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63,811,183 | https://en.wikipedia.org/wiki/Resource%20smoothing | In project management, resource smoothing is defined by A Guide to the Project Management Body of Knowledge (PMBOK Guide) as a "resource optimization technique in which free and total float are used without affecting the critical path" of a project. Resource smoothing as a resource optimization technique has only been introduced in the Sixth Edition of the PMBOK Guide (since 2017) and did not exist in its previous revisions. It is posed as an alternative and a distinct resource optimization technique beside resource leveling.
The main difference between resource leveling and resource smoothing is that while resource leveling uses the available float, thus may affect a critical path, resource smoothing uses free and total float without affecting any of the critical paths. Thus, while resource leveling can be considered a constraint in order to adjust with certain resource supply limitation, for example, not to over-work some human resources, resource smoothing can be considered a useful method to solve the problem of a more flexible constraint if time of a deadline is a stronger constraint.
Just like resource leveling, a resource smoothing problem could be formulated as an optimization problem. The problem could be solved by different optimization algorithms such as exact algorithms or metaheuristics.
See also
Resource allocation
Resource leveling
References
Further reading
Schedule (project management) | Resource smoothing | [
"Physics"
] | 257 | [
"Spacetime",
"Physical quantities",
"Time",
"Schedule (project management)"
] |
65,337,112 | https://en.wikipedia.org/wiki/Na%20Ji | Na Ji is an American biophysicist and the Luis Alvarez Memorial Chair in Experimental Physics at UC Berkeley, where her work focuses on optical microscopy techniques for in vivo imaging and biophotonics. She has a joint appointment as faculty scientist at Lawrence Berkeley National Laboratory.
Early life and education
Na Ji earned her Bachelor of Science in chemical physics at the University of Science & Technology of China in Hefei, China in 2000 before pursuing a Ph.D. in chemistry at the University of California, Berkeley in 2005. She then joined the Janelia Research Campus of Howard Hughes Medical Institute as a postdoctoral fellow, before starting her own group there in 2011, focused on developing new optical microscopy techniques for brain research.
Research and career
Na Ji's research at Janelia Research Campus was dedicated to understanding the input-output relationships in neural circuits in the cerebral cortex, using novel microscopy techniques mixing structured light and adaptive optics. In 2017 she joined UC Berkeley as an associate professor in the Department of Physics and Molecular and Cellular Biology. As of January 2024, she is currently a Professor of Neurobiology, as well as the Luis Alvarez Memorial Chair in Experimental Physics at UC Berkeley. Her research has allowed researchers in her field to understand the brain more in depth than ever before.
Personal life
Na Ji is married to Nobel prize laureate, Eric Betzig. With Betzig, she has two children, Max and Mia.
References
External links
21st-century women physicists
Living people
University of California, Berkeley faculty
Biophysicists
Women in optics
Year of birth missing (living people)
Microscopists | Na Ji | [
"Chemistry"
] | 322 | [
"Microscopists",
"Microscopy"
] |
65,337,773 | https://en.wikipedia.org/wiki/Jason%20satellite%20series | The Jason is a series of oceanographic altimeter satellites, including:
TOPEX/Poseidon (1992–2006), a joint-venture between NASA and CNES, predecessor to the Jason satellites
Jason-1 (2001–2013)
OSTM/Jason-2 (2008–2019)
Jason-3 (2016-)
Jason-CS A (Jason Continuity of Service-A), formerly Sentinel-6A, now called Sentinel-6 Michael Freilich (2020-)
Jason-CS B (Jason Continuity of Service-B), Sentinel-6B, planned for launch in 2025 | Jason satellite series | [
"Astronomy"
] | 124 | [
"Astronomy stubs",
"Spacecraft stubs"
] |
65,338,286 | https://en.wikipedia.org/wiki/Rosetti%20Marino | Rosetti Marino SpA is the parent company of an industrial group, listed in the Milan stock exchange of AIM Italia Mercato alternativo del capitale and comprising 18 companies, 9 branch offices and 1,200 employees.
History
Established in Ravenna on 1925 by founder Marino Rosetti, the activity of the company began supporting the local port and industrial area with carpentry works and small tanks fabrication.
1960s
The first offshore natural gas field in Europe is discovered near the Ravenna coast in the Adriatic Sea. A pioneering phase of research and production of hydrocarbons in which Rosetti Marino participates fabricating structures (jackets, decks) for offshore Fixed Platform. The customers are Eni, Agip and Montedison (now Edison (company)).
Today
Rosetti Marino is an EPCI Contractor of offshore and onshore plants for Energy sector, Shipbuilding and Superyachts, as well as in the provision of specialized technical services for the Oil & Gas sector.
Rosetti Marino group include other Italian companies involved in its own supply chain and a widespread international presence.
The company owns two shipyards in the port of Ravenna, the Piomboni Yard (offshore constructions) and the San Vitale Yard (shipbuilding works) while a third shipyard named KCOI, built in 2008, is located on the Kazakhstan shore of the Caspian Sea near the city of Aktau.
The main clients are some of the major international companies and international contractors in the Oil & Gas Energy sector such as ENI, TOTAL, Shell, ConocoPhillips, QatarGas, Premier Oil as well as some of the main European ship owners.
References
Energy engineering and contractor companies
Engineering companies of Italy
Energy companies established in 1925
Oil and gas companies of Italy
Italian brands
Italian companies established in 1925 | Rosetti Marino | [
"Engineering"
] | 359 | [
"Energy engineering and contractor companies",
"Engineering companies"
] |
65,338,486 | https://en.wikipedia.org/wiki/Amnon%20Aharony | Amnon Aharony (Hebrew: אמנון אהרוני; born: 7 January 1943) is an Israeli Professor (Emeritus) of Physics in the School of Physics and Astronomy at Tel Aviv University, Israel and in the Physics Department of Ben Gurion University of the Negev, Israel. After years of research on statistical physics (critical phenomena, random systems, fractals, percolation), his current research focuses on condensed matter theory, especially in mesoscopic physics and spintronics.
He is a member of the Israel Academy of Sciences and Humanities, a Foreign Honorary Member of the American Academy of Arts and Sciences and of several other academies. He also received several prizes, including the Rothschild Prize in Physical Sciences, and the Gunnar Randers Research Prize, awarded every other year by the King of Norway.
Early life and education
Amnon Aharony was born in Jerusalem, and grew up in Netanya, Israel. He received his B.Sc. in Physics and Mathematics in 1964 from the Hebrew University of Jerusalem. His M.Sc. thesis, under the supervision of Gideon Rakavy, was on the distorted wave Born approximation for direct nuclear reactions (1965), from the same university. He received his doctorate in 1972 from Tel Aviv University, under the supervision of Yuval Ne'eman. Thesis title: Aspects of time reversal symmetry violation.
Career
Aharony was a senior researcher in the Israel Army and Ministry of Defense during 1965–1972. In those years he was also a teaching instructor in Tel Aviv University. Aharony was a postdoctoral student at Cornell University with Michael Fisher, and also at Harvard University, the University of California, San Diego and at Bell Laboratories in Murray Hill.
He returned to Israel in 1975 to become an associate professor of physics in Tel Aviv University, and a full professor in 1979. From 1990 he held the Moyses Nussenzveig Chair in Statistical Physics. Aharony retired from the university as Professor Emeritus in 2006. At that year he joined Ben Gurion University of the Negev, where he became Distinguished Professor Emeritus during 2013–2020.
During the years, Aharony was a visiting professor at Harvard University, MIT, Boston University, University of Tokyo, NTT Japan, the International Institute of Physics, UFRN, Natal, Brazil, the Institute for Advanced Studies in Jerusalem, the Institute of theoretical physics of the Chinese Academy of Sciences in Beijing. He was also a Distinguished Professor at the National Cheng Kung University, Taiwan and a visiting scientist at the IBM Research laboratories in Yorktown Heights and in Zürich, the US National Laboratories in Argonne and the National Institute of Standards and Technology (NIST), the Beijing Computational Science Research Center and the Institute for Basic Science in Daejeon, Korea.
Aharony was also an adjunct professor in the University of Oslo, Norway during the years 1987–2012, and a Consultant at IBM Research, MIT and the Weizmann Institute of Science (1987–present).
Research
Phase transitions: Aharony applied the renormalization group to identify and classify universality classes of critical (e.g. cubic, dipolar) and multicritical points.
His work on random systems involved systems with random fields
and the general issues of self-averaging. Aharony introduced fractal geometry into several branches of statistical physics, especially in connection with the many fractal sub-structures of dilute percolating systems, with applications to oil recovery.
Quantum magnetism: Aharony explained the structures and phase diagrams of magnetic oxide systems. This includes the magnetic structures of the high temperature superconducting parent cuprates, and the prediction of the spin glass phase there, the discovery of a special symmetry in the Dzyaloshinskii-Moria interaction (now called the Shekhtman-Entin-Wohlman-Aharony symmetry) and the ordered phases of various multiferroic materials.
Mesoscopic physics: Aharony participated in critical discussions of the Aharonov-Bohm interferometer.
In recent years, he concentrates on the effects of the spin-orbit interaction on transport in mesoscopic spintronic systems, including proposals of spin filters which may be relevant to quantum information processing.
Publications
Aharony is the author of 8 books and more than 450 articles. According to Google Scholar (September 2023) he has more than 50,000 citations and his h-index is 87.
Selected books
A. Aharony and J. Feder, editors. Fractals in Physics. Proceedings of a Conference, Vence, France (North Holland, Amsterdam, 1989)
D. Stauffer and A. Aharony. Introduction to Percolation Theory. Taylor and Francis, London (1992); revised 2nd edition (1994); German translation: Perkolationstheorie, Eine Einführung, VCH, Weinheim (1995); Japanese translation: PA-KO RE-SHON NO KI HON GEN RI, Yoshiokashoten, Kyoto (2001).
A. Aharony and O. Entin-Wohlman, editors. Perspectives of Mesoscopic Physics. World Scientific, Singapore (2010)
A. Aharony and O. Entin-Wohlman. Introduction to Solid State Physics. In Hebrew, Open University, Israel (2018), 600 pages; English translation: World Scientific, Singapore (2018)
Honors and awards
Fulbright Fellowship, US, 1972
Fellow, American Physical Society, USA, 1985, "for contributions to the theory of new critical and multicritical points, of random field systems and their experimental realization and of using fractals in statistical physics and in percolation"
Foreign Member, Norwegian Academy of Science and Letters, Oslo, Norway, 1988
Member, Royal Norwegian Society of Sciences and Letters, Trondheim, Norway, 1993
Foreign Honorary Member, American Academy of Arts and Sciences, Cambridge, MA, USA, 2002
Honorary fellow, Institute of Physics, UK, 2011
Elected member, Israel Academy of Sciences and Humanities, 2012
Notable students
Joan Adler
Serge Galam
Yigal Meir
Personal life
Aharony is the father of Professor of Physics Ofer Aharony, psychologist Dr. Tamar Aharony and Professor of music Iddo Aharony.
References
External links
Amnon Aharony, Ben Gurion University
Prof. Amnon Aharony, Tel Aviv University
A lecture by Amnon Aharony: Quantum theory: does God play dice? (in Hebrew), YouTube
Members of the Norwegian Academy of Science and Letters
Royal Norwegian Society of Sciences and Letters
Condensed matter physicists
Israeli physicists
Tel Aviv University alumni
Hebrew University of Jerusalem alumni
Academic staff of Ben-Gurion University of the Negev
Fellows of the American Physical Society
1943 births
Living people
Weizmann Prize recipients | Amnon Aharony | [
"Physics",
"Materials_science"
] | 1,399 | [
"Condensed matter physicists",
"Condensed matter physics"
] |
65,338,494 | https://en.wikipedia.org/wiki/Suliana%20Manley | Suliana Manley (born 1975) is an American biophysicist. Her research focuses on the development of high-resolution optical instruments, and their application in studying the organization and dynamics of proteins. She is a professor at École Polytechnique Fédérale de Lausanne and heads the Laboratory of Experimental Biophysics.
Career
Manley studied physics and mathematics at Rice University where she received a Bachelor's degree (cum laude) in 1997. She joined Harvard University and in 2004 graduated with a PhD in physics under the supervision of Dave A. Weitz. She then went to work as a postdoctoral researcher on lipid bilayer and red blood cell membrane dynamics with Alice P. Gast at MIT. In 2006, she joined the cell biology laboratory of Jennifer Lippincott-Schwartz at the National Institutes of Health as post-doctoral fellow. Here she developed an optical method (sptPALM) enabling the study of the dynamics of large ensembles of single proteins in membranes and inside cells.
In 2009, she became an assistant professor of physics at the École Polytechnique Fédérale de Lausanne, and was promoted to associate professor in 2016 and to full professor in 2022. She is the founding director of the Laboratory of Experimental Biophysics.
Recognition
In 2019, Manley was awarded the Medal for Innovation in Light Microscopy by Royal Microscopical Society. In 2020, she was elected as an APS (American Physical Society) fellow.
Research
Manley's research group is invested in the field of high-resolution optical instruments and in the investigation of complex biological systems. They develop and deploy automated super-resolution fluorescence imaging techniques combined with live cell imaging and single molecule tracking. Their aim is to determine both the dynamics and the spatial distribution of protein assembly. They are also interested in the information transduction across cell membranes and therefore investigate the assembly dynamics of membrane-bound receptor.
Their main research topics involve:
High-throughput and large field-of-view single molecule localization microscopies (SMLM) by application of microlens array (MLA)-based flat-field epi-illumination.
Multicolor 3D single particle reconstruction from multicolor 2D SMLM images.
Waveguide TIRF for high-throughput DNA-PAINT for better precision of target localization and continuous target sampling.
Study of the physical and physiological signatures of mitochondria division and fusion.
Publication
Patterson, George, Michael Davidson, Suliana Manley, and Jennifer Lippincott-Schwartz. "Superresolution imaging using single-molecule localization." Annual review of physical chemistry 61 (2010): 345-367. Doi:10.1146/annurev.physchem.012809.103444
References
External links
Laboratory of Experimental Biophysics
Academic staff of the École Polytechnique Fédérale de Lausanne
Rice University alumni
1975 births
Living people
American women scientists
Harvard University alumni
American biophysicists
Fellows of the American Physical Society
American women academics
21st-century American women
Microscopists | Suliana Manley | [
"Chemistry"
] | 612 | [
"Microscopists",
"Microscopy"
] |
65,340,929 | https://en.wikipedia.org/wiki/Urban%20evolution | Urban evolution refers to the heritable genetic changes of populations in response to urban development and anthropogenic activities in urban areas. Urban evolution can be caused by non-random mating, mutation, genetic drift, gene flow, or evolution by natural selection. In the context of Earth's living history, rapid urbanization is a relatively recent phenomenon, yet biologists have already observed evolutionary change in numerous species compared to their rural counterparts on a relatively short timescale.
Strong selection pressures due to urbanization play a big role in this process. Urbanization introduces distinct challenges such as altered microclimates, pollution, habitat fragmentation, and differential resource availability. These changed environmental conditions exert unique selection pressures on their inhabitants, leading to physiological and behavioral adaptations in city-dwelling plant and animal species. However, there is also discussion on whether some of these emerging traits are truly a consequence of genetic adaptation, or examples of phenotypic plasticity. There is also a significant change in species composition between rural and urban ecosystems.
Understanding how anthropogenic activity can influence the traits of other living beings can help humans better understand their effect on the environment, particularly as cities continue to grow. Shared aspects of cities worldwide give ample opportunity for scientists to study the specific evolutionary responses in these rapidly changed landscapes independently. How certain organisms adapt to urban environments while others cannot gives a live perspective on rapid evolution.
Urbanization
With urban growth, the urban-rural gradient has seen a large shift in distribution of humans, moving from low density to very high density within the last millennia. This has brought a large change to environments as well as societies.
Urbanization transforms natural habitats into completely altered living spaces that sustain large human populations. Increasing congregation of humans accompanies the expansion of infrastructure, industry and housing. Natural vegetation and soil are mostly replaced or covered by dense grey materials. Urbanized areas continue to expand both in size and number globally; in 2018, the United Nations estimated that 68% of people globally will live in ever-expanding urban areas by 2050.
Urban evolution selective agents
Urbanization intensifies diverse stressors spatiotemporally such that they can act in concert to cause rapid evolutionary consequences such as extinction, maladaptation, or adaptation. Three factors have come to the forefront as the main evolutionary influencers in urban areas: the urban microclimate, pollution, and urban habitat fragmentation. These influence the processes that drive evolution, such as natural and sexual selection, mutation, gene flow and genetic drift.
Urban microclimate
A microclimate is defined as any area where the climate differs from the surrounding area. Modifications of the landscape and other abiotic factors contribute to a changed climate in urban areas. The use of impervious dark surfaces which retain and reflect heat, and human generated heat energy lead to an urban heat island in the center of cities, where the temperature is increased significantly. A large urban microclimate does not only affect temperature, but also rainfall, snowfall, air pressure and wind, the concentration of polluted air, and how long that air remains in the city.
These climatological transformations increase selection pressure on species living in urban areas, driving evolutionary changes. Certain species have shown to be adapting to the urban microclimate.
For example, a research study focused on urban thermal heterogeneity, which can lead to the formation of Urban heat islands, shows how variations in temperature due to urbanization significantly affects Feral pigeons (Columba livia) causing changes in their metabolic processes and oxidative stress levels. Specifically, pigeons in hotter areas showed elevated oxidative stress, suggesting that urban heat could compromise their health.
Urban pollution
Many species have evolved over macroevolutionary timescales by adapting in response to the presence of toxins in the environment of the planet. Human activities, including urbanization, have greatly increased selection pressures due to pollution of the environment, climate change, ocean acidification, and other stressors. Species in urban settings must deal with higher concentrations of contaminants than naturally would occur.
There are two main forms of pollution which lead to selective pressures: energy or chemical substances. Energy pollution can come in the form of artificial lighting, sounds, thermal changes, radioactive contamination and electromagnetic waves. Chemical pollution leads to the contamination of the atmosphere, the soil, water and food. All these polluting factors pose direct and indirect challenges to species inhabiting urban areas, altering species’ behavior and/or physiology, which in turn can lead to evolutionary changes.
Air pollution and soil pollution have significant physiological impacts on both wildlife and plants. For urban animals, exposure to pollutants often results in respiratory issues, neurological damage, and skin irritations. Over time, animals may adapt to these stressors through changes in their physiological systems, such as increased lung capacity or more efficient detoxification mechanisms to cope with pollutants. However, the severity of these adaptations varies across species, with some developing resilience while others face diminished health. The peppered moth (Biston betularia) is a classic example of industrial melanism, where moth populations adapted to increased soot and pollutants by evolving darker coloration, which allowed them to better blend into the soot-darkened trees during the industrial revolution
For plants, long-term exposure to pollutants like ozone can impair vital structures on their leaves, disrupting gas exchange and reducing growth. Some plants adapt by closing their stomata or producing antioxidants to mitigate the damage, while others are less equipped to cope and show signs of decline. Pollution also alters soil chemistry, affecting nutrient availability and further stressing plant growth. These physiological changes to both flora and fauna influence urban ecosystems, determining which species can survive and reproduce in polluted environments.
A study on Great tits (Parus major) also found that air pollutants, in combination with local tree composition and temperature, affect their nestling physiology. Specifically, antioxidant capacity and fatty acid composition in these birds were influenced by the surrounding environmental conditions, including pollution levels.
Water pollution is another major concern, to which species living in aquatic habitats, such as fish, can evolve resistance to pollutants. The Atlantic killifish (Fundulus heteroclitus) has evolved to resist toxic pollutants like polychlorinated biphenyls (PCBs), commonly found in polluted urban waters. This resistance is thought to be the result of mutations that allow the fish to tolerate high levels of chemicals that would otherwise be lethal.
Noise pollution, often resulting from traffic, construction, and industrial activities, is another form of energy pollution that significantly affects urban species. Prolonged exposure to high noise levels can interfere with animals' communication, navigation, feeding behaviors, and stress response mechanisms. In particular, birds are sensitive to noise pollution, as it disrupts their ability to communicate using signals, such as calls from potential mates or warnings of predators. This disruption can lead to changes in behavior, reproduction, and survival.
Urban habitat fragmentation
The fragmentation of previously intact natural habitats into smaller pockets which can still sustain organisms leads to selection and adaptation of species. These new urban patches, often called urban green spaces, come in all shapes and sizes ranging from parks, gardens, plants on balconies, to the breaks in pavement and ledges on buildings. The diversity in habitats leads to adaptation of local organisms to their own niche. And contrary to popular belief, there is higher biodiversity in urban areas than previously believed. This is due to the numerous microhabitats. These remnants of wild vegetation or artificially created habitats with often exotic plants and animals all support different kinds of species, which leads to pockets of diversity inside cities.
With habitat fragmentation also comes genetic fragmentation; genetic drift and inbreeding within small isolated populations results in low genetic variation in the gene pool. Low genetic variation is generally seen as bad for chances of survival. This is why probably some species aren’t able to sustain themselves in the fragmented environments of urban areas.
Urban environments create new selection pressures for species, leading to rapid adaptations. Species may experience changes in behavior, morphology, or physiology due to altered resources, human-induced pollution, and fragmented habitats. For instance, city-dwelling animals like birds may evolve shorter wings to better navigate between buildings, or insects might develop resistance to pesticides commonly used in urban settings. Urban heat islands are another factor contributing to urban evolution. Cities tend to be warmer than surrounding rural areas, causing species to adapt to higher temperatures. some insects have been observed to become more heat-tolerant over time. Pollution and light exposure also play a significant role. Many species must adapt to high levels of pollution in cities or artificial light that disrupts their natural behaviors. example birds in cities often start singing earlier in the morning due to the prevalence of artificial lighting, which can affect their mating patterns. Fragmentation of habitats has led to the creation of micro-habitats within cities, which act as isolated evolutionary zones. Species in these fragmented areas often experience unique evolutionary pressures, leading to genetic drift and divergence from rural populations.
In one study, researchers examined how early life experiences, particularly adverse conditions, influence behavior in European starlings (Sturnus vulgaris). The study specifically explored how early life adversity—such as nutritional stress or challenging environmental conditions—may trigger adaptive behaviors in the starlings, including increased foraging and actively seeking out information later in life. The birds were found to be more efficient at locating food and gathering relevant information from their surroundings, suggesting that early adversity may encourage greater exploration and resource acquisition strategies as an adaptive response to uncertainty.
Their findings imply that animals experiencing early adversity in fragmented environments may develop enhanced abilities to locate and exploit scattered resources. This may help explain why some species, such as starlings, are able to persist and even thrive in urban settings despite habitat degradation. Fragmented urban habitats tend to be more unpredictable, with food sources often patchy and habitats divided. In such environments, animals that have faced early adversity may become more adept at navigating these challenges. Just as the starlings in the study displayed increased cognitive flexibility in their foraging and information-gathering behaviors, animals in urban ecosystems may also adopt similar strategies to cope with the effects of habitat fragmentation. Cognitive flexibility enables animals to adapt to fluctuating conditions, such as changes in food availability or alterations to shelter and nesting sites, which are common in urbanized landscapes.
Resource Availability
Urbanization often leads to changes in the availability and distribution of food, water, and shelter, prompting behavioral, physiological, and morphological adaptations in species that can exploit new resource environments. Resource availability also acts as a selective force in urban evolution, influencing the survival and reproductive success of species living in cities. Urban areas offer a distinctive array of resources, including food sources like garbage, human waste, and crops, often differing in quantity and quality from those found in natural habitats. These variations can create evolutionary pressures on local populations. This can be seen in the New York City white-footed mice (Peromyscus leucopus) as its tooth rows adapt a structure that can chew on the foods and resources available.
Urban Raccoons (Procyon lotor) have also adapted to urban environments by exploiting food sources like garbage, pet food, and bird feeders. These animals have developed more adaptable foraging behaviors and are known to thrive in cities due to the abundance of easily accessible food. A recent study reveals the urban raccoons ability to solve foraging challenges, demonstrating innovative problem-solving skills. The research showed that raccoons use puzzle boxes with different difficulty levels to obtain food, with some raccoons learning to solve increasingly complex tasks. The study found that younger raccoons, who were more willing to take risks, were more successful at solving the puzzles. This study shows how raccoons adapt to urban environments through learning and behavioral flexibility, and suggests that finding ways to find resources drive these cognitive adaptations.
Examples of Urban Evolution
Adaptation and Natural Selection
The urban environment imposes different selection pressures than the typical natural setting. These stressors elicit phenotypic changes in populations of organisms which may be due to phenotypic plasticity—the ability of individual organisms to express different phenotypes from the same genotype as a result of exposure to different environmental conditions—or actual genetic changes.
Mutations are genotypic changes that may result in changes in phenotype, altering the observable traits of an organism and thus potentially its interactions or relationship with its environment. Mutations produce genetic variation which can be acted upon by evolutionary processes such as natural selection. For evolution to occur through natural selection, there must be genetic variation within a population, differential survival as a consequence of the genetic variation, and selective pressure from the environment towards particular desirable or undesirable traits.
Thus, in considering the examples of urban evolution, observed phenotypic divergences or differences in response to urbanization have to be genetically based and increase fitness in that particular environment to be tagged as evolution and adaptation, respectively. Hence, it will be appropriate to consider neutral, or non-adaptive, and adaptive urban evolution, with the later needing to be sufficiently proven.
Although there is widespread agreement that adaptation is occurring in urban populations, there are few completely proven examples of evolution – almost all are cases of selection, reasoned speculation connecting to adaptive benefit, but insufficient evidence of genetically based, actual adaptive phenotype. At this time the following examples are sufficiently demonstrated:
Multiple Atlantic killifish (Fundulus heteroclitus) populations have independently evolved pollution-resistant characteristics such as whole-body chemical tolerance and aryl hydrocarbon receptors. Bioaccumulating polychlorinated biphenyl (PCB) chemicals are often disposed of into the water of urban estuary habitats and cause developmental defects in many vertebrates. The killifish evolved resistance to model pollutant PCB-126. Quantitative trait locus mapping indicated that genes responsible for aryl hydrocarbon receptor signaling may potentially be responsible for this chemical resistance, with resistant F.heteroclitus populations exhibiting a desensitized signaling pathway. This genetic change was also determined to be heritable. Killifish were consequently found to be 8,000 times more resistant to environmental pollutants than other species of fish.
The peppered moth is an example of industrial melanism. These moths changed color from light to dark due to anthropogenic air pollution during the industrial revolution. With soot release as a consequence of coal burning, the urban trees that the moths would reside on became darker. Additionally, the lichens died as well, leaving little cover for the moths to camouflage. The black melanism phenotype frequency saw a rise during the time of heavy air pollution and a fall after cleaner air became more normal again in cities.
Acorn ants (Temnothorax curvispinosus) adapt to tolerate increased urban temperatures. As a consequence of abundant heat-retaining manmade materials such as concrete and steel in urban environments, cities tend to exhibit a heat island effect. Compared to rural populations, urban populations of T.curvispinosus were more tolerating of a rapid rate of temperature increase, and higher temperatures overall.
The water flea (Daphnia magna) has adapted to urban settings and displays the ability to better tolerate heat. Likely as a consequence of the urban heat island and thus warmer pond water, water fleas have also evolved even more towards a "fast living" pace of life - they mature faster, reproduce quicker, produce more offspring, are smaller, and have a higher maximum population growth rate than rural populations of the same species.
Ragweed (Ambrosia artemisiifolia) has very divergent flowering phenology. Urban A.artemisiifolia also exhibit a greater variance in terms of plant height than rural members of the species.
Holy hawksbeard (Crepis sancta) develops larger size, later flowering, delayed senescence, higher photosynthetic capacity, higher water use efficiency, and higher leaf nitrogen in urban areas.
Other claimed examples of adaptation indicative of potential urban evolution include:
Genome sequencing of New York City brown rats (Rattus norvegicus) has revealed significant selective sweeps at loci for metabolic, nervous, locomotive, and diet-related genes. These sweeps were also unique to the New York City population. This indicates not only that populations are undergoing unique genetic changes in urban environments, but also that these mutations are beneficial in their environment, and increasing in frequency. This consequently demonstrates the processes of adaptation and urban evolution.
Humans often attempt to curb rodent populations through the use of rodenticides. Anticoagulant-class rodenticides alter the rate of blood coagulation through its effects on the vitamin K reductase (VKOR) enzyme. Sequencing of the associated VKOR gene, VKORC1, in rat and mice species indicated mutations in said gene. There was also observed resistance to the rodenticides in these mice. Presence of mutation and consequential resistance to these rodenticides indicate genetic change and resulting adaptation to the anthropogenic chemical.
The guppy (Poecilia reticulata) in urban environments exhibited reduced color expression and lower sperm load. In these fish, expression of bright colors is typically used to attract mates and is therefore typically vulnerable to sexual selection. Such “attractive” traits and traits that otherwise maximize fertilization potential are favored by sexual selection. However, both of these sexually favorable traits were less expressed in urban populations. This was hypothesized to be a consequence of urban pollution. Pollution alters the underwater visibility of the bright colors, making them costly to exhibit without the benefit of being noticeable to a mate. The polluted urban waters are harsher and therefore individuals may need to prioritize investment in traits for survival rather than reproduction, potentially resulting in lower sperm load. Sexual selection was weaker in urban streams than in rural streams.
New York City white-footed mice (Peromyscus leucopus) had shorter upper and lower tooth rows relative to their rural counterparts. Longer tooth rows are advantageous for eating low-quality foods, which typically require more chewing. Urban mice having shorter tooth rows consequently implies that they consume softer food or food of higher quality due to differential availability of nutritional food in urban and rural environments.
House finches (Carpodacus mexicanus) in urban environments showed divergence from their rural counterparts in terms of bill morphology and bite force. House finches in urban areas rely on different food sources than those in rural desert areas - urban house finches eat more sunflower seeds from bird feeders, which are larger and harder than the non-anthropogenic seeds found naturally occurring in the native desert habitat that rural finches continue to reside in. Thus, urban house finches have evolved longer and wider beaks compared to the shorter beaks of desert house finches. It was discovered that the urban finches express bone morphogenetic proteins at larger doses and earlier on in their development, a likely biochemical cause to their larger beaks.
The common blackbird (Turdus merula) may be the first example of actual speciation by urban evolution, due to the urban heat island and food abundance the urban blackbird has become non-migratory in urban areas. The birds also sing higher and at different times, and they breed earlier than their rural counterparts which leads to sexual selection and a separated gene pool. Natural behavioral differences have also formed between urban and rural birds.
Urban Anole lizards (Anolis) have evolved longer limbs and more lamellae compared with anolis lizards from forest habitats. This because the lizards can navigate the artificial building materials used in cities better.
The urban Hawksbeard plant (Crepis) has evolved a higher percentage of heavier nondispersing seeds compared to rural hawksbeard plants, because habitat fragmentation leads to a lower chance of dispersing seeds to settle.
White clover (Trifolium repens) has repeatedly adapted to urban environments on a global scale due to genetic changes in a heritable antiherbivore defense trait (hydryogen cyanide) in response to urban-rural changes in drought stress, vegetation and winter temperatures.
The London Underground mosquito (Culex pipiens f. molestus) has undergone reproductive isolation in populations at higher latitudes, including the London Underground railway populations, where attempted hybridizations between molestus and the surface-living Culex pipiens pipiens are not viable in contrast to populations of pipiens and molestus in cities at lower latitudes where hybrids are found naturally.
Urban Peromyscus leucopus, microtus pennylvanicus, Eptesicus fuscus, and Sorex cinereus all showed a statistically significant larger cranial capacity relative to rural members of the same respective species. An increased cranial size may be associated with development of novel behaviors to cope with the new stresses of the urban environment. However, it is not entirely certain whether this is an example of true evolution or behavioral plasticity - no sustained cranial capacity increase over time was observed. In fact, the cranial size decreased over time in urban populations.
It is important to note that while these examples show genetic change and/or adaptation, they are not completely proven to be examples of evolution, whether due to insufficient evidence of heritability, or being a possible result of something else, such as plasticity, or because of insufficient evidence.
Some interesting cases of possible adaptation which remain insufficiently proven are:
Bobcats (Lynx rufus) in Los Angeles, CA, USA were selected for immune genetics loci by an epidemic of mange there, however Serieys et al. 2014 does not provide proof of resistant phenotype.
Water dragon lizards (Intellagama lesueurii) in Brisbane, Australia do show divergence. Littleford-Colquhoun et al. 2017 find divergence of both morphology and genetics, but remind readers that they have not demonstrated that this is adaptive.
In one case selection is widely expected to occur and yet is not found:
Coyotes (Canis latrans) in New York City, USA show no immune selection in the work of DeCandia et al. 2019.
Genetic Drift and Gene Flow
Evolution is not strictly the result of natural selection and beneficial adaptation. Evolution may also result from genetic drift due to population bottlenecks. In a population bottleneck, the population size is reduced randomly and significantly; there is no selection and therefore random alleles may be kept whereas others decreased in the population. The bottlenecked population may thus show different allele frequencies and phenotypic frequencies than the original population.
A population bottleneck may arise from anthropogenic factors common in urban areas, such as habitat fragmentation from abundant infrastructure. Habitat fragmentation may also lead to reduction in gene flow, further isolating populations of the same species from one another. Cities have been found to both increase genetic drift and decrease gene flow. In an overview of 167 different studies, over 90% indicated a correlation between genetic drift, gene flow, and urbanization. This genetic isolation of urban populations can result in divergence from the original and rural populations of the same species, leading to nonadaptive evolution.
An example of nonadaptive change related to genetic drift and gene flow is the burrowing owl (Athene cunicularia) in urban Argentina. Each of the three studied cities was independently colonized by a unique population of owls, and there was minimal gene flow between urban owls and those of nearby rural populations. Moreover, there was no gene flow between the owl populations of the three different cities. Gene sequencing revealed that there was less variation present in single nucleotide polymorphisms (SNPS) in urban populations relative to rural populations, and the different cities had different rare SNPS. The different urban populations were genetically isolated from each other and exhibited genetic divergence when compared to both other urban populations and rural populations. This was also seen in New York City white-footed mice. Urbanization limited their habitat to predominantly city parks, and the independent city park populations were genetically discrete.
Phenotypic Plasticity
When species show apparent adaptation to an urban or other environment, that adaptation is not necessarily a consequence of evolution, or even genetic change. One genotype may be able to produce various phenotypes adaptive to different environmental conditions. In other words, divergent observable traits may arise from one set of genes and therefore, genetic change did not occur to produce these traits, and evolution did not occur. However, genetic evolution, phenotypic plasticity, and even other factors such as learning may all contribute in varying degrees to form the apparent phenotypic difference.
For example, when 3,768 bird species were assessed in multiple urban environments, it was determined that urban species are generally smaller in size, occupy less specific niches, live longer, have more eggs, and are less aggressive in defending territory. While there are statistically significant differences between the urban and rural birds of various species, this cannot be assumed to be purely genetic, especially since this study did not explore the potential genetic background of the phenotypic variations.
Another study examines how urbanization influences plant responses to herbivory, using the common dandelion (Taraxacum officinale) along an urbanization gradient. Plants from different urban, suburban, and rural areas were raised under similar conditions and exposed to herbivory (locust grazing). While all plants increased their resistance to herbivores with repeated exposure, urban plants showed reduced early seed production compared to rural and suburban plants. This study suggests that urbanization affects plant defenses and fitness, with urban populations showing different reaction norms in response to herbivory.
A more specific example of phenotypic plasticity is behavioral plasticity, which is often observed in urban areas. In the dark-eyed junco (Junco hyemalis), it was determined that phenotypic plasticity was in part responsible for the differential nesting behaviors of urban dwellers. In order to adapt to the noise pollution abundantly present in urbanized areas, city-dwelling dark-eyed junco birds utilized higher frequency songs to communicate with one another relative to rural birds. It was determined that even in experimental conditions the birds from urbanized areas continued to sing at louder frequencies even without noise present. While this could have been indicative of a genetic basis and thus evolution, it was also observed that prior to capture, birds would exhibit sharing of song with one another. The higher frequency song in the captured experimental population could have therefore been a result of learning from other birds. However, the birds also show significant genetic variation in multiple traits related to reproductive and endocrine systems. This example shows demonstrates the complex interrelation between genetic change, phenotypic and behavioral plasticity, adaptation, and learning in the formation of a novel or changed phenotype.
Species Composition
As a region urbanizes the species composition generally undergoes change. The new conditions associated with urban infrastructure, air and noise pollution, habitat fragmentation, differential food availability, humans and cars, and so on may be difficult for certain species to adapt to. In birds, for instance, rare species generally disappear in urban areas, with species that are more adaptable tend to dominate. This results in homogenization. In plants, urbanization reduces species richness and introduces homogeny. It also decreases the amount of pollinators, which may increase reproductive difficulty.
References
Ecology terminology
Community ecology
Habitat
Ecological processes
Evolutionary ecology
City | Urban evolution | [
"Physics",
"Biology"
] | 5,618 | [
"Ecology terminology",
"Physical phenomena",
"Ecological processes",
"Earth phenomena"
] |
65,343,961 | https://en.wikipedia.org/wiki/THEMATICS | Theoretical Microscopic Anomalous Titration Curve Shapes (THEMATICS) is a computational method for predicting the biochemically active amino acids in a protein three-dimensional structure.
The method was developed by Mary Jo Ondrechen, James Clifton, and Dagmar Ringe. It is based on computed electrostatic and chemical properties of the individual amino acids in a protein structure. Specifically it identifies anomalous shapes in the theoretical titration curves of the ionizable amino acids. Biochemically active amino acids tend to have wide buffer ranges and non-sigmoidal titration patterns.
While the method predicts biochemically active amino acids successfully, it also provides input features to a machine learning predictor, Partial Order Optimum Likelihood (POOL).
References
Computational chemistry | THEMATICS | [
"Chemistry"
] | 161 | [
"Theoretical chemistry stubs",
"Theoretical chemistry",
"Computational chemistry",
"Computational chemistry stubs",
"Physical chemistry stubs"
] |
65,344,295 | https://en.wikipedia.org/wiki/Human%20Medicines%20Regulations%202012 | The Human Medicines Regulations 2012 in the United Kingdom were created, under statutory authority of the European Communities Act 1972 and the Medicines Act 1968 in 2012. The body responsible for their upkeep is the Medicines and Healthcare products Regulatory Agency. The regulations partially repealed the Medicines Act 1968 in line with EU legislation.
Amendments
In October 2020, the regulations were amended to expand the workforce eligible to administer COVID-19 vaccines, so enabling additional healthcare professionals to vaccinate the public. This was a temporary provision, but in January 2022 it was announced that this would be made permanent as would the provision for community pharmacy contractors to provide COVID-19 and flu vaccines “away from their normal registered premises”.
Regulation 174
Regulation 174 provides an exemption to the requirement for authorisation of Regulation 46, allowing for the sale or supply of any medicinal product to be temporarily authorised by the licensing authority (MHRA) in response to the suspected or confirmed spread of pathogenic agents, toxins, chemical agents or nuclear radiation.
