch (CHASE) on 23 March 2008.
SN 2023aaby (type Ic, mag. 17.943) was discovered by ATLAS on 14 December 2023.
See also
List of NGC objects (2001–3000)
References
External links
2642
024395
-01-22-033
08382-0356
Hydra_(constellation)
Astronomical objects discovered in 1830
Discoveries by John Herschel
Barred spiral galaxies
Seyfert galaxies | NGC 2642 | [
"Astronomy"
] | 309 | [
"Hydra (constellation)",
"Constellations"
] |
77,588,855 | https://en.wikipedia.org/wiki/Iodine%20sulfate | Iodine sulfate is an inorganic compound with the formula I2(SO4)3. It appears as light yellow crystals and reacts with water.
Synthesis
Reaction of diiodosyl sulfate and sulfur trioxide:
Iodine sulfate is also produced when elemental , and react.
Physical properties
Iodine sulfate forms light yellow hygroscopic crystals.
Chemical properties
Iodine sulfate is soluble in organic liquids and stable in anhydrous and strongly acidic solvents. In a humid environment, it darkens due to decomposition that releases molecular iodine.
References
Iodine compounds
Sulfates | Iodine sulfate | [
"Chemistry"
] | 117 | [
"Sulfates",
"Salts"
] |
77,588,892 | https://en.wikipedia.org/wiki/NGC%207363 | NGC 7363 is a barred spiral galaxy in the constellation of Pegasus. Its velocity with respect to the cosmic microwave background is 6393 ± 24 km/s, which corresponds to a Hubble distance of 94.29 ± 6.61 Mpc (∼308 million light-years). It was discovered by German astronomer Heinrich d'Arrest on 27 August 1865.
One supernova has been observed in NGC 7363: SN 2023abdq (type II, mag. 18.69) was discovered by the Gaia Photometric Science Alerts on 22 December 2023.
NGC 7331 Group
According to A. M. Garcia, NGC 7363 is part of the five member NGC 7331 group (also known as LGG 459). The other galaxies in the group are: NGC 7320, NGC 7331, UGC 12082, and UGC 12060.
See also
List of NGC objects (7001–7840)
References
External links
7363
069580
+06-49-078
22409+3344
Pegasus (constellation)
Astronomical objects discovered in 1865
Discoveries by Heinrich Louis d'Arrest
Barred spiral galaxies | NGC 7363 | [
"Astronomy"
] | 241 | [
"Pegasus (constellation)",
"Constellations"
] |
77,589,715 | https://en.wikipedia.org/wiki/St%20Paul%27s%20Medal | The St Paul's Medal, established by British urologist Richard Turner-Warwick in 1989, is awarded annually by the British Association of Urological Surgeons (BAUS) for contributions to the surgical field of urology by a person from outside of the United Kingdom. Awardees include Mohamed Ghoneim, Mark Soloway, Anthony J. Costello, Culley C. Carson III, Indy Gill, and Mani Menon.
List of awardees
See also
St Peter's Medal
References
External links
Awards established in 1989
Urology
Medicine awards | St Paul's Medal | [
"Technology"
] | 108 | [
"Science and technology awards",
"Science award stubs",
"Medicine awards"
] |
77,590,024 | https://en.wikipedia.org/wiki/WA93%20experiment | WA93 experiment (Synonym: Light Universal Detector or LUD) was a detector experiment conducted at CERN for studying the correlations between photons and charged particles. It was an experimental program of CERN and part of the research programme SPS. The experiment was majorly conducted by the Indian High-Energy Heavy Ion Physics Team at CERN-SPS. For measurement of the multiplicity and the rapidity and azimuthal distributions of photons in ultra-relativistic heavy ion collisions, Photon Multiplicity Detector was implemented in the experiment. The experiment was led by Indian physicist Y P Viyogi. Hans H. Gutbrod was the spokesperson of the experimental project. The experimental project was approved on 22 November 1990. The experiment was completed on 9 May 2002.
Description
WA93 experiment was a high-energy physics experiment conducted at CERN's Super Proton Synchrotron (SPS). Its primary goal was studying the properties of quark-gluon plasma (QGP), a hypothetical state of matter believed to have existed in the early universe. According to Big Bang theory, the entire universe was filled with quark–gluon plasma before the matter as we know it was created.
In the experiment, heavy ions, such as sulfur and gold at extremely high energies were involved in collisions to create conditions similar to those shortly after the Big Bang.
Components of experimental setup
The major components of the WA93 experimental setup were beam counter, large magnet dipole, Multi Step Avalanche Chambers, Silicon Drift Detector, Photon Multiplicity Detector, Lead-Glass Spectrometer, Streamer-Tube Detectors, Mid-rapidity Calorimeter, Zero-Degree Calorimeter, Trigger System and Charged-Particle Spectrometer.
References
Experiments
Physics experiments
CERN experiments | WA93 experiment | [
"Physics"
] | 368 | [
"Experimental physics",
"Physics experiments"
] |
77,590,592 | https://en.wikipedia.org/wiki/Palam%C3%B3s%20Canyon | The Palamós Canyon, also known as La Fonera Canyon, is an underwater canyon that forms the underwater valley located off the coast of Palamós, in the province of Girona, Catalonia. This underwater canyon is a significant geological feature of the Balearic Sea and plays an important role in the region's marine biodiversity.
Geography
The Palamós Canyon is a prominent submarine canyon located in the Northwestern Mediterranean Sea, off the coast of Catalonia, Spain. It is situated near the town of Palamós, from which it derives its name. The canyon begins at a depth of approximately 200 meters and extends down to depths exceeding 2,000 meters. The Palamós Canyon was formed through a combination of tectonic activity and sedimentary processes. It is part of the larger Catalan margin, which is characterized by its steep slopes and complex geological structures. The canyon plays a significant role in the transfer of sediments from the continental shelf to the deep sea.
Ecological importance
Submarine canyons like Palamós Canyon are known for their high biodiversity and productivity. The unique topography and hydrography of the canyon create habitats for a variety of marine species, including commercially important fish and invertebrates. The canyon also serves as a conduit for organic matter, supporting deep-sea ecosystems. Is the home of a great diversity of marine species. Among the benthic organisms that inhabit the canyon are corals, sponges, and a variety of invertebrates. In addition, it is a passage area for several species of pelagic fish and marine mammals, including dolphins. Dense cold-water corals have recently been discovered on its walls, living at temperatures around . It is like an oasis of biodiversity, for many crustaceans and fish, with numerous species of coral and other associated species. It forms an area very rich in biodiversity, since its rocky walls are the shelter of an immense variety of organisms, some of which, like corals, sponges and gorgonians, are protected and in danger of extinction.
Research and exploration
The Palamós Canyon has been the subject of various scientific studies, particularly in the fields of oceanography and marine biology. Research has shown that the canyon’s sedimentary dynamics are significantly impacted by both natural and anthropogenic factors. Studies have used various methods, including autonomous hydrographic profilers and near-bottom current meters, to monitor sediment transport and water turbidity within the canyon. Research efforts have focused on understanding sediment dynamics, current patterns, and the ecological significance of the canyon. Notably, the CANYONS project deployed multiple moorings equipped with sediment traps and current meters to study the canyon’s sedimentary processes.
Human impact
Human activities, such as fishing and pollution, have impacted the Palamós Canyon. Efforts are being made to mitigate these impacts through sustainable fishing practices and conservation initiatives. Collaborative projects between scientists and local fishing communities aim to preserve the ecological integrity of the canyon.
See also
Blanes Canyon
Catalan Sea
Submarine canyon
References
External links
Submarine canyons
Oceanography | Palamós Canyon | [
"Physics",
"Environmental_science"
] | 609 | [
"Oceanography",
"Hydrology",
"Applied and interdisciplinary physics"
] |
77,591,639 | https://en.wikipedia.org/wiki/1 | 1 (one, unit, unity) is a number, numeral, and glyph. It is the first and smallest positive integer of the infinite sequence of natural numbers. This fundamental property has led to its unique uses in other fields, ranging from science to sports, where it commonly denotes the first, leading, or top thing in a group. 1 is the unit of counting or measurement, a determiner for singular nouns, and a gender-neutral pronoun. Historically, the representation of 1 evolved from ancient Sumerian and Babylonian symbols to the modern Arabic numeral.
In mathematics, 1 is the multiplicative identity, meaning that any number multiplied by 1 equals the same number. 1 is by convention not considered a prime number. In digital technology, 1 represents the "on" state in binary code, the foundation of computing. Philosophically, 1 symbolizes the ultimate reality or source of existence in various traditions.
In mathematics
The number 1 is the first natural number after 0. Each natural number, including 1, is constructed by succession, that is, by adding 1 to the previous natural number. The number 1 is the multiplicative identity of the integers, real numbers, and complex numbers, that is, any number multiplied by 1 remains unchanged (). As a result, the square (), square root (), and any other power of 1 is always equal to 1 itself. 1 is its own factorial (), and 0! is also 1. These are a special case of the empty product. Although 1 meets the naïve definition of a prime number, being evenly divisible only by 1 and itself (also 1), by modern convention it is regarded as neither a prime nor a composite number.
Different mathematical constructions of the natural numbers represent 1 in various ways. In Giuseppe Peano's original formulation of the Peano axioms, a set of postulates to define the natural numbers in a precise and logical way, 1 was treated as the starting point of the sequence of natural numbers. Peano later revised his axioms to begin the sequence with 0. In the Von Neumann cardinal assignment of natural numbers, where each number is defined as a set that contains all numbers before it, 1 is represented as the singleton , a set containing only the element 0.
The unary numeral system, as used in tallying, is an example of a "base-1" number system, since only one mark – the tally itself – is needed. While this is the simplest way to represent the natural numbers, base-1 is rarely used as a practical base for counting due to its difficult readability.
In many mathematical and engineering problems, numeric values are typically normalized to fall within the unit interval ([0,1]), where 1 represents the maximum possible value. For example, by definition 1 is the probability of an event that is absolutely or almost certain to occur. Likewise, vectors are often normalized into unit vectors (i.e., vectors of magnitude one), because these often have more desirable properties. Functions are often normalized by the condition that they have integral one, maximum value one, or square integral one, depending on the application.
1 is the value of Legendre's constant, introduced in 1808 by Adrien-Marie Legendre to express the asymptotic behavior of the prime-counting function. The Weil's conjecture on Tamagawa numbers states that the Tamagawa number , a geometrical measure of a connected linear algebraic group over a global number field, is 1 for all simply connected groups (those that are path-connected with no 'holes').
1 is the most common leading digit in many sets of real-world numerical data. This is a consequence of Benford’s law, which states that the probability for a specific leading digit is . The tendency for real-world numbers to grow exponentially or logarithmically biases the distribution towards smaller leading digits, with 1 occurring approximately 30% of the time.
As a word
One originates from the Old English word an, derived from the Germanic root , from the Proto-Indo-European root *oi-no- (meaning "one, unique"). Linguistically, one is a cardinal number used for counting and expressing the number of items in a collection of things. One is most commonly a determiner used with singular countable nouns, as in one day at a time. The determiner has two senses: numerical one (I have one apple) and singulative one (one day I'll do it). One is also a gender-neutral pronoun used to refer to an unspecified person or to people in general as in one should take care of oneself.
Words that derive their meaning from one include alone, which signifies all one in the sense of being by oneself, none meaning not one, once denoting one time, and atone meaning to become at one with the someone. Combining alone with only (implying one-like) leads to lonely, conveying a sense of solitude. Other common numeral prefixes for the number 1 include uni- (e.g., unicycle, universe, unicorn), sol- (e.g., solo dance), derived from Latin, or mono- (e.g., monorail, monogamy, monopoly) derived from Greek.
Symbols and representation
History
Among the earliest known records of a numeral system, is the Sumerian decimal-sexagesimal system on clay tablets dating from the first half of the third millennium BCE. The Archaic Sumerian numerals for 1 and 60 both consisted of horizontal semi-circular symbols. By , the older Sumerian curviform numerals were replaced with cuneiform symbols, with 1 and 60 both represented by the same symbol . The Sumerian cuneiform system is a direct ancestor to the Eblaite and Assyro-Babylonian Semitic cuneiform decimal systems. Surviving Babylonian documents date mostly from Old Babylonian () and the Seleucid () eras. The Babylonian cuneiform script notation for numbers used the same symbol for 1 and 60 as in the Sumerian system.
The most commonly used glyph in the modern Western world to represent the number 1 is the Arabic numeral, a vertical line, often with a serif at the top and sometimes a short horizontal line at the bottom. It can be traced back to the Brahmic script of ancient India, as represented by Ashoka as a simple vertical line in his Edicts of Ashoka in c. 250 BCE. This script's numeral shapes were transmitted to Europe via the Maghreb and Al-Andalus during the Middle Ages The Arabic numeral, and other glyphs used to represent the number one (e.g., Roman numeral ( ), Chinese numeral ()) are logograms. These symbols directly represent the concept of 'one' without breaking it down into phonetic components.
Modern typefaces
In modern typefaces, the shape of the character for the digit 1 is typically typeset as a lining figure with an ascender, such that the digit is the same height and width as a capital letter. However, in typefaces with text figures (also known as Old style numerals or non-lining figures), the glyph usually is of x-height and designed to follow the rhythm of the lowercase, as, for example, in . In old-style typefaces (e.g., Hoefler Text), the typeface for numeral 1 resembles a small caps version of , featuring parallel serifs at the top and bottom, while the capital retains a full-height form. This is a relic from the Roman numerals system where represents 1. Many older typewriters do not have a dedicated key for the numeral 1, requiring the use of the lowercase letter L or uppercase I as substitutes.
The lower case "" can be considered a swash variant of a lower-case Roman numeral "", often employed for the final of a "lower-case" Roman numeral. It is also possible to find historic examples of the use of j or J as a substitute for the Arabic numeral 1. In German, the serif at the top may be extended into a long upstroke as long as the vertical line. This variation can lead to confusion with the glyph used for seven in other countries and so to provide a visual distinction between the two the digit 7 may be written with a horizontal stroke through the vertical line.
In other fields
In digital technology, data is represented by binary code, i.e., a base-2 numeral system with numbers represented by a sequence of 1s and 0s. Digitised data is represented in physical devices, such as computers, as pulses of electricity through switching devices such as transistors or logic gates where "1" represents the value for "on". As such, the numerical value of true is equal to 1 in many programming languages. In lambda calculus and computability theory, natural numbers are represented by Church encoding as functions, where the Church numeral for 1 is represented by the function applied to an argument once .
In physics, selected physical constants are set to 1 in natural unit systems in order to simplify the form of equations; for example, in Planck units the speed of light equals 1. Dimensionless quantities are also known as 'quantities of dimension one'. In quantum mechanics, the normalization condition for wavefunctions requires the integral of a wavefunction's squared modulus to be equal to 1. In chemistry, hydrogen, the first element of the periodic table and the most abundant element in the known universe, has an atomic number of 1. Group 1 of the periodic table consists of hydrogen and the alkali metals.
In philosophy, the number 1 is commonly regarded as a symbol of unity, often representing God or the universe in monotheistic traditions. The Pythagoreans considered the numbers to be plural and therefore did not classify 1 itself as a number, but as the origin of all numbers. In their number philosophy, where odd numbers were considered male and even numbers female, 1 was considered neutral capable of transforming even numbers to odd and vice versa by addition. The Neopythagorean philosopher Nicomachus of Gerasa's number treatise, as recovered by Boethius in the Latin translation Introduction to Arithmetic, affirmed that one is not a number, but the source of number. In the philosophy of Plotinus (and that of other neoplatonists), 'The One' is the ultimate reality and source of all existence. Philo of Alexandria (20 BC – AD 50) regarded the number one as God's number, and the basis for all numbers.
See also
−1
References
Sources
.
Integers | 1 | [
"Mathematics"
] | 2,229 | [
"Elementary mathematics",
"Integers",
"Mathematical objects",
"Numbers"
] |
77,592,769 | https://en.wikipedia.org/wiki/NGC%203524 | NGC 3524 is a lenticular galaxy in the constellation of Leo. Its velocity with respect to the cosmic microwave background is 1709 ± 25 km/s, which corresponds to a Hubble distance of 25.21 ± 1.80 Mpc (∼82.2 million light-years). It was discovered by German-British astronomer William Herschel on 11 March 1784.
One supernova has been observed in NGC 3524: SN 2024inv (type Ia, mag. 18.3072) was discovered by Automatic Learning for the Rapid Classification of Events (ALeRCE) on 10 May 2024. This supernova got as bright as magnitude 12.1, making it the second-brightest observed in the year 2024.
See also
List of NGC objects (3001–4000)
References
External links
3524
033604
+02-28-050
06158
Leo (constellation)
17840311
Discoveries by William Herschel
Lenticular galaxies | NGC 3524 | [
"Astronomy"
] | 196 | [
"Leo (constellation)",
"Constellations"
] |
77,592,937 | https://en.wikipedia.org/wiki/List%20of%20Finnish%20regions%20by%20life%20expectancy |
Statistics Finland
Average values for 3-year periods. By default the table is sorted by 2019–2021.
Data source: Statistics Finland
Maps of division of Finland into regions and NUTS-2 regions:
Eurostat (2019—2022)
By default, the table is sorted by 2022.
Data source: Eurostat
Global Data Lab (2019–2022)
Data source: Global Data Lab
Charts
See also
List of countries by life expectancy
List of European countries by life expectancy
Regions of Finland
Demographics of Finland
References
Health in Finland
Demographics of Finland
Finland, life expectancy
Finland
Regions by life expectancy
Finland | List of Finnish regions by life expectancy | [
"Biology"
] | 123 | [
"Senescence",
"Life expectancy"
] |
77,593,139 | https://en.wikipedia.org/wiki/Throttleable%20Liquid%20Propulsion%20Demonstrator | Throttleable Liquid Propulsion Demonstrator (TLPD) is a prototype liquid-propellant rocket engine being developed by ESA.
It uses storable propellant: hydrogen peroxide and ethanol.
The engine has a nominal thrust of 5 kN, and using a pintle injector, the thrust can be varied between 20% and 110%.
The development program is part of ESA's Future Launchers Preparatory Program.
Test firings were done in 2024.
References
Rocket engines using hydrogen peroxide propellant
European Space Agency
Prototypes | Throttleable Liquid Propulsion Demonstrator | [
"Astronomy"
] | 110 | [
"Rocketry stubs",
"Astronomy stubs"
] |
77,593,465 | https://en.wikipedia.org/wiki/NGC%205939 | NGC 5939 is a spiral galaxy in the constellation of Ursa Minor. Its velocity with respect to the cosmic microwave background is 6684 ± 4 km/s, which corresponds to a Hubble distance of 98.59 ± 6.90 Mpc (∼322 million light-years). It was discovered by American astronomer Lewis Swift on 11 July 1883.
Supernovae
Three supernovae have been observed in NGC 5939:
SN 2004ax (type Ib/c, mag. 17.7) was discovered by the Lick Observatory Supernova Search (LOSS) on 21 March 2004. The spectrum indicated this might be a calcium-rich supernova.
SN 2019gss (type II-P, mag. 19.28) was discovered by the Zwicky Transient Facility on 30 may 2019.
SN 2023gps (type Ia, mag. 20) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 23 April 2023.
NGC 5939 Group
NGC 5939 is part of a trio of galaxies: The other two galaxies in the group are IC 1129 and UGC 9896.
See also
List of NGC objects (5001–6000)
References
External links
5939
055022
+12-15-007
09854
15244+6854
Ursa Minor
18830711
Discoveries by Lewis Swift
Spiral galaxies | NGC 5939 | [
"Astronomy"
] | 283 | [
"Ursa Minor",
"Constellations"
] |
77,593,855 | https://en.wikipedia.org/wiki/Glovadalen | Glovadalen (developmental code name UCB-0022) is a dopamine D1 receptor positive allosteric modulator which is under development for the treatment of Parkinson's disease. It has been found to potentiate the capacity of dopamine to activate the D1 receptor by 10-fold in vitro with no actions on other dopamine receptors. As of May 2024, glovadalen is in phase 2 clinical trials for this indication. The drug is under development by UCB Biopharma. It is described as an orally active, centrally penetrant small molecule.
See also
Mevidalen
References
Alcohols
Chloroarenes
D1-receptor agonists
Experimental drugs
Indazoles
Isoquinolines
Ketones | Glovadalen | [
"Chemistry"
] | 156 | [
"Ketones",
"Functional groups"
] |
77,593,873 | https://en.wikipedia.org/wiki/NGC%202804 | NGC 2804 is a lenticular galaxy in the constellation of Cancer. Its velocity with respect to the cosmic microwave background is 8580 ± 20 km/s, which corresponds to a Hubble distance of 126.55 ± 8.86 Mpc (∼413 million light-years). It was discovered by British astronomer John Herschel on 24 February 1827. This galaxy was also observed by the French astronomer Stéphane Javelle on 9 April 1896, and was later added to the Index Catalogue as IC 2455.
According to the SIMBAD database, NGC 2804 is a LINER galaxy, i.e. a galaxy whose nucleus has an emission spectrum characterized by broad lines of weakly ionized atoms.
One supernova has been observed in NGC 2804: SN 2023ftr (type Ia, mag. 18.51) was discovered by the Zwicky Transient Facility on 16 April 2023.
See also
List of NGC objects (2001–3000)
References
External links
IC objects
2804
026196
+03-24-028
04901
Cancer (constellation)
18270224
Discoveries by John Herschel
Lenticular galaxies
LINER galaxies | NGC 2804 | [
"Astronomy"
] | 233 | [
"Cancer (constellation)",
"Constellations"
] |
77,594,024 | https://en.wikipedia.org/wiki/AR%20Lacertae | AR Lacertae is a frequently-studied triple star system in the northern constellation of Lacerta, abbreviated AR Lac. This variable star system is the prototype for "detached systems of the AR Lacertae type". It is dimly visible to the naked eye with a combined peak apparent visual magnitude of 6.08. Based on parallax measurements, AR Lac is located at a distance of 138.6 light years from the Sun. It is drifting closer with a heliocentric radial velocity of −34 km/s.
Observation history
The variability of this binary system was discovered by H. R. Leavitt at Harvard College Observatory, and announced in August 1907 by E. C. Pickering. Due to an orbital period of nearly two days, the eclipsing binary nature of this system was not recognized until 1929 by L. G. Jacchia. W. E. Harper derived orbital elements in 1933. It has an orbital period of 1.98 days and a brightness variation of 0.06 in visual magnitude.
In 1934, A. B. Wyse published spectral classes of K0 and G5 for the components. The K0 star displayed sharp emission lines of singly ionized calcium. The primary minimum is caused by the larger K0 component eclipsing the hotter G5 star, while the secondary eclipse is an annular eclipse of the K0 component by the smaller companion. The stars displayed periodic light variations indicating ellipticity and reflection. The K0 star also showed evidence of significant limb darkening.
In 1946, F. B. Wood reported the intrinsic variability of the hotter component. This variation only disappeared when the smaller star was being eclipsed. The following year, G. E. Kron hypothesized that this variation was due to the presence of huge light and dark patches on the star. To explain the light variations, these had to cover about 20% of the total visible surface, and they must form, move, and later dissolve. The variation was modulated by the rotation period of the star.
