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54,892,406 | https://en.wikipedia.org/wiki/NGC%20469 | NGC 469 is a spiral galaxy in the constellation Pisces. Located approximately 167 million light-years from Earth, it was discovered by Albert Marth in 1864.
See also
List of galaxies
List of spiral galaxies
References
External links
Deep Sky Catalog
SEDS
469
Pisces (constellation)
Spiral galaxies
004753 | NGC 469 | [
"Astronomy"
] | 66 | [
"Pisces (constellation)",
"Constellations"
] |
54,893,246 | https://en.wikipedia.org/wiki/Internet-in-a-Box | Internet-in-a-Box (IIAB) is a low cost digital library, consisting of a wireless access point with storage, which users nearby can connect to. The hardware and software from which it is built has changed since 2012, as miniaturization of storage space and electronics progressed. As of 2017, its hardware often consists of a Raspberry Pi with a replaceable storage card.
In 2016, Columbia University's Masters in Public Administration in Development Practice (MPA-DP) explored using these boxes in the Dominican Republic for three months.
Distribution of devices assembled by Wiki Project Med Foundation via the Wikipedia Store began in 2024. It ships a Raspberry Pi Zero 2 W with a 256 GB SD card, which contains all of English and Spanish Wikipedia, among other resources.
Digital library
The digital library is composed of multiple modules; modules may be pre-installed, or users may choose which to install. Examples of modules include Wikipedia in a specific language, Wikipedia's Medical Encyclopedia, Khan Academy Lite, and OpenStreetMap. Other content includes Moodle, Nextcloud, MediaWiki, PhET (interactive mathematics and science simulations), TED Talks.
History
The concept grew out of One Laptop per Child's school server project.
See also
Meta: Internet-in-a-Box
Kiwix
Afripedia Project
References
External links
Internet-in-a-Box.org
Project updates
Software repository
Community tech docs
Frequently Asked Questions
Related: PirateBox alternatives, NetHood
Educational technology non-profits
Information and communication technologies for development
Digital library projects | Internet-in-a-Box | [
"Technology"
] | 325 | [
"Information and communications technology",
"Information and communication technologies for development"
] |
67,665,516 | https://en.wikipedia.org/wiki/Window%20well | A window well is a recess in the ground around a building to allow for installment of bigger windows in a basement either below ground or partially below ground. By making it possible to put in a larger window, the window can act as a safer emergency exit in case of fire as well as letting in additional daylight for the enjoyment of the people inside. Such a (basement) window where people can escape through in case of an emergency is sometimes called an egress window.
Minimum window sizes may be required by building code (particularly for bed and living rooms) due to fire safety, which often makes it necessary to install window wells. Window wells are sometimes covered by a window well cover to avoid snow and debris to enter the pit, as well as preventing fall injuries into the window well.
Care should be taken to install window wells correctly to ensure proper drainage and avoid leaks.
See also
Alcove (architecture)
Niche (architecture)
References
Well
Architectural elements | Window well | [
"Technology",
"Engineering"
] | 192 | [
"Building engineering",
"Architectural elements",
"Architecture stubs",
"Components",
"Architecture"
] |
67,665,773 | https://en.wikipedia.org/wiki/CA77.1 | CA77.1 (CA) is a synthetic compound that activates chaperone-mediated autophagy (CMA) by increasing the expression of the lysosomal receptor for this pathway, LAMP2A, in lysosomes. CA77.1 is a derivative of earlier compound AR7(HY-101106), which shows potent CMA activation in vitro but is not suitable for in vivo use. CA77.1 is able to activate CMA in vivo, and demonstrates brain penetrance and favorable pharmacokinetics. It has been shown in animal studies that in vivo administration of CA77.1 to enhance chaperone-mediated autophagy, may help to degrade toxic pathogenic protein products such as tau proteins and has potential applications in the treatment of Alzheimer's disease particularly in improving both behavior and neuropathology in PS19 mice models.
References
Chloroarenes
Quinoxalines
Acetamides
Anilides | CA77.1 | [
"Chemistry"
] | 207 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
67,665,947 | https://en.wikipedia.org/wiki/Crystal%20plasticity | Crystal plasticity is a mesoscale computational technique that takes into account crystallographic anisotropy in modelling the mechanical behaviour of polycrystalline materials. The technique has typically been used to study deformation through the process of slip, however, there are some flavors of crystal plasticity that can incorporate other deformation mechanisms like twinning and phase transformations. Crystal plasticity is used to obtain the relationship between stress and strain that also captures the underlying physics at the crystal level. Hence, it can be used to predict not just the stress-strain response of a material, but also the texture evolution, micromechanical field distributions, and regions of strain localisation. The two widely used formulations of crystal plasticity are the one based on the finite element method known as Crystal Plasticity Finite Element Method (CPFEM), which is developed based on the finite strain formulation for the mechanics, and a spectral formulation which is more computationally efficient due to the fast Fourier transform, but is based on the small strain formulation for the mechanics.
Basic concepts
Crystal plasticity assumes that any deformation that is applied to a material is accommodated by the process of slip, where dislocation motion occurs on a slip system. Further, Schmid's law is assumed to be a valid, where a given slip system is said to be active when the resolved shear stress along the slip system exceeds the critical resolved shear stress of the slip system. Since the applied deformation occurs in the macroscopic sample reference frame and slip occurs in the single crystal reference frame, in order to consistently apply the constitutive relations, an orientation map (e.g. using Bunge Euler angles) is required for each grain in the polycrystal. This orientation information can be used to transform the relevant tensors between the crystal frame of reference and the sample frame of reference. The slip systems are described by the Schmid tensor, which is tensor product of the Burgers vector and the slip plane normal, and the Schmid tensor is used to obtain the resolved shear stress in each slip system. Each slip system can undergo different amounts of shearing, and obtaining these shear rates lies at the crux of crystal plasticity. Further, by keeping track of the accumulated strain, the critical resolved shear stress is updated according to various hardening models (e.g. Voce hardening law), and this recovers the observed macroscopic stress-strain response for the material. The texture evolution is captured by updating the crystallographic orientation of the grains based on how much each grain deforms.
Further reading
References
Continuum mechanics
Deformation (mechanics) | Crystal plasticity | [
"Physics",
"Materials_science",
"Engineering"
] | 536 | [
"Continuum mechanics",
"Deformation (mechanics)",
"Classical mechanics stubs",
"Materials science",
"Classical mechanics"
] |
67,666,317 | https://en.wikipedia.org/wiki/Poseidon%20%28species%29 | Several species share the specific name poseidon, the species descriptor in a binomial name.
These include:
Flax poseidon (F. poseidon), a moth
Hypaeus poseidon (H. poseidon), a spider
Lepidochrysops poseidon (L. poseidon), a butterfly
Polyommatus poseidon (P. poseidon), a butterfly
Thyropygus poseidon (T. poseidon), a millipede
See also
Poseidon (disambiguation)
Latin biological phrases | Poseidon (species) | [
"Biology"
] | 116 | [
"Latin biological phrases"
] |
67,670,204 | https://en.wikipedia.org/wiki/Petko%20Dimitrov | Petko Stoyanov Dimitrov () (16 September 1944 – 29 April 2023) was a Bulgarian marine geologist and oceanographer from the Institute of Oceanology - Bulgarian Academy of Sciences in Varna. He has been an early proponent of the Black Sea deluge hypothesis which gained public notoriety at the end of the XXc.
Biography
Born on September 16, 1944, in the village of Novachene, Sofia Province. In 1969 he graduated from Sofia University "St. Kliment Ohridski”, Faculty of Geology and Geography, specialty geology-geochemistry. From 1969 to 1975 he worked in the uranium mine "Eleshnitsa" as a deputy director. In 1975 he won a competition for a research associate and was employed at the Institute of Oceanology - BAS. In 1979 he defended his dissertation on "Genesis of marine sediments in the peripheral region of the western part of the Black Sea shelf in the Quaternary" under the guidance of Academician Yastrebov and Prof. Aksenov at the Shirshov Institute of Oceanology, Moscow.
He introduced new scientific disciplines for the Bulgaria - "Marine Geology" and "Geoarchaeology".
Scientific Secretary of IO-BAS, Varna, 1977 - 1984; Deputy Director of IO-BAS, Varna, 1984 - 1993; Head of the Department "Marine Geology and Archaeology" of IO-BAS, Varna, 1997 - 2009.
There is original research related to the "Black Sea deluge hypothesis"
Leader and participant in over 30 international scientific expeditions in the Black Sea (with Dr. Robert Ballard 2001, 2002; Woods Hole Oceanographic Institution 2006; Prof. William Ryan 2009, 2011 – project 02–337 "Ancient coastlines of the Black Sea and conditions for human presence", funded by the Bulgarian National Science Fund at the Ministry of Education and Science of Bulgaria ). His is the most sensational, but also the most controversial find in Bulgarian archeology, the so-called "Noah's Plate". It was discovered on July 15, 1985 at a depth of about 93 m and 65 km inland from Varna. There is still no one to acknowledge its authenticity.
He participated in international scientific expeditions to the Pacific Ocean (1982), the Atlantic Ocean and the Mediterranean Sea (1984).
The first Bulgarian scientist studied Manganese nodule in Pacific Ocean.
Membership in scientific organizations: Member of Union of Scientists - Varna, Bulgarian Geological Society, Bulgarian Geographical Society, Foreign member of the National Academy of Sciences of Ukraine.
Honorary citizen of the city of Varna, 2013
Research interests: Black Sea, Geology, Geochemistry, Marine geology, Black Sea deluge hypothesis, alternative sources and energy resources from the bottom of the Black Sea, Maritime history, archeology and geoarcheology, uranium minerals and uranium mining.
Teaching activity: Lecturer in Marine Geology, Lithology and Geochemistry in Nikola Vaptsarov Naval Academy and Varna Free University. Lecturer at the University of Bologna and the University Consortium in Underwater Archeology - Sicily, Italy.
Scientific publications: Author and co-author of over 150 scientific articles and books. Citations: over 1300.
He is the creator of the idea for the application of sapropel sediments from the bottom of the Black Sea as a natural ecological fertilizer and biological products. Patent BG No. 63868, Register No. 104106.
Scientific awards: Medal for scientific contributions "St. St. Cyril and Methodius”- II degree, for realization of the project "Correlation of Geological, Climatic and Historical Events in the Black Sea, Marmara Sea and Mediterranean Sea during the last 25000 years (Noah's Flood Project)".
Participation in films about the Black Sea Flood (Black Sea deluge hypothesis) – „BBC–Horizon–1996 – Noah's Flood“, ZDF „Terra X 56 Die Sintflut“, UFOTV „Dark Secrets of Black Sea“, „Ancient X-Files: Season 2 Episode 8 - Great Flood and Scottish Stone Mystery - National Geographic“ etc.
Collaborator of the Institute of Ancient Civilizations in Sofia.
He was a member of the High Attestation Commission (Scientific Commission for Geological and Geographical Sciences) - 2 mandate.
OUR MEMORY ON LIFE AND SCIENTIFIC ACTIVITY BY PROFESSOR DIMITROV PETKO STOYANOV.
Monographs and books
Димитров П. 1988. Далеч от брегове и фарватери. Варна. Изд. „Галактика“. Библиотека „Нептун“, 161 с., doi:10.13140/RG.2.2.19449.36965/1
Димитров П., Д. Димитров. 2003. Черно море, Потопът и древните митове. „Славена“, Варна, ISBN 954-579-278-7, 91 с., doi:10.13140/RG.2.2.27133.05609
((en)) Dimitrov P., D. Dimitrov. 2004. The Black Sea The Flood and the ancient myths. „Slavena“, Varna, ISBN 954-579-335-X, 91 p., doi:10.13140/RG.2.2.18954.16327
((ru)) Димитров П., Д. Димитров. 2008. Черное море, Потоп и древние мифы. „Славена“, Варна, ISBN 954-579-278-7, 89 с., doi:10.13140/RG.2.2.23148.46729
References
External links
Institute of Oceanology - Bulgarian Academy of Sciences, Varna: Petko Dimitrov
www.researchgate.net
People from Varna, Bulgaria
Sofia University alumni
Bulgarian explorers
Geochemists
Bulgarian geologists
1944 births
Living people | Petko Dimitrov | [
"Chemistry"
] | 1,318 | [
"Geochemists"
] |
67,670,570 | https://en.wikipedia.org/wiki/NGC%203254 | NGC 3254 is a spiral galaxy in the constellation Leo Minor. It was discovered on March 13, 1785, by the astronomer William Herschel. It is a member of the NGC 3254 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
Two supernovae have been observed in NGC 3254:
SN 1941B (type unknown, mag. 15.1) was discovered by Josef J. Johnson on 25 March 1941. [Note: some sources incorrectly list the discovery date as 28 March 1941.]
SN 2019np (type Ia, mag. 13.0) was discovered by Kōichi Itagaki on 9 January 2019. This supernova was the brightest observed in the year 2019.
Gallery
See also
List of NGC objects (3001–4000)
References
External links
Leo Minor
3254
Unbarred spiral galaxies
030895
05685
+05-25-018
F10265+2944
17850313
Discoveries by William Herschel | NGC 3254 | [
"Astronomy"
] | 225 | [
"Leo Minor",
"Constellations"
] |
67,670,735 | https://en.wikipedia.org/wiki/RCA%20Communication%20Systems | RCA Communication Systems is a private label brand used by Discount Two Way Radio Corporation (DTWR) to market its own brand Two-way radio and related communications equipment using the RCA logo under licence from Technicolor SA
History
In 2009, an agreement was made between Discount Two Way Radio Corporation (DTWR) and Technicolor SA to manufacture Two-way radio products under the RCA brand.
RCA Two-way radios is the official sponsor of the United States Bobsled and Skeleton Team for the 2022 Winter Olympic Games in Beijing.
Markets
There are more than 100 authorized resellers of RCA Two-way radios in the US. In Canada, RCA Two-way radios are exclusively distributed by Allcan Distributors.
Products
The RCA Two-way radio range consists of both analog and digital models. The RCA PRODIGI™ is the digital line of Two-way radios. The model RDR26X0 is assembled in the United States.
Two-way radio Models
References
Technology companies
Radio manufacturers | RCA Communication Systems | [
"Engineering"
] | 203 | [
"Radio electronics",
"Radio manufacturers"
] |
67,672,083 | https://en.wikipedia.org/wiki/Benzyl%20gentiobioside | Benzyl gentiobioside is a decyanogenated form of amygdalin. Benzyl gentiobioside occurs in Prunus persica seeds.
References
Benzyl compounds
Glucosides
Disaccharides | Benzyl gentiobioside | [
"Chemistry"
] | 52 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
67,672,745 | https://en.wikipedia.org/wiki/Anaritide | Anaritide (also known as human atrial natriuretic peptide [102-126]) is a synthetic analogue of atrial natriuretic peptide (ANP).
Structure
Anartidine has the following primary structure:
RSSCFGGRMDRIGAQSGLGCNSFRY
or
H-Arg-Ser-Ser-Cys-Phe-Gly-Gly-Arg-Met-Asp-Arg-Ile-Gly-Ala-Gln-Ser-Gly-Leu-Gly-Cys-Asn-Ser-Phe-Arg-Tyr-OH
This structure is identical to residues 102-126 of human preproANP. In comparison, active human ANP comprises resides 99-126 of human preproANP.
Medical uses
Anaritide has been investigated as a potential therapy for acute tubular necrosis but was shown not to improve the dialysis-free survival of these patients. It also appears to exacerbate proteinuria and natriuresis in patients with nephrotic syndrome.
References
Peptides | Anaritide | [
"Chemistry"
] | 231 | [
"Biomolecules by chemical classification",
"Peptides",
"Molecular biology"
] |
67,674,312 | https://en.wikipedia.org/wiki/Elena%20Litchman | Elena Litchman is a professor of aquatic ecology at Michigan State University known for her research on the consequences of global environmental change on phytoplankton.
Education and career
Litchman received an Honors Diploma in biology from Moscow State University, Russia, and a Ph.D. in ecology from the University of Minnesota in 1997. Following graduate work, Litchman held postdoctoral positions at the Smithsonian Environmental Research Center, the Swiss Federal Institute for Aquatic Science and Technology, and Rutgers University. From 2003 to 2005, Litchman was a research scientist at Georgia Institute of Technology. In 2005, Litchman took a position in the Zoology Department of Michigan State University and the W.K. Kellogg Biological Station. She has been named a MSU Foundation Professor at Michigan State University where she works in the Department of Integrative Biology.
Research
Litchman's Ph.D. research examined the impact of changing light levels on competition in phytoplankton. She introduced the use of trait-based ecology for phytoplankton in papers published in 2007 and 2008. Prior to these publications, trait-based ecology had been implemented in terrestrial science and Litchman was the first to apply these ideas to marine research. Key traits in phytoplankton include light, nutrient use, morphology, predation, and temperature, and Litchman has combined these traits to mathematically define phytoplankton community structure. Litchman's research has examined the connection between the size of phytoplankton over evolutionary time and nutrient limitation which, in turn, impacts marine food webs under changing climates. Through eco-evolutionary modeling, Litchman's research has shown that in the future warmer oceans will cause phytoplankton to shift towards polar regions.
Selected publications
Awards
Presidential Early Career Award for Scientists and Engineers (PECASE) Award (2010) "For integration of theoretical and experimental studies to predict how global environmental change modifies physical processes and phytoplankton diversity and evolution within lakes, and for interdisciplinary training and outreach to K-12 teachers."
Petersen Foundation Excellence Professorship Award, Germany (2017)
G. Evelyn Hutchinson Award from the Association for the Sciences of Limnology and Oceanography (2021)
References
External links
University of Minnesota alumni
Moscow State University alumni
Michigan State University faculty
Ecologists
Women ecologists
Evolutionary biologists
Living people
Year of birth missing (living people)
Recipients of the Presidential Early Career Award for Scientists and Engineers | Elena Litchman | [
"Environmental_science"
] | 498 | [
"Ecologists",
"Environmental scientists"
] |
70,562,226 | https://en.wikipedia.org/wiki/Shabnam%20Akhtari | Shabnam Akhtari is a Canadian-Iranian mathematician specializing in number theory, and in particular in Diophantine equations, Thue equations, and the geometry of numbers. She is a professor of mathematics at Pennsylvania State University.
Education and career
Akhtari graduated from the Sharif University of Technology, in Tehran, in 2002 with a bachelor's degree in mathematics. She went to the University of British Columbia for graduate study in mathematics, completing her Ph.D. there in 2008. Her dissertation, Thue Equations and Related Topics, was supervised by Mike Bennett.
She was a postdoctoral researcher at Queen's University at Kingston in Canada, the Max Planck Institute for Mathematics in Germany and the Centre de Recherches Mathématiques in Canada before joining the University of Oregon faculty as an assistant professor of mathematics in 2012. She was tenured as an associate professor there in 2018.
Recognition
Akhtari is the 2021–2022 winner of the Ruth I. Michler Memorial Prize of the Association for Women in Mathematics.
References
External links
Home page
Year of birth missing (living people)
Living people
21st-century Iranian mathematicians
Iranian women mathematicians
Sharif University of Technology alumni
University of British Columbia alumni
University of Oregon faculty
Number theorists
21st-century Iranian women scientists | Shabnam Akhtari | [
"Mathematics"
] | 255 | [
"Number theorists",
"Number theory"
] |
70,562,678 | https://en.wikipedia.org/wiki/Feminist%20science%20and%20technology%20studies | Feminist science and technology studies (feminist STS) is a theoretical subfield of science and technology studies (STS), which explores how gender interacts with science and technology. The field emerged in the early 1980s alongside other relativist theories of STS which rejected the dominance of technological determinism, proposing that reality is multiple rather than fixed and prioritizing situated knowledges over scientific objectivity. Feminist STS's material-semiotic theory evolved to display a complex understanding of gender and technology relationships by the 2000s, notable scholars producing feminist critiques of scientific knowledge and the design and use of technologies. The co-constructive relationship between gender and technology contributed to feminist STS's rejection of binary gender roles by the twenty-first century, the field's framework expanding to incorporate principles of feminist technoscience and queer theory amidst widespread adoption of the internet.
Historical areas of research include policy development, reproduction, pharmaceuticals, design and use of consumer products, and engineering cultures, researchers exploring ways gender creates and is created by individuals or groups interacting with non-human actors. Feminist STS scholars prioritize this relationship of co-construction to emphasize that neither gender nor technology and science exists before their interaction, but instead, reality exists in the social and material interactions, producing these concepts as a result. Establishing this material-semiotic framework involved a decades-long process of internal negotiation between feminist STS researchers, binary gender presentations of past STS research undergoing detailed critique to reframe these understandings to reflect the field's stance on gender not as fixed, but as multiple and flexible.
Key concepts of feminist STS include material-semiotics, situated knowledges, and social constructivism. The discipline has contributed material-semiotic theory to contemporary STS research but has received criticism for the inability to universalize concepts in its research, limiting the field's impact.
Background and context
Early 1980s – late 1990s
Feminist STS emerged as a social theory in the early 1980s prompted by an introduction of feminist theory into science and technology studies, partially credited to Donna Haraway's 1985 article "A Cyborg Manifesto". The discipline gained prominence in STS alongside Social construction of technology (SCOT) and Actor-network theory (ANT) as a response to criticisms of objectivity and technological determinism. Early feminist STS literature focused on gender differences in technology use, such as Claude S. Fischer's study of the residential telephone and Cynthia Cockburn and Susan Ormrod's study of the microwave oven.
Including Adele Clarke and Theresa Montini's arena analysis of abortifacient technology RU486, early feminist STS researchers used the case study method to show that men and women interact with technology in different ways. These studies were significant for establishing how people come to associate technology with masculinity or femininity through social interaction. In addition to determining masculinity and femininity are multiple rather than binary constructs, research showed evidence of situated knowledges, or, the idea that there is no such thing as a neutral subject or researcher. From establishing a presence in pharmaceutical and commercial technologies, feminist STS expanded into questioning the dominant authority of science by the early 1990s, borrowing methodology from ANT to expand upon prior research. Theory and methods from SCOT were also incorporated into the discipline as researchers began to explore the process through which gender becomes embedded within technology, with studies adopting principles of social constructivism, for example, Judy Wajcman's research on the culture of engineering. Other feminist STS studies throughout the 1990s were also influenced by the work of Steve Woolgar and his research on how technology is designed with users in mind, such as Trevor Pinch and Nancy Oudshoorn, who continued research into user configuration into the 2000s.
Interrogating scientific knowledge through introducing new theories and methods to feminist STS led to conflicts within the field related to the categories of sex and gender and how they are used in research. Trevor Pinch and Wiebe Bijker, SCOT researchers, proposed "interpretive flexibility" to explain different social group's varied responses to technology, gender reflected as a relevant social group. Pinch was critical of Woolgar's previous research on users of technology as the design process of technological products had not been considered, proposing "symmetry", where humans impact technology equal to how technology impacts humans. The symmetry approach addressed the co-constructive relationship between gender and technology, though was critiqued for ignoring historically-relevant power imbalances in how gender and technology relate to one another.
Wendy Faulkner became a notable critic of symmetry, encouraging an approach balancing symmetry's optimism with feminism's characteristic pessimism, which recognizes science and technology's relationship to hegemonic masculinity. This critique endorsed a return of the discipline to Donna Haraway's metaphor of the cyborg to assert women's presence in both technology design and technological cultures historically stereotyped as masculine, affirming the necessity of feminine characteristics in both design and use of technology. Faulkner addressed power imbalances not addressed by the social-constructivist approach, but the reliance on gendered labels was criticized for heteronormativity within a field which had recognized multiple gender representations distinct from binary sex roles. Faulkner's research presented a feminist perspective in which men inherently possessed masculinity, and women femininity, neglecting the material-semiotic nature of gender and technology adopted by feminist STS scholars proposing gender as co-created alongside, not prior-to, technology.
Judy Wajcman commented on the conflict and negotiation occurring within the discipline's research from the early 1980s until the turn of the century, crediting these debates for the complex understanding of gender-technology relationships developed by feminist STS. Cyberspace introduced new possibilities for research into the co-construction of gender and technology, both of which were no longer conceptualized by feminist STS as separate and fixed, but interconnected and multiple.
2000s – present
Building upon prior research from two decades of feminist STS literature, studies adopted principles based on updated frameworks at the turn of the millennium, such as Ellen van Oost's research into how gender becomes configured into electric shavers, Ruth Schwartz Cowan's study on technological innovation increasing women's labor, and Jennifer R. Fishman's exploration of pharmaceutical technology's potential to designate potential consumers as dysfunctional. Research regarding decades of body modification practices in queer communities introduced material connections between gender and technology through individuals who represented and created diverse genders for themselves through physical alteration of their bodies, further establishing academic literature on gender beyond binary terminology and connecting queer theory to feminist STS.
Compared to past studies which were restricted to questioning the objectivity of scientific knowledge through the language used in descriptions of biological sex, researchers approached reproductive studies through a gender-based framework, Rayna Rapp emphasizing feminist ideology in her study of the impact of reproductive biomedicalization on women, while Laura Mamo's exploration of knowledge negotiation in lesbian reproduction six years later emphasized situated knowledges. Both studies found multiple possibilities of femininity reflected in their research subjects, similar to Wendy Faulkner's conclusions in her 2001 study on limitations to women's participation in engineering which proposes a radical shift in culture to emphasize the necessity of women in technology development to counteract masculinity being embedded in technological artefacts by men who create them. As with past feminist STS research, these studies were similarly critiqued for use of binary concepts like masculinity and femininity which suggested gender existed separate from its relationship to technology, contradicting the material-semiotic stance of the field.
Continuing with the user trials conducted alongside Trevor Pinch, Nelly Oudshoorn problematized creating technologies designed for use by everyone as different users have different needs. Oudshoorn's research explored the development of two digital cities, New Topia and DDS, created by development teams with intentions of being inclusive to a diverse range of users. By not considering needs of users which were impacted by identity, specifically gender, assumptions were made in the design process based on the designers gender, embedding these gendered assumptions into the technology. As the software engineers were male, the conclusion presented was that their products reflected masculinity, and though this acknowledges the co-construction of gender and technology, this conclusion was critiqued for reliance on binary historical concepts where gender is possessed rather than created.
Gender as an interactive, social performance in feminist STS is an achievement resulting from the historical evolution of feminism from the postmodern age in the 1970s to the feminist technoscience of the digital age, the nuances of this fluid history of many feminisms presented by Judy Wajcman in 2010. This complex process is a significant discovery, as much of the field's research prior to this point implied that all men possessed a fixed masculinity, contrasting researcher's claims of rejecting binary gender descriptions in their research. "Technofeminism" in STS strengthened connections between feminist STS and queer studies due to this overlapping gender theory, shifting the discipline towards research which no longer relied on determinism in labelling their subjects to criticize gender inequality and power dynamics in STS. This shift in epistemology appeared in research through studies on biohacking technologies, such as hormone injection, health supplements, and body implants, establishing a literal connection to Haraway's cyborg metaphor through physically linking bodies and machines in addition to a theoretical connection to the power these links hold to transcend the limits of the human body, specifically gender.
Key concepts
Material-semiotics
Material-semiotic theory is a relativist theory in which the social does not exist separately from the material, used in feminist STS to describe the co-constructive relationship between humans and technology.
Situated knowledges
Situated knowledges are knowledges created from the subject's perspective, as opposed to knowledge written about a subject. Feminist STS relies on knowledge from marginalized realities, termed "subjugated knowledges", to explore realities beyond the understanding of scientific explanation.
Social constructivism
Social constructivism is a theoretical perspective in which knowledge is created through social interactions between entities, human or non-human.
Impact
Contributions
Feminist STS has strengthened the stance of anti-objectivity within science and technology studies through its emphasis on situated knowledges. By positioning science as one of many perspectives on reality, feminist STS critiqued neutrality in science, asserting that knowledge is always created from a particular perspective regardless of whether that perspective is acknowledged or not. This rejection of a possibility to view the world as though one is separate from the world reinforced material-semiotics in the greater discipline.
Criticisms
The post-structuralism proposed by feminist STS's theory of multiple realities has been criticized by reductionist scholars who propose the existence of a single reality separate from human interaction. The discipline's reliance on feminist criticism has potentially contributed to alienating potential supporters, pushing them closer to theories of technological determinism.
References
Feminism and education
Science and technology studies | Feminist science and technology studies | [
"Technology"
] | 2,218 | [
"Science and technology studies"
] |
70,563,587 | https://en.wikipedia.org/wiki/ATT%26CK | The Adversarial Tactics, Techniques, and Common Knowledge or MITRE ATT&CK is a guideline for classifying and describing cyberattacks and intrusions. It was created by the Mitre Corporation and released in 2013.
Rather than looking at the results of an attack (aka an indicator of compromise (IoC)), it identifies tactics that indicate an attack is in progress. Tactics are the “why” of an attack technique.
The framework consists of 14 tactics categories consisting of "technical objectives" of an adversary. Examples include privilege escalation and command and control. These categories are then broken down further into specific techniques and sub-techniques.
The framework is an alternative to the cyber kill chain developed by Lockheed Martin.
ATT&CK Matrix for Enterprise
The ATT&CK Matrix for Enterprise is a comprehensive framework that is presented as a kanban board-style diagram. It defines 14 categories of tactics, techniques and procedures (TTPs) used by cybercriminals with the associated techniques and sub-techniques.
Reconnaissance
Reconnaissance is the initial stage of information gathering for an eventual cyberattack.