References
External links
National Health Service
Pharmaceutics
Life sciences industry
Pharmacy
2012 establishments in the United Kingdom
Department of Health and Social Care
Medical regulation in the United Kingdom
Biotechnology
Statutory instruments of the United Kingdom
Health law in the United Kingdom | Human Medicines Regulations 2012 | [
"Chemistry",
"Biology"
] | 249 | [
"Pharmacology",
"Life sciences industry",
"Pharmacy",
"Biotechnology",
"nan"
] |
65,346,870 | https://en.wikipedia.org/wiki/NY%20Virginis | NY Virginis is a binary star about away. The primary belongs to the rare class of subdwarf B stars, being former red giants with their hydrogen envelope completely stripped by a stellar companion. The companion is a red dwarf star. The binary nature of NY Virginis was first identified in 1998, and the extremely short orbital period of , together with brightness variability on the timescale of 200 seconds was noticed, resulting in the identification of the primary star as a B-type subdwarf in 2003. Under a proposed classification scheme for hot subdwarfs it would be class sdB1VII:He1. This non-standard system indicates that it is a "normal" luminosity for a hot subdwarf and that the spectrum is dominated by hydrogen rather than helium.
Planetary system
In 2011, variations in the timing of the binary star's eclipses were used to infer the presence of a superjovian planet, NY Virginis (AB) b, on a wide orbit, with a second planet being suspected. A study in 2014 found that a two-planet model was preferred. The orbits of these two planets are near or at a 3:10 mutual orbital resonance. Another two-planet model with significant orbital eccentricity, updated to account for changes in eclipse timing not predicted by previous models, was published in 2019.
Studies in 2022 have noted that since planetary models generally fail to predict subsequent changes in eclipse timing, and the most recent two-planet model as of 2021 results in orbits that are unstable on an astronomically-short timescale.
However, in 2023 another model with circular orbits was proposed, which gives stability to the system. The same team also find that it is valid that there are exoplanets in the system creating the eclipe timing variations, and that the moderate eccentricites of the previous model likely caused the orbital instability.
References
Virgo (constellation)
Planetary systems with two confirmed planets
Algol variables
Multi-star planetary systems
J13384814-0201491
B-type subdwarfs
Very rapidly pulsating hot stars
M-type main-sequence stars
Virginis, NY | NY Virginis | [
"Astronomy"
] | 443 | [
"Virgo (constellation)",
"Constellations"
] |
65,348,263 | https://en.wikipedia.org/wiki/The%20Extermination%20of%20the%20American%20Bison | The Extermination of the American Bison is a book by William Temple Hornaday first published in 1889 by the Government Printing Office. It was reprinted from a report Hornaday wrote for the Smithsonian Institution in the years 1886–87.
Extermination contains an exhaustive account of bison ecology and the story of the near-entire destruction of the bison population in the United States. The book argues for the consequent necessity of protecting the small number of bison then in Yellowstone National Park.
The book is divided into three parts. The first relates to the habits, geographical distribution, and probable population of the bison before the European settlement of North America. The second describes the extermination of the animal by industrial-scale bison hunting. It argues that the speed of extermination has been increased by unnecessary slaughter and the lack of legal protection of the bison population, among other things. The third part describes the Smithsonian's 1886 expedition to Montana to obtain specimens for the National Museum of Natural History before bison went extinct in North America. A census of the animals known to exist in captivity on January 1, 1889, showed 256 specimens in the United States and abroad.
One contemporary writer notes that a number of scholars consider Extermination to be "the first important text of the American wildlife conservation movement".
See also
Conservation of American bison
References
Further reading
1889 non-fiction books
Natural history books
Environmental disasters in the United States
Nature conservation in the United States
Bison hunting
Smithsonian Institution publications
Environmental racism in the United States | The Extermination of the American Bison | [
"Biology"
] | 307 | [
"Wildlife conservation",
"Biodiversity"
] |
65,349,345 | https://en.wikipedia.org/wiki/Sterbenz%20lemma | In floating-point arithmetic, the Sterbenz lemma or Sterbenz's lemma is a theorem giving conditions under which floating-point differences are computed exactly.
It is named after Pat H. Sterbenz, who published a variant of it in 1974.
The Sterbenz lemma applies to IEEE 754, the most widely used floating-point number system in computers.
Proof
Let be the radix of the floating-point system and the precision.
Consider several easy cases first:
If is zero then , and if is zero then , so the result is trivial because floating-point negation is always exact.
If the result is zero and thus exact.
If then we must also have so . In this case, , so the result follows from the theorem restricted to .
If , we can write with , so the result follows from the theorem restricted to .
For the rest of the proof, assume without loss of generality.
Write in terms of their positive integral significands and minimal exponents :
Note that and may be subnormal—we do not assume .
The subtraction gives:
Let .
Since we have:
, so , from which we can conclude is an integer and therefore so is ; and
, so .
Further, since , we have , so that
which implies that
Hence
so is a floating-point number.
Note: Even if and are normal, i.e., , we cannot prove that and therefore cannot prove that is also normal.
For example, the difference of the two smallest positive normal floating-point numbers and is which is necessarily subnormal.
In floating-point number systems without subnormal numbers, such as CPUs in nonstandard flush-to-zero mode instead of the standard gradual underflow, the Sterbenz lemma does not apply.
Relation to catastrophic cancellation
The Sterbenz lemma may be contrasted with the phenomenon of catastrophic cancellation:
The Sterbenz lemma asserts that if and are sufficiently close floating-point numbers then their difference is computed exactly by floating-point arithmetic , with no rounding needed.
The phenomenon of catastrophic cancellation is that if and are approximations to true numbers and —whether the approximations arise from prior rounding error or from series truncation or from physical uncertainty or anything else—the error of the difference from the desired difference is inversely proportional to . Thus, the closer and are, the worse may be as an approximation to , even if the subtraction itself is computed exactly.
In other words, the Sterbenz lemma shows that subtracting nearby floating-point numbers is exact, but if the numbers one has are approximations then even their exact difference may be far off from the difference of numbers one wanted to subtract.
Use in numerical analysis
The Sterbenz lemma is instrumental in proving theorems on error bounds in numerical analysis of floating-point algorithms.
For example, Heron's formula
for the area of triangle with side lengths , , and , where is the semi-perimeter, may give poor accuracy for long narrow triangles if evaluated directly in floating-point arithmetic.
However, for , the alternative formula
can be proven, with the help of the Sterbenz lemma, to have low forward error for all inputs.
References
Computer arithmetic
Floating point
Numerical analysis | Sterbenz lemma | [
"Mathematics"
] | 679 | [
"Computational mathematics",
"Computer arithmetic",
"Arithmetic",
"Mathematical relations",
"Numerical analysis",
"Approximations"
] |
65,349,371 | https://en.wikipedia.org/wiki/Coocaa | Coocaa (; stylised as COOCAA), also known as Kukai, is a China-based smart TV brand that was founded in 2006. It was sequentially invested by iQIYI, Tencent, Baidu, and focuses on AIoTV. Owned by Shenzhen Skyworth-RGB Electronic Co., Ltd., its TV products feature Dolby Vision and full screen.
With headquarters in Shenzhen, Coocaa has ventured into Philippines and Malaysia. It was an official partner of the 2019 SEA Games. In November 2019, Coocaa attended the World TV Day event. The brand also has its own operating system called "Coocaa OS".
History
Coocaa TV shipments exceeded 1 million units in 2015. In June 2017, Tencent invested HK$344.28 million to acquire a 7.7% stake in Coocaa. In March 2018, Baidu invested $159.70 million to obtain an 11% stake in Coocaa.
As of April 2020, the total number of users of the Coocaa System amounted to approximately 50 million users, this figure reached 80 million up to October.
References
Smart TV
Chinese brands
2006 establishments in China
Consumer electronics brands
Products introduced in 2006 | Coocaa | [
"Technology"
] | 251 | [
"Multimedia",
"Smart TV"
] |
65,350,604 | https://en.wikipedia.org/wiki/TM%20%28triode%29 | The TM (from , also marketed as TM Fotos and TM Metal) was a triode vacuum tube for amplification and demodulation of radio signals, manufactured in France from November 1915 to around 1935. The TM, developed for the French Army, became the standard small-signal radio tube of the Allies of World War I, and the first truly mass-produced vacuum tube. Wartime production in France is estimated at no less than 1.1 million units. Copies and derivatives of the TM were mass-produced in the United Kingdom as Type R, in the Netherlands as Type E, in the United States and in Soviet Russia as P-5 and П7.
Development
Development of the TM was initiated by colonel Gustave-Auguste Ferrié, chief of French long-distance military communications (Télégraphie Militaire). Ferrié and his closest associate Henri Abraham were well informed about American research in radio and vacuum technology. They knew that Lee de Forest's audion and the British gas-filled lamp designed by H. J. Round were too unstable and unreliable for military service, and that Irving Langmuir's pliotron was too complex and expensive for mass production.
Shortly after the outbreak of World War I, a former Telefunken employee returning from the United States briefed Ferrié on the progress made in Germany and delivered samples of the latest American triodes, but again none of them met the demands of the Army. The problems were traced to insufficiently hard vacuum. Following suggestions made by Langmuire, Ferrié made a strategically correct decision to refine industrial vacuum pump technology that could guarantee sufficiently hard vacuum in mass production. The future French triode needed to be reliable, reproducible and inexpensive.
In October 1914 Ferrié dispatched Abraham and Michel Peri to Grammont incandescent lamp plant in Lyon. Abraham and Peri started with copying American designs. As was expected, the audion was unreliable and unstable, the pliotron and the first three original French prototypes were too complex. By trial and error, Abraham and Peri developed a simpler and inexpensive configuration. Their fourth prototype, which had vertically placed electrode assembly, was selected for mass production and was manufactured by Grammont from February to October of 1915. This triode, known as the Abraham tube, did not pass the test of field service: many tubes were damaged during transportation.
Ferrié instructed Peri to fix the problem, and two days later Peri and Jacques Biguet presented a modified design, with horizontally placed electrode assembly and the novel four-pin Type A socket (the original Abraham tube used an Edison screw with two additional flexible wires). In November 1915 the new triode was pressed into production and became known as the TM after the French service that developed it. Work by Ferrié and Abraham was nominated for the 1916 Nobel Prize in Physics. However, the patent was granted solely to Peri and Biguet, causing future legal disputes.
Design and specifications
The electrode assembly of the TM has nearly perfect cylindrical shape. The anode is a nickel cylinder, 10 mm in diameter and 15 mm long. Grid diameter varies from 4.0 to 4.5 mm; the Lyon plant made grids of pure molybdenum, the plant in Ivry-sur-Seine used nickel. The directly-heated cathode filament is a straight wire of pure tungsten, 0.06 mm in diameter.
Pure tungsten cathode reached proper emission level when heated to white incandescence, which required heating current of over 0.7 A at 4 V. The filament was so bright that in 1923 Grammont replaced clear glass envelope with dark blue cobalt glass. There were rumours that the company tried to discourage alleged use of radio tubes in place of lightbulbs, or that they tried to protect the eyes of radio operators. Most likely, however, dark glass was used to mask harmless but unsightly metal particles that were inevitably sputtered on the inner surface of the bulb.
A typical single-tube radio receiver of World War I used 40 V plate power supply (B battery) and zero bias on the grid (no C battery required). In this mode, the tube operated at 2 mA standing anode current, and had transconductance of 0.4 mA/V, gain (μ) of 10 and anode impedance of 25 kOhm. At higher voltages (i.e. 160 V on the anode and -2 V on the grid), standing plate current rose to 3...6 mA, with reverse grid current up to 1 μA. High grid currents, an inevitable consequence of primitive technology of the 1910s, simplified grid leak biasing.
The TM and its immediate clones were general-purpose tubes. In addition to their original radio receiving function, they were successfully employed in radio transmitters. A single Soviet-made P-5 configured as a class C radio frequency generator withstood 500 to 800 Volts plate voltage, and could deliver up to 1 W into the antenna, while a class A circuit could only deliver 40 mW. Audio frequency amplification in class A was feasible using arrays of parallel-connected TMs.
Lifetime of a genuine French-made TM, built in strict compliance with the design, did not exceed 100 hours. During the war, factories inevitably had to use substandard raw materials which resulted in substandard tubes. These were usually marked with a cross and suffered from unusually high noise levels and random early failures due to cracks in their glass envelopes.
Production history
In the course of World War I the TM became the tube of choice of allied armies. Demand exceeded capacity of the Lyon plant, so additional production was delegated to La Compagnie des Lampes plant in Ivry-sur-Seine. Total production volume is unknown, but it was certainly very high for the period. Estimates of daily wartime production vary from one thousand units (Lyon plant alone) to six thousand units. Estimates of total wartime production vary from 1.1 million units (0.8 million in Lyon and 0.3 million in Ivry-sur-Seine) to 1.8 million units for the Lyon plant alone.
British authorities quickly realized the benefits of the TM over domestic designs. In 1916 British Thomson-Houston developed necessary technology and tooling, and Osram-Robertson (which would later merge into Marconi-Osram Valve) began large-scale production. The British variants became known collectively as type R. In 1916-1917 the Osram plant produced two visually identical triode types: "hard" (high vacuum) R1, almost exactly copying the French original, and "soft" nitrogen-filled R2. The R2 was the last in the line of British gas-filled tubes; all subsequent designs from R3 to R7 were high vacuum tubes. Variants of Type R triodes were made to British order in the United States by Moorhead Laboratories. After the war, Philips launched production of the TM in the Netherlands as Type E. Cylindrical construction patented by Peri and Biguet became a standard feature of British high-power tubes, all the way to the 800-Watt T7X.
When the United States entered the war, annual output of the three largest American manufacturers could barely reach 80 thousand tubes of all types. This was too low for a fighting army; soon after deployment in France American Expeditionary Forces outran the quota and had to adopt French radio equipment. Thus, the AEF relied primarily on French-made tubes.
In Russia, Mikhail Bonch-Bruevich launched small-scale production of the TM in 1917. In 1923 Soviet authorities purchased French technology and tooling, and launched large-scale production at the Leningrad Electro-Vacuum Plant which would later merge into Svetlana. Soviet clones of the TM were named P-5 and П7, a high-efficiency thoriated-cathode variant was named Микро (Micro).
After World War I the general-purpose TM was gradually supplanted with new, specialized receiving and amplifying tubes. In the developed countries of the West the change was largely completed by the end of the 1920s, at which point it had started in less developed countries like the Soviet Union. There is no certain information on the end of production; according to Robert Champeix, production in France probably continued until 1935. In the late 20th century, replicas of the TM were released at least twice, by Rudiger Waltz in Germany (1980s) and by Ricardo Kron in Czech Republic (1992).
References
Sources
(Based on Champeix paper)
(Based on Champeix paper)
Vacuum tubes
French inventions
1915 in France
1915 in technology
1915 in radio
History of radio | TM (triode) | [
"Physics"
] | 1,797 | [
"Vacuum tubes",
"Vacuum",
"Matter"
] |
65,351,213 | https://en.wikipedia.org/wiki/Sony%20Xperia%205%20II | The Sony Xperia 5 II is an Android smartphone marketed and manufactured by Sony Mobile. Part of Sony's flagship Xperia series, the phone was announced on September 17, 2020. A less expensive and more compact variant of the Xperia 1 II, the Xperia 5 II belongs to Sony's handset lineup of 2020, which includes the flagship Xperia 1 II and the entry-level Xperia 10 II. The phone was released worldwide in October 2020.
The Xperia 5 II ships with support for 5G NR in Europe and Asia (making it Sony's second Xperia device to support this network), while the United States will ship with a 4G variant. Although 5G networks are supported, it only supports "sub-6" 5G, meaning it is not compatible with millimeter-wave (mmWave) networks.
Design
The Xperia 5 II retains Sony's signature square design that is seen on previous Xperia phones. It is built similarly to the Xperia 1 II, using anodized aluminum for the frame and Corning Gorilla Glass 6 for the screen and back panel, as well as IP65 and IP68 certifications for water resistance. The build has a pair of symmetrical bezels on the top and the bottom, where the front-facing dual stereo speakers and the front camera are placed. The left side of the phone contains a slot for a SIM card and a microSDXC card, while the right side contains a fingerprint reader embedded into the power button, a volume rocker and a shutter button. A dedicated Google Assistant button is located between the power and shutter buttons. The earpiece, front-facing camera, notification LED and various sensors are housed in the top bezel. The bottom edge has the primary microphone and USB-C port; the rear cameras are arranged in a vertical strip. The phone ships in four colours: Black, Gray, Blue and Pink.
Specifications
Hardware
The Xperia 5 II is powered by the Qualcomm Snapdragon 865 SoC and an Adreno 650 GPU, accompanied by 8 GB of LPDDR4X RAM. It has 128 or 256 GB of UFS internal storage, and microSD expansion is supported up to 1 TB with a hybrid dual-SIM setup. The display is smaller and has a lower resolution than the Xperia 1 II, using a 6.1 in 21:9 1080p (2520 × 1080) HDR OLED panel which results in a pixel density of 449 ppi. While the size and resolution are unchanged, it features a 120 Hz refresh rate. The camera system is similar to the Xperia 1 II in terms of hardware (a 12 MP primary lens, a 12 MP telephoto lens and a 12 MP ultrawide lens with an 8 MP front camera), but does not have a 3D iToF sensor. The telephoto lens has been upgraded from 2x to 3x optical zoom, and the ultrawide lens gains autofocus. Additionally, the lenses add ZEISS' T✻ (T-Star) anti-reflective coating. Software improvements include JPG+RAW shooting and HDR for 4K/120fps slow motion videos. The battery capacity has been increased to 4000mAh, the same as the 1 II despite the smaller body. USB Power Delivery 3.0 is supported at 21W over USB-C, although it lacks wireless charging capabilities. The device includes a 3.5mm audio jack, which was removed on its predecessor, as well as an active external amplifier.
Software
The Xperia 5 II runs on Android 10. Sony has also paired the phone's camera tech with a "Pro" mode developed by Sony's camera division CineAlta, whose features take after Sony's Alpha camera lineup.
Notes
References
External links
Android (operating system) devices
Discontinued flagship smartphones
Sony smartphones
Mobile phones introduced in 2020
Mobile phones with multiple rear cameras
Mobile phones with 4K video recording | Sony Xperia 5 II | [
"Technology"
] | 812 | [
"Discontinued flagship smartphones",
"Flagship smartphones"
] |
65,351,600 | https://en.wikipedia.org/wiki/Perron%27s%20irreducibility%20criterion | Perron's irreducibility criterion is a sufficient condition for a polynomial to be irreducible in —that is, for it to be unfactorable into the product of lower-degree polynomials with integer coefficients.
This criterion is applicable only to monic polynomials. However, unlike other commonly used criteria, Perron's criterion does not require any knowledge of prime decomposition of the polynomial's coefficients.
Criterion
Suppose we have the following polynomial with integer coefficients
where . If either of the following two conditions applies:
then is irreducible over the integers (and by Gauss's lemma also over the rational numbers).
History
The criterion was first published by Oskar Perron in 1907 in Journal für die reine und angewandte Mathematik.
Proof
A short proof can be given based on the following lemma due to Panaitopol:
Lemma. Let be a polynomial with . Then exactly one zero of satisfies , and the other zeroes of satisfy .
Suppose that where and are integer polynomials. Since, by the above lemma, has only one zero with modulus not less than , one of the polynomials has all its zeroes strictly inside the unit circle. Suppose that are the zeroes of , and . Note that is a nonzero integer, and , contradiction. Therefore, is irreducible.
Generalizations
In his publication Perron provided variants of the criterion for multivariate polynomials over arbitrary fields. In 2010, Bonciocat published novel proofs of these criteria.
See also
Eisenstein's criterion
Cohn's irreducibility criterion
References
Polynomials
Theorems in algebra | Perron's irreducibility criterion | [
"Mathematics"
] | 335 | [
"Theorems in algebra",
"Polynomials",
"Mathematical problems",
"Mathematical theorems",
"Algebra"
] |
65,351,650 | https://en.wikipedia.org/wiki/Neo-colonial%20science | Neo-colonial research or neo-colonial science, frequently described as helicopter research, parachute science or research, parasitic research, or safari study, is when researchers from wealthier countries go to a developing country, collect information, travel back to their country, analyze the data and samples, and publish the results with no or little involvement of local researchers. A 2003 study by the Hungarian Academy of Sciences found that 70% of articles in a random sample of publications about least-developed countries did not include a local research co-author.
Frequently, during this kind of research, the local colleagues might be used to provide logistics support as fixers but are not engaged for their expertise or given credit for their participation in the research. Scientific publications resulting from parachute science frequently only contribute to the career of the scientists from rich countries, thus limiting the development of local science capacity (such as funded research centers) and the careers of local scientists. This form of "colonial" science has reverberations of 19th century scientific practices of treating non-Western participants as "others" in order to advance colonialism—and critics call for the end of these extractivist practices in order to decolonize knowledge.
This kind of research approach reduces the quality of research because international researchers may not ask the right questions or draw connections to local issues. The result of this approach is that local communities are unable to leverage the research to their own advantage. Ultimately, especially for fields dealing with global issues like conservation biology which rely on local communities to implement solutions, neo-colonial science prevents institutionalization of the findings in local communities in order to address issues being studied by scientists.
Effects
The use of helicopter research has also led to a stigma of research within minority groups; some going so far as to deny research within their communities. Such safari studies lead to long-term negative effects for the scientific community and researchers, as distrust develops within peripheral communities.
Donor robbery
Funds for research in developing countries are often provided by bilateral and international academic and research programmes for sustainable development. Through 'donor robbery' a large proportion of such international funds may end up in the wealthier countries via consultancy fees, laboratory costs in rich universities, overhead or purchase of expensive equipment, hiring expatriates and running "enclave" research institutes, depending on international conglomerates.
Use of open data
The current tendency of freely availing research datasets may lead to exploitation of, and rapid publication of results based on data pertaining to developing countries by rich and well-equipped research institutes, without any further involvement and/or benefit to local communities; similarly to the historical open access to tropical forests that has led to the disappropriation ("Global Pillage") of plant genetic resources from developing countries.
Professional discourse
In certain fields of research, such as global public health, both the journals and professionals creating the field have defined much of their work under colonial structures and assumptions. This in turn prevents participation in the field from early in the process, even before authorship or credit is given during the publishing representation of editorial boards of journals publishing in environmental sciences and public health, with a vast majority of editors based in high-income countries despite the global scope of the journals' fields.
Mitigation
Some journals and publishers are implementing policies that should mitigate the impact of parachute science. One of the conditions for publication set by the journal Global Health Action is that, "Articles reporting research involving primary data collection will normally include researchers and institutions from the countries concerned as authors, and include in-country ethical approval." Similarly The Lancet Global Health placed restriction encouraged submissions to review their practices for including local participants. Similarly in 2021, PLOS announced a policy that required changes in reporting for researchers working in other countries.
A number of research communities are putting protocols in place for indigenous health information. In the US, the Cherokee Nation established a specific Institutional Review Board, aiming at ensuring the protection of the rights and welfare of tribal members involved in research projects. The Cherokee Nation IRB does not allow helicopter research. The Human Heredity and Health in Africa (H3Africa) Initiative launched guidelines for working with genetic information from the continent in 2018.
An Ethiopian soil scientist, Mitiku Haile, suggests that such "free riding" should be "condemned by all partners and, if found, should be brought to the attention of the scientific community and the international and national funding agencies".
Also in Africa, since the outbreak of the coronavirus pandemic in 2020, travel restrictions on international scholars tend to local scientists stepping up to lead research.
Examples by field
Examples of neo-colonial approaches to science include:
In the medical world: "A popular term for a clinical or epidemiologic research project conducted by foreign scientists who use local contacts to gain access to a population group and obtain samples"
In anthropology, particularly when related to peripheral ethnic groups: "Any investigation within the community in which a researcher collects data, leaves to disseminate it, and never again has contact with the tribe."
In geosciences, a 2020 study found that 30% of studies about Africa contained an African author. (See also: Ubirajara jubatus.)
When scientists from a central, dominant ethnic or sociological group conduct research in areas where minority groups are living (often peripheral areas), there is also a risk for helicopter research, though it may not appear directly from the academic affiliation of the researchers. For instance, within the United States, it has been used primarily in the study of Native Americans.
Climate change
An analysis of research money from 1990 to 2020 for climate change, found that 78% of research money for research on Climate change in Africa, was spent in European and North American institutions and more was spent for former British colonies than other countries. This in turn both prevents local researchers from doing groundbreaking work, because they don't have the funding for experimental activities and reduces investment in local researchers ideas and in topics important to the Global South, such as climate change adaptation.
Soil science
Soil scientists have qualified helicopter research as a perpetuation of "colonial" science. Typically researchers from rich countries would come to establish soil profile pits or collect soil and peat samples, which is often more easily done in poor countries given the availability of cheap labour and goodwill of villagers to dig a pit on their land against small payment. The profile will be described and samples taken with the help of local people, possibly also university staff. In case of helicopter research, the outcomes are then published such as discovery in tropical peatlands, sometimes in high-level journals without the involvement of local colleagues. "Overall, helicopter research tends to produce academic papers that further the career of scientists from developed countries, but provide little practical outcomes for nations where the studies are conducted, nor develop the careers of their local scientists."
Coral Reef research
A 2021 study in Current Biology quantified the amount of parachute research happening in coral reef studies and found such approaches to be the norm.
Examples by region
Europe
The 2015 description of Tetrapodophis was performed by three European scientists. When the Brazilan newspaper Estadão – Brazil being the country where the fossil hails from – questioned lead researcher David M. Martill, he replied "It should be fossils for all. No countries existed when the animals were fossilized. [..] what difference would it make [partnering with Brazilian scientists]? I mean, do you want me also to have a black person on the team for ethnicity reasons, and a cripple and a woman, and maybe a homosexual too, just for a bit of all round balance? [..] Now I don't work in Brazil. But I still work on Brazilian fossils. There are hundreds of them in museums all over Europe, America and in Japan."
Central Africa
A 2009 study found that Europeans participated in 77% of regionally co-authored papers in Central African countries. Even though local authors are credited with the work, they aren't always given participatory roles in the final production of the research itself—instead playing roles in fieldwork.
Indonesia
In April 2018, a publication about Indonesia's Bajau people received great attention. These "sea nomads" had a genetic adaptation resulting in large spleens that supply additional oxygenated red blood cells. A month later this publication was criticised by Indonesian scientists. Their article in Science questioned the ethics of scientists from the United States and Denmark who took DNA samples of the Bajau people and analyzed them, without much involvement of Bajau or other Indonesian people.
See also
Academic dishonesty
Bioethics
Biopiracy
Bullying in academia
Committee on Publication Ethics
Conflicts of interest in academic publishing
Research ethics
Research integrity
Scientific method
References
Misconduct
Science in society | Neo-colonial science | [
"Technology"
] | 1,761 | [
"Ethics of science and technology"
] |
65,352,233 | https://en.wikipedia.org/wiki/Timothy%20D.%20Lash | Timothy D. Lash (born 13 October 1953) is an English-born chemist. He moved to the United States and began teaching at Illinois State University in 1984. Lash is known for his contributions to synthetic porphyrin chemistry.
Career
Timothy D. Lash was born on 13 October 1953, in Salisbury, England.
He completed B.Sc. (Hon.) degree in chemistry from the University of Exeter in 1975 and his MS in organic chemistry from University of Wales, College of Cardiff. In 1979 he received his Ph.D. in organic chemistry from same university under the guidance of A. H. Jackson.
Lash joined the Department of Chemistry at Illinois State University in 1984 and assumed the rank of professor in 1993. In 2000, he was designated as a distinguished professor, the highest honor awarded by the university. In 2004, Lash was selected as “Chemist of the Year” for the Illinois Heartland section of the American Chemical Society.
Publications
T. D. Lash, “Carbaporphyrins and Related Systems. Synthesis, Characterization, Reactivity and Insights into the Nature of Porphyrinoid Aromaticity” in Handbook of Porphyrin Science – With Applications to Chemistry, Physics, Material Science, Engineering, Biology and Medicine, Ed. K. M. Kadish, K. M. Smith and R. Guilard, World Scientific Publishing, Singapore, 2012, Volume 16, Chapter 74, pp 1–329.
T. D. Lash, “Synthesis of Novel Porphyrin Chromophores” in The Porphyrin Handbook, Ed. K. M. Kadish, K. M. Smith and R. Guilard, Academic Press: San Diego, CA, 2000, Volume 2: Heteroporphyrins, Expanded Porphyrins and Related Macrocycles, Chapter 10, pp 125–199.
T. D. Lash, “Synthesis of porphyrins with exocyclic rings from cycloalkenopyrroles” in Advances in Nitrogen Heterocycles, Volume 1, Ed. C. J. Moody, JAI Press Inc., 1995, pp 19–69.
T. D. Lash, “Heteroporphyrins and Carbaporphyrins” in Porphyrins for the 21st Century, Volume 1 – Fundamentals, Ed. P. Brothers and M. Senge, Wiley, 2016, in press.
References
External links
https://chemistry.illinoisstate.edu/faculty_staff/profile.php?ulid=tdlash#fs-tabs-accord3
https://academictree.org/chemistry/publications.php?pid=687994
Living people
1953 births
Illinois State University faculty
Alumni of the University of Exeter
Alumni of the University of Wales
20th-century English chemists
English chemists
People from Salisbury
English emigrants to the United States
21st-century British chemists
British organic chemists
British expatriate academics in the United States
Alumni of Cardiff University | Timothy D. Lash | [
"Chemistry"
] | 617 | [
"Organic chemists",
"British organic chemists"
] |
65,353,050 | https://en.wikipedia.org/wiki/Halvor%20Bothner-By | Halvor Bothner-By (August 20, 1938 - June 13, 2014) was a telecommunication engineer of the Norwegian Telecommunications Administration.
He was a rapporteur on packet switching for the CCITT. As such, he chaired the group that, in March 1975, proposed to the CCITT Recommendation X.2x on virtual circuits to be offered by public networks. After its unanimous approval at the May 1976 CCITT plenary, it became the well-known protocol X.25.
He was also renowned for having coined the term datagram in the early seventies on a train between Paris and Rennes on the way to attend a CEPT Rapporteur meeting.
References
1938 births
2014 deaths
Telecommunications engineers
20th-century Norwegian engineers
X.25 | Halvor Bothner-By | [
"Engineering"
] | 151 | [
"Telecommunications engineering",
"Telecommunications engineers"
] |
75,290,234 | https://en.wikipedia.org/wiki/HD%20200073 | HD 200073 (HR 8046; 43 G. Microscopii) is a solitary star located in the southern constellation Microscopium northwest of Zeta Microscopii. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.94. The object is located relatively close at a distance of 227 light-years based on Gaia DR3 parallax measurements, but it is receding with a heliocentric radial velocity of . At its current distance, HD 200073's brightness is diminished by an interstellar extinction of 0.13 magnitudes and it has an absolute magnitude of +1.79. It has a relatively high proper motion across the celestial sphere, moving at a rate of 213 mas/yr.
HD 200073 has a stellar classification of K2 III, indicating that it is an evolved K-type giant that has exhausted hydrogen at its core and left the main sequence. Astronomer David Stanley Evans gave a class of K0 IV, indicating that it is a slightly evolved subgiant that is ceasing hydrogen fusion at its core. HD 200073 is currently on the red giant branch, fusing hydrogen in a shell around an inert helium core. It has a comparable mass to the Sun but at the age of 8.79 billion years, it has expanded to 9.15 times the radius of the Sun. It radiates 28.8 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of . HD 200073 is slightly metal-deficient with an iron abundance of [Fe/H] = −0.13 or 74.1% of the Sun's. It spins modestly with a projected rotational velocity of .
References
K-type giants
Microscopium
Microscopii, 43
CD-39 14079
200073
103836
8046
00115011683 | HD 200073 | [
"Astronomy"
] | 401 | [
"Microscopium",
"Constellations"
] |
75,290,366 | https://en.wikipedia.org/wiki/Raphamin | Raphamin is a drug developed as an antiviral. It is manufactured by the Russian company Materia Medica.
References
Antiviral drugs | Raphamin | [
"Chemistry",
"Biology"
] | 32 | [
"Pharmacology",
"Antiviral drugs",
"Medicinal chemistry stubs",
"Pharmacology stubs",
"Biocides"
] |
75,290,411 | https://en.wikipedia.org/wiki/Prospekta | Prospekta is a nootropic drug reported to act on the S100 proteins. It was developed by the company Materia Medica and approved in Russia for the treatment of ADHD in 2022. It was also studied for vascular dementia.
References
Nootropics | Prospekta | [
"Chemistry"
] | 59 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
75,293,449 | https://en.wikipedia.org/wiki/Thulium-170 | Thulium-170 (170Tm or Tm-170) is a radioactive isotope of thulium proposed for use in radiotherapy and in radioisotope thermoelectric generators.
Properties
Thulium-170 has a binding energy of per nucleon and a half-life of . It decays by β− decay to 170Yb about 99.869% of the time, and by electron capture to 170Er about 0.131% of the time. About 18.1% of β− decays populate a narrow excited state of 170Yb at (), and this is the main X-ray emission from 170Tm; lower bands are also produced through X-ray fluorescence at 7.42, 51.354, 52.389, 59.159, 59.383, and 60.962 keV.
The ground state of thulium-170 has a spin of 1−. The charge radius is , the magnetic moment is , and the electric quadrupole moment is .
Proposed applications
As a rare-earth element, thulium-170 can be used as the pure metal or thulium hydride, but most commonly thulium oxide due to the refractory properties of that compound. The isotope can be prepared in a medium-strength reactor by neutron irradiation of natural thulium, which has a high neutron capture cross section of .
Medicine
In 1953, the Atomic Energy Research Establishment introduced thulium-170 as a candidate for radiography in medical and steelmaking contexts, but this was deemed unsuitable due to the predominant high-energy bremsstrahlung radiation, poor results on thin specimens, and long exposure times. However, 170Tm has been proposed for radiotherapy because the isotope is simple to prepare into a biocompatible form, and the low-energy radiation can selectively irradiate diseased tissue without causing collateral damage.
Radiothermal generator
As the oxide (), thulium-170 has been proposed as a radiothermal source due to it being safer, cheaper, and more environmentally friendly than commonly used isotopes such as plutonium-238. The heat output from a 170Tm source is initially much greater than from a 238Pu source relative to mass, but it declines rapidly due to its shorter half-life.
References
Isotopes of thulium | Thulium-170 | [
"Chemistry"
] | 486 | [
"Isotopes of thulium",
"Isotopes"
] |
75,294,018 | https://en.wikipedia.org/wiki/Paltusotine | Paltusotine is a selective somatostatin receptor type 2 (SST2) agonist in development for the treatment of acromegaly and certain neuroendocrine tumors. It is a small molecule delivered orally.
References
Quinolines
Benzonitriles
Phenols
Piperidines
Amines
Fluoroarenes | Paltusotine | [
"Chemistry"
] | 71 | [
"Pharmacology",
"Functional groups",
"Medicinal chemistry stubs",
"Amines",
"Pharmacology stubs",
"Bases (chemistry)"
] |
75,297,354 | https://en.wikipedia.org/wiki/NGC%205273 | NGC 5273 is a lenticular galaxy located away in the northern constellation of Canes Venatici. This galaxy was discovered by William Herschel on May 1, 1785. It is positioned ° to the southeast of the star 25 Canum Venaticorum.
The morphological classification of this galaxy is SA0(s), indicating it is lenticular in form. It displays a faint, unbarred spiral structure within a generally elliptical profile. NGC 5273 is classified as a type 1.5 Seyfert galaxy, with the X-ray emission from its active galactic nucleus undergoing significant absorption. However, data collected between the year 2000 and 2022 suggest this is a changing–look Seyfert, with the type ranging from 1 to 1.8/1.9. The activity level shows strong variability, allowing reverberation mapping of the supermassive black hole at the core. This object has an estimated mass of .
References
Further reading
Lenticular galaxies
Seyfert galaxies
Canes Venatici
5273
48521
08675
Astronomical objects discovered in 1785
Discoveries by William Herschel | NGC 5273 | [
"Astronomy"
] | 231 | [
"Canes Venatici",
"Constellations"
] |
75,297,794 | https://en.wikipedia.org/wiki/Executive%20Order%2014110 | Executive Order 14110, titled Executive Order on Safe, Secure, and Trustworthy Development and Use of Artificial Intelligence (sometimes referred to as "Executive Order on Artificial Intelligence") was the 126th executive order signed by former U.S. President Joe Biden. Signed on October 30, 2023, the order defines the administration's policy goals regarding artificial intelligence (AI), and orders executive agencies to take actions pursuant to these goals. The order is considered to be the most comprehensive piece of governance by the United States regarding AI. It was rescinded by U.S. President Donald Trump within hours of his assuming office on January 20, 2025.
Policy goals outlined in the executive order pertain to promoting competition in the AI industry, preventing AI-enabled threats to civil liberties and national security, and ensuring U.S. global competitiveness in the AI field. The executive order required a number of major federal agencies to create dedicated "chief artificial intelligence officer" (chief AI officer) positions within their organizations.
Background
The drafting of the order was motivated by the rapid pace of development in generative AI models in the 2020s, including the release of large language model ChatGPT. Executive Order 14110 is the third executive order dealing explicitly with AI, with two AI-related executive orders being signed by then-President Donald Trump.
The development of AI models without policy safeguards has raised a variety of concerns among experts and commentators. These range from future existential risk from advanced AI models to immediate concerns surrounding current technologies' ability to disseminate misinformation, enable discrimination, and undermine national security.
In August 2023, Arati Prabhakar, the director of the Office of Science and Technology Policy, indicated that the White House was expediting its work on executive action on AI. A week prior to the executive order's unveiling, Prabhakar indicated that Office of Management and Budget (OMB) guidance on the order would be released "soon" after.
Policy goals and provisions
The order has been characterized as an effort for the United States to capture potential benefits from AI while mitigating risks associated with AI technologies. Upon signing the order, Biden stated that AI technologies were being developed at "warp speed", and argued that to "realize the promise of AI and avoid the risk, we need to govern this technology".
Policy goals outlined by the order include the following:
Promoting competition and innovation in the AI industry
Upholding civil and labor rights and protecting consumers and their privacy from AI-enabled harms
Specifying federal policies governing procurement and use of AI
Developing watermarking systems for AI-generated content and warding off intellectual property theft stemming from the use of generative models
Maintaining the nation's place as a global leader in AI
Impact on agencies
Creation of chief AI officer positions
The executive order required a number of large federal agencies to appoint a chief artificial intelligence officer, with a number of departments having already appointed a relevant officer prior to the order. In the days following the order, news publication FedScoop confirmed that the General Services Administration (GSA) and the United States Department of Education appointed relevant chief AI officers. The National Science Foundation (NSF) also confirmed it had elevated an official to serve as its chief AI officer.
Department responsibilities
Under the executive order, the Department of Homeland Security (DHS) was responsible for developing AI-related security guidelines, including cybersecurity-related matters. The DHS will also work with private sector firms in sectors including the energy industry and other "critical infrastructure" to coordinate responses to AI-enabled security threats. Executive Order 14110 mandated the Department of Veterans Affairs to launch an AI technology competition aimed at reducing occupational burnout among healthcare workers through AI-assisted tools for routine tasks.
The order also mandated the Department of Commerce's National Institute of Standards and Technology (NIST) to develop a generative artificial intelligence-focused resource to supplement the existing AI Risk Management Framework.
Analysis
The executive order has been described as most comprehensive piece of governance by the United States government pertaining to AI. Earlier in 2023 prior to the signing of the order, the Biden administration had announced a Blueprint for an AI Bill of Rights, and had secured non-binding AI safety commitments from major tech companies. The issuing of the executive order comes at a time in which lawmakers including Senate Majority Leader Chuck Schumer have pushed for legislation to regulate AI in the 118th United States Congress.