By 1972, AR Lac had been identified as an RS Canum Venaticorum variable (RS CVn), consisting of two subgiant stars in a detached binary system. It was found to be a source for radio emission in 1973. This emission varied over time and the system displayed flare activity. The system was detected as an X-ray source by EXOSAT in 1987. The X-ray source with a temperature of dropped to a minimum during the primary eclipse, indicating it originated on the hotter star. In contrast, X-ray emission from plasma was not eclipsed, indicating a source larger than the two stars.
Properties
This is a close, double-lined spectroscopic binary star system, which means the spectra of both components are visible and overlap. They have an essentially circular orbit with a period of 1.98395 days and a separation of 8.9 times the radius of the Sun. The orbital plane is inclined at an angle of 90° to the plane of the sky, which is why two eclipses are visible every orbit. As with other RS CVn systems, their rotation periods are tidally locked to their orbital period. The cooler component is the larger and more massive star, which is consistent with its evolutionary state. There is some evidence of extended matter around this star.
Both components display star spots with an activity cycle of about 17 years. Variation in the orbital period of this system has been reported since 1998, which shows a cyclical oscillation over a period of 50.93 years, and a long-term decrease of a day every 470 million years. This orbital variation may be the result of magnetic activity of the two stars. Stellar flares radiate at a temperature of and expand to 2% of the stellar surface.
In 2022, a co-moving companion to this system was announced, making this a triple star system. It was discovered by the Backyard Worlds: Planet 9 citizen science project. Designated WDJ220838.73+454434.04, this companion is a white dwarf at an angular separation of from the binary pair. At the distance of AR Lac, this is equivalent to a projected separation of about . It has a mass of and a radius of . The companion has an estimated age of 5.75 Gyr and has been steadily cooling for about the last 1.62 Gyr. As a main sequence star, it had a mass of . At the estimated separation, a circular orbit of this companion around the inner binary would have an orbital period of approximately 16,000 years.
References
G-type subgiants
K-type subgiants
White dwarfs
Flare stars
RS Canum Venaticorum variables
Spectroscopic binaries
Triple star systems
Lacerta
Bright Star Catalogue objects
Durchmusterung objects
Henry Draper Catalogue objects
Objects with variable star designations | AR Lacertae | [
"Astronomy"
] | 989 | [
"Lacerta",
"Constellations"
] |
77,594,607 | https://en.wikipedia.org/wiki/MRZ-9547 | MRZ-9547, also known as (R)-phenylpiracetam, (R)-phenotropil, or (R)-fonturacetam, is a selective dopamine reuptake inhibitor ( = 14.5μM) that was developed by Merz Pharma. It is the (R)-enantiomer of the racetam and nootropic phenylpiracetam (phenotropil; fonturacetam).
The drug was under development for the treatment of fatigue associated with Parkinson's disease and was in phase 1 clinical trials for this indication in June 2014. However, no recent development has been reported as of November 2017. There was also interest in MRZ-9547 for treatment of fatigue in people with depression and other conditions, but this was not pursued.
Similarly to other dopamine reuptake inhibitors and related agents, MRZ-9547 has been found to have pro-motivational effects in animals and to reverse motivational deficits induced by the dopamine depleting agent tetrabenazine.
The drug, as the enantiopure (R)-enantiomer of phenylpiracetam, was first described in the scientific literature by 2014.
See also
Armesocarb
CT-005404
PRX-14040
List of Russian drugs
References
Abandoned drugs
Acetamides
Dopamine reuptake inhibitors
Enantiopure drugs
Nicotinic agonists
Phenyl compounds
Pro-motivational agents
Racetams | MRZ-9547 | [
"Chemistry"
] | 328 | [
"Stereochemistry",
"Drug safety",
"Enantiopure drugs",
"Abandoned drugs"
] |
77,594,614 | https://en.wikipedia.org/wiki/NGC%20958 | NGC 958 is a barred spiral galaxy in the constellation of Cetus. Its velocity with respect to the cosmic microwave background is 5505 ± 17 km/s, which corresponds to a Hubble distance of 81.20 ± 5.69 Mpc (∼265 million light-years). However, 19 non-redshift measurements give a distance of 58.93 ± 12.91 Mpc (∼192 million light-years). The galaxy was discovered by German-British astronomer William Herschel on 20 September 1784.
The SIMBAD database lists NGC 958 as a Seyfert II Galaxy, i.e. it has a quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, the host galaxy is clearly detectable. The NASA/IPAC Extragalactic Database (NED) lists NGC 958 as a luminous infrared galaxy (LIRG).
Supernovae
Three supernovae have been observed in NGC 958:
SN 2005A (type Ia, mag. 17.1) was discovered by the Lick Observatory Supernova Search (LOSS) on 5 January 2005.
SN 2022ao (type Ic, mag. 18) was discovered by ATLAS on 5 January 2022.
SN 2022acbu (type II, mag. 20.34) was discovered by the Zwicky Transient Facility on 30 November 2022.
See also
List of NGC objects (1–1000)
References
External links
958
009560
-01-07-019
02281-0309
Cetus
17840920
Discoveries by William Herschel
Barred spiral galaxies
Seyfert galaxies
Luminous infrared galaxies | NGC 958 | [
"Astronomy"
] | 351 | [
"Cetus",
"Constellations"
] |
74,607,085 | https://en.wikipedia.org/wiki/Conley%27s%20fundamental%20theorem%20of%20dynamical%20systems | Conley's fundamental theorem of dynamical systems or Conley's decomposition theorem states that every flow of a dynamical system with compact phase portrait admits a decomposition into a chain-recurrent part and a gradient-like flow part. Due to the concise yet complete description of many dynamical systems, Conley's theorem is also known as the fundamental theorem of dynamical systems. Conley's fundamental theorem has been extended to systems with non-compact phase portraits and also to hybrid dynamical systems.
Complete Lyapunov functions
Conley's decomposition is characterized by a function known as complete Lyapunov function. Unlike traditional Lyapunov functions that are used to assert the stability of an equilibrium point (or a fixed point) and can be defined only on the basin of attraction of the corresponding attractor, complete Lyapunov functions must be defined on the whole phase-portrait.
In the particular case of an autonomous differential equation defined on a compact set X, a complete Lyapunov function V from X to R is a real-valued function on X satisfying:
V is non-increasing along all solutions of the differential equation, and
V is constant on the isolated invariant sets.
Conley's theorem states that a continuous complete Lyapunov function exists for any differential equation on a compact metric space. Similar result hold for discrete-time dynamical systems.
See also
Conley index theory
References
Dynamical systems
Differential topology
Topological dynamics | Conley's fundamental theorem of dynamical systems | [
"Mathematics"
] | 299 | [
"Theorems in dynamical systems",
"Topology",
"Differential topology",
"Mathematical problems",
"Mathematical theorems",
"Topological dynamics",
"Dynamical systems"
] |
74,607,395 | https://en.wikipedia.org/wiki/J%C3%A1n%20Min%C3%A1%C4%8D | Ján Mináč (born 15 June 1953) is a Slovak-Canadian mathematician who is a professor of mathematics at The University of Western Ontario. His research interests include Galois groups, Galois cohomology, quadratic forms, and nonlinear dynamics.
Early life and education
Mináč received his bachelor's degree and his master's level RNDr. degree from Comenius University, Czechoslovakia in 1976 and 1977 respectively. He then earned his Ph.D. in 1986 from Queen’s University in Canada under the supervision of Paulo Ribenboim. The title of his thesis is "Galois Groups, Order Spaces, and Valuations".
His brother Matej Mináč is a film director.
Career
Mináč was a member of Mathematical Sciences Research Institute at Berkeley from 1986 to 1987 and then an NSF Postdoctoral Fellow at the University of California at Berkeley from 1987 to 1989. Afterward, he joined the University of Western Ontario as an assistant professor in 1989. He became an associate professor in 1991 and a full professor in 2003.
Research
Mináč and Nguyễn Duy Tân formulated the Mináč-Tân conjectures on the vanishing of Massey products over fields and the kernel unipotent conjecture. He has also worked on Galois theory and quadratic forms, Galois Demushkin groups, mild pro-2-groups, Galois modules, small quotients of Absolute Galois groups, ghosts in group cohomology, Koszulity properties of Galois cohomology, and Zassenhaus filtrations.
Mináč has also worked on non-linear dynamics in networks and its applications to computational neuroscience.
Awards
Mináč received the Distinguished Research Professor Award at Western University during the years 2004-2005 and 2020-2021. In 2019, he became a Fellow of the Canadian Mathematical Society. During the year 2022-2023, he was a fellow at the Western Academy for Advanced Research. In 2013 he received an Excellence in Teaching Award from the Canadian Mathematical Society. Mináč also received multiple teaching awards at the University of Western Ontario.
References
External links
Website at UWO
1953 births
Living people
Algebraists
Number theorists
Czechoslovak mathematicians
Slovak mathematicians
Queen's University at Kingston alumni
20th-century Canadian mathematicians
21st-century Canadian mathematicians
Academic staff of the University of Western Ontario
Fellows of the Canadian Mathematical Society | Ján Mináč | [
"Mathematics"
] | 465 | [
"Algebra",
"Number theorists",
"Number theory",
"Algebraists"
] |
74,608,100 | https://en.wikipedia.org/wiki/Compound%20internal%20combustion%20engine | A compound internal combustion engine is a type of internal combustion engine (ICE) where gasses of combustion are expanded in two or more stages. A typical arrangement for a compound ICE is that the fuel/air is first combusted and expanded in one of two alternating 4-stroke combustion high-pressure (HP) cylinders, then having given up heat and losing pressure, it exhausts directly into a larger-volume low-pressure (LP) cylinder, where it is re-expanded extracting more work from it.
The crankshaft is arranged so the two high-pressure cylinders have synchronized reciprocating motion, while the low-pressure cylinder throw is positioned at a 180-degree phase difference from the high-pressure throws causing opposing reciprocating motion between the high-pressure and low-pressure cylinders.
History
Compound ICEs have been around for nearly as long as standard ICEs with the first patent being issued to Nicolaus Otto's Deutz company in 1879. This design was likely created by then Deutz employee Gottlieb Daimler.
Other designs for compound ICEs were patented by well known engine designers Rudolf Diesel in 1892 and James Atkinson in 1903.
The Eisenhuth Horseless Vehicle Company produced a series of automobiles with compound ICEs from 1900 to 1908.
The engines in these vehicles ranged from 2 cylinders (1908 model) to 6 cylinders (1907 model).
In 2000 the design was "re-patented" as the five-stroke engine by Gerhard Schmitz. This design was prototyped by British engineering company Ilmor.
Compound ICE patents
Deutz 1879
Forest-Gallice 1888
Connelly 1888
Diesel 1892
Bales 1897
Atkinson 1903
Babled 1903
Butler 1904
Eisenhuth (multiple) 1904–1907
Abbot 1910
Schmitz 2000
See also
Atkinson cycle
Four-stroke engine
Free piston engine
History of the internal combustion engine
Compound steam engine
Turbo-compound engine
References
Internal combustion engine | Compound internal combustion engine | [
"Technology",
"Engineering"
] | 388 | [
"Internal combustion engine",
"Combustion engineering",
"Engines"
] |
74,608,230 | https://en.wikipedia.org/wiki/Yugoslavia%20and%20weapons%20of%20mass%20destruction | The Socialist Federal Republic of Yugoslavia began its own nuclear weapons program in the early 1950s, amid rising tensions with the Soviet Union during the Informbiro period. Yugoslavian leader Josip Broz Tito decided that the development of nuclear technology was in the country's best interest as deterrence from a possible invasion and in order to protect the country's sovereignty.
Nuclear weapons
To protect Yugoslavia's national sovereignty and gain international status, the regime of Josip Broz Tito began a nuclear weapons program in the early 1950s. Yugoslavia would later sign the Non-Proliferation Treaty, which caused the program to shut down. Another nuclear weapons program was started after India tested their nuclear weapons on May 18, 1974. This program would eventually shut down in 1987, but Yugoslavia (and eventually the Republic of Serbia) kept high grade enriched uranium until 2010, where they then gave their uranium to the Russian Federation.
Chemical weapons
Before the Yugoslavian breakup and the Yugoslav Wars, the Yugoslavian government was able to develop and store several different types of chemical weapons such as mustard gas, sarin agent and blister agents. Mustard gas was prepared and installed at the Prva Iski factory in the town of Baric.
Missile program
The Yugoslavian government allegedly worked with Libya and Iraq to develop missiles, cruise missiles and anti-naval/land attack missiles capable of carrying weapons of mass destruction and conventional warheads. Serbia is currently the only former Yugoslav member with a missile program.
Alleged use in the Yugoslav Wars
During the Yugoslav Wars, the Yugoslav Army (Federal Republic of Yugoslavia) allegedly used chemical weapons in combat against Bosnian and Croat separatists. Chemical weapons were not confirmed to have been used in the Yugoslav wars by either sides.
See also
Armijska Ratna Komanda D-0, a Yugoslav nuclear bunker
References
Weapons of Yugoslavia
Nuclear weapons
Chemical weapons
Weapons of mass destruction by country | Yugoslavia and weapons of mass destruction | [
"Chemistry",
"Biology"
] | 379 | [
"Biochemistry",
"Chemical accident",
"Chemical weapons"
] |
74,608,356 | https://en.wikipedia.org/wiki/Xenosome | A xenosome is a bacterium that lives in the body of some marine protozoans. It primarily refers to bacterial invaders of the cytoplasm of a single genus of marine scuticociliates. They are found in ciliates, sometimes with a methanogenic role inside anaerobic ciliates.
In 1985, researcher John Corliss proposed to expand the definition of the term to include all DNA-containing, membrane-bounded bodies or organelles—prokaryotic or eukaryotic in original nature—found within the cytoplasm or nucleus of eukaryotic cells of any or all kinds, regardless of whether the occupation was temporary or permanent.
References
Biological interactions
Bacteria | Xenosome | [
"Biology"
] | 148 | [
"Behavior",
"Biological interactions",
"Prokaryotes",
"nan",
"Bacteria",
"Ethology",
"Microorganisms"
] |
74,608,764 | https://en.wikipedia.org/wiki/JHU-083 | JHU-083 is an experimental drug which acts as a glutaminase inhibitor. It is a prodrug which is cleaved in vivo to the active form 6-diazo-5-oxo-L-norleucine. It has been researched for the treatment of various neurological conditions such as depression, Alzheimer's disease, and cerebral malaria, as well as multiple sclerosis, atherosclerosis, hepatitis, and some forms of cancer in which it was found to target senescent cells.
References
Enzyme inhibitors
Experimental psychiatric drugs
Diazo compounds
Carboxamides
Secondary amines
Ethyl esters
Ketones
Dipeptides | JHU-083 | [
"Chemistry"
] | 138 | [
"Ketones",
"Functional groups"
] |
74,609,099 | https://en.wikipedia.org/wiki/Longform.org | Longform was an American media company founded in Brooklyn, New York City, in April 2010 by journalists Max Linsky and Aaron Lammer. It operated a longform article recommendation service until January 2022, and hosted an interview podcast with journalists talking about their craft until June 2024.
Podcast
The Longform Podcast, hosted by Linsky and Lammer, along with Evan Ratliff, was launched in 2012 in a makeshift studio at the offices of The Atavist Magazine. It consisted of interviews with journalists talking about their craft. Its 585 episodes were published weekly, with the hosts alternating. Each episode interviewed one journalist, sometimes discussing a singular story they'd written and other times their entire oeuvre. It joined the Vox Media Podcast Network in August 2021. It published its last episode in June 2024, at which time The New York Times wrote that it had become "required listening for aspiring and early-career writers who were eager to learn about how the people they looked up to — from veterans of legacy publications to bloggers at new media start-ups — made it to where they were." Owen Lewis, writing for Defector, praised Linsky's "knack for asking unflinching and unexpected questions in a style that comes off as more curious than intrusive". Nicholas Quah wrote for Vulture, "What Longform has created is a historical record of American nonfiction that's so monumental it should really be housed at a university somewhere." He asked various journalists for their favorite episodes, which included one where Linsky interviewed writer Sam Fragoso while accidentally high on edibles.
Episodes
Article recommendation service
Longform operated a longform article recommendation service from its founding until January 2022. Its referral sources included the dating website OkCupid, where people shared their love of the site. From 2014 to 2017, it maintained an app for readers to browse its picks.
References
External links
American websites
2010 establishments in New York City
American podcasts
Interview podcasts
Works about journalism
Works about journalists
Recommender systems
Internet properties established in 2010
Vox Media | Longform.org | [
"Technology"
] | 422 | [
"Information systems",
"Recommender systems"
] |
74,609,356 | https://en.wikipedia.org/wiki/Force%20control | Force control is the control of the force with which a machine or the manipulator of a robot acts on an object or its environment. By controlling the contact force, damage to the machine as well as to the objects to be processed and injuries when handling people can be prevented. In manufacturing tasks, it can compensate for errors and reduce wear by maintaining a uniform contact force. Force control achieves more consistent results than position control, which is also used in machine control. Force control can be used as an alternative to the usual motion control, but is usually used in a complementary way, in the form of hybrid control concepts. The acting force for control is usually measured via force transducers or estimated via the motor current.
Force control has been the subject of research for almost three decades and is increasingly opening up further areas of application thanks to advances in sensor and actuator technology and new control concepts. Force control is particularly suitable for contact tasks that serve to mechanically process workpieces, but it is also used in telemedicine, service robot and the scanning of surfaces.
For force measurement, force sensors exist that can measure forces and torques in all three spatial directions. Alternatively, the forces can also be estimated without sensors, e.g. on the basis of the motor currents. Indirect force control by modeling the robot as a mechanical resistance (impedance) and direct force control in parallel or hybrid concepts are used as control concepts. Adaptive approaches, fuzzy controllers and machine learning for force control are currently the subject of research.
General
Controlling the contact force between a manipulator and its environment is an increasingly important task in the environment of mechanical manufacturing, as well as industrial and service robot. One motivation for the use of force control is safety for man and machine. For various reasons, movements of the robot or machine parts may be blocked by obstacles while the program is running. In service robot these can be moving objects or people, in industrial robotics problems can occur with cooperating robots, changing work environments or an inaccurate environmental model. If the trajectory is misaligned in classical motion control and thus it is not possible to approach the programmed robot pose(s), the motion control will increase the manipulated variable - usually the motor current - in order to correct the position error. The increase of the manipulated variable can have the following effects:
The obstacle is removed or damaged/destroyed.
The machine is damaged or destroyed.
The manipulated variable limits are exceeded and the robot controller switches off.
A force control system can prevent this by regulating the maximum force of the machine in these cases, thus avoiding damage or making collisions detectable at an early stage.
In mechanical manufacturing tasks, unevenness of the workpiece often leads to problems with motion control. As can be seen in the adjacent figure, surface unevenness causes the tool to penetrate too far into the surface during position control (red) or lose contact with the workpiece during position control (red) . This results, for example, in an alternating force effect on the workpiece and tool during grinding and polishing. Force control (green) is useful here, as it ensures uniform material removal through constant contact with the workpiece.
Application
In force control, a basic distinction can be made between applications with pronounced contact and applications with potential contact. We speak of pronounced contact when the contact of the machine with the environment or the workpiece is a central component of the task and is explicitly controlled. This includes, above all, tasks of mechanical deformation and surface machining. In tasks with potential contact, the process function variable is the positioning of the machine or its parts. Larger contact forces between machine and environment occur due to dynamic environment or inaccurate environment model. In this case, the machine should yield to the environment and avoid large contact forces.
The main applications of force control today are mechanical manufacturing operations. This means in particular manufacturing tasks such as grinding, polishing and deburring as well as force-controlled processes such as controlled joining, bending and pressing of bolts into prefabricated bores. Another common use of force control is scanning unknown surfaces. Here, force control is used to set a constant contact pressure in the normal direction of the surface and the scanning head is moved in the surface direction via position control. The surface can then be described in Cartesian coordinates via direct kinematics.
Other applications of force control with potential contact can be found in medical technology and cooperating robots. Robots used in telemedicine, i.e. robot-assisted medical operations, can avoid injuries more effectively via force control. In addition, direct feedback of the measured contact forces to the operator by means of a force feedback control device is of great interest here. Possible applications for this extend to internet-based teleoperations.
In principle, force control is also useful wherever machines and robots cooperate with each other or with humans, as well as in environments where the environment is not described exactly or is dynamic and cannot be described exactly. Here, force control helps to deal with obstacles and deviations in the environmental model and to avoid damage.
History
The first important work on force control was published in 1980 by John Kenneth Salisbury at Stanford University. In it, he describes a method for active stiffness control, a simple form of impedance control. However, the method does not yet allow a combination with motion control, but here force control is performed in all spatial directions. The position of the surface must therefore be known. Because of the lower performance of robot controllers of that time, force control could only be performed on mainframe computers. Thus, a controller cycle of ≈100 ms was achieved.
In 1981, Raibert and Craig presented a paper on hybrid force/position control which is still important today. In this paper, they describe a method in which a matrix (separation matrix) is used to explicitly specify for all spatial directions whether motion or force control is to be used. Raibert and Craig merely sketch the controller concepts and assume them to be feasible.
In 1989, Koivo presented an extended exposition of the concepts of Raibert and Craig. Precise knowledge of the surface position is still necessary here, which still does not allow for the typical tasks of force control today, such as scanning surfaces.
Force control has been the subject of intense research over the past two decades and has made great strides with the advancement of sensor technology and control algorithms. For some years now, the major automation technology manufacturers have been offering software and hardware packages for their controllers to allow force control. Modern machine controllers are capable of force control in one spatial direction in real time computing with a cycle time of less than 10 ms.
Force measurement
To close the force control loop in the sense of a closed-loop control, the instantaneous value of the contact force must be known. The contact force can either be measured directly or estimated.
Direct force measurement
The trivial approach to force control is the direct measurement of the occurring contact forces via force/torque sensors at the end effector of the machine or at the wrist of the industrial robot. Force/torque sensors measure the occurring forces by measuring the deformation at the sensor. The most common way to measure deformation is by means of strain gauges.
In addition to the widely used strain gauges made of variable electrical resistances, there are also other versions that use piezoelectric, optical or capacitive principles for measurement. In practice, however, they are only used for special applications. Capacitive strain gages, for example, can also be used in the high-temperature range above 1000 °C.
Strain gages are designed to have as linear a relationship as possible between strain and electrical resistance within the working space. In addition, several possibilities exist to reduce measurement errors and interference. To exclude temperature influences and increase measurement reliability, two strain gauges can be arranged in a complementary manner.
Modern force/torque sensors measure both forces and torques in all three spatial directions and are available with almost any value range. The accuracy is usually in the per mil range of the maximum measured value. The sampling rates of the sensors are in the range of about 1 kHz. An extension of the 6-axis force/torque sensors are 12- and 18-axis sensors which, in addition to the six force or torque components, are also capable of measuring six velocity and acceleration components each.
Six-axis force/torque sensor
In modern applications, so-called six-axis force/torque sensors are frequently used. These are mounted between the robot hand and the end effector and can record both forces and torques in all three spatial directions. For this purpose, they are equipped with six or more strain gauges (possibly strain measurement bridges) that record deformations in the micrometer range. These deformations are converted into three force and torque components each via a calibration matrix.
Force/torque sensors contain a digital signal processor that continuously acquires and filters the sensor data (strain) in parallel, calculates the measurement data (forces/torques) and makes it available via the sensor's communication interface.
The measured values correspond to the forces at the sensor and usually still have to be converted into the forces and torques at the end effector or tool via a suitable transformation.