There are 10 techniques – including the use of network scanning, social engineering and Open-source intelligence (OSINT).
References
External links
Github repository
Classification systems
Computer standards
Mitre Corporation | ATT&CK | [
"Technology"
] | 266 | [
"Computer security stubs",
"Computer standards",
"Computing stubs"
] |
70,564,555 | https://en.wikipedia.org/wiki/Ultrasound-switchable%20fluorescence%20imaging | Ultrasound-switchable fluorescence (USF) imaging is a deep optics imaging technique. In last few decades, fluorescence microscopy has been highly developed to image biological samples and live tissues. However, due to light scattering, fluorescence microscopy is limited to shallow tissues (about 1 mm). Since fluorescence is characterized by high contrast, high sensitivity, and low cost which is crucial to investigate deep tissue information, developing fluorescence imaging technique with high depth-to-resolution ratio would be promising.. Recently, ultrasound-switchable fluorescence imaging has been developed to achieve high signal-to-noise ratio (SNR) and high spatial resolution imaging without sacrificing image depth.
Basic principle
The theoretical model was first proposed by Yuan in 2009, he developed an ultrasound-modulated fluorescence based on a fluorophore-quencher-labeled microbubble system which can control the fluorescent emission inside the ultrasound-focal zone to increase the spatial resolution and SNR o f the imaging. In terms of the USF imaging principle, a short ultrasound pulse is applied to activate the fluorescent emission inside the ultrasound focal volume without triggering fluorescence outside of the ultrasound focal volume. Thus, the fluorophores distribution in the ultrasound focal zone can be distinguished and imaged by screening the target. Two basic elements are required in USF imaging technique, the first is unique USF contrast agents whose fluorescence emission can be controlled by a focused ultrasound wave. Secondly, a sensitive USF imaging system is also required to detect the signal and suppress the background noise.
Imaging contrast agents
At present, two types of contrast agents have been developed.
Fluorophore-quencher-labeled microbubble
The first type is fluorophore-quencher-labeled microbubble which is first discovered by Yuan in 2019, and developed by Liu et al. in 2014. The basic principle of this type of contrast agent is to change the fluorophore concentration on the microbubble surface. In 2000, Morgan et al. found that negative ultrasould wave can make the microbubble several times bigger. As a result, the distance between quencher and fluorophore on microbubble surface become larger (the concentration of the flurophore on the surface are reduced) which means the quenching efficiency is extremely decreased and the fluorophore shows high emission efficiency (ON state). The microbubble outside the ultrasound focal zone keep the same small size during the whole process, so the quenching efficiency is always high enough to suppress the fluorophore emission (OFF state).
Fluorophore-labeled thermosensitive polymers or fluorophore-encapsulated nanoparticles (NPs)
The second type of contrast agents is fluorophore-labeled thermosensitive polymers or fluorophore-encapsulated nanoparticles (NPs). The critical part of this kind of agent is the combination of the thermo-sensitive carrier and environment-sensitive (usually polarity-sensitive) fluorophore labeled on it. When the environment temperature is under a certain threshold (Tth1), the polarity of the carrier on which the fluorophore shows quite low emission efficiency (OFF state). When focused ultrasound is applied, the focal zone is heated above a temperature threshold (Tth2) and the structure of the thermo-sensitive carrier will be changed which makes the polarity of it changes too, therefore, the polarity-sensitive fluorophore will be swathed on. During the whole process, the fluorophore outside of the ultrasound focal zone keep switched off because the temperature is under Tth1.
USF imgaing system
The purpose of the USF imaging system is to sensitively detect the USF signal and dramatically suppress the background noise.
The image system first dramatically increase the system sensitivity by adopting a lock-in amplifier and a cooled photomultiplier tube(PMT);
Then the system use a correlation algorithm to distinguish the USF signal from the background noise;
Also, it detects only the change of the fluorescence signal caused by the ultrasound, The modulated-frequency excitation laser keep running all the time, the ultrasound-induced temperature rise change the amplitude of the fluorescence signal in modulated frequency. After interfering with a phase-locked reference signal, the lock-in amplifier reports the USF signal;
The system can also reduce laser leakage by using several emission filters.
Signal to Noise ratio
USF imaging can increase the SNR by differentiating signal photons from background photons. The background photons may come from autofluoresence, light scattering, imperfect contrast agents and laser leakage. To reduce autofluoresence, the NIR fluorophore can be adopted since the biological tissue components produce least autofloresence in NIR region. According to rayleigh theory:
I(r,θ) = 1/λ4
The light with large wavelength scatter less, so the light scattering which result in part of the background noise can be reduced. Also, by adopting ultrasound to control the fluorescent emission, the signal fluorophore can be easily differentiate from the background fluorophore. As we mentioned above, the laser leakage can be minimized by emission filters.
Spatial resolution
When using second type of contrast agents (fluorophore-labeled thermosensitive NPs), the spatial resolution can be further improved based on two mechanisms.
Nonlinear acoustic effect
Acoustic diffraction is the main obstacle to increase the spatial resolution. By controlling ultrasound exposure power, the nonlinear acoustic effect can occur, as a result, a part of acoustic energy at the fundamental frequency can be transferred to higher harmonic frequency components in the focal volume which can be more tightly focused. This is the major reason that nonlinear acoustic effect can reduce the ultrasound-induced temperature focal size.
Thermal confinement
The spatial resolution of the USF technique is determined by the size of the region where the fluorophores can be switched ON. Only the temperature is above the threshold, the fluorephore can be switched on. However, due to the thermal diffusion or conduction, ultrasound-induced thermal energy need to be confined within the focal volume size by controlling the ultrasound exposure time, so the fluorophores can be switched ON is usually smaller than the actual focal size of the ultrasound.
Applications
The USF technique can be combined with a light-pulse-delay technique and a photon counting technique to achieve high-resolution imaging in a deep turbid medium. In 2016, Cheng et al. achieved high-resolution fluorescence imaging in centimeter-deep tissue phantoms with high SNR and high sensitivity, they synthesized and characterized a NIR extremely environment-sensitive fluorophore, ADP(CA)2, and a family of USF contrast agents based on this dye. In the recent study in 2019, Yao et al. first achieved in vivo ultrasound-switchable fluorescence imaging in mice with high resolution. ICG-encapsulated PNIPAM nanoparticles was adopted as contrast agents which is quite stable in biological environment. Compared with CT imaging results, they found USF imaging maintained high sensitivity and specificity in deep tissue.
References
Ultrasound
Optical microscopy techniques
Fluorescence | Ultrasound-switchable fluorescence imaging | [
"Chemistry"
] | 1,505 | [
"Luminescence",
"Fluorescence"
] |
70,565,332 | https://en.wikipedia.org/wiki/CoreXY | CoreXY is a technique used to move the printhead of a 3D printer or the toolhead in CNC machines in the horizontal plane. The advantage of this technique is that the two motors used to perform the movement in the horizontal plane are stationary and do not have to move themselves, which can result in less moving mass. Instead, drive belts are used which are connected in an intricate way to provide movement in a Cartesian coordinate system. Compared to conventional Cartesian 3D printers for fused filament, it can provide increased printing speed due to less moving mass.
Movement
For movement along the x-axis, both motors must rotate in the same direction. For movement along the y-axis, the motors must rotate in opposite directions. If only one motor rotates, the movement will be diagonal.
The movement can be mathematically described as follows. If A is the movement of the first motor and B the movement of the second motor, the movement in the x and y directions is given by:
Compared to conventional printers
Other Cartesian 3D printers which do not use the CoreXY technique most commonly also use two motors for the xy-plane, but where one motor is independently responsible for movement along the x-axis, and the other independently responsible for movement along the y-axis. This is sometimes called a Cartesian technique. "Bed slinger" is a cartesian variant where the build surface moves along the y-axis, and the print head moves along the x-axis, and this technique is used on amongst other the Prusa i3 and clones.
See also
Delta robot, a parallel robot mechanism used in delta 3D printers
SCARA, a robot arm-like mechanism used in 3D printers
Voron 2.4, a CoreXY printer with open source hardware and software
References
Mechanisms (engineering)
3D printing | CoreXY | [
"Engineering"
] | 367 | [
"Mechanical engineering",
"Mechanisms (engineering)"
] |
70,567,562 | https://en.wikipedia.org/wiki/SAAM%20II | SAAM II, short for "Simulation Analysis and Modeling" version 2.0, is a renowned computer program designed for scientific research in the field of bioscience. It is a descriptive and exploratory tool in drug development, tracers, metabolic disorders, and pharmacokinetics/pharmacodynamics research.
It is grounded in the principles of multi-compartment model theory, which is a widely-used approach for modeling complex biological systems. SAAM II facilitates the construction and simulation of models, providing researchers with a friendly user interface allowing the quick run and multi-fitting of simple and complex (linear and nonlinear) structures and data. SAAM II is used by many Pharma and Pharmacy Schools as a drug development, research, and educational tool.
Features
The compartmental module
SAAM II offers a user-friendly interface that eliminates the need for coding. Within the compartmental module, users can construct models effortlessly by drag-and-dropping various model components, such as circles, arrows, and boxes. To simulate the model's behavior, creating model conditions is a straightforward process. By employing drag-and-drop experiment-building icons, users can directly specify inputs and sampling sites with ease.
The non-compartmental module (numerical module)
The Numerical module is also available but less frequently used; it lets you write directly the equations of the model or model directly the data by predefined functions. The latter allows you to carry out a non-compartmental analysis of the data.
popKinetics add-on
Funded by NIH, popKinetics is specifically developed for population analysis of compartmental models built within SAAM II. popKinetics offers the computation of two approaches for population parameter estimation: the Standard Two-Stage and Iterative Two-Stage methods. The Two-Stage methods may be favored when simplicity, computational efficiency, and minimal assumptions are desired in analyzing the population.
Validation
The results obtained from SAAM II have received indirect validation through extensive usage over many years, replication of modeling in other programs, and publication in peer-reviewed journals. Validation of the software's numerical performance was carried out against WinNonlin. In general, there was good agreement (<1% difference) between SAAM II and WinNonlin in terms of parameter estimates and model predictions.
Applications and Notable Work
1. Pharmacokinetics and Pharmacodynamics (PK/PD) Research:
Optimization of drug dosing regimens for enhanced therapeutic outcomes.
Modeling drug absorption, distribution, metabolism, and excretion in the body.
Studying drug-drug interactions and predicting their effects.
Indirect and custom PD.
2. Population Pharmacokinetics:
Analyzing drug responses across diverse patient populations with Two-stage methods.
Personalized medicine: Tailoring drug dosing based on individual patient characteristics.
3. Systems Biology:
Modeling complex biological networks and cellular processes.
Understanding signal transduction pathways and regulatory networks.
Investigating disease pathways and molecular interactions.
4. Biotechnology:
Design and optimization of bioprocesses for pharmaceutical and biotechnological industries.
Predicting the behavior of bioreactors and biocatalysts.
5. Metabolic Diseases Research:
Studying metabolic disorders and their underlying mechanisms.
Analyzing glucose-insulin dynamics and its relevance in diabetes research.
6. Tracer Studies:
Quantitative assessment of the kinetics of radiolabeled compounds.
Investigating tracer distribution and clearance in the body.
7. Experimental Design:
Designing optimal experiments to gather data for parameter estimation and model validation.
Assessing the sensitivity of model parameters to different experimental conditions.
8. Biological Modeling in Education:
SAAM II as an educational tool for teaching bioscience and systems modeling.
Demonstrating concepts of pharmacokinetics and systems biology in academic settings.
9. Peer-Reviewed Publications:
SAAM II is used in various research studies and is cited in more than 50 peer-reviewed scientific journals per year (Google Scholar).
Notably, the glucose-insulin Minimal Models that are used in clinical trials to quantify insulin improvements of antidiabetic treatments, are implemented in SAAM II.
SAAM II Development and Distribution
In the early 1950s, Mones Berman and others at the NIH worked on problems in radiation dosimetry. Mones decided that compartmental models (systems of differential equations) were the best way to analyze the transient (kinetic) data being collected. He started the development of a software tool that eventually became known as SAAM. The power of SAAM was its dictionary that made it possible for a user to sketch their model, and then using the dictionary and a set of rules, create an input file directly from the sketch. SAAM took this information and created the system of differential equations that described the model. This meant that the user could think about biology/pharmacology while the program did the mathematics and statistics behind the scenes. It was a very popular program, but one had to visit the NIH and work with Mones to learn how to use the program.
Between 1986 and 1994, the University of Washington working through its Resource Center for Kinetic Analysis in the Center for Bioengineering, led by Prof David Foster with the help of Loren Zech from NIH, rewrote code including a strategic user interface, which led to SAAM II. The first version was released on the SUN in 1993. The PC version was released in 1994. Through several grants, in the 2000-2012 period, Foster and Vicini worked on generating the modern version 2.1, including a population analysis add-on called popKinetics.
In 2012, the Epsilon Group, a Medical Automation Company in Virginia licensed the commercial rights to improve and distribute the software.
In 2022, the commercial rights to develop and distribute SAAM II software up to current version 2.3.3 were licensed to Nanomath LLC, a consulting and software company headquartered in Washington. The leadership and management of SAAM II were assumed by Simone Perazzolo, a scientist with experience in computational modeling of biological and pharmacological systems.
Main computational algorithms
SAAM II utilizes three types of integrators for Ordinary Differential Equation (ODE) solving:
RK 4-5th order: A 4th-5th order Runge-Kutta methods, which is a numerical technique for solving ODEs.
Pade approximation of the matrix exponential: This method is based on approximating the matrix exponential using Pade approximants, providing an efficient approach for solving ODEs.
Rosenbrock methods: SAAM II employs typical Rosenbrock methods, which are a class of implicit Runge-Kutta methods suitable for stiff ODEs (those with widely varying time scales).
SAAM II employs parameter optimization for multiple data fitting, utilizing a modified nonlinear weighted non-linear least-squares method derived from the Gauss-Newton algorithm. In regression tasks, users have the flexibility to create a weighting scheme based on either the error in the data or the model.
Additionally, SAAM II offers a Bayesian Maximum A Posteriori (MAP) option, allowing users to explore Bayesian parameter estimation. This feature enhances the analysis by incorporating prior knowledge and uncertainty into the parameter estimation process.
To assess the reliability of parameter estimates, SAAM II provides posterior and practical identifiability features. These utilize Fisher's information matrix and covariance matrix of the estimates to evaluate the quality of parameter identification, also in case of complex structures and numerous unknown variables.
Furthermore, SAAM II includes local parameter sensitivity, batch analysis, and in silico populations features, both of which are convenient tools for gaining insights into the model's behavior and assessing the impact of parameter changes on model outcomes.
Education
SAAM II can be found in curricula in many American and worldwide institutions, such as engineering, physics, and pharmacy schools.
References
Bioinformatics software
University of Washington projects | SAAM II | [
"Biology"
] | 1,607 | [
"Bioinformatics",
"Bioinformatics software"
] |
70,568,068 | https://en.wikipedia.org/wiki/Hemimycena%20tortuosa | Hemimycena tortuosa, commonly known as the dewdrop bonnet, is a species of basidiomycete fungus of the family Mycenaceae, in the order Agaricales.
Synonyms
Helotium tortuosum (P.D.Orton) Redhead
Mycena tortuosa P.D.Orton 1960
References
Mycenaceae
Fungi described in 1860
Fungus species | Hemimycena tortuosa | [
"Biology"
] | 82 | [
"Fungi",
"Fungus species"
] |
70,568,179 | https://en.wikipedia.org/wiki/Lugdi | Lugdi or Jhol (Hindi: Jhol) is an alcoholic drink produced North Indian state of Himachal Pradesh. It is traditionally prepared from cooked cereal grains, especially rice or barley. It is prepared by boiling barley grains or rice and some local herb known as Phab in water and then fermenting the material. The cereals are left in mesophilic conditions for fermentation and consumed undistilled.It is consumed in many district of Himachal Pradesh, such as kinnaur, lahaul and spiti, chamba ,kullu and kangra
It is usually made during the summer season, as the weather and environment help the fermentation process. The drink is reserved for the winter season as it helps to keep the body warm. It is consumed on festive occasions, religious festivals and other social gatherings.Jhol یا Jhol (هندی: Jhol) یک نوشیدنی الکلی است که در ایالت هیماچال پرادش در شمال هند تولید می شود . به طور سنتی از غلات پخته شده به ویژه برنج یا جو تهیه می شود.It is consumed by many local tribes in Himachal Pradesh, such as Kinnara, Lahaula, Swangia and Pangwala.
In 1965, a report published by the Planning Commission, Government of India, noted that there was a ban on the sale of Lugdi, but it was being sold despite the ban.
In popular culture
The drink was featured in the 2013's Ranbir Kapoor and Deepika Padukone starrer Hindi film Yeh Jawaani Hai Deewani.
See also
Chulli
Feni (liquor)
Sonti (rice drink)
Rice wine
List of Indian drinks
References
Indian alcoholic drinks
Indian distilled drinks
Traditional Indian alcoholic beverages
Adulteration
Alcohol in India | Lugdi | [
"Chemistry"
] | 431 | [
"Adulteration",
"Drug safety"
] |
70,568,553 | https://en.wikipedia.org/wiki/Henry%20Segerman | Henry Segerman (born 1979 in Manchester, UK) is an Associate Professor of mathematics at Oklahoma State University in Stillwater, Oklahoma who does research in three-dimensional geometry and topology, especially three-manifolds, triangulations and hyperbolic geometry.
He was the first person to publish a book on mathematical 3D printing, and is also a recreational mathematician and mathematical artist with expertise in virtual reality. His frequent collaborators include Vi Hart, Elisabetta Matsumoto and Saul Schleimer.
Education and career
Segerman received his Master of Mathematics (MS) at the University of Oxford (2001) and then his PhD at Stanford University (2007) for the dissertation "Incompressible Surfaces in Hyperbolic Punctured Torus Bundles are Strongly Detected" under Steven Paul Kerckhoff.
He was a Lecturer at the University of Texas at Austin (2007–2010) and was a Research Fellow at University of Melbourne (2010–2013). He became an Assistant Professor at Oklahoma State University (2013–2018) and then an Associate Professor there in 2018 until the present.
Segerman's research lends itself to mathematics with a strong visual component. This led directly to his involvement with 3D printing. In 2016 he wrote the book Visualizing Mathematics With 3D Printing. Laura Taalman in a review said, "Segerman's book is an inside tour of mathematics with breathtaking 3D-printed scenery."
3D printing
Mathematicians used to rely on wooden or plaster models to visualizing complex geometrical shapes. Nowadays, if they can be described mathematically, we can "print" them with 3D printers. Segerman uses mathematical tools including quaternions, Euclidean and non-Euclidean geometries and stereographic projection to create instructions for 3D printers. Sometimes the goal is to produce a work of art. Sometimes it is to shed light on four-dimensional geometry or some other field such as mathematical group theory. Sometimes it is both. One of his sculptures depicts a set of monkeys joined together to form a 4-dimensional hypercube.
Segerman's techniques help us visualize a four dimensional world. Just as the frame of a cube can cast a shadow on a flat wall, Segerman makes analogous shadows of four dimensional objects via a 3D printer. Segerman has also explored kinetic artwork, designing mechanisms that move in unusual or seemingly paradoxical ways.
Recreational mathematics
Segerman has appeared as a recreational mathematician at Gathering 4 Gardner conferences and is a frequent contributor to Numberphile.
Combining his interests in mathematics and art he is one of 24 mathematicians and artists who make up the Mathemalchemy Team.
In another foray into recreational mathematics Segerman founded Dice Lab with mathematical artist Robert Fathauer. Using computer search and help from fellow recreational mathematician Robert Bosch, they created a "numerically balanced" 120-sided die in the shape of a disdyakis triacontahedron. It is the "biggest, most complex fair die possible". They concede that the die is "expensive and there’s no real use for it", but it's still theoretically interesting.
Selected papers
Segerman does research in three-dimensional geometry and topology. Papers published in this area include:
2020 "Ray-marching Thurston geometries", arXiv:2010.15801 [math.GT, cs.GR, math.DS], [with Coulon, Matsumoto and Trettel], October 2020
2010 "Veering triangulations admit strict angle structures" [with Hodgson, Rubinstein and Tillmann] Geometry & Topology, November 2010, 15(4)
2015 "1-efficient triangulations and the index of a cusped hyperbolic 3-manifold", [with Garoufalidis, Hodgson and Rubinstein], Geometry & Topology 19 (2015), pp. 2619–2689
A second major interest, with some overlap, is mathematical visualization & art. Papers published in this area include:
2014 "The Quaternion Group as a Symmetry Group", [with Vi Hart], Proceedings of Bridges 2014: Mathematics, pp. 143–150
2012 "3D printing for mathematical visualisation", Math. Intell. 34(4) December 2012, pp. 56–62
Awards
The paper "The Quaternion Group as a Symmetry Group" (with Vi Hart) was republished in The Best Writing on Mathematics 2015.
The video "Non-Euclidean Virtual Reality Using Ray-Marching was a winner in the 2019 We Are Mathematics Video Competition.
References
External links
Henry Segerman website
Living people
1979 births
21st-century English mathematicians
21st-century American mathematicians
3D printing specialists
Recreational mathematicians
Mathematics popularizers
Stanford University alumni
Alumni of the University of Oxford
Oklahoma State University faculty
University of Texas at Austin faculty | Henry Segerman | [
"Mathematics"
] | 986 | [
"Recreational mathematics",
"Recreational mathematicians"
] |
70,569,507 | https://en.wikipedia.org/wiki/Hemimycena%20cephalotricha | Hemimycena cephalotricha is a species of basidiomycete fungus of the family Mycenaceae, of the order Agaricales.
It is native to the southwest of Western Australia.
References
External links
Species Fungorum
Mycenaceae
Fungi described in 1982
Fungi of Australia
Fungus species | Hemimycena cephalotricha | [
"Biology"
] | 65 | [
"Fungi",
"Fungus species"
] |
70,569,824 | https://en.wikipedia.org/wiki/Structured%20illumination%20light%20sheet%20microscopy | Structured illumination light sheet microscopy (SI-LSM) is an optical imaging technique used for achieving volumetric imaging with high temporal and spatial resolution in all three dimensions. It combines the ability of light sheet microscopy to maintain spatial resolution throughout relatively thick samples with the higher axial and spatial resolution characteristic of structured illumination microscopy. SI-LSM can achieve lateral resolution below 100 nm in biological samples hundreds of micrometers thick.
SI-LSM is most often used for fluorescent imaging of living biological samples, such as cell cultures. It is particularly useful for longitudinal studies, where high-rate imaging must be performed over long periods of time without damaging the sample. The two methods most used for fluorescent imaging of 3D samples – confocal microscopy and widefield microscopy – both have significant drawbacks for this type of application. In widefield microscopy, both in-focus light from the plane of interest as well as out-of-focus light from the rest of the sample is acquired together, creating the “missing cone problem” which makes high resolution imaging difficult. Although confocal microscopy largely solves this problem by using a pinhole to block unfocused light, this technique also inevitably blocks useful signal, which is particularly detrimental in fluorescent imaging when the signal is already very weak. In addition, both widefield and confocal microscopy illuminate the entirety of the sample throughout imaging, which leads to problems with photobleaching and phototoxicity in some samples. While light-field microscopy alone can address most of these issues, its achieved resolution is still fundamentally limited by the diffraction of light and it is unable to achieve super-resolution.
SI-LSM works by using a patterned rather than uniform light sheet to illuminate a single plane of a volume being imaged. In this way, it maintains the many benefits of light-sheet microscopy while achieving the high resolution of structured illumination microscopy.
Background and Theory
The theory behind SI-LSM is best understood by considering the separate development of structured illumination and light sheet microscopy.
Structured Illumination Microscopy
Structured illumination microscopy (SIM) is a method of super-resolution microscopy which is performed by acquiring multiple images of the same sample under different patterns of illumination, then computationally combining these images to achieve a single reconstruction with up to 2x improvement over the diffraction limited lateral resolution. The theory was first proposed and implemented in a 1995 paper by John M. Guerra in which a silicon grating with 50 nm lines and spaces was resolved with 650 nm wavelength (in air) illumination structured by a transparent replica proximal to said grating. The name “structured illumination microscopy” was coined in 2000 by M.G.L. Gustafsson. SIM takes advantage of the “Moiré Effect”, which occurs when two patterns are multiplicatively superimposed. The superimposition causes “Moiré Fringes” to appear, which are coarser than either original pattern but still contain information about the high frequency patterns which would otherwise not be visible.
The theory behind SIM is best understood in the Fourier or frequency domain. In general, imaging systems can only resolve frequencies below the diffraction limit. Thus, in the Fourier domain, all recorded frequencies from the imaged sample would reside within a circle of a fixed radius. Any frequencies outside this limit cannot be resolved. However, the frequency spectrum can be shifted by imaging the sample with patterned illumination. Most often, the pattern is a 1D sinusoidal gradient, such as the pattern used to create the Moiré fringes in the above image. Because the Fourier transform of a sinusoid is a shifted delta function, the transform of this pattern will consist of three delta functions: one at the zero frequency and two corresponding to the positive and negative frequency components of the sinusoid (see below image). When the target is illuminated using this pattern, the target and illumination pattern are multiplicatively superimposed, which means the Fourier transform of the resulting image is the convolution of the individual transforms of the target and the illumination pattern. Convolving any function with a delta function has the effect of shifting the center of the original function to the location of the delta function. Thus, in this situation, the frequency spectrum of the target is shifted and frequencies that were previously too high to resolve now lie within the circle of resolvable frequencies. The result is that for a single image acquisition with SIM, the frequency components from three separate regions in the Fourier domain (corresponding to the center and the positive and negative shifts) are all captured together. Finally, because rotation in the spatial domain results in the same rotation in the Fourier domain, high frequencies over the full 360° can be captured by rotating the illumination pattern. Figure b) in the image below shows which frequency components would be captured by acquiring 4 separate images and rotating the illumination pattern by 45° in between each acquisition.
Once all images have been captured, a single final image can be computationally reconstructed. Using this technique, resolution can be improved up to 2x over the diffraction limit. This 2x limit is imposed because the illumination pattern itself is still diffraction limited.
The concepts behind 2D SIM can be expanded to 3D volumetric imaging. By using three mutually coherent beams of excitation light, interference patterns with multiple frequency components can be created in the imaged sample. This ultimately makes it possible to perform 3D reconstructions with up to 2x improved resolution along all three axes. However, due to the strong scattering coefficient of biological tissues, this theoretical resolution can only be achieved in samples thinner than about 10 um. Beyond that, the scattering leads to an excess of background signal which makes accurate reconstruction impossible.
Light Sheet Microscopy
Light sheet microscopy (LSM) was developed to allow for fine optical sectioning of thick biological samples without the need for physical sectioning or clearing, which are both time consuming and detrimental to in-vivo imaging. While most fluorescent imaging techniques use aligned illumination and detection axes, LSM utilizes orthogonal axes. A focused light sheet is used to illuminate the sample from the side, while the fluorescent signal is detected from above. This both eliminates the “cone problem” of widefield microscopy by eliminating out-of-focus contributions from planes not being actively imaged and reduces the impact of photobleaching since the entire sample is not illuminated throughout imaging. In addition, because the sample is illuminated from the side, the focus of the illumination light is not depth-dependent, making volumetric imaging of biological samples far more feasible. A major ongoing challenge in LSM is in shaping the light sheet. In general, there is a tradeoff between the thickness of the light sheet at the optical axis (which largely determines axial resolution) and the field-of-view over which the light sheet maintains adequate thickness. This problem can be partially addressed by the added resolution from SI-LSM.
Techniques
SI-LSM can be divided into two main categories. Optical Sectioning SI-LSM is the most common approach and improves axial resolution by further reducing the impact of un-focused background signal. Super-resolution SI-LSM uses the illumination and reconstruction techniques of 2D SIM to achieve super-resolution in 3D samples.
Optical Sectioning SI-LSM
Optical sectioning SI-LSM (OS-SI-LSM) was first described in a 1997 paper by M.A. Neil et al. Rather than achieving super-resolution, this technique uses the ideas behind structured illumination to improve axial resolution by removing background haze from layers other than where the illuminating light sheet is most focused. While there are several approaches for achieving this, the most common approach is known as “three-phase” SIM, which will be described here.
It is shown in the Neil paper that the signal acquired by imaging a target with a grid illumination pattern can be represented by the following equation:
Here, is the background signal, while and are signals from the region of the target illuminated by the cosine and sine components of the grid. It is also shown that an in-focus image of the plane of interest could be reconstructed using the equation:
This can be achieved by acquiring three separate images under the grid illumination conditions, rotating the grid by 60° between each acquisition. The desired 2D image can then be reconstructed using the equation:
This creates a 2D image containing only information from most focused region of the grid illumination pattern. If this pattern is created using a light sheet, the sheet can then be scanned in the axial direction to generate a full 3D reconstruction of a sample. The primary drawback of using this approach for reducing background signal is that it ultimately relies on subtracting out the shared background signal between two images. Some in-focus signal will inevitably be subtracted alongside the background haze. This will result in an overall reduction of signal, which can be detrimental in low-signal fluorescent imaging. Nevertheless, this technique is the most common use of SI-LSM and has shown improved axial resolution over LSM alone.