According to Axios, despite the wide scope of the executive order, it notably does not touch upon a number of AI-related policy proposals. This includes proposals for a "licensing regime" to government advanced AI models, which has received support from industry leaders including Sam Altman. Additionally, the executive order does not seek to prohibit 'high-risk' uses of AI technology, and does not aim to mandate that tech companies release information surrounding AI systems' training data and models.
Reception
Political and media reception
The editorial board of the Houston Chronicle described the order as a "first step toward protecting humanity". The issuing of the order received praise from Democratic members of Congress, including Senator Richard Blumenthal (D-CT) and Representative Ted Lieu (D-CA). Representative Don Beyer (D-VA), who leads the House AI Caucus, praised the order as a "comprehensive strategy for responsible innovation", while arguing that Congress must take initiative to pass legislation on AI.
The draft of the order received criticism from Republican Senator Ted Cruz (R-TX), who described it as creating "barriers to innovation disguised as safety measures".
Public reception
Polling from the AI Policy Institute showed that 69% of all voters support the executive order, while 15% oppose it. Breaking it down by party, support was at 78% for democrats, 65% for independents, and 64% for Republicans.
Industry reception
The executive order received strong criticism from the Chamber of Commerce as well as tech industry groups including NetChoice and the Software and Information Industry Association, all of which count "Big Tech" companies Amazon, Meta, and Google as members. Representatives from the organizations argued that the executive order threatens to hinder private sector innovation.
Civil society reception
According to CNBC, a number of leaders of advocacy organizations praised the executive order for its provisions on "AI fairness", while simultaneously urging congressional action to strengthen regulation. Maya Wiley, president and CEO of the Leadership Conference on Civil and Human Rights, praised the order while urging Congress to take initiative to "ensure that innovation makes us more fair, just, and prosperous, rather than surveilled, silenced, and stereotyped". A representative from the American Civil Liberties Union (ACLU) praised provisions of the order centered on combating AI-enabled discrimination, while also voiced concern over sections of the order focused on law enforcement and national security.
Second Trump administration
Hours after his inauguration as the 47th president of the United States, Donald Trump rescinded the order, labeling it, among several other of Biden's executive orders and actions, as "unpopular, inflationary, illegal, and radical practices".
See also
National Security Memorandum on Artificial Intelligence
List of executive actions by Joe Biden
References
2023 in American politics
Executive orders of Joe Biden
Regulation of artificial intelligence | Executive Order 14110 | [
"Technology"
] | 1,478 | [
"Computing and society",
"Regulation of artificial intelligence"
] |
75,297,812 | https://en.wikipedia.org/wiki/Freeze-fracture | Freeze-fracture is a natural occurrence leading to processes like erosion of the earths crust or simply deterioration of food via freeze-thaw cycles. To investigate the process further freeze-fracture is artificially induced to view in detail the properties of materials. Fracture during freezing is often the result of crystallizing water which results in expansion. Crystallization is also a factor leading to chemical changes of a substance due to changes in the crystal surroundings called eutectic formation.
Imaging the fractured surface of a frozen substance allows the interior of the structure to be investigated as illustrated by the picture of a fractured piece of glacier called an iceberg. By photographing at high magnifications more can be learnt about the fractured object's substructure and the changes in the object that occur during freezing. When imaging fractured surfaces in detail, changes occurring during and immediately after fracture as well as sample preparation, must be taken into account if trying to infer the unbroken material's structure. The often relatively cold temperatures needed to make an object solid enough to fracture, and the fracture process itself, stress and deform the material. Imaging of fine detail under sub-zero conditions is difficult. The material will start to warm again when removed to a position for photography. Ambient gases, often water vapor, will condense on the cold surfaces, reacting with them, obscuring detail and further warming the object allowing it to reshape.
Freezing considerations
Freezing of a substance is a relative term, often relative to ambient temperatures. Freezing something from liquid or gas phase to a solid allows fracture but has different effects depending on the material involved and how quickly it is frozen. Freezing things slowly allows the material time to re-arrange itself internally. In the example of water, ice forming slowly results in larger crystals leading to a clear glass like substance. If frozen quickly as with snow, the crystals are smaller and less organized, scattering light and appearing white.
Elastic materials
Elastic solids generally become less elastic the cooler they get, making fracturing easier. For example, plastic hoses are flexible on hot days and less flexible and prone to cracking on cold days. Storage of critical items such as blood products in plastic bags must take into account the effect of freezing on the blood but also the changing plasticity of the storage bags. While many synthetic and natural polymers become progressively less elastic with reducing temperature they do not usually crystallize, unless they also contain a free liquid such as water in plants and soils or plasticizers in plastics.
Liquids
Liquids reduced in temperature will become solid enough to be fractured. The abundance of water on earth and particularly in living organisms and soils means frozen water often provides the rigidity needed for and otherwise less brittle object to fracture. While the water increases the rigidity of an object to allow it to be fractured, the formation of ice crystals within an object can also cause significant damage to structures which were previously intact. Changes in the eutectic around the forming crystals is also significant which can be disadvantageous, or used in the case of cooling solder advantageous. Freeze-fracture can occur as part of the freezing process, particularly with liquids that expand as they crystallize such as water. Such fracture is termed pre-fracture.To reduce damage from crystallization cryopreservatives which reduce ice crystal damage are often used but may themselves be toxic to living cells in the concentrations required. For small objects, freezing of liquids can be rapid enough for limited or no crystallization. In the case of water, very rapid freezing leads to vitreous amorphous ice rather than crystalline ice resulting in no detectable damage.
Solids
Perhaps counterintuitively, solids also change into different states when frozen. You may say they become more solid. For example, iron in its various forms will become more brittle at lower temperatures. Steels exhibit low temperature brittleness with a transition temperature from ductile to brittle fracture (TTDB) that varies from about −100 °C to about +100 °C depending on the alloy composition and processing. As the solids change with temperature so does the way they fracture.
Gases
Gases cooled sufficiently will become solid enough to fracture as well, such as with solid carbon dioxide also known as dry ice. Since gases have little structure when used under normal conditions there are currently no investigations into their solid phase structures using freeze-fracture. The requirement for freeze-fracture studies may increase with extra-planetary objects having surface temperatures cold enough for elements that are gases on earth to be naturally solid. Currently only the unfractured structures are being investigated such as solid carbon dioxide on the moon or solid methane and nitrogen on pluto.
Fracturing considerations
The energy of the fracture
To split a material into two pieces requires the material to be put under enough stress to break it. The amount of stress applied to an object prior to its fracture will determine the amount of energy available for the fracture to take place. Excessive stress results in multiple almost simultaneous fractures, as when shattering a sheet of glass with a hammer. Sufficient but not too much stress normally results in a single fracture. Even with a single fracture any slight excess in stress will lead to fracture that propagates more quickly with more energy and higher temperatures at the fracture face. The higher energy can also result distortions called plastic deformation or even in minute secondary fractures that break fragments off the main fracture face. If the stress is less focused a larger volume will be stressed leading to a slower propagation of the fracture with lower temperatures at the fracture face. Force in excess of that required for a single fracture plane to form is usually released as a combination of significant heating, plastic deformation and secondary fracture.
Temperature
Once cooled sufficiently to fracture, a sample is often cooled further. Stressing and fracturing a sample produces considerable heat, easily enough to thaw a sample again if the temperature is not well below the melting point.
Applications of Freeze-fracture
Here are a few visible examples of freeze-fracture being used directly in our daily lives. There are also less known applications of freeze-fracture knowledge. Better know examples relate to preventing freeze-fracture damage to water supply pipes or engine cooling systems in colder climates.
Daily lives
Ice for cooling
A very common requirement in many peoples' lives is using ice to keep things cool. Large blocks of ice were once the most common way of transporting ice.Once transported the ice would be later fractured into smaller pieces to make it practical to use. Today ice machines produced ready to use ice or ice cubes fractured by blending them into drinks such as a slushy or foods that contain fractured ice such as Ais kacang.
Tempered glass
Tempered glass has its exterior surface rapidly cooled from the liquid state so that it is frozen solid while the center of the glass is still liquid. As a result, the glass becomes highly stressed. When a single fracture is initiated the considerable stored energy in the prestressing is released. The sudden release of the energy fractures the entire pane into small less damaging pieces, as with a car windscreen.
Engineering
For practical purposes most devices manufactured have an "operating temperature". Often these relate to fragility induced by lowering temperatures increasing the likely-hood of prefracture or fracture.
Steel
Iron and its various alloys including steel, undergo changes in their resistance to fracturing with temperature. These changes can occur at higher temperatures as the steel solidifies during manufacture and also again at lower temperatures below 100 °C including below the freezing point of water at 0 °C. This has implications in the design and building of steel civil engineering structures such as bridges, buildings and pipes.
Composite materials
Freeze-thaw cycles of composite materials can weaken them. Moisture within composite materials has been modeled to try and predict the effects of water freezing with composite materials. As a widely used composite material, concrete is also an important material susceptible to freeze-fracture.
Chemistry
Composite material substructure
Materials and colloid sciences use freeze-fracture techniques to investigate the nature of more complex substances. Even without the visualizing the atoms and molecules the shapes and textures of the interface between reacting substances will have an impact on how they behave and react with each other.
Solder
Eutectic solders rely on the re-distribution of chemistry within the solder as they cool from liquid to solid. This can be taken advantage of to allow less toxic solders lower temperature solders that still bind well enough to prevent fracturing under operating conditions.
Biology
The idea of looking at the detail of biological cells and proteins in detail, without chemical fixation, plastic or wax embedding and chemical staining prior to sectioning resulted in extensive use of freeze-fracture microscopy in biology.
Freeze-fracture-replication
The first documented systematic visualization a frozen, fractured surface to look at the structure of the fracture face itself was done in the mid-1950s. Russel L. Steere was looking at virus particles and became concerned that conventional preparation techniques for electron microscopy, which included dehydration and more, may be altering the virus structure. While acknowledging freezing the sample would also cause changes he considered using it would give a different view. A "planed surface" was created on the frozen material using a knife. Due to the conditions required for the transmission electron microscope at the time the rapidly frozen and fractured virus itself could not be viewed directly. Instead Steere made a carbon re-enforced chromium replica of the fractured surface based on a procedure devised by others. Steere overcame the problem of ice crystals forming on the fractured viruses by etching them away as done by others in 1955 prior to making the copy for viewing. The additional etching step adds additional variations to the appearance of the original fractured surface but is essential to get rid of the condensates from the surface.
Commercialization of biological freeze-fracture
With the principles of visualizing a freeze-fractured surface for electron microscopy established, Moore automated and commercialized the Freeze-Fracture-Etch-Replication method in 1961 calling it "Steer's freeze-etching method". Believing a sharp knife was required to achieve a controlled fracture he used a microtome in a vacuum chamber to fracture the specimens. Much cheaper, non-commercial alternatives which did not rely on a microtome or etching to clean the fracture face were later established. The technique "Freeze-Fracture Replication", rather than Steere and Moore's Freeze-Fracture Etching replication began to be used for the first time in this context. Adequate shielding from contamination in the vacuum required for replication meant etching was not required to clean the fracture face. For the Bullivant & Ames method cheaply modified standard coating machines already routinely used in electron microscope laboratories, initially using a Meccano set. For smaller electron microsopy labs these could be more easily used than a large, specialized, commercial piece of freeze-fracture etch replication equipment. The method also allowed for much greater variations to the way the specimens could be fractured.
Viewing inside membranes
During the 1960s-1980's it became apparent that the cell's lipid bilayer was shown to split into two halves revealing the interior when fractured under suitable conditions. Freeze-fracture was the only method to give a planar view of the membrane interior so some effort was needed to establish what aspects of a membrane interior image were native to the biology and which were produced by the freezing, fracturing and replication processes. Adequate explanations as to why the two fracture halves were not always complementary and why the fracture plane sometimes went between the lipid bilayer and not other times were found through the use of additional freeze-fracture techniques. By 1989 the identity of "bumps" in the membrane as intramembrane protein particles was also established using a further modification of the basic freeze-fracture technique called freeze-fracture replica immunolabelling (FRIL).
References
Cell biology
Microscopy
Biological techniques and tools | Freeze-fracture | [
"Chemistry",
"Biology"
] | 2,384 | [
"Cell biology",
"nan",
"Microscopy"
] |
75,297,898 | https://en.wikipedia.org/wiki/Woodpecker%20Column | Woodpecker Column is a public artwork by the Canadian artist collective FASTWÜRMS, installed by the South Building of the Metro Toronto Convention Centre, in Toronto, Ontario, Canada. The 98-foot-tall (30 meters) black steel column was installed in 1997 and depicts a pileated woodpecker and a yellow-bellied sapsucker. The two birds are 6.5 feet (two meters) tall.
References
External links
Woodpecker Column at ArtWalk
1997 establishments in Ontario
1997 sculptures
Outdoor sculptures in Toronto
Sculptures of birds in Canada
Statues in Ontario
Colossal statues | Woodpecker Column | [
"Physics",
"Mathematics"
] | 118 | [
"Quantity",
"Colossal statues",
"Physical quantities",
"Size"
] |
75,297,967 | https://en.wikipedia.org/wiki/Eta%20Fornacis | Eta Fornacis may refer to three stars in the constellation of Fornax.
Eta1 Fornacis
Eta2 Fornacis
Eta3 Fornacis
Fornacis, Eta
Fornax | Eta Fornacis | [
"Astronomy"
] | 42 | [
"Fornax",
"Constellations"
] |
75,298,118 | https://en.wikipedia.org/wiki/Venkataraman%20Thangadurai | Venkataraman Thangadurai is a scientist recognized for his work in solid state ionics and chemistry. He is a professor at the University of St Andrews, specializing in Chemistry.
Early life and education
Thangadurai, who was born in India, earned his Chemistry degrees from various institutions in Tamil Nadu and a Ph.D. from the Indian Institute of Science in 1999. He pursued postdoctoral studies in Germany, receiving a fellowship from the Alexander von Humboldt Foundation and a Habilitation degree in 2004 from the University of Kiel.
Career and research
Thangadurai works on creating new materials for energy storage and conversion, particularly in solid oxide fuel cells, batteries and gas separation membranes. His research focuses on ion transport in solid electrolytes and high-performance materials for energy applications. Thangadurai has done work on advancing Li-based garnets within all-solid-state Lithium metal batteries. Thangadurai co-founded Ion Storage Systems and Superionics Inc. Thangadurai submitted 13 patent applications and has 443 publications He moved to the University of St Andrews in early July 2024.
Awards and recognition
HWK-Fellowship, Hanse-Wissenschaftskolleg, Delmenhorst, Germany (2021)
Research Excellence in Materials Chemistry, Chemical Institute of Canada (2021)
Parex Innovation Fellow, University of Calgary (2020)
Peak Scholar, University of Calgary (2019)
Keith Laidler Award, Canadian Society for Chemistry, The Chemical Institute of Canada (2016)
Outstanding Invention of 2013, University of Maryland College Park, USA (2013)
German Academic Exchange Service (DAAD) Guest Professor, Faculty of Engineering, University of Kiel, Germany (2005)
Alexander von Humboldt (AvH) PDF scholarship, Chair for Sensors and Solid-State Ionics, Faculty of Engineering, University of Kiel, Germany (2002)
Selected publications
S. Sarkar, B. Chen, C. Zhou, S.N. Shirazi, F. Langer, J. Schwenzel, and V. Thangadurai,* “Synergistic Approach toward Developing Highly Compatible Garnet-Liquid Electrolyte Interphase in Hybrid Solid-State Lithium-Metal Batteries,” Adv. Energy Mater., 13 (8), 2203897 (14 pages) (2023) (cover page)
T. Boteju, A. M. Abraham, S. Ponnurangam* and V. Thangadurai,* “Theoretical Study on the Role of Solvents in Lithium Polysulfide Anchoring on Vanadium Disulfide Facets for Lithium-Sulfur Batteries,” J. J. Phys. Chem. C. 127 (9), 4416 – 4424 (2023).
A. Sivakumaran, A.J. Samson, and. V. Thangadurai,* “Progress in Sodium Silicates for All-Solid-State Sodium Batteries — a Review,” Energy Technol. 11, 2201323 (18 pages) (2023).
A. M. Abraham, T. Boteju, S. Ponnurangam* and V. Thangadurai,* “A Global Design Principle for Polysulfide Electrocatalysis in Lithium-Sulfur Batteries – A Computational Perspective,” Battery Energy, 20220003 (11 pages), (2022).
V. Thangadurai,* and B. Chen, “Solid Li- and Na-Ion Electrolytes for Next Generation Rechargeable Batteries,” Chem. Mater., 34, 6637–6658 (2022) (Invited John Goodenough at 100 issue).
A. Ndubuisi, S. Abouali, K. Singh, V. Thangadurai,* “Recent Advances, Practical Challenges and Perspectives of Intermediate Temperature Solid Oxide Fuel Cell Cathodes,” J. Mater. Chem. A, 10, 2196-2227 (2022) (Invited).
References
Living people
Year of birth missing (living people)
Indian emigrants to Canada
Solid state chemists
Canadian chemists
21st-century Indian chemists
People from Tamil Nadu
Academic staff of the University of Calgary
Fellows of the Royal Society of Canada
Indian Institute of Science alumni
University of Kiel alumni | Venkataraman Thangadurai | [
"Chemistry"
] | 886 | [
"Solid state chemists"
] |
75,298,411 | https://en.wikipedia.org/wiki/Bluetooth%20Low%20Energy%20denial%20of%20service%20attacks | The Bluetooth Low Energy denial of service attacks are a series of denial-of-service attacks against mobile phones and iPads via Bluetooth Low Energy that can make it difficult to use them.
iPhone and iPad attacks
DEFCON proof of concept attack
At DEF CON 31 in 2023, a demonstration was given using equipment made with a Raspberry Pi, a Bluetooth adapter and a couple of antennas. This attack used Bluetooth advertising packets, hence did not require pairing. The demonstration version claimed to be an Apple TV and affected iOS 16.
Flipper Zero attack
This attack also uses Bluetooth advertising packets to repeatedly send notification signals to iPhones and iPads running iOS 17. It uses a Flipper Zero running third-party Xtreme firmware. It functions even when the device is in airplane mode, and can only be avoided by disabling Bluetooth from the device's Settings app.
The attack can cause the device to crash. It also affects iOS 17.1.
The release of iOS 17.2 made devices more resistant to the attack, reducing the flood of popup messages.
An app to perform these attacks was written for Android.
Interference with a medical device
An attendee of Midwest FurFest 2023 tweeted that the Android device they used to control their insulin pump had been crashed by a BLE attack and that if they hadn't been able to fix it they would have had to go to a hospital.
Wall of Flippers
The Wall of Flippers project has written a Python script that can scan for BTLE attacks. It can run on Linux or Microsoft Windows.
Android attack
The Flipper Zero version of the attack has been adapted to attack Android and Microsoft Windows systems.
References
Bluetooth
Denial-of-service attacks
Hacking in the 2020s | Bluetooth Low Energy denial of service attacks | [
"Technology"
] | 361 | [
"Wireless networking",
"Computer security exploits",
"Denial-of-service attacks",
"Bluetooth"
] |
75,301,583 | https://en.wikipedia.org/wiki/Maisie%27s%20Galaxy | Maisie's Galaxy (also known as CEERS J141946.36+525632.8) is a distant galaxy located at z=11.4 that existed 390 million years after the beginning of the universe.
Background
Discovered in 2022 using the James Webb Space Telescope (JWST) in the CEERS field, Maisie's Galaxy has high star formation rates. It was named after the nine-year-old daughter of the person who discovered it.
In February 2023, the CEERS teams followed up their high-redshift candidates with observatory's NIRSpec (Near-Infrared Spectrograph) instrument to measure precise, spectroscopic redshifts. One candidate (Maisie's Galaxy) has been confirmed to be at redshift 11.4 (when the universe was 390 million years old), while the second candidate was discovered to actually be at a lower redshift of 4.9 (when the universe was 1.2 billion years old).
See also
List of the most distant astronomical objects
References
Galaxies discovered in 2022
Boötes
Galaxies
Discoveries by the James Webb Space Telescope | Maisie's Galaxy | [
"Astronomy"
] | 236 | [
"Galaxy stubs",
"Astronomy stubs",
"Constellations",
"Boötes"
] |
66,589,098 | https://en.wikipedia.org/wiki/WR%20133 | WR 133 is a visually moderately bright Wolf-Rayet star. It is a spectroscopic binary system containing a Wolf-Rayet primary and a class O supergiant secondary. It is in the constellation of Cygnus, lying in the sky at the centre of the triangle formed by β and γ Cygni, near η Cygni. It is the brightest member of the sparse open cluster NGC 6871.
WR 133 is one of the brightest Wolf Rayet (WR) stars in the northern hemisphere, slightly brighter than WR 140 which also in Cygnus. The WR star is typically identified as the primary, being more luminous, and dominating the spectrum. However, the supergiant secondary is more massive and visually brighter. The primary star is a WN5 nitrogen-rich WR star and the secondary has a spectral type of O9I. The orbit is moderately eccentric and has a period of , which has been determined from the velocity variations observed with the component's spectral lines, mostly from the He emission lines at for the WR primary, and helium and oxygen absorption lines for the primary. This is the first WN-type WR star to have its mass dynamically determined from orbital motion, although the precision is hampered by the nearly face-on orientation of the orbit.
WR 133 is listed as a Wolf-Rayet variable star and has been given the variable star designation V1676 Cyg in the General Catalogue of Variable Stars. Its visual magnitude varies between 6.75 and 6.84.
References
Cygnus (constellation)
Wolf–Rayet stars
J20055731+3547181
190918
Spectroscopic binaries
Cygni, V1676
BD+35 3953
099002
O-type supergiants | WR 133 | [
"Astronomy"
] | 362 | [
"Cygnus (constellation)",
"Constellations"
] |
66,589,724 | https://en.wikipedia.org/wiki/Cortinarius%20sulfurinus | Cortinarius sulfurinus is a species of fungus belonging to the family Cortinariaceae.
Synonym:
Cortinarius sulfurinus var. sulfurinus Quél., 1884
References
Cortinariaceae
Fungus species | Cortinarius sulfurinus | [
"Biology"
] | 46 | [
"Fungi",
"Fungus species"
] |
66,589,950 | https://en.wikipedia.org/wiki/Aimsun | Aimsun (short for "Advanced Interactive Microscopic Simulator for Urban and Non-Urban Networks") is a software company that provides simulation software and services for transportation planning and traffic management.
Overview
Aimsun was founded in 1997 and developed Aimsun Next traffic modeling software, which simulates mobility in networks.
Aimsun also develops Aimsun Live, which is a simulation-based traffic forecasting software as well as Aimsun Auto for studying path planning in driverless vehicles, and Aimsun Ride for modeling demand-responsive transportation services.
Aimsun was acquired by Siemens in 2018 for an undisclosed sum, as part of the Siemens Mobility Intelligent Traffic Systems (ITS) unit.
In 2021, Siemens Mobility carved out the Intelligent Traffic Systems (ITS) unit, of which Aimsun is a part, and renamed it Yunex Traffic.
In 2022, Italian infrastructure group Mundys (then known as Atlantia) bought Siemens' Yunex Traffic division for 950 million euros ($1.1 billion) to expand its transport services, making Aimsun a part of the Mundys group.
Transport models
Paris (Aimsun Paris match)
London (Transport for London, Aimsun Next platform)
Sydney
New York City
Abu Dhabi (Aimsun Abu Dhabi transport model)
Singapore (Aimsun Live Technology Trial in Singapore)
Bergen (Aimsun smart traffic management pilot in Norway)
Western Australia (Transport predictive solution)
Recognition
Highways Industry category award for Aimsun’s air quality modelling solution at the Highways Awards.
Smart Transport Infrastructure Award (M4 Smart Motorway Project – Simulation-Based Support for Smart Motorway Infrastructure)
Won Excellence in Research and Development Award by ITS for Sydney Victoria Road Intelligent Decision Support System
References
Simulation software
Traffic management | Aimsun | [
"Engineering"
] | 342 | [
"Systems engineering",
"Traffic management"
] |
66,590,304 | https://en.wikipedia.org/wiki/Su%E2%80%93Schrieffer%E2%80%93Heeger%20model | In condensed matter physics, the Su–Schrieffer–Heeger (SSH) model or SSH chain is a one-dimensional lattice model that presents topological features. It was devised by Wu-Pei Su, John Robert Schrieffer, and Alan J. Heeger in 1979, to describe the increase of electrical conductivity of polyacetylene polymer chain when doped, based on the existence of solitonic defects. It is a quantum mechanical tight binding approach, that describes the hopping of spinless electrons in a chain with two alternating types of bonds. Electrons in a given site can only hop to adjacent sites.
Depending on the ratio between the hopping energies of the two possible bonds, the system can be either in metallic phase (conductive) or in an insulating phase. The finite SSH chain can behave as a topological insulator, depending on the boundary conditions at the edges of the chain. For the finite chain, there exists an insulating phase, that is topologically non-trivial and allows for the existence of edge states that are localized at the boundaries.
Description
The model describes a half-filled one-dimensional lattice, with two sites per unit cell, A and B, which correspond to a single electron per unit cell. In this configuration each electron can either hop inside the unit cell or hop to an adjacent cell through nearest neighbor sites. As with any 1D model, with two sites per cell, there will be two bands in the dispersion relation (usually called optical and acoustic bands). If the bands do not touch, there is a band gap. If the gap lies at the Fermi level, then the system is considered to be an insulator.
The tight binding Hamiltonian in a chain with N sites can be written as
where h.c. denotes the Hermitian conjugate, v is the energy required to hop from a site A to B inside the unit cell, and w is the energy required to hop between unit cells. Here the Fermi energy is fixed to zero.
Bulk solution
The dispersion relation for the bulk can be obtained through a Fourier transform. Taking periodic boundary conditions , where , we pass to k-space by doing
,
which results in the following Hamiltonian
where the eigenenergies are easily calculated as
and the corresponding eigenstates are
where
The eigenenergies are symmetrical under swap of , and the dispersion relation is mostly gapped (insulator) except when (metal). By analyzing the energies, the problem is apparently symmetric about , the has the same dispersion as . Nevertheless, not all properties of the system are symmetrical, for example the eigenvectors are very different under swap of . It can be shown for example that the Berry connection
integrated over the Brillouin zone , produces different winding numbers:
showing that the two insulating phases, and , are topologically different (small changes in v and w change but not over the Brillouin zone). The winding number remains undefined for the metallic case . This difference in topology means that one cannot pass from an insulating phase to another without closing the gap (passing by the metallic phase). This phenomenon is called a topological phase transition.
Finite chain solution and edge states
The physical consequences of having different winding number become more apparent for a finite chain with an even number of lattice sites. It is much harder to diagonalize the Hamiltonian analytically in the finite case due to the lack of translational symmetry.
Dimerized cases
There exist two limiting cases for the finite chain, either or . In both of these cases, the chain is clearly an insulator as the chain is broken into dimers (dimerized). However one of the two cases would consist of dimers, while the other case would consist of dimers and two unpaired sites at the edges of the chain. In the latter case, as there is no on-site energy, if an electron finds itself on any of the two edge sites, its energy would be zero. So either the case or the case would necessarily have two eigenstates with zero energy, while the other case would not have zero-energy eigenstates. Contrary to the bulk case, the two limiting cases are not symmetrical in their spectrum.
Intermediate values
By plotting the eigenstates of the finite chain as function of position, one can show that there are two distinct kinds of states. For non-zero eigenenergies, the corresponding wavefunctions would be delocalized all along the chain while the zero energy eigenstates would portray localized amplitudes at the edge sites. The latter are called edge states. Even if the eigenenergies lie in the gap, the edge states are localized and correspond to an insulating phase.
By plotting the spectrum as a function of for a fixed value of , the spectrum is divided into two insulating regions divided by the metallic intersection at . The spectrum would be gapped in both insulating regions, but one of the regions would show zero energy eigenstates and the other region would not, corresponding to the dimerized cases. The existence of edge states in one region and not in the other demonstrate the difference between insulating phases and it is this sharp transition at that correspond to a topological phase transition.
Correspondence between finite and bulk solutions
The bulk case allows to predict which insulating region would present edge states, depending on the value of the winding number in the bulk case. For the region where the winding number is in the bulk, the corresponding finite chain with an even number of sites would present edge states, while for the region where the winding number is in the bulk case, the corresponding finite chain would not. This relation between winding numbers in the bulk and edge states in the finite chain is called the bulk-edge correspondence.
See also
Kitaev chain
Peierls transition
References
Condensed matter physics | Su–Schrieffer–Heeger model | [
"Physics",
"Chemistry",
"Materials_science",
"Engineering"
] | 1,196 | [
"Phases of matter",
"Condensed matter physics",
"Matter",
"Materials science"
] |
66,592,277 | https://en.wikipedia.org/wiki/Pesticide%20refuge%20area | A refuge area is a countermeasure against pesticide resistance in agriculture. In this technique two adjacent pieces of land are demarcated, and one is applied with a pesticide and one is not - the refuge. Given that resistance develops concurrent with application, a more complex way of dealing with the problem is needed than simply using or not using a particular pesticide. A refuge encourages the overall population to maintain a lower prevalence of resistance by segmenting them into two populations: The population receiving the pesticide and the pesticide-free population. Over time the population that suffers pesticide application will evolve resistance - and more widespread resistance. Meanwhile, the other will continue to be pesticide-naive. However the trick here is that a larger proportion of the main population will die off - allowing the pesticide-naive genetics to more successfully reproduce within the overall area, and thus to dominate the overall population.
Refugia are commonly used today especially to maintain effectiveness in Bt-modified transgenic crops.
References
Environmental effects of pesticides
Pesticides
Crop protection
Insect ecology
Population ecology
Agricultural pests
Ecological genetics
Biological evolution | Pesticide refuge area | [
"Biology",
"Environmental_science"
] | 224 | [
"Toxicology",
"Pesticides",
"Biocides",
"Pests (organism)",
"Agricultural pests"
] |
66,597,501 | https://en.wikipedia.org/wiki/Finnlakeviridae | Finnlakeviridae is a family of bacterial viruses that is not assigned to any higher taxonomic ranks. The family contains a single genus, Finnlakevirus, which contains a single species, Flavobacterium virus FLiP. This virus was isolated in 2010, with its gram-negative host Flavobacterium, from Lake Jyväsjärvi, a boreal freshwater habitat in Central Finland, and is the first described single-stranded DNA virus with an internal membrane.
The genome is circular single-stranded DNA of about 9200 nucleotides in length.
References
External links
ICTV Report: Finnlakeviridae
PNAS Paper: Finnlakeviridae
Virus families | Finnlakeviridae | [
"Biology"
] | 140 | [
"Virus stubs",
"Viruses"
] |
66,597,898 | https://en.wikipedia.org/wiki/Ovaliviridae | Ovaliviridae is a family of viruses of archaea that is not assigned to any higher taxonomic ranks. The family contains a single genus, Alphaovalivirus, which contains a single species, Sulfolobus ellipsoid virus 1. The linear genome of dsDNA is 23,219 bp with 172 bp inverted terminal repeats. Sulfolobus ellipsoid virus 1 was isolated from an acidic hot spring (86−106oC, pH 2.2−2.5) in Laguna Fumarólica, Costa Rica; the only known host is Sulfolobus sp. A20.
References
External links
ICTV Report: Ovaliviridae
Virus families | Ovaliviridae | [
"Biology"
] | 141 | [
"Virus stubs",
"Viruses"
] |
66,598,289 | https://en.wikipedia.org/wiki/Tolecusatellitidae | Tolecusatellitidae is a incertae sedis ssDNA/ssDNA(+) family of biological satellites. The family contains two genera and 131 species. This family of viruses depend on the presence of another virus (helper viruses) to replicate their genomes, as such they have minimal genomes with very low genomic redundancy.
Name
The name Tolecusatellitidae is a combination of Tolecu, from the first DNA satellite shown to be associated with Tomato leaf curl virus and satellite, the fact that it is a satellite.
Taxonomy
The species are ssDNA unless specified ssDNA(+). There are 62 ssDNA(+) and 69 ssDNA satellites.
Betasatellite
Ageratum leaf curl Buea betasatellite
Ageratum leaf curl Cameroon betasatellite
Ageratum yellow leaf curl betasatellite
Ageratum yellow vein betasatellite
Ageratum yellow vein China betasatellite ssDNA(+)
Ageratum yellow vein Sri Lanka betasatellite
Alternanthera yellow vein betasatellite
Andrographis yellow vein leaf curl betasatellite
Bhendi yellow vein mosaic betasatellite
Cardiospermum yellow leaf curl betasatellite
Chili leaf curl betasatellite
Chili leaf curl Jaunpur betasatellite
Chili leaf curl Sri Lanka betasatellite
Codiaeum leaf curl betasatellite ssDNA(+)
Cotton leaf curl Bahraich betasatellite ssDNA(+)
Cotton leaf curl Bangalore betasatellite 1 ssDNA(+)
Cotton leaf curl Bangalore betasatellite 2 ssDNA(+)
Cotton leaf curl Bangalore betasatellite 3 ssDNA(+)
Cotton leaf curl Bangalore betasatellite 4 ssDNA(+)
Cotton leaf curl Burkina Faso betasatellite ssDNA(+)
Cotton leaf curl Gezira betasatellite
Cotton leaf curl Kashmir betasatellite ssDNA(+)
Cotton leaf curl Multan betasatellite
Cotton leaf curl Tandojam betasatellite ssDNA(+)
Croton yellow vein mosaic betasatellite
Emilia yellow vein betasatellite ssDNA(+)
Emilia yellow vein Fujian betasatellite ssDNA(+)
Erectites yellow mosaic betasatellite ssDNA(+)
Eupatorium yellow vein betasatellite
Eupatorium yellow vein mosaic betasatellite
French bean leaf curl betasatellite
Hedyotis yellow mosaic betasatellite
Hibiscus vein enation betasatellite ssDNA(+)
Honeysuckle yellow vein betasatellite
Honeysuckle yellow vein mosaic betasatellite
Honeysuckle yellow vein mosaic Ibaraki betasatellite ssDNA(+)
Honeysuckle yellow vein mosaic Nara betasatellite ssDNA(+)
Kenaf leaf curl betasatellite ssDNA(+)
Leucas zeylanica yellow vein betasatellite ssDNA(+)
Lindernia anagallis yellow vein betasatellite ssDNA(+)
Ludwigia leaf distortion betasatellite 1 ssDNA(+)
Ludwigia leaf distortion betasatellite 2 ssDNA(+)
Ludwigia leaf distortion betasatellite 3 ssDNA(+)
Ludwigia yellow vein betasatellite ssDNA(+)
Malvastrum leaf curl betasatellite ssDNA(+)
Malvastrum yellow vein betasatellite ssDNA(+)
Malvastrum yellow vein Cambodia betasatellite ssDNA(+)
Malvastrum yellow vein Yunnan betasatellite 1 ssDNA(+)
Malvastrum yellow vein Yunnan betasatellite 2 ssDNA(+)
Mirabilis leaf curl betasatellite
Momordica yellow mosaic betasatellite
Mungbean yellow mosaic betasatellite
Okra leaf curl betasatellite ssDNA(+)
Okra leaf curl Oman betasatellite
Papaya leaf curl betasatellite
Papaya leaf curl China betasatellite
Papaya leaf curl Gandhinagar betasatellite ssDNA(+)
Papaya leaf curl India betasatellite
Papaya leaf curl India betasatellite 2 ssDNA(+)
Pea leaf distortion betasatellite ssDNA(+)
Radish leaf curl betasatellite ssDNA(+)
Rhynchosia yellow mosaic betasatellite
Rose leaf curl betasatellite
Sida leaf curl betasatellite ssDNA(+)
Sida yellow mosaic betasatellite ssDNA(+)
Sida yellow vein Barrackpore betasatellite ssDNA(+)
Sida yellow vein Madurai betasatellite ssDNA(+)
Sida yellow vein Vietnam betasatellite 1 ssDNA(+)
Sida yellow vein Vietnam betasatellite 2 ssDNA(+)
Siegesbeckia yellow vein betasatellite
Siegesbeckia yellow vein betasatellite 2 ssDNA(+)
Siegesbeckia yellow vein Guangxi betasatellite ssDNA(+)
Tobacco curly shoot betasatellite
Tobacco leaf chlorosis betasatellite ssDNA(+)
Tobacco leaf curl betasatellite
Tobacco leaf curl Japan betasatellite
Tobacco leaf curl Patna betasatellite
Tobacco leaf curl Sheikhupura betasatellite ssDNA(+)
Tobacco leaf curl Yunnan betasatellite ssDNA(+)
Tomato leaf curl Bangalore betasatellite
Tomato leaf curl Bangalore betasatellite 2 ssDNA(+)
Tomato leaf curl Bangladesh betasatellite
Tomato leaf curl betasatellite ssDNA(+)
Tomato leaf curl betasatellite 2 ssDNA(+)
Tomato leaf curl Bundi betasatellite
Tomato leaf curl China betasatellite
Tomato leaf curl Gandhinagar betasatellite
Tomato leaf curl Ghana betasatellite 1 ssDNA(+)
Tomato leaf curl Ghana betasatellite 2 ssDNA(+)
Tomato leaf curl Hajipur betasatellite ssDNA(+)
Tomato leaf curl India betasatellite ssDNA(+)
Tomato leaf curl Java betasatellite
Tomato leaf curl Joydebpur betasatellite
Tomato leaf curl Joydebpur betasatellite 2 ssDNA(+)
Tomato leaf curl Karnataka betasatellite ssDNA(+)
Tomato leaf curl Laguna betasatellite
Tomato leaf curl Laos betasatellite
Tomato leaf curl Lucknow betasatellite ssDNA(+)
Tomato leaf curl Malaysia betasatellite
Tomato leaf curl Nepal betasatellite
Tomato leaf curl Pakistan betasatellite ssDNA(+)
Tomato leaf curl Panipat betasatellite ssDNA(+)
Tomato leaf curl Patna betasatellite
Tomato leaf curl Philippine betasatellite
Tomato leaf curl Pune betasatellite ssDNA(+)
Tomato leaf curl Ranchi betasatellite ssDNA(+)
Tomato leaf curl Sri Lanka betasatellite
Tomato leaf curl Togo betasatellite ssDNA(+)
Tomato leaf curl Yemen betasatellite
Tomato yellow dwarf betasatellite ssDNA(+)
Tomato yellow leaf curl China betasatellite
Tomato yellow leaf curl Shandong betasatellite
Tomato yellow leaf curl Thailand betasatellite
Tomato yellow leaf curl Vietnam betasatellite
Tomato yellow leaf curl Yunnan betasatellite
Vernonia crinkle betasatellite ssDNA(+)
Vernonia yellow vein betasatellite
Vernonia yellow vein Fujian betasatellite
Zinnia leaf curl betasatellite ssDNA(+)
Deltasatellite
Croton yellow vein deltasatellite
Desmodium leaf distortion deltasatellite ssDNA(+)
Malvastrum leaf curl deltasatellite
Sida golden yellow vein deltasatellite 1
Sida golden yellow vein deltasatellite 2
Sida golden yellow vein deltasatellite 3
sweet potato leaf curl deltasatellite 1
sweet potato leaf curl deltasatellite 2
sweet potato leaf curl deltasatellite 3
tomato leaf curl deltasatellite
tomato yellow leaf distortion deltasatellite 1
tomato yellow leaf distortion deltasatellite 2
References
Virus families | Tolecusatellitidae | [
"Biology"
] | 1,666 | [
"Virus stubs",
"Viruses"
] |
66,598,855 | https://en.wikipedia.org/wiki/Thank%20you | "Thank you" (often expanded to thank you very much or thanks a lot, or informally abbreviated to thanks or alternately as many thanks) is a common expression of gratitude in the English language. The term itself originated as a shortened form of the expression "I thank you". Children in certain Western cultures are taught early on to say please and thank you reflexively, and the phrase itself has taken on a variety of nuances based on intonation, and can have various generally positive social effects.