Since force/torque sensors are still relatively expensive (between €4,000 and €15,000) and very sensitive to overloads and disturbances, they - and thus force control - have been reluctantly used in industry. Indirect force measurement or estimation is one solution, allowing force control without costly and disturbance-prone force sensors.
Force estimation
A cost-saving alternative to direct force measurement is force estimation (also known as "indirect force measurement"). This makes it possible to dispense with the use of force/torque sensors. In addition to cost savings, dispensing with these sensors has other advantages: Force sensors are usually the weakest link in the mechanical chain of the machine or robot system, so dispensing with them brings greater stability and less susceptibility to mechanical faults. In addition, dispensing with force/torque sensors brings greater safety, since there is no need for sensor cables to be routed out and protected directly at the manipulator's wrist.
A common method for indirect force measurement or force estimation is the measurement of the motor currents applied for motion control. With some restrictions, these are proportional to the torque applied to the driven robot axis. Adjusted for gravitational, inertial and frictional effects, the motor currents are largely linear to the torques of the individual axes. The contact force at the end effector can be determined via the torques thus known.
Separation of dynamic and static forces
During force measurement and force estimation, filtering of the sensor signals may be necessary. Numerous side effects and secondary forces can occur which do not correspond to the measurement of the contact force. This is especially true if a larger load mass is mounted on the manipulator. This interferes with the force measurement when the manipulator moves with high accelerations.
To be able to adjust the measurement for side effects, both an accurate dynamic model of the machine and a model or estimate of the load must be available. This estimate can be determined via reference movements (free movement without object contact). After estimating the load, the measurement or estimate of the forces can be adjusted for Coriolis, centripetal and centrifugal forces, gravitational and frictional effects, and inertia. Adaptive approaches can also be used here to continuously adjust the estimate of the load.
Control concepts
Various control concepts are used for force control. Depending on the desired behavior of the system, a distinction is made between the concepts of direct force control and indirect control via specification of compliance or mechanical impedance. As a rule, force control is combined with motion control. Concepts for force control have to consider the problem of coupling between force and position: If the manipulator is in contact with the environment, a change of the position also means a change of the contact force.
Impedance control
Impedance control, or compliance control, regulates the compliance of the system, i.e., the link between force and position upon object contact. Compliance is defined in the literature as a "measure of the robot's ability to counteract contact forces." There are passive and active approaches to this. Here, the compliance of the robot system is modeled as mechanical impedance, which describes the relationship between applied force and resulting velocity. Here, the robot's machine or manipulator is considered as a mechanical resistance with positional constraints imposed by the environment. Accordingly, the causality of mechanical impedance describes that a movement of the robot results in a force. In mechanical admittance, on the other hand, a force applied to the robot results in a resulting motion.
Passive impedance control
Passive compliance control (also known as compliance control) does not require force measurement because there is no explicit force control. Instead, the manipulator and/or end effector is flexibly designed in a way that can minimize contact forces that occur during the task to be performed. Typical applications include insertion and gripping operations. The end effector is designed in such a way that it allows translational and rotational deviations orthogonal to the gripping or insertion direction, but has high stiffness in the gripping or insertion direction. The figure opposite shows a so-called Remote Center of Compliance (RCC) that makes this possible. As an alternative to an RCC, the entire machine can also be made structurally elastic.
Passive impedance control is a very good solution in terms of system dynamics, since there are no latency due to the control. However, passive compliance control is often limited by the mechanical specification of the end effector in the task and cannot be readily applied to different and changing tasks or environmental conditions.
Active impedance control
Active compliance control refers to the control of the manipulator based on a deviation of the end effector. This is particularly suitable for guiding robots by an operator, for example as part of a teach-in process.
Active compliance control is based on the idea of representing the system of machine and environment as a spring-damper-mass system. The force and the motion (position , velocity , and acceleration are directly related via the spring-damper-mass equation:
The compliance or mechanical impedance of the system is determined by the stiffness , the damping and the inertia and can be influenced by these three variables. The control is given a mechanical target impedance via these three variables, which is achieved by the machine control.
The figure shows the block diagram of a force-based impedance control. The impedance in the block diagram represents the mentioned components L, A and . A position-based impedance control can be designed analogously with internal position or motion control.
Alternatively and analogously, the compliance (admittance) can be controlled instead of the resistance. In contrast to the impedance control, the admittance appears in the control law as the reciprocal of the impedance.
Direct force control
The above concepts are so-called indirect force control, since the contact force is not explicitly specified as a command variable, but is determined indirectly via the controller parameters damping, stiffness and (virtual) mass. Direct force control is presented below.
Direct force control uses the desired force as a setpoint within a closed control loop. It is implemented as a parallel force/position control in the form of a cascade control or as a hybrid force/position control in which switching takes place between position and force control.
Parallel force/position control
One possibility for force control is parallel force/position control. The control is designed as a cascade control and has an external force control loop and an internal position control loop. As shown in the following figure, a corresponding infeed correction is calculated from the difference between the nominal and actual force. This infeed correction is offset against the position command values, whereby in the case of the fusion of and , the position command of force control ( )has a higher priority, i.e. a position error is tolerated in favor of the correct force control. The offset value is the input variable for the inner position control loop.
Analogous to an inner position control, an inner velocity control can also take place, which has a higher dynamic. In this case, the inner control loop should have a saturation in order not to generate a (theoretically) arbitrarily increasing velocity in the free movement until contact is made.
Hybrid force/position control
An improvement over the above concepts is offered by hybrid force/position control, which works with two separate control systems and can also be used with hard, inflexible contact surfaces. In hybrid force/position control, the space is divided into a constrained and an unconstrained space. The constrained space contains restrictions, for example in the form of obstacles, and does not allow free movement; the unconstrained space allows free movement. Each dimension of the space is either constrained or unconstrained.
In hybrid force control, force control is used for the restricted space, and position control is used for the unrestricted space. The figure shows such a control. The matrix Σ indicates which space directions are restricted and is a diagonal matrix consisting of zeros and ones.
Which spatial direction is restricted and which is unrestricted can, for example, be specified statically. Force and position control is then explicitly specified for each spatial direction; the matrix Σ is then static. Another possibility is to switch the matrix Σ dynamically on the basis of force measurement. In this way, it is possible to switch from position control to force control for individual spatial directions when contact or collision is established. In the case of contact tasks, all spatial directions would be motion-controlled in the case of free movement, and after contact is established, the contact direction would be switched to force control by selecting the appropriate matrix Σ.
Research
In recent years, the subject of research has increasingly been adaptive concepts, the use of fuzzy control system and machine learning, and force-based whole-body control.
Adaptive force control
The previously mentioned, non-adaptive concepts are based on an exact knowledge of the dynamic process parameters. These are usually determined and adjusted by experiments and calibration. Problems can arise due to measurement errors and variable loads. In adaptive force control, position-dependent and thus time-variable parts of the system are regarded as parameter fluctuations and are constantly adapted in the course of the control by adaptation.
Due to the changing control, no guarantee can be given for dynamic stability of the system. Adaptive control is therefore usually first used offline and the results are intensively tested in simulation before being used on the real system.
Fuzzy control and machine learning
A prerequisite for the application of classical design methods is an explicit system model. If this is difficult or impossible to represent, fuzzy controllers or machine learning can be considered. By means of fuzzy logic, knowledge acquired by humans can be converted into a control behavior in the form of fuzzy control specifications. Explicit specification of the controller parameters is thus no longer necessary.
Approaches using machine learning, moreover, no longer require humans to create the control behavior, but use machine learning as the basis for control.
Whole body control
Due to the high complexity of modern robotic systems, such as humanoid robots, a large number of actuated degrees of freedom must be controlled. In addition, such systems are increasingly used in the direct environment of humans. Accordingly, concepts from force and impedance control are specifically used in this area to increase safety, as this allows the robot to interact with the environment and humans in a compliant manner.
References
Bibliography
Robotic manipulation
Machine learning | Force control | [
"Engineering"
] | 3,986 | [
"Artificial intelligence engineering",
"Machine learning"
] |
74,611,538 | https://en.wikipedia.org/wiki/Computer%20History%20Museum%20Slovenia | The Computer History Museum Slovenia () is a museum in Slovenia dedicated to preserving the history of computing and digital heritage. Highlighting computer artifacts tied to global computer history, the museum also presents a substantial collection of items linked to early Yugoslav and Slovene computer systems.
Overview
Located in the Šiška District of Ljubljana, museum claims to host more than 6,500 collection items housed within its premises. The museum also functions as a makerspace and an event space for festivals, film shoots, coworking, conferences, public presentations and meetups. Educative workshops are organized, mostly for younger age groups, children from schools in Slovenia, Italy, and visitor groups from the region. In 'open lab' series, workshops for museum staff are open to the public, such as the one where a replica of the Apple I computer was being assembled.
The Computer History Museum is designated as a UNESCO Software Heritage Ambassador and is an active member of ICOM and the DOORS – Digital Incubator of Museums network.
History
The museum's origins are intertwined with the Cyberpipe () hackerspace, which functioned as a cultural center and hacklab. Founded by Cyberpipe hackers, the museum emerged as an integral part of the hackerspace, later becoming a separate entity. Having evolved through various incarnations since 2004, the museum initially found its home in the basement space of a student organization. At one point, the museum lost its own exhibition spaces and refocused on travelling exhibitions in other institutions. The museum gained the attention of a sponsor in 2017 who acquired a quarter of the architecturally significant brutalist building designed by Miloš Bonča. They funded its renovation, with the vision of transforming it into the future home of the museum. In 2019. the museum found its home within the former commercial pavilion building.
In 2022, the Computer History Museum hosted Jason Scott, an American archivist and technology historian affiliated with the Internet Archive and known for his documentary film BBS: The Documentary, which explores the world of Bulletin Board Systems (BBSs).
In 2023, a hands-on demonstration featuring an authentic Enigma machine took place within the premises of the museum. The event was conducted by Dr. Mark Baldwin. Attendees were given the opportunity to closely observe the artifact and to interact with it firsthand, allowing them to touch, photograph, and even play with the machine.
In 2024, the museum collaborated with Radio Študent to host a radio broadcast featuring ZX Spectrum programs. Listeners had the opportunity to record the tones from the broadcast onto cassette tapes. Upon inserting these tapes into their ZX Spectrum computers, they could load computer games. The game transmitted during this broadcast was Kontrabant 2, a Slovenian text adventure where players collect and smuggle microcomputer parts from around the world to assemble a working computer.
Exhibits
Most of the computers and devices are completely restored and functioning so visitors can try them and even use custom programs made by the museum. Early home computers and PCs are present, including TI-99/4A, TRS-80, Kaypro, Commodore 64, Amiga, ZX Spectrum, BBC Micro, Oric, Philips MSX, Sharp MZ, Atari 800, Atari ST, Apple Lisa, Apple II, Macintosh SE, Tektronix 4051, IBM PC, NeXT, Sun and SGI
workstations. In addition to personal computers, video game consoles like Vectrex, Magnavox Odyssey, Atari 2600, Intellivision and Coleco Telstar Arcade are part of the collections. DEC mainframe-like systems, terminals, and mainframe computer cabinets are on display. The domestic mainframe based on VAX is exhibited, while ADM-3A, VT52, VT100, and Minitel terminals have been connected to modern single-board computers to enable their use. Computer systems from Slovenia and former Yugoslavia are featured in the museum, including Gorenje Delta PAKA 3000, Iskra Delta Partner, Triglav, TIM-011 and Orao. Czechoslovakian analog computer MEDA 41TC is partially restored and displayed.
The museum houses an extensive collection of software, many of which are connected to Slovenia. It offers exploration into Yugoslav and Slovene MS-DOS programs and games, as well as showcases Slovenian Linux distributions and their historical significance. Additionally, there are various operating systems on display, including Windows 3.1x, Windows 95, MS-DOS, Mac OS, OS/2, and several Unix variants. Special attention is dedicated to Slovenian localized versions of operating systems.
Regarding data archiving devices and storage media, the museum claims to exhibit a diverse showcase. The IBM 129 and IBM 010 keypunch machines are on display, along with punched cards and punched tapes. Visitors can engage in classic gaming by playing games from discs, tapes, or cartridges. The collection of old telecommunication devices of various kinds is present, including early modems and acoustic couplers.
Research
The museum's team is actively delving into the history of computing in Slovenia, leading to the publication of several articles in the museum's publications. Notably, they have compiled a timeline highlighting the inaugural use of computers in Slovenia dating back to 1956. The museum's website features a dedicated section showcasing a comprehensive list of these computers. This list is categorized by year, type, location, and associated institution, complete with the necessary references for each entry.
The team has also crafted numerous articles spotlighting the pioneering domestic computer system manufacturers in Slovenia, including notable entities like Iskra Delta. This company, situated in the former Yugoslavia with a significant presence in Slovenia, was dedicated to the production of minicomputers and computer-related innovations throughout the 1970s and beyond. In these articles, the museum examines the company's production history, historical progression, anecdotes, and milestones related to Iskra Delta, providing a comprehensive view of its legacy.
See also
Iskra Delta
HomeComputerMuseum
Computer museums
History of computing
References
External links
Museums in Ljubljana
Computer museums
Šiška District
Tourist attractions in Ljubljana
Computer clubs
Hackerspaces
Cultural venues in Ljubljana
Organizations based in Slovenia
2004 establishments in Slovenia
Internet in Slovenia
Communications in Yugoslavia | Computer History Museum Slovenia | [
"Technology"
] | 1,245 | [
"Computer museums",
"History of computing"
] |
74,612,310 | https://en.wikipedia.org/wiki/1st%20Guards%20Fortified%20Region | The 1st Guards Fortified Region (, also translated as 1st Guards Fortified District) was a field fortified region of the Red Army during World War II. It was formed in early 1942 as the 76th Fortified Region and became the only fortified region to receive elite Guards status for its performance in the Rostov Offensive of 1943.
History
The 76th Fortified Region was formed at Kuznetsk in the Volga Military District between 24 April and 5 May 1942. Colonel Pyotr Sakseyev, who had previously held logistics posts, was selected to command the new unit. It included the 42nd, 45th, 46th, 47th, 48th, and 49th Separate Machine Gun Artillery Battalions. The region remained in the district until relocating to the Southeastern Front between 31 July and 12 August. It was assigned to the front's 57th Army on arrival. During the Battle of Stalingrad, the region fought in defensive battles to the south of the city. The army was shifted to the Stalingrad Front on 30 September. The region was transferred to the front's 51st Army on 6 November. It took part in the Kotelnikovo Offensive during the Soviet counteroffensive at Stalingrad. The 51st Army was shifted to the Southern Front on 1 January 1943, taking part in the Rostov Offensive in the first months of the new year. On 14 March the region was withdrawn to the front reserve. On 25 March it was assigned to the 2nd Guards Mechanized Corps of the front's 2nd Guards Army. On 13 April the region was placed under direct front control.
On 4 May 1943, the 76th was reorganized into the elite 1st Guards Fortified Region for its performance in the Rostov Offensive. On 13 May it was assigned to the front's 28th Army. On 10 July it shifted to the front's 55th Rifle Corps, and then to the 44th Army on 11 August. The region took part in the Donbass Strategic Offensive during August and September, being involved in the liberation of Taganrog and Osipenko. The region returned to the 28th Army on 10 September. Colonel Sergey Ivanovich Nikitin, relieved of command of the 4th Guards Rifle Division, became acting fortified region commander on 25 September, after Sakseyev was promoted to command the 24th Guards Rifle Division.
The fortified region took part in the Melitopol Offensive, breaking through German defenses on the Molochnaya in the region of Melitopol. When the Southern Front became the 4th Ukrainian Front, the region was placed under the control of the 28th Army's 130th Rifle Division on 20 October. It returned to army control on 26 November, and shifted to the 51st Army on 5 November. It was transferred to the 2nd Guards Army on 15 November, and subordinated to the army's 13th Guards Rifle Corps on 20 November. On 12 December the fortified region returned to 2nd Guards Army direct control.
The fortified region was transferred to the front's 28th Army on 23 February 1944, and on 28 February the army shifted to the 3rd Ukrainian Front, with which the fortified region spent the rest of the war. The fortified region took part in the Bereznegovatoye–Snigirevka offensive and then the Odessa Offensive that began in late March. During these operations, the fortified region forced a crossing of the Dniester-Southern Bug estuary and took part in the liberation of Nikolayev and Ochakov. The fortified region was transferred to the 5th Shock Army on 29 March. The fortified region received the Nikolayev honorific on 1 April 1944 for its performance in the liberation of the city of Nikolayev. On 3 April it received the Order of the Red Banner for its performance in the liberation of Ochakov. On 6 April, much of its headquarters was killed and the unit Guards Banner lost when the trawler moving them forward was blown up by a mine. 23 officers and 30 sergeants and privates were killed with only two men saved.
On 19 April it was shifted to the front's 8th Guards Army. On 29 April it was shifted to the front's 46th Army. On 20 August it was subordinated to the army's Operational Group Bakhtin for the Second Jassy–Kishinev Offensive. On 29 August it was shifted to the front's 57th Army. It was relocated between 14 and 27 September before rejoining the 57th Army, taking part in the Belgrade Offensive. On 11 October it was subordinated to the army's 64th Rifle Corps, and to its 68th Rifle Corps on 3 November. The fortified region took part in the Budapest Offensive.
On 24 December it was transferred to the front's 4th Guards Army, and on 26 December subordinated to the army's 21st Guards Rifle Corps. The fortified region was shifted to the army's 135th Rifle Corps on 6 January 1945. On 17 January, the region was at 90 percent strength in personnel with 3,122 officers and men. Early on the morning of 18 January, the positions of the fortified region were broken through by German tanks in Operation Konrad III, and its men encircled. That day the fortified region was placed under direct army control. The fortified region reported its losses in these actions as 2,232 men by the end of 22 January. Among the losses were four battalion commanders, the chiefs of its operations department and artillery, and deputy chief for political affairs. The 1st Guards Fortified Region reported the loss of 38 76 mm guns, 31 45 mm guns, seven 120 mm mortars, 33 82 mm mortars, 128 heavy machine guns, 114 light machine guns, 1,093 rifles and carbines, and 237 PPSh submachine guns, as well as all of its communications and engineer equipment. By 23 January 751 men from the unit who made it out of the encirclement concentrated at Tamási. The 1st Guards Fortified Region was transferred to the front's 7th Mechanized Corps on 29 January. The fortified region was withdrawn to the front reserve on 3 February, and on 12 February assigned to the front's 26th Army. It was transferred to the 4th Guards Army on 23 February, and on 7 March to the 35th Guards Rifle Corps of the 27th Army. It took part in the Balaton Defensive Operation.
On 28 March it was transferred to the 27th Army's 37th Rifle Corps. The fortified region was subordinated to the corps' 316th Rifle Division on 1 April and then the 35th Guards Rifle Corps' 163rd Rifle Division on 2 April. On 3 April the fortified region came under the direct control of the corps, and on 4 April it was shifted to the control of the 57th Army. Nikitin was moved up to chief of the front's Combat and Physical Training Department and replaced by 113th Rifle Division commander Colonel Stepan Kiryan on 17 April. On 21 April it was shifted to the 4th Guards Army, and on 26 April subordinated to the army's 31st Guards Rifle Corps.
Postwar
After the end of the war, the fortified region was transferred to the direct control of the 3rd Ukrainian Front on 3 June, and transferred to the Southern Group of Forces on 15 June. The 1st Guards Fortified Region was withdrawn to the Odessa Military District on 16 August. The fortified region was disbanded in the Odessa Military District between 17 May and 4 July 1946.
Commanders
The following officers, holding the title of commandant, commanded the fortified region:
Colonel Pyotr Ivanovich Sakseyev (24 April 1942 – 24 September 1943)
Colonel Sergey Ivanovich Nikitin (25 September 1943–c. 15 April 1945)
Colonel Stepan Vasilyevich Kiryan (17 April–5 November 1945)
General-mayor Yeremey Zakharovich Karamanov (5 November 1945 – 30 June 1946)
The following officers served as chiefs of staff of the fortified region:
Major Nikolay Fyodorovich Likholetov (24 April–20 November 1942)
Colonel Vasily Ivanovich Argunov (20 November 1942 – 6 June 1946)
Order of battle
The following machine gun artillery battalions were assigned to the fortified region during its existence:
42nd Separate Machine Gun Artillery Battalion (5 May–5 November 1942)
45th Separate Machine Gun Artillery Battalion (5 May–20 November 1942)
46th Separate Machine Gun Artillery Battalion (5 May–30 July 1943)
47th Separate Machine Gun Artillery Battalion (5 May–5 November 1942)
48th Separate Machine Gun Artillery Battalion (5 May–5 November 1942)
49th Separate Machine Gun Artillery Battalion (5 May–5 November 1942)
51st Separate Machine Gun Artillery Battalion (5 November 1942 – 30 July 1943)
36th Separate Machine Gun Artillery Battalion (9 May–30 July 1943)
168th Separate Machine Gun Artillery Battalion (9 May–30 July 1943)
170th Separate Machine Gun Artillery Battalion (9 May–30 July 1943)
148th Separate Machine Gun Artillery Battalion (10 August–1 September 1943)
2nd Guards Separate Machine Gun Artillery Battalion (10 August 1943 – 20 June 1946), converted from the 46th Separate Machine Gun Artillery Battalion 1 July 1943
8th Guards Separate Machine Gun Artillery Battalion (10 August 1943 – 20 June 1946), converted from 51st Separate Machine Gun Artillery Battalion 4 May 1943
9th Guards Separate Machine Gun Artillery Battalion (10 August 1943 – 20 June 1946), converted from 36th Separate Machine Gun Artillery Battalion 4 May 1943
10th Guards Separate Machine Gun Artillery Battalion (10 August 1943 – 20 June 1946), converted from 170th Separate Machine Gun Artillery Battalion 23 May 1943
11th Guards Separate Machine Gun Artillery Battalion (10 August 1943 – 20 June 1946), converted from 168th Separate Machine Gun Artillery Battalion 4 May 1943
Support units included:
161st Separate Trench Flamethrower Company (25 April 1942 – 30 July 1943)
376th Separate Signals Company (25 April 1942 – 30 July 1943)
33rd Guards Separate Signals Company (30 July 1943 – 20 June 1946)
2356th Field Postal Station (20 December 1942 – 20 February 1943)
40202nd Field Postal Station (20 April 1943–Unknown)
156th Separate Motor Rifle Battalion (1 August 1942 – 20 February 1943)
Separate Training Machine Gun Artillery Battalion (1 January–20 June 1946)
41st Separate Engineer Company (1 January–20 June 1946)
867th Auto-Transport Company (1 January–20 June 1946)
670th Medical-Sanitary Company (1 January–20 June 1946)
835th Field Bakery (1 January–20 June 1946)
References
Citations
Bibliography
Fortified regions of the Soviet Union
Red Army units and formations of World War II
Military units and formations disestablished in 1946
Military units and formations awarded the Order of the Red Banner | 1st Guards Fortified Region | [
"Engineering"
] | 2,140 | [
"Fortification lines",
"Fortified regions of the Soviet Union"
] |
74,612,603 | https://en.wikipedia.org/wiki/Kenneth%20John%20Packer | Kenneth John Packer FRS (18 May 1938 – 18 September 2021) was a British nuclear magnetic resonance (NMR) scientist who was amongst the pioneers of NMR application in the second half of the 20th century.