Super-resolution SI-LSM
Super-resolution SI-LSM (SR-SI-LSM) uses the techniques from 2D or 3D SIM while using a light sheet as the illumination source to achieve the spatial resolution of SIM alongside the depth independent imaging and low photobleaching of LSM. In the most common application, a light sheet is used to create a 1D sinusoidal pattern at a single plane of the 3D target sample. The pattern is then rotated multiple times at this single plane to acquire enough images for a high resolution 2D reconstruction. The light is scanned in the axial resolution and the process is repeated until there are enough 2D images for a full 3D reconstruction. In general, this approach demonstrates not only improved resolution but also improved SNR over OS-SI-LSM, because no information is discarded in the reconstruction. In addition, although the theoretical resolution for SR-SI-LSM is slightly lower than 3D SIM, in depths >10 um this technique shows improved performance over 3D SIM due to the depth-independent focusing of illumination light characteristic of LSM.
Implementation
A major challenge in SI-LSM is engineering systems which are physically capable of generating structured patterns in light sheets. The three main approaches for accomplishing this are using interfering light sheets, digital LSM, and spatial light modulators.
With interfering light sheets, two coherent counterpropagating sheets are sent into the sample. The interference pattern between these sheets creates the desired illumination pattern, which can be rotated and scanned using rotating mirrors to deflect the sheets. Additional flexibility can be added by using digital light-sheet microscopy to generate the illumination patterns. In digital LSM, the light sheet is created by rapidly scanning a laser beam through the sample. This allows for fine control over the specific illumination pattern by modulating the intensity of the laser as it scans. This technique has been used to create systems capable of multiple types of light sheet microscopy in addition to SI-LSM. Finally, spatial light modulators can be used to electronically control the light patterns, which has the advantage of allowing for very fine control of and fast switching between patterns.
In addition, much of the recent work around SI-LSM focuses on combining the approach with other techniques for deep imaging in biological tissues. For instance, a 2021 paper demonstrated the use of SI-LSM with NIR-II illumination to improve resolution of transcranial mouse brain imaging by ~1.7x with a penetration depth of ~750 um and almost 16x improvement in the signal to background ratio. Other promising directions include combining SIM with other techniques for shaping the light sheets in LSM, combining SI-LSM with two-photon excitation, or using non-linear fluorescence to further push the resolution limits.
References
Microscopy
Optical imaging
Volumetric instruments | Structured illumination light sheet microscopy | [
"Chemistry",
"Technology",
"Engineering"
] | 2,391 | [
"Volumetric instruments",
"Measuring instruments",
"Microscopy"
] |
70,570,932 | https://en.wikipedia.org/wiki/Paul%20Dujardin%20%28engraver%29 | Paul Rodolphe Joseph Dujardin (; 13 June 1843 in Lille – 7 November 1913 in Paris) was a French engraver and photographer.
Biography
Son of Pierre-Antoine Dujardin, a doctor, he moved to Paris in 1875 to join his brother, Gustave Alexandre, who owned a photography studio. He specialized in plates, produced by rotogravure, and done in intaglio; taken from photographs.
He participated in the Exposition Universelle of 1878, where he presented earthenware, fabrics, and niellowork; made with a rotogravure process of his own devising. Later that year, he was named a Knight in the Legion of Honor. In 1879, he became a member of the Société française de photographie.
His store was on the , with a branch on the . He was also involved in making electrical accumulators and, together with his brothers, created "P. R. J. Dujardin et Cie". In 1890, he rented a turbine power plant on the Risle in Pont-Authou. His brother, Albert Désiré, was a builder of steam engines, and President of the Société française de photogravure, in 1900.
Publications
La Normandie monumentale et pittoresque, édifices publics, églises, châteaux, manoirs, etc., photographs by Émile-André Letellier and others, rotogravures by Paul Dujardin. Éditions Lemasle et Cie, Le Havre, 1893-1899, five volumes : Seine-Inférieure (1893), Calvados (1895), Eure (1896), Orne (1896) and Manche (1899)
References
External links
1843 births
1913 deaths
French engravers
Electrical equipment manufacturers
Artists from Lille | Paul Dujardin (engraver) | [
"Engineering"
] | 373 | [
"Electrical engineering organizations",
"Electrical equipment manufacturers"
] |
70,571,059 | https://en.wikipedia.org/wiki/Azov%20Lubricants%20and%20Oils | Azov Lubricants and Oils (AZMOL British Petrochemicals) is a petrochemical company located in Berdiansk, Zaporizhzhia Oblast. Today AZMOL British Petrochemicals is the largest producer of lubricants in Ukraine.
Awards
Order of the Red Banner
See also
XADO
WD-40
Carl Bechem GmbH
References
Companies established in 1937
Recipients of the Order of the Red Banner
Berdiansk
Companies based in Zaporizhzhia Oblast
Petrochemical companies
Petrochemical industry
1937 in Ukraine
History of Zaporizhzhia Oblast | Azov Lubricants and Oils | [
"Chemistry"
] | 128 | [
"Petrochemical industry"
] |
70,571,122 | https://en.wikipedia.org/wiki/Isolume | Isolumes are the preferred light zone of an organism in the ocean in the preferendum hypothesis. The preferendum hypothesis suggests that some organisms living in the mesopelagic zone, change their depth as light levels change in order to remain in their isolume. Organisms prefer to remain within a certain light level for a variety of reason. Some organisms, like Sergestidae, Euphausiid, and Palinuridae, use bioluminescence to camouflage their existence from predators and they change their depth as conditions change to stay in their isolume. Zooplankton in Arctic and Antarctic regions will remain at the same depth for months at a time due to the long winters with little to no daylight.
Organisms of the same species do not always exist in the same isolume and numerous factors can change what light levels an organism prefers to live within including age, sex, and competition for food.
References
Oceanography | Isolume | [
"Physics",
"Environmental_science"
] | 194 | [
"Oceanography",
"Hydrology",
"Applied and interdisciplinary physics"
] |
70,571,129 | https://en.wikipedia.org/wiki/Finite%20sphere%20packing | In mathematics, the theory of finite sphere packing concerns the question of how a finite number of equally-sized spheres can be most efficiently packed. The question of packing finitely many spheres has only been investigated in detail in recent decades, with much of the groundwork being laid by László Fejes Tóth.
The similar problem for infinitely many spheres has a longer history of investigation, from which the Kepler conjecture is most well-known. Atoms in crystal structures can be simplistically viewed as closely-packed spheres and treated as infinite sphere packings thanks to their large number.
Sphere packing problems are distinguished between packings in given containers and free packings. This article primarily discusses free packings.
Packing and convex hulls
In general, a packing refers to any arrangement of a set of spatially-connected, possibly differently-sized or differently-shaped objects in space such that none of them overlap. In the case of the finite sphere packing problem, these objects are restricted to equally-sized spheres. Such a packing of spheres determines a specific volume known as the convex hull of the packing, defined as the smallest convex set that includes all the spheres.
Packing shapes
There are many possible ways to arrange spheres, which can be classified into three basic groups: sausage, pizza, and cluster packing.
Sausage packing
An arrangement in which the midpoint of all the spheres lie on a single straight line is called a sausage packing, as the convex hull has a sausage-like shape. An approximate example in real life is the packing of tennis balls in a tube, though the ends must be rounded for the tube to coincide with the actual convex hull.
Pizza packing
If all the midpoints lie on a plane, the packing is a pizza packing. Approximate real-life examples of this kind of packing include billiard balls being packed in a triangle as they are set up. This holds for packings in three-dimensional Euclidean space.
Cluster packing
If the midpoints of the spheres are arranged throughout 3D space, the packing is termed a cluster packing. Real-life approximations include fruit being packed in multiple layers in a box.
Relationships between types of packing
By the given definitions, any sausage packing is technically also a pizza packing, and any pizza packing is technically also a cluster packing. In the more general case of dimensions, "sausages" refer to one-dimensional arrangements, "clusters" to -dimensional arrangements, and "pizzas" to those with an in-between number of dimensions.
One or two spheres always make a sausage. With three, a pizza packing (that is not also a sausage) becomes possible, and with four or more, clusters (that are not also pizzas) become possible.
Optimal packing
The empty space between spheres varies depending on the type of packing. The amount of empty space is measured in the packing density, which is defined as the ratio of the volume of the spheres to the volume of the total convex hull. The higher the packing density, the less empty space there is in the packing and thus the smaller the volume of the hull (in comparison to other packings with the same number and size of spheres).
To pack the spheres efficiently, it might be asked which packing has the highest possible density. It is easy to see that such a packing should have the property that the spheres lie next to each other, that is, each sphere should touch another on the surface. A more exact phrasing is to form a graph which assigns a vertex for each sphere and connects vertices with edges whenever the corresponding spheres if their surfaces touch. Then the highest-density packing must satisfy the property that the corresponding graph is connected.
Sausage catastrophe
With three or four spheres, the sausage packing is optimal. It is believed that this holds true for any up to along with . For and , a cluster packing exists that is more efficient than the sausage packing, as shown in 1992 by Jörg Wills and Pier Mario Gandini. It remains unknown what these most efficient cluster packings look like. For example, in the case , it is known that the optimal packing is not a tetrahedral packing like the classical packing of cannon balls, but is likely some kind of octahedral shape.
The sudden transition in optimal packing shape is jokingly known by some mathematicians as the sausage catastrophe (Wills, 1985). The designation catastrophe comes from the fact that the optimal packing shape suddenly shifts from the orderly sausage packing to the relatively unordered cluster packing and vice versa as one goes from one number to another, without a satisfying explanation as to why this happens. Even so, the transition in three dimensions is relatively tame; in dimensions the sudden transition is conjectured to happen around 377000 spheres.
For dimensions , the optimal packing is always either a sausage or a cluster, and never a pizza. It is an open problem whether this holds true for all dimensions. This result only concerns spheres and not other convex bodies; in fact Gritzmann and Arhelger observed that for any dimension there exists a convex shape for which the closest packing is a pizza.
Example of the sausage packing being non-optimal
In the following section it is shown that for 455 spheres the sausage packing is non-optimal, and that there instead exists a special cluster packing that occupies a smaller volume.
The volume of a convex hull of a sausage packing with spheres of radius is calculable with elementary geometry. The middle part of the hull is a cylinder with length while the caps at the end are half-spheres with radius . The total volume is therefore given by.
Similarly, it is possible to find the volume of the convex hull of a tetrahedral packing, in which the spheres are arranged so that they form a tetrahedral shape, which only leads to completely filled tetrahedra for specific numbers of spheres. If there are spheres along one edge of the tetrahedron, the total number of spheres is given by
.
Now the inradius of a tetrahedral with side length is
.
From this we have
.
The volume of the tetrahedron is then given by the formula
In the case of many spheres being arranged inside a tetrahedron, the length of an edge increases by twice the radius of a sphere for each new layer, meaning that for layers the side length becomes
.
Substituting this value into the volume formula for the tetrahedron, we know that the volume of the convex hull must be smaller than the tetrahedron itself, so that
.
Taking the number of spheres in a tetrahedron of layers and substituting into the earlier expression to get the volume of the convex hull of a sausage packing with the same number of spheres, we have
.
For , which translates to spheres the coefficient in front of is about 2845 for the tetrahedral packing and 2856 for the sausage packing, which implies that for this number of spheres the tetrahedron is more closely packed.
It is also possible with some more effort to derive the exact formula for the volume of the tetrahedral convex hull , which would involve subtracting the excess volume at the corners and edges of the tetrahedron. This allows the sausage packing to be proved non-optimal for smaller values of and therefore .
Sausage conjecture
The term sausage comes from the mathematician László Fejes Tóth, who posited the sausage conjecture in 1975, which concerns a generalized version of the problem to spheres, convex hulls, and volume in higher dimensions. A generalized sphere in dimensions is a -dimensional body in which every boundary point lies equally far away from the midpoint. Fejes Tóth's sausage conjecture then states that from upwards it is always optimal to arrange the spheres along a straight line. That is, the sausage catastrophe no longer occurs once we go above 4 dimensions. The overall conjecture remains open. The best results so far are those of Ulrich Betke und Martin Henk, who proved the conjecture for dimensions 42 and above.
Parametric density and related methods
While it may be proved that the sausage packing is not optimal for 56 spheres, and that there must be some other packing that is optimal, it is not known what the optimal packing looks like. It is difficult to find the optimal packing as there is no "simple" formula for the volume of an arbitrarily shaped cluster. Optimality (and non-optimality) is shown through appropriate estimates of the volume, using methods from convex geometry, such as the Brunn-Minkowski inequality, mixed Minkowski volumes and Steiner's formula. A crucial step towards a unified theory of both finite and infinite (lattice and non-lattice) sphere packings was the introduction of parametric densities by Jörg Wills in 1992. The parametric density takes into account the influence of the edges of the packing.
The definition of density used earlier concerns the volume of the convex hull of the spheres (or convex bodies) :
where is the convex hull of the midpoints of the spheres (instead of the sphere, we can also take an arbitrary convex body for ). For a linear arrangement (sausage), the convex hull is a line segment through all the midpoints of the spheres. The plus sign in the formula refers to Minkowski addition of sets, so that refers to the volume of the convex hull of the spheres.
This definition works in two dimensions, where Laszlo Fejes-Toth, Claude Rogers and others used it to formulate a unified theory of finite and infinite packings. In three dimensions, Wills gives a simple argument that such a unified theory is not possible based on this definition: The densest finite arrangement of coins in three dimensions is the sausage with . However, the optimal infinite arrangement is a hexagonal arrangement with , so the infinite value cannot be obtained as a limit of finite values. To solve this issue, Wills introduces a modification to the definition by adding a positive parameter :
allows the influence of the edges to be considered (giving the convex hull a certain thickness). This is then combined with methods from the theory of mixed volumes and geometry of numbers by Hermann Minkowski.
For each dimension there are parameter values and such that for the sausage is the densenst packing (for all integers ), while for and suffiricently large the cluster is densest. These parameters are dimension-specific. In two dimensions, so that there is a transition from sausages to clusters (sausage catastrophe).
There holds an inequality:
where the volume of the unit ball in dimensions is . For , we have and it is predicted that this holds for all dimensions, in which case the value of can be found from that of .
References
Euclidean solid geometry | Finite sphere packing | [
"Physics"
] | 2,140 | [
"Spacetime",
"Space",
"Euclidean solid geometry"
] |
70,571,676 | https://en.wikipedia.org/wiki/Hafnocene%20dichloride | Hafnocene dichloride is the organohafnium compound with the formula . It is a white solid that is sparingly soluble in some organic solvents. The lighter homologues zirconacene dichloride and titanocene dichloride have received much more attention. While hafnocene is only of academic interest, some more soluble derivatives are precatalysts for olefin polymerization. Moreso than the Zr analogue, this compound is highly resistant to reduction.
It is prepared by a salt metathesis reaction from hafnium tetrachloride by salt metathesis:
Derivatives
Hydrolysis gives the trimer .
The chloride ligands can be replaced by other halides.
The bis(phosphide) can be prepared by salt metathesis from hafnocene dichloride.
References
Metallocenes
Chloro complexes
Cyclopentadienyl complexes
Hafnium compounds | Hafnocene dichloride | [
"Chemistry"
] | 194 | [
"Organometallic chemistry",
"Cyclopentadienyl complexes"
] |
70,572,359 | https://en.wikipedia.org/wiki/Boris%20B.%20Zvyagin | Boris Borisovich Zvyagin (April 14, 1921 – September 18, 2002) was a Russian mineralogist and crystallographer. He is a pioneer in the structural study of layer minerals by electron diffraction and is also known for his work on modular structures, including polymorphism, polytypism, and order-disorder structures in crystals.
Zvyagin attended Moscow State University without entrance exams, graduating with a degree in physics in 1944. He worked at the All-Union Geological Institute since 1949 and was awarded doctor of science in 1963 at the Moscow Soil Institute. He then moved to the Institute of Ore Mineralogy of the Russian Academy of Sciences, heading the laboratory there. Zvyagin became a professor of crystallography and mineralogy in 1977 at the Russian Academy of Sciences.
Zvyagin was awarded the Bailey Distinguished Member Award by The Clay Minerals Society in 2000.
Bibliography
References
1921 births
2002 deaths
Crystallographers
Russian mineralogists
Moscow State University alumni
Members of the Russian Academy of Sciences | Boris B. Zvyagin | [
"Chemistry",
"Materials_science"
] | 210 | [
"Crystallographers",
"Crystallography"
] |
70,572,808 | https://en.wikipedia.org/wiki/Tertiary%20review | In software engineering, a tertiary review is a systematic review of systematic reviews. It is also referred to as a tertiary study in the software engineering literature. However, Umbrella review is the term more commonly used in medicine.
Kitchenham et al. suggest that methodologically there is no difference between a systematic review and a tertiary review. However, as the software engineering community has started performing tertiary reviews new concerns unique to tertiary reviews have surfaced. These include the challenge of quality assessment of systematic reviews, search validation and the additional risk of double counting.
Examples of Tertiary reviews in software engineering literature
Test quality
Machine Learning
Test-driven development
References
Software engineering
Meta-analysis | Tertiary review | [
"Technology",
"Engineering"
] | 132 | [
"Software engineering",
"Systems engineering",
"Information technology",
"Computer engineering"
] |
70,573,417 | https://en.wikipedia.org/wiki/Leray%E2%80%93Schauder%20degree | In mathematics, the Leray–Schauder degree is an extension of the degree of a base point preserving continuous map between spheres or equivalently to boundary-sphere-preserving continuous maps between balls to boundary-sphere-preserving maps between balls in a Banach space , assuming that the map is of the form where is the identity map and is some compact map (i.e. mapping bounded sets to sets whose closure is compact).
The degree was invented by Jean Leray and Juliusz Schauder to prove existence results for partial differential equations.
References
Topology | Leray–Schauder degree | [
"Physics",
"Mathematics"
] | 115 | [
"Topology stubs",
"Topology",
"Space",
"Geometry",
"Spacetime"
] |
70,573,971 | https://en.wikipedia.org/wiki/Megogo | Megogo (stylized as MEGOGO) (Ukrainian: Мегого) is an international OTT/VOD service based in Kyiv, Ukraine. It is the largest entertainment service in Eastern Europe with over 55 million users and a catalog of about 200 thousand hours of content: movies and documentaries, cartoons, series, TV programs and shows, sports broadcasts and cultural events, travel-shows, football matches, audiobooks, podcasts etc. It also provides streams of over 4000 local and foreign TV channels. FOX, Universal, Sony, Walt Disney, MGM, Miramax, Warner Brothers, Paramount Pictures, Blue Ant Media, Euronews, Discovery Communications, Scripps, Viacom. It is among the exclusive broadcasters of European football leagues La Liga, Ligue 1, Serie A, etc.
In July 2020, MEGOGO started the production of audiobooks, mostly modern Ukrainian literature and soon, in 2021, began to produce exclusive audio series.
In January 2021, MEGOGO announced that it had become the exclusive broadcaster of the UEFA Champions League, UEFA Europa League and UEFA Conference League matches for the 2021–2024 seasons in Ukraine.
Also in 2021, MEGOGO launched its own voice acting studio "MEGOGO Voice" with a focus on Ukrainian language.
History
The service launched officially on November 22, 2011, in Kyiv, Ukraine. In March 2012, the number of visitors of the website hit 4.5 million. In April of the same year, the site of online movie theater was adapted for watching videos on iPod, iPhone and iPad devices.
In May 2012, MEGOGO opened offices in Belarus and Latvia. In June 2012, free access to MEGOGO was made available in the LG TVs with Smart TV. Also, the embedded video-player was created, which can be placed on any site and social network.
In November 2012, MEGOGO apps were launched for Panasonic's Smart Viera TVs and in the Windows Store. At this point the monthly number of users has reached 13 million. In January 2013, the monthly audience hit 17.5 million, and in February it reached 20 million.
In the beginning of 2014, MEGOGO has launched the TV section, where the broadcast of linear channels is streamed. In February 2015, the number of monthly unique users reached 32 million, when the service started streaming 4K content.
In 2015, MEGOGO launched the Pay TV. In May 2016, it began creating its own content. For example, a 28-episode cartoon series about the Cossacks.
At the end of 2015, it was launched virtual reality app for watching movies, which works on some models of mobile devices
In July 2016, appeared the MEGOGO LIVE direction, which was engaged exclusively in live broadcasts of sport and cultural events. In 2018, the project was completely reformatted and was replaced by the youth music channel MEGOGO LIVE.
In October 2016, MEGOGO launched the social initiative «Look as you hear» (укр.Дивись як чутно), that creates opportunities to view the world's best content for viewers with hearing impairments, adding sign language translation, as well as visual impairments, creating typhlocomments. All inclusive content is collected in a separate section. Also two separate interactive channels «Look as you hear» and «Cinema Sounds» were created.
In early 2019, on the platform appeared the sports channel – MEGOGO Football, which broadcasts matches and reviews of European championships: La Liga, Liga 1, Bundesliga, Premier League.
In December 2019, the company launched a new lineup, MEGOGO Audio, which offers audiobooks and podcasts. In May 2020, the media service opened the possibility for podcasters to download their own audio files. By now, in 2022, the section has more than 12 000 episodes of podcasts and more than 2000 fairytales for kids.
At the end of 2019, the company broadened the range of its activities to become a mediaservice for the whole family. Before MEGOGO has positioned itself as a video service of movies, series, cartoons, shows and TV. Currently the company has launched its own channels, audio content with podcasts and audiobooks, and creates its own content.
In 2020, Discovery and MEGOGO announced a partnership. As part of the cooperation, subscribers received access to the content of the Discovery+ online entertainment service.
In July 2020, MEGOGO signed a memorandum of cooperation with the Ministry of Digital Transformation of Ukraine.
In February 2021, the platform began creating audio series, the first of which tells about the Kureniv tragedy in Kyiv. There are currently 12 audio series available on the service.
As of February 2022, MEGOGO is the exclusive broadcaster in Ukraine of such sports events: matches of the UEFA Champions League, UEFA Europa League and UEFA Conference League, La Liga, Ligue 1, DFB-Pokal, Copa América and Brazilian Championship A Series, Top Rank fights, K2 Promotions Ukraine, Bellator and much more.
In February 2022, MEGOGO removed all Russian-made content and closed access to the service in Russia, suspending any of the Russian Federation.
Later, in April 2022, the company launched a new business-unit – MEGOGO Outsourcing. Now MEGOGO can provide its services to external companies in the areas of IT, live broadcasts, production etc.
In 2023, Megogo expanded its offer into Poland and Romania, providing popular TV channels through hybrid television.
Сontent
Content is available in many languages, including Ukrainian, English, German, French, Latvian, Lithuanian, Estonian, Georgian, Turkish, Polish, Romanian etc.
In February 2013, the company signed a contract with the BBC and purchased 300 hours of video production, including the documentary “Planet of the Humans”, David Attenborough's “Frozen Planet”, and series “Luther”, “Sherlock”, and “Ghosts”.
In May 2016, MEGOGO started to create its own content.
In July 2020, service began the production of audiobooks, the first collections of short prose «Maybe Tomorrow» and «Abyss» by Ukrainian writer and director Marisa Nikityuk, voiced by the author.
In the fall of 2020, service announced the production of the series in partnership with 1+1 media. In December 2021, MEGOGO hosted a culinary show of its own production "Queen of the Kitchen" with host Olya Polyakova. Also in December MEGOGO released its own music and entertainment New Year's show with the participation of Ukrainian stars.
In 2020, the service announced the acquisition of exclusive rights to show the events of the American boxing promotion company Top Rank in Ukraine. Subsequently, MEGOGO began a strategic partnership with K2 Promotions Ukraine, founded by the Klitschko brothers. To viewers became available exclusive broadcasts of fights with the participation of Ukrainian titled professional boxers.
MEGOGO is developing sports direction and has a number of exclusive events. In January 2021, the company had received the rights from UEFA to show the seasons of the UEFA Champions League, the UEFA Europa League and the UEFA Conference League until 2024. For the first time in the history of Ukraine, the tender for showing matches of European clubs was won by OTT-service.
References
External links
Megogo Official website
Streaming television
Smart TV
Mass media companies of Ukraine
Companies based in Kyiv
Mass media companies established in 2011
Entertainment companies established in 2011
2011 establishments in Ukraine
Internet properties established in 2011 | Megogo | [
"Technology"
] | 1,514 | [
"Multimedia",
"Smart TV"
] |
70,574,438 | https://en.wikipedia.org/wiki/Internal%20border%20control | Controls imposed on internal borders within a single state or territory include measures taken by governments to monitor and regulate the movement of people, animals, and goods across land, air, and maritime borders through border controls.
Background
Internal border controls are measures implemented to control the flow of people or goods within a given country. Such measures take a variety of forms ranging from the imposition of border checkpoints to the issuance of internal travel documents and vary depending on the circumstances in which they are implemented. Circumstances resulting in internal border controls include increasing security around border areas (e.g. internal checkpoints in America or Bhutan near border regions), preserving the autonomy of autonomous or minority areas (e.g. border controls between Peninsular Malaysia, Sabah, and Sarawak; border controls between Hong Kong, Macau, and mainland China), preventing unrest between ethnic groups (e.g. Northern Ireland's peace walls, border controls in Tibet and Northeastern India), and disputes between rival governments (e.g. between the Republic of China and the People's Republic of China).
During the COVID-19 pandemic, temporary internal border controls were introduced in jurisdictions across the globe. For instance, travel between Australian states and territories was prohibited or restricted by state governments at various points of the pandemic either in conjunction with sporadic lockdowns or as a stand-alone response to COVID-19 outbreaks in neighbouring states. Internal border controls were also introduced at various stages of Malaysia's Movement Control Order, per which interstate travel was restricted depending on the severity of ongoing outbreaks. Similarly, internal controls were introduced by national authorities within the Schengen Area, though the European Union ultimately rejected the idea of suspending the Schengen Agreement per se.
Examples
Asia
Internal border controls exist in many parts of Asia. For example, travellers visiting minority regions in India and China often require special permits to enter.
India
Permits issued for minority regions in India include:
Restricted Area Permits and Protected Area Permits for foreigners in portions of north-eastern India and the Andaman and Nicobar Islands
Inner Line Permits for Indian citizens
China
In the Tibet Autonomous Region (Tibetan: བོད་རང་སྐྱོང་ལྗོངས།; ), two categories of permits are issued:
The Tibet Travel Permits ( foreigners' entrance letter) required for all foreigners (as well as Taiwanese nationals from the Republic of China) to enter the region
The Alien Travel Permit required for holders of the Tibet Travel Permit to travel outside major urban and tourist areas of the region
The Military Permit (or Border Permit) is required for travel to Ngari (Tibetan: མངའ་རིས་ས་ཁུལ་; ), Nyingchi (Tibetan: ཉིང་ཁྲི་ས།; ), and Nagqu (Tibetan: ནག་ཆུ།; )
Additionally, special permits are issued to nationals of India and Bhutan for religious pilgrimages to Hindu and Buddhist holy sites in the Tibet Autonomous Region. Internal air and rail travel within non-autonomous portions of India and mainland China also generally require travel documents to be checked by government officials as a form of the interior border checkpoint. For such travel within India, Indian citizens may utilise their Voter ID, National Identity Card, passport, or other proof of Indian citizenship whilst Nepali nationals may present any similar proof of Nepali citizenship. Meanwhile, for such travel within mainland China, Chinese nationals from the mainland are required to use their national identity cards.
Within China, extensive border controls are maintained for those travelling between the mainland, special administrative regions of Hong Kong and Macau. Foreign nationals need to present their passports or other required types of travel documents when travelling between these jurisdictions. For Chinese nationals (including those with British National (Overseas) status), there are special documents for travel between these territories. Internal border controls in China have also resulted in the creation of special permits allowing Chinese citizens to immigrate to or reside in other immigration areas within the country.
China also maintains distinct, relaxed border control policies in the Special Economic Zones of Shenzhen, Zhuhai and Xiamen. Nationals of most countries can obtain a limited area visa upon arrival in these regions, which permit them to stay within these cities without proceeding further into other parts of Mainland China. Visas for Shenzhen are valid for 5 days, and visas for Xiamen and Zhuhai are valid for 3 days. The duration of stay starts from the next day of arrival. The visa can only be obtained only upon arrival at Luohu Port, Huanggang Port Control Point, Fuyong Ferry Terminal or Shekou Passenger Terminal for Shenzhen; Gongbei Port of Entry, Hengqin Port or Jiuzhou Port for Zhuhai; and Xiamen Gaoqi International Airport for Xiamen.
Similarly, China permits nationals of non—visa-exempt ASEAN countries to visit Guilin without a visa for a maximum of 6 days if they travel with an approved tour group and enter China from Guilin Liangjiang International Airport. They may not visit other cities within Guangxi or other parts of Mainland China.
Neither the People's Republic of China nor the Republic of China recognizes the passports issued by the other and neither considers travel between mainland China and areas controlled by the Republic of China
as formal international travel. There are arrangements exist for travel between territories controlled by the Republic of China and territories controlled by the People's Republic of China.
More generally, authorities in mainland China maintain a system of residency registration known as hukou (), by which government permission is needed to formally change one's place of residence. It is enforced with identity cards. This system of internal border control measures effectively limited internal migration before the 1980s but subsequent market reforms caused it to collapse as a means of migration control. An estimated 150 to 200 million people are part of the "blind flow" and have unofficially migrated, generally from poor, rural areas to wealthy, urban ones. However, unofficial residents are often denied official services such as education and medical care and are sometimes subject to both social and political discrimination. In essence, the denial of social services outside an individual's registered area of residence functions as an internal border control measure geared toward dissuading migration within the mainland.