Learning to use the term
Use of the phrase indicates politeness, and in certain Western cultures, "parents put a lot of effort into teaching their children to be polite, to say 'thank you' or 'please' for every single favor done by anyone", though the practice of quizzing children on what they should say has been criticized as framing the question in a negative context of the child being forgetful, and that the parent should merely remind the child to "Say please and thank you". It has generally been observed that "parents train their kids to say 'thank you' whether they feel thankful or not", and has specifically been noted that withholding food from children in order to elicit politeness "may teach children that the words 'please' and 'thank you' are tokens they must use to get their food rather than genuine expressions of gratitude".
Social function
Philosopher David J. Gunkel notes that "[i]t is now common for users to say 'thank you' to their digital assistants and speech dialogue systems (SDS), like Amazon's Echo/Alexa, Google Home, and Apple's Siri". Gunkel notes that this may appear to be superfluous, since the statement neither offers information to the system for processing, nor is capable of being processed by the system and understood as a command, but concludes that it is nevertheless socially important because it recognizes the system as fulfilling a social function.
Use of the phrase by teachers has been observed to elicit better responses in the teaching of children:
In other environs, one study found that regular patrons of a restaurant gave bigger tips when servers wrote "Thank you" on their checks.
As with various other formal phrases, the phrase "Thank you" can be varied in speaking so as to convey many different meanings. For example, "no, thank you" or "no thanks" are often used to indicate politeness while declining an offer. It can also be incorporated into phrases sarcastically or bitterly, as with the phrase, "thanks for nothing". Common responses for "thank you" include "you're welcome", "don't mention it", or, more recently, according to a 2018 HuffPost article, "no problem".
Cultural variations
A wide variety of verbal cues for the expression of gratitude exist in different languages. A 2012 Vanity Fair poll indicated that "thank you" was the phrase American travelers abroad, especially in east Asian Nations, felt was most important to learn how to say in the language of the country being visited.
It has been observed that in some versions of African English (specifically in Kenyan English), "thank you" is often used as a traditional response to a departing person saying "goodbye".
See also
Deo gratias, Latin phrase meaning "thanks [be] to God"
God bless you
References
External links
English phrases
Etiquette
Magic words | Thank you | [
"Biology"
] | 690 | [
"Etiquette",
"Behavior",
"Human behavior"
] |
66,598,890 | https://en.wikipedia.org/wiki/Twitter%20verification | Twitter verification is a system intended to communicate the authenticity of a Twitter account. Since November 2022, Twitter users whose accounts are at least 90 days old and have a verified phone number receive verification upon subscribing to X Premium or Verified Organizations; this status persists as long as the subscription remains active.
When introduced in June 2009, the system provided the site's readers with a means to distinguish genuine notable account holders, such as celebrities and organizations, from impostors or parodies. Until November 2022, a blue checkmark displayed against an account name indicated that Twitter had taken steps to ensure that the account was actually owned by the person or organization whom it claimed to represent. The checkmark does not imply endorsement from Twitter, and does not mean that tweets from a verified account are necessarily accurate or truthful in any way. People with verified accounts on Twitter are often colloquially referred to as "blue checks" on social media and by reporters.
In November 2022, the verification program was modified heavily by new owner Elon Musk, extending verification to any account with a verified phone number and an active subscription to an eligible X Premium (formerly Twitter Blue) plan. These changes faced criticism from users and the media, who believed that the changes would ease impersonation, and allow accounts spreading misleading information to feign credibility. In a related change, Twitter introduced additional gold and gray checkmarks, used by Verified Organizations and government-affiliated accounts, respectively. Twitter claims that the changes to verification are required to "reduce fraudulent accounts and bots".
Twitter users who had been verified through the previous system were known as "legacy verified" accounts; legacy verification was deprecated in April 2023, and stripped from accounts who do not meet the new payment requirements. Musk later implied that he had been personally paying for the X Premium subscriptions of several notable celebrities.
History
2009–2022
In June 2009, after being criticized by Kanye West and sued by Tony La Russa over unauthorized accounts run by impersonators, the company launched their "Verified Accounts" program. Twitter stated that an account with a "blue tick" verification badge indicates "we've been in contact with the person or entity the account is representing and verified that it is approved". After the beta period, the company stated in their FAQ that it "proactively verifies accounts on an ongoing basis to make it easier for users to find who they're looking for" and that they "do not accept requests for verification from the general public".
Originally, Twitter took on the responsibility of reaching out to celebrities and other notable people to confirm their identities in order to establish a verified account.
In July 2016, Twitter announced a public application process to grant verified status to an account "if it is determined to be of public interest" and that verification "does not imply an endorsement". In 2016, the company began accepting requests for verification, but it was discontinued the same year. Twitter explained that the volume of requests for verified accounts had exceeded its ability to cope; rather, Twitter determines on its own whom to approach about verified accounts, limiting verification to accounts which are "authentic, notable, and active".
In November 2020, Twitter announced a relaunch of its verification system in 2021. According to the new policy, Twitter verifies six different types of accounts; for three of them (companies, brands, and influential individuals like activists), the existence of a Wikipedia page will be one criterion for showing that the account has "Off Twitter Notability".
Controversy
On June 21, 2014, actor William Shatner raised an issue with several Engadget editorial staff and their verification status on Twitter. Besides the site's social media editor, John Colucci, Shatner also targeted several junior members of the staff for being "nobodies", unlike some of his actor colleagues who did not bear such distinction. Shatner claimed Colucci and the team were bullying him when giving a text interview to Mashable. Over a month later, Shatner continued to discuss the issue on his Tumblr page, to which Engadget replied by defending its team and discussing the controversy surrounding the social media verification.
Twitter's practice and process for verifying accounts came under scrutiny again in 2017 after the company verified the account of white supremacist and far-right political activist, Jason Kessler. Many who criticized Twitter's decision to verify Kessler's account saw this as a political act on the company's behalf. In response, Twitter put its verification process on hold. The company tweeted, "Verification was meant to authenticate identity & voice but it is interpreted as an endorsement or an indicator of importance. We recognize that we have created this confusion and need to resolve it. We have paused all general verifications while we work and will report back soon."
As of November 2017, Twitter continued to deny verification of Julian Assange's account following his requests.
In November 2019, Dalit activists of India alleged that higher-caste people get Twitter verification easily and trended hashtags #CancelAllBlueTicksInIndia and #CasteistTwitter. Critics have said that the company's verification process is not transparent and causes digital marginalisation of already marginalised communities. Twitter India rejected the allegations, calling them "impartial" and working on a "" policy.
Since November 2022
Following the acquisition of Twitter by Elon Musk on October 28, 2022, Musk told Twitter employees to introduce paid verification by November 7 through Twitter Blue. The Verge reported that the updated Blue subscription would cost $19.99 per month, and users would lose their verification status if they did not join within 90 days. Following backlash, Musk tweeted, in response to author Stephen King, a lowered $8 price on . Twitter confirmed the new price of $7.99 per month on November 5, 2022. The new verification system began rollout on , a day after the 2022 United States elections. The decision to delay its rollout was to address concerns about users potentially spreading misinformation about voting results by posing as news outlets and lawmakers.
At the same time, Twitter introduced a secondary gray "Official" label on some high-profile accounts, but removed them hours after launch. Less than 48 hours later, Twitter reinstated the gray "Official" label, after multiple users were suspended for deliberately impersonating reporters and high-profile athletes like LeBron James. A viral tweet from an account purporting to be the pharmaceutical company Eli Lilly and Company caused the company's stock to fall after announcing "insulin is free now". As a result, Twitter disabled new Blue subscriptions on .
On December 12, 2022, Twitter Blue was relaunched again with some changes, including an increased price of $11 for users who sign up through iOS devices to compensate for the 30% cut imposed by Apple. Twitter stated that only Twitter accounts older than 90days and with a confirmed phone number are able to subscribe and Blue checkmarks are issued once Twitter reviews the account, and any changes to the profile "will result in the loss of the blue checkmark" until Twitter can review the account again. The "Official" labels were replaced with Verified Organizations, which are displayed with a gold checkmark and square-shaped avatars (as opposed to circular avatars for all other accounts): this program costs $1,000 per-month, with Verified Organizations able to add verification to affiliated accounts for an additional fee of $50 per-month for each account. Gray checkmarks were also added for government accounts on Twitter.
Accounts that had been verified through the previous system were renamed to "legacy verified", with Musk calling the previous system "corrupt and nonsensical" in a tweet, and stating the blue checkmarks on those accounts would be removed "in a few months". Musk claimed that the impersonation issue was resolved by manually reviewing all applications, but The Washington Post tech columnist Geoffrey A. Fowler was able to create an impersonation account of senator Ed Markey, which was promptly verified after subscribing to Twitter Blue and only suspended after Fowler's story was published.
On April 24, 2023, a parody account of the defunct Disney Junior channel in the United Kingdom was verified with a gold checkmark. The account, which tweeted profanities and claimed that South Park and Family Guy would be coming to Disney Junior, became viral and was later suspended.
Removal of legacy verification
On March 23, 2023, Twitter announced that on April 1, 2023, it would begin winding down its legacy verification program and removing legacy verified checkmarks. The New York Times reported that exceptions would be made for Twitter's top 500 advertisers and its 10,000 most-followed organizations that had been previously verified. BuzzFeed News reported that multiple news organizations like The New York Times, The Washington Post and The Los Angeles Times had no plans to pay for Twitter's "Verified Organizations" service nor would they reimburse reporters for having Twitter Blue. Similarly, Axios reported that White House digital strategy director Rob Flaherty sent an internal email to staffers saying "[t]here are ongoing trials for the program that we are monitoring, but we will not enroll in it."
Twitter did not immediately begin removing checkmarks on April 1, 2023. The Washington Post reported that "[the removal] of verification badges is a largely manual process powered by a system prone to breaking" and "[i]n the past, there was no way to reliably remove badges at a bulk scale", according to former Twitter employees. However, on April 2, 2023, the main account for The New York Times became one of the first major media companies to lose its verified status on Twitter. The loss of verification came after Musk replied "Oh ok, we'll take it off then" to a Twitter user who tweeted that The New York Times would not pay for Twitter verification. He criticised the newspaper for tweeting hundreds of posts every day, including drafts that were not accepted into the published editions of the paper, and inundating the daily feed of users who followed it. Despite the deadline for Twitter Blue passing, and aside from The New York Times, many legacy verified accounts continued to retain their verified status. Twitter also updated the language previously used to distinguish between legacy and Twitter Blue-verified users, merging them into a single description, and later unfollowed all legacy-verified accounts. On April 11, 2023, Musk announced the final date for removing legacy blue checkmarks to be April 20.
Despite skepticism due to the chosen date, Twitter began removing legacy checkmarks on April 20, 2023. Among those that lost their verified status included Cristiano Ronaldo and Beyoncé. Following the removal of legacy verification, Twitter began verifying the accounts of several celebrities who had been critical of, and did not purchase Twitter Blue, including Stephen King, LeBron James, Hasan Piker, and dril. Musk implied that he was paying for their subscriptions personally. A day later, Twitter updated its policy for Twitter Ads requiring all advertisers to be subscribed to Verified Organizations, but businesses spending at least $1000 a month in advertising would automatically receive membership in the Verified Organizations program at no additional cost. On April 22, 2023, Twitter seemingly began issuing blue and gold checkmarks to accounts with at least a million followers, including those belonging to deceased users such as Anthony Bourdain, Chadwick Boseman, and Kobe Bryant. Since the blue checkmark now indicates an active Twitter Blue subscription, several highprofile users began looking for ways to remove it, usually by briefly changing their display name.
On April 25, 2023, Musk announced that posts by verified accounts would now be prioritized ahead of unverified users, but behind those of the user's own follows, in replies to tweets.
On April 30, 2023, multiple legacy verified users began noticing a bug that temporarily restored the legacy blue checkmark by changing their bio.
On October 17, 2023, X announced that it would trial a scheme requiring new users who register via the website in New Zealand and the Philippines to pay US$1 per-year in order to use the platform. If the user does not subscribe, they will only receive read-only access to the platform. It was stated that this system was required to "bolster our already significant efforts to reduce spam, manipulation of our platform and bot activity."
Significance and social impact
Prior to the introduction of paid Twitter verification after the acquisition of Twitter by Elon Musk, verified status was a highly sought-after qualification among Twitter users. Since Twitter alone granted blue checkmarks, they could use them as a passive inducement for users to create more content. Alison Hearn argued in 2017 that they introduce a new social class of Twitter users. This can cause tension between verified and non-verified users of the site; when Twitter temporarily locked out verified accounts in the aftermath of the 2020 Twitter account hijacking, many non-verified users celebrated.
After the blue checkmark was made available as a paid subscription in 2022, reporters noted trolls spreading conspiracy theories about COVID-19 vaccines using the checkmark to feign credibility.
Several fake accounts surfaced following Twitter's move to eliminate the blue tick verification on April 20, 2023. An account pretending to be Hillary Clinton "announced" her intention to run for the presidency again. The said fake account used an identical profile photo as that of the former U.S. senator's legitimate handle. Moreover, a new Twitter handle in New York City claimed to be a legitimate account representing the government.
The BBC has noted that the increase in sponsored verification would heighten the spread of false information on the platform.
Notes
References
External links
Twitter Support — About Verified Accounts
Twitter Support — Verification FAQ
Twitter
Social media
Identity management
Computer access control
Internet culture | Twitter verification | [
"Technology",
"Engineering"
] | 2,873 | [
"Cybersecurity engineering",
"Computing and society",
"Computer access control",
"Social media"
] |
66,599,131 | https://en.wikipedia.org/wiki/Gliese%20328 | Gliese 328, also known as BD+02 2098, is a M-type main-sequence star located away in the constellation Hydra. Its surface temperature is 3989 K. Gliese 328 is depleted in heavy elements compared to the Sun, with a metallicity Fe/H index of −0.13. The age of the star is unknown. Gliese 328 exhibits an activity cycle similar to that of the Sun, with a period around 2000 d.
Multiplicity surveys did not detect any stellar companions as of 2016.
Planetary system
In 2013, one superjovian planet, named Gliese 328 b, was discovered on a wide, eccentric orbit by the radial velocity method. The known planetary orbit is wide enough to not disrupt orbits of other bodies in the habitable zone of the star. In 2023, a second, Neptune-mass planet was discovered orbiting closer to the star.
References
Hydra (constellation)
M-type main-sequence stars
Planetary systems with two confirmed planets
J08550761+0132472
BD+02 2098
043790
0328 | Gliese 328 | [
"Astronomy"
] | 228 | [
"Hydra (constellation)",
"Constellations"
] |
66,599,603 | https://en.wikipedia.org/wiki/Laurilia%20sulcata | Laurilia sulcata is a species of fungus belonging to the family Echinodontiaceae.
It is native to Eurasia and Northern America.
References
Russulales
Fungus species | Laurilia sulcata | [
"Biology"
] | 39 | [
"Fungus stubs",
"Fungi",
"Fungus species"
] |
66,600,012 | https://en.wikipedia.org/wiki/Quantum%20engineering | Quantum engineering is the development of technology that capitalizes on the laws of quantum mechanics. This type of engineering uses quantum mechanics to develop technologies such as quantum sensors and quantum computers.
Devices that rely on quantum mechanical effects such as lasers, MRI imagers and transistors have revolutionized many areas of technology. New technologies are being developed that rely on phenomena such as quantum coherence and on progress achieved in the last century in understanding and controlling atomic-scale systems. Quantum mechanical effects are used as a resource in novel technologies with far-reaching applications, including quantum sensors and novel imaging techniques, secure communication (quantum internet) and quantum computing.
History
The field of quantum technology was explored in a 1997 book by Gerard J. Milburn. It was then followed by a 2003 article by Milburn and Jonathan P. Dowling, and a separate publication by David Deutsch on the same year.
The application of quantum mechanics was evident in several technologies. These include laser systems, transistors and semiconductor devices, as well as other devices such as MRI imagers. The UK Defence Science and Technology Laboratory (DSTL) grouped these devices as 'quantum 1.0' to differentiate them from what it dubbed as 'quantum 2.0'. This is a definition of the class of devices that actively create, manipulate, and read out quantum states of matter using the effects of superposition and entanglement.
From 2010 onwards, multiple governments have established programmes to explore quantum technologies, such as the UK National Quantum Technologies Programme, which created four quantum 'hubs'. These hubs are found at the Centre for Quantum Technologies in Singapore, and QuTech, a Dutch center to develop a topological quantum computer. In 2016, the European Union introduced the Quantum Technology Flagship, a €1 Billion, 10-year-long megaproject, similar in size to earlier European Future and Emerging Technologies Flagship projects.
In December 2018, the United States passed the National Quantum Initiative Act, which provides a US$1 billion annual budget for quantum research. China is building the world's largest quantum research facility with a planned investment of 76 billion Yuan (approx. €10 Billion). Indian government has also invested 8000 crore Rupees (approx. US$1.02 Billion) over 5-years to boost quantum technologies under its National Quantum Mission.
In the private sector, large companies have made multiple investments in quantum technologies. Organizations such as Google, D-wave systems, and University of California Santa Barbara have formed partnerships and investments to develop quantum technology.
Applications
Secure communications
Quantum secure communication is a method that is expected to be 'quantum safe' in the advent of quantum computing systems that could break current cryptography systems using methods such as Shor's algorithm. These methods include quantum key distribution (QKD), a method of transmitting information using entangled light in a way that makes any interception of the transmission obvious to the user. Another method is the quantum random number generator, which is capable of producing truly random numbers unlike non-quantum algorithms that merely imitate randomness.
Computing
Quantum computers are expected to have a number of important uses in computing fields such as optimization and machine learning. They are perhaps best known for their expected ability to carry out Shor's algorithm, which can be used to factorize large numbers and is an important process in the securing of data transmissions.
Quantum simulators are types of quantum computers intended to simulate a real world system, such as a chemical compound. Quantum simulators are simpler to build as opposed to general purpose quantum computers because complete control over every component is not necessary. Current quantum simulators under development include ultracold atoms in optical lattices, trapped ions, arrays of superconducting qubits, and others.
Sensors
Quantum sensors are expected to have a number of applications in a wide variety of fields including positioning systems, communication technology, electric and magnetic field sensors, gravimetry as well as geophysical areas of research such as civil engineering and seismology.
Education programs
Quantum engineering is evolving into its own engineering discipline. The quantum industry requires a quantum-literate workforce, a missing resource at the moment. Currently, scientists in the field of quantum technology have mostly either a physics or engineering background and have acquired their ”quantum engineering skills” by experience. A survey of more than twenty companies aimed to understand the scientific, technical, and “soft” skills required of new hires into the quantum industry. Results show that companies often look for people that are familiar with quantum technologies and simultaneously possess excellent hands-on lab skills.
Several technical universities have launched education programs in this domain. For example, ETH Zurich has initiated a Master of Science in Quantum Engineering, a joint venture between the electrical engineering department (D-ITET) and the physics department (D-PHYS), EPFL offers a dedicated Master’s program in Quantum Science and Engineering, combining coursework in quantum physics and engineering with research opportunities, and the University of Waterloo has launched integrated postgraduate engineering programs within the Institute for Quantum Computing. Similar programs are being pursued at Delft University, Technical University of Munich, MIT, CentraleSupélec and other technical universities.
In the realm of undergraduate studies, opportunities for specialization are sparse. Nevertheless, some institutions have begun to offer programs. The Université de Sherbrooke offers a bachelor of science in quantum information, University of Waterloo offers a quantum specialization in its electrical engineering program, and the University of New South Wales offers a bachelor of quantum engineering.
Students are trained in signal and information processing, optoelectronics and photonics, integrated circuits (bipolar, CMOS) and electronic hardware architectures (VLSI, FPGA, ASIC). In addition, they are exposed to emerging applications such as quantum sensing, quantum communication and cryptography and quantum information processing. They learn the principles of quantum simulation and quantum computing, and become familiar with different quantum processing platforms, such as trapped ions, and superconducting circuits. Hands-on laboratory projects help students to develop the technical skills needed for the practical realization of quantum devices, consolidating their education in quantum science and technologies.
See also
Quantum supremacy
Noisy intermediate-scale quantum era
Timeline of quantum computing and communication
References
Engineering disciplines
Quantum mechanics | Quantum engineering | [
"Physics",
"Engineering"
] | 1,266 | [
"nan",
"Applied and interdisciplinary physics",
"Quantum mechanics",
"Applications of quantum mechanics"
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66,600,170 | https://en.wikipedia.org/wiki/Herelleviridae | Herelleviridae is a family of bacterial viruses of the order Caudovirales infecting members of the phylum Firmicutes. The family has five subfamilies, 33 genera and 92 species. In average, replication of family members is supported by 70% isolates of primary host species.
Etymology
The family's name, Herelle is in honor of Félix d'Hérelle, a French-Canadian microbiologist, the suffix -viridae is the standard suffix for virus families.
Taxonomy
The following subfamilies and genera are assigned to Herelleviridae (-virinae denotes subfamily and -virus denotes genus):
Bastillevirinae
Agatevirus
Bastillevirus
Bequatrovirus
Caeruleovirus
Eldridgevirus
Goettingenvirus
Grisebachstrassevirus
Jeonjuvirus
Matervirus
Moonbeamvirus
Nitunavirus
Shalavirus
Siophivirus
Tsarbombavirus
Wphvirus
Brockvirinae
Kochikohdavirus
Schiekvirus
Jasinkavirinae
Pecentumvirus
Spounavirinae
Okubovirus
Siminovitchvirus
Twortvirinae
Baoshanvirus
Kayvirus
Sciuriunavirus
Sepunavirus
Silviavirus
Twortvirus
The following genera are unassigned to a subfamily:
Elpedvirus
Harbinvirus
Hopescreekvirus
Mooreparkvirus
Salchichonvirus
Tybeckvirus
Watanabevirus
Lastly, the species Brochothrix virus A9 is unassigned to a subfamily and genus.
References
External links
Virus families | Herelleviridae | [
"Biology"
] | 316 | [
"Virus stubs",
"Viruses"
] |
66,600,257 | https://en.wikipedia.org/wiki/Battersia%20arctica | Battersia arctica is a species of algae belonging to the family Sphacelariaceae. In Iceland, it is listed as a critically endangered species (CR).
Synonym:
Sphacelaria arctica Harvey, 1858
References
Brown algae | Battersia arctica | [
"Biology"
] | 50 | [
"Algae",
"Brown algae"
] |
66,600,395 | https://en.wikipedia.org/wiki/Robert%20Carpick | Robert William Carpick is a Canadian mechanical engineer. He is currently director of diversity, equity, and inclusion and John Henry Towne Professor in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania. He is best known for his work in tribology, particularly nanotribology.
Education
Carpick received his bachelor's degree in physics from the University of Toronto in 1991, and his master's degree and Doctor of Philosophy in physics from the University of California, Berkeley, in 1997. His thesis was entitled "The Study of Contact, Adhesion and Friction at the Atomic Scale by Atomic Force Microscopy". His PhD supervisor was Miquel Salmeron, who pioneered the use of Atomic Force Microscopy (AFM) in tribology. During his PhD, Carpick devised a method to obtain reproducible and quantitative friction measurements using AFM.
Research career
After his PhD, he spent two years as a postdoctoral appointee at Sandia National Laboratory in the Surface and Interface Science Department, and then the Biomolecular Materials and Interfaces Department, where he worked under the supervision of Dr Alan R. Burns. In 2000, he joined the faculty at the University of Wisconsin-Madison in the Engineering Physics Department. Carpick moved to the University of Pennsylvania in January 2007.
He has made a number of important discoveries in the field of nanotribology using AFM. These include that the friction of lamellar 2D-materials (e.g. graphene, molybdenum disulfide, niobium diselenide, and hexagonal boron nitride) increases as the number of layers decreases. He has shown that frictional ageing of the contacts between rock surfaces arises from the formation of interfacial chemical bonds. He found that the wear of AFM tips cannot be adequately described by macroscale models and instead is driven by nanoscale mechanochemical processes. His group has also given important insights into the mechochemical tribofilm formation of the lubricant antiwear additive zinc dialkyldithiophosphate (ZDDP). According to Google Scholar, as of 2021, his work had been cited on over 16,000 occasions.
Honours and awards
Carpick was named a Fellow of the American Physical Society in 2012, a Fellow of the American Vacuum Society in 2014, a Fellow of the Society of Tribologists and Lubrication Engineers in 2016, a Fellow of the Materials Research Society in 2017, and a Fellow of the American Society of Mechanical Engineers (ASME) in 2019. He received a National Science Foundation CAREER Award in 2001, and was named Outstanding New Mechanics Educator by the American Society for Engineering Education in 2003. In 2009, he was awarded the ASME Burt L. Newkirk Award.
Personal life
Carpick has been married to his partner since 2003. He is also a fan and practitioner of curling and the organ.
References
Tribologists
University of Pennsylvania faculty
Year of birth missing (living people)
Living people
Canadian LGBTQ scientists
Canadian LGBTQ academics
21st-century Canadian LGBTQ people
Fellows of the American Physical Society | Robert Carpick | [
"Materials_science"
] | 638 | [
"Tribology",
"Tribologists"
] |
66,600,846 | https://en.wikipedia.org/wiki/Backbone-dependent%20rotamer%20library | In biochemistry, a backbone-dependent rotamer library provides the frequencies, mean dihedral angles, and standard deviations of the discrete conformations (known as rotamers) of the amino acid side chains in proteins as a function of the backbone dihedral angles φ and ψ of the Ramachandran map. By contrast, backbone-independent rotamer libraries express the frequencies and mean dihedral angles for all side chains in proteins, regardless of the backbone conformation of each residue type. Backbone-dependent rotamer libraries have been shown to have significant advantages over backbone-independent rotamer libraries, principally when used as an energy term, by speeding up search times of side-chain packing algorithms used in protein structure prediction and protein design.
History
The first backbone-dependent rotamer library was developed in 1993 by Roland Dunbrack and Martin Karplus to assist the prediction of the Cartesian coordinates of a protein's side chains given the experimentally determined or predicted Cartesian coordinates of its main chain. The library was derived from the structures of 132 proteins from the Protein Data Bank with resolution of 2.0 Å or better. The library provided the counts and frequencies of χ1 or χ1+χ2 rotamers of 18 amino acids (excluding glycine and alanine residue types, since they do not have a χ1 dihedral) for each 20° x 20° bin of the Ramachandran map (φ,ψ = -180° to -160°, -160° to -140° etc.).
In 1997, Dunbrack and Fred E. Cohen at the University of California, San Francisco presented a backbone-dependent rotamer library derived from Bayesian statistics. The Bayesian approach provided the opportunity for the definition of a Bayesian prior for the frequencies of rotamers in each 10° x 10° bin derived by assuming that the steric and electrostatic effects of the φ and ψ dihedral angles are independent. In addition, a periodic kernel with 180° periodicity was used to count side chains 180° away in each direction from the bin of interest. As an exponent of a sin2 function, it behaved much like a von Mises distribution commonly used in directional statistics. The 1997 library was made publicly available via the World Wide Web in 1997, and found early use in protein structure prediction and protein design. The library derived from Bayesian statistics was updated in 2002
Many modeling programs, such as Rosetta, use a backbone-dependent rotamer library as a scoring function (usually in the form E=-ln(p(rotamer(i) | φ,ψ)) for the ith rotamer, and optimize the backbone conformation of proteins by minimizing the rotamer energy with derivatives of the log probabilities with respect to φ,ψ. This requires smooth probability functions with smooth derivatives, because most mathematical optimization algorithms use first and sometimes second derivatives and will get stuck in local minima on rough surfaces. In 2011, Shapovalov and Dunbrack published a smoothed backbone-dependent rotamer library derived from kernel density estimates and kernel regressions with von Mises distribution kernels on the φ,ψ variables. The treatment of the non-rotameric degrees of freedom (those dihedral angles not about sp3-sp3 bonds, such as asparagine and aspartate χ2, phenylalanine, tyrosine, histidine, tryptophan χ2, and glutamine and glutamate χ3) was improved by modeling the dihedral angle probability density of each of these dihedral angles as a function of χ1 rotamer (or χ1 and χ2 for Gln and Glu) and φ,ψ. The functions are essentially regressions of a periodic probability density on a torus.
In addition to statistical analysis of structures in the Protein Data Bank, backbone-dependent rotamer libraries can also be derived from molecular dynamics simulations of proteins, as demonstrated by the Dynameomics Library from Valerie Daggett's research group. Because these libraries are based on sampling from simulations, they can generate far larger numbers of data points across regions of the Ramachandran map that are sparsely populated in experimental structures, leading to higher statistical significance in these regions. Rotamer libraries derived from simulations are dependent on the force field used in the simulations. The Dynameomics Library is built on simulations using the ENCAD force field of Levitt et al. from 1995.
Backbone-dependence of rotamer populations
The effect of backbone conformation on side-chain rotamer frequencies is primarily due to steric repulsions between backbone atoms whose position is dependent on φ and ψ and the side-chain γ heavy atoms (carbon, oxygen, or sulfur) of each residue type (PDB atom types CG, CG1, CG2, OG, OG1, SG). These occur in predictable combinations that depend on the dihedrals connecting the backbone atoms to the side-chain atoms. These steric interactions occur when the connecting dihedral angles form a pair of dihedral angles with values {-60°,+60°} or {+60°,-60°}, in a manner related to the phenomenon of pentane interference. For example, the nitrogen atom of residue i+1 is connected to the γ heavy atom of any side chain by a connected set of 5 atoms: N(i+1)-C(i)-Cα(i)-Cβ(i)-Cγ(i). The dihedral angle N(i+1)-C(i)-Cα(i)-Cβ(i) is equal to ψ+120°, and C(i)-Cα(i)-Cβ(i)-Cγ(i) is equal to χ1-120°. When ψ is -60° and χ1 is +60° (the g+ rotamer of a side chain), there is a steric interaction between N(i+1) and Cγ because the dihedral angles connecting them are N(i+1)-C(i)-Cα(i)-Cβ(i) = ψ+120° = +60°, and C(i)-Cα(i)-Cβ(i)-Cγ(i) = χ1-120° = -60°. The same interaction occurs when ψ is 0° and χ1 is 180° (the trans rotamer of a side chain). The carbonyl oxygen of residue i plays the same role when ψ=-60° for the g+ rotamer and when ψ=180° for the trans rotamer. Finally, φ-dependent interactions occur between the side-chain γ heavy atoms in g- and g+ rotamers on the one hand, and the carbonyl carbon of residue i-1 and a γ heavy atom, and between the backbone NH of residue i and its hydrogen-bonding partner on the other.
The φ,ψ-dependent interactions of backbone atoms and side-chain Cγ atoms can be observed in the distribution of observations in the Ramachandran plot of each χ1 rotamer (marked in the figure). At these positions, the Ramachandran populations of the rotamers are significantly reduced. They can be summarized as follows:
Side-chain types with two heavy atoms (Val, Ile, Thr) have backbone-dependent interactions with both heavy atoms. Val has CG1 at χ1 and CG2 at χ1+120°. Because Val g+ and g- conformations have steric interactions with the backbone near ψ=120° and -60° (the most populated ψ ranges), Val is the only amino acid where the t rotamer (χ1~180°) is the most common. At most values of φ and ψ, only one rotamer of Val is allowed (shown in figure). Ile has CG1 at χ1 and CG2 at χ1-120°. Thr has OG1 at χ1 and CG2 at χ1-120°.
Uses
The Dunbrack backbone-dependent rotamer library is used in a number of programs for protein structure prediction and computational design, including:
Side-chain conformation prediction in protein structure modeling
Swiss-model and its software, ProMod3
Rosetta
I-TASSER
Phyre
OEChem TK
YASARA
GalaxyRefine
SCWRL4
Protein Design
Rosetta
EvoEF2
Visualization of Protein Mutations
PyMol
UCSF Chimera
References
External links
Dunbrack 2010 Backbone-Dependent Rotamer Library
Protein Side-chain Conformational Analysis
Richardson Backbone-Independent Rotamer Libraries.
Dynameomics Backbone-Independent and Backbone-Dependent Rotamer Libraries
Protein structure
Bioinformatics
Molecular modelling | Backbone-dependent rotamer library | [
"Chemistry",
"Engineering",
"Biology"
] | 1,843 | [
"Biological engineering",
"Molecular physics",
"Bioinformatics",
"Theoretical chemistry",
"Molecular modelling",
"Structural biology",
"Protein structure"
] |
66,600,957 | https://en.wikipedia.org/wiki/Neolecta%20vitellina | Neolecta vitellina is a species of fungus belonging to the family Neolectaceae.
It has cosmopolitan distribution.
References
Ascomycota
Fungus species | Neolecta vitellina | [
"Biology"
] | 35 | [
"Fungi",
"Fungus species"
] |
66,601,521 | https://en.wikipedia.org/wiki/Time%20Lord%20Victorious | Time Lord Victorious is a multiplatform story set within the British science fiction television series Doctor Who. The story was announced in April 2020. The first instalment of the story was released in March 2020, and the final instalment was made available in April 2021 as a ticketed live experience. The serialised story is told through a variety of multimedia including audio dramas, comics, books, short stories, immersive experiences, collectables, and an animated series.
The title refers to an alias The Doctor assumed, claiming his supremacy over time, and final victory in the Time War.
Plot
The overall storyline includes events linking back to the Fourth Doctor's era, but essentially begins for the Tenth Doctor just after the events of "The Waters of Mars".
The Doctor's actions on Bowie Base One having created a temporal rift, he travels back to the Dark Times of the universe, where he meets the race known as the Kotturuh, who brought death itself into the universe in the early days of history, either making species mortal or killing them in a matter of hours for nothing more than the Kotturuhs' belief that they would contribute nothing to the future. The Doctor gathers an army of mercenaries and even goes so far as to create a virus based on the Kotturuhs' death touch that gives the entire species a 'lifespan' of fifteen minutes, eventually adopting the 'Time Lord Victorious' title as he tries to stop the Kotturuh's influence on history in the first place.
In the future, the Eighth Doctor discovers various temporal anomalies that he eventually traces back to the Dark Times, and he is forced to accompany a Dalek Time Squad into the past to investigate the source. The Ninth Doctor finds himself in the past while on a trip with Rose, and has to save a group of vampires from a previously-unknown female incarnation of Rassilon. The three Doctors meet about the Kotturuh homeworld, but the Tenth initially assumes that the Eighth and Ninth Doctors are a deception, resulting in the three fleets attacking each other until the Doctors make telepathic contact with each other. The Daleks attempt to steal samples from a Great Vampire in the Ninth's coffin ship to create a group of immortal Dalek/vampire hybrids, but the Doctors are able to find the last of the Kotturuh, who had abandoned her peoples' vendetta, and convince her to kill the Dalek hybrids. The Eighth Doctor takes the Dalek squad back into the Time Vortex, and the Ninth and Tenth are able to find a new planet for the vampires to settle on with the aid of a blood substitute.
The Eighth Doctor is able to destroy the Dalek saucer and escape, but a single Dalek survives and is picked up by a colony ship, but is eventually destroyed by the Fourth Doctor. The Tenth Doctor also takes the opportunity to tie up a loose end left by the Eighth Doctor, in the form of a telepathic entity that the Eighth defeated but was unable to properly trap at the time.
Multimedia
Animated series
Daleks!
Daleks! is an animated series based on the eponymous fictional extra-terrestrial race of mutants from the British science fiction television series Doctor Who. The series was written by James Goss as the final instalment in the multi-platform story arc Time Lord Victorious. The series was released in 5 weekly 10-minute episodes from 12 November 2020 on the official Doctor Who YouTube channel. The CGI animation was created by Studio Liddell. The cast includes Nicholas Briggs as the Daleks, Joe Sugg as R-41, Anjli Mohindra as the Mechanoid Queen, and Ayesha Antoine as Mechonoid 2150 and the Chief Archivist.
Following the previous events of Time Lord Victorious, the Daleks ransack the Archive of Islos, only to find that their home planet Skaro has been invaded. Huw Fullerton wrote in Radio Times that the series was "an enjoyable little corner of the Doctor Who universe", although he criticized the visual effects as "a little lacklustre". Aidan Mason of Pop Culture Beast stated that, "this series is a decent watch, especially Planet of the Mechanoids", but stated that the finale was, "full of holes and tropes, as well as slightly rushed."
Live experiences
Doctor Who: Time Fracture
Doctor Who: Time Fracture is an immersive experience offered by UK company Immersive Everywhere in collaboration with the BBC.
The experience is to be set across multiple times and worlds within the area that the experience is hosted, Mayfair. The experience will see attendees follow a story across multiple time periods, interact with characters from the Doctor Who universe, and encounter recurring adversaries including the Daleks and the Cybermen.
The immersive experience Time Fracture was due to launch 17 February 2021, but was postponed due to the COVID-19 pandemic. The experience launched on 21 April 2021.
A Dalek Awakens
A Dalek Awakens is an escape room game provided by UK based Escape Hunt Group Ltd in collaboration with the BBC. The escape room launched in March 2020 and was later revealed to be part of Time Lord Victorious. It is available at venues in Birmingham and Reading, and is due to be made available in Norwich and Basingstoke. Players board a mock spaceship and have to solve puzzles in order to prevent an invading Dalek from destroying them and the passengers aboard.
Audio dramas
All audio productions were produced by Big Finish Productions, except The Minds of Magnox, which was produced by BBC Audio. Reviewing Lesser Evils and Master Thief, Bryn Mitchell of We Are Cult stated that, "Like many of Big Finish’s Short Trips, these stories combine a cheap price with quality production, an elegant reading, and just plain good storytelling."
Big Finish Productions
BBC Audio
The Minds of Magnox
Books
All Flesh Is Grass – BBC Books
The Knight, the Fool and The Dead – BBC Books
The Wintertime Paradox – Penguin Books
Short stories
The Dawn of Kotturuh – Released on the BBC Doctor Who mailing list
The Last Message – Included with Doctor Who Figurine Collection: Time Lord Victorious #1 – Hero Collector
Mission to the Known – Included with Doctor Who Figurine Collection: Time Lord Victorious #2 – Hero Collector
Exit Strategy – Included with Doctor Who Figurine Collection: Time Lord Victorious #3 – Hero Collector
The Guide to the Dark Times – Released in the Doctor Who Annual 2021 – Penguin Books
Comics
Defender of the Daleks – Titan Comics
Monstrous Beauty – Doctor Who Magazine
Tales of the Dark Times – via Doctor Who: Comic Creator app
Blu-ray collection
Time Lord Victorious: Road to the Dark Times is a compendium of previously released television stories which link to the larger Time Lord Victorious narrative. The stories included are:
Planet of the Daleks (1973)
Genesis of the Daleks (1975)
The Deadly Assassin (1976)
State of Decay (1980)
The Curse of Fenric (1989)
"The Runaway Bride" (2006)
"The Waters of Mars" (2009)
References
Doctor Who stories
Multimedia works
Works based on Doctor Who | Time Lord Victorious | [
"Technology"
] | 1,455 | [
"Multimedia",
"Multimedia works"
] |
66,603,406 | https://en.wikipedia.org/wiki/Barbara%20Hulme | Barbara Hulme (née Poulter; 1930–2020) was a botanist, credited with being the first to produce experimental hybrids in the genus Atriplex (also known as saltbush or orache), a genus of wild flower common on seaside strandlines. The Canadian botanist Pierre Michel Taschereau would later name the Atriplex X hulmeana hybrid after her.