Born in Kettering, Packer studied chemistry at Imperial College London, before embarking on a PhD at the University of Cambridge, where his career in the field of NMR and its applications would begin. His NMR research was established at the School of Chemistry at the University of East Anglia (UEA), where he remained for twenty years from 1964 to 1984. He then left academia for almost a decade, working for BP Research, before returning as research chair in the chemistry department of the University of Nottingham, where he remained until retirement in 2001.
He received the Royal Society of Chemistry's Medal for Analytical Spectroscopy in 1986. He was elected Fellow of the Royal Society in 1991.
References
1938 births
2021 deaths
Fellows of the Royal Society
Nuclear magnetic resonance
People from Kettering
20th-century British scientists
21st-century English scientists
Alumni of Imperial College London
Alumni of the University of Cambridge
Academics of the University of East Anglia
BP people
Academics of the University of Nottingham | Kenneth John Packer | [
"Physics",
"Chemistry"
] | 236 | [
"Nuclear magnetic resonance",
"Nuclear physics"
] |
74,614,082 | https://en.wikipedia.org/wiki/Riggs%20Award%20for%20Lifetime%20Achievement%20in%20International%20and%20Comparative%20Public%20Administration | The Riggs Award for Lifetime Achievement in International and Comparative Administration is an academic award given annually by the Section on International and Comparative Administration of the American Society for Public Administration.
The Award is named in honor of Fred W. Riggs, a political scientist and pioneer in the field of comparative administration in the United States. Riggs was the founder and first chairperson of the Comparative Administration Group, which was later reorganized as the Section on International and Comparative Administration of the American Society for Public Administration. Riggs argued that “the new paradigm for public administration must be comparative, since the solution of the problem to which it addresses itself will require increasing communication between scholars and practitioners in all countries." Since 1986, the Award has been given annually to an individual "in recognition of lifetime scholarly achievement in the field of comparative and public administration."
Recipients
References
Academic awards
Research awards
Public administration
Public policy
Subfields of political science
International development | Riggs Award for Lifetime Achievement in International and Comparative Public Administration | [
"Technology"
] | 184 | [
"Science and technology awards",
"Research awards"
] |
74,617,116 | https://en.wikipedia.org/wiki/HD%20180134 | HD 180134 (HR 7297; 52 G. Telescopii) is a solitary star located in the southern constellation Telescopium. It has an apparent magnitude of 6.36, placing it near the limit for naked eye visibility, even under ideal conditions. The object is located relatively close at a distance of 148.4 light-years based on Gaia DR3 parallax measurements, and it is drifting closer with a heliocentric radial velocity of . At its current distance, HD 180134's brightness is diminished by two-tenths of a magnitude due to interstellar extinction and it has an absolute magnitude of +3.09.
HD 180134 has a stellar classification of F7 V, indicating that it is an ordinary F-type main-sequence star that is currently generating energy via hydrogen fusion at its core. It has 1.32 times the mass of the Sun and 1.9 times the radius of the Sun. It radiates 4.93 times the luminosity of the Sun from its photosphere at an effective temperature of , giving a whitish-yellow hue when viewed in the night sky. HD 180134 is slightly metal deficient with an iron abundance 93% that of the Sun or [Fe/H] = −0.03, and it spins modestly with a projected rotational velocity of approximately . At the age of 3.28 billion years, it is 1.49 magnitudes above the zero age main sequence, meaning that it is evolved.
In 2006, an infrared excess was detected around the star, which could indicate the presence of a circumstellar disk. The disk has a temperature less than 145 K, making it a cool disk; it has an angular separation greater than 0.19 arcseconds or a physical separation greater than 8.6 astronomical units.
References
F-type main-sequence stars
Circumstellar disks
Telescopium
Telescopii, 52
CD-53 08089
180134
094858
7297 | HD 180134 | [
"Astronomy"
] | 419 | [
"Telescopium",
"Constellations"
] |
74,619,486 | https://en.wikipedia.org/wiki/Pet%20humanization | Pet humanization is the practice in pet culture of treating companion animals with a level of care, attention, and luxury relatively higher than for the average domesticated animal. This trend involves the owners being at odds with the pet's status as property in wider society and can range from relying on them for emotional support to treating them like human family members.
To the extent that the treatment involves providing for the pet beyond their means of appreciation, it is considered to be a form of anthropomorphism though the limits of this remain an open topic.
History
In many ancient civilizations, people formed close bonds with animals, often using them for various purposes like hunting, protection, companionship, and animal worship. For example, some cats in ancient Egypt were considered sacred animals and were personified with the deity Bastet, and provided with elaborate burials. Dogs in religion hold various symbolic and cultural meanings across different religions and belief systems.
The modern concept of pet humanization began to gain significant momentum in Western culture and societies during the 19th century and continued to grow throughout the 20th century, along with the present day.
In the mid-20th century, the pet industry started to expand, offering a wide range of products and services which cater to pet owners' desires to provide the best possible care for their animals. This included the development of specialized pet foods, veterinary medicine, grooming services, and even luxury items.
In the modern era, this trend reflects changing societal attitudes towards pets, where they are seen less as a property and more as valued members of the family.
Key aspects
Key aspects of pet humanization include owners that may prioritize premium or organic pet food, special diets, and even preparing homemade meals for their pets. Pets receive regular check-ups, vaccinations and even medical treatments that were once uncommon. Pets may have a wide array of accessories such as clothing, collars, leashes, and even designer items. Luxurious pet accommodations, such as elaborate pet beds or specialized animal furniture, may be used. Pets are provided with toys, entertainment and enrichment activities to keep them mentally stimulated. Pets might have birthdays celebrated with parties, special treats, and social gatherings. Pet-friendly accommodations and travel arrangements are made for vacations or trips. There are times when pets have their own social media profiles with followers and interactions. Owners often form deep emotional bonds with their pets, considering them as family members and seeking companionship and emotional support from them.
Human psychology
The psychology behind pet humanization involves understanding the motivations, emotions and behaviours that drive individuals to treat their pets as more than just animals and instead as valued members of the family or even as surrogate companions.
Humans have a natural inclination to form emotional bonds with other living beings, and pets often provide unconditional love, companionship, and a sense of belonging. This emotional connection can lead to the desire to provide the best possible care and attention to pets.
Anthrozoology
Anthrozoology is the interdisciplinary study of the interactions and relationships between humans and animals. It encompasses a wide range of topics related to human-animal interactions, including the emotional, psychological, social, and biological aspects of these relationships.
Pet humanization is a concept within the field of anthrozoology that focuses on the tendency of humans to attribute human-like qualities and behaviours to their pets.
Pet food industry
Pet humanization has a significant impact on the pet food industry, leading to changes in consumer preferences, product offerings, and marketing strategies. As pet owners increasingly view their pets as integral members of their families, they seek out higher quality and more specialized food options for their pet companions. Pet owners who humanize their pets often seek pet foods made with high-quality, natural, and wholesome ingredients. This has led to a rise in demand for premium pet foods that are free from artificial additives, preservatives and fillers.
Pet healthcare
Pet healthcare and pet humanization has had a notable impact on the health care of pets, leading to changes in how pet owners approach veterinary care, preventive measures, medical treatments, and overall wellness for their animal companions.
Pet insurance is considered a component of pet humanization because it reflects the growing trend of treating pets as members of the family and providing them with similar care and services that humans receive.
Pet bereavement
Pet bereavement and pet humanization are two concepts that are closely related and often intersect in the realm of human-pet relationships.
Pet bereavement is the emotional response that pet owners experience when their pets pass away. It involves a range of emotions similar to the mourning process for a human loved one.
See also
Further reading
Bartz, J. A., Tchalova, K., & Fenerci, C. (2016). Reminders of social connection can attenuate anthropomorphism: A replication and extension of Epley, Akalis, Waytz, and Cacioppo (2008). Psychological Science, 27(12), 1644–1650.
Borgi, M., & Cirulli, F. (2016). Pet face: Mechanisms underlying human-animal relationships. Frontiers in Psychology, 7, 298.
Epley, N., Waytz, A., & Cacioppo, J. T. (2007). On seeing human: A three-factor theory of anthropomorphism. Psychological Review, 114(4), 864–886. doi:10.1037/0033-295X.114.4.864
Epley, N., Waytz, A., Akalis, S., & Cacioppo, J. T. (2008). When we need a human: Motivational determinants of anthropomorphism. Social Cognition, 26(2), 143–155.
Heider, F., & Simmel, M. (1944). An experimental study of apparent behavior. The American Journal of Psychology, 57(2), 243–259.
Mourey, J. A., Olson, J. G., & Yoon, C. (2017). Products as pals: Engaging with anthropomorphic products mitigates the effects of social exclusion. Journal of Consumer Research, 44(2), 414–431.
Paul, E. S., Moore, A., McAinsh, P., Symonds, E., McCune, S., & Bradshaw, J. W. (2014). Sociality motivation and anthropomorphic thinking about pets. Anthrozoös, 27(4), 499–512.
Tam, K.-P., Lee, S.-L., & Chao, M. M. (2013). Saving Mr. Nature: Anthropomorphism enhances connectedness to and protectiveness toward nature. Journal of Experimental Social Psychology, 49(3), 514–521.
References
External links
Animal cognition
Human–animal interaction
Animal rights
Anthropomorphism
Cats as pets
Dogs as pets
Human behavior
Popular psychology
Psychological concepts | Pet humanization | [
"Biology"
] | 1,464 | [
"Behavior",
"Animals",
"Human behavior",
"Animal cognition"
] |
57,886,751 | https://en.wikipedia.org/wiki/NGC%203840 | NGC 3840 is a spiral galaxy located about 320 million light-years away in the constellation Leo. The galaxy was discovered by astronomer Heinrich d'Arrest on May 8, 1864. NGC 3840 is a member of the Leo Cluster. The galaxy is rich in neutral atomic hydrogen (H I) and is not interacting with its environment.
NGC 3840 is likely to be a low-luminosity AGN (LLAGN).
See also
List of NGC objects (3001–4000)
References
External links
3840
36477
6702
Leo (constellation)
Leo Cluster
Spiral galaxies
Astronomical objects discovered in 1864
Active galaxies | NGC 3840 | [
"Astronomy"
] | 127 | [
"Leo (constellation)",
"Constellations"
] |
57,886,801 | https://en.wikipedia.org/wiki/Dictyota | Dictyota is a genus of brown seaweed in the family Dictyotaceae. Species are predominantly found in tropical and subtropical seas, and are known to contain numerous chemicals (diterpenes) which have potential medicinal value. As at the end of 2017, some 237 different diterpenes had been identified from across the genus.
Taxonomy and Nomenclature
The genus Dictyota was first described by Jean Vincent Lamouroux in 1809. The name Dictyota is derived from the Greek word “Διχτυον” meaning “net” or “network”, referring to the inner cellular structure of specimens when viewed under a microscope, which features netted cortical and medullary cells.
Dictyota belongs to the order Dictyotales and the SSDO-clade, which also includes the orders Sphacelariales, Syringodermatales, and Onslowiales. The family Dictyotaceae is divided into two tribes: Dictyoteae and Zonarieae. The former have a single lens-shaped apical cell from which the thallus grows, while the latter are characterized by a row or cluster of apical cells. The genera Glossophora, Glossophorella, and Pachdictyon are synonyms of Dictyota as DNA sequencing revealed that they were closely related.
Morphology
External characteristics
Dictyota has "flat, ribbon-like axes" which exhibit dichotomous branching that may be either isotomous (equal or symmetrical) or anisotomous (unequal). Isotomous branches may be recurved, while anisotomous branches may become falcate (hooked), or cervicorn, if combined with twisting axes. Apical meristems of Dictyota species have been reported to be either truncate, rounded, or acute. A considerable degree of morphological plasticity has been observed from branching patterns, thus making molecular analyses indispensable when identifying species.
Colors of living thalli range from dark brown to green (as in D. friabilis) or blue (as in D. cyanoloma). The thalli grow from apical cells which differentiate into an outer cortical and an inner medullary cell layer. Cortical cells on the margins of the thalli may grow into leaf-like projections or teeth (as in D. ciliolata and D. cyanoloma) while adventitious branches may grow from the central cortical cells. Thalli may also grow hair (20-50 um in diameter). Thalli attach to the substrate via rhizoids which are multicellular, uniseriate, branching, and hyaline (glassy or transparent). Different species may have one or several attachment points which can lead to a wide range of growth forms (i.e. creeping thalli or fully erect).
Internal anatomy
The thalli are parenchymatous and are characterized by one or more apical cells that divide into an outer cortical and an inner medullary cell layer which can have several different configurations (e.g. uni-layered cortex with unilayered medulla, uni-layered cortex with multi-layered medulla, etc.).
Distribution
Dictyota is distributed along tropical to temperate waters with species having generally restricted geographic ranges. It is the most abundant genus of brown algae in the Mediterranean Sea as well as the Atlantic coasts of Europe.
Ecology
Species of the genus are commonly found in subtidal to intertidal rocky pools. Seasonality in species' abundances as well as fertility are driven mainly by temperature, photoperiod, and solar radiation. For instance, populations of D. dichotoma in the southern hemisphere are highly abundant for a majority of the year but are largely absent in the warmer months, which is when its northern counterparts are most abundant and fertile.
Life History
Dictyota exhibits an isomorphic life cycle wherein the alternating gametophyte and sporophyte phases appear morphologically similar. This alternation co-occurs with a change in ploidy. The gametophytes produce gametes which undergo fertilization to produce the diploid sporophyte, which then produces sporangia which will release 4 haploid spores through meiosis. Half of the haploid spores will develop into the female gametophytes while the other half will develop into male gametophytes, starting the process over again.
Dictyota is dioecious and reproduces both sexually and asexually. Release of gametes follows a diurnal and lunar periodicity. Gametes are often released 20–30 minutes after first light, with peaks occurring once or twice a month depending on the species. Asexual reproduction may occur via adventitious branching following the loss of the apical meristem.
Chemical Composition
Dictyota is known to have high levels of fatty acids and lipids which makes the genus ideal for use as feedstock. The pigments found in Dictyota are Chlorophyll a, c, fucoxanthin and violaxanthin which are present in a ratio of 13:3:10:1. This ratio may be altered by depth.
Exploitation/Utilization and Management
The genus is not currently cultivated nor harvested on an industrial scale. It is mainly exploited for its secondary metabolites which are known to have anticoagulant, antibacterial, anti-inflammatory properties, among others, making them useful for a wide range of pharmaceutical applications. For instance, there is evidence that methanolic extracts of Dictyota inhibits the butyrylcholinesterase (BuChE) enzyme in humans, which could potentially treat Alzheimer's disease.
Other applications include its use as biofuel - due to the high lipid content of some species - and as supplemental feeds for poultry, cattle, and fish. A study in 2014 found that feeds with D. bartayresiana supplements could potentially reduce in vitro methane production of ruminants by 92.2%, which may have implications for reducing emissions from the agricultural sector.
Species
The genus Dictyota contains the following species:
Dictyota acutiloba J.Agardh, 1848
Dictyota adhaerens Noda, 1965
Dictyota adnata Zanardini, 1878
Dictyota adnata f. nana Post
Dictyota aegerrima (Allender & Kraft) De Clerck, 2006
Dictyota alternifida J.Agardh, 1894
Dictyota anastomosans Steen et al.
Dictyota apiculata var. Agardh Weber-van Bosse
Dictyota asiatica I.K.Hwang
Dictyota attenuata P.Crouan & H.Crouan, 1842
Dictyota bartayresiana J.V.Lamouroux, 1809
Dictyota bartayresiana var. divaricata Kützing
Dictyota bifurca J.Agardh, 1894
Dictyota binghamiae J.Agardh, 1894
Dictyota canaliculata O.De Clerck & E.Coppejans, 1997
Dictyota canariensis (Grunow) Tronholm, 2013
Dictyota caribaea Hörnig & Schnetter, 1992
Dictyota cervicornis f. pseudodichotoma Taylor
Dictyota cervicornis f. spiralis Taylor<ref name="AB"
Dictyota ceylanica var. anastomosans Yamada
Dictyota chalchicueyecanensis Lozano-Orozco & Sentíes
Dictyota ciliata var. humilis Grunow
Dictyota ciliolata Sonder ex Kützing, 1859
Dictyota concrescens W.R.Taylor, 1945
Dictyota coriacea (Holmes) I.K.Wang, H.-S.Kim & W.J.Lee, 2004
Dictyota crenulata J.Agardh, 1847
Dictyota cribrosa Setchell & N.L.Gardner, 1930
Dictyota crinita (J.Agardh) Hörnig, Schnetter & Prud'Homme van Reine, 1992
Dictyota crux
Dictyota crux f. parva A.Bachmann
Dictyota cuneata Dickie, 1874
Dictyota cyanoloma Tronholm, De Clerck, A.Gómez-Garreta & Rull Lluch, 2010
Dictyota cymatophila Tronholm, M.Sanson & Afonso-Carrillo, 2010
Dictyota decumbens (R.W.Ricker) Hörnig, Schnetter & Prud'homme van Reine, 1992
Dictyota detergenda Kraft, 2009
Dictyota dhofarensis (Nizamuddin & A.C.Campbell) De Clerck, 2006
Dictyota dichotoma (Hudson) J.V.Lamouroux, 1809
Dictyota dichotoma Suhr, 1839
Dictyota dichotoma f. angustior Schiffner
Dictyota dichotoma var. fimbriata Piccone & Grunow
Dictyota dichotoma var. genuina Grunow
Dictyota dichotoma var. guinea Grunow
Dictyota dichotoma var. inequalis S.F.Gray
Dictyota dichotoma var. intricata (C.Agardh) Greville
Dictyota dichotoma var. patens
Dictyota dichotoma f. proliferans Ercegovic
Dictyota diemensis Sonder ex Kützing, 1859
Dictyota dilatata Yamada, 1925
Dictyota divaricata P.L.Crouan & H.M.Crouan, 1865
Dictyota dolabellana De Paula, Yoneshigue-Valentin & Teixeira, 2008
Dictyota dumosa Børgesen, 1935
Dictyota fasciculata Sperk, 1869
Dictyota fascida J.Agardh, 1898
Dictyota fasciola var. abyssinica J.Agardh
Dictyota fasciola (Roth) J.V.Lamouroux, 1809
Dictyota fasciola var. divergens f. major Schiffner
Dictyota fasciola var. divergens f. minor Schiffner
Dictyota fasciola var. elongata De Notaris
Dictyota fasciola f. major Schiffner
Dictyota fasciola f. minor Schiffner
Dictyota fasciola var. repens (J.Agardh) Ardissone
Dictyota fastigiata Sonder, 1845
Dictyota fenestrata J.Agardh, 1894
Dictyota flabellata (F.S.Collins) Setchell & N.L.Gardner, 1924
Dictyota flabellulata Foster & Schiel
Dictyota flagellifera Kraft, 2009
Dictyota foliosa J.Agardh, 1892
Dictyota friabilis Setchell, 1926
Dictyota furcellata (C.Agardh) Greville, 1830
Dictyota galapagensis (Farlow) De Clerck, 2006
Dictyota grossedentata De Clerck & Coppejans, 1999
Dictyota guajirae Hörnig, Schnetter & J.M.Over, 1992
Dictyota guineënsis (Kützing) P.L.Crouan & H.M.Crouan, 1878
Dictyota gunniana (J.Agardh) I.Hörnig, R.Schnetter & Prud'homme van Reine, 1992
Dictyota hamifera Setchell, 1926
Dictyota harveyana
Dictyota hauckiana Nizamuddin, 1975
Dictyota humifusa Hörnig, Schnetter & Coppejans, 1992
Dictyota implexa (Desfontaines) J.V.Lamouroux, 1809
Dictyota indica Anand, 1965
Dictyota inscripta J.Agardh, 1893
Dictyota intermedia Zanardini, 1874
Dictyota jamaicensis W.R.Taylor, 1960
Dictyota kunthii (C.Agardh) Greville, 1830
Dictyota laciniata J.V.Lamouroux, 1809
Dictyota lata J.V.Lamouroux, 1809
Dictyota linearis var. campsosticha Montagne
Dictyota linearis f. intricata Kützing
Dictyota linearis var. major P.Crouan & H.Crouan
Dictyota linearis var. minor Sonder
Dictyota littoralis P.Anand, 1965
Dictyota liturata J.Agardh, 1848
Dictyota major W.R.Taylor, 1945
Dictyota masonii Setchell & N.L.Gardner, 1930
Dictyota mayae Lozano-Orozco & Sentíes
Dictyota mediterranea (Schiffner) G.Furnari, 1997
Dictyota menstrualis (Hoyt) Schnetter, Hörnig & Weber-Peukert, 1987
Dictyota mertensii (C.Martius) Kützing, 1859
Dictyota moniliformis (J.Agardh) Hörnig, Schnetter & Prud'homme van Reine, 1992
Dictyota multifida (J.E.Smith) Bory, 1838
Dictyota naevosa (Suhr) Montagne, 1840
Dictyota nigrescens Zanardini, 1878
Dictyota nigricans J.Agardh, 1882
Dictyota ocellata J.Agardh, 1894
Dictyota pachyderma Luan Rixiao & Ding Lanping
Dictyota paniculata J.Agardh, 1841
Dictyota papenfussii Lindauer, 1949
Dictyota pavonia var. maxima J.V.Lamouroux
Dictyota pedrochei Lozano-Orozco & Sentíes
Dictyota pellucida J.Agardh, 1892
Dictyota penicellata J.V.Lamouroux
Dictyota phlyctaenodes Montagne, 1852
Dictyota pinnata (E.Y.Dawson) I.Hörnig, R.Schnetter & Prud'homme van Reine, 1993
Dictyota pinnatifida Kützing, 1859
Dictyota pinnatifida var. rigida Grunow
Dictyota plantaginea J.V.Lamouroux ex Frauenfeld, 1855
Dictyota plectens (Allender & Kraft) Kraft, 2009
Dictyota pleiacantha Tronholm, 2013
Dictyota polyclada Sonder ex Kützing
Dictyota pontica Sperk, 1869
Dictyota pulchella Hörnig & Schnetter, 1988>
Dictyota rhizodes (Turner) J.V.Lamouroux
Dictyota rigida De Clerck & Coppejans, 1999
Dictyota robusta J.Agardh, 1894
Dictyota rotunda C.Agardh, 1820
Dictyota sandvicensis Sonder, 1859
Dictyota serrulata J.V.Lamouroux, 1809
Dictyota spathulata Yamada, 1928
Dictyota spinulosa J.D.Hooker & Arnott, 1838
Dictyota spiralis Montagne, 1846
Dictyota stolonifera E.Y.Dawson, 1962
Dictyota suhrii (Kützing) I.Hörnig, R.Schnetter & W.F.Prud'homme van Reine, 1992
Dictyota vieillardii Kützing, 1863
Dictyota vieillardii var. filiformis Kützing
Dictyota virellus Noda, 1971
Dictyota vittata Kraft, 2009
Dictyota vivesii M.A.Howe, 1911
References
Dictyotaceae
Brown algae genera
Seaweeds | Dictyota | [
"Biology"
] | 3,584 | [
"Seaweeds",
"Algae"
] |
57,887,390 | https://en.wikipedia.org/wiki/Aurora%20Pulsed%20Radiation%20Simulator | The Aurora Pulsed Radiation Simulator (also known as the Aurora flash x-ray simulator) was a 14-terawatt flash gamma-ray simulator, designed to simulate the effects of a nuclear weapon's bremsstrahlung, or gamma radiation, pulses on military electronic systems. It was built in 1971 by the U.S. Defense Atomic Support Agency (DASA), which eventually became the Defense Threat Reduction Agency, and the U.S. Department of Energy (DOE).