Bhutan
Meanwhile, in Bhutan, a microstate accessible by road only through India, there are interior border checkpoints (primarily on the Lateral Road) and, additionally, certain areas require special permits to enter, whilst visitors not proceeding beyond the border city of Phuentsholing do not need permits to enter for the day (although such visitors are de facto subject to Indian visa policy since they must proceed through Jaigaon). Individuals who are not citizens of India, Bangladesh, or the Maldives must obtain both their visa and any regional permits required through a licensed tour operator prior to arriving in the country. Citizens of India, Bangladesh, and the Maldives may apply for regional permits for restricted areas online.
Vietnam
The Hộ khẩu system in Vietnam is similar to the Hukou system in mainland China. Local authorities issue each household a "household registration book" or sổ hộ khẩu, in which the basic biographical information of each household member is recorded. The sổ hộ khẩu is the ultimate legal proof of residence in Vietnam. Together with the "citizen identification card" or giấy chứng minh nhân dân/căn cước công dân, the sổ hộ khẩu constitutes the most important legal identification document in Vietnam. Modelled after the Chinese hukou system and originally used in urban areas only, hộ khẩu functioned as a way to manage urban growth and limit how many people moved, as well as who moved in and out of the cities. Gradually, the system became a universal method of control as its application expanded to the countryside. Presently, the system defines four types of residence, KT1 through KT4. KT1 is the primary and permanent type of residence and denotes a person's primary residential address. People moving on a semi-permanent basis to another place within the same province or national municipality (within Saigon, for example) need to register for a KT2 residential status at that new address. If this same move happens across provincial borders, then the person has to sign up for a KT3 registration. For migrant workers and students temporarily residing outside of their province or national municipality of permanent residence, they need to apply for a KT4 registration. Navigating this matrix of regulations is tough. But the public security apparatus that manages the hộ khẩu system is also difficult to deal with, especially if one is a poor migrant worker with little to no formal education. Yet hộ khẩu remains absolutely crucial, especially for the poor. It is tied to access to welfare benefits, and, in the case of children, the right to attend public school. For a migrant family in Saigon with no KT3 or KT4 registration, subsidised medical care, poverty assistance, and almost-free schooling are all out of reach. Much like its counterpart in mainland China, the denial of services outside an individual's place of registered residence resulting from this system of internal border control serves to dissuade internal migration.
Malaysia
Another example is the Malaysian states of Sabah and Sarawak, which have maintained their own border controls since joining Malaysia in 1963. The internal border control is asymmetrical; while Sabah and Sarawak impose immigration control on Malaysian citizens from other states, there is no corresponding border control in Peninsular Malaysia, and Malaysians from Sabah and Sarawak have unrestricted right to live and work in the Peninsular. For social and business visits less than three months, Malaysian citizens may travel between the Peninsular, Sabah and Sarawak using the Malaysian identity card (MyKad) or Malaysian passport, while for longer stays in Sabah and Sarawak they are required to have an Internal Travel Document or a passport with the appropriate residential permit.
North Korea
The most restrictive internal border controls are in North Korea. Citizens are not allowed to travel outside their areas of residence without explicit authorisation, and access to the capital city of Pyongyang is heavily restricted. Similar restrictions are imposed on tourists, who are only allowed to leave Pyongyang on government-authorised tours to approved tourist sites.
Israel
The Israeli military maintains an intricate network of internal border controls within Israeli and Palestinian territory restricting the freedom of movement of Palestinians, composed of permanent, temporary, and random manned checkpoints in the West Bank; the West Bank Barrier; and restrictions on the usage of roads by Palestinians. Spread throughout the State of Israel and the areas of the State of Palestine under de facto Israeli control, internal border control measures are a key feature of Israeli and Palestinian life and are among the most restrictive in the world. Additionally, the blockade of the Gaza Strip results in a de facto domestic customs and immigration border for Palestinians. In order to clear internal border controls, Palestinians are required to obtain a variety of permits from Israeli authorities depending on the purpose and area of their travel. The legality and impact of this network of internal border controls is controversial. B'Tselem, an Israeli non-governmental organisation that monitors human rights in Palestine, argues that they breach the rights guaranteed by the International Covenant on Economic, Social and Cultural Rights—in particular, the right to a livelihood, the right to an acceptable standard of living, the right to satisfactory nutrition, clothing, and housing, and the right to attain the best standard of physical and mental health. B'Tselem also argues that the restrictions on ill, wounded and pregnant Palestinians seeking acute medical care is in contravention of international law that states that medical professionals and the sick must be granted open passage. While Israeli Supreme Court has deemed the measures acceptable for security reasons, Haaretzs Amira Hass argues this policy defies one of the principles of the Oslo Accords, which states that Gaza and the West Bank constitute a single geographic unit.
Gallery
Europe
An example from Europe is the implementation of border controls on travel between Svalbard, which maintains a policy of free migration as a result of the Svalbard Treaty and the Schengen Area, which includes the rest of Norway. Other examples of effective internal border controls in Europe include the closed cities of certain CIS members, areas of Turkmenistan that require special permits to enter, restrictions on travel to the Gorno-Badakhshan Autonomous Region in Tajikistan, and (depending on whether Northern and Southern Cyprus are considered separate countries) the Cypriot border. Similarly, Iraq's Kurdistan region maintains a separate and more liberal visa and customs area from the rest of the country, even allowing visa free entry for Israelis whilst the rest of the country bans them from entering. Denmark also maintains a complex system of subnational countries which, unlike the Danish mainland, are outside the European Union and maintain autonomous customs policies. In addition to the numerous closed cities of Russia, parts of 19 subjects of the Russian Federation are closed for foreigners without special permits and are consequently subject to internal border controls.
United Kingdom
Another complex border control situation in Europe pertains to the United Kingdom. Whilst the crown dependencies are within the Common Travel Area, neither Gibraltar nor the sovereign British military exclaves of Akrotiri and Dhekelia are. The former maintains its own border control policies, thus requiring physical border security at its border with the Schengen Area as well as the implementation of border controls for travellers proceeding directly between Gibraltar and the British mainland. The latter maintains a relatively open border with Southern Cyprus, though not with Northern Cyprus. Consequently, it is a de facto member of the Schengen Area and travel to or from the British mainland requires border controls. On 31 December 2020, Spain and the United Kingdom reached an agreement in principle under which Gibraltar would join the Schengen Area, clearing the way for the European Union and the UK to start formal negotiations on the matter.
In the aftermath of Brexit, border controls for goods flowing between Great Britain and Northern Ireland were introduced in accordance with the Protocol on Ireland/Northern Ireland agreed to as part of the UK's withdrawal agreement with the EU. Due to the thirty-year internecine conflict in Northern Ireland, the UK-Ireland border has had a special status since that conflict was ended by the Belfast Agreement/Good Friday Agreement of 1998. As part of the Northern Ireland Peace Process, the border has been largely invisible, without any physical barrier or custom checks on its many crossing points; this arrangement was made possible by both countries' common membership of both the EU's Single Market and Customs Union and of their Common Travel Area. Upon the UK's withdrawal from the European Union, the border in Ireland became the only land border between the UK and EU. EU single market and UK internal market provisions require certain customs checks and trade controls at their external borders. The Northern Ireland Protocol is intended to protect the EU single market, while avoiding imposition of a 'hard border' that might incite a recurrence of conflict and destabilise the relative peace that has held since the end of the Troubles. Under the Protocol, Northern Ireland is formally outside the EU single market, but EU free movement of goods rules and EU Customs Union rules still apply; this ensures there are no customs checks or controls between Northern Ireland and the rest of the island. In place of an Ireland/Northern Ireland land border, the protocol has created a de facto customs border down the Irish Sea for customs purposes, separating Northern Ireland from the island of Great Britain, to the disquiet of prominent Unionists. To operate the terms of the protocol, the United Kingdom must provide border control posts at Northern Ireland's ports: actual provision of these facilities is the responsibility of Northern Ireland's Department of Agriculture, Environment and Rural Affairs (DAERA). Temporary buildings were put in place for 1 January 2021, but in February 2021, the responsible Northern Ireland minister, Gordon Lyons (DUP), ordered officials to stop work on new permanent facilities and to stop recruiting staff for them. In its half yearly financial report 26 August 2021, Irish Continental Group, which operates ferries between Great Britain and the Republic of Ireland, expressed concern at the lack of implementation of checks on goods arriving into Northern Ireland from Great Britain, as required under the protocol. The company said that the continued absence of these checks (on goods destined for the Republic of Ireland) is causing a distortion in the level playing field, since goods that arrive directly into Republic of Ireland ports from Great Britain are checked on arrival. The implementation of border controls between Great Britain and Northern Ireland was the primary catalyst for the 2021 Northern Ireland riots.
Peace lines
Much like relations between Jewish settlers in Israel and the native Palestinian population, strained intercommunal relations in Northern Ireland between Irish Catholics and the descendants of Protestant settlers from England and Scotland have resulted in de facto internal checkpoints. The peace lines are an internal border security measure to separate predominantly republican and nationalist Catholic neighbourhoods from predominantly loyalist and unionist Protestant neighbourhoods. They have been in place in some form or another since the end of The Troubles in 1998, with the Good Friday Agreement. The majority of peace walls are located in Belfast, but they also exist in Derry, Portadown, and Lurgan, with more than 32 kilometres of walls in Northern Ireland. The peace lines range in length from a few hundred metres to over 5 kilometres. They may be made of iron, brick, steel or a combination of the three and are up to 8 metres high. Some have gates in them (sometimes staffed by police) that allow passage during daylight but are closed at night.
Schengen Area
An unusual example of internal border controls pertains to customs enforcement within the Schengen area. Even though borders are generally invisible, the existence of areas within the Schengen area but outside the European Union Value Added Tax Area, as well as jurisdictions such as Andorra which are not officially a part of the Schengen area but can not be accessed without passing through it, has resulted in the existence of sporadic internal border controls for customs purposes. Additionally, as per Schengen area rules, hotels and other types of commercial accommodation must register all foreign citizens, including citizens of other Schengen states, by requiring the completion of a registration form by their own hand. The Schengen rules do not require any other procedures; thus, the Schengen states are free to regulate further details on the content of the registration forms, and identity documents which are to be produced, and may also require the persons exempted from registration by Schengen laws to be registered. A Schengen state is also permitted to reinstate border controls with another Schengen country for a short period where there is a serious threat to that state's "public policy or internal security" or when the "control of an external border is no longer ensured due to exceptional circumstances". When such risks arise out of foreseeable events, the state in question must notify the European Commission in advance and consult with other Schengen states. Since the implementation of the Schengen Agreement, this provision has been invoked frequently by member states, especially in response to the European migrant crisis.
Gallery
North America
Contemporary
Multiple types of internal border controls exist in the United States. While the American territories of Guam and the Northern Mariana Islands follow the same visa policy as the mainland, together, they also maintain their own visa waiver programme for certain nationalities. Since the two territories are outside the customs territory of the United States, there are customs inspections when travelling between them, and the rest of the U.S. American Samoa has its own customs and immigration regulations, thus travelling between it and other American jurisdictions involves both customs and immigration inspections. The Virgin Islands are a special case, falling within the American immigration zone and solely following American visa policy, but being a customs free territory. As a result, there are no immigration checks between the two, but travellers arriving in Puerto Rico or the American mainland directly from the Virgin Islands are subject to border control for customs inspection. The United States also maintains interior checkpoints, similar to those maintained by Bhutan, along its borders with Mexico and Canada, subjecting people to border controls even after they have entered the country.
The Akwesasne nation; with territory in Ontario, Quebec, and New York; features several de facto internal border controls. As a result of protests by Akwesasne residents on their rights to cross the border unimpeded, as provided under the 1795 Jay Treaty, the Canada Border Services Agency closed its post on Cornwall Island, instead requiring travellers to proceed to the checkpoint in the city of Cornwall. As a consequence of the arrangement, residents of the island are required to clear border controls when proceeding North to the Ontarian mainland, as well as when proceeding South to Akwesasne territory in New York, thus constituting internal controls both from a Canadian perspective and from the perspective of the Akwesasne nation. Similarly, travelling between Canada and the Quebec portion of the Akwesasne nation requires driving through the state of New York, meaning that individuals will be required to clear American controls when leaving Quebec proper and to clear Canadian border controls when entering Quebec proper, though Canada does not impose border controls when entering the Quebec portion of the Akwesasne nation. Nevertheless, for residents who assert a Haudenosaunee national identity distinct from Canadian or American citizenship, the intricate network of Canadian and American border controls are seen as a foreign-imposed system of internal border controls, similar to the Israeli checkpoints in Palestinian territory.
The city of Hyder, Alaska has also been subject to internal border controls since America chose to stop regulating arrivals in Hyder from British Columbia. Since travellers exiting Hyder into Stewart, British Columbia are subject to Canadian border controls, it is theoretically possible for someone to accidentally enter Hyder from Canada without their travel documents and then to face difficulties since both America and Canada would subject them to border controls that require travel documents. At the same time, however, the northern road connecting Hyder to uninhabited mountain regions of British Columbia is equipped with neither American nor Canadian border controls, meaning that tourists from Canada proceeding northwards from Hyder are required to complete Canadian immigration formalities when they return to Stewart despite never having cleared American immigration.
Historical
In the past, internal border control measures were utilised by authorities in North America to control the movements of Indigenous or enslaved persons. Such systems typically took the form of an internal passport required for Indigenous or enslaved individuals to travel beyond their reserve or plantation.
In 1885 the "pass system" of internal border controls targeting Indigenous peoples was instituted in Canada. Introduced at the time of the North-West Rebellion, it remained in force until 1951. Any Indigenous person caught outside his Indian reserve without a pass issued by an Indian agent was returned to the reserve or incarcerated.
Throughout the Thirteen Colonies before the Revolutionary War, slaves confined to homes or agricultural plantations, or whose movements were limited by curfews, could be required to furnish written evidence their owner had granted an exemption to permit their free movement. For example, the New Hampshire Assembly in 1714 passed "An Act To Prevent Disorders In The Night": Notices emphasizing the curfew were published in The New Hampshire Gazette in 1764 and 1771.
Internal passports were required for African Americans in the southern slave states before the American Civil War, for example, an authenticated internal passport dated 1815 was presented to Massachusetts citizen George Barker to allow him to freely travel as a free black man to visit relatives in slave states. After many of these states seceded, forming the Confederate States of America, the Confederate government introduced internal passports for whites as well.
Realm of New Zealand
Tokelau, Niue, and the Cook Islands (Cook Islands Māori: Kūki 'Āirani) maintain independent and less restrictive border controls from New Zealand. The Cook Islands further maintain a separate nationality law. Additionally, border controls for Tokelau are complicated by the fact that the territory is, for the most part, only accessible via Samoa.
Apartheid-era South Africa
In South Africa prior to the end of Apartheid, pass laws were a form of internal passport system designed to segregate the population, manage urbanisation, and allocate migrant labour. Also known as the natives' law, pass laws severely limited the movements of not only black African citizens, but other people as well by requiring or designated areas. Before the 1950s, this legislation largely applied to African men, and attempts to apply it to women in the 1910s and 1950s were met with significant protests. Pass laws were one of the dominant features of the country's apartheid system until it was effectively ended in 1986. The first internal passports in South Africa were introduced on 27 June 1797 by the Earl Macartney in an attempt to prevent Africans from entering the Cape Colony. The Cape Colony was merged with the two Afrikaners republics in southern Africa to form the Union of South Africa in 1910. By this time, versions of pass laws existed elsewhere. A major boost for their utilization was the rise of the mining sector from the 1880s: pass laws provided a convenient means of controlling workers' mobility and enforcing contracts. In 1896 the South African Republic brought in two pass laws which required Africans to carry a metal badge. Only those employed by a master were permitted to remain on the Rand. Those entering a "labour district" needed a special pass which entitled them to remain for three days. The Natives (Urban Areas) Act of 1923 deemed urban areas in South Africa as "white" and required all black African men in cities and towns to carry around permits called "passes" at all times. Anyone found without a pass would be arrested immediately and sent to a rural area. It was replaced in 1945 by the Natives (Urban Areas) Consolidation Act, which imposed "influx control" on black men and also set up guidelines for removing people deemed to be living idle lives from urban areas. This act outlined requirements for African peoples' "qualification" to reside legally in white metropolitan areas. To do so, they had to have Section 10 rights, based on whether
the person had been born there and resided there always since birth;
the person had laboured continuously for ten years in any agreed area for any employer, or lived continuously in any such area for fifteen years;
The Black (Natives) Laws Amendment Act of 1952 amended the 1945 Native Urban Areas Consolidation Act, stipulating that all black people over the age of 16 were required to carry passes and that no black person could stay in an urban area more than 72 hours unless allowed to by Section 10. The Natives (Abolition of Passes and Co-ordination of Documents) Act of 1952, commonly known as the Pass Laws Act, repealed the many regional pass laws and instituted one nationwide pass law, which made it compulsory for all black South Africans over the age of 16 to carry the "passbook" at all times within white areas. The law stipulated where, when, and for how long a person could remain.
The document was similar to an internal passport, containing details on the bearer such as their fingerprints, photograph, the name of his/her employer, his/her address, how long the bearer had been employed, as well as other identification information. Employers often entered a behavioural evaluation, on the conduct of the pass holder. An employer was defined under the law and could only be a white person. The pass also documented permission requested and denied or granted to be in a certain region and the reason for seeking such permission. Under the terms of the law, any government employee could strike out such entries, basically cancelling the permission to remain in the area. A passbook without a valid entry then allowed officials to arrest and imprison the bearer of the pass. These passes often became the most despised symbols of apartheid. The resistance to the Pass Law led to many thousands of arrests and was the spark that ignited the Sharpeville Massacre on 21 March 1960, and led to the arrest of Robert Sobukwe that day.
See also
Border barrier
Airspace
Air sovereignty
Illegal entry
United States Border Patrol
Security guard
Illegal immigration
Immigration law
Maritime boundary
Freedom of movement
Refugees
Notes
References
Further reading
Susan Harbage Page & Inéz Valdez (17 April 2011). "Residues of Border Control", Southern Spaces
Philippe Legrain (2007). Immigrants: Your Country Needs Them, Little Brown,
Aristide Zolberg (2006). A Nation by Design: Immigration Policy in the Fashioning of America, Harvard University Press,
Philippe Legrain (2007). Immigrants: Your Country Needs Them, Little Brown,
Ruben Rumbaut & Walter Ewing (Spring 2007). "The Myth of Immigrant Criminality and the Paradox of Assimilation: Incarceration Rates among Native and Foreign-Born Men", The Immigration Policy Center.
Bryan Balin (2008). State Immigration Legislation and Immigrant Flows: An Analysis The Johns Hopkins University
Douglas S. Massey (September 2005). "Beyond the Border Buildup: Towards a New Approach to Mexico-U.S. Migration", Immigration Policy Center, the American Immigration Law Foundation
IPC Special Report (November 2005). "Economic Growth & Immigration: Bridging the Demographic Divide", Immigration Policy Center, the American Immigration Law Foundation
American Immigration Council (April 2014). "Immigrant Women in the United States: A Demographic Portrait"
Jill Esbenshade (Summer 2007). "Division and Dislocation: Regulating Immigration through Local Housing Ordinances". American Immigration Council
Jeffrey S. Passel & Roberto Suro (September 2005). "Rise, Peak and Decline: Trends in U.S. Immigration". Pew Hispanic Center
Jeffrey S. Passel (March 2005). "Estimates of the Size and Characteristics of the Undocumented Population". Pew Hispanic Center
Jeffrey S. Passel (March 2007). "Growing Share of Immigrants Choosing Naturalization". Pew Hispanic Center
UNCTAD's Classification of Non-Tariff Measures (2012) report
Borders
Export and import control
International relations
Border crossings
International law
Travel
Visas | Internal border control | [
"Physics"
] | 6,051 | [
"Travel",
"Physical systems",
"Transport",
"Space",
"Spacetime",
"Borders"
] |
70,574,453 | https://en.wikipedia.org/wiki/Thermosediminibacteraceae | Thermosediminibacteraceae is a family of Gram positive bacteria in the class Clostridia.
Taxonomy
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).
Genus Caldanaerovirga Wagner et al. 2009
C. acetigignens Wagner et al. 2009
Genus Fervidicola Ogg & Patel 2009
F. ferrireducens Ogg & Patel 2009
Genus Thermosediminibacter Lee et al. 2006
T. litoriperuensis Lee et al. 2006
T. oceani Lee et al. 2006 (type sp.)
Genus Thermovenabulum Zavarzina et al. 2002
T. ferriorganovorum Zavarzina et al. 2002 (type sp.)
T. gondwanense Ogg, Greene & Patel 2010
Genus Thermovorax Makinen, Kaksonen & Puhakka 2012
T. subterraneus Makinen, Kaksonen & Puhakka 2012
Phylogeny
See also
List of bacteria genera
List of bacterial orders
References
Bacteria families
Clostridia
Thermophiles
Anaerobes | Thermosediminibacteraceae | [
"Biology"
] | 258 | [
"Bacteria",
"Anaerobes"
] |
70,574,470 | https://en.wikipedia.org/wiki/Tepidanaerobacteraceae | Tepidanaerobacteraceae is a family of Gram positive bacteria in the class Clostridia.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI).
See also
List of Bacteria genera
List of bacterial orders
References
Bacteria families
Clostridia
Thermophiles
Anaerobes | Tepidanaerobacteraceae | [
"Biology"
] | 88 | [
"Bacteria",
"Anaerobes"
] |
70,575,023 | https://en.wikipedia.org/wiki/Libs%20of%20TikTok | Libs of TikTok is a handle for various far-right and anti-LGBT social-media accounts operated by Chaya Raichik ( ), a former real estate agent. Raichik uses the accounts to repost content created by left-wing and LGBT people on TikTok, and on other social-media platforms, often with hostile, mocking, or derogatory commentary. The accounts promote hate speech and transphobia, and spread false claims, especially relating to medical care of transgender children. The Twitter account, also known by the handle @LibsofTikTok, has over 3.5 million followers as of September 2024 and has become influential among American conservatives and the political right. Libs of TikTok's social-media accounts have received several temporary suspensions and a permanent suspension from TikTok.
Some Libs of TikTok posts have resulted in harassment against teachers, medical providers, children's hospitals, libraries, LGBT venues, and educational facilities, several of which received bomb threats after being featured on a post. Libs of TikTok posts regularly label LGBT people, as well as those who provide mental-health services to LGBT youth and LGBT sex education to students, as "groomers". Its followers "routinely attack individuals whose content is shared", and several dozen incidents of online or real-life threats and harassment against a range of targets, including 21 bomb threats, have been linked to Libs of TikTok's tweets, especially those where Raichik singles out specific events, locations or people.
Raichik created the Twitter account in November 2020, and, after adopting a series of different handles, she changed its name to @LibsofTikTok in April 2021. Later that year, the account began receiving media attention, including from conservative commentators and news outlets. Raichik remained anonymous until her identity was revealed in April 2022 by software developer Travis Brown and The Washington Post journalist Taylor Lorenz. In August 2022, Libs of TikTok received substantial media attention after falsely claiming that gender-affirming hysterectomies were being provided to minors at the Boston Children's Hospital and at the Children's National Hospital. This resulted in harassment campaigns, including bomb threats, against both hospitals. Libs of TikTok's videos have also been promoted by Russian and European disinformation networks, particularly a Kremlin-backed anti-LGBTQ disinformation campaign.
Account history
Inception and original content (November 2020 – June 2021)
In November 2020, Raichik created a Twitter account with the handle @shaya69830552, which she later changed to @shaya_ray. According to The Daily Dot, "in its early days, [the account] primarily existed as a reply account that routinely showed up in the comments of prominent conservatives on Twitter." Under these prior handles, Raichik downplayed the severity of COVID-19, promoted the disproven conspiracy theory that the 2020 United States presidential election was stolen from Donald Trump through election fraud, and made posts showing that she was present at the 2021 United States Capitol attack. Raichik criticized the law enforcement officers at the Capitol. She tweeted that she did not enter the Capitol building like "a few crazy people" had and called the breach "mostly peaceful", and she later favorably compared the attack to a Black Lives Matter protest. As of early 2021, the account had less than 1,000 followers.
The account's handle was later changed to @cuomomustgo, focusing on demanding the resignation of then-governor of New York Andrew Cuomo following the sexual harassment allegations levied against him. Raichik also used the account to advocate for the recall of California governor Gavin Newsom. By March 2021, the handle had changed to @houseplantpotus, a parody account tweeting as a houseplant in the White House during the presidency of Joe Biden. On April 19, 2021, Raichik adopted the moniker @libsoftiktok, promising to "help you find your daily dose of cringe". In May and June 2021, before and during Pride Month, Libs of TikTok started posting anti-LGBT commentary, including her first tweet promoting the LGBT grooming conspiracy theory. The account's early reposts also included reposts of videos by progressives about Anthony Fauci and vaccinations that it deemed cringeworthy. Slate linked Libs of TikTok's early success to "shamelessly tagging alt-right and far-right heavy hitters on Twitter, a strategy she continues to use to this day".
Media attention (August 2021 – April 2022)
By August 2021, Libs of TikTok had amassed around 65,000 followers. In August 2021, podcaster Joe Rogan began promoting @LibsofTikTok on The Joe Rogan Experience, leading to a large increase in followers. That same month, lawyer and Republican Party operative Grant Lally filed a trademark for Libs of TikTok as a "news reporter service". The account has been promoted by Donald Trump Jr., journalist Glenn Greenwald and political commentators Tucker Carlson, Jesse Watters and Laura Ingraham; has been featured in the New York Post, The Federalist, The Post Millennial, Fox News and in other right-wing news outlets; and its posts have been retweeted by Meghan McCain.
Prior to being revealed as the account creator, Raichik was interviewed anonymously on several occasions, during which she boasted that posts from the account led to the firings of several teachers. Raichik encouraged followers to join local school boards in order to remove teachers who teach about gender and sexuality. Raichik told the New York Post that "I don't do this for money or fame" and "I'm not some politician or blue-check journalist."
Identity revelation (April 2022)
In April 2022, details began to surface about Libs of TikTok's identity. Raichik had registered the domain name LibsofTikTok.us earlier in October 2021; .us domains do not allow for anonymous registration, meaning Raichik's full name and other information was listed publicly on the WHOIS record for the domain. This enabled software developer Travis Brown to name Raichik as the account's creator in early April 2022.
On April 19, 2022, The Washington Post published an article by journalist Taylor Lorenz which further publicized Raichik's identity, noting that she worked in real estate in Brooklyn and that she was "proudly" Orthodox Jewish. These details were scraped from early iterations of the Libs of TikTok Twitter account. The online version of the article initially included a link to Raichik's real estate license, although it was later removed.
Lorenz's article was controversial, particularly among American conservatives, and she was criticized for her methods in reporting the piece, for revealing Raichik's identity at all, for antisemitism (having mentioned Raichik's claim regarding her faith), and for hypocrisy (having previously spoken out against online harassment). Some critics accused Lorenz of doxxing Raichik, though Lorenz countered that Raichik's information had already been publicly available. Lorenz and The Washington Post stood by the reporting. Cameron Barr, a senior managing editor at The Washington Post, wrote in a statement that the Post "did not publish or link to any details about [Raichik's] personal life", though Raichik noted that a home address was listed on the real-estate license the article originally linked to. Lorenz said that her critics are trying to "sow doubt and discredit journalism".
Raichik personally accused Lorenz of doxxing and of violating her right to free speech, though she vowed she would "never be silenced". The following month, Raichik tweeted that she had "received about a dozen death threats", including threats from people threatening to throw a pipe bomb into her house. Lorenz also reported that she faced personal backlash, noting that, in response to the article, her "whole family" had been doxxed, and that "trolls [then] moved on to doxxing and stalking any random friends I've tagged on Instagram".
The Libs of TikTok account gained 200,000 followers the day after The Washington Post'''s story was published.
Lorenz arranged an interview two years after The Washington Post article, during which Raichik argued against gender-affirming care and discussed whether Raichik counted herself as a public figure with regard to her outing.
Content
Libs of TikTok has been described as right-wing, conservative, far-right, extreme right-wing, and extremist. The Times of London described the account as a "Twitter provocateur". The account is generally devoted to reposting content from left-leaning social-media accounts that sparks outrage among its right-wing followers. The reposted videos are most often LGBT-related.
Drag-show-related content
Raichik contends that adults teaching children about LGBT identities is abusive and constitutes child grooming. She often uses Libs of TikTok to publicize LGBT events either involving or aimed at youth, and, on more than one occasion, some of these events have been targeted by right-wing extremists. Raichik has claimed that being gender non-conforming or being an ally of the LGBT community is a "mental illness", and deliberately misgendered transgender people.
In June 2022, Libs of TikTok had some of their tweets removed after they posted the locations of a drag-focused events in the United States, including at least one Drag Queen Story Hour that was geared toward preschool-aged children. That location, in San Lorenzo, California, was stormed by the Proud Boys, a far-right extremist group. Pride events in Dallas and Coeur d'Alene were also targeted by right-wing extremists after Libs of TikTok posted about them; at the Coeur d'Alene event, 31 Patriot Front members were arrested before getting to their destination. In June, a spokesperson for the Alameda County Sheriff's Office said investigators believe that the Proud Boys confrontation was caused by Libs of TikTok. In August, NPR reported that "no conclusive link between the posts and the extremist groups' activities" had been established.