Early life and education
Born in York, Barbara attended Tang Hall Junior School in the Heworth area of the city, before gaining a scholarship to attend Queen Anne Grammar School.
University and research
Barbara studied botany at the University of Edinburgh from 1948 where she achieved a first class degree. She stayed on to study for a PhD, which she gained in 1957. Her thesis was entitled "Studies on some British species of Atriplex L", in which she clarified the classification of four british Atriplex species, performed cultivation studies including hybridization, and revealed that many of the traits used for classification are genetically determined but can be influenced by environmental factors. She also assisted botanist Peter Hadland Davis in his study of the flora of Turkey.
Marriage and later life
It was also during her time at Edinburgh that she met her future husband Ken Hulme, who was then working as a foreman at the Royal Botanical Gardens Edinburgh. The couple married in 1955 and moved first to Birmingham, where Barbara finished writing up her thesis, and then to the Wirral in 1957, where Ken had become the first Director at Ness Gardens, University of Liverpool. After the birth of her three children, Barbara's life revolved around caring for them and other family members but her interest in plants stayed with her for the rest of her life, and many of her holidays with Ken, including a trip to China to attend a symposium about botanic gardens, revolved around plants and gardens.
References
Alumni of the University of Edinburgh
1930 births
2020 deaths
English botanists
Scientists from York
Hybrid plants
British women botanists | Barbara Hulme | [
"Biology"
] | 400 | [
"Hybrid plants",
"Plants",
"Hybrid organisms"
] |
66,604,191 | https://en.wikipedia.org/wiki/Harmen%20Blok | Harmen Blok was a Dutch mechanical engineer. He was best known for his work in the field of tribology.
Early life and education
Blok was born on 8 September 1910 in Amsterdam. He was the son of Pieter Engel Johannes Blok and Wikje Harmina Poort.
He graduated with a degree in mechanical engineering from Delft University of Technology in 1932.
He died on 16 August 2000 in The Hague.
Research
After graduating from the Delft University of Technology, and a short period as research assistant, Harmen Blok joined the Delft Laboratory of the Royal Dutch Shell Group in 1933, to work on the fundamentals of lubrication. He left Shell in 1951 to take up a position as Professor of Mechanical Engineering at Delft University of Technology. Here, along with Professor Boerlage, he developed the now ubiquitous four-ball wear tester. One of his key contributions was the prediction of flash temperature rise inside rubbing contacts. He also worked on thin-film fluid lubrication and gear tribology.
He was a Fellow of the American Society Mechanical Engineers and the Institution of Mechanical Engineers. In 1973, he was awarded the Tribology Gold Medal from the Institution of Mechanical Engineers.
He was a founding member of the International Tribology Council (ITC).
References
1910 births
2000 deaths
Academic staff of the Delft University of Technology
Delft University of Technology alumni
Dutch mechanical engineers
Tribologists | Harmen Blok | [
"Materials_science"
] | 292 | [
"Tribology",
"Tribologists"
] |
66,604,524 | https://en.wikipedia.org/wiki/Tambja%20amitina | Tambja amitina is a species of sea slug, a dorid nudibranch, a marine gastropod mollusk in the family Polyceridae. It is currently considered to be a nomen dubium.
Distribution
This species was originally described from Indonesia.
References
Polyceridae
Gastropods described in 1905
Nomina dubia | Tambja amitina | [
"Biology"
] | 67 | [
"Biological hypotheses",
"Nomina dubia",
"Controversial taxa"
] |
69,459,821 | https://en.wikipedia.org/wiki/Japanese%20Federation%20of%20Synthetic%20Chemistry%20Workers%27%20Unions | The Japanese Federation of Synthetic Chemistry Workers' Unions (, Gokaroren) was a trade union representing workers in the chemical industry in Japan.
The union was founded in 1950, with the merger of two unions representing ammonium sulfate and phosphate workers. The same year, it was a founding affiliate of the General Council of Trade Unions of Japan (Sohyo). From 1953 until 1957, it was chaired by Ōta Kaoru. By 1967, it had 121,324 members.
The union was affiliated with the Japanese Trade Union Confederation from the late 1980s, and by 1996, it had 91,242 members. The All Japan Chemistry Workers' Union split away in 1987, but merged with Goka Roren in 1998 to form the Japanese Federation of Chemistry Workers' Unions.
References
Chemical industry trade unions
Trade unions established in 1950
Trade unions disestablished in 1998
Trade unions in Japan | Japanese Federation of Synthetic Chemistry Workers' Unions | [
"Chemistry"
] | 180 | [
"Chemical industry trade unions"
] |
69,459,968 | https://en.wikipedia.org/wiki/National%20Federation%20of%20Cement%20Workers%27%20Unions%20of%20Japan | The National Federation of Cement Workers' Unions of Japan (, Zenkoku Semento) was a trade union representing workers involved in manufacturing cement in Japan.
The union was founded in 1947, and was later a founding affiliate of the Federation of Independent Unions (Churitsuroren). By 1967, it had 26,855 members. In the late 1980s, it affiliated to the Japanese Trade Union Confederation, but by 1996 it had only 7,263 members remaining. In 2002, it merged with the Japanese Federation of Chemistry Workers' Unions, the National Organization of All Chemical Workers and the Japan Confederation of Petroleum Industry Workers' Unions, to form the Japan Federation of Energy and Chemistry Workers' Unions.
References
Chemical industry trade unions
Trade unions established in 1947
Trade unions disestablished in 2002
Trade unions in Japan | National Federation of Cement Workers' Unions of Japan | [
"Chemistry"
] | 164 | [
"Chemical industry trade unions"
] |
69,460,028 | https://en.wikipedia.org/wiki/Japan%20Confederation%20of%20Petroleum%20Industry%20Workers%27%20Unions | The Japan Confederation of Petroleum Industry Workers' Unions (, Sekiyu Roren) was a trade union representing workers in the oil industry in Japan.
The union was founded on 11 April 1947 as a loose council and became a more centralised federation in 1953. It was initially known as the All Japan Oil Workers' Union (Zensekiyu). It was a founding affiliate of the Federation of Independent Unions (Churitsuroren), and by 1967, it had 24,611 members. In the late 1980s, it became affiliated with the Japanese Trade Union Confederation, and by 1996 it had 29,505 members. In 2002, it merged with the Japanese Federation of Chemistry Workers' Unions, the National Organization of All Chemical Workers, and the National Federation of Cement Workers' Unions of Japan to form the Japan Federation of Energy and Chemistry Workers' Unions.
References
Chemical industry trade unions
Trade unions established in 1947
Trade unions disestablished in 2002
Trade unions in Japan | Japan Confederation of Petroleum Industry Workers' Unions | [
"Chemistry"
] | 197 | [
"Chemical industry trade unions"
] |
69,460,867 | https://en.wikipedia.org/wiki/Contour%20currents | The term contour currents was first introduced by Heezen et al in 1966 as bottom currents along the continental shelf driven by Coriolis effects and temperature/salinity dependent density gradients. Generally, the currents flow along depth contours, hence called contour currents. Sediments deposited and shaped by the contour currents are called contourites, which are commonly observed in continental rise.
Depositional Processes
Since contour currents generally flow at speed of 2–20 cm/s, their capacity to carry sediments is limited to fine grain particles already in suspension. Redistribution of sediments by contour currents have, however, been reported as evidenced by the sea floor morphological features parallel to regional isobaths.
Turbidity currents, on the other hand, flow down slope across regional isobaths and are mainly responsible for supplying terrigenous sediment across continental margins to deep-water environments, such as continental rise, where fine particles are further carried in suspension by contour currents. The joint depositional processes of the two current systems contribute to the dominant factors influencing the morphology of the lower continental margins.
References
Gradient methods
Oceanography
Geology | Contour currents | [
"Physics",
"Environmental_science"
] | 229 | [
"Oceanography",
"Hydrology",
"Applied and interdisciplinary physics"
] |
69,461,001 | https://en.wikipedia.org/wiki/Miniopterid%20betaherpesvirus%201 | Miniopterid betaherpesvirus 1 (MschBHV1) is a species of virus in the genus Quwivirus in the subfamily Betaherpesvirinae, family Herpesviridae, and order Herpesvirales.
References
Betaherpesvirinae | Miniopterid betaherpesvirus 1 | [
"Biology"
] | 57 | [
"Virus stubs",
"Viruses"
] |
69,461,042 | https://en.wikipedia.org/wiki/Macacine%20alphaherpesvirus%202 | Macacine alphaherpesvirus 2 (McHV-2) is a species of virus in the genus Simplexvirus, subfamily Alphaherpesvirinae, family Herpesviridae, and order Herpesvirales.
References
Alphaherpesvirinae | Macacine alphaherpesvirus 2 | [
"Biology"
] | 55 | [
"Virus stubs",
"Viruses"
] |
69,461,045 | https://en.wikipedia.org/wiki/Macacine%20alphaherpesvirus%203 | Macacine alphaherpesvirus 3 (McHV-3) is a species of virus in the genus Simplexvirus, subfamily Alphaherpesvirinae, family Herpesviridae, and order Herpesvirales.
References
Alphaherpesvirinae | Macacine alphaherpesvirus 3 | [
"Biology"
] | 55 | [
"Virus stubs",
"Viruses"
] |
69,461,071 | https://en.wikipedia.org/wiki/Cervid%20alphaherpesvirus%203 | Cervid alphaherpesvirus 3 (CvHV-3) is a species of virus in the genus Varicellovirus, subfamily Alphaherpesvirinae, family Herpesviridae, and order Herpesvirales.
References
Alphaherpesvirinae | Cervid alphaherpesvirus 3 | [
"Biology"
] | 56 | [
"Virus stubs",
"Viruses"
] |
69,461,111 | https://en.wikipedia.org/wiki/TNet | TNet is a secure top-secret-level intranet system in the White House, notably used to record information about telephone and video calls between the President of the United States and other world leaders. TNet is connected to Joint Worldwide Intelligence Communications System (JWICS), which is used more widely across different offices in the White House. Contained within TNet is an even more secure system known as NSC Intelligence Collaboration Environment (NICE).
NSC Intelligence Collaboration Environment
The NSC Intelligence Collaboration Environment (NICE) is a computer system operated by the United States National Security Council's Directorate for Intelligence Programs. A subdomain of TNet, it was created to enable staff to produce and store documents, such as presidential findings or decision memos, on top secret codeword activities. Due to the extreme sensitivity of the material held on it, only about 20 percent of NSC staff can reportedly access the system. The documents held on the system are tightly controlled and only specific named staff are able to access files.
The system became the subject of controversy during the Trump–Ukraine scandal, when a whistleblower complaint to the Inspector General of the Intelligence Community revealed that NICE had been used to store transcripts of calls between President Donald Trump, and foreign leaders, apparently to restrict access to them. The system was reportedly used for this purpose from 2017 after leaks of conversations with foreign leaders. It was said to have been upgraded in the spring of 2018 to log, who had accessed particular files, as a deterrent against possible leaks.
See also
Classified website
Intellipedia
Joint Worldwide Intelligence Communications System (JWICS)
NIPRNet
RIPR
SIPRNet
References
Computer systems
United States National Security Council
Wide area networks
United States government secrecy | TNet | [
"Technology",
"Engineering"
] | 350 | [
"Computer engineering",
"Computer network stubs",
"Computer systems",
"Computer science",
"Computing stubs",
"Computers"
] |
69,461,148 | https://en.wikipedia.org/wiki/Bossavirus | Bossavirus is a genus of viruses in the subfamily Gammaherpesvirinae, in the family Herpesviridae, in the order Herpesvirales. It contains the sole species Delphinid gammaherpesvirus 1.
References
Gammaherpesvirinae
Virus genera | Bossavirus | [
"Biology"
] | 58 | [
"Virus stubs",
"Viruses"
] |
69,461,173 | https://en.wikipedia.org/wiki/Manticavirus | Manticavirus is a genus of viruses in the subfamily Gammaherpesvirinae, in the family Herpesviridae, in the order Herpesvirales. This genus was the only genus to consist entirely of marsupial-hosted species as of the time of naming, hence the name component Mantica (Latin: knapsack), in reference to the marsupial pouch.
Species
The genus includes the following species:
Phascolarctid gammaherpesvirus 1
Vombatid gammaherpesvirus 1
References
Gammaherpesvirinae
Virus genera | Manticavirus | [
"Biology"
] | 116 | [
"Virus stubs",
"Viruses"
] |
69,461,189 | https://en.wikipedia.org/wiki/Patagivirus | Patagivirus is a genus of viruses in the subfamily Gammaherpesvirinae, in the family Herpesviridae, in the order Herpesvirales. It contains the sole species Vespertilionid gammaherpesvirus 3.
References
Gammaherpesvirinae
Virus genera | Patagivirus | [
"Biology"
] | 59 | [
"Virus stubs",
"Viruses"
] |
69,461,217 | https://en.wikipedia.org/wiki/Phascolarctid%20gammaherpesvirus%201 | Phascolarctid gammaherpesvirus 1 (PhaHV-1) is a species of virus in the genus Manticavirus, subfamily Gammaherpesvirinae, family Herpesviridae, and order Herpesvirales.
Host
It is hosted by the koala (Phascolarctos cinereus).
References
Gammaherpesvirinae | Phascolarctid gammaherpesvirus 1 | [
"Biology"
] | 76 | [
"Virus stubs",
"Viruses"
] |
69,461,222 | https://en.wikipedia.org/wiki/Vombatid%20gammaherpesvirus%201 | Vombatid gammaherpesvirus 1 (VoHV-1) is a species of virus in the genus Manticavirus, subfamily Gammaherpesvirinae, family Herpesviridae, and order Herpesvirales.
Host
It is hosted by the common wombat (Vombatus ursinus).
References
Gammaherpesvirinae | Vombatid gammaherpesvirus 1 | [
"Biology"
] | 74 | [
"Virus stubs",
"Viruses"
] |
69,462,019 | https://en.wikipedia.org/wiki/Simplex%20tree | In topological data analysis, a simplex tree is a type of trie used to represent efficiently any general simplicial complex. Through its nodes, this data structure notably explicitly represents all the simplices. Its flexible structure allows the implementation of many basic operations useful to computing persistent homology. This data structure was invented by Jean-Daniel Boissonnat and Clément Maria in 2014, in the article The Simplex Tree: An Efficient Data Structure for General Simplicial Complexes. This data structure offers efficient operations on sparse simplicial complexes. For dense or maximal simplices, Skeleton-Blocker representations or Toplex Map representations are used.
Definitions
Many researchers in topological data analysis consider the simplex tree to be the most compact simplex-based data structure for simplicial complexes, and a data structure allowing an intuitive understanding of simplicial complexes due to integrated usage of their mathematical properties.
Heuristic definition
Consider any simplicial complex is a set composed of points (0 dimensions), line segments (1 dimension), triangles (2 dimensions), and their n-dimensional counterparts, called n-simplexes within a topological space. By the mathematical properties of simplexes, any n-simplex is composed of multiple -simplexes. Thus, lines are composed of points, triangles of lines, and tetrahedrons of triangles. Notice each higher level adds 1 vertex to the vertices of the n-simplex. The data structure is simplex-based, therefore, it should represent all simplexes uniquely by the points defining the simplex. A simple way to achieve this is to define each simplex by its points in sorted order.
Let be a simplicial complex of dimension k, its vertex set, where vertices are labeled from 1 to and ordered accordingly. Now, construct a dictionary size containing all vertex labels in order. This represents the 0-dimensional simplexes. Then, for the path to the initial dictionary of each entry in the initial dictionary, add as a child dictionary all vertices fully-connected to the current set of vertices, all of which have a label greater than . Represent this step on k levels. Clearly, considering the first dictionary as depth 0, any entry at depth of any dictionary in this data structure uniquely represents a -simplex within . For completeness, the point to the initial dictionary is considered the representation of the empty simplex. For the practicality of the operations, labels that are repeated on the same level are linked together, forming a looped linked list. Finally, child dictionaries also have pointers to their parent dictionary, for fast ancestor access.
Constructive definition
Let be a simplicial complex of dimension k. We begin by decomposing the simplicial complex into mutually exclusive simplexes. This can be achieved in a greedy way by iteratively removing from the simplicial complex the highest order simplexes until the simplicial complex is empty. We then need to label each vertex from 1 to and associate each simplex with its corresponding "word", that is the ordered list of its vertices by label. Ordering the labels ensures no repetition in the simplex tree, as there is only one way to describe a simplex. We start with a null root, representing the null simplex. Then, we iterate through all simplexes, and through each label of each simplex word. If the label is available as a child to the current root, make that child the temporary root of the insertion process, otherwise, create a new node for the child, make it the new temporary root, and continue with the rest of the word. During this process, k dictionaries are maintained with all the labels and insert the address of the node for the corresponding label. If an address is already at that space in the dictionary, a pointer is created from the old node to the new node. Once the process is finished, all children of each node are entered into a dictionary, and all pointers are looped to make looped linked lists. A wide range of dictionaries could be applied here, like hash tables, but some operations assume the possibility of an ordered traversal of the entries, leading most of the implementations to use red-black trees are dictionaries.
Operations
While simplex trees are not the most space efficient data structures for simplicial complex representation, their operations on sparse data are considered state-of-art. Here, we give the bounds of different useful operations possible through this representation. Many implementations of these operations are available.
We first introduce the notation. Consider is a given simplex, is a given node corresponding to the last vertex of , is the label associate to that node, is the depth of that node, is the dimension of the simplicial complex, is the maximal number of operations to access in a dictionary (if the dictionary is a red-black tree, is the complexity) . Consider is the number of cofaces of , and is the number of nodes of the simplex tree ending with the label at depth greater than . Notice .
Search, insert and remove words are done in .
Insert and remove an entire simplex is done in .
Computing persistent homology, or in a more involved way, computing Betti numbers, using a simplex tree most efficiently remains an open problem, however, current algorithms for this task on sparse simplicial complexes achieve state-of-art performance.
The structure of simplex trees allows for elementary collapse of collapsible simplexes, however the bounds of this operation in the general case are unknown.
A subcase of elementary collapse is edge-contraction. Edge contraction can be
achieved in .
Locating cofaces of given simplex can be achieved in .
Locating cofacets of given simplex can be achieved in .
As for construction, as seen in the constructive definition, construction is proportional to the number and complexity of simplexes in the simplicial complex. This can be especially expensive if the simplicial complex is dense. However, some optimizations for particular simplicial complexes, including for Flag complexes, Rips complexes and Witness complexes.
Applications
Simplex trees are efficient in sparse simplicial complexes. For this purpose, many persistent homology algorithms focusing on high-dimensional real data (often sparse) use simplex trees within these algorithms. While simplex trees are not as efficient as incidence matrices, their simplex-based structure allows them to be useful and efficient for simplicial complex storage within persistent homology algorithms.
References
Trees (data structures)
Simplicial sets | Simplex tree | [
"Mathematics"
] | 1,349 | [
"Basic concepts in set theory",
"Families of sets",
"Simplicial sets"
] |
69,463,195 | https://en.wikipedia.org/wiki/Cryomicroscopy | Cryomicroscopy is a technique in which a microscope is equipped in such a fashion that the object intended to be inspected can be cooled to below room temperature. Technically, cryomicroscopy implies compatibility between a cryostat and a microscope. Most cryostats make use of a cryogenic fluid such as liquid helium or liquid nitrogen. There exists two common motivations for performing a cryomicroscopy. One is to improve upon the process of performing a standard microscopy. Cryogenic electron microscopy, for example, enables the studying of proteins with limited radiation damage. In this case, the protein structure may not change with temperature, but the cryogenic environment enables the improvement of the electron microscopy process. Another motivation for performing a cryomicroscopy is to apply the microscopy to a low-temperature phenomenon. A scanning tunnelling microscopy under a cryogenic environment, for example, allows for the studying of superconductivity, which does not exist at room temperature.
History
Although optical microscopes have existed for centuries, cryomicroscopy is a modern methodology. In the 1950s, ice crystals were studied by installing an electron microscope inside of an igloo. Circa 1980, the adaption of the electron microscope, the vacuum, and the cryostat led to the conception of the modern cryomicroscopy. This development of the cryoelectron microscopy led to the awarding of the 2017 Nobel Prize in Chemistry to Jacques Dubochet, Joachim Frank, and Richard Henderson.
Cryogenic electron microscopy
The processes of scanning and transmission electron microscopy carried out under cryogenic conditions are known as cryoSEM and cryoTEM, respectively.
Cryogenic optical microscopy
Cryogenic environments are used in combination with different types of optical microscopy techniques. Cryogenic environments also minimize bleaching, which, in turn, improves the contrast of the microscopy technique.
The growth of artificial ice crystals is, for example, studied by optical microscopy. With polarized light microscopy, the birefringence effect from, for example, orthorhombic domain structures, can be observed at cryogenic temperatures. In the field of biology, fluorescence microscopy has enabled resolution beyond the diffraction limit. The 2014 Nobel Prize in Chemistry was jointly awarded to Eric Betzig, Stefan Hell, and William E. Moerner for the development of super-resolved fluorescence microscopy.
References
Microscopes | Cryomicroscopy | [
"Chemistry",
"Technology",
"Engineering"
] | 484 | [
"Microscopes",
"Measuring instruments",
"Microscopy"
] |
69,466,761 | https://en.wikipedia.org/wiki/AofA%E2%80%94International%20Meeting%20on%20Combinatorial%2C%20Probabilistic%2C%20and%20Asymptotic%20Methods%20in%20the%20Analysis%20of%20Algorithms | AofA, the International Meeting on Probabilistic, Combinatorial and Asymptotic Methods for the Analysis of Algorithms is an academic meeting that has been held regularly since 1993 in the field of computer science, focusing on mathematical methods from analytic combinatorics and probability for the study of properties of algorithms and large combinatorial structures. In early years, different formal names were used, but the meeting and associated community of researchers has always been known as AofA.
Structure
The tradition is a weeklong meeting, alternating between invited workshops and open refereed conferences with contributed papers chosen by a program committee. The meetings feature invited presentations from senior researchers, about half from within the community and half from related research areas. Since 2014, the inaugural lecture at each conference has been delivered by the winner of the Flajolet Lecture Prize.
Publishing
The proceedings of the conferences are now published by the Schloss Dagstuhl Leibniz Center for Informatics in the open access series Leibniz International Proceedings in Informatics. The proceedings are freely available from the conference website and also from DROPS, the Dagstuhl Research Online Publication Server. The proceedings of prior editions have been published in several venues, and special issues of several journals have been devoted to papers from AofA conferences.
Related meetings
From 2002 to 2008, the community organized a second meeting each even-numbered year, the Colloquium on Mathematics and Computer Science (MathInfo). Due to overlap among participants and content, the community decided to merge the two meetings to the present format. From 2003 to 2019, the AofA community also organized the one-day ANALCO meetings at the SODA conference.
The community has also organized symposia and special journal issues to celebrate Donald Knuth’s 1,000,0002 birthday, to celebrate Philippe Flajolet’s 60th birthday, to honor the memory of Phillipe Flajolet, and to celebrate Don Knuth’s 80th birthday.
AofA conferences are indexed by several bibliographic databases, including the DBLP, Google Scholar and The Collection of Computer Science Bibliographies.
History
AofA meetings have been held regularly since 1993 in Europe and North America, usually in the summer. Refereed conferences are in bold.
1993 Schloss Dagstuhl, Germany. Proceedings.
1995 Schloss Dagstuhl, Germany. Proceedings.
1997 Schloss Dagstuhl, Germany. Proceedings.
1998 Princeton, NJ, USA. Proceedings.
1999 Barcelona, Spain.
2000 Krynica Morska, Poland. Proceedings
2000 Versailles, France. MathInfo Proceedings.
2001 Tatihou, France.
2002 Strobl, Austria. Proceedings.
2002 Versailles, France. MathInfo Proceedings.
2003 San Miniato, Italy (Speakers: Ralph Neininger; Luc Devroye; Brigitte Vallée; Philippe Flajolet; Brendan McKay)
2004 MSRI, Berkeley, USA (Speakers: Persi Diaconis; Philippe Flajolet; Donald Knuth; Richard M. Karp). Proceedings.
2004 Vienna, Austria. MathInfo Proceedings.
2005 Barcelona, Spain (Speakers: Alan M. Frieze; Gábor Lugosi; Nicholas Pippenger; Helmut Prodinger; Robert Sedgewick). Proceedings.
2006 Alden Biesen, Belgium. (Speakers: Philippe Chassaing; Erik Demaine; Philippe Flajolet; Hsien- Kuei Hwang; Svante Janson; Guy Louchard; Bruce Reed).
2006 Nancy, France. MathInfo Proceedings.
2007 Juan-les-pins, France (Speakers: Persi Diaconis; Madhu Sudan; Wojciech Szpankowski; Mireille Bousquet-Melou; Luc Devroye; Philippe Flajolet). Proceedings
2008 Maresias, Brazil. (Speakers: John Dixon; Gaston Gonnet; Jean-François Marckert; Conrado Martínez; Brendan D. McKay; Andrea Montanari; Robert Sedgewick; Brigitte Vallée)
2008 Blaubeuren, Germany. MathInfo Proceedings.
2009 Fréjus, France. (Speakers: Brigitte Chauvin; Jérémie Bouttier; Bernhard Gittenberger; Philippe Jacquet; Marc Noy; Uwe Roesler; David Sankoff; Gilles Schaeffer)
2010 Vienna, Austria. (Speakers: Noga Alon; Yuliy Baryshnikov; Daniel Panario; Oliver Riordan; Peter Winkler). Proceedings.
2011 Będlewo, Poland. (Speakers: Julien Clément; Jim Fill; Hsein-Kuei Hwang; Piotr Indyk; Michal Karonski; Marc Mézard; Ralph Neininger; Angelica Steger))
2012 Montreal, Canada. (Speakers: Amin Coja-Oghlan; Michael Drmota; Svante Janson; Claire Mathieu; Avi Wigderson). Proceedings.
2013 Menorca, Spain. (Speakers: Joachim Buhmann; Rudolf Grübel; Mihyun Kang; Gabor Lugosi; Cyril Nicaud; Konstantinos Panagiotou; Michèle Soria; Alfredo Viola)
2014 Paris, France. (Flajolet lecture: Donald Knuth. Speakers: Manuel Kauers; Colin McDiarmid; Christopher Moore; Marc Noy; Gilles Schaeffer). Proceedings.
2015 Strobl, Austria. (Speakers: Nicolas Broutin; Christina Goldschmidt; Martin Dietzfelbinger; Elchanan Mossel; Markus Nebel; Alois Panholzer; Carsten Schneider; Lutz Warnke)
2016 Krakow, Poland. (Flajolet lecture: Robert Sedgewick. Speakers: Jean Bertoin; Pawel Blasiak; Hsien- Kuei Hwang; Wojciech Szpankowski; Nick Wormald. Proceedings.
2017 Princeton, NJ, USA. (Speakers: Sourav Chatterjee; Michael Fuchs; Cecilia Holmgren; Marni Mishna; Dan Romik; Bruno Salvy; Neil J. A. Sloane; Perla Sousi)
2018 Uppsala, Sweden. (Flajolet lecture: Luc Devroye. Speakers: Louigi Addario-Berry; Béla Bollobás; Karen Gunderson; Olle Häggström; Svante Janson; Mihyun Kang; Mark Daniel Ward). Proceedings.
2019 Luminy, France. (Speakers: Alin Bostan; Valentin Féray; Peter Mörters; Cyril Nicaud; Robin Pemantle; Dana Randall; Andrea Sportiello; Lenka Zbedorova)
2020 Klagenfurt, Austria
2021 Klagenfurt, Austria (Virtual). (Panel discussion: "The Legacy of Philippe Flajolet: Ten Years Later" with the first four Flajolet Lecturers; Speakers: James A. Fill, Malwina Luczak, Andrew Rechnitzer)
2022 Philadelphia, USA. (Flajolet lectures: Wojciech Szpankowski and Svante Janson. Speakers: TBA).
References
External links
Bibliographic information about ANALCO at DBLP
Bibliographic information about AofA at DBLP
The Collection of Computer Science Bibliographies
Meetings
Computer science conferences
Recurring events established in 1993 | AofA—International Meeting on Combinatorial, Probabilistic, and Asymptotic Methods in the Analysis of Algorithms | [
"Technology"
] | 1,526 | [
"Computer science",
"Computer science conferences"
] |
69,467,164 | https://en.wikipedia.org/wiki/Manfred%20Schidlowski | Manfred Schidlowski (13 November 1933 – 3 October 2012) was a German Professor of Geochemistry at the Max-Planck-Institut for Chemistry (Otto-Hahn-Institut) in Mainz. His research was concerned with the biochemistry of the Early Earth with a focus on isotope-biogeochemistry and the evidence of the earliest life processes in Precambrian. Schidlowski is considered the founder of this research direction in Germany and he also shaped international research in isotope biogeochemistry of Precambrian sediments for more than two decades.
Biography and scientific work
Manfred Schidlowski was born in Stettin on 13 November 1933. His family left his homeland during the Second World War and moved to Greifswald. From 1952-1955 he studied at the Humboldt University of Berlin, and from 1956 at the Free University of Berlin, where he received his diploma in geology in 1960 and one year later his doctorate with the "Contribution to the Geology of the Eastern Alps between the Small Walser Valley and the Upper Lech (Vorarlberg, Austria)". His desire for a change in geoscientific content led him to South Africa, first as a postdoctoral researcher at the University of Pretoria and then as a mine geologist for the Anglo-Transvaal Consolidated Investment Co. Ltd. at the Loraine Gold Mine to Allanridge in the Orange Free State. In 1962 he met his future wife Ingrid Piegler, a great-great-granddaughter of Heinrich Gottfried Piegler, he married her in 1964.
Scientifically, he worked on the mineralogy of the gold-bearing Witwatersrand sequence. The discovery of detrital, i.e. sedimentary rearranged pyrites and uraninites as well as the frequently occurring carbonaceous material in these layers founded his scientific interest in the early evolution of the Earth and provided the data for his first Nature publication in 1965 with the title "Probable Life-forms from the Precambrian of the Witwatersrand System (South Africa)".
In 1963 Schidlowski returned to Germany to work on the ores of the Witwatersrand succession in Paul Ramdohr's group in the Heidelberg. Here the idea of a relationship between the presence of detrital pyrites and the oxygen content of the Earth's atmosphere was born. He spent the years 1965-1967 at the University of Göttingen. Evidence for a biological origin of the carbonaceous material in the Witwatersrand sediments was consolidated during this time by carbon isotope investigations in cooperation with Jochen Hoefs. Afterwards, Schidlowski habilitated at the University of Heidelberg. In 1969 he moved to the newly founded Institute for Air Chemistry at the Max Planck Institute for Chemistry in Mainz in 1969. Its director, Christian Junge, sent him back to South Africa on a large sampling campaign. The focus was on the carbonates of early Earth history as archives of ocean-atmosphere evolution. Among these were carbonates of the Lomagundi succession from Rhodesia (now Zimbabwe) with their unusually positive carbon isotopy. Initially classified as a local feature, it quickly became clear that this was a global phenomenon, one of the most massive changes in global carbon cycle. There is still intense debate about the reasons for this global phenomenon, the basis of which was researched by him. His 1976 publication on this subject (Schidlowski et al., Geochim.Cosmochim. Acta 40: 449-455) is still cited several times in 2012. The move to the Max Planck Institute set the course for Schidlowski's future scientific career: research into the Earth system during the Precambrian. The time in Mainz was interrupted by stays at Harvard University, the University of California Los Angeles and the Weizman Institute in Rehovot, Israel.
From 1979 to 1989, he was chairman of the UNESCO-sponsored IGCP Project 157 (Early Organic Evolution and Mineral and Energy Resources). He established close contacts with geological and geochemical research centres such as the institutes of the Academy of Sciences of the USSR, the Academia Sinica (Lanzhou, Beijing). Since 1996, he was a member of the exobiology science team of the European Space Agency (ESA). He spent his scientific life researching the development of the atmosphere, the ocean and life on the early Earth. He wrote more than 100 scientific papers in journals and book chapters as well as edited special volumes and books on the topic of the early development of the Earth system.
Schidlowski retired in 1998. In 2005 he moved with his wife to Altusried. Here he died on October 3, 2012.
Publications
Manfred Schidlowski: Search for Morphological and Biogeochemical Vestiges of Fossil Life in Extraterrestrial Settings: Utility of Terrestrial Evidence. In: Horneck G., Baumstark-Khan C. (eds) Astrobiology. Springer, Berlin, Heidelberg 2002, pages 373–386.
Pitawala, A., Schidlowski, M., Dahanayake, K. et al.: Geochemical and petrological characteristics of Eppawala phosphate deposits, Sri Lanka. In: Miner Deposita, Vol. 38, September 2002, pages 505–515.
Manfred Schidlowski: Carbon isotopes as biogeochemical recorders of life over 3.8 Ga of Earth history: evolution of a concept. In: Precambrian Research, Vol. 106, Issues 1–2, 1 February 2001, pages 117-134
Yanan Shen, Manfred Schidlowski: New C isotope stratigraphy from southwest China: Implications for the placement of the Precambrian-Cambrian boundary on the Yangtze Platform and global correlations . In: Geology, Vol. 28, Issue 7, 1 July 2000, pages 623–626.
B. Nagy, R. Weber, J.C. Guerrero, M. Schidlowski: Developments and Interactions of the Precambrian Atmosphere, Lithosphere and Biosphere. Latest Edition, 1 April 2000.
Manfred Schidlowski, Stjepko Golubic, Michael M. Kimberley, David M. McKirdy Sr.: Early Organic Evolution - Implications for Mineral and Energy Resources: A Farewell Address to IGCP Project 157. Springer, Berlin, Heidelberg 1992. PDF.
Manfred Schidlowski: A 3,800-million-year isotopic record of life from carbon in sedimentary rocks. In: Nature 333, 26 May 1988, pages 313–318.
Manfred Schildlowski: Antiquity and Evolutionary Status of Bacterial Sulfate Reduction: Sulfur Isotope Evidence. In: Limits of Life, 1980, pages 159–171.
Manfred Schidlowski, Rudolf Eichmann, Christian E. Junge: Precambrian sedimentary carbonates: carbon and oxygen isotope geochemistry and implications for the terrestrial oxygen budget. In: Precambrian Research, Vol 2, Issue 1, February 1975, pages 1-69.
Manfred Schidlowski: Probable Life-forms from the Precambrian of the Witwatersrand System (South Africa). In: Nature, Vol. 205, 27 February 1965, pages 895–896.
References
1933 births
2012 deaths
Geochemists
German academics | Manfred Schidlowski | [
"Chemistry"
] | 1,507 | [
"Geochemists"
] |
69,468,450 | https://en.wikipedia.org/wiki/Astronomicum%20Caesareum | Astronomicum Caesareum (Astronomy of the Caesars; also translated as The Emperor's Astronomy) is a book by Petrus Apianus first published in 1540.
Astronomicum was initially published in 1540. Charles V, Holy Roman Emperor, and his brother Ferdinand I, Holy Roman Emperor, both commissioned the work. It was printed at Apianus's press in Ingolstadt, Bavaria, and took eight years to produce. It expanded and changed when reprinted; the final version has 55 leaves. Apianus evidently changed his plans while producing a single edition. A volvelle in one version of Astronomicum has "an entirely irrelevant base of an astrolabe" underneath, suggesting that he considered creating one and then abandoned the idea.
Twenty-one of its 36 woodcuts are volvelles. Astronomicum volvelles rely on a geocentric model of the universe. However, despite the false science on which they depended, knowledgeable readers could still use them to predict planetary movements. Nicolaus Copernicus published De revolutionibus orbium coelestium shortly after Astronomicum appeared, which began a transition to heliocentrism as the standard astronomical model.
Although other 16th-century books used volvelles, Astronomicum are distinctive because they take precedence over the book's text, as opposed to serving as illustrations. According to Ronald Brashear and Daniel Lewis, Astronomicum is "really a scientific calculating instrument as much as a book".
A 1997 study reported that 111 copies of the book existed. Tycho Brahe bought one copy in 1599 which is in the collection of a library in Gotha, likely .
Notes
Sources
External links
1540 books
Astronomy books | Astronomicum Caesareum | [
"Astronomy"
] | 356 | [
"Astronomy books",
"Works about astronomy"
] |
69,468,681 | https://en.wikipedia.org/wiki/List%20of%20BMX%20bicycle%20manufacturers | List of BMX bicycles is a list of former and current manufacturers of BMX bicycles.
BMX bicycles
A
C
Colony BMX – Australian BMX Bicycle manufacturer
Cortina Cycles is a bicycle frame manufacturer in Santa Barbara, California
CW Racing BMX manufacturer in Orange, California
CYC Stormer BMX bike
D
Devlin Custom Cycles - Australian BMX Bicycle manufacturer
Diamondback was founded as a BMX brand in 1977 by Western States Imports in Newbury Park, California, which sold bikes under the Centurion (bicycle) brand. Became a highly regarded name in BMX.
E
Ellsworth Handcrafted Bicycles is a bicycle manufacturer based in San Diego, CA. Founded by Tony Ellsworth in 1991.
F
G
GHP BMX Frame, fork, bars and seat post manufacturer
GT Bicycles a freestyle BMX bike with pegs.
H
Haro named for Bob Haro it was a freestyle BMX bike with pegs.
J
JMC BMX Chrome Moly BMX frame and forks
K
Kuwahara BMX chrome frame with red wheels.
L
Laguna BMX bike
M
Murray In 1977, again following a youth trend, Murray introduced its BMX model.
N
Next (bicycle company) is an American bicycle brand distributed by Dynacraft BSC.
P
Patterson Racing - chrome molly BMX frames and forks.
R
Race Inc. BMX bicycle frame manufacturer
Redline Bicycles is an American company offering BMX, freestyle, cyclocross, mountain (MTB), and road bicycles
Robinson Pro BMX bike company started by Chuck Robinson.
S
Schwinn introduced the Scrambler in 1975
Skyway BMX frame and fork manufacturer
SE Racing named for Scot Breithaupt (Scot Enterprises) they manufactured the PK Ripper
T
Torker Started in 1977 manufacturing a BMX bike frame. The first Haro bikes were made by Torker.
W
West Coast Cycle produced the brand Cyclepro BMX
See also
List of bicycle brands and manufacturing companies
Advertiser Blitzkrieg
Planet BMX 1999 (Aus) Graffiti project BMX XXX
References
Manufacturers
Lists of brands
Cycling-related lists
Transport lists
Lists of manufacturers | List of BMX bicycle manufacturers | [
"Physics"
] | 433 | [
"Physical systems",
"Transport",
"Transport lists"
] |
69,469,307 | https://en.wikipedia.org/wiki/Phaeoclavulina%20murrillii | Phaeoclavulina murrillii is a coral fungus that is widely distributed in the southeastern United States. It has also been found as far North in the United States as Michigan, and in Spain.
Taxonomy
It was first found in 1904 by William Alphonso Murrill. Originally, it was described as Clavaria murrilli by William Chambers Coker. Later it was moved to Ramaria by Edred John Henry Corner.