The Aurora Simulator was more than long and weighed 1,450 tons; it was the first gamma radiation simulator of its size in the world at the time. It was also one of only four large machines in the United States built specifically to test complete nuclear weapons packages, with the other three being the Hermes I to III simulators at Sandia Base, New Mexico. Situated at the Harry Diamond Laboratories (which later became a part of the Army Research Laboratory) in Adelphi, Maryland, it was used to test complete weapons electronics packages from the warheads of intercontinental ballistic missiles (ICBMs) to satellites. After more than 20 years of use during the Cold War, the Aurora Simulator was officially decommissioned and disassembled in 1996.
In 1986, the Aurora facility set the world record for the largest amount of high-power microwave power generated from a virtual cathode oscillator. As a result, HDL was recognized by the American Defense Preparedness Association (ADPA) in 1987.
History
Following the use of the atomic bomb in World War II and subsequent development, it became clear that much of the damage they produce comes from powerful, short (sub-microsecond) pulses of various kinds of radiation. Exactly how this works depends, among other particulars, on where the bomb explodes: if it's inside some material, underground and even in air, a primary effect is a shock wave from the expanding bomb material (which, itself, remains more or less in place). However, x-rays with energies between about 1 and 10 MeV, which are least absorbed by materials, can radiate far outside the immediate region of the explosion even as they are gradually absorbed by the material they pass through. In air, they go just about 1000 times farther than they would in water. Since all the x-rays go at the light speed, their pulse shape reflects the explosion itself: much shorter than a microsecond. Sub-MeV radiation from a nuclear explosion may be more important in (empty) space. Given this realization, during the 1960s the U.S. military began to investigate whether military systems could be tested for their response to nuclear-weapon generated pulsed x-rays with flash x-ray machines. At the time these were fairly small, primarily used to take x-rays of fast-moving events such as explosives and bullets.
After the Soviet Union demonstrated the use of the world's first anti-ballistic missiles (ABM) in 1964, in response DASA launched a series of projects that aimed to hasten the advancement of nuclear effects laboratories in the United States. The U.S. military was concerned that the introduction and subsequent nuclear explosion of Soviet AMBs into the airspace would result in radiation that could interfere with the electronics systems of inbound U.S. ICBMs. In order to thoroughly harden U.S. missiles, in 1969 DASA initiated the construction of the Aurora Simulator as a gamma radiation test facility that could produce full-threat level pulses of 1 to 10 MeV photons ("gamma" radiation refers to x-rays (or photons) emitted by nuclei and typically more energetic than 1 MeV).
When selecting the site for the Aurora facility, DASA wanted the gamma radiation simulator to be situated at an existing military laboratory. After much deliberation between the Air Force Weapons Laboratory (AFWL) in New Mexico and the Army and Navy laboratories in the Washington, D.C. area, DASA chose the latter and granted the Harry Diamond Laboratory (HDL) the responsibility of operating the facility. In order to house the Aurora Simulator, HDL moved from its downtown Washington, D.C. site to an area of land in White Oak, Maryland, which would eventually become the ARL Adelphi site.
The cooperation between DASA and HDL on the Aurora project led to many HDL researchers becoming involved in the simulator's development, including assistant to DASA Deputy Director for Science and Technology Peter Haas and former participant in the Manhattan Project Paul Caldwell, who later was placed in charge of the Aurora Simulator. In turn, Caldwell hired physicist Alexander Stewart from Ion Physics (IP) and HDL's Robert Lamb and Dennis Whittaker, the four of whom (including Caldwell) made up the bulk of the research and development team for the Aurora project. The construction of the Aurora Simulator was completed in January 1971, costing about $16 million, and the first test was conducted on the Spartan ABM flight control set in April 1972. Throughout its entire run at HDL, which ended in 1995, the Aurora Simulator conducted 287 numbered tests, resulting in more than 9,100 test shots.
Operation
The Aurora Pulsed Radiation Simulator consisted of four 14 MV Marx generators, each of which contained four parallel 1.25 MJ units connected together to drive four parallel oil-dielectric Blumlein pulse-forming lines (PFLs). Each PFL was coupled with an E-beam diode.
The Aurora Simulator produced four short pulses of high energy bremsstrahlung radiation that overlapped to deliver a single 120 ns wide pulse of 20 to 50 krads (Si) into a 1m cube. It could also deliver 25 krads (Si) throughout a 1m diameter and 1m long cylindrical volume or 50 krads (Si) throughout a 25 cm sphere. What made the Aurora Simulator unique was its ability to provide such a high dose uniformly throughout the nominally cubic-meter volume, which sometimes needed dose measurements at up to 200 locations within a single electronics system. However, in order to obtain the desired radiation levels, all four 230-kA bremsstrahlung pulses had to overlay within 10 ns. This synchronization was made possible by the symmetrization of the four Blumleins that was achieved only just before the facility was closed. During active testing, the Aurora Simulator could do as many as 13 test shots in a single day. In comparison, nuclear weapons testing at the Nevada Test Site was limited to one test shot per three months.
There were two main limitations to the operation of the Aurora Simulator. Early on, the long discharge time of the Blumeins sometimes allowed unintended arcs through the oil to shorten or even prevent the bremsstrahlung pulses. In the early 1990s this problem was solved by improvements in triggering the Blumlein's V/N oil switch. Second, the 40-Ohm impedance of the Blumleins made it inefficient to drive low impedance loads.
References
Nuclear research institutes
Military research of the United States
Military technology
Pulsed power
Electronics manufacturing
Radiation effects | Aurora Pulsed Radiation Simulator | [
"Physics",
"Materials_science",
"Engineering"
] | 1,461 | [
"Nuclear research institutes",
"Physical phenomena",
"Electronics manufacturing",
"Nuclear organizations",
"Physical quantities",
"Materials science",
"Power (physics)",
"Electronic engineering",
"Radiation",
"Condensed matter physics",
"Radiation effects",
"Pulsed power"
] |
57,893,298 | https://en.wikipedia.org/wiki/Remote%20Activation%20Munition%20System | The Remote Activation Munition System (RAMS) is a radio frequency controlled system that is used to remotely detonate demolition charges. It can also be used to remotely operate electronic equipment such as beacons, laser markers, and radios.
RAMS was developed by a team of researchers led by James Chopak at the Army Research Laboratory from 1996 to 2000. The system consists of a transmitter and two different types of receivers, one to initiate blasting caps and one to initiate C4 directly.
RAMS was designed to serve as a more portable and convenient alternative to conventional remote activation systems like the model XM-122, which was considered too big, heavy, and fragile for efficient use. In addition, the XM-122 was limited in its range (about 1 km) and relied on very large high capacity batteries.
In contrast, the RAMS weighed only a couple pounds and its microprocessor-based transmitter was powered by at most seven standard 9-volt batteries. The device was capable of reaching a range up to 2 kilometers, and the combination of the crystal filter in the receivers and the FM detector circuit made it possible to maintain high signal sensitivity at a low power consumption rate.
In addition, the RAMS was operational in harsh environments with temperatures as low as and as high as . It was also capable of functioning when submerged in saltwater, up to depths of . However, testing performed by the Army Research Laboratory have found that due to the low power levels of the RAMS receiver’s electrical signals output, the system has demonstrated a noticeable level of unreliability in performance past a certain distance.
More modern versions of the RAMS can weigh as little as and can reach a range of more than 5 kilometers, allowing operators to stand farther away from the blast at a safer distance.
References
Radio waves
Military technology
Explosives engineering | Remote Activation Munition System | [
"Technology",
"Engineering"
] | 366 | [
"Information and communications technology",
"Explosives engineering",
"Telecommunications engineering",
"Radio technology"
] |
57,893,503 | https://en.wikipedia.org/wiki/Magneto%20Inductive%20Remote%20Activation%20Munition%20System | The Magneto Inductive Remote Activation Munition System (MI-RAMS) is a variant of the Remote Munition System (RAMS) that uses electromagnetic induction to control electronic equipment, including demolition charges, munitions, and active barriers. The handheld MI-RAMS receiver consists of a box-shaped device with a fixed bulkhead-style receptacle connector on the top with a non-leaking metal shell threaded in the rear section of the connector and sealed with an O-ring.
With the use of quasi-static AC magnetic fields, MI-RAMS is capable of sending signals through ice, rock, soil, water, and concrete. As a result, MI-RAMS is often used to remotely control ordnance items and communication systems in areas in which radio frequency devices under-perform or fail. These areas include caves, bunkers, tunnels, dense jungle, ice fields, urban structures, and up to 66 feet underwater. The wireless channel created by MI-RAMS does not produce any far field (RF) emissions, which decreases likelihood of detection outside of the operating area. The MI-RAMS transmitters and receivers have also been designed to work with existing communication technology, allowing other types of handsets to link to the system and communicate with each other as long as one MI-RAMS unit is present.
MI-RAMS was designed and modified by researchers at the Army Research Laboratory for U.S. Army Combat Engineer Forces and Army and Navy Special Operations Forces (SEALs) to aid in establishing terrain dominance.
References
Military technology
Radio waves
Explosives engineering | Magneto Inductive Remote Activation Munition System | [
"Technology",
"Engineering"
] | 311 | [
"Information and communications technology",
"Explosives engineering",
"Telecommunications engineering",
"Radio technology"
] |
57,893,657 | https://en.wikipedia.org/wiki/Third%20Arm%20Weapon%20Interface%20System | The Third Arm Weapon Interface System (TAWIS), or Third Arm, is a passive, stabilizing device developed by the US Army Research Laboratory (ARL) in 2016 to redistributes the weight of heavy firearms to make them easier to hold and carry. It weighs less than 1.8 kg (4 pounds), and consists of a mechanical appendage made out of carbon fiber composite that has one end attached to a carbon fiber plate that fits inside an armor plate pocket and the other end attached to a Picatinny rail on top of the gun. It was designed to permit more accurate use of heavier weapons and reduce fatigue by displacing the weight of the weapon from the arms to the torso, and to mitigate weapon recoil. As of 2018, the Third Arm is a prototype and is still in the testing phase of its development.
History
The development of the Third Arm began in 2015 as a collaborative effort in ARL’s Human Research and Engineering Directorate (HRED) and Weapons & Research Materials Directorate (WMRD). The project was an attempt to improve the marksmanship of soldiers by finding ways that would make the use of heavier, more lethal firearms and larger bullets easier to manage.
The first prototype of was built in 2016 and first unveiled to the public in March 2017 at the Association of the United States Army (AUSA) conference in Huntsville, Alabama. A pilot study was conducted in summer 2017, where the prototype was tested with six soldiers who wore electromyography sensors that recorded muscle activity with and without the Third Arm. The results indicated that the device improved shooting accuracy and lessened muscle fatigue. A second prototype was constructed based on the soldiers’ feedback. Changes included the mounting location, the addition of an extendable hinge plate that adhered to different body types, and refinements to the design that made it easier for the wearer to dive into the prone shooting position.
Applications
The Third Arm can be used to completely take off the weight of heavy firearms such as the 7.5 kg (17-pound) M249 light machine gun or the 12.5 kg (27.6-pound) M240B general-purpose machine gun from the holder’s arms. By supporting the weapon’s weight, soldiers are capable of operating the firearm with one hand, leaving the other hand free for another task. It can be used to carry a breaching saw or a shield instead of a firearm. Testing has shown that the Third Arm provides immediate stabilization during movement, allowing for improved marksmanship.
See also
Aliens (film)
Affusto d'assalto/bari mount
Steadicam, similar concept
Sling (firearms)
Walking fire
Weapon mount
References
External links
US10393476B2 - Third Arm Weapon Interface System (TAWIS) patent
CN112665462A - Wearable weapon arm device of formula of double shooting formula mode patent
Military technology
Firearm components
Robotic manipulation | Third Arm Weapon Interface System | [
"Technology"
] | 601 | [
"Firearm components",
"Components"
] |
57,893,865 | https://en.wikipedia.org/wiki/Robotic%20magnetic%20navigation | Robotic magnetic navigation (RMN) (also called remote magnetic navigation) uses robotic technology to direct magnetic fields which control the movement of magnetic-tipped endovascular catheters into and through the chambers of the heart during cardiac catheterization procedures.
Devices
Because the human heart beats during ablation procedures, catheter stability can be affected by navigation technique. Magnetic fields created by RMN technology guide the tip of a catheter using a “pull” mechanism of action (as opposed to “push” with manual catheter navigation). Magnetic catheter navigation has been associated with greater catheter stability.
Medical use
Atrial fibrilation
As of 2015 there were two robotic catheterization systems on the market for atrial fibrilation; one of them used magnetic guidance.
After long-term follow up, RMN navigation has been associated with better procedural and clinical outcomes for AF ablation when compared with manual catheter navigation for cardiac ablation.
Ventricular tachycardia
RMN has been shown to be safe and effective for cardiac catheter ablation in various patient populations with ventricular tachycardia.
References
Medical technology | Robotic magnetic navigation | [
"Biology"
] | 241 | [
"Medical technology"
] |
57,896,281 | https://en.wikipedia.org/wiki/TXS%200506%2B056 | TXS 0506+056 is a very high energy blazar – a quasar with a relativistic jet pointing directly towards Earth – of BL Lac-type. With a redshift of 0.3365 ± 0.0010, it has a luminosity distance of about . Its approximate location on the sky is off the left shoulder of the constellation Orion. Discovered as a radio source in 1983, the blazar has since been observed across the entire electromagnetic spectrum.
TXS 0506+056 is the first known source of high energy astrophysical neutrinos, identified following the IceCube-170922A neutrino event in an early example of multi-messenger astronomy. The only astronomical sources previously observed by neutrino detectors were the Sun and supernova 1987A, which were detected decades earlier at much lower neutrino energies.
Observational history
The object has been detected by numerous astronomical surveys, so has numerous valid source designations. The most commonly used, TXS 0506+056, comes from its inclusion in the Texas Survey of radio sources (standard abbreviation TXS) and its approximate equatorial coordinates in the B1950 equinox used by that survey.
TXS 0506+056 was first discovered as a radio source in 1983. It was identified as an active galaxy in the 1990s, and a possible blazar in the early 2000s. By 2009 it was regarded as a confirmed blazar and catalogued as a BL Lac object. Gamma rays from TXS 0506+056 were detected by the EGRET and Fermi Gamma-ray Space Telescope missions.
Radio observations using very-long-baseline interferometry have shown apparent superluminal motion in the blazar's jet. TXS 0506+056 is one of the blazars regularly monitored by the OVRO 40 meter Telescope, so has an almost-continuous radio light curve recorded from 2008 onwards.
The gamma-ray flux from TXS 0506+056 is highly variable, by at least a factor of a thousand, but on average it is in the top 4% of brightest gamma-ray sources on the sky. It is also very bright in radio waves, in the top 1% of sources. Given its distance, this makes TXS 0506+056 one of the most intrinsically powerful BL Lac objects known, particularly in high-energy gamma rays.
Neutrino emission
On September 22, 2017, the IceCube Neutrino Observatory detected a high energy muon neutrino, dubbed IceCube-170922A. The neutrino carried an energy of ~290 tera–electronvolts (TeV); for comparison, the Large Hadron Collider can generate a maximum energy of 13 TeV. Within one minute of the neutrino detection, IceCube sent an automated alert to astronomers around the world with coordinates to search for a possible source.
A search of this region in the sky, 1.33 degrees across, yielded only one likely source: TXS 0506+056, a previously-known blazar, which was found to be in a flaring state of high gamma ray emission. It was subsequently observed at other wavelengths of light across the electromagnetic spectrum, including radio, infrared, optical, X-rays and gamma-rays. The detection of both neutrinos and light from the same object was an early example of multi-messenger astronomy.
A search of archived neutrino data from IceCube found evidence for an earlier flare of lower-energy neutrinos in 2014-2015 (a form of precovery), which supports identification of the blazar as a source of neutrinos. An independent analysis found no gamma-ray flare during this earlier period of neutrino emission, but supported its association with the blazar. The neutrinos emitted by TXS 0506+056 are six orders of magnitude higher in energy than those from any previously-identified astrophysical neutrino source.
The observations of high energy neutrinos and gamma-rays from this source imply that it is also a source of cosmic rays, because all three should be produced by the same physical processes, though no cosmic rays from TXS 0506+056 have been directly observed. In the blazar, a charged pion was produced by the interaction of a high-energy proton or nucleus (i.e. a cosmic ray) with the radiation field or with matter. The pion then decayed into a lepton and the neutrino. The neutrino interacts only weakly with matter, so it escaped the blazar. Upon reaching Earth, the neutrino interacted with the Antarctic ice to produce a muon, which was observed by the Cherenkov radiation it generated as it moved through the IceCube detector.
Analysis of 16 very long baseline radio array 15-GHz observations between 2009 and 2018 of TXS 0506+056 revealed the presence of a curved jet or potentially a collision of two jets, which could explain the 2014-2015 neutrino generation at the time of a low gamma-ray flux and indicate that TXS 0506+056 might be an atypical blazar.
In 2020, a study using MASTER global telescope network found that TXS 0506+056 was in an 'off' state in the optical spectrum 1 minute after the alert for IceCube-170922A event and switched back on 2 hours later. This would indicate that the blazar was in a state of neutrino efficiency.
See also
Messier 77 – a second neutrino source reported by IceCube in November 2022
SN 1987A#Neutrino emissions – a burst of neutrinos observed to come from a supernova
Neutrino astronomy
GW170817 – the first multi-messenger event involving gravitational waves; occurred five weeks before IceCube-170922A
References
External links
Frankfurt Quasar Monitoring: MG 0509+0541 with finding chart.
Aladin Lite view of Fermi data centered on TXS 0506+056
Astronomical X-ray sources
BL Lacertae objects
Orion (constellation)
Neutrino astronomy
Radio galaxies | TXS 0506+056 | [
"Astronomy"
] | 1,297 | [
"Orion (constellation)",
"Neutrino astronomy",
"Constellations",
"Astronomical X-ray sources",
"Astronomical objects",
"Astronomical sub-disciplines"
] |
57,897,954 | https://en.wikipedia.org/wiki/NGC%203841 | NGC 3841 is an elliptical or lenticular galaxy located about 300 million light-years away in the constellation Leo. It was discovered by astronomer John Herschel on March 25, 1827 is a member of the Leo Cluster.
On November 17, 2006 a type Ia supernova designated as SN 2006oq was found near NGC 3841. However it was not associated with the galaxy.
See also
List of NGC objects (3001–4000)
References
External links
3841
36469
Elliptical galaxies
Leo (constellation)
Leo Cluster
Lenticular galaxies
Astronomical objects discovered in 1827 | NGC 3841 | [
"Astronomy"
] | 115 | [
"Leo (constellation)",
"Constellations"
] |
57,899,033 | https://en.wikipedia.org/wiki/Breakthrough%20Laminar%20Aircraft%20Demonstrator%20in%20Europe | The Breakthrough Laminar Aircraft Demonstrator in Europe (BLADE) is an Airbus project within the European Clean Sky framework to flight-test experimental laminar-flow wing sections on an A340 from September 2017.
Design
Natural laminar flow is opposed to hybrid laminar flow artificially induced through hardware.
It is difficult to industrialise a wing smooth enough to sustain the laminar flow in operation, due to having very low design and manufacturing tolerances, leading-edge retractable slats, and fasteners, that is aerodynamically robust enough, and can withstand surface deformations and dirt, de-icing fluid, and rain-droplet contamination.
The metallic outboard section with a carbon fiber reinforced plastic upper laminar flow surface is isolated from the rest of the wing and has two ailerons on each side.
Its wing sweep is around 20° for a Mach 0.75 cruise, instead of 30° for a Mach 0.82–0.84 cruise.
Laminar flow is expected along 50% of chord length instead of just aft of the leading edge, halving the wing friction drag, reducing the overall aircraft drag by 8% and saving up to 5% in fuel on an 800nm (1,480km) sector.
Development
The demonstrator took off on 26 September, 2017.
In April 2018, after 66 flight hours, drag reduction is better than expected at 10% and laminar flow is more stable than anticipated, including when the wing twists and flexes.
Both wings with their carbon fibre upper sustainably generate the desired effect, while the carbon fibre left wing leading edge and metallic right wing leading edge have small differences in aerodynamic effects.
The aerodynamic benefits could be sustained at Mach 0.78 up from Mach 0.75 and next-generation single-aisles could use from the late 2020s.
Tests will continue until 2019 and will include wing contamination and a fixed Krüger flap.
Morphing flaps should be flight tested from May 2020.
References
Further reading
2010s international experimental aircraft
Aerodynamics
Air pollution organizations
Airbus A340
European Commission projects
European Union and science and technology
International aviation organizations
Pan-European trade and professional organizations
Research and development in Europe
Research projects | Breakthrough Laminar Aircraft Demonstrator in Europe | [
"Chemistry",
"Engineering"
] | 452 | [
"Aerospace engineering",
"Aerodynamics",
"Fluid dynamics"
] |
57,899,419 | https://en.wikipedia.org/wiki/Pup%20play | Pup play or puppy play is a form of fetishistic animal play where participants adopt a canine personality known as "pups", through apparel and dog-like behaviors.
Overview
Puppy play is defined as "a sociosexual activity wherein 1 or more participants take on the mannerisms, behavior, and attitudes of a dog – often facilitated by the wearing of specialist ‘gear’". This can include both physical apparel and behavioral traits, such as communicating via non-verbal cues such as growling or barking. Pup play culture is closely linked to the leather subculture and BDSM communities, with much of the apparel and accessories crafted from leather, rubber, latex, or neoprene. While the culture is categorized as a fetish, it can also serve as a social outlet for many individuals, particularly within the LGBTQ community.
Features
In puppy play, or pup play, at least one of the participants acts out canine mannerisms and behaviors. If there is a dominant role it can be taken by a "handler", "trainer", "master", or in the case of someone who also identifies as a pup, an "alpha". Not all "pups" or "dogs" are "alpha", some consider themselves "beta" or "omega", and as in the canine world hierarchy, "beta" can refer to someone who has both dominant and submissive or service oriented tendencies depending on the situation where "omega" generally indicates a more submissive, passive, service oriented and playful nature. Unlike other forms of animal roleplay, it is not uncommon for two or more pups to play together as equals, possibly fight for dominance, or play where one is clearly the "alpha".
Puppy play is often about being playful, mischievous, cheeky and instinctive. Many human puppies like to simplify their desires and motivations as they embrace the side of themselves that acts solely on instinct. A great deal of animal role play occurs socially. A group of like-minded pet-players will gather at events specifically organised for social pet play. At pup play events, for example, which occur all over the world, human puppies will act like bio puppies, relaxing, playing fetch, and interacting with human handlers.
In relation to other BDSM play, a "puppy" who is "unowned" or "uncollared" can be referred to as a "stray". Many pups use a headspace when getting into a roleplay scenario known as "pup space" which allows them to take on their puppy persona more easily. Other elements rooted in BDSM play involve bondage and restriction with collars, leashes, kneepads (for knee protection), harnesses, rubber suits, hoods (not needed but sometimes helps to assist with headspace and self identity) and mitts (for hand protection as well as finger usage restriction). Both sexual and non-sexual services are options that occur in the scene and should be discussed by the participants (pup / handler, beta / alpha, etc.) ahead of time so expectations are not misinterpreted. "Training" may take place in order to teach commands or tricks if both participants desire such interactions.