The Proud Boys have also targeted or threatened to target other events Libs of TikTok has publicized, including a Woodland, California, bar's drag happy hour (which Raichik said was hosted by a "youth group" for "all ages"), a drag brunch planned to benefit a local LGBT resource center in Sanford, North Carolina, and a drag-queen story hour that was planned (and then cancelled) by a K-5 school in Columbus, Ohio.
In November, a South Dakota State University LGBTQ student group was the target of a bomb threat being investigated by the University Police Department, after Libs of TikTok posted alleged footage of that year's annual drag event, which was advertised as all-ages. The student group and the performer at the center of the event said Libs of TikTok's video spliced together scenes of that year's event with the previous year's event, which had been age-restricted.
In May 2023, it was reported that the shooter responsible for the Allen, Texas shooting had dedicated to Libs of TikTok a long screed he posted to social media denouncing Drag Queen Story Hour.
Gender-affirming-care-related content
Raichik opposes gender-affirming surgery on children, arguing that it is mass scale child abuse and that "[a]ny doctor performing these surgeries should have their license revoked. They belong in prison".
In August 2022, on Libs of TikTok social-media accounts, Raichik claimed that Boston Children's Hospital (BCH) and Children's National Hospital (CNH) were providing gender-affirming bottom surgeries to minors. With the BCH-related content, Raichik included a BCH video that featured one of the hospital's gynecologists explaining the procedure. USA Today, NPR, and PolitiFact concluded that BCH claim was false. The CNH content was an audio recording with two operators who stated that 16-year-old trans boys would be eligible for hysterectomies at the hospital. CNH denied the operators' statements and noted that "[n]one of the people who were secretly recorded by this activist group deliver care to our patients". Several conservative outlets—including The Daily Caller and The Post Millennial—republished one or both stories.
Both hospitals' websites featured mistaken information as to the eligibility for gender-affirming bottom surgeries: A public-facing file on BCH's website said that vaginoplasty patients must be "between 17 and 35 years of age at the time of surgery"; when asked about this document, the hospital explained that it had since been updated to reflect the protocol it said it had "always adhered to"—that, while consultations were available to 17 year olds, only those over 18 were eligible for the surgery. CNH's website had stated that hysterectomies were provided to patients "between the ages of 0–21". But a spokeswoman for the hospital stated: "We do not and have never performed gender-affirming hysterectomies for anyone under the age of 18."
After the Libs of TikTok posts, each hospital's employees were subject to harassment, and both BCH and CNH were subject to bomb threats, though it was unclear whether each of the threats were related to the harassment. NBC News described Libs of TikTok as "one of the primary drivers of the harassment campaign" against BCH. The threats of violence were widely denounced, and both state and federal authorities launched investigations into the threats. When contacted by The Washington Post, Raichik did not answer a question about whether she felt responsible for the threats against the hospitals, but said that "we 100% condemn any acts/threats of violence". In a later tweet, Raichik said that she would continue to call out hospitals, and, in the aftermath of the CNH tweets, after which Twitter temporarily suspended the Libs of TikTok account, Raichik said, "Getting suspended by Twitter has only made me realize my biggest mistake. I only called one hospital I should have called dozens because I promise you Children's National is not the only one. I promise to learn from my mistake and uncover more of what our Big Tech overlords don't want us to know. I will do better in the future."
Raichik subsequently posted stories about Akron Children's Hospital and Barbara Bush Children's Hospital providing non-surgical gender-affirming care, including puberty blockers, to minors. Raichik also posted about an adolescent clinic at Johns Hopkins All Children's Hospital, highlighting its practice of asking parents to step out of the room for a few minutes to give young patients a "safe space". In response to the social-media attention, which included threats, Akron Children's Hospital temporarily took down the gender-affirming care section of their website and information about its employees and the care they provide.
The account has targeted other hospitals that provide gender-affirming care, in some cases with false claims, including a children's hospital in Omaha, Nebraska, UPMC Children's Hospital of Pittsburgh, and Phoenix Children's Hospital, leading to phoned-in threats and harassment. After Libs of TikTok's targeting of specific hospitals, other pediatric facilities including Chicago's Lurie Children's Hospital have faced harassment and false claims about care they provide. In September 2022, in response to Libs of TikTok's posts, Lurie Children's Hospital increased its security and moved a transgender youth support group from in-person meetings to online meetings.
Teaching-related content
Teachers supporting LGBT students have been noted as one of the "most frequent" targets of the Libs of TikTok account. Several of the teachers targeted have reported harassment and death threats. According to a report by the left-leaning media watchdog group Media Matters for America, between January and April 2022, the account named or tagged around 222 educational institutions and teachers. According to Euronews, "some of the people targeted by [Libs of TikTok] have received hundreds or even thousands of hate comments."
On November 16, 2021, an assistant professor at Old Dominion University was placed on administrative leave after an interview in which the professor argued that pedophilia should be destigmatized was posted on the Libs of TikTok account and went viral. On November 24, the professor resigned from their position.
A teacher in California was placed on administrative leave after a video she posted joking about asking her students to pledge allegiance to a Pride flag was reposted by Libs of TikTok on August 27, 2021. After conservative and far-right accounts attacked her on social media, she deleted all of her social media accounts.
In April 2022, Raichik reposted a video supporting LGBT students by an 8th grade English teacher in Owasso, Oklahoma; in the video, the teacher stated, "If your parents don't accept you for who you are, fuck them. I'm your parents now. I'm proud of you. Drink some water. I love you". After parents complained about the video, the teacher resigned, later telling the Washington Post he had received death threats from Libs of TikTok's followers. Oklahoma Republican Senate candidate Jackson Lahmeyer accused the teacher of being a "predator". Libs of TikTok later made a post claiming, without evidence, that the teacher was fired "after complaints of grooming". Some parents defended the teacher, saying that he provided a "safe haven" for LGBT students.
In October 2022, a Huntsville, Alabama, animal shelter faced backlash, including death threats and negative reviews on Google, after Libs of TikTok reposted a video from the shelter showing a middle school teacher reading in drag. Libs of TikTok alleged the teacher made lewd sexual innuendos and jokes to a room of children. As a result, the teacher was put on indefinite paid administrative leave by Huntsville City Schools for investigation. The teacher defended his comments, comparing them to innuendos in kids' movies. The animal shelter supported the teacher and the event, emphasizing their commitment to inclusivity and kindness. The teacher also received death threats.
Educational facilities and bomb threats
Multiple educational facilities and institutions that were featured in posts by Libs of TikTok have reported receiving bomb threats afterwards. When contacted by Vice, Raichik stated that "the threats had nothing to do with her or her followers." According to an October 2023 report by Vice, out of 42 establishments featured in Libs of TikTok posts that Vice contacted, 11 schools and school districts had reported receiving bomb threats. Although a direct connection between Libs of TikTok's posts and the threats were not made, some have found the nature of these threats to be unusual.
In August 2023, an Ellen Ochoa Elementary School (part of Union Public Schools in Tulsa, Oklahoma) librarian's video was edited and shared by Libs of TikTok and reposted by Oklahoma State Superintendent Ryan Walters. After the video was shared, both Ellen Ochoa Elementary School and the librarian's home received multiple bomb threats. Bombing threats were accompanied by letters to media threatening to bomb "every school in the union district", unless the schools stopped "pushing this woke ideology".
In August 2023, Libs of TikTok accused a California elementary school of being "racist against white people". The next day, a bomb threat was emailed to the school and it was evacuated; local police described the email as having "racial undertones". Around the same time, a library in Davis, California, became the target of bomb threats after Libs of TikTok tweeted about an event in the establishment which resulted in a group of speakers being asked to leave over speech that was hostile towards trans athletes. According to local police, the threats were laden with hate speech of some kind.
In September 2023, a school in Illinois received three bomb threats in four days after Libs of TikTok posted a picture of one of its classrooms where a Pride flag was hanging. The school evacuated students twice, on consecutive days, after the threats were received.
In February 2024, NBC News reported 33 instances of violent threats being made against individuals or organizations that Libs of TikTok had previously posted about since November 2020, 20 of which were bomb threats. The report further commented saying, "the timing suggests that Libs of TikTok posts have been used to pick targets." In at least three instances, those bomb threats led to criminal charges against at least 9 individuals.
Other content and hoaxes
In reference to a preschool that held a gay pride march, the account stated, "stop sending your kids to indoctrination camps". It has encouraged followers to contact schools that allowed transgender students to use bathrooms corresponding to their gender identity. Libs of TikTok also aims to "spread the horrors of what doctors are doing to young, confused individuals".
In since-deleted tweets, the account specifically accused Chasten Buttigieg and The Trevor Project organization of grooming. The account argued in another since-deleted tweet that any teacher who comes out as gay to their students should be fired.
Libs of TikTok has been criticized for spreading hoaxes, including the litter boxes in schools hoax about bathroom accommodations for students that identified as cats, and for spreading false claims such as that students in a second-grade class in Austin, Texas were being taught about furries, and that U.S. Representative Katie Porter had argued that pedophilia is not a crime after Porter lamented that LGBT people were being slandered as pedophiles and groomers on social media. The account has also posted, or been accused of posting, edited footage of drag events, in one case resulting in bomb threats against the audience and the performer in North Dakota, and in a separate incident resulting in death threats against a drag performer who eventually resigned from a teaching position in Alabama.
Libs of TikTok has denied the existence of systemic racism, but argued that racism against white people was "flourishing" in the United States. Reporting by Slate stated that "Raichik's feed is colored by an intense hostility to liberals generally, but she holds an especially pronounced animosity toward LGBTQ people, city dwellers, and Black people who have been killed at the hands of police", noting that the account has referred to George Floyd as a criminal, and mocked the killing of Ma'Khia Bryant.
The most popular video posted on Libs of TikTok, with 5.7 million views, was taken by a female student at Arizona State University. The video shows her and her friend repeatedly asking a white male student to leave a multicultural center due to a "Police Lives Matter" sticker on his laptop. After the video went viral, ASU investigated and then reprimanded the two female students.
Colorado Springs nightclub shooting
On November 20, 2022, Libs of TikTok received renewed media attention following the Colorado Springs nightclub shooting, a mass killing that took place at an LGBTQ venue in which five people were killed and dozens more were injured. Club Q, the venue targeted by the shooter, frequently hosts drag events, including those advertised to an all-ages audience. The Independent noted that Libs of TikTok often attracts negative attention to such events with her social media accounts and that harassment and threats are often sent by her followers against patrons and performers following her postings. Hours after the shooting, Raichik used her Twitter account to target a "drag organization" in the same state where the massacre took place, underlining the names of two Colorado state legislators, one of whom was trans, for supporting it. The Advocate criticized the post, saying that: "In the hours after news of the Club Q shooting spread, Raichik, for example, doubled down on her anti-LGBTQ+ messaging by posting about other drag-inclusive events in the state." They drew attention to an interview previously published on their website with Juliette Kayyem, a former assistant secretary at the Department of Homeland Security, in which she stated that social media accounts such as Libs of TikTok practice stochastic terrorism by provoking extremist outrage against marginalized groups, but using "vague language that allows the agitator to deny responsibility for the act".
Account suspensions
Twitter
Twitter has temporarily suspended the Libs of TikTok account five times, including for promoting "violence, threats or harassment against others" based on minority status and for "hateful conduct". At least two of the suspensions stemmed from Raichik misgendering persons in tweets.
On September 25, 2022, Libs of TikTok received a one-week suspension from Twitter and claimed that Twitter did not cite a reason for the suspension. However, The Babylon Bee CEO Seth Dillon said that Libs of TikTok was suspended for "hateful conduct" with "no specific tweets [being] flagged". In response to the suspension, Libs of TikTok hired a law firm that sent a letter threatening legal action against Twitter if they decide to permanently suspend Libs of TikTok. Libs of TikTok also created a legal defense fund and encouraged her supporters to donate to the fund. Libs of TikTok said that the suspension was "the result of a targeted harassment campaign from the Left to deplatform me", adding that "The truth is I haven't engaged in hateful conduct. I've just exposed the Left's depravity by reporting the facts. There's no rule against that, so they have to make up violations I've never committed".
LGBT advocates on Twitter have advocated for Twitter to permanently suspend Libs of TikTok, and several commentators noted that Twitter had not imposed an outright (permanent) ban on the account. According to NPR, "Libs of TikTok appears to have evaded outright bans by coming right up to the edge of the platforms' rules but not breaking them", adding that the account "does not explicitly encourage followers to threaten anyone, and typically uses its target's own words, sometimes stripped of context, to imply wrongdoing." According to Joan Donovan, research director of the Shorenstein Center on Media, Politics and Public Policy, Raichik dodges bans by deleting problematic tweets before the platform takes action, a tactic Donovan said is common for digital actors spreading disinformation.
From roughly August to October 2022, Libs of TikTok was the subject of significant internal conversation at Twitter, with some employees arguing that the account should be permanently banned due to its potential for inciting violence. After Elon Musk acquired Twitter and became its CEO in October 2022, the site's moderation activity was reduced significantly. On December 9, journalist Bari Weiss claimed that Twitter had limited Libs of TikTok's reach via shadow banning, a claim that was rejected by Twitter's former head of product, Kayvon Beykpour, who replied with "You are characterizing any de-amplification as equating to shadow banning which is either a lazy interpretation or deliberately misleading". Conversely, Evan Urquhart of Slate argued that Weiss' own publishing revealed that Libs of TikTok was receiving preferential treatment, with moderators directed not to take any action against the account and to instead elevate issues to higher management. Urquhart further argued that Weiss' portrayal of Libs of TikTok dangerously conflated conservative opinions with stochastic terrorism and extremism.
Bluesky
Libs of TikTok joined the social media platform Bluesky in late November among millions of users who joined the platform following the results of the 2024 US Presidential Election with many users leaving Twitter. The account was reportedly suspended after 9 days on the platform on December 2, 2024. In a statement to The Advocate, a spokesperson for media watchdog GLAAD praised the account's removal: "Social media platforms have hate speech policies for a reason — to maintain a safe environment for all users, and advertisers, and especially to protect historically marginalized groups, such as LGBTQ people, who are disproportionately targeted with hate and harassment."
Other platforms
Libs of TikTok had an account on TikTok itself, but it was suspended for violating TikTok's community guidelines in March 2022. The Libs of TikTok Instagram account was suspended for a few hours two months later, which a Meta spokesperson said was from an automated system responding to "multiple copyright complaints". In September of that year, the Libs of TikTok Facebook account was permanently suspended for violating the platform's community guidelines. Facebook said it was suspended in error and the account was reinstated after less than a day, an action that the LGBT organization GLAAD criticized. Activists campaigned for e-commerce platform Shopify to drop Libs of TikTok's store, claiming that it violated the platform's acceptable use policy which bans hateful content and goods and services that lead to harassment and threats. In a statement, Shopify defended Libs of TikTok, saying that "We host businesses of all stripes and sizes, with various worldviews".
Impact
Political impact
Florida governor Ron DeSantis's press secretary Christina Pushaw credited the account for "opening her eyes" on the current state of education around sexuality- and LGBT-related topics. Pushaw interacted with the Libs of TikTok account more than 100 times between July 2021 and May 2022. Fox News host Tucker Carlson has credited Libs of TikTok, and Pushaw's championing of it, as partly responsible for Florida's passage of the 2022 Parental Rights in Education bill (commonly called the "Don't Say Gay bill"), which prohibits instruction on sexuality and gender identity in age-inappropriate ways from kindergarten to third grade in public schools.
Libs of TikTok was one of the top-ten most influential Twitter accounts in promoting use of the pejorative term groomer after the passage of Florida's Parental Rights in Education bill, according to a report by the Center for Countering Digital Hate and the Human Rights Campaign. Raichik uses the term as a pejorative for LGBT people, supporters of LGBT youth, and those who teach about sexuality.
On March 5, 2024, Libs of TikTok account on Twitter posted a video linking an LGBT+ center in Philadelphia to the promotion of a "BDSM, kink and fetish" event, and accused Senators Bob Casey and John Fetterman of sending the center earmarked funds. On the same day, Fetterman's and Casey's offices requested the Congress to cut the earmarks worth US$1 million they initially proposed from the national spending bill that was about to pass. On March 6, however, Fetterman denied he himself took his office's decision, and implied his staffers were pushed by Libs of TikTok's accusations. In a later statement, Fetterman said his staff felt it was up to his office to "pull it or watch it get stripped out, attacked by Republicans, and ultimately killed" adding he would push for LGBT funds in 2025.
Harassment and threats
According to a report by Advance Democracy Inc., tweets by Libs of TikTok result in a spike in mentions of specific hospitals and doctors across Twitter. In many of the mentions, doctors are referred to as "child molesters", "pedos", "groomers", and "butchers".
Drag queens and drag events organizers said that they received harassment and threats after tweets from Libs of TikTok about them and their work. In 2021, Libs of TikTok encouraged its followers to call child protective services (CPS) on a transgender couple who were shown in the Facebook Watch documentary series 9 Months with Courteney Cox attempting to breastfeed their newborn baby.
In July 2022, OutLoud North Bay, a centre for LGBT youth in Ontario, received hate messages and death threats after Libs of TikTok posted tweets in response to the centre announcing a drag show for all ages. Also in July, Libs of TikTok made a tweet criticizing the Conservative Jewish camping network, Camp Ramah in Northern California, for "housing kids according to their gender identity rather than birth sex".
On August 10, 2022, Libs of TikTok reposted a video of a therapist who works with sex offenders who have been jailed. In the video, the therapist says their pronouns and advises people to use the term "minor-attracted persons" (MAPs) instead of "pedophiles", arguing that the latter term has "moved from being a diagnostic label to being a judgmental, hurtful insult that we hurl at people in order to harm them or slander them". They also argue that pedophiles do not choose their attraction to children and should not be solely defined by that one aspect of themselves. Libs of TikTok only posted the first two minutes of the video, which made it sound like the therapist was advocating for acceptance of pedophilia and for people to be nicer to child sex abusers. In the full version of the video, the therapist condemns child sex abuse crimes. Libs of TikTok's reposted video has been promoted by Russian and European disinformation networks, such as Tsargrad TV.
Michael O'Brien, a pediatrics resident at a hospital in South Carolina, said that he received threats after Libs of TikTok, on August 15, retweeted a tweet in which he had criticized the account. O'Brien reported some of the threats to his employer's public safety office: "I got three specific threats that came from within a 50-mile radius of where I live", adding that "The threats felt very tangible. I had to take action to protect my partner and warn my family."
In September 2022, Libs of TikTok claimed that workshops for transgender youth and their families run by the American healthcare company Kaiser Permanente were being held "without parental consent" despite the workshops being designed for both children and parents. Also in September 2022, a tea shop in Salt Lake City reported receiving "an endless barrage of harassment" after Libs of TikTok's Instagram account reposted a video featuring a young girl dancing with a drag queen inside the tea shop.
On September 23, 2022, a two-minute video of Dr. Katherine Gast (co-director at the University of Wisconsin-Madison's UW Health gender services program) describing gender-affirming surgeries was reposted by Libs of TikTok with the caption: "Gast happily describes some of the "gender affirming" surgeries she offers to adolescents including vaginoplasties, phalloplasties, and double mastectomies." In an emailed response to NBC News, Libs of TikTok stood by her characterization of doctors who work in transgender healthcare. Although Gast does not perform genital surgery on minors, she does perform mastectomies (also known as "top surgery") in some cases for older teenagers after evaluations by mental health care professionals and doctors, and with parental consent. The original tweet by Libs of TikTok received almost half a million views, one of eight in a thread about Gast and her patients. Senator Ted Cruz tweeted: "She does this to children. Sterilizes & mutilates them. Before they are old enough to consent." Gast and her family were doxxed and her clinic has received "harassing phone calls".
In April 2024, over forty Planet Fitness establishments throughout the United States received bomb threats after Libs of TikTok posted that a customer was banned for photographing a transgender woman while she used the women's room.
After analyzing Libs of TikTok's online activity in April 2022 through November 2022, a counter-extremism research group named "Task Force Butler Institute" estimated Raichik singled out a specific event, location or person over 280 times, resulting in 66 incidents of harassment or threats against her targets.
Reception
Response to account content
The account has been described as promoting harassment against and criticizing teachers, medical providers, and children's hospitals. It has been called a hate-speech account. It has also been described as spreading misinformation and/or disinformation by reposting videos clips of LGBT people, teachers, schools and other institutions out of context and with incendiary framing. While fans and supporters of Libs of TikTok say the account simply reposts content showcasing "sex and gender ideology" that was already publicly available, "the account's followers are rabidly anti-LGBTQ+ and routinely attack individuals whose content is shared."
Raichik has described Libs of TikTok's reposting of videos as "exposés" of "the crazies". She has also described criticism of her online activity as efforts to "cancel and silence" and has said that she receives death threats.
Positive
Tucker Carlson, then the host of Tucker Carlson Tonight, praised Libs of TikTok, saying that "no news organization in America has done more to reveal the reality in American schools than Libs of TikTok" and called the videos reposted by the account "idiotic and disgusting". Donald Trump Jr. argued that "the question Libs of TikTok often raises And the Left wants to ignore Is do parents have a right to know what their children are being taught in their public school, or not?" Ben Shapiro defended Libs of TikTok from criticism, calling it "a Twitter account that literally just posts Leftists owning themselves." Seth Dillon of The Babylon Bee called Libs of TikTok's work "heroic" and "high-risk". Christina Pushaw has described herself as "a strong supporter of [Libs of TikTok']s mission."
Negative
Gillian Branstetter, a media strategist for the American Civil Liberties Union, argued that Libs of TikTok "is finding new characters for right-wing propaganda" and that "it's relying on the endless stream of content from TikTok and the Internet to cast any individual trans person as a new villain in their story." Ari Drennen, the LGBTQ program director for the left-leaning media watchdog group Media Matters for America, argued that "Libs of TikTok is basically acting as a wire service for the broader right-wing media ecosystem", adding that the account has "been shaping public policy in a real way, and affecting teachers' ability to feel safe in their classrooms". According to Drennen, she received more than 500 hateful comments about her sexuality and appearance after criticizing Libs of TikTok. Kylie Cheung of Jezebel argued that "Deplatforming hateful accounts like LibsOfTikTok whose online attacks can clearly, quickly escalate into real-life threats is an important step. But it's clear we're in the midst of a terrifying, broader anti-LGBTQ moment right now that's being fueled by pretty much every right-wing media outlet as well as top Republicans." Reina Sultan of Them argued that "social media platforms are not doing enough, not only to limit Libs of TikTok's ability to spread hate, but also to protect LGBTQ+ people in general." Elad Nehorai of The Forward argued that Libs of TikTok is "fueling a pogrom against trans youth", comparing accusations of grooming to antisemitic blood libel. LGBT organization GLAAD said in a statement that "Libs of TikTok is synonymous with maliciously targeting LGBTQ organizations, people, and allies by posting lies, misinformation, and blatant hate."
Joan Donovan, research director at Harvard's Shorenstein Center on Media, Politics and Public Policy, argued that "we've reached this phase in social media where people know what to do when an account like Libs of TikTok calls out another account or a person or institution", calling the response to these posts "networked incitement" that can create "a snowball effect, where you see people getting more emboldened to participate". Donovan also argued that "the precipitating comments may not be that incendiary, but if that creates a pattern of attack that is recognizable, which it is with an account like Libs of TikTok, then these companies are well within their jurisdiction to warn and then ban the account." Donovan has drawn parallels between Twitter's handling of Libs of TikTok and Twitter's failure to stop QAnon, the Stop the Steal movement, and the January 6 Capitol attack, which Twitter only started cracking down on after several acts of violence were linked to these movements. She also drew parallels between right-wing media amplifying Libs of TikTok and the online campaign that resulted in the January 6 Capitol attack. Donovan noted that "We're seeing more people feeling — as they did during the insurrection — that storming a hospital might be their only option to defend themselves and their values". Harvard Law School clinical instructor and transgender activist Alejandra Caraballo argued that Twitter has not banned Libs of TikTok for its content because "they don't want to rock the boat politically while the [Elon Musk purchase] is ongoing." Meredithe McNamara, assistant professor of pediatrics at Yale University, argued that "allowing this hate speech to fester on the internet and fuel direct threats is going to create long standing harms that are difficult to recover from".
Response to identity reveal
Bonnie Kristian of The Week argued "the person behind Libs of TikTok doesn't matter much... because conspiracism is communal now", adding that "Lorenz's exposé largely missed the point." Kat Rosenfield of UnHerd called The Washington Post article "an unmasking worthy of a demented superhero story", adding that "it's hard to know what Libs of TikTok's greater sin is: being wrong, or being popular." Dan McLaughlin of National Review argued that identity reveals like that of Libs of TikTok have "become standard practice for major media reporters who do stories on people on the right who can be framed as 'extremists.'"
Kara Alaimo, a Hofstra University professor and former Obama administration staffer writing for NBC News, dismissed criticism regarding identifying the individual running the account, arguing that "the people in need of protection here are those who are being targeted with hate simply because of their identities not the people who are hurling the abuse, like Raichik."
Writing about the revealing of Raichik's identity, Kaitlyn Tiffany of The Atlantic argued that "where the term [doxxing] once defined a category, it now expresses an emotion. Whoever feels doxxed will claim to have been doxxed."
Commentator and conspiracy theorist Jack Posobiec tweeted: "This isn't journalism. This is doxxing and smearing of Libs of TikTok by the billionaire-controlled Bezos Post".
Some Jewish critics, including watchdog organization StopAntisemitism.org and Jewcy magazine editor Isaac de Castro, argued that Lorenz's mention of Raichik's Orthodox Judaism was unnecessary and promoted antisemitism. Andrew Silow-Carroll, editor in chief of The Jewish Week, defended the inclusion of Raichik's religious beliefs in a blog for The Times of Israel, arguing that it "shed light on the growing connection between faith and right-wing politics".
In April 2022, another Orthodox Jew also named Chaya Raichik, a stay-at-home mom who grew up in Los Angeles, received hundreds of negative messages from people who mistook her for the person behind Libs of TikTok. Also in April, YouTuber Tim Pool and The Daily Wire CEO Jeremy Boreing purchased a billboard in Times Square to accuse Lorenz of doxxing Libs of TikTok. In response, Lorenz called the billboard "so idiotic it's hilarious."
Classifications of extremism
In March 2024, the Southern Poverty Law Center (SPLC) added Chaya Raichik to their hate watchlist as an anti-LGBTQ extremist. The entry describes Raichik as having engaged in an "anti-LGBTQ+ disinformation campaign" that "mobilizes right-wing extremist groups in violent attacks against LGBTQ+ people, spaces and events, as well as against doctors, hospitals, librarians, libraries, teachers and schools."
Other media involvement by Raichik
Television appearance
Raichik made her first-ever in-person televised appearance on the December 27, 2022, episode of Tucker Carlson Today. In the episode, she stated, "The LGBTQ community has become this cult, and it's so captivating, and it pulls people in so strongly... They're just evil. They're bad people. They're just evil people, and they want to groom kids. They're recruiting." Following her appearance, some news outlets have linked her to a person who may have trespassed on federal property during the January 6 United States Capitol attack.
Children's book
In 2023, Raichik announced her children's picture book No More Secrets: The Candy Cavern'', whose publisher is Brave Books. Promoted as "a modern twist to the familiar Grimm's-style fairy tale", the book is about a lamb named Rose who becomes suspicious when her second-grade teacher focuses more on candy than education. It reflects the LGBT grooming conspiracy theory; Raichik intended the book for helping children and their parents identify "predatory" behavior. Brave Books' storytime event which was to star Raichik and promote the book was canceled due to threats they viewed as dangerous.
Political appointments
In January 2024, Raichik was appointed as an adviser to the Oklahoma State Library Committee, despite not being an Oklahoma resident, a librarian, or an educator. The committee is tasked with reviewing material reported to them and advising schools on age appropriate media.
See also
LGBT rights in the United States
Transphobia in the United States
2020s anti-LGBTQ movement in the United States
Notes
References
External links
2020s anti-LGBTQ movement in the United States
Alt-right Jews
American conspiracy theorists
Anti-drag sentiment
Attacks on hospitals in the United States
Conservative media in the United States
Conspiracist media
Facebook criticisms and controversies
Far-right politics and Judaism
Harassment and bullying
Instagram accounts
Internet-based activism
Jewish American activists
Judaism-related controversies
Jewish women activists
LGBTQ and Orthodox Judaism
LGBTQ youth
LGBTQ-related controversies in the United States
People associated with the January 6 United States Capitol attack
Political extremism in the United States
Social media accounts
Terrorism in the United States
TikTok
Transphobia in the United States
Twitter controversies
Twitter accounts
Online obscenity controversies | Libs of TikTok | [
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70,576,296 | https://en.wikipedia.org/wiki/Women%20in%20Scientific%20and%20Engineering%20Professions | Women in Scientific and Engineering Professions is a 1984 book co-edited by American authors Violet B. Haas and Carolyn C. Perrucci. It was published through University of Michigan Press. The book was reviewed in several academic journals.
References
1984 non-fiction books
Women in science and technology
University of Michigan Press books
Women and employment | Women in Scientific and Engineering Professions | [
"Technology"
] | 67 | [
"Women in science and technology"
] |
70,576,470 | https://en.wikipedia.org/wiki/Colored%20Coins | Colored Coins is an open-source protocol that allows users to represent and manipulate immutable digital resources on top of Bitcoin transactions. They are a class of methods for representing and maintaining real-world assets on the Bitcoin blockchain, which may be used to establish asset ownership. Colored coins are bitcoins with a mark on them that specifies what they may be used for. Colored coins have also been considered a precursor to NFTs.