Description
Fruit body
The fruit body may be growing singularly or in scattered groups on the ground in humus in broadleaf or mixed broadleaf and conifer forests from June through October. Fruiting has additionally been reported as occurring in low nutrient areas within meadows. The size ranges from 4–12 centimeters high that are coral-like in appearance with many branches and arising from a rounded, central stalk. Much of the lower portion of the fruitbody and the stipe have white threads that stain pinkish, and these threads can be observed on dry specimens too. The branches are rounded and described as a "dull brownish pink to pale rusty brown, darkening when bruised", and are fibrous-tough and twisted and divided. The branch tips can be pointed or blunt, and are white at first, becoming "golden-yellow to orange" and turning more brown with age.
Spore print
The spores have a "dull ochraceous tan" deposit.
Microscopic features
The spores "appear brown under the microscope". The spore size is comparatively more divergent than similar species ranging from 6.5–9.5 × 3.5–5.5 μm, and they are "elliptic to bottle-shaped" or "elongate pip-shaped". The basidia are clavate, 5–5.5 μm wide and 4-spored. The hymenium is 50–60 μm thick. The hyphae are 3.5–5 μm wide and clamp-connections are present.
Chemical test
Applying FeSO4 to the branches will cause them to stain green.
Edibility
The edibility is unknown. It has a nondistinctive odor, and the taste of the flesh is described as bitter.
References
Gomphaceae
Fungi of North America
Fungi of Europe
Fungi described in 1923
Fungus species | Phaeoclavulina murrillii | [
"Biology"
] | 466 | [
"Fungi",
"Fungus species"
] |
69,469,965 | https://en.wikipedia.org/wiki/Murad%20Takla | In Bangladeshi humour and popular culture, Murad Takla () refers to someone who writes Bengali words using the Latin script in a bizarre or unorthodox fashion, which unintentionally produces a distorted meaning. The phrase originated in the 2010s.
History
A Facebook comment posted on 14 July, 2012 was the origin of Murad Takla. In the comment, a commenter told the other commenter to speak with logic. He asked why the person had a lame profile picture, and told him to learn before speaking. The screenshot of the comment went viral on Facebook because of its unintentional humour: The commenter wrote Murad Takla ("Murod thakle" in Banglish) which was intended to mean "if you have courage", but its pronunciation simply means "a bald person named Murad". The phrase became popular and synonymous with those who write distorted Bengali using the Latin script.
After the incident, a Facebook page named Murad Takla was created in 18 November of the same year. The page was created for sharing humorous posts written in Bengali using the Latin script. The page gained popularity, giving some people a greater understanding of the potential problems of writing Bengali with Latin letters.
The term has also been used to refer to Bangladeshi politician Murad Hasan after a controversy over the leak of an obscene phone call. The discussion about Murad Hasan led to some confusion about the term.
Dictionary
In 2020, the Murad Takla Dictionary was published by Simu Nasser and Pian Mughdha Nabi for the purpose of understanding the meaning of sentences written in the "Takla language".
Examples
See also
Romanisation of Bengali
Banglish
Notes and references
Notes
References
External links
Internet terminology
Bengali words and phrases
Internet memes introduced in 2012
Internet memes introduced from Bangladesh
2010s fads and trends | Murad Takla | [
"Technology"
] | 371 | [
"Computing terminology",
"Internet terminology"
] |
69,470,433 | https://en.wikipedia.org/wiki/Surplus%20sharing | Surplus sharing is a kind of a fair division problem where the goal is to share the financial benefits of cooperation (the "economic surplus") among the cooperating agents. As an example, suppose there are several workers such that each worker i, when working alone, can gain some amount ui. When they all cooperate in a joint venture, the total gain is u1+...+un+s, where s>0. This s is called the surplus of cooperation, and the question is: what is a fair way to divide s among the n agents?
When the only available information is the ui, there are two main solutions:
Equal sharing: each agent i gets ui+s/n, that is, each agent gets an equal share of the surplus.
Proportional sharing: each agent i gets ui+(s*ui/Σui), that is, each agent gets a share of the surplus proportional to his external value (similar to the proportional rule in bankruptcy). In other words, ui is considered a measure of the agent's contribution to the joint venture.
Kolm calls the equal sharing "leftist" and the proportional sharing "rightist".
Chun presents a characterization of the proportional rule.
Moulin presents a characterization of the equal and proportional rule together by four axioms (in fact, any three of these axioms are sufficient):
Separability - the division of surplus within any coalition T should depend only on the total amount allocated to T, and on the opportunity costs of agents within T.
No advantageous reallocation - no coalition can benefit from redistributing its ui among its members (this is a kind of strategyproofness axiom).
Additivity - for each agent i, the allocation to i is a linear function of the total surplus s.
Path independence - for each agent i, the allocation to i from surplus s is the same as allocating a part of s, updating the ui, and then allocating the remaining part of s.
Any pair of these axioms characterizes a different family of rules, which can be viewed as a compromise between equal and proportional sharing.
When there is information about the possible gains of sub-coalitions (e.g., it is known how much agents 1,2 can gain when they collaborate in separation from the other agents), other solutions become available, for example, the Shapley value.
See also
Bankruptcy problem - a similar problem in which the goal is to share losses (negative gains).
Cost-sharing mechanism - a similar problem in which the goal is to share costs.
Frederic G. Mather, Both sides of profit sharing: an 1896 article about the need to share the surplus of work fairly between employees and employers.
References
Fair division | Surplus sharing | [
"Mathematics"
] | 564 | [
"Recreational mathematics",
"Game theory",
"Fair division"
] |
69,470,879 | https://en.wikipedia.org/wiki/EU%20Chemicals%20Strategy%20for%20Sustainability%20Towards%20a%20Toxic-Free%20Environment | The EU's Chemicals Strategy for Sustainability Towards a Toxic-Free Environment is a strategy published in 2020 that is part of the EU's zero pollution ambition, a key commitment of the European Green Deal.
See also
Registration, Evaluation, Authorisation and Restriction of Chemicals
References
External links
https://ec.europa.eu/environment/strategy/chemicals-strategy_en
European Union
European Green Deal
Environmental policy in the EU
Chemical safety | EU Chemicals Strategy for Sustainability Towards a Toxic-Free Environment | [
"Chemistry"
] | 89 | [
"Chemical safety",
"Chemical accident",
"nan"
] |
69,471,071 | https://en.wikipedia.org/wiki/Henry%20Rimisho | Henry M. Rimisho (born 1969) is a Tanzanian Architect and Lecturer from the Department of Architecture, School of Architecture, Construction, Economics and Management at Ardhi University in Dar es Salaam. He is also a Missionary priest from the Congregation of The Apostles of Jesus based in Nairobi, Kenya.
Biography
Rimisho was born in Kinondoni, Dar es Salaam in the United Republic of Tanzania, to Mr. and Mrs. Jacob Rimisho. In 1994, he attended Pontifical Urban University for (Bachelor's degree) in Philosophy and 2000 he attained (Bachelor's degree) in Theology. From 2012 he also attained (Bachelor's degree), in 2014 (Master's degree) and 2020 Doctoral (PhD) in Architecture from Ardhi University.
Career
Henry Rimisho is a member of Architects Association of Tanzania and lectures mostly in urban development and housing, architectural design studio, building materials, profession practice, building service and research methodology.
Selected works
External links
References
1969 births
Living people
Tanzanian Roman Catholics
Tanzanian educators
Pontifical Urban University
Tanzanian clergy
Tanzanian Roman Catholic priests
Academic staff of the Ardhi University
Clergy from Dar Es Salaam | Henry Rimisho | [
"Engineering"
] | 241 | [
"Architecture writers",
"Architecture"
] |
69,471,190 | https://en.wikipedia.org/wiki/Tuberculosis%20hut | A tuberculosis hut or TB hut is a small wooden building that was used, mostly in the early twentieth century, by tuberculosis patients to recover in solitude.
Introduction
By the end of the 19th century, one out of four deaths in Europe was related to tuberculosis. The disease was often associated with bad hygiene and air pollution in the cities. As a result of improvements in housing and healthcare in the beginning of the 20th century, there was a downward trend in the number of patients, but there was still no cure. Medical treatment consisted mainly of bedrest, sunlight, fresh air and healthy food. As an alternatives to treatment in a sanatorium, tuberculosis huts were introduced.
Locations
In the United Kingdom and the Netherlands, the houses could be found in groups near hospitals or sanatoria. In the Netherlands, these could also be found near health associations, on farmground just outside the town center or in gardens of individuals. Once a day a nurse visited the patient for medical treatment; the family of the patient took care of the rest. The huts could be bought, borrowed or rented.
In the United States, similar huts were built in Colorado Springs. Where patients in Europe were sent to sanatoria in the Alps, patients in the United States were encouraged to cure in the fresh mountain air of Colorado Springs. Charles Fox Gardiner, a local doctor, decided to avoid any cross-contamination between patients by isolating them in small tents, instead of putting them all in one room. He developed special octahedral huts, that were placed in rows.
Design
Tuberculosis huts existed in various forms, but in general they were simple premanufactured wooden buildings, that could be put together on the spot. They were white or green, with a lot of glass to allow the entering of as much sunlight as possible. On the front side, the houses were either fully open, or they contained large doors that could be opened wide. The huts in Colorado Springs were fixed to one place. The type of huts that was used in British hospitals, could be rotated on turntables towards the sun and out of the wind, to optimise the recovery conditions for the patients. In the Netherlands, both the fixed and the revolving types could be found.
Use
The original purpose of the hut was that the patient could recover by resting in solitude. The patient was supposed to stay in the hut night and day, and this stay could take months or even years. The huts were acquired for other purposes too, like a summerhouse or gazebo. At least the Irish playwright George Bernard Shaw and sexologist Havelock Ellis are known to have owned a revolving "writing hut". Until the late 1940s tuberculosis patients were often put in tuberculosis huts. With the introduction of effective medication in the 1950s the huts lost their original purpose and started to serve new ones. In 1982 the collection of the Netherlands Open Air Museum was expanded with a tuberculosis hut, as a gift from the National Cross Association. One of the open-air TB huts of Montcalm Sanitarium in Manitou Springs, Colorado was donated to the Miramont Castle museum in 1998. Rijksmuseum Boerhaave in Leiden (The Netherlands) owns a hut since 2011 and Open Air Museum Het Hoogeland in Warffum (The Netherlands) owns one since April 2016.
See also
Luftkurort
References
Buildings and structures by type
Tuberculosis | Tuberculosis hut | [
"Engineering"
] | 683 | [
"Buildings and structures by type",
"Architecture"
] |
69,471,775 | https://en.wikipedia.org/wiki/Parmelia%20ambra | Parmelia ambra is a fossilised species of foliose lichen in the family Parmeliaceae. Found in Dominican amber and described as a new species in 2000, the fossil has been used in subsequent studies of lichen evolution.
Taxonomy
The fossil was discovered in Dominican amber and formally described as a new species in 2000 by George Poinar Jr., Eric Peterson, and Jamie Platt. Because of its resemblance to modern-day members of Parmelia, it has been placed provisionally in that genus, although the authors acknowledge that without sacrificing more of the specimen for analysis, it is impossible to assert this definitively.
Based on what types of organisms are used for dating, Dominican amber dates from 15–20 million years ago (based on foraminifera fossils), to 30–45 million years (based on coccolith fossils). Because lichens are scarce in the fossil record, specimens like this are often used as calibration points for molecular clock analyses to improve understanding of lichen evolution.
Description
The fossil lichen has a thallus comprising dichotomously branched lobes with a thickness of 30–50 μm. The upper thallus surface is smooth and lighter in colour than the lower surface, which is black with dark rhizines measuring 0.5–0.9 mm long. Neither apothecia nor pycnidia are apparent on the fossil. A single isidium is present, with a length of 110 μm and diameter of 50 μm. The hyphae of the medulla are thick-walled, loosely interwoven, and have a diameter of 0.8–2.3 μm. Algal cells, rounded to somewhat elliptic in shape and measuring 5.8–11.6 μm, are present at the interface between the cortex and the medulla.
References
ambra
Lichen species
Lichens described in 2000
Lichens of the Caribbean
Prehistoric fungi
Fossil taxa described in 2000
Dominican amber
Taxa named by George Poinar Jr. | Parmelia ambra | [
"Biology"
] | 418 | [
"Fungi",
"Prehistoric fungi"
] |
69,472,087 | https://en.wikipedia.org/wiki/Pyrilutamide | Pyrilutamide (developmental code name KX-826) is a nonsteroidal antiandrogen (NSAA) – specifically, a selective high-affinity silent antagonist of the androgen receptor (AR) – which is under development by Suzhou Kintor Pharmaceuticals, inc., a subsidiary of Kintor Pharmaceutical Limited, for the potential treatment of androgenic alopecia (androgen-dependent scalp hair loss) As of September 2022, it is in phase 3 clinical trials for androgenic alopecia and phase 2 trials for acne.
Development
Pyrilutamide has undergone several clinical trials for the treatment of androgenic alopecia (AGA) in both males and females. The primary endpoint for most trials was the change from baseline in non-vellus target area hair count (TAHC) compared to placebo after 24 weeks of treatment.
Phase II Trials
Male AGA in China
A phase II trial in China enrolled 120 male patients, randomized into four groups: KX-826 0.25% BID (twice daily), KX-826 0.5% QD (once daily), KX-826 0.5% BID, and placebo. After 24 weeks, the 0.5% BID group showed significant improvement:
Non-vellus target area hair count (TAHC) increased by 22.73 hair counts per cm² from baseline (P<0.001)
TAHC increased by 15.34 hair counts per cm² compared to placebo (P=0.024)
Female AGA in China
A phase II trial for female AGA in China included 160 patients in five groups: KX-826 0.25% QD, 0.25% BID, 0.5% QD, 0.5% BID, and placebo. After 24 weeks:
The 0.5% QD group showed an increase of 11.39 hair counts per cm² compared to placebo (P=0.0087)
Efficacy was observed as early as 12 weeks
Male AGA in the U.S.
A phase II trial in the U.S. enrolled 123 male patients, divided into KX-826 0.25% QD, 0.5% QD, 0.5% BID, and placebo groups. Results after 24 weeks showed:
The 0.5% BID group increased by approximately 10 hair counts per cm² from baseline (P=0.0088)
A dose-response relationship was observed across different dosage groups
Phase III Trials
Male AGA in China
A phase III trial for male AGA in China enrolled 740 patients, randomized into KX-826 0.5% BID and placebo groups. Results announced on November 27, 2023, showed:
KX-826 promoted hair growth compared to baseline with statistical significance (P<0.0001)
Improvement in TAHC at all visit points compared to placebo, though without statistical significance
Ongoing Studies
A long-term safety phase III trial for AGA treatment in China, enrolling 271 male and female patients for a 52-week treatment period, focusing on treatment-emerged adverse events (TEAE).
A phase Ib/III clinical trial of KX-826 in combination with minoxidil for male AGA in China, approved by NMPA on February 1, 2024.
Availability as a Cosmetic Product
In addition to its ongoing clinical development, Pyrilutamide has been introduced to the market as a cosmetic anti-hair loss product under the brand name Koshine. This approach allows it to be made available to consumers without the need for full regulatory approval as a medical treatment. Its classification as a cosmetic reflects a strategic decision to facilitate earlier access while formal medical approval is still pending.
Adverse effects
Pyrilutamide is generally well-tolerated. The most common adverse event is contact dermatitis.
Across all trials, KX-826 demonstrated a favorable safety profile:
No serious adverse events (SAE) or adverse drug reactions (ADR) were reported
Most treatment-emerged adverse events (TEAE) were mild and similar to placebo
Low systemic exposure was observed after topical application
Pharmacology
Pharmacodynamics
Pyrilutamide binds to the androgen receptor with a very high affinity with an IC50 of 0.28 nM. Reference drug bicalutamide had an IC50 of 3.1 nM.
References
Dermatologic drugs
Experimental drugs
Fluoroarenes
Hair loss medications
Imidazolidines
Nitriles
Nonsteroidal antiandrogens
Oxazoles
Peripherally selective drugs
Trifluoromethyl compounds
Benzamides | Pyrilutamide | [
"Chemistry"
] | 966 | [
"Nitriles",
"Functional groups"
] |
70,967,049 | https://en.wikipedia.org/wiki/PitchCom | PitchCom is a wireless communication system used in baseball that lets a player request pitches without using visible signals. Major League Baseball (MLB) approved the use of PitchCom before the start of the 2022 season with the intentions of deterring sign stealing and quickening the pace of play.
History
Catchers traditionally request pitches with finger signs, but these can be stolen by a runner on second base and relayed to the batter. When a runner reaches second base, the catcher commonly visits the pitcher to change signs, delaying the game.
The technology used in PitchCom was invented by John Hankins and Craig Filcetti to provide cues at magic shows. Their company asked MLB to consider adopting the technology in 2020. During the 2021 Low-A West season, teams were permitted to try PitchCom. The technology was optional but strongly encouraged, according to a memo sent by the league. After generally positive results in the minor league, and in spring training before the 2022 MLB season, the MLB Players Association approved use of PitchCom for the 2022 season.
During spring training before the 2023 MLB season, MLB allowed pitchers to wear PitchCom wristbands so they could call their own pitches. As spring training ended, MLB allowed pitchers to request pitches on PitchCom during the 2023 regular season.
PitchCom also began to be used in the KBO League from July 2024.
Operation
PitchCom has two functional components: a nine-button keypad that the catcher wears and small wireless receivers, with speakers, that the catcher, the pitcher, and up to three other fielders may wear inside their baseball caps. Each receiver can be programmed to a particular spoken language. When the catcher presses buttons to indicate the type of pitch and the desired location, all receivers speak the instructions in the selected language. All communications are encrypted and teams may opt to replace pitch names such as "fastball" with code words.
During its first season of use in MLB, some players had problems using PitchCom. Early in the 2022 season, New York Yankees pitcher Aroldis Chapman had difficulty hearing PitchCom over the crowd during an appearance at Oriole Park at Camden Yards. "We just might have to turn up our volume a little bit," said Jose Trevino, the Yankees' catcher. Gerrit Cole, another Yankees pitcher, had trouble hearing pitch instructions in his first two starts, including an incident where the instructions were drowned out by a siren sound effect that the Yankee Stadium audio crew plays to energize the crowd. During a game on June 30 against the Houston Astros, Yankees pitcher Luis Severino was trying to fix his malfunctioning PitchCom device when Kyle Tucker, on third base, tried to steal home. Severino, despite the distraction, threw out Tucker at home. On Opening Day, Milwaukee Brewers pitcher Corbin Burnes had problems hearing his PitchCom speaker over the crowd noise at American Family Field. As of April 24, Burnes was the only Brewers pitcher regularly using PitchCom; other pitchers had stopped using it, saying that they were not yet comfortable using the technology with their catchers.
During the 2022 season, in response to complaints, PitchCom was modified to have a higher volume limit and to have an extension tube that put sound closer to the player's ear. Even at the higher maximum volume, during the 2022 MLB postseason, Philadelphia Phillies shortstop Bryson Stott struggled to hear the audio over the crowd noise. During a spring training game before the 2023 season, umpires informed Minnesota Twins manager Rocco Baldelli that Tampa Bay Rays batters and umpires could clearly hear Twins pitcher Kenta Maeda's PitchCom signals because Twins catcher Tony Wolters had his speaker volume turned up to an excessively high level, and because the announced crowd of 2,531 at Tropicana Field was quiet.
Reception
Despite early problems, all 30 MLB clubs had started to use PitchCom in some way during the 2022 season. Catcher Tucker Barnhart of the Detroit Tigers said that the technology would make the Tigers ready for the pitch clock when MLB starts to use it. The Cleveland Guardians' manager Terry Francona and catcher Austin Hedges said that the technology sped up games noticeably. Aaron Boone, manager of the Yankees, credits PitchCom with significant speed-ups in Yankees games during the 2022 season. Through their first 54 games in 2022, the Yankees played 25 games (about 47%) in less than three hours each. In 2021, only about 25% of the Yankees' games finished in three hours or less. Across all MLB teams, the average time of a nine-inning game in 2022 decreased by six minutes from the prior season, which ESPN credited in part to PitchCom.
New York Mets pitcher Max Scherzer used PitchCom for the first time on July 27, 2022, in a game against the Yankees in which he pitched 7 innings without conceding any runs. Scherzer praised PitchCom's functionality, but he told reporters that "it should be illegal," saying that it removes incentives for pitchers to create complex visual sign systems that runners are challenged to decode. "It works," said Scherzer about PitchCom, "but it’s taking away a part of the game." Scherzer's comments drew rebuttals from Seattle Mariners relief pitcher Paul Sewald, who called them "a little naïve" and "a bit hypocritical", and from Minnesota Twins starter Sonny Gray, who observed that teams were able to break down sign sequences during a game.
References
External links
Baseball equipment
Telecommunications equipment
Wireless communication systems
KBO League
Major League Baseball | PitchCom | [
"Technology"
] | 1,152 | [
"Wireless communication systems"
] |
70,967,383 | https://en.wikipedia.org/wiki/Mimetic%20interpolation | In mathematics, mimetic interpolation is a method for interpolating differential forms. In contrast to other interpolation methods, which estimate a field at a location given its values on neighboring points, mimetic interpolation estimates the field's -form given the field's projection on neighboring grid elements. The grid elements can be grid points as well as cell edges or faces, depending on .
Mimetic interpolation is particularly relevant in the context of vector and pseudo-vector fields as the method conserves line integrals and fluxes, respectively.
Interpolation of integrated forms
Let be a differential -form, then mimetic interpolation is the linear combination
where is the interpolation of , and the coefficients represent the strengths of the field on grid element . Depending on , can be a node (), a cell edge (), a cell face () or a cell volume (). In the above, the are the interpolating -forms, which are centered on and decay away from in a way similar to the tent functions. Examples of are the Whitney forms for simplicial meshes in dimensions.
An important advantage of mimetic interpolation over other interpolation methods is that the field strengths are scalars and thus coordinate system invariant.
Interpolating forms
In many cases, it is desirable for the interpolating forms to pick the field's strength on particular grid elements without interference from other . This allows one to assign field values to specific grid elements, which can then be interpolated in-between. A common case is linear interpolation for which the interpolating functions (-forms) are zero on all nodes except on one, where the interpolating function is one. A similar construct can be applied to mimetic interpolation
That is, the integral of is zero on all cell elements, except on where the integral returns one. For this amounts to where is a grid point. For the integral is over edges and hence the integral is zero expect on edge . For the integral is over faces and for over cell volumes.
Conservation properties
Mimetic interpolation respects the properties of differential forms. In particular, Stokes' theorem
is satisfied with denoting the interpolation of . Here, is the exterior derivative, is any manifold of dimensionality and is the boundary of . This confers to mimetic interpolation conservation properties, which are not generally shared by other interpolation methods.
Commutativity between the interpolation operator and the exterior derivative
To be mimetic, the interpolation must satisfy
where is the interpolation operator of a -form, i.e. . In other words, the interpolation operators and the exterior derivatives commute. Note that different interpolation methods are required for each type of form (), . The above equation is all that is needed to satisfy Stokes' theorem for the interpolated form
Other calculus properties derive from the commutativity between interpolation and . For instance, ,
The last step gives zero since when integrated over the boundary .
Projection
The interpolated is often projected onto a target, -dimensional, oriented manifolds ,For the target is a point, for it is a line, for an area, etc.
Applications
Many physical fields can be represented as -forms. When discretizing fields in numerical modeling, each type of -form often acquires its own staggering in accordance with numerical stability requirements, e.g. the need to prevent the checkerboard instability. This led to the development of the exterior finite element and discrete exterior calculus methods, both of which rely on a field discretization that are compatible with the field type.
The table below lists some examples of physical fields, their type, their corresponding form and interpolation method, as well as software that can be leveraged to interpolate, remap or regrid the field:
Example
Consider quadrilateral cells in two dimensions with their node indexed in the counterclockwise direction. Further, let and be the parametric coordinates of each cell (). Then
are the bilinear interpolating forms of in the unit square (). The corresponding edge interpolating forms are
were we assumed the edges to be indexed in counterclockwise direction and with the edges pointing to the east and north. At lowest order, there is only one interpolating form for ,
where is the wedge product.
We can verify that the above interpolating forms satisfy the mimetic conditions and . Take for instance,
where , , and are the field values evaluated at the corners of the quadrilateral in the unit square space. Likewise, we have
with , , being the 1-form projected onto edge . Note that is also known as the pullback. If is the map that parametrizes edge , , , then where the integration is performed in space. Consider for instance edge , then with and denoting the start and points. For a general 1-form , one gets .
References
Interpolation
Differential forms | Mimetic interpolation | [
"Engineering"
] | 1,039 | [
"Tensors",
"Differential forms"
] |
70,967,682 | https://en.wikipedia.org/wiki/Barbara%20S.%20Larsen | Barbara Seliger Larsen is a mass spectrometrist, with a career in instrumentations and applications of mass spectrometry in industry, and served on the board of the American Society for Mass Spectrometry for several terms.
Early life and education
Larsen earned a BS in chemistry from Santa Clara University in 1978, and a PhD in chemistry under the direction of Douglas P. Ridge from University of Delaware in 1983. She completed her post-doctoral research with Catherine Fenselau at Johns Hopkins University.
Career
Larsen worked for more than 35 years at DuPont. In her research in mass spectrometry, she worked with a number of ionization sources, from electrospray ionization, matrix-assisted laser desorption/ionization, solid probe introduction with corona discharge ionization, to laserspray ionization. Her fluorinated polymer extraction method, the Larsen method, is required by the Environmental Protection Agency for consumer safety. She is a consultant at Larsen Scientific Consulting.
She serves on the editorial advisory board of Spectroscopy. She was an editor for the Journal of the American Society for Mass Spectrometry. She served on a number of board positions for the American Society for Mass Spectrometry: treasurer (1992-1994), vice president for programs (2004-2006), president (2006-2008), and past president (2008-2010). She was elected as an American Chemical Society Fellow in 2017.
Honors and awards
2010 American Chemical Society The Delaware Section Award
2015 Dupont Pederson Medal
2016 the Analytical Scientist The Power List 2016 Top 50 most influential women
2020 Eastern Analytical Symposium (EAS) Award for Outstanding Achievements in Mass Spectrometry
Books and book chapters
Books
Fulton G. Kitson; Barbara S. Larsen, Charles N. McEwen (1996) Gas Chromatography and Mass Spectrometry: A Practical Guide Academic Press.
Barbara S. Larsen; Charles N. McEwen (Eds.) (2014) Mass Spectrometry of Biological Materials. 2nd Edition. CRC Press.
Book chapters
Charles N. McEwen; Barbara S. Larsen (1997) Electrospray ionization on quadrupole and magnetic-sector mass spectrometers, in Electrospray ionization mass spectrometry: fundamentals, instrumentation, and applications. Richard B. Cole (Ed.) Wiley. 177–202.
Sarah Trimpin; David E. Clemmer; Barbara S. Larsen (2010) Snapshot, Conformation, and Bulk Fragmentation of Polymeric Architectures using ESI–IMS–MS, in Ion Mobility Spectrometry–Mass Spectrometry: Theory and Applications. CRC Press. 215–235.
References
Mass spectrometrists
Santa Clara University alumni
University of Delaware alumni
DuPont people
Fellows of the American Chemical Society
Year of birth missing (living people)
Living people | Barbara S. Larsen | [
"Physics",
"Chemistry"
] | 588 | [
"Biochemists",
"Mass spectrometry",
"Spectrum (physical sciences)",
"Mass spectrometrists"
] |
70,969,725 | https://en.wikipedia.org/wiki/2022%20South%20Khorasan%20train%20derailment | On 8 June 2022 a train collided with an excavator in South Khorasan province, Iran, leaving 22 people dead and 87 others injured. The incident took place 50 kilometres (30 miles) from Tabas as the train travelled from Mashhad to Yazd.
References
2022 in Iran
Derailments in Iran
Railway accidents in 2022
2022 train derailment
June 2022 events in Asia
Excavators | 2022 South Khorasan train derailment | [
"Technology"
] | 88 | [
"Railway accidents and incidents",
"Rail accident stubs"
] |
70,970,708 | https://en.wikipedia.org/wiki/HD%20125248 | HD 125248 is a binary star system in the equatorial constellation of Virgo. It has the variable star designation CS Virginis, while HD 125248 is the designation from the Henry Draper Catalogue. This system is dimly visible to the naked eye as a point of light with an apparent visual magnitude that ranges from 5.84 down to 5.95. It is located at a distance of approximately 280 light years from the Sun based on parallax measurements, but is drifting closer with a heliocentric radial velocity of −8 km/s.
This star was classified as peculiar with spectral type A0p in the Henry Draper Catalogue, published 1918–1924. This class was based on the strength of a pair of lines of ionized silicon in its stellar spectrum. In 1931, W. W. Morgan discovered that the spectrum of the star varied over a period of several days. In particular, the lines of ionized chromium and europium varied considerably in intensity, ranging from strong to very faint. This variation shares similarities to those of α2 Canum Venaticorum. The two sets of lines vary in the opposite direction from each other, so that the chromium lines were minimum when the europium lines were maximized, and vice versa. In 1947, A. J. Deutsch found a period of 9.295 days for the variation.
H. W. Babcock examined the star using Coudé spectrograms in 1947, finding a general magnetic field with a strength of around at the poles. At the time, that was the strongest magnetic field that had been observed in a star. He noticed that the magnetic field was variable, and it showed the opposite polarity when the lines of europium were at a minimum compared to when they were at the maximum. Subsequent observations showed the period and amplitude of the variation to be stable over time. In 1950, D. W. N. Stibbs first proposed an 'oblique rotator model' to explain the properties of this star, in which its magnetic field is locked at an angle to the axis of rotation.
The star displays radial velocity variations that suggest it is a single-lined spectroscopic binary with a period of 4.4 years and an orbital eccentricity of 0.21. The visible component has a stellar classification of A1p SrCrEu, which indicates this is a magnetic peculiar Ap star with prominent abundance anomalies of strontium, chromium, and europium in its atmosphere. It has double the mass and nearly twice the radius of the Sun. The star is an estimated 234 million years old and is spinning with a rotation rate of 9.3 days. It is radiating 42 times the luminosity of the Sun from its photosphere at an effective temperature of 9,850 K.
This is an Alpha2 Canum Venaticorum variable star with a brightness that is modulated by its rotation. Magnetic Doppler imaging of the star suggests the magnetic field deviates strongly from a simple dipole geometry.
References
Further reading
Ap stars
A-type main-sequence stars
Alpha2 Canum Venaticorum variables
Astrometric binaries
Virgo (constellation)
5355
BD-18 3789
Virginis, 236
125248
069929
Virginis, CS | HD 125248 | [
"Astronomy"
] | 676 | [
"Virgo (constellation)",
"Constellations"
] |
70,970,743 | https://en.wikipedia.org/wiki/List%20of%20carbon%20capture%20and%20storage%20projects | This List of carbon capture and storage projects provides documentation of global, industrial-scale projects for carbon capture and storage. According to the Global CCS Institute, in 2020 some 40 million tons CO2 per year capacity of CCS was in operation with 50 million tons per year in development. The world emits about 38 billion tonnes of CO2 every year, so CCS captured about one thousandth of the 2020 total.
Algeria
In Salah was an operational onshore gas field with CO2 injection. CO2 was separated from produced gas and reinjected into the Krechba geologic formation at a depth of 1,900m. Since 2004, about 3.8 Mt of CO2 has been captured during natural gas extraction and stored. Injection was suspended temporarily in June 2011 due to concerns about the integrity of the seal, potential for fracture and leakage into the caprock, and movement of CO2 outside of the Krechba hydrocarbon lease. Injection has not restarted and no leakage of CO2 was reported during the lifetime of the project
Australia
In the early 2020s the government allocated over A$300 million for CCS both onshore and offshore.
Canada
Canadian governments committed $1.8 billion fund CCS projects over the 2008-2018 period. The main programs are the federal government's Clean Energy Fund, Alberta's Carbon Capture and Storage fund, and the governments of Saskatchewan, British Columbia, and Nova Scotia. Canada works closely with the United States through the U.S.–Canada Clean Energy Dialogue launched by the Obama administration in 2009.
Alberta
Alberta committed $170 million in 2013/2014 – and a total of $1.3 billion over 15 years – to fund two large-scale CCS projects.
The CAN $1.2 billion Alberta Carbon Trunk Line Project (ACTL), pioneered by Enhance Energy, became fully operational in June 2020. It is now the world's largest carbon capture and storage system consisting of a 240 km pipeline that collects CO2 industrial emissions from the Agrium fertilizer plant and North West Sturgeon Refinery in Alberta. The capture is then delivered to the matured Clive oil reservoir for use in EOR (enhanced oil recovery) and permanent storage. At full capacity, it can capture 14.6 million tonnes of CO2 per year. For perspective, that translates into capturing CO2 from 2.6 million cars plus.
The Quest Carbon Capture and Storage Project was developed by Shell Canada for use in the Athabasca Oil Sands Project. It is cited as being the world's first commercial-scale CCS project. Construction began in 2012 and ended in 2015. The capture unit is located at the Scotford Upgrader in Alberta, Canada, where hydrogen is produced to upgrade bitumen from oil sands into synthetic crude oil. The steam methane units that produce the hydrogen emit CO2 as a byproduct. The capture unit captures the CO2 from the steam methane unit using amine absorption technology, and the captured CO2 is then transported to Fort Saskatchewan where it is injected into a porous rock formation called the Basal Cambrian Sands. From 2015 to 2018, the project stored 3 Mt CO2 at a rate of 1 Mtpa.
Entropy, a subsidiary of Advantage Energy runs a sequestration project at Glacier plant near Valhalla, Alberta, storing 0.2 MT of CO2 per year as of 2022.
In 2022, Alberta Energy granted 25 CO2 sequestration evaluation licenses covering a total area of 10 million hectares.
Saskatchewan
Boundary Dam Power Station Unit 3 Project
Boundary Dam Power Station, owned by SaskPower, is a coal fired station originally commissioned in 1959. In 2010, SaskPower committed to retrofitting the lignite-powered Unit 3 with a carbon capture unit. The project was completed in 2014. The retrofit utilized a post-combustion amine absorption technology. The captured CO2 was to be sold to Cenovus to be used for Enhanced Oil Recovery (EOR) in Weyburn field. Any CO2 not used for EOR was planned to be used by the Aquistore project and stored in deep saline aquifers. Many complications kept Unit 3 and this project from operating as much as expected, but between August 2017 – August 2018, Unit 3 was online for 65%/day on average. The project has a nameplate capacity of capture of 1 Mtpa. The other units are to be phased out by 2024. The future of the one retrofitted unit is unclear.
Great Plains Synfuel Plant and Weyburn-Midale Project
The Great Plains Synfuel Plant, owned by Dakota Gas, is a coal gasification operation that produces synthetic natural gas and various petrochemicals from coal. The plant began operation in 1984, while CCS began in 2000. In 2000, Dakota Gas retrofitted the plant and planned to sell the CO2 to Cenovus and Apache Energy, for EOR in the Weyburn and Midale fields in Canada. The Midale fields were injected with 0.4 Mtpa and the Weyburn fields are injected with 2.4 Mtpa for a total injection capacity of 2.8 Mtpa. The Weyburn-Midale Carbon Dioxide Project (or IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project), was conducted there. Injection continued even after the study concluded. Between 2000 and 2018, over 30 Mt CO2 was injected.
China
As of 2019 coal accounted for around 60% of China's energy production. The majority of CO2 emissions come from coal-fired power plants or coal-to-chemical processes (e.g. the production of synthetic ammonia, methanol, fertilizer, natural gas, and CTLs). According to the IEA, around 385 out of China's 900 gigawatts of coal-fired power capacity are near locations suitable for CCS. As of 2017 three CCS facilities are operational or in late stages of construction, drawing CO2 from natural gas processing or petrochemical production. At least eight more facilities are in early planning and development, most of which target power plant emissions, with an injection target of EOR.
China's largest carbon capture and storage plant at Guohua Jinjie coal power station was completed in January 2021. The project is expected to prevent 150,000 tons of carbon dioxide emission annually at a 90% capture rate.
CNPC Jilin Oil Field
China's first carbon capture project was the Jilin oil field in Songyuan, Jilin Province. It started as a pilot EOR project in 2009, and developed into a commercial operation for the China National Petroleum Corporation (CNPC). The final development phase completed in 2018. The source of CO2 is the nearby Changling gas field, from which natural gas with about 22.5% is extracted. After separation at the natural gas processing plant, the CO2 is transported to Jilin via pipeline and injected for a 37% enhancement in oil recovery at the low-permeability oil field. At commercial capacity, the facility currently injects 0.6 Mt CO2 per year, and it has injected a cumulative total of over 1.1 million tonnes over its lifetime.
Sinopec Qilu Petrochemical CCS Project
Sinopec is developing a carbon capture unit whose first phase was to be operational in 2019. The facility is located in Zibo City, Shandong Province, where a fertilizer plant produces CO2 from coal/coke gasification. CO2 is to be captured by cryogenic distillation and will be transported via pipeline to the nearby Shengli oil field for EOR. Construction of the first phase began by 2018, and was expected to capture and inject 0.4 Mt CO2 per year. The Shengli oil field is the destination for CO2.
Yanchang Integrated CCS Project
Yanchang Petroleum is developing carbon capture facilities at two coal-to-chemical plants in Yulin City, Shaanxi Province. The first capture plant is capable of capturing 50,000 tonnes per year and was finished in 2012. Construction on the second plant started in 2014 and was expected to be finished in 2020, with a capacity of 360,000 tonnes per year. This CO2 will be transported to the Ordos Basin, one of China's largest coal, oil, and gas-producing regions with a series of low- and ultra-low permeability oil reservoirs. Lack of water has limited the use of water for EOR, so the CO2 increase production.
Germany
From 2008 until 2014 the Schwarze Pumpe power station, about south of the city of Spremberg, was home to the world's first demonstration CCS coal plant. The mini pilot plant was run by an Alstom-built oxy-fuel boiler and is also equipped with a flue gas cleaning facility to remove fly ash and sulfur dioxide. The Swedish company Vattenfall AB invested some €70 million in the two-year project, which began operation 9 September 2008. The power plant, which is rated at 30 megawatts, was a pilot project to serve as a prototype for future full-scale power plants. 240 tonnes a day of CO2 were being trucked to be injected into an empty gas field. Germany's BUND group called it a "fig leaf". For each tonne of coal burned, 3.6 tonnes of CO2 was produced. The CCS program at Schwarze Pumpe ended in 2014 due to nonviable costs and energy use.
As of 2007, the German utility RWE operated a pilot-scale CO2 scrubber at the lignite-fired Niederaußem power station built in cooperation with BASF (supplier of detergent) and Linde engineering.
Japan
The Tomakomai CCS Demonstration Project is an ongoing project led by Japan CCS Co., Ltd. (JCCS) in Tomakomai, Hokkaido prefecture. Funded by METI and commissioned by NEDO, JCCS has been leading CCS-related researches, including CO2 capture, injection and geological measurements at its Tomakomai site since 2012, although CO2 injection has been concluded since November 22, 2019 after reaching 300,012 tons of injected CO2, slightly above the initially proposed 300,000 tons.