Demographics
According to Wignall et al. (2022), data was collected from a 2019 survey designed and organized by the Australian non-profit Nerdy Doggo. The survey gathered data from various social media platforms popular with pups, including Twitter, Facebook, Telegram, and WhatsApp. The data showed that homosexual males made up approximately 60.3% (442) of the sampled 733 participants, with 58.1% (426) of them aged 18–30 years, and the remaining 41.9% (307) being older than 30 years. Of the participants, 666 (90.9%) reported owning gear related to pup play, with 600 (81.9%) of those owning pup hoods.
Wignall et al. (2023) sampled 413 pup play practitioners from an international internet survey with the aim to "examine the occurrence of autistic traits and explore characteristics and social connections of people with autistic traits who engage in pup play". Participants' autistic traits were assessed using the Autism-spectrum quotient (short form). The survey found that the average score for autistic traits was 65.83, with a range from 29 to 100. Out of the 413 participants, 35.4% (146) scored above 70, which is considered a higher threshold for indicating stronger autistic traits. Additionally, 55.7% (230) of the participants scored 65 or above, which is considered a lower threshold for identifying autistic traits.
References
Gay culture
Sexual fetishism
Sexual roleplay
Sexology
Sexual attraction | Pup play | [
"Biology"
] | 990 | [
"Behavioural sciences",
"Behavior",
"Sexology"
] |
57,899,602 | https://en.wikipedia.org/wiki/National%20Documentation%20Centre%20%28Greece%29 | The National Documentation Centre (EKT; ) is a Greek public organization that promotes knowledge, research, innovation and digital transformation. It was established in 1980 with funding from the United Nations Development Programme with the aim to strengthen the collection and distribution of research-related material, and to ensure full accessibility to it. It has been designated as a National Scientific Infrastructure, a National Authority of the Hellenic Statistical System, and National Contact Point for European Research and Innovation Programmes. Since August 2019, it has been established as a discrete public-interest legal entity under private law, and is supervised by the Ministry of Digital Governance (Article 59 / Law 4623/2019). The management bodies of EKT are the Administrative Board and the Director who, since 2013, has been Dr. Evi Sachini.
Goals
EKT's institutional role is the collection, organisation, documentation, digital preservation, and dissemination of scientific, research and cultural information, content and data produced in Greece. EKT’s specific objectives, as stated on its official website, focus among others, on:
Ensuring the dissemination of the country's scientific output.
Meeting the needs of academia, policymakers and research and business communities for information and reliable data.
Increasing the digital scientific and cultural content that is available in a user-friendly form and with legitimate rights of use for different target groups
Promoting open access to publications and data in the academic and research communities.
Collaboration with academic libraries for the standardization in organizing and distributing metadata and digital scientific content.
Collaboration and joint actions with libraries, archives, museums, scientific and cultural institutions which produce and manage content, focusing on the establishment of common interoperability standards and the availability of metadata and digital content.
Providing specialized services to support the rapidly growing community of creative industries, start-ups and knowledge-intensive businesses.
Promoting and supporting technology transfer, innovation management and participation in European research and business networks of the academic, research and business communities.
General actions and areas of activity
EKT is active in many areas, strengthening the dissemination of existing and generated scientific and entrepreneurial knowledge with minimal restrictions ready to be reused in research, education, development, innovation and society. Specifically, EKT collects, documents and makes reliable digital scientific and cultural content available, measures and monitors the Greek Research, Technology, Development, Innovation ecosystem and supports businesses so that they can network, become outward-oriented and collaborate with the research community. It actively contributes actively in the national strategic planning Open Science and Open Access, while providing information on Open Access and Open Science issues through the openaccess.gr website. Since 1985, EKT has been legally appointed to establish, maintain and make available the National Archive of PhDTheses, which includes more than 44,000 doctoral dissertations (data: July 2020). EKT has cutting-edge technological infrastructure enabling high quality electronic services. In addition to its online services, EKT organizes and participates in workshops, conferences and exhibitions within Greece and abroad, while producing yearly publications, with a wide range of topics for Research, Innovation and Digital Content. Also, since 1996, it has been publishing the quarterly magazine 'Innovation, Research and Technology', presenting the most important developments in innovation, entrepreneurship, digital transformation, including EKT’s relevant actions, and search achievements and innovations of Greek researchers. EKT’s operations are funded by the Regular Budget, the Public Investment Programme, European and Co-financed Programmes and the provision of services.
EKT develops services in three areas of activity:
Digital content and services - eContent
In collaboration with reputable cultural and scientific organisations, EKT promotes the idea of a digital public space for culture and scientific knowledge produced in Greece. EKT has a comprehensive approach to organising and disseminating data about contemporary culture, cultural heritage and scientific output in the country. Central to its strategy is continuous data quality improvements, assuring interoperability of systems & data and openness. Through the aggregators SearchCulture.gr (reference 5) and OpenArchives.gr (reference 6) users have access to rich digital content and collections of authoritative organisations. Much of this activity involves best practice in documentation and semantic enrichment of metadata, in order to semantically link them and provide better search for queries made by different user communities. National content infrastructures, such as the National Archive of PhD Theses, the Social Sciences and Humanities Index, the National Hellenic Union Catalogue of Scientific Serials (ESKEP) (reference 7) and the bibliographic database BIBLIONET (reference 8), support researchers, scientists and society in general, in their search for reliable information. A number of public services, such as openABEKT (reference 9) and ePublishing (reference 10), have been developed to meet the specialised needs of organisations, publishers and information scientists. EKT's Digital Library of Science, Technology and Culture (reference 11) provides access to collections of international and Greek content, such as scientific journals books, databases, doctoral dissertations, and offers users personalised information services. Further information at: https://econtent.ekt.gr/
Indicators and statistics for research, technology, development and innovation - metricsEKT
EKT is at the forefront of statistical production and policy monitoring, making it the largest data provider on developments in the areas of research, innovation and entrepreneurship in Greece. Under its capacity as a National Authority of the Hellenic Statistical System, EKT collaborates with ELSTAT, Eurostat and OECD and produces the official statistics and indicators for Research, Technology, Development and Innovation (RDI). Also EKT produces and publishes a range of statistics and indicators on Greek scientific publications in international journals, on holders of doctoral degrees, on women in Research & Development and on research performance in European programmes. In addition, it conducts studies and issues publications that contribute to the mapping and understanding of the national research and innovation system. Finally, it collects data, produces indicators and research on young researchers, highlighting their results. EKT is an outward oriented organisation and actively participates in the international statistical community, taking part in scientific conferences and international committees, thus enriching the domestic public discourse with new aspects necessary for understanding innovation activities. Further information at: https://metrics.ekt.gr/
Services for networking, partnerships, growth - innovationEKT'
EKT plays a key role in informing the research and academic communities, in supporting businesses to effectively utilise European and public policies and financial instruments. Amongst its priorities are the connection between research and entrepreneurship, and the empowerment of top young researchers and entrepreneurs. With extensive experience as a National Contact Point for 11 areas in the European Horizon 2020 Research and Innovation Programme, and as the co-ordinator of Enterprise Europe Network-Hellas, EKT advises researchers and businesses in order to secure funding, seek international co-operation and strengthen their outward-orientation and potential. EKT as the EIT Health HUB co-ordinator for Greece acts as an accelerator for digital health and medtech startups and supports students in the KTI framework. EKT provides research teams and companies with valid and timely information on funding opportunities and provides advisory guidance for participation in research projects and collaboration for research, technology and business. It also helps to leverage research results by connecting businesses and research bodies. Finally, it seeks to create a virtual community of Greeks around the world, connecting them to the country, through the 'Knowledge and Partnership Bridges' initiative.
Notes
External links
Official site
openABEKT
EKT ePublishing
National Archive of PhD Theses
OpenArchives.gr
Searchculture.gr
Knowledge and Partnership Bridges
InnovationEKT (services related to H2020, Horizon Europe, Enterprise Europe Network, EIT Health, and more
1980 establishments in Greece
Science and technology in Greece
Archives in Greece
Greek digital libraries
Organizations based in Athens
Data and information organizations
Statistical organizations
Metrics
Computer networking | National Documentation Centre (Greece) | [
"Mathematics",
"Technology",
"Engineering"
] | 1,599 | [
"Computer networking",
"Metrics",
"Computer engineering",
"Quantity",
"Computer science",
"Data",
"Data and information organizations"
] |
57,899,689 | https://en.wikipedia.org/wiki/Gypenoside | Gypenosides are triterpenoid saponins and are the main active components of Gynostemma pentaphyllum, a climbing plant in the family Cucurbitaceae. They have been traditionally used in herbal medicine and have been shown to be effective in the treatment of cardiovascular diseases, although their mechanism of action is unknown.
Gypenoside A has the chemical formula C46H74O17.
References
Saponins | Gypenoside | [
"Chemistry"
] | 94 | [
"Biomolecules by chemical classification",
"Natural products",
"Saponins"
] |
71,787,137 | https://en.wikipedia.org/wiki/AE%20Ursae%20Majoris | AE Ursae Majoris is a star in the northern circumpolar constellation of Ursa Major, abbreviated AE UMa. It is a variable star that ranges in brightness from a peak apparent visual magnitude of 10.86 down to 11.52. The distance to this star is approximately 2,400 light years based on parallax measurements.
The variability of this star was announced by E. Geyer and associates in 1955. V. P. Tsesevich in 1973 found it to be a dwarf cepheid with a period of 0.086017 days, and he noticed it showed amplitude variations in the light curve. In 1974, B. Szeidl determined a secondary period of 0.066529 days, while P. Broglia and P. Conconi found a beat period of 0.294 days. It belonged to a group of high amplitude, double mode Delta Scuti variables that included SX Phoenicis, and by 1995 it was classified as a SX Phoenicis variable and a possible halo object. However, E. Hintz and associates in 1997 found strong evidence against this classification.
In 2001, the overtone pulsation period of this star was shown to change at the rate of . In addition, possible sudden jumps in the period have been observed, a property it has in common with VZ Cancri. With an estimated mass 1.8 times that of the Sun and an age of a billion years, it is an evolved star that has left the main sequence and is generating energy on a hydrogen-burning shell surrounding a helium core. The metallicity suggests it is a population I Delta Scuti variable. Currently it is crossing the Hertzsprung gap.
References
Further reading
A-type subgiants
Delta Scuti variables
SX Phoenicis variables
Hertzsprung gap
Ursa Major
047181
Ursae Majoris, AE | AE Ursae Majoris | [
"Astronomy"
] | 396 | [
"Ursa Major",
"Constellations"
] |
71,787,156 | https://en.wikipedia.org/wiki/Lorna%20Stewart | Lorna Kay Stewart is a retired Canadian computer scientist and discrete mathematician whose research concerns algorithms in graph theory and special classes of graphs, including cographs, permutation graphs, interval graphs, comparability graphs and their complements, well-covered graphs, and asteroidal triple-free graphs. She earned her Ph.D. in 1985 at the University of Toronto under the supervision of Derek Corneil, and is a professor emerita at the University of Alberta.
Selected publications
References
External links
Home page
Year of birth missing (living people)
Living people
Canadian computer scientists
Canadian mathematicians
Canadian women computer scientists
Canadian women mathematicians
Graph theorists
University of Toronto alumni
Academic staff of the University of Alberta | Lorna Stewart | [
"Mathematics"
] | 139 | [
"Mathematical relations",
"Graph theory",
"Graph theorists"
] |
71,787,666 | https://en.wikipedia.org/wiki/Bir%C5%BEai%20Forest | The Biržai Forest is a primaeval forest in Biržai District Municipality, Lithuania. With the area of 16,770 hectares, it is the tenth largest forest in terms of area in Lithuania. It is managed, with some other smaller forests, by the (Biržų miškų urėdija).
See also
Biržai Regional Park
References
Forests of Lithuania
Biržai District Municipality
Old-growth forests | Biržai Forest | [
"Biology"
] | 87 | [
"Old-growth forests",
"Ecosystems"
] |
71,788,377 | https://en.wikipedia.org/wiki/Ministry%20of%20Oil%20and%20Minerals%20%28Yemen%29 | Ministry of Oil and Minerals (Arabic: وزارة النفط والمعادن ) is a cabinet ministry of Yemen.
List of ministers
Saeed Sulaiman al-Shamasi (28 July 2022)
Abdulsalam Abdullah Baaboud (18 December 2020 – 28 July 2022)
Aws al-Awd (2017–2020)
Mohamed Abdullah Nahban (9 November 2014)
See also
Politics of Yemen
Ministry of Oil and Minerals (in Arabic)
References
Government ministries of Yemen | Ministry of Oil and Minerals (Yemen) | [
"Engineering"
] | 110 | [
"Energy organizations",
"Energy ministries"
] |
71,788,544 | https://en.wikipedia.org/wiki/Silvana%20Konermann | Silvana Konermann is a Swiss-American bioengineer and neuroscientist whose research focuses on CRISPR, genome engineering, transcription and epigenetics, and Alzheimer's disease. She is an assistant professor of biochemistry at Stanford University, as well as co-founder and executive director of the Arc Institute in Palo Alto, California.
Biography
Konermann attended Sächsisches Landesgymnasium Sankt Afra zu Meißen in Saxony, Germany, before matriculating in 2006 at ETH Zurich, where she completed her bachelor of science degree in neurobiology in three years.
She then moved to the United States and worked in the lab of Carlos Lois before entering the doctoral program in neuroscience at the Massachusetts Institute of Technology, receiving her Ph.D. in 2016 working in Feng Zhang's group. Since 2017, she has been an HHMI (Howard Hughes Medical Institute) Hanna H. Gray Fellow. She has also been a CZ Biohub Investigator and a postdoctoral fellow at the Salk Institute for Biological Studies and the University of California, Berkeley working with Patrick Hsu. In 2019, she joined Stanford as an assistant professor.
Konermann's research uses genome engineering technologies to investigate the genetic and molecular drivers of Alzheimer’s disease risk.
21546 Konermann, a minor planet, was named after her, in honor of her 2006 second-place finish in the Intel International Science and Engineering Fair. At that time she was a senior at Sankt Afra in Meissen, Germany.
In June 2022, Konermann married Irish-American tech billionaire Patrick Collison, the co-founder and CEO of Stripe, with whom she co-founded Fast Grants and later the Arc Institute. Konermann met Collison during the 2004 EU Young Scientist competition.
References
External links
Living people
Year of birth missing (living people)
Place of birth missing (living people)
Stanford University faculty
American people of Swiss descent
Biochemical engineering | Silvana Konermann | [
"Chemistry",
"Engineering",
"Biology"
] | 405 | [
"Biochemistry",
"Chemical engineering",
"Biological engineering",
"Biochemical engineering"
] |
71,788,622 | https://en.wikipedia.org/wiki/American%20Board%20of%20Applied%20Toxicology | The American Board of Applied Toxicology (ABAT) was established in 1985 as a standing committee by the American Academy of Clinical Toxicology. The board functions to recognize and credential clinical toxicologists who have demonstrated competence in the management of toxicity related to poisoning, overdose, chemical exposure, envenomation, or environmental exposures. Candidates for board certification are health professionals (pharmacists, nurses, PhD biomedical scientists) with minimum perquisite experience in poisoning and overdose management as well as satisfactory experience in other core areas such as toxicology research, public health, and outreach. The ABAT establishes minimum competency for clinical toxicologists (professionals who manage poisoning, overdose, and chemical toxicity) via administering examinations and maintaining certification renewal of diplomates. Successfully passing the ABAT board certification exam provides the taker a designation of Diplomate of the American Board of Applied Toxicology (DABAT). A DABAT designation privileges the clinical toxicologist to provide medical back up and consultation on poisoning, drug overdoses, or toxicity, often via poison centers. The DABAT designation also has legal implication in allowing credentialed toxicologists to manage a poison center in the United States. Credentialed DABAT members must recertify every 5 years via an application demonstrating continued competence and activity in clinical toxicology.
History
In 1974 the American Academy of Clinical Toxicology established the American Board of Medical Toxicology to recognize physicians competent in the management of poisoning and drug overdose in the United States. Eleven years later in 1985 the American Board of Applied Toxicology was created. The inaugural ABAT examination was provided in 1987 for the first ABAT diplomates. The ABAT board is composed of ABAT diplomates who have been elected to the board of directors. The American Board of Medical Toxicology established by AACT later became the American College of Medical Toxicology once officially recognized as a subspecialty and is responsible for governing board certification status of physician toxicologists. Veterinarian toxicologists are certified via the American Board of Veterinary Toxicology. PhD research toxicologists (Non clinical toxicologists, i.e., those not directly participating in therapeutic management of patients) are certified via the American Board of Toxicology (ABT). ABAT encompasses certification for all clinical non-physician or veterinarian toxicologists.
Credentialing
Candidates for ABAT examination must meet educational (doctoral degree in health sciences or baccalaureate with sufficient experience) and experiential requirements (post graduate residency or fellowship training, or equivalent work experience). Additionally candidates must have cared for a minimum number of human patients experiencing toxic exposures as well as satisfy criteria in teaching, publication of peer-reviewed scientific literature, research, and outreach to qualify to sit for the ABAT exam.
Activities
Managing and clinically supervising poison centers and staff
Consultation on poisoning, drug overdose, or health risk assessment
Medicolegal and forensic expert witness consultation
Poisoning epidemiology research
Clinical research and creation of poisoning management guidelines
Bed side patient management in the acute care and emergency medicine setting
References
Medical associations based in the United States
Medical and health organizations based in Virginia
Toxicology organizations | American Board of Applied Toxicology | [
"Environmental_science"
] | 634 | [
"Toxicology organizations",
"Toxicology"
] |
71,790,076 | https://en.wikipedia.org/wiki/Ordinal%20priority%20approach | Ordinal priority approach (OPA) is a multiple-criteria decision analysis method that aids in solving the group decision-making problems based on preference relations.
Description
Various methods have been proposed to solve multi-criteria decision-making problems. The basis of methods such as analytic hierarchy process and analytic network process is pairwise comparison matrix. The advantages and disadvantages of the pairwise comparison matrix were discussed by Munier and Hontoria in their book. In recent years, the OPA method was proposed to solve the multi-criteria decision-making problems based on the ordinal data instead of using the pairwise comparison matrix. The OPA method is a major part of Dr. Amin Mahmoudi's PhD thesis from the Southeast University of China.
This method uses linear programming approach to compute the weights of experts, criteria, and alternatives simultaneously. The main reason for using ordinal data in the OPA method is the accessibility and accuracy of the ordinal data compared with exact ratios used in group decision-making problems involved with humans.
In real-world situations, the experts might not have enough knowledge regarding one alternative or criterion. In this case, the input data of the problem is incomplete, which needs to be incorporated into the linear programming of the OPA. To handle the incomplete input data in the OPA method, the constraints related to the criteria or alternatives should be removed from the OPA linear-programming model.
Various types of data normalization methods have been employed in multi-criteria decision-making methods in recent years. Palczewski and Sałabun showed that using various data normalization methods can change the final ranks of the multi-criteria decision-making methods. Javed and colleagues showed that a multiple-criteria decision-making problem can be solved by avoiding the data normalization. There is no need to normalize the preference relations and thus, the OPA method does not require data normalization.
The OPA method
The OPA model is a linear programming model, which can be solved using a simplex algorithm. The steps of this method are as follows:
Step 1: Identifying the experts and determining the preference of experts based on their working experience, educational qualification, etc.
Step 2: identifying the criteria and determining the preference of the criteria by each expert.
Step 3: identifying the alternatives and determining the preference of the alternatives in each criterion by each expert.
Step 4: Constructing the following linear programming model and solving it by an appropriate optimization software such as LINGO, GAMS, MATLAB, etc.
In the above model, represents the rank of expert , represents the rank of criterion , represents the rank of alternative , and represents the weight of alternative in criterion by expert .
After solving the OPA linear programming model, the weight of each alternative is calculated by the following equation:
The weight of each criterion is calculated by the following equation:
And the weight of each expert is calculated by the following equation:
Example
Suppose that we are going to investigate the issue of buying a house. There are two experts in this decision problem. Also, there are two criteria called cost (c), and construction quality (q) for buying the house. On the other hand, there are three houses (h1, h2, h3) for purchasing. The first expert (x) has three years of working experience and the second expert (y) has two years of working experience. The structure of the problem is shown in the figure.
Step 1: The first expert (x) has more experience than expert (y), hence x > y.
Step 2: The criteria and their preference are summarized in the following table:
Step 3: The alternatives and their preference are summarized in the following table:
Step 4: The OPA linear programming model is formed based on the input data as follows:
After solving the above model using optimization software, the weights of experts, criteria and alternatives are obtained as follows:
Therefore, House 1 (h1) is considered as the best alternative. Moreover, we can understand that criterion cost (c) is more important than criterion construction quality (q). Also, based on the experts' weights, we can understand that expert (x) has a higher impact on final selection compared with expert (y).
Applications
The applications of the OPA method in various field of studies are summarized as follows:
Agriculture, manufacturing, services
Manufacturing supply chain
Production strategies
Production scheduling
Automotive industry
Community service demand
Construction industry
Construction sub-contracting
Sustainable construction
Project management
Energy and environment
Natural resource extraction
Solar and wind energies
Low-carbon technologies
Electrification and emissions
Circular economy
Healthcare
COVID-19
Healthcare supply chain
Community services
Information technology
Metaverse
Autonomous vehicles
Process control
Electric vehicles
Blockchain
Technology demand
Transportation
Supply chain management
Transportation planning
Traffic control
Road maintenance
Extensions
Several extensions of the OPA method are listed as follows:
Grey ordinal priority approach (OPA-G)
Fuzzy ordinal priority approach (OPA-F)
Interval ordinal priority approach
Strict and weak OPA
Ordinal priority approach under picture fuzzy sets (OPA-P)
Confidence level measurement in the OPA
Neutrosophic ordinal priority approach (OPA-N)
Rough ordinal priority approach
Robust ordinal priority spproach (OPA-R)
Hybrid OPA–Fuzzy EDAS
Hybrid DEA-OPA model
Hybrid MULTIMOORA-OPA
Group-weighted ordinal priority approach (GWOPA)
Software
The following non-profit tools are available to solve the MCDM problems using the OPA method:
Web-based solver
Excel-based solver
Lingo-based solver
Matlab-based solver
References
Multiple-criteria decision analysis
Decision analysis
Management systems
Mathematical optimization | Ordinal priority approach | [
"Mathematics"
] | 1,157 | [
"Mathematical optimization",
"Mathematical analysis"
] |
71,794,818 | https://en.wikipedia.org/wiki/HD%2030669 | HD 30669 is a yellowish-orange hued star located in the southern constellation Caelum, the chisel. It has an apparent magnitude of 9.11, making it readily visible in small telescopes but not to the naked eye. The object is relatively close at a distance of 188 light years, based on parallax measurements from Gaia DR3. Its distance from the Solar System is rapidly increasing, having a heliocentric radial velocity of .
Characteristics
HD 30669 has a stellar classification of G8/K0 V — a main sequence star with the characteristics of a star with a class of G8 and K0. It has alternatively been given a class of G9 V. It has 92% the mass of the Sun and 91% its radius. The object radiates 59.7% the luminosity of the Sun from its photosphere at an effective temperature of from its photosphere. Like most planetary hosts, HD 30669 is metal enriched, having a metallicity 35% above solar levels. The star is extremely chromopsherically inactive and is estimated to be billion years old.