Although bitcoins are fungible on the protocol level, they can be marked to be distinguished from other bitcoins. These marked coins have specific features that correspond to physical assets like vehicles and stocks, and owners may use them to establish their ownership of physical assets. Colored coins aim to lower transaction costs and complexity so that an asset's owner may transfer ownership as quickly as a Bitcoin transaction.
Colored coins are commonly referred to as meta coins because this imaginative coloring is the addition of metadata. This enables a portion of a digital representation of a physical item to be encoded into a Bitcoin address. The value of the colored coins is independent of the current prices of the bitcoin; instead, it is determined by the value of the underlying actual asset/service and the issuer's desire and capacity to redeem the colored coins in return for the equivalent actual asset or service.
History
Colored coins arose due to the necessity to generate new tokens and move assets on the Bitcoin network. These tokens can be used to represent any asset in the world, including equities, commodities, real estate, fiat currency, and even other cryptocurrencies.
Yoni Assia, the CEO of eToro, was the first to suggest Colored coins in an article published on March 27, 2012. In the article titled bitcoin 2.X (aka Colored bitcoin), Assia claimed that the initial specifications that bitcoins transmitted using the "Genesis Transaction" protocol are recognizable, distinctive, and trackable on the ledger. The idea was growing, and on forums such as Bitcointalk, the concept of colored coins started to take form and gain traction. This culminated in Meni Rosenfeld releasing a whitepaper detailing the colored currencies on December 4, 2012.
The next year, in 2013, Assia collaborated with Buterin and five others, Lior Hakim, and Meni Rosenfeld, Amos Meiri, Alex Mizrahi and Rotem Lev to write Color Coins — BitcoinX, which explored the potential possibilities of colored coins.
In 2013, the New Scientist magazine first acknowledged Colored Coins where Meiri describes for the first time the actual issuance of a share or a gold bar on the blockchain. In 2014, Colu was the first company to raise venture capital money to develop the Colored Coins protocol.
Development
Colored coins originated as an afterthought by Bitcoin miners. The blockchain's data space had been utilized to encode numerous metadata values. This unexpected data caused processing issues, causing the network to slow down. The Bitcoin team fixed the problem by including a 40-byte area for storing data as a transaction, as well as an encrypted ledger of transactions and information about the coin's genesis.
While bitcoin was developed to be a cryptocurrency, its scripting language makes it possible to associate metadata with individual transactions. By precisely tracing the origin of a particular bitcoin, it is possible to distinguish a group of bitcoins from the others, a process known as bitcoin coloring (a term that served as a basis to the name of the Colored Coins protocol).
Through the oversight of an issuing agent or a public agreement, special properties can be associated with colored bitcoins, giving them value beyond the currency's value. One way of looking at this is from the abstraction that there are two distinct layers on top of bitcoin: the lower layer referring to the transaction network based on cryptographic technology and an upper layer that constitutes a distribution network of values encapsulated in the design of colored coins.
Due to the fact that colored coins are implemented on top of the Bitcoin infrastructure, allow atomic transactions (exchanged for each other in a single transaction) and can be transferred without the involvement of a third party, they enable the decentralized exchange of items that would not be possible through traditional means.
To create colored coins, "colored" addresses must be created and stored in "colored" wallets controlled by color-aware clients such as Coinprism, Coloredcoins, through Colu, or CoinSpark. The "coloring" process is an abstract idea that indicates an asset description, some general instructions symbol, and a unique hash associated with the Bitcoin addresses.
In 2013, Flavien Charlon, the CEO of Coinprism, developed a Colored Coin Protocol that permitted the generation of colored currencies by employing specified settings in transaction inputs and outputs. This was Bitcoin's first working Colored Coin Protocol. This protocol, also known as the Open Assets Protocol, is open source and may be integrated into existing systems by anyone.
On July 3, 2014, ChromaWay developed the Enhanced Padded-Order-Based Coloring protocol (EPOBC), which simplified the process of manufacturing colored coins for developers, and was one of the first to employ Bitcoin Script's new OP RETURN function.
In January 2014, Colu created the ColoredCoins platforms and Colored Coins protocol allowing users to build digital assets on top of the Bitcoin blockchain using the Bitcoin 2.0 protocol. In 2016, Colu announced integration to Lightning Network expanding its Bitcoin L2 capabilities.
Layers of Colored Coins
Colored coin functions by adding a 4th layer to the Bitcoin blockchain.
1st Layer: Network
2nd Layer: Consensus
3rd Layer: Transaction
4th Layer: Watermark (color)
Before ERC token standards were created, the concept of using tokens to represent and monitor real-world items existed. Colored coins were the original notion for representing assets on the blockchain. They are not widely used because the transaction structure required to represent colored coins relies on unspent transaction outputs, which Ethereum-based blockchain systems do not support. The primary concept is to add an attribute (the color) to native transactions that specify the asset it symbolizes. For example, for the Bitcoin blockchain, each Satoshi (the lowest potential value of Bitcoin) might represent a separate item. This notion is mostly used to monitor ownership of tokens and, by extension, assets. There is promise in using colored coins as an effective way of tracing in production situations since the transactions can be merged or divided into new transactions and the color can be readily altered after each transaction. Finally, current tools, like as blockchain explorers, make it simple to view and analyze transactions.
The nature of colored coins makes them the first non-fungible tokens to be created on the Bitcoin blockchain, albeit with limited features. Colored coins are transferrable in what is known as atomic transactions. Atomic transactions are transactions that permit the direct peer-to-peer exchange of one token for another in a single transaction. In this way, colored coins allow traditional assets to be decentralized.
Transactions
Colored coin uses an open-source, decentralized peer-to-peer transaction protocol built on top of WEB 2.0. Despite being created to be a protocol for monetary transactions, one of the Bitcoin's advantages is a secure transaction protocol not controlled by a central authority. This is possible through the use of Blockchain, which maintains track of all Bitcoin transactions worldwide.
A transaction consists of:
A set of inputs such that each input has (a) a Transaction Hash and Output Index of a previous transaction carried out on that bitcoin and (b) a digital signature that serves as cryptographic proof that that input address authorizes the transaction.
An output set such that each output has (a) the bitcoin value to be transferred to that output and (b) a script that maps a single address to that output.
Staining and transferring
The manipulation of colored coins can be performed through several algorithms, which create a set of rules to be applied to the inputs and outputs of Bitcoin transactions:
At a given moment, a digital resource is associated with the output of a Bitcoin transaction, called Genesis Transactions. The output of this transaction (currency) belongs to the initial owner recorded in the system (in a case of a jewelry store associating its jewelry with digital resources, the newly colored coins will belong to the store).
When the resource is transferred or sold, the currency that belongs to the previous owner is consumed, while a new colored currency is created at the outgoing address of the transfer transaction.
When it is necessary to identify the owner of a coin, it is enough to evaluate the transaction history of that coin from its genesis transaction to the last transaction with unconsumed output. The Bitcoin blockchain has tracking of the public keys associated with each address, such that the owner of the coin can prove ownership by sending a message with the private key associated with that address.
Among these algorithms, the best known of them is the EPOBC. The EPOBC algorithm colors the coins by inserting a mark in the nSequence field of the first input of the transaction. It is important to note that the nSequence field is always present in Bitcoin transactions, but it is not used, so it does not generate an overhead for the coloring process. Examples of companies driving the EPOBC are ChromaWallet, Cuber, LHV and Funderbeam.
Genesis transactions
To issue new colors, it is necessary to release coins of that color through genesis transactions. In general, there are two cases to consider about genesis transactions:
Non-reissuable colors: In this case, the transaction inputs are irrelevant to the algorithm, since once the transaction is executed, the coin issuer has no power over them. So all that matters is the genesis transaction itself.
Reissuable colors: In this scenario, the issuer must choose a secure address to be the “Issuing Address” and set transaction entry 0 to come from that address. In a second moment, the issuer will be able to issue new units of that color through genesis transactions with the same secure address. It is important to note that an address can only be associated with a single color. Once an address emits a reissuable color, it will no longer be able to participate in coloring coins of other colors, not even non-reissuable colors.
Transfer transactions
Transfer transactions are used to send colored coins from one address to another. It is also possible to transfer coins of multiple colors in a single transfer transaction. Tagging-based coloring is the most well-known algorithm for this operation.
If colored coins are used as input for transactions that do not follow the transfer protocol, the value associated with their color is lost. Furthermore, their value can also be lost in a malformed transaction.
There are one or more colored inputs in a transfer transaction. Inputs do not need to be of the same color, e.g. "gold" and "silver" can be transferred within one transaction, which is beneficial for peer-to-peer trade. The order of inputs and outputs within a transaction, as it is used for non-ambiguous decoding.
Alternative coloring algorithms
Determining a way to transfer colored coins from one Bitcoin address to another is the most complex part of the colored coins protocol. For transactions with only one input and one output, it is easy to determine that the color of the output coins is the same color that was received by the input address, since a Bitcoin address can only handle a single color value. However, in transactions with multiple inputs and outputs, determining which colored coins of inputs correspond to which outputs become a more complex task. For that, there are several algorithms that propose to solve this problem, each one with its peculiarities.
Order based coloring is the first and simplest coloring algorithm. An intuitive way to understand this algorithm is to consider that the transaction has a width proportional to its total input amount. On the left side there are inputs, each a width proportional to its value, on the right side there are outputs with values proportional to their bitcoin values. Assume, then, that colored water flows in a straight line from left to right. The color of an outlet will be the color of the water arriving at it, or colorless if multiple-color coins arrive at that outlet. A single Bitcoin address cannot handle coins of different colors.
Padded order based coloring is a slightly more complex algorithm than the OBC (Order based coloring) algorithm. In essence, the algorithm has the same principle as the OBC, however, treating each output as containing a pad of a certain number of colorless bitcoins, with the colored coins following them.
Applications
The Bitcoin network's decentralized nature indicates that its security does not need dependence on trusted parties and that its players may operate anonymously provided adequate safeguards are adopted. Colored Coins protocols adoption enables the integration of decentralized stock exchanges and other financial functionality into Bitcoin such as certifying credentials (like academic certificates), or establishing the existence of digital documents.
Smart property: For example, a product rental company can release a colored coin to represent their products, such as a car. Through an application, the company could configure a control message that would send a message signed by the private key that currently has the colored coin. In this way, its users could transfer the vehicle's digital key to each other, by transferring the currency. This protocol feature may be used in land management by indicating ownership of a piece of land with a single or several tokens. The token's information may be used to maintain public registry parameters such as size, GPS locations, year created, and so on. The land administrator may encrypt ownership details such as titles or identification so that only individuals with the right private key can see the information. Anyone with an internet connection can publicly verify and trace the ownership of each token using block explorer software.
Issue of shares: A company can issue its shares through colored coins, taking advantage of the Bitcoin infrastructure to manage activities such as voting, exchange and payment of dividends. Colored coins may also be used to form Distributed Collaborative Organizations (DCOs) and Decentralized Autonomous Organizations (DAOs), which are acting as virtual corporations with shareholders. In such cases, the blockchain may assist in keeping track of a company's ownership structure as well as creating and distributing DCO shares in a transparent and safe manner. Examples: community currency or corporate currency, deposit representation, access and subscription services.
Issue of coupons: A company can issue promotional coupons or loyalty points among its customers in the form of colored coins.
Digital collectibles: Decentralized management of digital resources. Similar to how collectors acquire and sell paintings, colored coins enable managing digital resources in a similar way, such as e-books, music, digital games and software, guaranteeing ownership of the resource to the owner of the coin.
As long as the provider's identity is protected by the legal framework, colored coins may be used to transfer any digitally transferable right. The circulation is based on a cryptographic signature. The contract and any payments linked to it are recorded on the blockchain using a unique cryptographic key that identifies the rightful owner of the currency. Parties may use an alias to sign up for the protocol under legally permissible circumstances. In reality, the secret cryptographic key enables the system to validate subscribers' digital identities without disclosing any personal information.
Private key holders might then transfer the asset directly to other persons or corporations through a public blockchain.
Users may trade and manage all asset classes in a somewhat decentralized framework with a minute amount of colored Bitcoin, according to marketing literature, rather than needing to send hundreds or even thousands of bitcoins in return for an item or service.
Deterministic contracts: A person or company can issue contracts by pre-scheduling a payment, such as stock options.
Bonds: A special case of a deterministic contract, bonds can be issued with a down payment amount and an installment schedule in bitcoin, another currency or commodity.
Decentralized digital representation of physical resources: It means tying physical resources, such as physical objects, commodities, or traditional currencies, to digital resources and proving ownership of those objects in that way. NFT tokens use this approach, selling ownership of artworks and even living properties.
Сolored coin wallet
Colored coins can be handled through wallets in the same manner as Bitcoin monetary resources can be managed through bitcoin wallets. Wallets are used to manage the addresses associated with each pair of keys (public and private) of a Bitcoin user, as well as the transactions associated with their set of addresses. Rather than dealing with cryptocurrencies, colored coin wallets add a layer of abstraction, managing digital assets, such as stocks, altcoins, which are created on the Blockchain, intellectual property and other resources.
While bitcoin wallets are required to use a unique Bitcoin address for each transaction, colored coin wallets frequently reuse their addresses in order to re-issue coins of the same color.
To issue colored coins, colored addresses must be generated and stored in colored wallets administered by a color-aware client such as Colu or Coinprism.
Protocol implementation
Protocol implementations are associated with wallet software, so that the end user does not have to be concerned about transaction structuring or manual resource manipulation. There is, however, some concern about the interoperability of the existing implementations, as colored coins transactions are operationalized using the variety of different algorithms. Transactions between unsupported wallets may result in the loss of currency coloring features.
Colored coins require a unified wallet that can distinguish between items other than bitcoins. In June 2015, a Torrent-based version of Colored Coins was developed by Colu to cover the protocol's use while Bitcoin has not yet been widely adopted by the market. Making the protocol compatible amongst different Bitcoin implementations is one approach to increase the usage of Bitcoin for digital asset management.
Legal aspects
A smart property or an item with an off-chain identifier that is transferred via blockchain remains subject to legal interpretation. Colored coins and other virtual currency are presently not recognized as evidence of ownership by any government agency in the United States. For financial institutions, the lack of an identifiable identity across on-and off-chain settings is still a barrier.
There's a legal challenge with regard to the transfer of common stock ownership using blockchain. Due to the fact that the rights to receive notifications, vote, receive dividends, and exercise appraisal rights are restricted to registered owners, establishing ownership is likely even more critical for blockchain stock.
Due to the extralegal nature of colored coin transactions such as NFTs, they frequently result in an informal exchange of ownership over the item with no legal basis for enforcement, frequently conferring nothing more than usage as a status symbol.
Limitations
As virtual tokens colored coins cannot compel the real world to meet the obligations made when they were issued. They can represent something external, in the actual world, such as a corporate action or debt repayment obligation. This suggests that they are issued by a person or entity, which carries some level of risk. That the issuer does not comply with its related obligations or there may even be fraud and that those currencies may not represent anything actual.
They are unable to prevent a user from changing the underlying cryptocurrency in a way that destroys the extra information. Using virtual tokens in a transaction that does not conform with the rules of colored currencies (stricter than the rules of blockchain transactions and not mandated by it) destroys the additional meaning, leaving only the token’s monetary worth on the blockchain.
It is impossible to store the semantics of information indicating what a token represents. For instance, the blockchain can record the number of concert tickets that have been issued and the addresses of their owners, but it cannot encode the fact that they represent allowed access to a specific concert at a specific time. Metadata storage and processing require an external system, such as Open-Transactions. Open-Transactions is a free software library that implements cryptographically secure financial transactions using financial cryptographic primitives. It can be utilized to issue stocks, pay dividends, purchase and sell shares, etc.
The speed of transactions and the capabilities of the smart contract procedures utilized by virtual tokens are equivalent to those of the blockchain they are based on.
Due to the nature of the Bitcoin host network, adding an additional layer is neither simple nor scalable. Additionally, it inherits all of the information security and safety concerns of the host blockchain. Developing a comprehensive protocol that incorporates asset issuance and native tracking may be a more rigorous and scalable method for creating a blockchain-based asset-tracking system.
Concerns
Opposition to the use of Colored Coins for the treatment of abstracted resources on Bitcoin mainly originates in the financial and banking sectors. It is argued that the proof-of-work blockchain-based security system cannot be exported to a regulated financial resolution environment. As a result, there is no legal framework for Colored Coins' transactions. Finally, there are some regulatory concerns with the coin coloring method. According to institutions that criticize the decentralized transaction system, the legal effect of an individual or entity transferring ownership of a given object to another individual or entity through Bitcoin abstractions is still uncertain.
See also
Bitcoin
Blockchain
Digital currencies
Non-fungible token
Bitcoin network
Smart contract
Altcoins
References
Cryptocurrencies
Bitcoin
Blockchains
Cryptocurrency projects
Cryptography
Payment systems
Currencies introduced in 2012
2012 establishments
Cross-platform software
Decentralization
Application layer protocols
Free and open-source software
Free software programmed in C++ | Colored Coins | [
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"Applied mathematics",
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74,836,316 | https://en.wikipedia.org/wiki/Otto%20Schiff%20%28humanitarian%29 | Otto Moritz Schiff CBE (8 May 1875 in Frankfurt – 15 November 1952 in London) was a British Jewish banker and philanthropist. For his work with refugees and for public services, he successively received the OBE (1920), MBE (1924) and CBE (1939). He was posthumously recognised as a British Hero of the Holocaust.
Life and activity
Otto Schiff was the son of a banker and a nephew of Jacob Schiff (1847–1920), a German-born New York investment banker. In 1896, at the age of twenty-one, he immigrated to London, where he became a partner in the merchant banking firm Bourke, Schiff and Co. His younger brother Ernst followed. Together, in the First World War, the brothers ran shelters for Belgian refugees. Ernst Schiff received an MBE as manager of the Poland Street Refuge for Belgian Refugees in 1918.
From 1927 to 1948, Schiff was president of the Jews' Temporary Shelter in City of London. This originally served as the first port of call for Jews from Eastern Europe who fled from there to Great Britain to avoid political persecution by the Russian Tsarist regime and later by the Bolsheviks.
From 1933 Schiff served as chairman of the Jewish Refugees Committee, which was created in March of that year (German-Jewish Aid Committee from 1938, operating under the original name again from 1939). He helped numerous Jewish refugees to settle in Britain. He convinced the British government to allow the entry of Jewish refugees in return for the assurance that any costs would not be borne by the state, but would be borne by the Jewish communities and organizations.
In 1920 Otto Schiff became a Member of the Order of the British Empire for his work with war refugees.
In 1924 he became an Officer of the Order of the British Empire for public services. He, as chairman of the German Jewish Aid Committee, became a Commander of the Order of the British Empire in the 1939 Birthday Honours.
In 1940, Schiff was placed on 'the Black Book' ( "Special Search List Great Britain"), a list of 2,820 persons who were to be arrested by the SS in the event of a German occupation of Britain.
In 2018 Schiff was posthumously awarded the medal of a British Hero of the Holocaust.
See also
Belgian refugees in Britain during the First World War
Jewish refugees from German-occupied Europe in the United Kingdom
Joan Stiebel
References
1875 births
1952 deaths
British philanthropists
Businesspeople from Frankfurt
Commanders of the Order of the British Empire
German emigrants to the United Kingdom
Otto Schiff
British investment bankers
Rescue of Jews during the Holocaust
British Heroes of the Holocaust
20th-century British Jews
19th-century British Jews | Otto Schiff (humanitarian) | [
"Biology"
] | 537 | [
"Rescue of Jews during the Holocaust",
"Behavior",
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74,836,769 | https://en.wikipedia.org/wiki/Julie%20Diani | Julie Diani is a French academic specialised in the characterization and simulation of polymeric materials. She is the CNRS Research Director at École Polytechnique’s Solid Mechanics Laboratory, and holder of the Arkema Design and Modeling of Innovative Materials Chair.
Education
Diani earned a B.S. in Applied Mathematics and her S.M. Degree in Mechanical Engineering at the Pierre et Marie Curie University. She completed her doctoral degree in Materials Science and Engineering at Ecole Normale Superieure de Cachan.
Career
She joined CNRS in 2000. From 2004 to 2006, she was a visiting researcher at the University of Colorado, Boulder.
Diani's most cited works include a review of the Mullins effect and a constitutive model for Shape-memory polymers.
Personal life
Diani is the daughter of two math teachers, and she does Judo and biking.
Awards and recognition
2015 - Sparks–Thomas award from the ACS Rubber Division
References
Polymer scientists and engineers
Women materials scientists and engineers
Year of birth missing (living people)
Living people
Pierre and Marie Curie University alumni
École Normale Supérieure alumni
Research directors of the French National Centre for Scientific Research | Julie Diani | [
"Chemistry",
"Materials_science",
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"Polymer chemistry",
"Women materials scientists and engineers",
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74,837,310 | https://en.wikipedia.org/wiki/Gharial%20conservation%20in%20Pakistan | The Gharial (Gavialis gangeticus) is classified as a critically endangered species. Its last sighting in Pakistan was reported in 1985. However, there have been recent reports indicating that the Gharial has been sighted once again, specifically in the Punjab region of Pakistan. After reported sightings, the "Gharial Wildlife Sanctuary" has been designated as a protected area under the Punjab Protected Areas Act of 2020.
Recent Sightings
In May 2023, sightings of the Gharial were shared on social media, prompting the World Wildlife Fund (WWF) Pakistan's wildlife team to conduct an investigation. Following their survey, they confirmed the presence of Gharials in the area, including juvenile individuals. This event marked the first verified sighting of the species in Pakistan after a presumed absence of three decades.
A survey team has confirmed the presence of about 10 gharials, including six baby crocodiles, in the Ganda Singh Wala area of the river. The team spotted a gharial measuring roughly 14 feet in length and two feet in width. There is speculation that these crocodiles might have migrated from India after the floods last year and have now started to reproduce in this area. Experts have noted that gharials mainly feed on fish and do not pose a threat to humans.
Conservation Efforts
In response to these sightings, WWF-Pakistan is collaborating with the Forestry, Wildlife and Fisheries department, Punjab and other partners to enhance conservation efforts for the Gharial. The primary objective is to guarantee the newly discovered population not only survives but also thrives in its habitat through dedicated conservation measures.
The conservation plan encompasses onsite monitoring in collaboration with security authorities. The main emphasis will be on executing efficient conservation measures and safeguarding the Gharials' habitat. This involves ensuring appropriate water quantity and quality, as well as managing ongoing fishing activities to protect their habitat effectively.
Reintroduction Program
Pakistan has formally requested the transfer of hundreds of Gharial crocodiles from Nepal as part of an initiative to reintroduce this species. The government aims to reintroduce Gharials into the Nara Canal wetland system to enhance its biodiversity. Additionally, this reintroduction program is anticipated to generate income for local communities through wildlife tourism, presenting a potential economic opportunity tied to conservation efforts.
Challenges
While there is local support for the reintroduction of Gharials in Pakistan, the request made to Nepal is confronted by several challenges. These hurdles encompass financial constraints and reservations regarding whether Pakistan has adequately addressed the conditions that initially resulted in the local extinction of the Gharial species. These concerns pose obstacles to the successful transfer and reintroduction of Gharials from Nepal to Pakistan.
References
Endangered species
Wildlife conservation in Pakistan | Gharial conservation in Pakistan | [
"Biology"
] | 553 | [
"Biota by conservation status",
"Endangered species"
] |
74,838,640 | https://en.wikipedia.org/wiki/TERN-501 | TERN-501 is a selective thyromimetic drug that is being developed for the treatment of non-alcoholic fatty liver disease.
References
Thyroid hormone receptor beta agonists
Chloroarenes
Oxadiazoles
Pyridazines
Anilides
Isopropyl compounds
Experimental drugs developed for non-alcoholic fatty liver disease | TERN-501 | [
"Chemistry"
] | 69 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
74,838,922 | https://en.wikipedia.org/wiki/Ballet%20and%20fashion | Throughout its history, the costume of ballet has influenced and been influenced by fashion. Ballet-specific clothing used in productions and during practice, such as ballet flats, ballerina skirt, legwarmers, and leotards have been elements of fashion trends. Ballet costume itself has adapted aesthetically over the years, incorporating contemporary fashion trends while also updating fabrics and materials to allow for greater freedom of movement for the dancers. The classic ballerina costume with a tutu and pointe shoes debuted in the 1830s. Ballet costume is marked by the innovation in lightweight materials such as tulle, chiffon, and organza.
In the early 20th century, productions by the Russian ballet company Ballets Russes had a large influence on fashion design in Paris. Designers incorporated ballet-inspired themes in their creations. Designers that have been influenced by ballet include Christian Dior, Elsa Schiaparelli, Paul Poiret, Coco Chanel, Jacques Fath, Jeanne Lanvin, Madeleine Vionnet, Molly Goddard, and Simone Rocha.
History
17th and 18th centuries
Ballet costume originated in the 17th-century royal courts of Italy and France, including that of Louis XIV. Early costume designs in ballet productions were based on court dress, though more extravagant. All of the performers in early ballets were men, with boys performing the female roles en travesti. In the 18th century, as ballet became professionalized and moved from the courts to the theaters, women joined the ranks of ballet dancers. Traditionally, dancers wore heeled shoes, until the 1730s, when Paris Opera Ballet dancer Marie Camargo was one of the first to wear ballet slippers instead. She also wore midcalf-length skirts and close-fitting drawers.
Until the late 18th century, lead dancers in a ballet company often wore masks. The practice was abandoned after balletmaster Jean-Georges Noverre and choreographer Maximilien Gardel dispensed with them, seeing how they impeded the dancers' movements and the ability to see their facial expressions. Similarly, cumbersome hairstyles and wigs that were not conducive to ballet movements were largely excluded from the stage.
19th century
Ballet costume has an essential role in facilitating the movements of dancers while "maintaining the integrity of the line of the body". Technical and visual problems with ballet costume are avoided through the creation of well-designed and proportioned clothing. Ballet costume has evolved alongside choreography to allow for the display of musculature.
In the late 18th and early 19th centuries, the industrialisation of cotton manufacturing led to the widespread availability of cheap cotton fabrics such as tulle, muslin, tarlatan, and gauze. Ballet companies were able to produce new costumes for each production.
Ballet costume during the early 19th century mirrored the women's fashions of the era. Ballet appropriated high fashion elements, including full sleeves, revealing decolletage, fitted waist, bell-shaped skirts, and more diaphanous fabrics. Adaptations such as lighter fabrics and raised hemlines allowed dancers greater freedom of movement and the audience to appreciate the dancer's footwork. As clothing became less restricted, the natural silhouette was emphasized.
Pointe shoes were invented around 1820 and the archetypal look of the romantic ballerina was provided by Marie Taglioni in the 1832 ballet La Sylphide. Her fitted décolleté bodice, diaphanous calf-length tulle skirt, and satin pointe shoes laced around the calf provided the template for the ballerina costume. Her ballerina skirt was a shortened version of the 1830s fashion gown. She was the first ballerina to dance a full-length ballet en pointe, and became very popular with images of her widely published. Following her fame, luxury fabrics and corsets were produced bearing the names Taglioni or La Sylphide.
As ballet emerged as entertainment for aristocrats, the ballet dancer became principally a woman's profession and the reputation of ballerinas declined in the later 19th century. The feminization of ballet was due in part to a larger male audience. Ballerinas were frequently poor, marginalized members of society, regarded more as workers than artists. They were often subject to the attention of lascivious men, sexually commodified, and sometimes forced into prostitution.
Styles of ballet costume were influenced by the popularity of romantic narratives of regional and supernatural folklore, such as the sylph motif. Towards the end of the 19th century, the classical tutu was codified in St. Petersburg during the era of ballet master Marius Petipa. During this time, the tutu was shortened and the boxes of pointe shoes were reinforced.
20th century
Ballets Russes
Beginning in 1909, the Russian ballet company Ballets Russes brought high classical ballet to the West, principally in Paris. Fashion designers and haute couture were inspired by the influential ballet company. Léon Bakst was the troupe's principal costume designer in the early 1900s. His designs inspired Paul Poiret, who also designed for the company. Trends in Parisian fashion were adapted into ballet costume by Ballets Russes. The dress from Stravinsky's 1910 ballet The Firebird was influential in fashion design. The Orientalist aesthetic of Ballets Russes influenced the boldly colored trousers and harem skirts and trousers of fashion designer Paul Poiret. Coco Chanel designed costumes for the 1924 ballet Le Train Bleu and went on to create ballet-inspired fashions.
1920s
Ballets Russes continued to have an influence on fashion into the 1920s. A turning point in the relationship between ballet and fashion was Sergei Diaghilev's 1921 production of The Sleeping Beauty. The ballet's use of light pastels such as lilac influenced color trends in fashion. The production's bluebird blue costumes inspired Elsa Schiaparelli to create her signature color "sleeping blue". French fashion designer Jeanne Lanvin's full-skirted robe de style dresses of the mid-1920s and Madeleine Vionnet's Ballerina dress both had inspiration in the ballerina costume. According to ballet historian Ilyana Karthas, during the 1920s images of femininity were promoted in the context of athleticism, exercise, and the physical body.