The source of the CO2 was Idemitsu Kosan's nearby oil refinery, which was connected to the Tomakomai CCS site via an 1.4km (0.87mi) pipeline. After amine gas treating a CO2 purity of 99% or higher has been achieved, which was then sent to the injection facility, where it was compressed and then injected into two separate undersea reservoirs. The reservoirs are located in the Lower Quaternary Moebetsu (which consists of sandstone) and the Miocene Takinoue (which consists of volcanic and volclaniclastic rocks) formation, located 1000 to 1200m (3280 to 3940ft) and 2400 to 3000m (7875 to 9840ft) deep respectively. In the future the facility may serve as a trial site for transferring liquefied CO2 from vessels directly into the reservoirs.
After the 2018 Hokkaido Eastern Iburi earthquake, a survey conducted by JCCS revealed that the reservoirs did not sustain any detectable damage, as well as no direct link between the earthquake and the CCS facility could be established.
Netherlands
Developed in the Netherlands, an electrocatalysis by a copper complex helps reduce CO2 to oxalic acid.
Norway
In Norway, the CO2 Technology Centre (TCM) at Mongstad began construction in 2009, and completed in 2012. It includes two capture technology plants (one advanced amine and one chilled ammonia), both capturing flue gas from two sources. This includes a gas-fired power plant and refinery cracker flue gas (similar to coal-fired power plant flue gas).
In addition to this, the Mongstad site was also planned to have a full-scale CCS demonstration plant. The project was delayed to 2014, 2018, and then indefinitely. The project cost rose to US$985 million. Then in October 2011, Aker Solutions' wrote off its investment in Aker Clean Carbon, declaring the carbon sequestration market to be "dead".
On 1 October 2013, Norway asked Gassnova, its Norwegian state enterprise for carbon capture and storage, not to sign any contracts for carbon capture and storage outside Mongstad.
In 2015 Norway was reviewing feasibility studies and hoping to have a full-scale carbon capture demonstration project by 2020.
In 2020, it then announced "Longship" ("Langskip" in Norwegian). This 2,7 billion CCS project will capture and store the carbon emissions of Norcem's cement factory in Brevik. Also, it plans to fund Fortum Oslo's Varme waste incineration facility. Finally, it will fund the transport and storage project "Northern Lights", a joint project between Equinor, Shell and Total. This latter project will transport liquid CO2 from capture facilities to a terminal at Øygarden in Vestland County. From there, CO2 will be pumped through pipelines to a reservoir beneath the seabed. The first two CO2 carrier ships for the Øygarden terminal were under construction at Dalian Shipbuilding in China in 2022. They are being equipped with rotor sails estimated to cut emissions by 5%. Øygarden is the world's first open-access transport and storage infrastructure.
Sleipner CO2 Injection
Sleipner is a fully operational offshore gas field with CO2 injection initiated in 1996. CO2 is separated from produced gas and reinjected in the Utsira saline aquifer (800–1000 m below ocean floor) above the hydrocarbon reservoir zones. This aquifer extends much further north from the Sleipner facility at its southern extreme. The large size of the reservoir accounts for why 600 billion tonnes of CO2 are expected to be stored, long after the Sleipner natural gas project has ended. The Sleipner facility is the first project to inject its captured CO2 into a geological feature for the purpose of storage rather than economically compromising EOR.
United Arab Emirates
After the success of their pilot plant operation in November 2011, the Abu Dhabi National Oil Company and Abu Dhabi Future Energy Company moved to create the first commercial CCS facility in the iron and steel industry. CO2 is a byproduct of the iron making process. It is transported via a 50 km pipeline to Abu Dhabi National Oil Company oil reserves for EOR. The facility's capacity is 800,000 tonnes per year. As of 2013, more than 40% of gas emitted by the crude oil production process is recovered within the oil fields for EOR.
United Kingdom
The government aims to capture and store 20-30 Mtpa by 2030, and over 50 Mtpa by 2035 (for comparison greenhouse gas emissions by the United Kingdom were 425 Mt in 2021). The 2020 budget allocated 800 million pounds to attempt to create CCS clusters by 2030, to capture CO2 from heavy industry and a gas-fired power station and store it under the North Sea. The Crown Estate is responsible for storage rights on the UK continental shelf and it has facilitated work on offshore CO2 storage technical and commercial issues, and the North Sea Transition Authority has awarded 6 undersea storage licences including to BP and Equinor.
A trial of bio-energy with carbon capture and storage (BECCS) at a wood-fired unit in Drax power station in the UK started in 2019. If successful this could remove one tonne per day of CO2 from the atmosphere, and the company aims for operations to start in 2027.
In the UK CCS is under consideration to help with industry and heating decarbonization, and it is hoped that building small modular units to fit to existing factories will lower the cost below the carbon price on the UK Emissions Trading Scheme, which was around 80 GBP per tonne in early 2022. Direct air capture is also still being considered, but as of 2022 is much too expensive.
In May 2022, it was announced that Nuada (formerly MOF Technologies) had partnered with HeidelbergCement, Buzzi Unicem and Cementir Holding to build a point source carbon capture plant to further hard to abate industry decarbonization
United States
In addition to individual carbon capture and sequestration projects, various programs work to research, develop, and deploy CCS technologies on a broad scale. These include the National Energy Technology Laboratory's (NETL) Carbon Sequestration Program, regional carbon sequestration partnerships and the Carbon Sequestration Leadership Forum (CSLF).
In September 2020, the U.S. Department Of Energy awarded $72 million in federal funding to support the development and advancement of carbon capture technologies. Under this cost-shared program, DOE awarded $51 million to nine new projects for coal and natural gas power and industrial sources.
The nine projects were to design initial engineering studies to develop technologies for byproducts at industrial sites. The projects selected are:
Enabling Production of Low Carbon Emissions Steel Through CO2 Capture from Blast Furnace Gases — ArcelorMittal USA
LH CO2MENT Colorado Project — Electricore
Engineering Design of a Polaris Membrane CO2 Capture System at a Cement Plant — Membrane Technology and Research (MTR) Inc.
Engineering Design of a Linde-BASF Advanced Post-Combustion CO2 Capture Technology at a Linde Steam Methane Reforming H2 Plant — Praxair
Initial Engineering and Design for CO2 Capture from Ethanol Facilities — University of North Dakota Energy & Environmental Research Center
Chevron Natural Gas Carbon Capture Technology Testing Project — Chevron USA, Inc.
Engineering-scale Demonstration of Transformational Solvent on NGCC Flue Gas — ION Clean Energy Inc.
Engineering-Scale Test of a Water-Lean Solvent for Post-Combustion Capture — Electric Power Research Institute Inc.
Engineering Scale Design and Testing of Transformational Membrane Technology for CO2 Capture — Gas Technology Institute (GTI)
$21 million was also awarded to 18 projects for technologies that remove CO2 from the atmosphere. The focus was on the development of new materials for use in direct air capture and will also complete field testing. The projects:
Direct Air Capture Using Novel Structured Adsorbents — Electricore
Advanced Integrated Reticular Sorbent-Coated System to Capture CO2 from the Atmosphere — GE Research
MIL-101(Cr)-Amine Sorbents Evaluation Under Realistic Direct Air Capture Conditions — Georgia Tech Research Corporation
Demonstration of a Continuous-Motion Direct Air Capture System — Global Thermostat Operations, LLC
Experimental Demonstration of Alkalinity Concentration Swing for Direct Air Capture of CO2 — Harvard University
High-Performance, Hybrid Polymer Membrane for CO2 Separation from Ambient Air — InnoSense, LLC
Transformational Sorbent Materials for a Substantial Reduction in the Energy Requirement for Direct Air Capture of CO2 — InnoSepra, LLC
A Combined Water and CO2 Direct Air Capture System — IWVC, LLC
TRAPS: Tunable, Rapid-uptake, AminoPolymer Aerogel Sorbent for Direct Air Capture of CO2 — Palo Alto Research Center
Direct Air Capture Using Trapped Small Amines in Hierarchical Nanoporous Capsules on Porous Electrospun Hollow Fibers — Rensselaer Polytechnic Institute
Development of Advanced Solid Sorbents for Direct Air Capture — RTI International
Direct Air Capture Recovery of Energy for CCUS Partnership (DAC RECO2UP) — Southern States Energy Board
Membrane Adsorbents Comprising Self-Assembled Inorganic Nanocages (SINCs) for Super-fast Direct Air Capture Enabled by Passive Cooling — SUNY
Low Regeneration Temperature Sorbents for Direct Air Capture of CO2 — Susteon Inc.
Next Generation Fiber-Encapsulated Nanoscale Hybrid Materials for Direct Air Capture with Selective Water Rejection — The Trustees of Columbia University in the City of New York
Gradient Amine Sorbents for Low Vacuum Swing CO2 Capture at Ambient Temperature — The University of Akron
Electrochemically-Driven CO2 Separation — University of Delaware
Development of Novel Materials for Direct Air Capture of CO2 — University of Kentucky Research Foundation
Kemper Project, MS 2010-2021
The Kemper Project is a gas-fired power plant under construction in Kemper County, Mississippi. It was originally planned as a coal-fired plant. Mississippi Power, a subsidiary of Southern Company, began construction in 2010. Had it become operational as a coal plant, the Kemper Project would have been a first-of-its-kind electricity plant to employ gasification and carbon capture technologies at this scale. The emission target was to reduce CO2 to the same level an equivalent natural gas plant would produce. However, in June 2017 the proponents – Southern Company and Mississippi Power – announced that the plant would only burn natural gas.
Construction was delayed and the scheduled opening was pushed back over two years, while the cost increased to $6.6 billion—three times the original estimate. According to a Sierra Club analysis, Kemper is the most expensive power plant ever built for the watts of electricity it will generate.
In October 2021, the coal gasification portion of the plant was demolished.
Terrell Natural Gas Processing Plant
Opening in 1972, the Terrell plant in Texas, United States was the oldest operating industrial CCS project as of 2017. CO2 is captured during gas processing and transported primarily via the Val Verde pipeline where it is eventually injected at Sharon Ridge oil field and other secondary sinks for use in EOR. The facility captures an average of somewhere between 0.4 and 0.5 million tons of CO2 per annum.
Enid Fertilizer
Beginning in 1982, the facility owned by the Koch Nitrogen company is the second oldest large scale CCS facility still in operation. The CO2 that is captured is a high purity byproduct of nitrogen fertilizer production. The process is made economical by transporting the CO2 to oil fields for EOR.
Shute Creek Gas Processing Facility
7 million metric tonnes of CO2 are recovered annually from ExxonMobil's Shute Creek gas processing plant near La Barge, Wyoming, and transported by pipeline to various oil fields for EOR. Started in 1986, as of 2017 this project had the second largest CO2 capture capacity in the world.
Petra Nova (2017-2020)
The Petra Nova project is a billion dollar endeavor undertaken by NRG Energy and JX Nippon to partially retrofit their jointly owned W.A Parish coal-fired power plant with post-combustion carbon capture. The plant, which is located in Thompsons, Texas (just outside of Houston), entered commercial service in 1977. Carbon capture began on 10 January 2017. The WA Parish unit 8 generates 240 MW and 90% of the CO2 (or 1.4 million tonnes) was captured per year. The CO2 (99% purity) is compressed and piped about 82 miles to West Ranch Oil Field, Texas, for EOR. The field has a capacity of 60 million barrels of oil and has increased its production from 300 barrels per day to 4000 barrels daily. On 1 May 2020, NRG shut down Petra Nova, citing low oil prices during the COVID-19 pandemic. The plant had also reportedly suffered frequent outages and missed its carbon sequestration goal by 17% over its first three years of operation. In 2021 the plant was mothballed.
Illinois Industrial, Decatur IL
the Illinois Industrial Carbon Capture and Storage project in Decatur, Illinois is dedicated to geological CO2 storage. The public-private research project spearheaded by Archer Daniels Midland Co received a 171 million dollar investment from the DOE and over 66 million dollars from the private sector. The CO2 is a byproduct of the fermentation process of corn ethanol production and is stored 7000 feet underground in the Mt. Simon Sandstone saline aquifer. Sequestration began in April 2017 with a carbon capture capacity of 1 Mt/a.
NET Power Demonstration Facility, La Porte TX
, the NET Power Demonstration Facility in La Porte, TX was an oxy-combustion natural gas power plant that operated by the Allam power cycle. The plant was able to reduce its air emissions to zero by producing a near pure stream of CO2. and first fired in May 2018.
Century Plant, TX
, Occidental Petroleum, along with SandRidge Energy, operated a West Texas hydrocarbon gas processing plant and related pipeline infrastructure that provides CO2 for Enhanced Oil Recovery (EOR). With a CO2 capture capacity of 8.4 Mt/a, the Century plant was the largest single industrial source CO2 capture facility in the world.
Developing projects by several countries
ANICA - Advanced Indirectly Heated Carbonate Looping Process
The ANICA Project focused on developing economically feasible carbon capture technology for lime and cement plants, which are responsible for 8% of the total anthropogenic carbon dioxide emissions. In 2019, a consortium of 12 partners from Germany, United Kingdom and Greece began working on integrating indirectly heated carbonate lopping (IHCaL) process in cement and lime production. The project aimed at lowering the energy penalty and CO2 avoidance costs for CO2 capture from lime and cement plants.
Port of Rotterdam CCUS Backbone Initiative
Expected in 2021, the Port of Rotterdam CCUS Backbone Initiative aimed to implement a "backbone" of shared CCS infrastructure for use by businesses located around the Port of Rotterdam in Rotterdam, Netherlands. The project is overseen by the Port of Rotterdam, natural gas company Gasunie, and the EBN. It intends to capture and sequester 2 million tons of CO2 per year and increase this number in future years. Although dependent on the participation of companies, the goal of this project is to greatly reduce the carbon footprint of the industrial sector of the Port of Rotterdam and establish a successful CCS infrastructure in the Netherlands following the recently canceled ROAD project. CO2 captured from local chemical plants and refineries will both be sequestered in the North Sea seabed. The possibility of a CCU initiative has also been considered, in which the captured CO2 will be sold to horticultural firms, who will use it to speed up plant growth, as well as other industrial users.
Climeworks Direct Air Capture Plant and CarbFix2 Project
Climeworks opened the first commercial direct air capture plant in Zürich, Switzerland in 2008. Their process captures CO2 from ambient air using a patented filter, isolates the CO2 at high heat, and transports it to a nearby greenhouse as a fertilizer. The plant is built near a waste recovery facility that provides excess heat to power the plant.
Climeworks is also working with Reykjavik Energy on the CarbFix2 project with EU funding. This project, called "Orca," is located in Hellisheidi, Iceland. It uses direct air capture technology in conjunction with a large geothermal power plant. Once CO2 is captured using Climeworks' filters, it is heated using heat from the geothermal plant and used to carbonate water. The geothermal plant then pumps the carbonated water into underground rock formations where the CO2 reacts with basaltic bedrock and forms carbonate minerals for permanent storage.
OPEN100
The OPEN100 project, launched in 2020 by the Energy Impact Center (EIC), is the world's first open-source blueprint for nuclear power plant deployment. The Energy Impact Center and OPEN100 aim to reverse climate change by 2040 and believe that nuclear power is the only feasible energy source to power CCS without the compromise of releasing new CO2.
This project intends to bring together researchers, designers, scientists, engineers, think tanks, etc. to help compile research and designs that will eventually evolve into a blueprint that is available to the public and can be utilized in the development of future nuclear plants.
Nuada
MOF Technologies have developed Nuada, a modular point source carbon capture technology, which uses metal-organic frameworks (MOFs) to deliver energy-efficient removal at a fraction of the cost of conventional amines. After having been selected by the Global Cement and Concrete Association via their Innovandi Open Challenge, Nuada will partner with HeidelbergCement, Buzzi Unicem and Cementir Holding to build pilot plants in 2022.
References
External links
DOE Fossil Energy Department of Energy programs in CO2 capture and storage
US Department of Energy
Zero Emissions Platform - technical adviser to the EU Commission on the deployment of CCS and CCU
National Assessment of Geologic CO2 Storage Resources: Results United States Geological Survey
MIT Carbon Capture and Sequestration Project Database, until 2016
MIT Carbon Capture and Sequestration private public project
List
Bright green environmentalism
Emissions reduction
Gas technologies | List of carbon capture and storage projects | [
"Chemistry",
"Engineering"
] | 5,866 | [
"Greenhouse gases",
"Geoengineering",
"Carbon capture and storage",
"Emissions reduction"
] |
70,970,778 | https://en.wikipedia.org/wiki/HD%20222806 | HD 222806 (HR 8995) is a suspected astrometric binary in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.74, allowing it to be faintly seen with the naked eye. Parallax measurements place the system at a distance of 565 light years and it is currently receding with a heliocentric radial velocity of .
The visible component has a stellar classification of K1 III, indicating that it is a red giant. At present it has 126% the mass of the Sun, but has expanded to almost 19 times its girth. It radiates at 151 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of , giving it an orange hue. HD 222806 is metal enriched with an iron abundance over twice that of the Sun and is believed to be a member of the young disk population. It spins with a projected rotational velocity lower than .
References
Octans
K-type giants
Astrometric binaries
Octantis, 85
222806
117125
8995
PD-79 1239 | HD 222806 | [
"Astronomy"
] | 225 | [
"Octans",
"Constellations"
] |
70,971,264 | https://en.wikipedia.org/wiki/ProbLog | ProbLog is a probabilistic logic programming language that extends Prolog with probabilities. It minimally extends Prolog by adding the notion of a probabilistic fact, which combines the idea of logical atoms and random variables. Similarly to Prolog, ProbLog can query an atom. While Prolog returns the truth value of the queried atom, ProbLog returns the probability of it being true.
Semantics
A probabilistic fact is a pair with a ground atom and the probability of being true. A rule is defined by an atom , called the head, and a finite set of literals , called the body.
ProbLog programs consist of a set of probabilistic facts and a set of rules . Using the distribution semantics, a probability distribution is defined over the two-valued well-founded models of the atoms in the program. The probability of a model is defined as where the product runs over all the literals in the model . For a query atom the distribution semantics defines a probability for the query
in which the sum runs over all the models where is true.
ProbLog supports multiple tasks:
Probabilistic inference: calculate
Most probable explanation: calculate the most probable model probability
Sampling: generate samples of
Learning from interpretations: learn the probabilities of ProbLog programs from data
Example
ProbLog can for example be used to calculate the probability of getting wet given the probabilities for rain and the probabilities that someone brings an umbrella as follows:
0.4 :: rain(weekday).
0.9 :: rain(weekend).
0.8 :: umbrella_if_rainy(Day).
0.2 :: umbrella_if_dry(Day).
umbrella(Day) :- rain(Day), umbrella_if_rainy(Day).
umbrella(Day) :- \+rain(Day), umbrella_if_dry(Day).
wet(Day) :- rain(Day), \+umbrella(Day).
query(\+wet(weekend)).
The last rule before the query states that someone gets wet if it rains and no umbrella was brought. When ProbLog is asked to solve the "probabilistic inference" task, the query asks for the probability to stay dry on a weekend day. When solving the "most probable explanation" task, ProbLog will return the most likely reason for staying dry, i.e. because it is not raining or because the person has an umbrella.
Implementations
The ProbLog language has been implemented as a YAP Prolog library (ProbLog 1). and as a stand-alone Python framework (ProbLog 2)
The source code of ProbLog 2 is licensed under Apache License, Version 2.0 and available on GitHub. The ProbLog language has also been implemented as part of the cplint probabilistic logic programming package for SWI-Prolog, YAP and XSB.
ProbLog variants
ProbLog has been extended or used as inspiration for several different variants, including:
DeepProbLog extends ProbLog by allowing the probability to be parametrized by a neural network.
DTProblog extends ProbLog with decision theory. The utility of a strategy is defined as the expected reward for its execution in the presence of probabilistic effects.
DC-ProbLog extends ProbLog with distributional facts, meaning that instead of probabilities, a logic atom has a corresponding continuous probability distribution instead.
aProbLog generalizes ProbLog by allowing any commutative semiring instead of just probabilities.
ProbFOIL: given a set of ProbLog facts as a probabilistic relational database, ProbFOIL finds a set of probabilistic rules to predict the facts of one relation based on all other relations.
Related languages
PRISM: Programming in statistical modeling
ICL: Independent Choice Logic
CP-Logic: Language of causal probabilistic events
LPAD: Logic programs with annotated disjunctions
Distributional clauses: A probabilistic logic language for hybrid relational domains
Further reading
ProbLog homepage
ProbLog docs
ProbLog repository
References
Probabilistic software
Programming paradigms
Nondeterministic programming languages
Computational statistics
Python (programming language) scientific libraries
Logic programming languages | ProbLog | [
"Mathematics"
] | 897 | [
"Probabilistic software",
"Computational statistics",
"Computational mathematics",
"Mathematical software"
] |
70,971,331 | https://en.wikipedia.org/wiki/Thain%20Family%20Forest | The Thain Family Forest is a 50-acre (20 ha) section of old-growth forest along the Bronx River in the New York Botanical Garden, for a time known as the Native Forest and historically as the Hemlock Grove. Its heritage dates in part to pre-colonial Lenapehoking. New York City acquired 4,000 acres (~1620 ha) as parkland in 1888, and in 1895 the New York Botanical Garden site was chosen here primarily due to the presence of the forest, which covers about one-fifth of the garden grounds. Founding director Nathaniel Lord Britton described the site as "the most precious natural possession of the city of New York". The canopy is in various zones such as oak, hemlock, beech, sweet gum and mixed. The eastern hemlock, the forest's original namesake, declined in the early 20th century, due to the hemlock woolly adelgid and the elongate hemlock scale. Its 2011 redevelopment was supported by John Thain and Carmen Thain, and included the removal of non-native species as well as the expansion of native ones. Several walking trails traverse the forest. Appointed in 2021, Eliot Nagele serves as the Director of the Thain Family Forest.
References
Geography of the Bronx
New York Botanical Garden
Old-growth forests
Trees of New York City | Thain Family Forest | [
"Biology"
] | 273 | [
"Old-growth forests",
"Ecosystems"
] |
70,974,586 | https://en.wikipedia.org/wiki/Chinese%20opera%20costume | Xifu (), also known as Chinese opera costume in English, are the stage clothes and attire worn in Chinese opera, such as Kunqu, Cantonese opera, Beijing opera, Huangmei opera. Some of these costumes bear some resemblance to the Hanfu system but also show some differences in terms of clothing ornaments and decorations, as well as colour system, and in design and construction. In 2006, the techniques used to produce Beijing opera costumes were included in the national intangible cultural heritage list.
Beijing opera
Beijing opera was created in 1790 during the reign of the Qianlong Emperor in the Qing dynasty; however, the origins of its costumes can be traced back to the 14th century. The costumes were set in the Qing dynasty but its style mainly followed the Ming dynasty's hanfu-style clothing. They also absorbed some characteristics of the clothing style worn in the Song, Yuan, and Qing dynasties. Based on various forms of historical clothing, modifications were made to meet the needs of the play (including the singing and dancing movements of the actors).
Beijing opera costumes tend to be decorated with embroidery and exaggerated decorative patterns; the colours also tend to be bright. These costumes are crucial for the audience to understand the play. These costumes follow a social hierarchy (which includes nobles, the humbly born, civilians, military, official or private citizens); they also feature special ornamental patterns and decorations which are crucial in differentiating social class of the characters. The costumes also allow the audience to distinguish a character's sex. They also use subtle differences to distinguish between loyal and wicked characters. Since the costumes used is the same regardless of seasons, the weather is described in every scene of the play and is indicated by the actors' movements rather than on his clothing.
There are 20 major types of costumes, which include: Mang, an informal robe that is generally used for the emperor, nobles, civil and military officials, etc.; pi; kao (an armor, which is used for soldiers), xuezi. Some costumes were also designed by Mei Lanfang, which include guzhuang and the yuntai zhuang (cloud terrace costume).
Cantonese opera
Most Cantonese opera costumes are derived from the clothing style of the Ming dynasty, except for some which are based on the clothing of the Qing dynasty. When depicting plays that are set in all other dynasties except the Qing dynasty, Ming-style costumes are used. The Qing-style costumes are only used when the plays are set in the Qing dynasty.
The standards which are used to indicate particular roles or characters through the wearing of costumes are not as strict as those in Beijing opera. The costumes are typically specific to a general role and a character type, but they are rarely used to represent a specific character. The clothing can be divided into civil and military where the sleeves indicate if the character is civil or military. Colours are also used to indicate the role and character type.
Cantonese opera costumes include the fan gongzhuang, haiqing,. Water sleeves were rarely used before World War II.
Huangmei opera
Huangmei opera costumes typically use ancient-style garments as most plays are based on Chinese folk tales.
Kunqu
Kunqu opera costumes are also based on the clothing style of the Ming dynasty; however, this historical clothing were modified to turn it into a more elaborate and exaggerated version.
The decorations used on the costumes are simple but they often give information about the character's personality; for example, peonies on the robe of a young man may indicate that he is a playboy. Water sleeves are also used in Kunqu opera to accentuate the actors' dance movements.
Types of xifu
Gallery
See also
Hanfu
Guzhuang
Qizhuang
Chinese opera
Footnotes
References
Notes
Chinese traditional clothing
Chinese opera
Costume design | Chinese opera costume | [
"Engineering"
] | 767 | [
"Costume design",
"Design"
] |
70,975,050 | https://en.wikipedia.org/wiki/Capomycin | Capomycin is an antitumor antibiotic with the molecular formula C35H38O10 which is produced by the bacterium Streptomyces capoamus.
References
Antibiotics
Polyols
Esters
Dienes | Capomycin | [
"Chemistry",
"Biology"
] | 45 | [
"Biotechnology products",
"Esters",
"Functional groups",
"Organic compounds",
"Antibiotics",
"Biocides",
"Organic compound stubs",
"Organic chemistry stubs"
] |
70,975,235 | https://en.wikipedia.org/wiki/Thermotolerance | Thermotolerance is the ability of an organism to survive high temperatures. An organism's natural tolerance of heat is their basal thermotolerance. Meanwhile, acquired thermotolerance is defined as an enhanced level of thermotolerance after exposure to a heat stress.
In plants
Multiple factors contribute to thermotolerance including signaling molecules like abscisic acid, salicylic acid, and pathways like the ethylene signaling pathway and heat stress response pathway.
The various heat stress response pathways enhance thermotolerance. The heat stress response in plants is mediated by heat shock transcription factors (HSF) and is well conserved across eukaryotes. HSFs are essential in plants’ ability to both sense and respond to stress. The HSFs, which are divided into three families (A, B, and C), encode the expression of heat shock proteins (HSP). Past studies have found that transcriptional activators HsfA1 and HsfB1 are the main positive regulators of heat stress response genes in Arabidopsis thaliana. The general pathway to thermotolerance is characterized by sensing of heat stress, activation of HSFs, upregulation of heat response, and return to the non-stressed state.
In 2011, while studying heat stress A. thaliana, Ikeda et al. concluded that the early response is regulated by HsfA1 and the extended response is regulated by HsfA2. They used RT-PCR to analyze the expression of HS-inducible genes of mutant (ectopic and nonfunctional HsfB1) and wild type plants. Plants with mutant HsfB1 had lower acquired thermotolerance, based on both lower expression of heat stress genes and visibly altered phenotypes. With these results they concluded that class A HSFs positively regulated the heat stress response while class B HSFs repressed the expression of HSF genes. Therefore, both were necessary for plants to return to non-stressed conditions and acquired thermotolerance.
In animals
References
Biological concepts | Thermotolerance | [
"Biology"
] | 430 | [
"nan"
] |
76,920,619 | https://en.wikipedia.org/wiki/Ground-based%20interferometric%20gravitational-wave%20search | Ground-based interferometric gravitational-wave search refers to the use of extremely large interferometers built on the ground to passively detect (or "observe") gravitational wave events from throughout the cosmos. Most recorded gravitational wave observations have been made using this technique; the first detection, revealing the merger of two black holes, was made in 2015 by the LIGO sites.
, major detectors are the two LIGO sites in the United States, Virgo in Italy and KAGRA in Japan, which are all part of the second generation of operational detectors. Developing projects include LIGO-India as part of the second generation, and the Einstein Telescope and Cosmic Explorer forming a third generation. Space-borne interferometers such as LISA are also planned, with a similar concept but targeting different kind of sources and using very different technologies.
History
While gravitational waves were first formulated as part of general relativity by Einstein in 1916, there were no real attempts to detect them until the 1960s, when Joseph Weber created the first of so-called "Weber bars". While these proved unable to reach the required sensitivity for detecting gravitational waves, many research groups focused on this topic were created at that time. While a lot of efforts were dedicated to improving the resonant bar design, the idea of using a large interferometer for gravitational wave detection was formulated in the 1970s and began to gain traction in the 1980s, leading to the foundation of LIGO in 1984 and Virgo in 1989.
Most of the current large interferometers started construction in the 1990s and finished in the early 2000s (1999 for LIGO, 2003 for Virgo, 2002 for GEO 600). After a few years of observation and improvements to reach their target sensitivity, it became clear that a detection was unlikely and that further upgrades were required, leading to large projects now labelled as the "second generation of detectors" (Advanced LIGO and Virgo), with important sensitivity gains. This periods also marked the beginning of joint observing periods between the different detectors, which are crucial to confirm the validity of a signal, and sparked collaborations between the different teams.
The second generation upgrades were made during the early 2010s, lasting from 2010 to 2014 for LIGO and 2011 to 2017 for Virgo. In parallel, the KAGRA project was launched in Japan in 2010. In 2015, soon after restarting observations, the two LIGO detectors achieved the first direct observation of gravitational waves. This marked the beginning of the still ongoing series of gravitational wave observation periods, labelled O1 through O5; Virgo joined the observations in 2017, near the end of the O2 period, leading quickly to the first three-detector observation, and a few days later the GW170817 event, which is the only one to date to have been observed both with gravitational waves and electromagnetic radiation. KAGRA was completed in 2020, only observing for brief periods of time due to its low sensitivity up until now.
The O4 observing run is currently ongoing, and expected to last until June 2025. More than 90 confirmed detections have been published; the collaborations now also produce live alerts when signals are detected, with more than 100 significant alerts already emitted during O4.
Principle
In general relativity, a gravitational wave is a space-time perturbation which propagates at the speed of light. It thus slightly curves space-time, which locally changes the light path. Mathematically speaking, if is the amplitude (assumed to be small) of the incoming gravitational wave and the length of the optical cavity in which the light is in circulation, the change of the optical path due to the gravitational wave is given by the formula:with being a geometrical factor which depends on the relative orientation between the cavity and the direction of propagation of the incoming gravitational wave. In other terms, the change in length is proportional to both to the length of the cavity and the amplitude of the gravitational wave.
Interferometer
In a typical configuration, the detector is a Michelson interferometer whose mirrors are suspended. A laser is divided into two beams by a beam splitter tilted by 45 degrees. The two beams propagate in the two perpendicular arms of the interferometer, are reflected by mirrors located at the end of the arms, and recombine on the beam splitter, generating interferences which are detected by a photodiode. An incoming gravitational wave changes the optical path of the laser beams in the arms, which then changes the interference pattern recorded by the photodiode.
This means the various mirrors of the interferometer must be "frozen" in position: when they move, the optical cavity length changes and so does the interference signal read at the instrument output port. The mirror positions relative to a reference and their alignment are monitored accurately in real time with a precision better than the tenth of a nanometre for the lengths; at the level of a few nano radians for the angles. The more sensitive the detector, the narrower its optimal working point. Reaching that working point from an initial configuration in which the various mirrors are moving freely is a control system challenge; a complex series of steps is required to coordinate all the steerable parts of the interferometer. Once the working point is achieved, corrections are continuously applied to keep it in the optimal configuration.
The signal induced by a potential gravitational wave is thus "embedded" in the light intensity variations detected at the interferometer output. Yet, several external causes—globally denoted as noise—change the interference pattern perpetually and significantly. Should nothing be done to remove or mitigate them, the expected physical signals would be buried in noise and would then remain undetectable. The design of detectors like Virgo and LIGO thus requires a detailed inventory of all noise sources which could impact the measurement, allowing a strong and continuing effort to reduce them as much as possible.
Using an interferometer rather than a single optical cavity allows one to significantly enhance the detector's sensitivity to gravitational waves. Indeed, in this configuration based on an interference measurement, the contributions from some experimental noises are strongly reduced: instead of being proportional to the length of the single cavity, they depend in that case on the length difference between the arms (so equal arm length cancels the noise). In addition, the interferometer configuration benefits from the differential effect induced by a gravitational wave in the plane transverse to its direction of propagation: when the length of an optical path changes by a quantity , the perpendicular optical path of the same length changes by (same magnitude but opposite sign). And the interference at the output port of a Michelson interferometer depends on the difference of length between the two arms: the measured effect is hence amplified by a factor of 2 compared to a simple cavity.
The optimal working point of an interferometric detector of gravitational waves is slightly detuned from the "dark fringe", a configuration in which the two laser beams recombined on the beam splitter interfere in a destructive way: almost no light is detected at the output port.
Detectors
LIGO
LIGO is composed of two different detectors, one in Hanford, Washington and one in Livingston, Louisiana (they are thus separated by around 3000 km); the two detectors have very similar design, with 4 km long arms, although there are minor differences between the two. They were part of the first generation of detectors, and were completed in 2002; in 2010, they were shut down for an important set of upgrades, termed "Advanced LIGO", making the improved detector a part of the second generation. These upgrades were finished in early 2015, following which the two detectors made the first detection of gravitational waves.
Virgo
Virgo is a single detector located near Pisa, Italy, with 3 km long arms. It was part of the first generation of detectors, following its completion in 2003; it was shut down in 2011 to prepare for the "Advanced Virgo" second-generation upgrades. The upgrades were completed in 2017, allowing it to join the "O2" run, quickly making the first three-detector detection jointly with LIGO.
KAGRA
KAGRA (formerly known as LCGT) is a single interferometer with 3 km long arms, based in the Kamioka Observatory in Japan, which is part of the second generation of detectors. It was first made operational in 2020, although it has not been able to make a detection yet. Although the base design is similar to LIGO and Virgo, it is built underground and integrates cryogenic mirrors, which is why it has often been referred to as a "2.5 generation detector".
Other detectors
GEO600 was initially designed as a British-German effort to build an interferometer with 3 km long arms; it was later downscaled to 600 m due to funding reasons. It was completed in 2002 and is located near Hanover, Germany. Although it has limited capacities (especially in the lower frequency range), making a detection unlikely, it plays a key role in the gravitational wave network as a testbed for many new technologies.
TAMA 300 (and its predecessor, the prototype TAMA 20) was a Japanese detector with 300 m arms, built at the Mitaka university. It was partly designed as a stepstone for larger detectors (including KAGRA), and operated between 1999 and 2004. It has now been repurposed as a testbed for new technologies. The CLIO detector, with 100 m arms and located in the Kamioka mine, is another test detector, specifically designed to test the cryogenic technology used in KAGRA.
LIGO-Australia is a defunct project which was envisioned to be built on the model of the LIGO detector in Australia, but was finally not funded by the Australian government; the project was later relocated to become LIGO-India.
The Fermilab Holometer, with its 39 m long arms, probes a pretty different range in frequency than other interferometers, aiming for the MHz range.
Future detectors
LIGO-India
LIGO-India is a current project of a single interferometer based in Aundha, India, following a design very similar to LIGO (with support from the LIGO collaboration). It has received approval from the Indian government in 2023, and is planned to be completed around 2030.
Cosmic Explorer
Cosmic Explorer is a project for a third-generation detector, featuring two interferometers with respectively 40 km and 20 km long arms located in two different places in the United States. It relies on a design similar to LIGO, leveraging the experience from the two LIGO detectors, scaled to the much longer arm length. It is currently going through the process of approval by the NSF. If approved, it should be completed by the end of the 2030s.
Einstein Telescope
Einstein Telescope is a European project for a third-generation detector; it is currently planned to use a design with three 10 km arms arranged in an equilateral triangle (effectively acting as 3 interferometers), which would be built underground; it would also use cryogenic mirrors. It is currently planned to be completed around 2035, with construction starting in 2026.
Science case
Ground-based detectors are designed to study gravitational waves from astrophysical sources. By design, they can only detect waves with a frequency ranging from a few Hz to a few thousand of Hz. The main known gravitational-wave emitting systems within this range are: black hole and/or neutron star binary mergers, rotating neutron stars, bursts and supernovae explosions, and even the gravitational wave background generated in the instants following the Big Bang. Moreover, gravitational radiation may also lead to the discovery of unexpected and theoretically predicted exotic objects.
Transient sources
Coalescences of black holes and neutron stars
When two massive and compact objects such as black holes and neutron stars orbit each other in a binary system, they emit gravitational radiation and, therefore, lose energy. Hence, they begin to get closer to each other, increasing the frequency and the amplitude of the gravitational waves; this first phase of the coalescence phenomenon, called the "inspiral", can last for millions of years. This culminates in the merger of the two objects, eventually forming a single compact object (generally a black hole). The part of the waveform corresponding to the merger has the largest amplitude and highest frequency, and can only be modeled by performing numerical relativity simulations of these systems. In the case of black holes, a signal is still emitted during a few seconds after the merger, while the new black hole "settles in"; this signal is known as the "ringdown". Current detectors are only sensitive to the late stages of the coalescence of black hole and neutron star binaries: only the last seconds of the whole process can currently be observed (including the end of the inspiral phase, the merger itself and part of the ringdown). The typical shape of the detectable signal is known as the "chirp", as it resembles the sound emitted by some birds, with a rapid increase in amplitude and frequency. All the gravitational waves signal detected so far originate from black hole or neutron star mergers.
Bursts
Any signal lasting from a few milliseconds to a few seconds is considered a gravitational wave burst.
Supernova explosions—the gravitational collapse of massive stars at the end of their lives—emit gravitational radiation that may be seen by current interferometers. A multi-messenger detection (electromagnetic and gravitational radiation, and neutrinos) would help to better understand the supernova process and the formation of black holes.
Other possible burst candidates include perturbations in neutron stars, black hole encounters, "memory" effects arising from the non-linearity of general relativity or cosmic strings. Some phenomena may also generate "long" bursts (longer than 1 second), like instabilities in a black hole accretion disk, or in newly formed black holes and neutron stars when some of the matter ejected during the supernova falls back towards the compact object.
Continuous sources
The main expected sources of continuous gravitational waves are neutron stars, very compact objects resulting from the collapse of massive stars. In particular, pulsars are special cases of neutron stars that emit light pulses periodically: they can spin up to hundreds of times per second (the fastest spinning pulsar currently known is PSR J1748−2446ad, which spins 716 times per second). Any small deviation from axial symmetry (a tiny "mountain" on the surface) will generate long duration periodic gravitational waves. A number of potential mechanisms have been identified which could generate some "mountains" due to thermal, mechanic, or magnetic effects; accretion may also induce a break in axial symmetry.
Another possible source of continuous waves in the current detection range could be more exotic objects, such as dark matter candidates. Axions rotating around a black hole or binary systems consisting of a primordial low-mass black hole and another compact object have in particular been suggested as potential sources. Some possible types of dark matter may also be detected by the interferometers directly, by interacting with optical elements of the device.
Stochastic background
Several physical phenomena may be the source of a gravitational wave stochastic background, an additional source of noise of astrophysical and/or cosmological origin. It represents a (usually) continuous source of gravitational waves, but unlike other continuous wave sources (like rotating neutron stars), it comes from large regions of the sky instead of a single location.