Planetary System
In 2015, C. Motou and colleagues discovered a long period exoplanet orbiting the star during a HARPS survey. It has nearly half the mass of Jupiter and it takes over years to revolve HD 30669 in a slightly eccentric orbit.
References
G-type main-sequence stars
K-type main-sequence stars
Planetary systems with one confirmed planet
Caelum
030669
022320
CD-28 01759 | HD 30669 | [
"Astronomy"
] | 325 | [
"Caelum",
"Constellations"
] |
71,795,180 | https://en.wikipedia.org/wiki/Alison%20Tomlin | Alison Sarah Tomlin is a British physical chemist and applied mathematician whose research involves building detailed mathematical models of combustion, including uncertainty quantification for those models. She is a professor in the School of Chemical and Process Engineering at the University of Leeds, where she heads the Clean Combustion Research Group.
Education and career
Tomlin was a student of mathematics and of the history of science and philosophy of science at the University of Leeds, where she earned a combined bachelor's degree in those topics in 1987. She continued at Leeds as a graduate student in physical chemistry, completing her dissertation Bifurcation analysis for non-linear chemical kinetics in 1990.
After earning her doctorate, and performing post-doctoral research at Leeds and Princeton University, she returned to Leeds as a lecturer in the Department of Fuel and Energy in 1994.
Book
With Tamás Turányi, Tomlin is coauthor of the book Analysis of Kinetic Reaction Mechanisms (Springer, 2014).
Recognition
A paper coauthored by Tomlin won the 1992 Sugden Award of The Combustion Institute. Tomlin was elected to the inaugural 2018 class of Fellows of The Combustion Institute, "for innovative research on the development and application of mechanism reduction, sensitivity analysis and uncertainty quantification in combustion models".
References
External links
Year of birth missing (living people)
Living people
British chemists
British women chemists
British mathematicians
British women mathematicians
Physical chemists
British applied mathematicians
Academics of the University of Leeds
Fellows of the Combustion Institute | Alison Tomlin | [
"Chemistry"
] | 296 | [
"Fellows of the Combustion Institute",
"Combustion",
"Physical chemists"
] |
71,795,209 | https://en.wikipedia.org/wiki/C.%20Hart%20Merriam%20Award | The C. Hart Merriam Award is given annually by the American Society of Mammalogists for "outstanding research in mammalogy".
The Merriam Award was established in 1974. Before 1996 the award was given for "outstanding contributions to mammalogy through research, teaching, and service". The award is named in honor of C. Hart Merriam (1855–1942). He was not only a founding member of the American Society of Mammalogists and a physician with an M.D. from Columbia University, but also "naturalist, ethnologist, explorer, scholar, lecturer, author, personal friend of Presidents ..."
References
Biology awards
Awards established in 1974
American Society of Mammalogists | C. Hart Merriam Award | [
"Technology"
] | 144 | [
"Science and technology awards",
"Biology awards"
] |
71,796,090 | https://en.wikipedia.org/wiki/Ephemeral%20architecture | Ephemeral architecture is the art or technique of designing and building structures that are transient, that last only a short time. Ephemeral art has been a constant in the history of architecture, although a distinction must be made between constructions conceived for temporary use and those that, despite being built with durability in mind, have a brief expiration due to various factors, especially the poor quality of the materials (wood, adobe, plaster, cardboard, textiles), in cultures that would not have sufficiently developed solid construction systems.
Ephemeral architecture was usually used for celebrations and festivals of all kinds, as scenography or theatrical scenery for a specific event, which was dismantled after the event. It has existed since ancient art—it is at the origin of forms such as the triumphal arch, whose ephemeral model was fixed in permanent constructions during the Roman Empire—and it was very common in European courts during the Renaissance and especially in the Baroque.
Despite its circumstantial character, the ephemeral has been a recurrent and relevant architecture. From Baroque scenographies to contemporary installations, each ephemeral period has given shape to its idea of celebration and has materialized it with the technique available at the time. Today the ephemeral continues to fulfill these playful and experimental functions, but it also aspires to channel new ideas about public space and social participation, halfway between the city and nature.
Classification
In the social context there are various ways of including ephemeral architecture: for specific events (traditional ephemeral architecture), as a way of life (nomadic architecture), as a requirement of a society that reveres change (obsolescent architecture), and as a necessity (emergency architecture).
Traditional ephemeral architecture
The architecture that is ephemeral because of its "eventuality".
Ancient period
There are few documents of constructions designed with an ephemeral duration, on the contrary, both Egyptian architecture and Greek and Roman stand out for their monumentality and the long-lasting eagerness of their constructions, especially the religious ones. The ephemeral constructions were especially used for public ceremonies and celebrations of military victories, or for festivities related to kings and emperors. Thus, there is a valuable testimony of a pavilion erected by Ptolemy II of Egypt to celebrate a banquet, reported by Athenaeus:
Early modern period, Renaissance and Baroque
The splendor of ephemeral architecture was produced in the Early Modern Period, in the Renaissance and—especially— the Baroque, eras of consolidation of the absolute monarchy, when European monarchs sought to elevate their figure above that of their subjects, resorting to all kinds of propagandistic and exalting acts of their power, in political and religious ceremonies or celebrations of a playful nature, which showed the magnificence of their government. One of the most frequent resources were the thriumphal arches, erected for any act such as military celebrations, royal weddings or visits of the monarch to various cities. There are several testimonies in this regard, such as the triumphal arch at the Porte Saint-Denis for the entrance of Enrique II in Paris in 1549, the arch at the Pont Nôtre-Dame for the entrance of Charles IX in Paris in 1571, the triumphal arch of Maximilian I designed by Dürer in 1513, the triumphal arch for the entrance of Charles V in Bruges in 1515, the arch for the entrance of Prince Philip (future Philip II of Spain) in Ghent in 1549, etc.
During the Baroque, the ornamental—contrived and ornate character of the art of this time conveyed a transitory sense of life—related to the memento mori, the ephemeral value of riches in the face of the inevitability of death, in parallel to the pictorial genre of the vanitas. This sentiment led to a vitalist appreciation of the fleetingness of the instant, to enjoy the light moments of relaxation that life offers, or the celebrations and solemn acts. Thus, births, weddings, deaths, religious ceremonies, royal coronations and other recreational or ceremonial events were dressed with pomp and artifice of a scenography character, where great assemblies were elaborated that agglutinated architecture and decorations to provide an eloquent magnificence to any celebration, which became a spectacle of almost catartic character, where the illusory element, the attenuation of the border between reality and fantasy took on special relevance.
Baroque art sought the creation of an alternative reality through fiction and illusion, resorting to foreshortening and illusionist perspective, a tendency that had its maximum expression in festivities, the playful celebration, where buildings such as churches or palaces, or a neighborhood or an entire city, became theaters of life, in scenarios where reality and illusion were mixed, where the senses were subverted to deception and artifice. The Counter-Reformationist Church played a special role, seeking to show its superiority over the Protestant Churches with pomp and pageantry, through events such as solemn mass, canonizations, jubilees, processions or papal investitures. But just as lavish were the celebrations of the monarchy and the aristocracy, with events such as coronations, royal weddings and births, funerals, ambassador visits, any event that allowed the monarch to display his power to the admiration of the people. Baroque festivities involved a conjugation of all the arts, from architecture and the plastic arts to poetry, music, dance, theater, pyrotechnics, floral arrangements, water games, etc. Architects such as Bernini or Pietro da Cortona, or Alonso Cano and Sebastián Herrera Barnuevo in Spain, contributed their talent to such events, designing structures, choreographys, lighting and other elements, which often served them as a testing ground for future more serious endeavors. The baldachin for the canonization of Saint Elizabeth of Portugal thus served Bernini for his future design of St. Peter's baldachin, and Carlo Rainaldi's quarantore (sacred theater of the Jesuits) was a model of the church of Santa Maria in Campitelli.
Contemporary period
In the Contemporary Period the phenomenon of the universal exhibitions— trade fairs held in cities all over the world to showcase scientific, technological and cultural advances to the population, and which became true mass spectacles and great advertising showcases for companies or countries that promoted their products—is worth mentioning. These exhibitions were held in enclosures where each country or company built a pavilion to promote itself, which were buildings or structures conceived in an ephemeral way to last only as long as the exhibition lasted. However, many of these constructions were preserved due to their success or the originality of their design, becoming a testing ground and promotion of the work of many architects. These exhibitions saw the first experiments with new typologies and materials characteristic of contemporary architecture, such as construction with concrete, iron and glass, or the important development of interior design, especially fostered by modernism. The first universal exhibition took place in London in 1851, being famous for the Crystal Palace designed by Joseph Paxton, a large glass palace with iron structure, which despite being preserved was destroyed by fire in 1937. From then until now there have been numerous exhibitions, many of which have revealed great architectural achievements, such as the Exposition Universelle of 1889, when the Eiffel Tower was built; the Barcelona International Exposition, which produced the German Pavilion by Ludwig Mies van der Rohe; the Brussels World's Fair, which produced the Atomium, by André Waterkeyn; the Seattle World's Fair, famous for the Space Needle; the International and Universal Exposition, with the US Pavilion in the form of a geodesic dome, by Buckminster Fuller; that of Sevilla '92, which bequeathed a theme park (Isla Mágica) and several office and technological development buildings (Cartuja 93); or that of Lisbon 1998, which legacy was the Oceanarium.
Finally, it is worth mentioning the boom since the mid-20th century in ice architecture, especially in the Nordic countries—as is logical given the special climatic circumstances that require this type of construction—where various types of ice buildings have begun to proliferate, such as hotels, museums, palaces and other structures generally conceived for public use and for recreational or cultural purposes. These constructions are based on traditional structures such as the igloo, the typical dwelling of the Inuit, but have evolved by incorporating all the theoretical and technical advances of modern architecture. Among other buildings made of ice, the Icehotel in Jukkasjärvi—built in 1990 on a provisional basis and maintained thanks to the success of the initiative, being redecorated every year with the participation of various architects, artists and students of various disciplines—is worth mentioning.
Except in the case of ice architecture, which hosts functions usually reserved for traditional architecture and needs to be preserved to survive, the construction methods used for this type of ephemeral architecture, as well as the materials, do not differ much from those used in traditional architecture. This and the fact that the societies in which it was developed were prone to venerate monumentality, and the success of some of the constructions of the universal exhibitions, meant that many of these buildings were finally preserved. Nowadays, the architecture that can best be compared to this type of event constructions are exhibitions (in museums, on the street, etc.) and cinematographic or theatrical scenographys. It is worth mentioning the relationship of ephemeral architecture with citizen cartography, and its relationship with the decision-making power of the user, who becomes the architect of his part of the space on some occasions. It can happen that specific parts of a building are movable, to configure a space in a momentary way in which everyone can adapt the conditions to the most suitable for himself.
Nomadic architecture
Portable domestic architecture that is ephemeral because of its "translationality". Architecture, in its origin, was born being ephemeral and to this day certain tribes continue with this lifestyle. There are theoretical projects that transfer this concept to the city, such as the New Babylon, developed from 1948 by Constant Nieuwenhuys. A utopia on a planetary scale, which advocates a return to nomadic origins thanks to the improvement of the machine, which frees the human being from his tasks (food production, etc.), and in this way a new evolution of the human being appears, the homo ludens who, freed from his occupations, can devote himself to art and happiness. For this achievement the world must be conceived from the freedom of choices and therefore of movements.
L'Architecture Mobile (1958) by Yona Friedman and the Plug-in-City (1964) by Archigram are also examples of the megastructures approach to this type of utopian cities. The cycle closes. If the human being becomes sedentary because he discovers the benefits of cultivation, after millennia machines free him from such a chore, so he can put his house back in his backpack and travel the world.
Obsolescent architecture
Architecture that is ephemeral because of its " temporariness". Architectural types that until now had always been conceived to remain, such as the house, are now thought to be dismembered and their pieces reused. It is the inheritance of the industrial society that allows us an architecture of prefabricated dwellings. As Sigfried Giedion explained at the First Congress of the CIAM:
Unlike nomadic architecture, the structure of the world maintains its sedentary nature, but the elements that we find within it are projected to change at a faster rate every day: the latest generation of cell phones, fashionable clothes, fast food, etc. These are terms that have settled in the collective unconscious and induce us to enhance the value of change and speed. It is positive, within this way of conceiving times of use, that a rising value is also ecology, since the reuse of these obsolete pieces is the antidote against landfills. There is a prevailing trivialization in many social aspects with the dominance of the ephemeral, the disposable. We are not only tolerant but enthusiastic about garbage-jobs, garbage-companies, garbage-stores, garbage-furniture, garbage-houses, garbage-families, garbage-programs and garbage-books. This strategy goes through the elimination of the qualities of things. In the words of José Luis Pardo:
Emergency architecture
Architecture that is ephemeral because of its "economy of resources". Based on immediate constructions, the fundamental premise is the rapid response required for its construction. That it will lose its use, be dismembered or change its place is of no interest. The important thing is to solve a specific need at a specific time, in the simplest way. It can be related to moments of natural catastrophes, as in the case of the Paper House by Shigeru Ban (1995) to provide a temporary housing for several victims of the Kobe earthquake; or with social sectors with few resources who want to provide them with a better quality of life. The latter case is more related to self-construction as a liberation from the bonds of capitalism, the construction of a greater solidarity among men, a condition of life in harmony with nature, and the feeling of being architects of a new beginning. The Rural Studio in Alabama and the Ciudad abierta de Ritoque (Valparaíso) are examples of this field of architectural experimentation.
Principles
Temporariness. Life, nowadays, is unpredictable. "Everyone changes places when they want to. Life is an endless journey through a world that transforms so rapidly that each time seems different." Ephemeral architecture is meant to respond to a specific act and can be dismantled after it has responded to that act. It can always be returned to the origin, unlike permanent constructions, in which the site remains conditioned.
Flexibility. The world changes constantly and at an ever-increasing speed. This type of architecture adapts quickly to the needs of the place. It can be constantly re-modeled, as needs change. The permeability of this architecture allows it to be assembled and disassembled by the users themselves. Nowadays any country or city is susceptible to encounter different emergency situations: situations derived from extreme meteorological phenomena, pandemics or moments in which political, military or civil disturbance factors intervene. In this sense, ephemeral architecture has an important task to solve to provide temporary shelters and shelters for victims of any kind, showing its most supportive character.
Innovation. It is about creating an architecture with innovative solutions in terms of miniaturization, self-construction and new materials. It has been reflected above all in emergency solutions either by wars or natural disasters. Conditions such as lightness, economy, speed and simplicity of assembly and disassembly, storage, sustainability, minimal, collective, transportable, reusable, prefabrication, and so on, require using the most innovative aspect of the architectural research.
Low cost. Concept generalized in the 60's with the fast food chains. In this consumer society, "low cost" companies of services, communications, industrial, technological, automotive and even airlines have appeared in all media. In the ephemeral architecture, low cost is one of the priority concepts that allows and motivates rapid operations to experiment, investigate and propose models and construction methods that are more advanced and visionary than those that traditional architecture allows us.
Economy of resources. This type of architecture adapts economically to the needs of the place. It takes into account the existing, either by nearby materials, or by taking into account the environment. Non-permanent architecture should not be exempt from its surroundings. The structural design must be the most appropriate to optimize resources.
Waste management. There are many economic problems and social problems that make us change the way of doing things. Nowadays, many believe that architecture should optimize resources and be low cost. This can be achieved by using recycled and recyclable materials, with reversible constructions. Once the building is no longer needed the materials can be returned to the company or reused for another construction, avoiding debris.
Do it yourself. Reversible self-buildings where users can decide what divisions and connections they want to make according to the use they need. It's a counterculture movement transferable to any area of daily life. Although it is also associated with anti-capitalist movements, by rejecting the idea of always buying from others things that one can create or manufacture. From the 1950s, the ability of each person to build his own house is made available to society, supported by the emergence of new materials such as plastics, which are characterized by their lightness and ease of transport, as well as making it possible to simplify the joining of different parts. Each person is the owner of their own environment, their own habitat. It is possible for the individual to become a contemporary nomad. Moreover, the user is the one who decides whether it works and must remain or whether it has finished its task.
Main authors
AntFarm
At the end of the 60s in the United States, AntFarm, a collective of architects, philosophers, filmmakers and artists arose that produced numerous performances, audiovisuals, collections of slides such as the enviro-images, television programs clandestine Top Value Television, inflatable architecture manuals like the Inflatocookbook, manifestos like the Nomadic Cowboy, or bound books like Reality, all with the aim of proposing new environments for a new way of life. A proposal with different mobile, inflatable, mechanical and technological elements that produce the necessary effects to make any support habitable with a vital, alternative, nomadic, utopian and experimental architecture, as he believes that "today's ambiguous society forces static patterns of life."
Archigram
Founded in 1962 by Warren Chalk, Peter Cook, Dennis Crompton, David Greene, Rom Herrom and Michael Webb, Archigram made a series of technological, futuristic and utopian proposals that bet on an ephemeral architecture destined to be consumed like any other product of society.
Future Systems
Based in England and founded by Jan Kaplický and Amanda Levete, Future Systems propose three technological, mobile, transformable, autonomous, sustainable, capsule, prefabricated, lightweight houses, using solar energy and wind energy. On the one hand, they could be understood as a revision and updating of the fundamental aspects raised from Buckminster Fuller to the generation of the masters of the 60s with whom Kaplicky and Levete were trained, and on the other hand, as visionaries of the world to come from the 21st century.
Shigeru Ban
Shigeru Ban manages to develop an emergency architecture from the social responsibility of the architect through experimentation and new (old) materials, the low cost, the temporal dimension, the low tech, the existing, the structural design, the waste management, the struggle with regulations, the commitment, participation, flexibility and the rejection of media architecture. Shigeru's houses are designed to be constantly remodeled, as are the needs. They are easy to build, the users themselves can do it.
Santiago Cirugeda
Santiago Cirugeda is one of the most innovative architects of the Spanish urban scene. His proposals on issues of occupation and resistance have given him international recognition in the field of guerrilla architecture. With his project Recetas Urbanas, he provides legal advice. He makes projects that reflect the idea of ephemeral architecture, these take into account the needs of the individual, the area where it is located and the circumstances of the moment. He defines an economic project, which adapts to demand and can even be self-built. He believes in non-permanent architecture, so many of his projects can be dismantled once it loses the utility for which it was created. In the documentary Spanish Dream, Cirugeda explains his way of understanding architecture:I have no interest in making architecture that lasts 300 years, but to make an architecture that serves temporary states because there are situations in the city that are developed by people who occasionally, for years, will work there or live there.
Remarkable works
Endless House. Frederick John Kiesler, 1924
For more than 30 years, the Viennese architect F. J. Kiessler, researched, speculated and experimented in an indeterminate, transformable, self-built, self-supporting, versatile, infinite, mutable and ergonomic architecture. The Endless House project, where the author explored the architectural possibilities of spaces in infinite development, capable of adapting to the changing conditions of the environment, never constant, always evolving, with a biomorphic configuration. The architecture "infinite as the human being, without beginning or end".
Detachable house for beach. GATCPAC, 1932
A type of wooden, minimal, self-built, demountable house for the vacation period in Catalonia. The whole house must be manageable: volume, weight, surface and reduced cost. The house can be expandable and is supplied with the indispensable furniture. It is intended to live in harmony with the landscape and nature without damaging the natural environment.
Maisons a Portiques. Charlotte Perriand and Le Corbusier, 1945
Together with Jean Prouvé, they designed and produced 400 removable pavilions as temporary housing for casualties after the liberation of France during the Second World War known as Maisons a Portiques. No element had to exceed 100 kilograms or measure more than 4 meters to meet the idea of quick and simple assembly, without technical aids, which could be transported in one go on a truck. The joints and connections had to be free of tension, even in the case of technical deformation; the facades had to be made up of interchangeable elements.
Village in cardboard. Guy Rottier, 1960
He proposes new and unprecedented architectures, corresponding to another way of living, combined with the new materials that were beginning to invade the construction market. His proposals deal with the architecture of camouflage, evolutionary, solar, ephemeral, vacation, recovery, etc. In his Village in Cardboard he proposes a vacation village in cardboard cells without doors or windows. All the space is public and does not offer "comfort". The roofs will be generated by the users with the aim that the vacationers are active, relate and communicate with others. The houses would be burned down at the end of the vacation.
Plug in city. Archigram, 1962–1966
A megastructure that had no buildings, just a large frame into which housing or service capsules could be fitted in the form of cells or standardized components. Each element had a durability; the base tubular structure 40 years, in the capsules it varies according to its program, from 6 months for a commercial space, to 5–8 years for bedrooms and living rooms. At the top an inflatable balloon is activated in bad weather.
Living Pod. David Greene, Archigram, 1966
It is a habitat-capsule that can be inserted inside an urban structure called plug-in, or it can be transported and perched on any natural landscape. A hybrid architecture, hermetic, small, comfortable and technological, constituted by the space itself and by the machines connected to it: "The house is an apparatus to be transported with itself, the city is a machine to which you connect." Although comparable to a capsule, the Living Pod does not have autonomy, that is why in 1969 he proposed the Logplug-Rockplug. Real simulations of logs and rocks that serve to hide service points for semi-autonomous living containers. They go unnoticed, perfectly adapted to the landscape and bring to any environment a high degree of technological support without detracting from the natural beauty.
Peanut. Future Systems, 1984
Rural shelter that mounts on a standard articulated hydraulic boom. The unit is for two people, can move on air, land and water according to purpose, activity or time. It is a kinetic response to life, allowing the inhabitants to control the appearance or orientation of the capsule according to mood, activity and time, leaving behind the fixed viewpoint of static dwellings.
Pao 1 and 2 of the nomadic girls of Tokyo. Toyo Ito, 1989
A project from the mid-1980s, consisting of a concept of a house scattered all over the city, where life goes by while using the fragments of the city space as a collage. For it, the living room is the café-bar and the theater, the dining room is the restaurant, the closet is the boutique, and the garden is the sports club.
Casa Básica. Martín Ruiz de Azúa, 1999
Proposal that aims to demonstrate that the habitat can be understood in a more essential and reasonable way, keeping a more direct relationship with the environment. An almost immaterial volume that swells from the heat of our own body or the sun, so versatile that it protects from cold and heat, so light that it floats.
Pink Project. Graph Architects, 2008
Produced by the Make It Right Foundation. It was conceived as an informative-commemorative tool to raise awareness and activate individual participation to alleviate the needs of those affected by Hurricane Katrina in New Orleans. Thousands of people were left unprotected and homeless, and the objective was to raise funds for the reconstruction of the devastated homes. Given the strong visual and metaphorical potential of installing a village of pink "houses" in the devastated area, Pink was the virtual city of hope, a hybrid of art, architecture, film, media and fundraising strategies.
Paper Log House. Shigeru Ban, 1955
For the victims of the Kobe earthquake. These emergency housing units have been built on two more occasions, in Turkey in 2000 and India in 2001. Self-built with maximum economy of means, they use sand-filled soft drink boxes as foundations, and walls constructed of cardboard tubes with insulating capacity and rain-resistant once protected with a kerosene primer. The tarpaulin roof, attached to a cardboard truss, can be removed and detached in summer to allow ventilation. The material cost of a 52 m2 unit is less than $2,000, and the assembly is designed to be carried out by the victims and volunteers themselves. Emergency housing took between 6 and 10 hours to build.