Italian fashion designer Elsa Schiaparelli also collaborated with the Ballets Russes, inspired by the surrealistic costuming of Giorgio de Chirico in Diaghilev's 1929 production of Le Bal.
1930s and balletomania
The 1932 ballet Cotillon was choreographed by George Balanchine and starred Tamara Toumanova, one of the first Baby Ballerinas. Costumes from the production were designed by Christian Bérard and made by Barbara Karinska, who innovated the layering of differently colored tulle. Bérard's designs inspired the glittering tulle gowns that Coco Chanel designed in the 1930s.
Since the 1930s, ballet costume has inspired the fashion trends of fitted bodices and bell-shaped silhouettes. Materials used for tutus, such as chiffon, silk tulle, and organza were later incorporated into fashion collections. The romantic-era tutu style also had an influence on the design of gowns. In the 1930s, longer dresses with tulle skirts became fashionable, as exemplified by Coco Chanel's 1937 "Etoiles" dress. which drew inspiration from Balanchine's 1932 ballet Cotillon.
The balletomania trend of the 1930s and 1940s had a marked influence on fashion. In the early 1930s, ballet fashion was frequently featured in magazines. Ballerinas were also employed as models from the 1930s onward.
1940s and 1950s
With the advent of synthetic materials, ballet practice clothing such as leotards and tights became popular as fashion pieces from the 1940s on.
In 1941, former ballet student and fashion editor Diana Vreeland innovated the use of pointe shoes as everyday wear, in part because wartime restrictions did not apply to them. Due to a shortage of leather, fashion designer Claire McCardell commissioned the dance house Capezio to produce a range of ballet flats to match her designs. The ballet flat went on to become everyday footwear.
Designers of high fashion and haute couture collaborated frequently with star ballerinas such as Margot Fonteyn in the 1940s. Couturiers such as Pierre Balmain designed costume for ballet as well as high fashion. Designers Christian Dior and Jacques Fath were both influenced by ballet costume. Costumes designed by Fath for the 1948 film The Red Shoes featuring the ballerina Moira Shearer were also influential in creating a demand for ballet-inspired fashion.
The fashion house Balmain, founded by Pierre Balmain, and the designer Cristóbal Balenciaga drew inspiration from the aesthetics of ballet costume. The use of feathers in the ballet costumes of ballerina-bird characters in productions of The Firebird, The Dying Swan, and Swan Lake was also mimicked in fashion.
1960s and 1970s
During the late 1960s and 1970s, the clothing brand Danskin produced leotards that could be worn for dance as well as streetwear. Fashion designer Bonnie August popularized the look of unitards worn under wrap skirts in the mid-1970s. Ballet-inspired fashion designs experienced a revival in the 1970s during the disco era while athleisure incorporated mainstays of ballet rehearsal clothing such as leotards.
In the 1970s, Dance Theatre of Harlem founder Arthur Mitchell decided that dancers' tights and shoes should match their skin tone. The dance apparel company Capezio produced brown pointe shoes for the company.
A 1976 collection from Yves Saint Laurent paid homage to the Ballets Russes and Serge Diaghilev.
21st century
During the early 2000s, a ballet-inspired fashion trend drawing heavily on warm-up clothing was called "dancer off-duty". In the 2000s, ballet fashion was popularized on film and television through the film Black Swan and Carrie Bradshaw's iconic tulle skirt from Sex and The City. The 2000s saw the lines of companies that produce pointe shoes broaden to include skin tones of people of color, including Black women in ballet.
A 2020 exhibition Ballerina: Fashion's Modern Muse was held at The Museum at FIT.
Balletcore
A resurgence in interest in ballerina-inspired fashion in the mid-2020s came to be known as balletcore. The fashion trend drew inspiration from the graceful and elegant aesthetic of ballet dancers, which has been called "hyper-feminine" and embraces both comfort and body movement in a context that explores femininity. The popularity of the trend has been attributed to Gen Z's obsession with nostalgia.
Balletcore continued fashion's use of traditional ballet costumes such as ballet flats, pointe shoes, ballerina skirts, leotards, and tights. Athleisure fashions incorporate dancewear elements such as legwarmers, which are often layered or combined with tie skirts and wrap tops, as well as delicate accessories like ribbon chokers and ballet slipper-inspired shoes. Balletcore continued to rely on lightweight materials such as tulle and satin, organza, sheer fabrics, mesh, and spandex. Ballet-inspired fashion continues to emphasize soft pastel hues such as pink, peach, baby blue, lilac, and light neutral colors.
In the 2020s, ballet-inspired elements have increased the popularity as a part of the collections of Rodarte and Miu Miu, as well as those of fashion designers Molly Goddard and Simone Rocha. While principally a phenomenon in women's clothing, ballet has also influenced designs in men's wear and workout wear, with brands creating collections that combined functionality with a balletic aesthetic.
See also
History of ballet
History of fashion design
Music and fashion
References
Further reading
Fashion
Fashion design
Fashion industry
Fashion
History of fashion
Internet aesthetics | Ballet and fashion | [
"Engineering"
] | 2,388 | [
"Design",
"Fashion design"
] |
74,839,285 | https://en.wikipedia.org/wiki/Sarah%20Peluse | Sarah Anne Peluse is an American mathematician specializing in arithmetic combinatorics and analytic number theory, and known for her research on generalizations of Szemerédi's theorem on the existence of polynomial progressions in dense sets of integers. She is an assistant professor and LSA Collegiate Fellow in the Department of Mathematics at the University of Michigan.
Education and career
Peluse's interest in mathematics was sparked by a sixth-grade teacher using the Socratic method. After skipping seventh grade and running through all of the mathematics available at her local high school and community college, she enrolled at Lake Forest College in Illinois at age 15. The mathematics on offer there lasted her only for another two years, so she transferred to the University of Chicago, with Paul Sally and later Maryanthe Malliaris as mentors. She also became a member of the University of Chicago track and field team, which competed at two national championship meets, and she was recognized as a Division III All-Academic Athlete by the NCAA. She earned a bachelor's degree in mathematics in 2014.
Peluse completed her Ph.D. at Stanford University in 2019. Her dissertation, Bounds for sets with no nontrivial polynomial progressions, was supervised by Kannan Soundararajan. She became an NSF Postdoctoral Fellow at the University of Oxford, and then a Veblen Research Instructor at Princeton University and the Institute for Advanced Study, before taking her present position as a faculty member at the University of Michigan.
Recognition
As an undergraduate, Peluse won the 2014 Alice T. Schafer Prize of the Association for Women in Mathematics for her work in mathematics.
Peluse was the recipient of the 2022 Dénes König Prize, given at the SIAM Conference on Discrete Mathematics, for her work on polynomial generalizations of Szemerédi's theorem. She was also a 2022 recipient of the Maryam Mirzakhani New Frontiers Prize, associated with the Breakthrough Prize in Mathematics, "for contributions to arithmetic combinatorics and analytic number theory, particularly with regards to polynomial patterns in dense sets".
She won the 2023 Salem Prize (joint with Julian Sahasrabudhe) for contributions to additive combinatorics and related fields, including her work on quantitative density theorems for polynomial configurations in arithmetic progressions, which have found application in discrete harmonic analysis and ergodic theory.
References
Year of birth missing (living people)
Living people
21st-century American mathematicians
Combinatorialists
University of Chicago alumni
Stanford University alumni
University of Michigan faculty
21st-century American women mathematicians
Additive combinatorialists | Sarah Peluse | [
"Mathematics"
] | 527 | [
"Combinatorialists",
"Combinatorics"
] |
74,839,346 | https://en.wikipedia.org/wiki/Copyright%20infringement%20and%20social%20media | Copyright infringement and social media involves the use of social media platforms to distribute copyrighted material illegally, thus copyright infringement.
Background
Content posted to social media platforms located in the United States is regulated by the Digital Millennium Copyright Act, a foundational federal statute absolving social media companies from liability for content posted on their platforms if they make a reasonable effort to remove violative content. Additionally, social media companies are protected by Section 230 of the Communications Decency Act; Section 230 does not provide legal protection for copyrighted content.
History
Under Elon Musk, several recent films have been illegally rerecorded and posted to Twitter, including Avatar: The Way of Water (2022), The Super Mario Bros. Movie (2023), Shrek the Third (2007), The Flash (2023), and Top Gun: Maverick (2022).
Film and television industry
Social media platforms have been used as vectors to host film and television episodes. A report from Business Insider released in 2018 found multiple groups, some with upwards of tens of thousands of members, hosting copies of films directly onto Facebook, including The Greatest Showman (2017), Transformers: The Last Knight (2017), and cam copies of Ant-Man and the Wasp (2018). Facebook told Business Insider that it would not take down the groups, stating that the responsibility of taking down the content is the responsibility of the rights holder.
Segments from films and television episodes have been repackaged on TikTok, resulting in a renaissance for older television series and films such as Temple Grandin (2010), The Good Doctor, and Malcolm in the Middle. The phenomenon has also benefited newer films and television series; a single clip from Fall (2022) attracted over one hundred million views on TikTok, while a leak of HBO's revival of Clone High received significant attention on the platform. TikTok users organically promoted the reality hoax sitcom Jury Duty that received limited attention.
Distributors have utilized social media to promote their own television series, such as Peacock's Killing It and Bupkis. In 2021, HBO Max released free episodes of several television series on the service on Snapchat, including the Gossip Girl reboot, The Flight Attendant, Lovecraft Country, and Game of Thrones. Apple TV+ released the first episode of Silo onto Twitter after the service allowed longer videos; Twitter chief executive Elon Musk praised the decision. Paramount Pictures uploaded the entirety of Mean Girls (2004) onto TikTok in October 2023.
For the 2023 New Zealand general election, the Green Party used footage from Barbie (2023) to criticize the National and Labour parties. The Green Party confirmed that they did not have copyright permission from Warner Bros. The Green Party later removed these videos due to copyright violations. They have not commented on whether this decision was made due to request by Warner Bros.
Sludge content
The use of copyrighted material on TikTok has resulted in a form of media known as "sludge content", which features attention-grabbing content alongside copyrighted material. The 2012 endless runner mobile game Subway Surfers and the adult animated television series Family Guy are commonly included. The concept of sludge content originates with methods used to subvert copyright detection tools, particularly on Family Guy compilations on YouTube. Editing techniques such as frequent jump cuts, unrelated clips, and cropping have increased the longevity of copyright violating videos on YouTube. TikTok users have additionally used the format to splice TikTok videos made by other users.
Music industry
The Russian social media platform VK has been noted for being a "notorious marketplace" for music piracy since 2010, according to the Office of the United States Trade Representative. The Recording Industry Association of America and International Federation of the Phonographic Industry chief executive Frances Moore have spoken out against music piracy on VK. In December 2013, VK founder Pavel Durov stated that he would abide by takedown requests. Sony Music Russia, Universal Music Russia, and Warner Music UK filed separate lawsuits against VK in Saint Petersburg and Leningrasky Region Arbitration Court in April 2014 seeking million in damages.
Former U.S. president Donald Trump's use of copyrighted music in his presidential campaigns has resulted in multiple lawsuits. In 2020, Eddy Grant sued Trump for using "Electric Avenue" in a campaign video. During the 2014 New Zealand general election, the National Party illegally used Eminem's "Lose Yourself". The party was ordered to pay in 2018.
User content
United States District Court for the Southern District of New York judge Alison Nathan ruled in January 2013 that Agence France-Presse (AFP) and The Washington Post infringed on freelance photojournalist Daniel Morel's copyright by reuploading an image Morel had posted to Twitter of the 2010 Haiti earthquake. In Agence France Presse v. Morel (2010), AFP argued that Twitter's terms of service allowed the agency to reuse the photo and upload it to Getty Images, where The Washington Post used four of Morel's photographs. The press outlets would have been able to use the photographs if it was embedded within their articles.
Preventive measures
In April 2016, Facebook released Rights Manager, a tool allowing rights holders to identify copyrighted content. Rights Manager was expanded in April 2017 to automatically block content, monitor video metrics, and receive a portion of the video's revenue if it has advertisements attached to it. The company acquired the video detection company Source3 in July 2017.
Analysis
Cornell University behavioral scientist Gordon Pennycook stated that the choice to watch media on TikTok mirrored consumer habits of "constant stimulation".
References
Further reading
Copyright infringement
Social media | Copyright infringement and social media | [
"Technology"
] | 1,163 | [
"Computing and society",
"Social media"
] |
74,839,988 | https://en.wikipedia.org/wiki/Lanifibranor | Lanifibranor is a pan-PPAR (peroxisome proliferator-activated receptor) receptor agonist and is the first medication that targets PPAR-alpha, PPAR-beta, and PPAR-gamma simultaneously. As of 2023, it is in a phase III trial for nonalcoholic steatohepatitis; its advantage over other drugs that are in phase III trials for the same condition is that it has shown improvements in both steatohepatitis and fibrosis.
References
PPAR agonists
Indoles
Benzothiazoles
Sulfonamides
Carboxylic acids
Chloroarenes
Experimental drugs developed for non-alcoholic fatty liver disease | Lanifibranor | [
"Chemistry"
] | 146 | [
"Carboxylic acids",
"Functional groups"
] |
74,840,353 | https://en.wikipedia.org/wiki/CFHTWIR-Oph%2098%20b | CFHTWIR-Oph 98 B is a substellar object, either an exoplanet or a sub-brown dwarf that orbits CFHTWIR-Oph 98 A, a M-type brown dwarf. The pair form a binary system. The primary is a M9–L1 dwarf and the secondary is an L dwarf with a spectral type of L2–L6. Both spectral types are estimated from photometry. The pair is separated by 200 astronomical units and has a low gravitational binding energy. The primary Oph 98A has a spectrum taken in 2012 with VLT/ISAAC, matching a spectral type of M9.75 and from Spitzer photometry and near-infrared photometry it is surrounded by a class II disk. This disk has a mass of 0.135 according to a study using SED-modelling.
Formation
It orbits a star but its formation as an exoplanet is challenging or impossible. If its formation scenario is known, it may explain the formation of Planet Nine. Planetary migration may explain its formation, or it may be a brown dwarf.
See also
List of exoplanets discovered in 2020
Brown dwarf
2MASS J11193254–1137466 AB
Notes
References
Ophiuchus
Exoplanets discovered in 2020
Exoplanets detected by direct imaging | CFHTWIR-Oph 98 b | [
"Astronomy"
] | 273 | [
"Ophiuchus",
"Constellations"
] |
74,842,358 | https://en.wikipedia.org/wiki/Daisho%20%28Drosophila%20peptide%29 | Daisho (Dso) is an antimicrobial peptide gene family of the fruit fly Drosophila melanogaster. Two Daisho genes (Dso1, Dso2) are encoded in tandem in the fruit fly genome, one shorter than the other. This pair of genes with different length was named "Daisho" in reference to Daisho Japanese swords, which come in pairs with one shorter than the other.
The Daisho genes are regulated by Drosophila Toll-like receptor signalling. Daisho peptides protect flies against filamentous fungi, particularly Fusarium and also Aspergillus. Daisho peptides are part of the Drosophila antifungal effector peptide response, which includes the gene families Bomanin, Drosomycin, Metchnikowin, and Baramicin.
References
Peptides
Antifungals | Daisho (Drosophila peptide) | [
"Chemistry"
] | 179 | [
"Biomolecules by chemical classification",
"Peptides",
"Molecular biology"
] |
74,842,543 | https://en.wikipedia.org/wiki/Latil%20KTL | The Latil KTL is an all-wheel drive tractor produced by the French manufacturer Latil. It was used as a commercial as well as a military tractor.
History
The Latil KTL tractor was introduced in 1929. In October of that year, it was presented in the United Kingdom and, by early 1931, it was being imported into the country. By 1932, it started to be assembled locally under licence by the British company Shelvoke and Drewry with some minor modifications.
From 1932 onwards, the KTL was tested by the French military as a replacement for the earlier Latil TL tractor for towing the 105 L 13 canon, as the previous tractor was considered too slow. In 1934, The military finally commissioned the K TL4, a KTL with extended wheelbase, which was still slow for that usage. About 163 were built.
In 1934, another KTL-based vehicle with extended wheelbase, the G TL3 prototype, was tested as a hauler for the 75 CA anti-aircraft gun, but it had a high centre of gravity and a narrow track relative to its wheelbase, which made it lack stability and off-roading capabilities. In 1937, the design was definetively abandoned. The French military adopted another Latil model, the Latil M2 TZ, and various trucks, among them the Berliet GDLS 30.
Technical details
The main engine used for the tractor is the K, an inline-four petrol engine with a 90 mm bore and a 130 mm stroke, giving a displacement of 3,308 cc. Its maximum power is at 1,900 rpm. Its fiscal power is rated at 13 CV. As an optional, the KTL could be equipped with not specified diesel and gasifier-running engines.
The gearbox is a 3-speed manual unit with a transfer case giving 6 forward speeds and 2 reverses. The differential system can lock the drive on any axle through a lever next to the driver's seat. The tractor has a four-wheel steering system. The wheels could be mounted with retractable spuds for improving grip on some surfaces.
For commercial use, the KTL was offered in two versions: agriculture/forestry tractor and road tractor, which mainly differ on bodywork and hauling equipment. They can haul between 5 and 10 tonnes, depending on version. Both have the same dimensions: a (main) length of a height (without roof) of , a width of , a track of . The wheels have the same size both on front and rear: x .
The tractor's wheelbase is . Its weight (without equipment) is over 2 tonnes. It has drum brakes. Suspension is by long straight leaf springs.
K TL4 and G TL3
The K TL4 is a version of the KTL with a wheelbase extended to . For military use, it was offered in two versions: a tractor for cannon on pivot and an ammunition-carrying tractor with extended bodywork. Both have a length of , a height of (with roof) and a track of . They differ in width: the cannon on pivot version is and the ammunition-carrying is . The K engine in military configuration delivered . The payload is . The tractor's top speed is 35 km/h.
The G TL3 had a wheelbase of .
Latil JTL
The Latil JTL is a similar contemporary tractor with the J engine, an inline-four petrol unit with a 85 mm bore and a 130 mm stroke. Its fiscal power is rated at 11 CV.
The tractor can haul the same as the KTL (5 to 10 tonnes). It was offered with the same variants.
References
Citations
Bibliography
Vehicles introduced in 1929
Tractors
Vehicles of France | Latil KTL | [
"Engineering"
] | 765 | [
"Engineering vehicles",
"Tractors"
] |
74,842,686 | https://en.wikipedia.org/wiki/Vanishing%20Indian | The Vanishing Indian or Vanishing Indian Myth is a stereotype regarding the depiction of Indigenous people, generally in the Americas, although the concept is found elsewhere as well, that they either are extinct or are destined to go extinct.
Common forms
A common expression in everyday speech is a form of "you can't be Indian, Indians are extinct". Another form is in the discussion of disappearance as inevitable, beginning this narrative in the early days of colonization. It is a common theme in the arts and media as well, that dates back to early colonial times.
Relationship to 'paper genocide'
A paper genocide occurs when members of a group are removed from all records, thereby validating the belief that the group is extinct and causing harm to further generations.
See also
Reel Injun
Playing Indian
Stereotypes of Indigenous peoples of Canada and the United States
Blood Quantum
Urban Indian
Aboriginal Tasmanians
Paper genocide
Tribal disenrollment
Indian termination policy
References
Further reading
External links
Stereotypes of Native American people
Stereotypes
Discrimination
Ethnic and racial stereotypes in the United States | Vanishing Indian | [
"Biology"
] | 205 | [
"Behavior",
"Aggression",
"Discrimination"
] |
74,842,857 | https://en.wikipedia.org/wiki/Palamuru-Rangareddy%20Lift%20Irrigation%20Scheme | The Palamuru-Rangareddy Lift Irrigation Project (PRLIP) is an irrigation project in the state of Telangana, India. The project aims to make 12.3 lakh acres of parched lands in erstwhile combined Mahabubnagar district into fertile lands. The project is built on the Krishna river at a cost of 35,000 crore in Nagarkurnool district. On 16 September 2023, Telangana Chief Minister K. Chandrashekar Rao operationalised the first phase of Palamuru-Rangareddy Lift Irrigation Scheme at Yellur-Narlapur pump house in Nagarkurnool district. The project will change the future of six districts viz, Nagarkurnool, Mahabubnagar, Nalgonda, Rangareddy, Vikarabad in South Telangana.
History
Chief Minister Kalvakuntla Chandrashekhar Rao laid the foundation stone of irrigation project on 11 June 2015. The project aims to divert 70 TMC of flood water from Krishna River at Jurala project.
See also
Kaleshwaram Lift Irrigation Project
R. Vidyasagar Rao Dindi Lift Irrigation Scheme
Mahatma Gandhi Kalwakurthy lift irrigation scheme
References
Dams on the Krishna River
Dams in Telangana
Hydroelectric power stations in Telangana
Inter-state disputes in India
Irrigation projects
Irrigation in India | Palamuru-Rangareddy Lift Irrigation Scheme | [
"Engineering"
] | 271 | [
"Irrigation projects"
] |
74,844,396 | https://en.wikipedia.org/wiki/Simeon%20G.%20Eddins | Simeon G. "Sim" Eddins (May 19, 1861) was a 19th-century farmer and slave trader. He primarily traded in the Middle Tennessee region of the United States, but he also purchased enslaved people in Virginia, and sold people in Alabama. Among the children he bought and sold was nine-year-old Henry McDaniel, who as an adult became the father of Academy Award-winning actress Hattie McDaniel. Sim Eddins was killed in 1861 in a Mississippi River steamboat boiler explosion.
Life and work
Eddins was born in Alabama around 1823. In 1847, "Sim Eddings" purchased three legally enslaved children, ages 11, nine and six, from a Spotsylvania, Virginia farmer named Robert Duerson, and resold them in Fayetteville, Tennessee to a farmer named John McDaniel. The middle child grew up and took the name Henry McDaniel; his daughter Hattie McDaniel in turn grew up to be the first African-American winner of an Academy Award, for her performance as Mammy, an enslaved woman who lived in antebellum Georgia, in Metro-Goldwyn-Mayer's 1939 Gone With the Wind. In 1852, a local paper reported that S. G. Eddins of Fayetteville, Tenn. was one of the newly arrived guests at the City Hotel in Richmond, Virginia. Eddins was a guest at Brown's Hotel in Washington, D.C. in September 1853. In 1854, in Hampton County, Virginia, Eddins bought an enslaved woman named Betsy and one of her children, separating Betsy from her husband and seven other sons, and taking them to another state for resale. In 1902, Betsy White was reunited with her surviving children.
In 1858, Simeon G. Eddins and Alexander D.C. Moore sued each other over the planned sale of a pregnant enslaved woman named Beccy, who had been legally owned by Moore in Marshall County, Tennessee. The issues in dispute included the price, the agreement regarding delivery/pickup/holding of the woman, the additional value of her baby once he was born, whether or not she ran away or was hidden by her legal owner, and who owed who what amount after Beccy's apparent death.
In spring 1859, Eddings placed an advertisement in the Fayetteville (Tenn.) Observer announcing, "Negroes for Sale — I have just arrived from Virginia with FIFTY YOUNG NEGROES, 2 miles west of Fayetteville, consisting of men and women, boy and girls, which are for sale at reasonable prices. I will also exchange families, women with one, two, or three children; for single Negroes, either boys or girls. I, or one of my brothers, may be seen in Fayetteville, during the day, or at home at night. S. G. EDDINGS." The place where Eddins held these 50 people was likely a 380-acre property later described as "two and a half miles from Fayetteville, with a good dwelling-house, a mill, and other valuable improvements. The land being mostly creek bottom is unsurpassed by any in the county in fertility." Some of the "valuable improvements" may have been five "slave houses" counted by the 1860 census enumerator in association with the S. G. Eddins household. Also in May 1859, Eddins was appointed delegate to a Democratic political convention in Nashville. In autumn 1859, Eddins showed a harness mule at the Lincoln County Fair.
In February 1860, the Tennessee General Assembly named Eddins one of seven commissioners of the Fayetteville, Boonshill and Pulaski Turnpike. At the time of the 1860 U.S. federal census in June, S. G. Eddings, occupation "trader," lived in Fayetteville, Lincoln County, Tennessee. He owned real estate valued at , and personal estate valued at . He shared his household with two other men named Eddings, both born in Tennessee, one occupied as a "trader". A. H. Eddings was 31 years old and owned personal property worth $10,000; the youngest, T. T. Eddings was 27 and owned personal property worth $7,000. S. G. Eddins also appears on the 1860 slave schedules for Lincoln County as the legal enslaver of 40 people. Of the 40 enslaved people associated with S. G. Eddins, 11 were designated as "fugitives from the state," including a 13-year-old, a 12-year-old, a seven-year-old, two five-year-olds, and a one-year-old. Three enslaved teenagers were associated with the neighboring household of one Hugh Eddins. In January 1861, Eddins offered up number of people for sale in Greensboro, Alabama, including "six girls from 8 to 11 years old, very likely."
Death
In May 1861, Eddins was apparently aboard the steamship Kentucky on the Mississippi River near Columbia, Arkansas, when it suffered a boiler explosion. The Louisville Courier-Journal included Eddins on the casualty list: "S. G. Edings, Fayetteville, Tenn., badly scalded; will die." The Vicksburg, Mississippi Daily Evening Citizen reported that among those killed was "—— Edding, negro trader, Tennessee." The greviously injured Eddins, along with the injured Little brothers and other victims of the explosion, were transferred to another steamboat and taken to Greenville, Mississippi for medical attention.
In June 1861, Jacob Vance and A. H. Eddins published a notice in the Fayetteville Observer that they were administrators of the S. G. Eddins estate and that claims against the estate should be presented to them. In December 1861 the administrators listed for sale 140 stock hogs, eight work mules, three head of horses, 20 head of cattle, and 37 likely negroes.
In 1875, lands that had once belonged to Simeon G. Eddins, deceased, were to be sold to satisfy a judgment.
See also
List of American slave traders
Slave markets and slave jails in the United States
Slave quarters in the United States
History of slavery in Tennessee
References
1820s births
1861 deaths
19th-century American farmers
19th-century American slave traders
Accidental deaths in Mississippi
Deaths from explosion
History of slavery in Tennessee
People from Fayetteville, Tennessee
American slave owners
Year of birth uncertain | Simeon G. Eddins | [
"Chemistry"
] | 1,343 | [
"Deaths from explosion",
"Explosions"
] |
74,844,675 | https://en.wikipedia.org/wiki/Nanomaterials%20and%20cancer | Nanomaterials have gained significant attention in the field of cancer research and treatment due to their unique properties and potential applications. These materials, typically on the nanoscale (measuring less than 100 nanometers), offer several advantages in the fight against cancer.
Use in cancer treatment
Here are some ways nanomaterials are used in cancer treatment:
Drug delivery systems: Nanoparticles can be loaded with anticancer drugs, improving drug solubility, stability, and targeted delivery to cancer cells. This enhances the drug's therapeutic effect while reducing side effects on healthy tissues.
Photothermal therapy: Certain nanoparticles, like gold nanoparticles or carbon nanotubes, can absorb light and convert it into heat. This property is harnessed for photothermal therapy, where these particles are targeted to cancer cells and then heated with laser light, causing localized cell damage and cell death.
Photodynamic therapy: Nanoparticles can be used as carriers for photosensitizing agents. When exposed to light of a specific wavelength, these agents generate reactive oxygen species, which can kill cancer cells or damage their structural components.
MRI contrast agents: Nanomaterials with magnetic properties, such as iron oxide nanoparticles, are used as contrast agents in magnetic resonance imaging (MRI). They can help detect and visualize tumors with high precision.
Radiotherapy enhancers: Some nanoparticles, like high atomic number nanoparticles, can enhance the effects of radiation therapy. They increase the absorption of ionizing radiation, leading to improved tumor cell damage while sparing healthy tissue.
Diagnostic tools and medical factory: Quantum dots and other nanomaterials are used in cancer diagnostics. They can be designed to specifically target cancer biomarkers, allowing for highly sensitive and accurate detection of cancer cells or molecules associated with cancer.
Gene therapy: Nanocarriers, such as lipid nanoparticles or polymer nanoparticles, can deliver therapeutic genes to cancer cells. This approach aims to modify the genetic makeup of the cancer cells, either to inhibit their growth or sensitize them to other treatments.
Immunotherapy enhancement: Nanomaterials can be used to enhance the effectiveness of immunotherapies. They can serve as carriers for immune checkpoint inhibitors, vaccines, or other immunomodulatory agents.
Intracellular drug delivery: Some nanoparticles are designed to penetrate cancer cells and release therapeutic payloads directly into their interior. This can be especially valuable for targeting resistant or hard-to-reach cancer cells.
Personalized medicine: The versatility of nanomaterials allows for the development of personalized cancer therapies. Tailoring nanoparticle properties to match an individual's specific cancer type and genetic makeup can improve treatment outcomes.
Minimally invasive surgery: Nanomaterials can enable minimally invasive surgical techniques. Nanorobots or nanocapsules can be designed to perform precise procedures, such as tumor resection or drug delivery, with minimal damage to surrounding tissue.
While nanomaterials hold potential in cancer treatment, there are also challenges related to their safety, potential toxicity, and regulatory considerations. Extensive research and rigorous testing are required to ensure the efficacy and safety of these materials in clinical applications. The field of nanomedicine continues to evolve and holds potential for improving cancer diagnosis and treatment.