The cosmic microwave background (CMB) is the earliest signal of the Universe that can be observed in the electromagnetic spectrum. However, cosmological models predict the emission of gravitational waves generated instants after the Big Bang. Because gravitational waves interact very weakly with matter, detecting such background would give more insight in the cosmological evolution of our Universe. In particular, it could provide evidence for inflation, from gravitational waves emitted either by the process of inflation itself (according to some theories) or at the end of inflation; first-order phase transitions may also produce gravitational waves. Primordial black holes, which may form during the early universe, are also a potential source of a stochastic background for that period.
Moreover, current detectors may be able to detect an astrophysical background resulting from the superposition of all faint and distant sources emitting gravitational waves at all times, which would help to study the evolution of astrophysical sources and star formation. The most likely sources to contribute to the astrophysical background are binary neutron stars, binary black holes, or neutron star-black hole binaries. Other possible sources include supernovae and pulsars. It is expected that this type of background will be the first kind to be detected by the current ground interferometers.
Finally, cosmic strings may represent a source of gravitational wave background, whose detection could provide proof that cosmic strings actually exist.
Exotic sources
Non-conventional, alternative models of compact objects have been proposed by physicists. Some examples of these models can be described within general relativity (quark and strange stars, boson and Proca stars, Kerr black holes with scalar and Proca hair), others arise from some approaches to quantum gravity (cosmic strings, fuzzballs, gravastars), or come from alternative theories of gravity (scalarised neutron stars or black holes, wormholes). Theoretically predicted exotic compact objects could now be detected and would help to elucidate the true nature of gravity or discover new forms of matter. Furthermore, completely unexpected phenomena may be observed, unveiling new physics.
Fundamental properties of gravity
Gravitational wave polarization
Gravitational waves are expected to have two "tensor" polarizations, nicknamed "plus" and "cross" due to their effects on a ring of particle (displayed in the figure below). A single gravitational wave is usually a superposition of these two polarizations, depending on the orientation of the source.
In addition, some theories of gravity allow for additional polarizations to exist: the two "vector" polarizations (x and y), and the two "scalar" polarizations ("breathing" and "longitudinal"). Detecting these additional polarizations could provide evidence for physics beyond general relativity.
The polarizations can only be distinguished using several detectors; they could only be properly probed after Virgo was introduced, as the two LIGO detectors are almost co-aligned. They can be measured from compact binary coalescences, but also from the stochastic background and continuous waves. With the combination of the current detectors, it is possible to determine the presence or absence of the additional polarizations, but not their nature; a total of 5 independent detectors would be required to fully separate all the polarizations (except for the longitudinal and breathing polarizations, which cannot be distinguished from each other by current detector designs).
Lensed gravitational waves
General relativity predicts that a gravitational wave should be subject to gravitational lensing, just as light waves are; that is, the trajectory of a gravitational wave will be curved by the presence of a massive object (typically a galaxy or a galaxy cluster) near its path. This can result in an increase in the amplitude of the wave, or even multiple observations of the event at different times, as we currently observe for the light of supernovae. Such events are predicted to be common enough to be detected by the current detectors in the near future. Microlensing effects are also predicted. Detecting a lensed event would allow for a very precise localization, as well as further tests of the speed of gravity and of the polarization.
Cosmological measurements
Gravitational waves also provide a new way to measure some cosmological parameters, and in particular the Hubble constant , which represents the rate of the expansion of the universe and whose value is currently disputed due to conflicting measurement from different methods. The main benefit of this method is that the source luminosity distance measured from the gravitational wave signal does not rely on other measurements or assumptions, as is usually the case. There are two main possibilities for measuring with gravitational waves in current detectors:
Multi-messenger events with both a gravitational wave and an electromagnetic signal can be used, by measuring the source distance with the gravitational wave signal and their recession velocity by identifying the galaxy in which the event took place, and applying Hubble's law.
A statistical treatment can be applied to the observed population of binary black hole mergers (often called "dark sirens" in this context), constraining both their mass distribution and ; an external galaxy catalog can also be added to the analysis to improve the measurement to identify possible hosts for the sources.
Testing general relativity
The measurement of gravitational wave signals offers a unique perspective for testing results from general relativity, as they are produced in environments where the gravitational field is very strong (e.g., near black holes). Such tests may uncover physics beyond general relativity, or possible issues in the models.
These tests include:
Looking for a residual signal in the data after subtracting models of the signal, which may indicate that some of the signal is not correctly modelled by general relativity.
Checking that the signal from a merger satisfies some basic assumptions, such as verifying that the estimated parameters of the system are consistent across the different phases of the signal ("inspiral-merger-ringdown consistency test").
Introducing perturbations in the models for simulating gravitational waves to see if they fit the data.
Investigating possible dispersion (absent in general relativity but not in alternative theories).
Analyzing the remnant of a merger, by measuring the post-merger phase of the signal ("ringdown") which is supposed to be fully determined by the mass and spin of the remnant. Such measurements can be the predictions for the energy lost to gravitational waves during the merger and the nature of the remnant object; some hypothetical objects may also feature "echoes" of the ringdown signal.
Looking for non-standard polarizations (as seen above).
Data analysis
The detection of gravitational waves within the output of the detectors (typically known as the "strain") is a complex process. Currently, most of the data processing is done within the LIGO-Virgo-KAGRA (LVK) collaboration; teams outside of the collaboration also produce results on the data once it is released publicly.
The data from the current detectors is initially only available to LVK members; segments of data around detected events are released at the time of publication of the related paper, and the full data is released after a proprietary period, currently lasting 18 months. During the third observing run (O3), this resulted in two separated data releases (O3a and O3b), corresponding to the first six months and last six months of the run respectively. The data is then available for anyone on the Gravitational Wave Open Science Center (GWOSC) platform.
Transient searches
Event detection pipelines
The various software used for the analysis of gravitational wave signals are usually referred to as "search pipelines", as they often encompass many steps of the data processing. During the O3 run, five different pipelines were used to identify event candidates within the data and collect a list of observations of short-lived ("transient") gravitational waves signals in a catalog publication. Four of them (GstLAL, PyCBC, MBTA, and SPIIR) were dedicated to the detection of compact binary coalescences (CBC, the only type of event detected so far), while the fifth one (cWB) was designed to detect any transient signal. All five pipelines have been used during the run ("online") as part of the low-latency alert system, and after the run ("offline") to reassess the significance of the candidates and spot events which may have been missed (except for SPIIR, which was only run online) The oLIB pipeline, also looking for generic "burst" signals, has also been used to generate alerts, but not for the catalogs. In addition, two other pipelines have been used specifically for burst searches after the run, as they are too computationally expensive to be run online : BayesWave, a pipeline using Bayesian techniques which was used to further investigate events by cWB, and STAMPS-AS, which is designed to look specifically for long-duration bursts (more than 1 second).
The four CBC pipelines all rely on the concept of matched filtering, a technique used to search for a known signal within noisy data in an optimal way. This technique requires some knowledge of what the signal looks like, and is thus dependent on the model used to simulate it. Although reasonable models exist, the complexity of the equations governing the dynamics of a compact merger makes the generation of accurate waveforms challenging; the development of new waveforms is still an active field of research. In addition, the sources cover a wide range of possible parameters (masses and spins of the two objects, location in the sky) which will yield different waveforms, instead of having one specific signal. This prompts the researchers to generate "template banks" containing a large amount of different waveforms corresponding to different parameters; a compromise has to be done between how tight the bank is (maximizing the number of detections) and the limited computational resources available to carry out the search with all the templates. How to generate such template banks efficiently is also an active field of research. During the search, the matched filtering is performed on every waveform within the (pre-calculated) template bank.
Although the four searches use the same technique, they all have different optimizations and specificities on how they handle the data. In particular, they use different techniques for estimating the significance of an event, for discriminating between real events and glitches, and for combining the data from the different detectors; they also use different template banks.
The cWB (coherent wave burst) pipeline uses a different approach: it works by grouping the data from the different detectors and carrying a joint analysis to look for coherent signals appearing in several detectors at once. Although its sensitivity for binary mergers is less than the dedicated CBC pipelines, its strength lies in being able to detect signals from any kind of sources, as it does not require any assumption on the shape of the signal (which is why it often referred to as an "unmodeled" search).
Low-latency
The low-latency system is designed to produce alerts for astronomers when gravitational events are detected, with the hope that an electromagnetic counterpart can be observed. This is achieved by centralizing the event candidates from the different analysis pipelines in the gravitational-wave candidate event database (GraceDB), from which the data is processed. If an event is deemed significant enough, a rapid sky localization is produced and preliminary alerts are sent autonomously within the span of a few minutes; after a more precise evaluation of the source parameters, as well as human vetting, a new alert or a retraction notice is sent within a day. The alerts are sent through the GCN, which also centralizes alerts from gamma-ray and neutrino telescopes, as well as SciMMA. A total of 78 alerts were sent during the O3 run, of which 23 were later retracted.
Parameter estimation
After an event has been detected by one of the event detection pipelines, a deeper analysis is performed to get a more precise estimation of the parameters of the source and the measurement uncertainty. During the O3 run, this was carried out using several different pipelines, including Bilby and RIFT. These pipelines employ Bayesian methods to quantify the uncertainty, including MCMC and nested sampling.
Search for counterparts
While many astronomers try to follow-up the low-latency alerts from gravitational wave detectors, the reverse also exists: electromagnetic events expected to have an associated gravitational wave emission are subjected to a deeper search. One of the prime targets for these are gamma-ray bursts; these are thought to be associated with supernovae ("long" bursts, lasting more than 2 seconds) and with compact binary coalescences involving neutron stars ("short" bursts). The merger of two neutron stars in particular has been confirmed to be associated with both a gamma-ray burst and gravitational waves with the GW170817 event.
Searches targeted toward gamma-ray bursts observations have been performed on data from the past runs using the pyGRB pipeline for CBC, using methods similar to the regular searches, but centered around the time of the bursts and targeting only the sky area found by gamma-ray observatories. An unmodelled search was also carried out using the X-pipeline package, in a similar fashion as regular unmodelled searches.
In addition to these searches, several pipelines are looking for coincidences between alerts from gravitational waves and alerts from other detectors. In particular, the RAVEN pipeline is part of the low-latency infrastructure and analyzes the coincidence with gamma-ray burst events and other sources. The LLAMA pipeline is also dedicated to identifying such coincidences with neutrino events, predominantly from IceCube.
Continuous wave searches
Searches dedicated to periodic gravitational waves—such as the ones generated by rapidly rotating neutron stars—are generally referred to as continuous wave searches. These can be divided in three categories: all-sky searches, which look for unknown signals from any direction, directed searches, which aim for objects with known positions but unknown frequency, and targeted searches, which hunt for signals from sources where both the position and the frequency are known. The directed and targeted searches are motivated by the fact that all-sky searches are extremely computationally expensive, and thus require trade-offs that limit their sensitivity.
The principal challenge in continuous wave search is that the signal is much weaker than current detected transients, meaning that one must observe a long time period to accumulate enough data to detect it, as the signal-to-noise ratio scales with the square root of the observing time (intuitively, the signal will add up over the observing duration while the noise will not). The issue is that over such long periods of time, the frequency from the source will evolve, and the motion of the Earth around the Sun will affect the frequency via the Doppler effect. This greatly increases the computational cost of the search, even more so when the frequency is unknown. Although there are mitigation strategies, such as semi-coherent searches, where the analysis is performed separately on segments from the data rather than the full data, these result in a loss of sensitivity. Other approaches include cross-correlation, inspired by stochastic wave searches, which takes advantage of having multiple detectors to look for a correlated signal in a pair of detectors.
Stochastic wave searches
The stochastic gravitational wave background is another target for data analysis teams. By definition, it can be seen as a source of noise in the detectors; the main challenge is to separate it from the other sources of noise, and measure its power spectral density. The easiest method for solving this issue is to look for correlations within a network of several detectors; the idea being that the noise related to the gravitational wave background will be identical in all detectors, while the instrumental noise will (in principle) not be correlated across the detectors. Another possible approach would be to look for excess power not accounted by other noise sources; however, this proves impractical for current interferometers as the noise is not known well enough compared to the expected power of the stochastic background. Only searches based on cross-correlation between detectors are currently in use by the LVK collaboration, although other types of searches are also developed.
This kind of search must also account for factors such as the detectors antenna pattern, the motion of the Earth, and the distance between the detectors. Assumptions also have to be made on some properties of the background; it is common to assume that it is Gaussian and isotropic, but searches for anisotropic, non-Gaussian, and more exotic backgrounds also exist.
Gravitational wave properties searches
A number of software have been developed to investigate the physics surrounding gravitational waves. These analyses are generally performed offline (after the run), and often rely on the results from the other searches (currently mostly CBC searches).
Several analyses are performed to look for events observed multiple time due to lensing, first by trying to match all the known events together, and then by performing a joint analysis for the most promising pair of events; these analyses have been performed using LALInference and HANABI software. Additional searches for events which may have been missed by the regular CBC searches are also performed, by reusing the existing CBC pipelines.
Software designed for estimating the Hubble constant has also been developed. The gwcosmo pipeline performs a Bayesian analysis to determine a distribution of the possible values of the constant, both using "dark sirens" (CBC events without electromagnetic counterpart), which can be correlated with a galaxy catalog, and events with an electromagnetic counterpart for which a direct estimation can be made based on the distance measured with gravitational waves and the identified host galaxy. This requires assuming a specific population of black holes, which may be a significant source of bias; recent analyses have been trying to circumvent this issue by fitting both the population and the Hubble constant simultaneously.
References
Interferometric gravitational-wave instruments
Gravitational-wave astronomy | Ground-based interferometric gravitational-wave search | [
"Physics",
"Astronomy"
] | 6,811 | [
"Astronomical sub-disciplines",
"Gravitational-wave astronomy",
"Astrophysics"
] |
76,924,010 | https://en.wikipedia.org/wiki/4C%2B55.16 | 4C+55.16 is an elliptical galaxy, classified type E, located in Ursa Major. The galaxy lies about 2.84 billion light-years from Earth, which means given its apparent dimensions, 4C+55.16 is approximately 445,000 light-years across making it a type-cD galaxy. It is the brightest cluster galaxy (BCG) in a cluster of the same name.
Characteristics
4C+55.16 has an active nucleus. It is classified as a Fanaroff-Riley Class I or FR-I radio galaxy producing a radio jet. 4C+55.16 contains a radio source, compact and powerful (1.1×1026 W Hz−1 sr−1 at 5 GHz) unlike two other radio galaxies, 3C 295 and Cygnus A. It is classified as a LINER galaxy.
A further study of 4C+55.16
4C+55.16 is located in the center of a cool core of galaxies. The galaxy is radio powerful (LR = 8 Jy/beam at 1.4GHz), and showing signs of interaction with its surrounding intracluster medium (ICM). The hot ICM (T = 107 − 108 K) emits a strong X-ray emission through thermal bremsstrahlung, which cools this medium and causes it to sink down the gravitational well in the form cooling flows. As this accretes into 4C+55.16, the AGN in the center is fed, triggering its central supermassive black hole to produce large quantities of energy in radiation form and strong jetted outflows.
As cooling flow is injected, it completes the feedback cycle preventing a runaway cooling event. The jetted outflows then expands into large lobes against its internal pressure with the ICM. This process can be observed through the radio regime of electromagnetic spectrum, showing magnetized plasma emitted by the black hole or by X-ray radiation, which the lobes appear as cavities in the ICM like Cygnus A and NGC 1275. It is possible that the galaxy is optically disturbed by its companion, with a separation of 81 kpc.
Through combined deep Chandra images (100 ks) and 1.4 GHz Very Large Array observations, researchers were able to find evidence of multiple outbursts originating from its central core. This provides enough energy to offset the cooling process of the ICM (Pbubbles = 6.7 × 1044 erg/s).
Another study shows 4C+55.16 has an unusual intracluster iron distribution. From the 10 ks Chandra exposure, a study from Iwasawa et. al (2001), found that there was a large increase of metallicity which was at a radius of around 10 arcsec, going from half-solar to twice solar. This might be suggested by the plume-like structure which is located south-west side of the cluster.
Further studies showed that the X-ray spectrum of the plume is characterized by its metal abundance pattern of Type Ia supernovae, large ratios of Fe to α elements, with its iron metallicity highest at 7.9 solar (90 per cent error). How the plume formed isn't clear.
Not to mention, 4C+55.16 has two X-ray cavities found on opposite sides of the radio core, discovered by Hlavacek-Larrondo et al. (2011). Such of these meant, is a key tracer of mechanical heating caused by its active galactic nucleus (AGN). The power generated by the AGN in 4C+ 55.16 has remained unchanged for over the half of the age of the universe (>Gyr at z ~ 0.8). Moreover, the detected X-ray cavities have powers of (0.8 - 5) x 10 erg and radii of ~ 17 kpc.
There is a surface brightness edge which is interpreted as cold fronts that are located south of the galaxy's center. A pair of radio lobes is also revealed in the southeast-northwest direction, coinciding with the X-ray cavities. On the VLBA scale, there is a resolved extended emission, well fitted by its two components consisting of a core and a jet. This is consistent with the images published by the European VLBI Network at 5 GHz, published by Whyborn et al. (1985). The northwest cavity is aligned with its radio jet, while the other is misaligned, hence important to note the importance of projection effects in the system where Ψ∥LOS ~ 60°.
The gas pressure at the center of a cooling flow for 4C+55.16, is P=nT≈107 cm−3 K. Through a cloud of length 10l1 pc at pressure 107P7 cm−3 K and temperature 104T4 K, it leads to a free-free absorption optical depth τff≈0.6P27ν9−2T47/2l1 at a frequency 109ν9 Hz. It is plausible it is due to absorption in the Hα emitting gas, close to the nucleus.
References
Ursa Major
Elliptical galaxies
Radio galaxies
Principal Galaxies Catalogue objects
4C objects
Active galaxies
LINER galaxies | 4C+55.16 | [
"Astronomy"
] | 1,080 | [
"Ursa Major",
"Constellations"
] |
76,925,570 | https://en.wikipedia.org/wiki/Fonteferrea | Fonteferrea is a genus of araneoid spiders that contains only one species, Fonteferrea minutissima. It is the sole member of the family Fonteferridae. The original author spelt the family name Fonteferridae. , the World Spider Catalog spelt it Fonteferreidae. The only specimen of this family was found in the Algarve in southern Portugal by Jörg Wunderlich in 2023. The generic name references the locality where the holotype was collected, Fonte Ferrea, in the Faro District. They are extremely small spiders, with a body length of 0.75 mm. The species is notable for the hairs present on the tegulum, a characteristic which very few spiders have.
References
Araneomorphae
Araneomorphae genera
Spiders of Europe
Fauna of Portugal
Species described in the 21st century
Monotypic Araneomorphae genera | Fonteferrea | [
"Biology"
] | 190 | [
"Species described in the 21st century",
"Species by year of formal description"
] |
76,926,283 | https://en.wikipedia.org/wiki/GUN%20%28graph%20database%29 | GUN (Graph Universe Node) is an open source, offline-first, real-time, decentralized, graph database written in JavaScript for the web browser.
The database is implemented as a peer-to-peer network distributed across "Browser Peers" and optional "Runtime Peers". It employs multi-master replication with a custom commutative replicated data type (CRDT).
GUN is currently used in the decentralized version of the Internet Archive.
References
External links
Official website
Graph databases
Database engines
Peer-to-peer computing
Mesh networking
Distributed computing architecture | GUN (graph database) | [
"Mathematics",
"Technology"
] | 119 | [
"Wireless networking",
"Graph theory",
"Mathematical relations",
"Graph databases",
"Mesh networking"
] |
76,927,727 | https://en.wikipedia.org/wiki/M%C3%B3nica%20Morales%20Masis | Mónica Morales Masis (born 1982) is a Costa Rican physicist and materials scientist who works in The Netherlands as a professor at the University of Twente. Her research focuses on optoelectronics, transparent electronics, and solar cells.
Education and career
Morales is originally from Cartago, Costa Rica, where she was born in 1982. A childhood idol was Costa Rican astronaut Franklin Chang-Díaz. After a 2004 bachelor's degree in physics from the University of Costa Rica, she traveled to the US for a master's degree at Wright State University, in 2007, and then to The Netherlands for a doctorate at Leiden University, focusing on condensed-matter physics. Her 2012 doctoral thesis concerned the memristive properties of silver sulfide, and was promoted by Jan van Ruitenbeek; it also included work done at the National Institute for Materials Science in Japan with Tsuyoshi Hasegawa.
Next, she went to Switzerland for postdoctoral research at the École Polytechnique Fédérale de Lausanne (EPFL). Her interest in photovoltaics developed at that time, and she continued at EPFL as a research group leader in the subject. She took a tenure-track faculty position at the University of Twente in 2018, and became a full professor there. At Twente, she is affiliated with the faculty of science and technology, in the inorganic materials science group, and with the MESA+ Institute for Nanotechnology.
Recognition
Morales joined the Young Academy of Europe in 2022.
References
External links
M3 Lab: Optoelectronic materials, directed by Morales
Mónica Morales Masis, Ph.D. (interview in Spanish), ticotal, Academia Nacional de Ciencias de Costa Rica
1982 births
Living people
Costa Rican physicists
Costa Rican women physicists
Materials scientists and engineers
Women materials scientists and engineers
University of Costa Rica alumni
Wright State University alumni
Leiden University alumni
Academic staff of the University of Twente | Mónica Morales Masis | [
"Materials_science",
"Technology",
"Engineering"
] | 399 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology",
"Materials science"
] |
76,928,066 | https://en.wikipedia.org/wiki/Cytochrome%20P450%20%28individual%20enzymes%29 | In biochemistry, cytochrome P450 enzymes have been identified in all kingdoms of life: animals, plants, fungi, protists, bacteria, and archaea, as well as in viruses. , more than 300,000 distinct CYP proteins are known.
P450s in humans
Human P450s are primarily membrane-associated proteins located either in the inner membrane of mitochondria or in the endoplasmic reticulum of cells. P450s metabolize thousands of endogenous and exogenous chemicals. Some P450s metabolize only one (or a very few) substrates, such as CYP19 (aromatase), while others may metabolize multiple substrates. Both of these characteristics account for medicinal interest. Cytochrome P450 enzymes play roles in hormone synthesis and breakdown (including estrogen and testosterone synthesis and metabolism), cholesterol synthesis, and vitamin D metabolism. Cytochrome P450 enzymes also function to metabolize potentially toxic compounds, including drugs and products of endogenous metabolism such as bilirubin, principally in the liver.
The Human Genome Project has identified 57 human genes coding for the various cytochrome P450 enzymes.
Drug metabolism
P450s are the major enzymes involved in drug metabolism, accounting for about 75% of the total metabolism. Most drugs undergo deactivation by P450s, either directly or by facilitated excretion from the body. However, many substances are bioactivated by P450s to form their active compounds like the antiplatelet drug clopidogrel and the opiate codeine.
The CYP450 enzyme superfamily comprises 57 active subsets, with seven playing roles in the metabolism of most pharmaceuticals. The fluctuation in the amount of CYP450 enzymes (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5) in phase 1 (detoxification) can have varying effects on individuals, as genetic expression varies from person to person. This variation is due to the enzyme's genetic polymorphism, which leads to variability in its function and expression. To optimize drug metabolism in individuals, genetic testing should be conducted to determine functional foods and specific phytonutrients that cater to the individual's CYP450 polymorphism. Understanding these genetic variations can help personalize drug therapies for improved effectiveness and reduced adverse reactions.
Drug interaction
Many drugs may increase or decrease the activity of various P450 isozymes either by inducing the biosynthesis of an isozyme (enzyme induction) or by directly inhibiting the activity of the P450 (enzyme inhibition). A classical example includes anti-epileptic drugs, such as phenytoin, which induces CYP1A2, CYP2C9, CYP2C19, and CYP3A4.
Effects on P450 isozyme activity are a major source of adverse drug interactions, since changes in P450 enzyme activity may affect the metabolism and clearance of various drugs. For example, if one drug inhibits the P450-mediated metabolism of another drug, the second drug may accumulate within the body to toxic levels. Hence, these drug interactions may necessitate dosage adjustments or choosing drugs that do not interact with the P450 system.
Many substrates for CYP3A4 are drugs with a narrow therapeutic index, such as amiodarone or carbamazepine. Because these drugs are metabolized by CYP3A4, the mean plasma levels of these drugs may increase because of enzyme inhibition or decrease because of enzyme induction.
Interaction of other substances
Naturally occurring compounds may also induce or inhibit P450 activity. For example, bioactive compounds found in grapefruit juice and some other fruit juices, including bergamottin, dihydroxybergamottin, and paradicin-A, have been found to inhibit CYP3A4-mediated metabolism of certain medications, leading to increased bioavailability and, thus, the strong possibility of overdosing. Because of this risk, avoiding grapefruit juice and fresh grapefruits entirely while on drugs is usually advised.
Other examples:
Saint-John's wort, a common herbal remedy induces CYP3A4, but also inhibits CYP1A1, CYP1B1.
Tobacco smoking induces CYP1A2 (example CYP1A2 substrates are clozapine, olanzapine, and fluvoxamine)
At relatively high concentrations, starfruit juice has also been shown to inhibit CYP2A6 and other P450s. Watercress is also a known inhibitor of the cytochrome P450 CYP2E1, which may result in altered drug metabolism for individuals on certain medications (e.g., chlorzoxazone).
Tributyltin inhibits cytochrome P450, leading to masculinization of mollusks.
Goldenseal, with its two notable alkaloids berberine and hydrastine, has been shown to alter P450-marker enzymatic activities (involving CYP2C9, CYP2D6, and CYP3A4).
Other specific P450 functions
Steroid hormones
A subset of cytochrome P450 enzymes play roles in the synthesis of steroid hormones (steroidogenesis) by the adrenals, gonads, and peripheral tissue:
CYP11A1 (also known as P450scc or P450c11a1) in adrenal mitochondria affects "the activity formerly known as 20,22-desmolase" (steroid 20α-hydroxylase, steroid 22-hydroxylase, cholesterol side-chain scission).
CYP11B1 (encoding the protein P450c11β) found in the inner mitochondrial membrane of adrenal cortex has steroid 11β-hydroxylase, steroid 18-hydroxylase, and steroid 18-methyloxidase activities.
CYP11B2 (encoding the protein P450c11AS), found only in the mitochondria of the adrenal zona glomerulosa, has steroid 11β-hydroxylase, steroid 18-hydroxylase, and steroid 18-methyloxidase activities.
CYP17A1, in endoplasmic reticulum of adrenal cortex has steroid 17α-hydroxylase and 17,20-lyase activities.
CYP21A2 (P450c21) in adrenal cortex conducts 21-hydroxylase activity.
CYP19A (P450arom, aromatase) in endoplasmic reticulum of gonads, brain, adipose tissue, and elsewhere catalyzes aromatization of androgens to estrogens.
Polyunsaturated fatty acids and eicosanoids
Certain cytochrome P450 enzymes are critical in metabolizing polyunsaturated fatty acids (PUFAs) to biologically active, intercellular cell signaling molecules (eicosanoids) and/or metabolize biologically active metabolites of the PUFA to less active or inactive products. These CYPs possess cytochrome P450 omega hydroxylase and/or epoxygenase enzyme activity.
CYP1A1, CYP1A2, and CYP2E1 metabolize endogenous PUFAs to signaling molecules: they metabolize arachidonic acid (i.e. AA) to 19-hydroxyeicosatetraenoic acid (i.e. 19-HETE; see 20-hydroxyeicosatetraenoic acid); eicosapentaenoic acid (i.e. EPA) to epoxyeicosatetraenoic acids (i.e. EEQs); and docosahexaenoic acid (i.e. DHA) to epoxydocosapentaenoic acids (i.e. EDPs).
CYP2C8, CYP2C9, CYP2C18, CYP2C19, and CYP2J2 metabolize endogenous PUFAs to signaling molecules: they metabolize AA to epoxyeicosatetraenoic acids (i.e. EETs); EPA to EEQs; and DHA to EDPs.
CYP2S1 metabolizes PUFA to signaling molecules: it metabolizes AA to EETs and EPA to EEQs.
CYP3A4 metabolizes AA to EET signaling molecules.
CYP4A11 metabolizes endogenous PUFAs to signaling molecules: it metabolizes AA to 20-HETE and EETs; it also hydroxylates DHA to 22-hydroxy-DHA (i.e. 12-HDHA).
CYP4F2, CYP4F3A, and CYP4F3B (see CYP4F3 for latter two CYPs) metabolize PUFAs to signaling molecules: they metabolize AA to 20-HETE. They also metabolize EPA to 19-hydroxyeicosapentaenoic acid (19-HEPE) and 20-hydroxyeicosapentaenoic acid (20-HEPE) as well as metabolize DHA to 22-HDA. They also inactivate or reduce the activity of signaling molecules: they metabolize leukotriene B4 (LTB4) to 20-hydroxy-LTB4, 5-hydroxyeicosatetraenoic acid (5-HETE) to 5,20-diHETE, 5-oxo-eicosatetraenoic acid (5-oxo-ETE) to 5-oxo-20-hydroxy-ETE, 12-hydroxyeicosatetraenoic acid (12-HETE) to 12,20-diHETE, EETs to 20-hydroxy-EETs, and lipoxins to 20-hydroxy products.
CYP4F8 and CYP4F12 metabolize PUFAs to signaling molecules: they metabolizes EPA to EEQs and DHA to EDPs. They also metabolize AA to 18-hydroxyeicosatetraenoic acid (18-HETE) and 19-HETE.
CYP4F11 inactivates or reduces the activity of signaling molecules: it metabolizes LTB4 to 20-hydroxy-LTB4, (5-HETE) to 5,20-diHETE, (5-oxo-ETE) to 5-oxo-20-hydroxy-ETE, (12-HETE) to 12,20-diHETE, (15-HETE) to 15,20-diHETE, EETs to 20-hydroxy-EETs, and lipoxins to 20-hydroxy products.
CYP4F22 ω-hydroxylates extremely long "very long chain fatty acids", i.e. fatty acids that are 28 or more carbons long. The ω-hydroxylation of these special fatty acids is critical to creating and maintaining the skin's water barrier function; autosomal recessive inactivating mutations of CYP4F22 are associated with the lamellar ichthyosis subtype of congenital ichthyosiform erythroderma in humans.
CYP families in humans
Humans have 57 genes and more than 59 pseudogenes divided among 18 families of cytochrome P450 genes and 43 subfamilies. This is a summary of the genes and of the proteins they encode. See the homepage of the cytochrome P450 Nomenclature Committee for detailed information.
P450s in other species
Animals
Other animals often have more P450 genes than humans do. Reported numbers range from 35 genes in the sponge Amphimedon queenslandica to 235 genes in the cephalochordate Branchiostoma floridae. Mice have genes for 101 P450s, and sea urchins have even more (perhaps as many as 120 genes).
Most CYP enzymes are presumed to have monooxygenase activity, as is the case for most mammalian CYPs that have been investigated (except for, e.g., CYP19 and CYP5). Gene and genome sequencing is far outpacing biochemical characterization of enzymatic function, though many genes with close homology to CYPs with known function have been found, giving clues to their functionality.
The classes of P450s most often investigated in non-human animals are those either involved in development (e.g., retinoic acid or hormone metabolism) or involved in the metabolism of toxic compounds (such as heterocyclic amines or polyaromatic hydrocarbons). Often there are differences in gene regulation or enzyme function of P450s in related animals that explain observed differences in susceptibility to toxic compounds (ex. canines' inability to metabolize xanthines such as caffeine). Some drugs undergo metabolism in both species via different enzymes, resulting in different metabolites, while other drugs are metabolized in one species but excreted unchanged in another species. For this reason, one species's reaction to a substance is not a reliable indication of the substance's effects in humans. A species of Sonoran Desert Drosophila that uses an upregulated expression of the CYP28A1 gene for detoxification of cacti rot is Drosophila mettleri. Flies of this species have adapted an upregulation of this gene due to exposure of high levels of alkaloids in host plants.
P450s have been extensively examined in mice, rats, dogs, zebrafish, and turkeys. CYP1A5 and CYP3A37 in turkeys were found to be very similar to the human CYP1A2 and CYP3A4 respectively, in terms of their kinetic properties as well as in the metabolism of aflatoxin B1.
CYPs have also been extensively studied in insects, often to understand pesticide resistance. For example, CYP6G1 is linked to insecticide resistance in DDT-resistant Drosophila melanogaster and CYP6M2 in the mosquito malaria vector Anopheles gambiae is capable of directly metabolizing pyrethroids. Other cytochromes, such as those in Anopheles gambiae, are under preliminary research for their potential role in pesticide resistance, infectious diseases, and malaria.
Microbial
Microbial cytochromes P450 are often soluble enzymes and are involved in diverse metabolic processes. In bacteria the distribution of P450s is very variable with many bacteria having no identified P450s (e.g. E.coli). Some bacteria, predominantly actinomycetes, have numerous P450s (e.g.,). Those so far identified are generally involved in either biotransformation of xenobiotic compounds (e.g. CYP105A1 from Streptomyces griseolus metabolizes sulfonylurea herbicides to less toxic derivatives,) or are part of specialised metabolite biosynthetic pathways (e.g. CYP170B1 catalyses production of the sesquiterpenoid albaflavenone in Streptomyces albus). Although no P450 has yet been shown to be essential in a microbe, the CYP105 family is highly conserved with a representative in every streptomycete genome sequenced so far. Due to the solubility of bacterial P450 enzymes, they are generally regarded as easier to work with than the predominantly membrane bound eukaryotic P450s. This, combined with the remarkable chemistry they catalyse, has led to many studies using the heterologously expressed proteins in vitro. Few studies have investigated what P450s do in vivo, what the natural substrate(s) are and how P450s contribute to survival of the bacteria in the natural environment.Three examples that have contributed significantly to structural and mechanistic studies are listed here, but many different families exist.
Cytochrome P450 cam (CYP101A1) originally from Pseudomonas putida has been used as a model for many cytochromes P450 and was the first cytochrome P450 three-dimensional protein structure solved by X-ray crystallography. This enzyme is part of a camphor-hydroxylating catalytic cycle consisting of two electron transfer steps from putidaredoxin, a 2Fe-2S cluster-containing protein cofactor.
Cytochrome P450 eryF (CYP107A1) originally from the actinomycete bacterium Saccharopolyspora erythraea is responsible for the biosynthesis of the antibiotic erythromycin by C6-hydroxylation of the macrolide 6-deoxyerythronolide B.
Cytochrome P450 BM3 (CYP102A1) from the soil bacterium Bacillus megaterium catalyzes the NADPH-dependent hydroxylation of several long-chain fatty acids at the ω–1 through ω–3 positions. Unlike almost every other known CYP (except CYP505A1, cytochrome P450 foxy), it constitutes a natural fusion protein between the CYP domain and an electron donating cofactor. Thus, BM3 is potentially very useful in biotechnological applications.
Cytochrome P450 119 (CYP119A1) isolated from the thermophillic archea Sulfolobus solfataricus has been used in a variety of mechanistic studies. Because thermophillic enzymes evolved to function at high temperatures, they tend to function more slowly at room temperature (if at all) and are therefore excellent mechanistic models.
Fungi
The commonly used azole class of antifungal drugs works by inhibition of the fungal cytochrome P450 14α-demethylase.
Plants
Cytochromes P450 are involved in a variety of processes of plant growth, development, and defense. It is estimated that P450 genes make up approximately 1% of the plant genome. These enzymes lead to various fatty acid conjugates, plant hormones, secondary metabolites, lignins, and a variety of defensive compounds.
Cytochromes P450 play roles in plant defense– involvement in phytoalexin biosynthesis, hormone metabolism, and biosynthesis of diverse secondary metabolites. The expression of cytochrome p450 genes is regulated in response to environmental stresses indicative of a critical role in plant defense mechanisms.
The biosynthesis of phytoalexins, antimicrobial compounds produced by some plants, involves the P450 enzymes CYP79B2, CYP79B3, CYP71A12, CYP71A13, and CYP71B15. The first step of camalexin biosynthesis produces indole-3-acetaldoxime (IAOx) from tryptophan and is catalyzed by either CYP79B2 or CYP79B3. IAOx is then immediately converted to indole-3-acetonitrile (IAN) and is controlled by either CYP71A13 or its homolog CYP71A12. The last two steps of the biosynthesis pathway of camalexin are catalyzed by CYP71B15. In these steps, indole-3-carboxylic acid (DHCA) is formed from cysteine-indole-3-acetonitrile (Cys(IAN)) followed by the biosynthesis of camalexin. There are some intermediate steps within the pathway that remain unclear, but it is well understood that cytochrome P450 is pivotal in camalexin biosynthesis and that this phytoalexin plays a major role in plant defense mechanisms.
Cytochromes P450 are largely responsible for the synthesis of the jasmonic acid (JA), a common hormonal defenses against abiotic and biotic stresses for plant cells. For example, a P450, CYP74A is involved in the dehydration reaction to produce an insatiable allene oxide from hydroperoxide. JA chemical reactions are critical in the presence of biotic stresses that can be caused by plant wounding, specifically shown in the plant, Arabidopsis. As a prohormone, jasmonic acid must be converted to the JA-isoleucine (JA-Ile) conjugate by JAR1 catalysation in order to be considered activated. Then, JA-Ile synthesis leads to the assembly of the co-receptor complex compo`sed of COI1 and several JAZ proteins. Under low JA-Ile conditions, the JAZ protein components act as transcriptional repressors to suppress downstream JA genes. However, under adequate JA-Ile conditions, the JAZ proteins are ubiquitinated and undergo degradation through the 26S proteasome, resulting in functional downstream effects. Furthermore, several CYP94s (CYP94C1 and CYP94B3) are related to JA-Ile turnover and show that JA-Ile oxidation status impacts plant signaling in a catabolic manner. Cytochrome P450 hormonal regulation in response to extracellular and intracellular stresses is critical for proper plant defense response. This has been proven through thorough analysis of various CYP P450s in jasmonic acid and phytoalexin pathways.
Cytochrome P450 aromatic O-demethylase, which is made of two distinct promiscuous parts: a cytochrome P450 protein (GcoA) and three domain reductase, is significant for its ability to convert Lignin, the aromatic biopolymer common in plant cell walls, into renewable carbon chains in a catabolic set of reactions. In short, it is a facilitator of a critical step in Lignin conversion.
InterPro subfamilies
InterPro subfamilies:
Cytochrome P450, B-class
Cytochrome P450, mitochondrial
Cytochrome P450, E-class, group I
Cytochrome P450, E-class, group II
Cytochrome P450, E-class, group IV
Aromatase
Clozapine, imipramine, paracetamol, phenacetin Heterocyclic aryl amines
Inducible and CYP1A2 5-10% deficient
oxidize uroporphyrinogen to uroporphyrin (CYP1A2) in heme metabolism, but they may have additional undiscovered endogenous substrates.
are inducible by some polycyclic hydrocarbons, some of which are found in cigarette smoke and charred food.
These enzymes are of interest, because in assays, they can activate compounds to carcinogens.
High levels of CYP1A2 have been linked to an increased risk of colon cancer. Since the 1A2 enzyme can be induced by cigarette smoking, this links smoking with colon cancer.
See also
Steroidogenic enzyme
CYP11 family
References
External links
EC 1.14
Pharmacokinetics
Metabolism
Integral membrane proteins | Cytochrome P450 (individual enzymes) | [
"Chemistry",
"Biology"
] | 5,008 | [
"Pharmacology",
"Pharmacokinetics",
"Cellular processes",
"Biochemistry",
"Metabolism"
] |
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