See also
Ephemeral art
Spanish Baroque ephemeral architecture
Spanish Baroque painting
Tactical urbanism
References
Architecture
Ephemera
Self-sustainability
Avant-garde art | Ephemeral architecture | [
"Engineering"
] | 5,394 | [
"Construction",
"Architecture"
] |
71,797,666 | https://en.wikipedia.org/wiki/Robert%20H.%20Carter%20III | Robert H. Carter III (January 12, 1847 - January 13, 1908) was an American pharmacist. He was the first African American certified pharmacist from Massachusetts.
By 1871, Carter worked for druggist and chemist William P. S. Caldwell on 49 Purchase Street. He married hairdresser Parthenia M. Harris on July 8, 1869. They had six children. Between 1876 and 1907, he owned and managed pharmacies in Boston and New Bedford, Massachusetts. On January 5, 1896, he was certified as a registered pharmacist. He worked as a pharmacist for 37 years. He was a member of the National Negro Business League.
He died January 13, 1908, in Brighton, Boston of tuberculosis.
References
1847 births
1908 deaths
Pharmacists from Massachusetts
African-American pharmacists
19th-century American pharmacists
19th-century American businesspeople
African-American businesspeople
Businesspeople from Boston
Tuberculosis deaths in Massachusetts | Robert H. Carter III | [
"Chemistry"
] | 205 | [
"Pharmacology",
"Pharmacology stubs",
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71,799,261 | https://en.wikipedia.org/wiki/Smart%20Upper%20Stage%20for%20Innovative%20Exploration | The Smart Upper Stage for Innovative Exploration (SUSIE) is a proposal for a reusable spacecraft designed by ArianeGroup. It is capable of manned operations, carrying up to five astronauts to low Earth orbit (LEO), or alternatively functioning as an automated freighter capable of delivering payloads of up to seven tons. It is envisioned to be launched on the Ariane 64 launch vehicle for European Space Agency (ESA) missions.
History
Work on what would become SUSIE commenced during 2020; in addition to ArianeGroup, various other European aerospace companies, including Airbus, Thales Alenia Space, and D-Orbit, have been early contributors to the project. The existence of SUSIE was revealed during the 2022 International Astronautical Congress in Paris. From an early stage, its development has been actively supported via research funding provided by the ESA's "New European Space Transportation Solutions" (NESTS) initiative; It has also benefitted from other programmes, such as the Intermediate eXperimental Vehicle. Work on SUSIE had been reportedly enacted in response to the recognition of a strategic priority to ensure the ESA possesses autonomous logistics capabilities.
SUSIE is designed to be a fully-reusable spacecraft, both the takeoff and landing phases are to be performed vertically. It has an internal cargo bay volume of 40 cubic meters, which is capable of accommodating up to five astronauts or, in an automated cargo configuration, carry a maximum payload of seven tons. The design of SUSIE is intended to be scalable without necessitated significant aerodynamic changes; this scalability permits it to better perform various mission roles. The payload bay is to be adaptable, such as being convertible into additional habitable volume for the crew to occupy during a longer mission, or to be replaced with propellant tanks and engines that could function comparably to complete upper stage. On longer duration crewed missions, such as beyond Earth orbit, the payload bay can convert into extra habitable volume for the crew to live comfortably. With the addition of a suitable additional space transfer module, SUSIE could reportedly conduct lunar missions. It has also been envisioned that it could participate in the construction of large orbital infrastructure and deorbit end-of-life satellites and other orbital debris.
The takeoff of SUSIE requires an external launch vehicle, which is initially intended to be the Ariane 64 launch vehicle. Later on, SUSIE could be used in conjunction with a future ArianeGroup reusable heavy-lift launcher. When paired with the Ariane 64, the latter's payload fairing is substituted for SUSIE. When fully fuelled, the total mass of the spacecraft is predicted to be 25 tons, which corresponds to the low Earth orbit (LEO) performance of the Ariane 64.
During atmospheric re-entry, SUSIE is intended to perform a propulsive landing (instead of using parachutes); one advantage of this approach is that the mission abort safety system would remain effective at all stages of a crewed mission, not only during the launch phase. Throughout the descent, no greater than three Gs is to be encountered at any point. Instead of using an escape tower, the envisaged emergency crew escape system uses a series of rocket motors at key locations across the exterior of the craft. Several comparisons have been made to other contemporary reusable spaceship programmes, including the SpaceX Starship, SpaceX Dragon 2, and Boeing Starliner, in particular due to the 'bellyflop' style maneuver that SUSIE is envisioned to perform during re-entry.
On 25 October 2023, a 1/6th-scale demonstrator, weighing 100 kg and with a height of 2m, was test-fired by ArianeGroup for the first time at their facility in Les Mureaux outside Paris. By this point, ArianeGroup had also reportedly started work on an intermediate version of SUSIE, which would be smaller than the heavy version. So-called 'hop' testing of the demonstrator is scheduled to continue through to mid-2025; early tests are to be focused on guidance and navigation functionality, while later testing shall include rocket-powered controlled descent, drop, and abort sequences.
, the proposed development timeline set out that a smaller commercial cargo version of SUSIE could be potentially ready for 2028, while crewed missions using the full-scale craft would not be expected to occur before the early 2030s. The project has yet to secure both approval and funding from European officials.
References
External links
Announcement at press.ariane.group
Arianespace
Proposed crewed spacecraft | Smart Upper Stage for Innovative Exploration | [
"Astronomy"
] | 910 | [
"Rocketry stubs",
"Astronomy stubs"
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71,800,629 | https://en.wikipedia.org/wiki/Nondestructive%20Evaluation%204.0 | Nondestructive Evaluation 4.0 (NDE 4.0) has been defined by Vrana et al. as "the concept of cyber-physical non-destructive evaluation (including nondestructive testing) arising from Industry 4.0 digital technologies, physical inspection methods, and business models. It seeks to enhance inspection performance, integrity engineering and decision making for safety, sustainability, and quality assurance, as well as provide timely and relevant data to improve design, production, and maintenance characteristics."
NDE 4.0 arose in response to the emergence of the Fourth Industrial Revolution, which can be traced to the development of a high-tech strategy for the German government in 2015, under the term Industrie 4.0. The term became widely known in 2016 following its adoption as the theme of the World Economic Forum annual meeting in Davos.
The concept gained strength following the opening of the Center for the Fourth Industrial Revolution in 2016 in San Francisco. NDE 4.0 evolved in conjunction with Industry 4.0. It is recognized as a future goal by several global NDE organizations: the International Committee for Nondestructive Testing (ICNDT) has a Specialist international Group (SIG) on NDE 4.0, and the European Federation for Nondestructive Testing (EFNDT) created a working group designated as "EFNDT Working Group 10: NDE 4.0" (WG10). The importance of NDE 4.0 is reflected in the activities of NDE organizations throughout the world, including the American Society of Nondestructive Testing (ASNT), the British Institute of Non-Destructive Testing (BINDT), and the German Society for Non-Destructive Testing (DGZfP), through publications and training.
History
Leading to NDE 4.0, just as those leading to Industry 4.0 were prior developments that are divided into prior revolutions based on distinct technological and historical markers. These are usually defined for industry and hence for nondestructive evaluation.
NDE 1.0
The first revolution in nondestructive evaluation coincides with the first industrial revolution and refers to the period between approximately 1770 (following the invention of the Watt’s steam engine in 1769) and 1870. The transition from hand and artisanal production and “muscle power” to mechanized production and steam- and hydro-power necessitated the introduction of nondestructive testing. Prior to this period, people have tested objects for thousands of years through simple methods based human sensory perception – feeling, smelling listening and observing as appropriate.
The development in the first industrial revolution gave birth to non-destructive inspection through the introduction of tools that sharpened the human senses, and through tentative attempts at standardized procedures. Simple tools such as lenses, stethoscopes, tap and listen procedures and others, improved detection capabilities by enhancing human senses. Establishing procedures, made the outcome of the inspection comparable over time. At the same time, industrialization also made it necessary to expand quality assurance measures, a process that continues to this day.
NDE 2.0
The second revolution in NDE is commonly referred to as the period between 1870, with the appearance of first means of mass production, marked by the introduction of the conveyor belt, and 1969. As with the second revolution in industry, it is characterized by use of physical, chemical, mechanical and electrical knowledge to improve testing and evaluation.
The transformation of electromagnetic and acoustic waves, which lie outside the range of human perception, into signals that can be interpreted by humans, resulted in means of interrogating components for better visualization of material inhomogeneities at or close to the surface. Following the discovery of X-rays in 1895, it became a dominant method for testing, followed by gamma-ray testing and later, electromagnetic means of testing.
With the introduction of the transistor into electronics, testing methods such as ultrasound developed further into lighter, portable systems suitable for field testing. The first detectors for infrared and terahertz detection were invented around the same time and the first eddy current devices became available. Although these are critical methods of testing that persist to this day, further breakthroughs had to wait until digitization and digital electronics developed in the third NDE revolution.
NDE 3.0
The third revolution in NDE parallels the advent of microelectronics, digital technologies and computers. It is usually thought of as the period starting in 1969, marked by the introduction of the first programmable logic controller (PLC), and 2016. Digital inspection equipment, such as X-ray detectors, digital ultrasonic and eddy current equipment, and digital cameras became integral parts of the system of testing and evaluation. Robotics lead to automated processes, improving convenience, safety, speed and repeatability.
Digital technologies offered leaps in managing inspection data acquisition, storage, processing, 2D and 3D imaging, interpretation, and communication. Data processing and sharing became the norm. At the same time, these developments created new challenges and opportunities such as data security and integrity and introduced new concepts such as value of data and its monetization.
NDE 4.0
Whereas prior revolutions focused on improving testing and evaluation by taking advantage of the tools, methods and development available at the respective periods, the 4th NDE revolution is characterized by integration; integration of tools, testing methods, digital technologies, and communication into coherent closed-loop systems that allows both feedback and feed-forward to manufacturing. The purpose is improvement in testing and evaluation taking advantage of current and emerging production technologies and communication and information systems.
At the heart of NDE 4.0 are digitalization, networking, information transparency, communication and processing tools such as artificial intelligence and machine learning. One of the primary added values in NDE 4.0 is the possibility of product design and concurrent nondestructive evaluation through use of digital twins and digital threads, so that both design and testing can influence each other continuously. Another is the ability to serve emerging trends such as testing in custom manufacturing, remote testing and predictive maintenance over the lifetime of products.
NDE 4.0 is not a fixed set of rules and concepts but rather and evolving progression of ideas, tools and procedures brought about by advances in production, communication and processing. Its global purpose is to serve the needs of industry and respond to changes brought about by emergence of new opportunities.
Drivers and components
The primary driver of NDE 4.0 is the same as that of the fourth industrial revolution – the integration of digital tools and physical methods, driven by current digital technologies through introduction of new ways of digitalization of specific steps in NDE processes, with a promise of overall efficiency and reliability. There are three recognizable components of NDE 4.0. First, Industry 4.0 emerging digital technologies can be used to enhance NDE capabilities in what has been termed “Industry 4.0 for NDE”. Second, statistical analysis of NDE data provides insight into product performance and reliability. This is a valuable data source for Industry 4.0 to continuously improve the product design in the “NDE for Industry 4.0” process. Third, immersive training experiences, remote operation, intelligence augmentation, and data automation can enhance the NDE value proposition in terms of inspector safety and human performance in the third component of NDE 4.0 – the “Human Consideration”.
International Conference on NDE 4.0
The International Conference on NDE 4.0 was initiated by the ICNDT Specialist international Group (SIG) on NDE 4.0 and is planned to be organized bi-annually (this plan is currently altered due to the Corona Crises):
14/15 & 20/21 April 2021: Virtual Conference with 4 keynotes, 26 invited presentations and four panel discussions organized (video recordings available online) by DGZfP and co-sponsored by ICNDT
24 – 27 October 2022 in Berlin, Germany with 4 keynotes and 15 technical sessions (including Artificial intelligence, Digital twin, Additive Manufacturing, Extended Reality, Reliability, and Predictive Maintenance). This conference was organized by DGZfP and co-sponsored by ICNDT. At this conference the Kurzweil Award for High Impact in NDE 4.0 (named after Ray Kurzweil) was initiated and awarded to Prof. Dr. Norbert Meyendorf and Prof. Dr. Bernd Valeske for their work "Starting the Field of NDE 4.0".
3–6 March 2025 in Taj Yeshwantpur, India. This conference is organized by the Indian Society for Non-destructive Testing (ISNT) and co-sponsored by ICNDT.
Further reading
Peer-reviewed publications on the topic of NDE 4.0 were covered in multiple special issues and books:
2020: NDE 4.0 (Special Issue of Materials Evaluation)
2020: NDE 4.0 (Special Issue of Research in Nondestructive Evaluation)
2020/2021: Trends in NDE 4.0: Purpose, Technology, and Application (Topical Collection in Journal of Nondestructive Evaluation)
2021/2022: NDE 4.0: Technical Basics, Applications and Role of Societies (Topical Collection in Journal of Nondestructive Evaluation)
2022: Handbook of Nondestructive Evaluation 4.0 (Major Reference Work)
2022/2023: NDE 4.0 Creating success stories, building the eco-system and continuing research (Topical Collection in Journal of Nondestructive Evaluation)
References
Sources
https://www.gartner.com/en/information-technology/glossary/data-monetization
Industrial automation
Industrial computing
Internet of things
Technology forecasting
Big data
Fourth Industrial Revolution
Knowledge economy
Digital technology
Maintenance
Quality control | Nondestructive Evaluation 4.0 | [
"Materials_science",
"Technology",
"Engineering"
] | 1,974 | [
"Information and communications technology",
"Industrial automation",
"Industrial engineering",
"Automation",
"Nondestructive testing",
"Materials testing",
"Digital technology",
"Data",
"Big data",
"Mechanical engineering",
"Maintenance",
"Industrial computing"
] |
71,801,051 | https://en.wikipedia.org/wiki/Operation%20Menai%20Bridge | Operation Menai Bridge is the code name for plans related to the death of King Charles III, The name refers to a suspension bridge in Wales. The plan includes the announcement of his death, the period of official mourning, and the details of his state funeral. Planning for the King's funeral began almost immediately after Charles's accession to the throne upon the death of his mother and predecessor, Queen Elizabeth II.
Background
The death of King George VI was communicated by using the phrase "Hyde Park Corner", to avoid Buckingham Palace switchboard operators learning the news too soon. For Queen Elizabeth The Queen Mother, Operation Tay Bridge was put into motion upon her death. Other code names used were Operation Forth Bridge for Prince Philip, Duke of Edinburgh, and Operation London Bridge for Queen Elizabeth II. Since the latter died at Balmoral Castle in Scotland, Operation Unicorn was also put into effect upon her death.
Post-accession
Following the accession of Charles III, planning for his funeral began "in earnest" on 20 September 2022, the day following the Queen's state funeral. As of 2024, details for Operation Menai Bridge continued to be regularly updated and reviewed, in light of Charles's diagnosis with cancer that year.
A 2024 biography of Charles III by Robert Hardman claimed the King's funeral arrangements have "been upgraded" to Operation London Bridge, mirroring those of his mother's. Planning for Charles III's funeral arrangement began shortly after his coronation held in 2023. The biography also claims that the codename Operation Menai Bridge is now being used for William, Prince of Wales, replacing the codename previously used, Operation Clare Bridge.
References
Charles III
Future events
Non-combat military operations involving the United Kingdom
State funerals in the United Kingdom | Operation Menai Bridge | [
"Physics"
] | 358 | [
"Spacetime",
"Physical quantities",
"Time",
"Future"
] |
71,801,257 | https://en.wikipedia.org/wiki/6%20Tauri | 6 Tauri, also designated t Tauri, is a chemically peculiar star in the northern constellation of Taurus. It has an apparent visual magnitude of 5.8, so, according to the Bortle scale, it is faintly visible from suburban skies at night. Measurements made with the Gaia spacecraft show an annual parallax shift of , which is equivalent to a distance of around 363 light years from the Sun.
A stellar classification of B9III matches that of a B-type giant star, but a more detailed analysis gives a type of kB8HeB9.5V(HgMn), indicating a main sequence mercury-manganese star. Mercury-manganese stars are chemically peculiar stars with a specific over-abundance of mercury and manganese absorption lines in their spectra.
6 Tauri has a mass 2.8 times that of the Sun and a radius 2.5 times the Sun's. With an effective temperature of , it shines with a bolometric luminosity of . Evolutionary models indicate that it is still on the main sequence with an age of 224 million years.
References
Taurus (constellation)
Tauri, f
Tauri, 006
1079
Durchmusterung objects
Mercury-manganese stars
021933
016511
B-type giants
B-type main-sequence stars | 6 Tauri | [
"Astronomy"
] | 276 | [
"Taurus (constellation)",
"Constellations"
] |
71,803,271 | https://en.wikipedia.org/wiki/Pascale%20Domingo | Pascale Domingo is a French combustion physicist and aerothermochemist who uses large eddy simulation to study flames and reactive flows in turbulent fuel-air mixtures. She is a director of research for the French National Centre for Scientific Research (CNRS), and is affiliated with the Complexe de Recherche Interprofessionnel en Aérothermochimie (CORIA), a joint research unit of CNRS, the University of Rouen Normandy, and the Institut national des sciences appliquées de Rouen.
Education and career
Domingo completed a Ph.D. in physics in 1991 at the University of Rouen Normandy, with the dissertation Modélisation numérique de plasmas en écoulement supervised by Dany Vandromme. She was a postdoctoral researcher in 1992 in the Aeronautics and Astronautics department of Stanford University.
Recognition
Domingo was elected to the 2019 class of Fellows of The Combustion Institute, "for excellent contributions to the numerical simulation of flames including hybrid combustion regimes predicting major and minor chemical species".
References
External links
Year of birth missing (living people)
Living people
French physical chemists
French women physicists
French women chemists
Women physical chemists
Research directors of the French National Centre for Scientific Research
Fellows of the Combustion Institute | Pascale Domingo | [
"Chemistry"
] | 250 | [
"Fellows of the Combustion Institute",
"Combustion",
"Women physical chemists",
"Physical chemists"
] |
71,803,638 | https://en.wikipedia.org/wiki/7%20Tauri | 7 Tauri is a multiple star in the northern constellation of Taurus. It has a combined apparent visual magnitude of 5.95, so, according to the Bortle scale, it is faintly visible from suburban skies at night. Measurements made with the Gaia spacecraft show an annual parallax shift of , which is equivalent to a distance of around 593 light years from the Sun.
7 Tauri is a binary star with two nearly equal components about apart, designated as A and B. The spectrum of each star matches a stellar classification of A7V. away is a 10th-magnitude star, component C, which is itself a spectroscopic binary. In the past, these stars had been treated as a single system, but they are now known to have different proper motions and somewhat different distances.
References
Taurus (constellation)
Tauri, 007
1086
Durchmusterung objects
022091
016664
A-type main-sequence stars | 7 Tauri | [
"Astronomy"
] | 197 | [
"Taurus (constellation)",
"Constellations"
] |
53,315,357 | https://en.wikipedia.org/wiki/LG%20G6 | The LG G6 is an Android smartphone developed by LG Electronics as part of the LG G series. It was announced during Mobile World Congress on February 26, 2017, as the successor to the 2016 LG G5.
The G6 is distinguished by its 5.7-inch display, which features a taller, 2:1 aspect ratio (marketed as 18:9), than the 16:9 aspect ratio of most smartphones. A variant, called the LG G6+ was announced on June 19, 2017 with 128 GB storage and a Hi-Fi Quad DAC.
Specifications
Hardware
The LG G6 utilizes a metal chassis with a glass backing, and is IP68-rated for water and dust-resistance. It is available in black, white, and silver-color finishes. The G6 features a 1440p FullVision IPS LCD, with a diagonal size of 5.7 inches. LG stated that it intended for the G6 to be a large-screened phone that would still be compact and feasible for one-handed use; the display uses a 2:1 aspect ratio (marketed as "18:9") that is taller than the 16:9 displays used by the majority of smartphones. The G6 was also designed with slim bezels, and is slightly smaller in size than the G5. To allow for reinforcement around the corners of the display, the display panel itself has rounded edges. The display also supports HDR10 and Dolby Vision high-dynamic-range video.
Unlike the LG G3, G4 and G5, the LG G6's battery is non-user-replaceable.
The G6 utilizes the Qualcomm Snapdragon 821 system-on-chip with 4 GB of RAM. It is offered in models with 32 GB and 64 GB of internal storage, expandable via SD card. The G6+, on the other hand, comes with 4 GB RAM and 128 GB internal storage standard. The G6 includes a 3300 mAh battery; unlike the G5, it is not user-accessible. U.S. models support wireless charging, and all models support Qualcomm Quick Charge 3.0. Models in selected Asian markets included quad Digital-to-analog converters (DAC) to enhance sound output. The G6 drops the modular accessory system of the G5, which had been panned by critics. Similarly to the G5, the G6 features dual rear-facing cameras, with standard and wide-angle sensors. Unlike the G5, where the primary rear-facing camera has a resolution of 16 megapixels but the wide-angle rear-facing camera has a resolution of only 8 megapixels, both cameras have a resolution of 13 megapixels.
Software
LG G6 ships with Android 7.0 "Nougat" and LG UX. Some of LG's in-house applications have enhanced landscape modes intended to complement the 2:1 display; the camera app features shooting modes designed for use with square, 1:1 aspect ratio photos, and can display a camera roll sidebar when taking traditional 4:3 photos. The screen size also complements Android Nougat's native split-screen mode for running multiple apps at once. LG announced that it would provide a promotional "G6 Game Collection" offer with US$200 worth of in-game content for six games on Google Play Store (Cookie Jam, Crossy Road, Genies & Gems, Spider-Man Unlimited, SimCity BuildIt and Temple Run 2), oriented towards those built for one-handed play and optimizations for the aspect ratio.
In May 2018, LG began to deploy an update to Android Oreo.
In September 2019, Android 9 ''Pie'' was released for the LG G6 although some variants of the phone are not receiving the update or the FOTA update system is not working properly for those phones.
Reception
CNET contrasted the G6 with the previous year's G5, as well as its main launch competitor, the Samsung Galaxy S8. The design of the G6 was complimented for being more elegant and expansive than the G5, albeit less elegant than the similar but curved design of the Galaxy S8. LG was panned for its shift back to a non-removable battery, but the battery itself was praised for having a larger capacity than that of the G5. It was acknowledged that while the G6 does not include the latest Qualcomm Snapdragon 835 system-on-chip (making the Galaxy S8 perform better on benchmarks than the G6), there was no discernible difference in performance in real-world usage between them. The cameras were also praised for producing "sharp and vibrant images", with quality on par with other recent flagship phones. In conclusion, CNET felt that the G6 could appeal to users that had lost their trust in Samsung following the recall of the Galaxy Note 7, arguing that "while it doesn't have anything novel or buzzworthy, it's LG's most marketable and widely-appealing phone yet."
See also
LG G series
Comparison of smartphones
References
Further information
Android Authority Review
Android Police — The LG G6 gets tortured by JerryRigEverything, emerges mostly unscathed
External links
Android (operating system) devices
LG Electronics smartphones
Mobile phones introduced in 2017
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording
Discontinued flagship smartphones | LG G6 | [
"Technology"
] | 1,142 | [
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
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