References
Cancer
Experimental cancer treatments | Nanomaterials and cancer | [
"Materials_science"
] | 696 | [
"Nanomedicine",
"Nanotechnology",
"Nanomaterials"
] |
74,847,146 | https://en.wikipedia.org/wiki/Urea%20adducts | Urea can crystallise with other compounds. These can be called urea adducts or if a solvent is involved, a urea solvate, and the process is called urea extraction crystallization. Urea can also be a neutral ligand if it is coordinated to a central metal atom. Urea can form hydrogen bonds to other oxygen and nitrogen atoms in the substance it crystallises with. This stiffens the solid and raises the melting point. T
List
References
Ureas | Urea adducts | [
"Chemistry"
] | 101 | [
"Organic compounds",
"Ureas"
] |
74,847,951 | https://en.wikipedia.org/wiki/Design%20of%20Royal%20Space%20Force%3A%20The%20Wings%20of%20Honn%C3%AAamise | Gainax's 1987 debut work Royal Space Force: The Wings of Honnêamise has been particularly noted for its design work; during a 2021 interview with the New York Times, science fiction author Ted Chiang, whose Nebula Award-winning "Story of Your Life" was the basis for the Denis Villeneuve movie Arrival, cited Royal Space Force as the single most impressive example of worldbuilding in book or film. Chiang remarked on details such as the film's distinct depiction of money, television, and newspapers: "I just really was impressed by the way that the animators for that film, they invented an entirely new physical culture for this movie. The movie is not about those things, but they really fleshed out this alternate world just as the backdrop for the story that they wanted to tell."
Although Royal Space Force had been green-lit based in large part on the content of a short 1985 "pilot film" version depicting a summary of the story's plot events, writer and director Hiroyuki Yamaga decided afterwards to "destroy" the work the pilot film represented and start over when making the full-length feature film version, in pursuit of a different kind of worldbuilding and character design. This process, described variously as having taken from a year to as much as two years, involved as many as 20 design staff, including art students from outside the anime industry working on the film part-time. This re-design extended beyond the objects depicted in the film to its characters as well, with Yoshiyuki Sadamoto, later to become known for his character designs on the popular anime Nadia: The Secret of Blue Water, Neon Genesis Evangelion, and FLCL designing for Royal Space Force main characters who were recognized at the time as having an atypical look for anime protagonists.
Shinji Higuchi, who in 2017 would share the Director of the Year award with Hideaki Anno for Shin Godzilla at the Japan Academy Film Prize ceremony reflected on both the problems and the personal influence on his career of Royal Space Force design process, which he coordinated as an assistant director on the film. Higuchi recalled the work as having been done in a "horribly inefficient" manner, where far more production time was spent on designing tableware than on animating the climactic rocket launch, yet he regarded the experience as having left him with the "vital asset" of thinking that any obstacles to a production could be overcome through continuing to move ever forward with passion, a philosophy he remarked that he still believed in as a creator.
Design
Starting over from the pilot film
In December 1984, Gainax had set up their first studio as a newly incorporated company in the Takadanobaba neighborhood of Shinjuku to produce a short "pilot film" version of Royal Space Force, with the aim of convincing Bandai to support the making the project as a full-length feature film. After the successful presentation of the pilot film to Bandai in April 1985, Gainax moved their operations to another location in Takadanobaba that offered twice the space of their previous studio, where the existing staff gathered in friends and acquaintances to help visualize the setting of Royal Space Force. Among those joining the crew at this time were two of the film's most prolific world designers: Takashi Watabe, whose designs would include the train station, rocket factory, and Royal Space Force lecture hall and Yoichi Takizawa, whose contributions included the rocket launch gantry, space capsule simulator, and rocket engine test facility.
Yamaga decided that the imagery of the alternate world depicted in the pilot film did not have the kind of different realism he was hoping to achieve in the feature film version. Rather than use the design work of the pilot as a foundation for the full-length anime, it was decided to "destroy" the world of the pilot film and start over again, creating a new series of "image board" paintings to visualize the look of Royal Space Force. The total worldbuilding process went on for roughly a year, and was described as a converse process between Yamaga and the gradually assembled team of designers; expressing his ideas into concrete terms, but also bringing their concrete skills to bear toward the expression of abstract ideas. Yamaga reflected in 2007 that this reciprocal process influenced his writing on the film: "My style is not 'I have a story I created, so you help me make it.' Creators come first, and this is a story I created thinking what story those creators would shine at the most."
Character design
In the decade following Royal Space Force, the Sadamoto-designed Nadia La Arwall and Rei Ayanami would each twice win the Anime Grand Prix fan poll for favorite female character; Sadamoto's Shinji Ikari would also win twice for favorite male character. By contrast, his male and female leads designed for Royal Space Force, Shirotsugh and Riquinni, ranked ninth and twentieth respectively for their categories in the Grand Prix poll of 1987 releases. In a roundtable discussion on Royal Space Force following its release, it was pointed out that neither Shirotsugh nor Riquinni look like typical anime lead characters. Yamaga remarked in his 2007 retrospective that, "One of the changes you can easily see from the pilot version is the character modeling of the protagonist. He used to look like a boy, but has become like a middle-aged man. As you can see in Evangelion later on, characters that Yoshiyuki Sadamoto creates are more attractive when they look young. But of course, he's really skilled, so even if he challenges the area that's not his specialty, he can give us what we're asking for."
Sadamoto in fact did use for the final version of Shirotsugh a model reference significantly older than the 21-year old character's age, the American actor Treat Williams, although the character designer remarked that Yamaga's instructions to make the face square and the eyebrows thicker had him thinking the redesign would look like the director himself. As a reference for Manna, Yamaga referred Sadamoto to actress Tatum O'Neal as she appeared in the first half of the film Paper Moon. Takami Akai remarked that "Sadamoto drew Manna so perfectly that we were sort of intimidated," adding she was "a sidekick who brought out the darker aspects" of Riquinni. Regarding Riquinni herself, Sadamoto commented in 1987 that there seemed to be a model for her, but Yamaga did not tell him who it was. In a 2018 interview session with Niigata University, Yamaga remarked, "What I see now is surprisingly the character Riquinni is nothing but me. At any rate, Shirotsugh is not me. If you ask me where I would position myself in the film, I would identify myself as Riquinni in many aspects, in terms of the way I think. I was probably someone weird [and] religious, ever since my childhood." The appearance of several minor characters in Royal Space Force was based on Gainax staff members or crew on the film, including Nekkerout (Takeshi Sawamura), the Republic aide who plans Shirotsugh's assassination (Fumio Iida), and the director who suggests what Shiro should say before he walks out of his TV interview (Hiroyuki Kitakubo).
Commenting on the character designs in Royal Space Force, Sadamoto remarked that in truth they more reflected the tastes of Gainax than his own personal ones, although at the same time, as the artist, his taste must be reflected in them somehow. Sadamoto discussed the issue in terms of anime character design versus manga character design: "Manga can afford such strong and weird characters, but it's difficult to make good moving characters out of them in anime. The moment I draw a character, for example, you can see how it is going to behave, really ... but I was asking myself what I should be doing. 'Should I make their facial expressions more like those you see in a typical anime?' and so on. I feel that the audience reaction was pretty good, or at least that I managed to get a passing grade."
Design process and philosophy
On the premise that the real world itself was a product of mixed design, Yamaga believed that the sense of alternate reality in Royal Space Force would be strengthened by inviting as many designers as possible to participate in the anime. By September, the worldbuilding of Royal Space Force proceeded forward by a system where designers were free to draw and submit visual concepts based on their interpretation of Yamaga's script; the concept art would then be discussed at a daily liaison meeting between Yamaga and the other staff. Yamaga used "keywords" given to the designers as a starting point for the film's world building; the words were divided into what he termed "symbolic" and "non-symbolic" categories. The director sought to avoid "symbolic" premises where possible; as an example of the difference, Yamaga stated that a "symbolic" way to describe a "cup" would be to call it a "cylindrical object", whereas he preferred the designers start from "non-symbolic" terms that described a cup's function or sensory impressions from use, such as "it holds water," or "it’s cold and sweats when filled with water." Yamaga expressed a concern, however, that relying entirely on this "non-symbolic" approach would have risked making the designs into "abstract paintings," and so decided to retain a certain degree of "symbolic" information in the keywords.
Assistant director Shinji Higuchi had overall responsibility for coordinating the design work with Yamaga's intentions through overseeing the output of its multiple designers. Higuchi gave the example of spoons to describe the design process: he would converse with a group of art students doing part-time design work on the film and consider the shape of the human mouth, the material of the spoon, the structure of its handle, and so forth. Higuchi joked that in this way they spent two months on designing Riquinni's tableware and had only one week to animate the rocket launch, yet those were the priorities. He described the time management on the film as a "mess" and the work as "horribly inefficient" with a sense that there was no end in sight to their endeavors, and yet Higuchi considered the experience to have left him with a "vital asset" as an artist, giving him the "passion to break down all the obstacles that stand in the way of creating something...It's beautiful to have the attitude of 'just keep moving forward'...Maybe there's a smarter way of doing things, but in my case, because I first experienced Royal Space Force: The Wings of Honnêamise, I can't go back."
Higuchi noted moreover that the film's main mecha were designed in a collaborative fashion, citing as an example the Honnêamise air force plane, for which Sadamoto first created a rough sketch, then Takizawa finished up its shape, with its final touches added by Anno. Although his aim was to give a unified look to the kingdom of Honnêamise as the film's main setting, Higuchi also attempted to take care to make it neither too integrated nor too disjointed, remarking that just as the present day world is made from a mixing of different cultures, this would have also been true of a past environment such as the alternate 1950s world of Honnêamise. Yamaga commented that the film also portrayed the idea that different levels of technology are present in a world at the same time depending upon particular paths of development, such as the color TV in use by the Republic, or the air combat between jet and prop planes at the end, which Yamaga compared to similar engagements during the Korean War.
A deliberate exception to Royal Space Force general design approach was the rocket itself, which was adapted from a real-world Soviet model. This exception was later noticed by Hayao Miyazaki, for whom it formed one of his two criticisms of the anime; he was surprised that a film which had gone so far as to change the shape of money did not make the rocket more unusual. Yamaga argued that although the anime reaches its eventual conclusion through a process of different design paths, it was necessary to end the film with a rocket inspired by reality, lest the audience see it as a story about a different world that has nothing to do with them. In their roundtable discussion with OUT, Yamaga described the rocket as also emblematic of the film's approach to mecha; despite its many mecha designs, they all play supporting roles, and even the rocket is not treated as a "lead character".
Notes
Citations
References
Design
Royal Space Force: The Wings of Honnêamise | Design of Royal Space Force: The Wings of Honnêamise | [
"Engineering"
] | 2,667 | [
"Design"
] |
74,848,733 | https://en.wikipedia.org/wiki/Meitei%20astronomy | The astronomy of Meitei civilisation deals with celestial objects, space, and the physical universe as a whole.
Meitei language term “Khenchanglon” () is derived from its ancient Meitei equivalent “Khenchonglon” (), literally meaning "the growing up, evolving or emergence of natural / celestial body(ies) and energy(ies)" and colloquially meaning "astronomy or astronomical bodies, like stars, constellations, planets, satellites, comets, meteors, etc." The Meitei astronomy was also related to the tradition of astrology.
Constellations
Planets
Star tracks
See also
Khongjomnubi Nonggarol
Meitei calendar
Chinese astronomy
Islamic astronomy
Greek astronomy
References
External links
Meitei culture
Astronomy | Meitei astronomy | [
"Astronomy"
] | 159 | [
"nan"
] |
74,848,988 | https://en.wikipedia.org/wiki/MA-FRA | MA-FRA is an Italian chemical company specializing in automotive, motorcycle, boat, and industry care and cleaning products and is one of oldest in the industry.
History
MA-FRA was founded in 1965 by Gianfranco Mattioli during the Economic Boom of the 1960s in Bresso, Italy.
The company collaborated with Nelson Piquet in F1 during the 1980s and with Peugeot Rally in the 1990s. Later, MA-FRA became involved in Ferrari Challenge and collaborated closely with the Mille Miglia.
In 2001, MA-FRA's headquarters moved to the plant in Baranzate, which is still the company's headquarters on the outskirts of Milan.
In the 2010-2020 decade, MAFRA produced the "Ecolabel" line with totally "green" formulations made with natural and biodegradable surfactants.
MA-FRA established the "Detailing School" in 2016 to technically train new professionals dedicated to car detailing. The #Labocosmetica brand was launched in the same year, a line of products specifically for car detailing professionals.
During COVID-19, MA-FRA launched a series of products for car and room sanitization to counter the spread of the pandemic.
In 2022, MA-FRA was represented as a sponsor at numerous automotive events: Autopromotec 2022, the international aftermarket exhibition in Bologna.
The company was announced to participate in the Car Wash Show Europe 2023, the industry's largest event.
References
Companies of Italy
Chemical companies | MA-FRA | [
"Chemistry"
] | 308 | [
"Chemical companies"
] |
74,849,495 | https://en.wikipedia.org/wiki/Agglutinogen | Agglutinogen is an antigen that causes the formation of agglutinins in the body and leads to agglutination, such as hemagglutination, which involves red blood cells (RBCs).
The kind of agglutinogens present on the red blood cells helps determine the blood type of a person.
For example, in the ABO blood type classification system, if a person has blood type A, then the red blood cells exhibit agglutinogens A or antigens A. If the blood is of type B, the agglutinogens present are of type B. If the blood is of type AB, then both agglutinogens A and B are present. In blood type O, there are no agglutinogens on the surface of the red blood cells. The agglutinogens are made by specific enzymes, which are encoded in genes. Different versions, or alleles give rise to different agglutinogens: the A allele codes for an enzyme that makes the agglutinogen A and similarly the B allele results in the agglutinogen B. A third version of this gene, the O allele, codes for a protein that is not functional; it makes no surface molecules at all.
Everyone inherits two alleles of the gene, one from each parent. The combination of the two alleles determines the blood type.
The existence of agglutinogens on the surface of red blood cells has been inferred from the reactions, hemolysis and agglutination, which occur on contact with specific antisera.
References
Antigens | Agglutinogen | [
"Chemistry"
] | 341 | [
"Antigens",
"Biomolecules"
] |
74,849,743 | https://en.wikipedia.org/wiki/Sociedad%20Espa%C3%B1ola%20para%20el%20Procesamiento%20del%20Lenguaje%20Natural | Sociedad Española para el Procesamiento del Lenguaje Natural (SEPLN, in English: Spanish association for Natural Language Processing) is a scientific and professional organization for researching natural language processing. Its namesake conference has been held each summer since 1983 in Spanish locations where computational linguistics research is carried out.
It was founded in 1983, and its purpose is to promote and divulge every kind of activity related to teaching, research and development in the natural language processing field, on both a national and international level.
The first SEPLN president was Felisa Verdejo, when she was a professor at the University of the Basque Country in San Sebastián.
Activities
Among the main activities of the SEPLN are the organization of an annual congress, which is attended by the research groups working in the natural language processing field, especially for Spanish, Catalan, Basque or Galician languages; the edition of the academic journal Procesamiento del Lenguaje Natural supported by a committee who guarantee some established criteria of quality and periodicity; a web server with information about issues related to natural language processing and an email service which inform about the current issues and is used as an open forum.
The journal is published every six months, so two issues per year are published (March and September) with the last advances in NLP.
The Journal has the quality seal of the Spanish Foundation for Science and Technology (FECYT), which certifies it as a magazine of excellence, and therefore included in the Spanish Scientific Journals Repository (RECyT, Spanish Repository of Science and technology). The Journal received the seal of quality (ISO9001) in 2012, from the Spanish Federation of Science and Technology (FECYT). The Journal was indexed in the Emerging Sources Citation Index (ESCI) in 2016. The ESCI is the new edition of Web of Science, and Thonson Reuters is assessing the quality of the journals of ESCI in order to add those ones with a 'high scientific quality' in the Science Citation Index Expanded, Social Sciences Citation Index, and Arts & Humanities Citation Index.
NLP community
The SEPLN society has built an academic community around natural language processing, coordinating more than thirty research groups working especially with any of these four languages: Spanish, Basque, Catalan and Galician. This community is a reference in Latin America and worldwide, especially because it has created models for the successful processing of Spanish and three minority languages.
The coordinated development of technology for Spanish, Basque, Catalan and Galician by this community has benefited the four languages as a whole. The Asturian and Aragonese languages have also been studied. This positive influence of SEPLN's activity can be seen in the ELE report that analysed the situation of European languages in language technology by 2022. Spanish was one of the four best resourced among the official languages, behind English, on a par with German and French; Catalan, Basque and Galician were the best placed among the non-official languages, along with Welsh, and were in a better position than some of the official or national languages (better than Irish Gaelic and Maltese).
Locations
This is the timeline of cities with a NLP group that organized SEPLN conferences:
Presidents
The presidents who have governed this society since its creation have been the following:
See also
Association for Computational Linguistics
References
External links
@SEPLN SEPLN Twitter account
PLN journal (official website)
Collection of SEPLN historical photographs
Computational linguistics
International professional associations
Organizations established in 1983
Computer science-related professional associations | Sociedad Española para el Procesamiento del Lenguaje Natural | [
"Technology"
] | 710 | [
"Natural language and computing",
"Computational linguistics"
] |
74,850,183 | https://en.wikipedia.org/wiki/Minimum-cost%20spanning%20tree%20game | A minimum-cost spanning-tree game (MCST game) is a kind of a cooperative game. In an MCST game, each player is a node in a complete graph. The graph contains an additional node - the supply node - denoted by s. The goal of the players is that all of them will be connected by a path to s. To this end, they need to construct a spanning tree. Each edge in the graph has a cost, and the players build the minimum cost spanning tree. The question then arises, how to allocate the cost of this MCST among the players?
The solution offered by cooperative game theory is to consider the cost of each potential coalition - each subset of the players. The cost of each coalition S is the minimum cost of a spanning tree connecting only the nodes in S to the supply node s. The value of S is minus the cost of S. Using these definitions, various solution concepts from cooperative game theory can be applied. MCST games were introduced by Bird in 1976.
Properties
The core of every MCST game is non-empty.
The nucleolus is the unique point in the intersection of the core and the kernel.
If the underlying network is a tree, then the nucleolus coincides with the kernel.
Computation
One solution in the core can be read directly from any minimum cost spanning tree graph associated with the problem.
There is an algorithm that requires O(n2) elementary operations for computing each additional point in the core.
In general MCST games, computing the nucleolus is NP-hard; the proof is by reduction from the minimum set cover problem. There is an algorithm that computes the nucleolus in time O(n3|B|), where B is the set of relevant coalitions (in general, |B|=2n, but in some special cases, only a subset of the coalitions are relevant).
If the underlying network is a tree, then the nucleolus can be computed in O(n3) time, and the Shapley value can be computed in O(n) time. The run-time of computing the nucleolus can be reduced to O(n log n) using efficiently mergeable heaps. In particular cases, the nucleolus can be computed in O(n) time.
Spanning forest games
A minimum-cost spanning-forest game (MCSF game) is a generalization of an MCST game, in which multiple supply-nodes are allowed. In general, the core of an MCSF game may be empty. However, if the underlying network is a tree, the core is always non-empty, and core points can be computed in strongly-polynomial time.
References
Cooperative games
Spanning tree | Minimum-cost spanning tree game | [
"Mathematics"
] | 566 | [
"Game theory",
"Cooperative games"
] |
74,850,217 | https://en.wikipedia.org/wiki/Collective%E2%80%93amoeboid%20transition | The collective–amoeboid transition (CMT) is a process by which collective multicellular groups dissociate into amoeboid single cells following the down-regulation of integrins. CMTs contrast with epithelial–mesenchymal transitions (EMT) which occur following a loss of E-cadherin. Like EMTs, CATs are involved in the invasion of tumor cells into surrounding tissues, with amoeboid movement more likely to occur in soft extracellular matrix (ECM) and mesenchymal movement in stiff ECM. Although once differentiated, cells typically do not change their migration mode, EMTs and CMTs are highly plastic with cells capable of interconverting between them depending on intracelluar regulatory signals and the surrounding ECM.
CATs are the least common transition type in invading tumor cells, although they are noted in melanoma explants.
See also
Collective cell migration
Dedifferentiation
Invasion (cancer)
References
Animal developmental biology
Cancer research
Cell movement
Cellular processes
Tissue engineering | Collective–amoeboid transition | [
"Chemistry",
"Engineering",
"Biology"
] | 216 | [
"Biological engineering",
"Cloning",
"Chemical engineering",
"Tissue engineering",
"Cellular processes",
"Medical technology"
] |
74,850,229 | https://en.wikipedia.org/wiki/National%20Messaging%20System | The National Messaging System (NMS) is an upcoming Australian cell broadcast emergency population warning system that is slated to replace the current location-targeted, SMS-based Emergency Alert system. It is currently expected to be in operation by late 2024.
History
The existing Emergency Alert Australia system, established in 2009, is a location-based SMS (LB-SMS) system and can also call landlines with automated alerts. The system was used in the 2019-20 Black Summer Bushfires, with 492,938 landline calls and 4,194,576 text messages sent to residents in affected areas.
The Royal Commission into National Natural Disaster Arrangements in 2020 found that emergency warning systems were effective tools for governments to use to alert citizens of threats. However, it found that limitations with Emergency Alert meant it was unable to reach everyone facing an "emerging or imminent threat", and that the underlying LB-SMS technology was considered outdated.
For landlines, automated audio alerts failed to be delivered when:
the landline telephone was in use when the alert was issued (i.e., engaged)
the landline telephone was not answered
there was a power outage and a cordless telephone was being used
the landline telephone was outside the warning area but still in an at-risk location
the landline telephone was not registered under the correct address.
Text messages failed to be delivered when:
individuals' message inboxes were full
the mobile phone was switched off or outside of a mobile coverage area
the last known location of the mobile phone was outside the defined warning area when the alert was issued but still at risk
individuals had not updated their address
the mobile phone had moved into a warning area after the alert had been issued and sent to devices
the mobile phone was in a mobile coverage blackspot.
The commission also found that the state-based nature of Emergency Alert meant that it was possible for residents living near a state's border to receive an emergency alert sent by the system from the other state, as those residents' landlines may be connected to the network of the other state. For instance, New South Wales border residents could receive an alert issued by Queensland authorities because their proximity to Queensland meant that they were connected to the telephone network in Queensland.
It was found that a review of new and emerging telephony technologies for use beyond 2023–24 to improve the issuing of emergency alerts nationwide, including for those with a disability and/or are culturally/linguistically diverse had been commissioned by the Department of Home Affairs through Emergency Management Australia. The Commission recommended that the review, funding and upgrade of Emergency Alert be considered a priority to ensure it used the best available technology to improve the way warnings are issued, and to better cater to those with a disability and culturally and linguistically diverse communities.
After receiving $2.2 million in funding from the 2021 budget, in August 2021, the Australian Government issued a tender for proposals from suppliers for a cell broadcast-based emergency warning system, with implementation slated for January 2022, and a three-year contract starting the same year.
Features
The NMS will utilise cell broadcast technology, which allows messages to be broadcast directly from a radio cell tower to all devices in the vicinity, rather than disseminating alerts through text messages to devices in a specified location as with the current Emergency Alert system. The National Emergency Management Agency (NEMA) says the technology will allow for "near real-time", simultaneous messaging to all devices in a specified area and is unconstrained by telecommunications network congestion, a problem which arose with the current system. Messages would have a character limit of 1395 characters, and would be able to have a priority level specified that would differentiate the way messages are displayed on receiving devices.
Devices receiving alerts under the new system would display an on-screen message that cannot be easily dismissed. The technology would allow for multilingual messaging, but it is not clear yet how this functionality would be utilised by the NMS and what languages messages would be offered in. Location targeting under the new system would allow an area as small as a one-kilometre radius to be defined, and would also enable messages to be sent to individual local government areas (LGAs).
References
Emergency communication
Emergency management in Australia
Emergency population warning systems | National Messaging System | [
"Technology"
] | 867 | [
"Warning systems",
"Emergency population warning systems"
] |
69,083,621 | https://en.wikipedia.org/wiki/Ascorbyl%20glucoside | Ascorbyl glucoside (AA-2G) is an ascorbic acid derivative that contains at least one glycosyl group. Ascorbyl glucoside is commonly used in cosmetic products to administer vitamin C topically. Ascorbyl glucoside exhibits superior stability and penetration ability compared to ascorbyl phosphate salts, but the rate of its in vivo conversion to ascorbic acid is not known. Ascorbyl glucosides such as AA-2G, like many other derivatives of the ascorbic acid, show antiscorbutic effects. It is also sometimes used in skin whitening products.
Ascorbyl glucoside is synthesized through a glycosylation process catalyzed by glycosyltransferase-class enzymes.
See also
Ascorbyl palmitate
References
Vitamin C
Glucosides
Cosmetics chemicals | Ascorbyl glucoside | [
"Chemistry"
] | 191 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
69,084,310 | https://en.wikipedia.org/wiki/Joint%20European%20Disruptive%20Initiative | The Joint European Disruptive Initiative (JEDI) is a European funding agency aiming at promoting disruptive technologies. It funds innovation in different "missions" (environment and energy, healthcare, education, digital, space, and oceans), with the goal of bringing "Europe in a leadership position in breakthrough technologies". It organizes scientific competitions focused on disruptive technologies. JEDI also makes policy recommendations to strengthen European technology sovereignty. , JEDI was funding the projects of over 6,000 researchers in 29 countries across Europe and the world. It is operated independently from any European governments with funding from foundations, companies, individuals and public institutions.
JEDI was inspired by DARPA (Defense Advanced Research Projects Agency), the technology research and development agency of the United States Department of Defense. JEDI calls itself a "precursor" to a European advanced research projects agency.
Research on Covid-19
The Joint European Disruptive Initiative launched its first "Darpa-type GrandChallenge" on Covid-19 on May 5, 2020. The competition consisted in screening "billions of molecules with blocking interactions on SARS-CoV-2" to develop a drug against the coronavirus — with each participant having to use at least three different calculation methods for the simulations. The foundation claims to have had approximately 54 billions of molecules screened and 878 of them being synthesized. A paper published in Nature showed that the protein PDB 6W9C was one of the most used in silico drug design against Covid-19.
References
Research councils
Science and technology in Europe
Grants (money)
Life sciences industry
Research projects | Joint European Disruptive Initiative | [
"Biology"
] | 321 | [
"Life sciences industry"
] |
69,085,407 | https://en.wikipedia.org/wiki/List%20of%20QWERTY%20keyboard%20language%20variants | There are a large number of QWERTY keyboard layouts used for languages written in the Latin script. Many of these keyboards include some additional symbols of other languages, but there also exist layouts that were designed with the goal to be usable for multiple languages (see Multilingual variants). This list gives general descriptions of QWERTY keyboard variants along with details specific to certain operating systems, with emphasis on Microsoft Windows.
Specific language variants
English
Canada
English-speaking Canadians have traditionally used the same keyboard layout as in the United States, unless they are in a position where they have to write French on a regular basis. French-speaking Canadians respectively have favoured the Canadian French (CFR) and the Canadian French ACNOR (CFA) keyboard layouts (see below).
United Kingdom
The United Kingdom and Ireland use a keyboard layout based on the 48-key version defined in the (now withdrawn) British Standard BS 4822. It is very similar to that of the United States, but has an AltGr key and a larger Enter key, includes £ and € signs and some rarely used EBCDIC symbols (¬, ¦), and uses different positions for the characters @, ", #, ~, \, and |.
The BS 4822:1994 standard did not make any use of the AltGr key and lacked support for any non-ASCII characters other than ¬ and £. It also assigned a key for the non-ASCII character broken bar (¦), but lacks one for the far more commonly used ASCII character vertical bar (|). It also lacked support for various diacritics used in the Welsh alphabet, and the Scottish Gaelic alphabet; and also is missing the letter yogh, ȝ, used very rarely in the Scots language. Therefore, various manufacturers have modified or extended the BS 4822 standard:
The B00 key (left of Z), shifted, results in vertical bar (|) on some systems (e.g. Windows UK/Ireland keyboard layout and Linux/X11 UK/Ireland keyboard layout), rather than the broken bar (¦) assigned by BS 4822 and provided in some systems (e.g. IBM OS/2 UK166 keyboard layout)
The E00 key (left of 1) with AltGr provides either vertical bar (|) (OS/2's UK166 keyboard layout, Linux/X11 UK keyboard layout) or broken bar (¦) (Windows UK/Ireland keyboard layout)
Support for the diacritics needed for Scots Gaelic and Welsh was added to Windows and ChromeOS using a "UK-extended" setting (see below); Linux and X-Windows systems have an explicit or redesignated compose key for this purpose.
UK Apple keyboard
The British version of the Apple Keyboard does not use the standard UK layout. Instead, some older versions have the US layout (see below) with a few differences: the sign is reached by and the sign by , the opposite to the US layout. The is also present and is typed with . Umlauts are reached by typing and then the vowel, and ß is reached by typing .
Newer Apple "British" keyboards use a layout that is relatively unlike either the US or traditional UK keyboard. It uses an elongated return key, a shortened left with and in the newly created position, and in the upper left of the keyboard are and instead of the traditional EBCDIC codes. The middle-row key that fits inside the key has and .
United States
The arrangement of the character input keys and the Shift keys contained in this layout is specified in the US national standard ANSI-INCITS 154-1988 (R1999) (formerly ANSI X3.154-1988 (R1999)), where this layout is called "ASCII keyboard". The complete US keyboard layout, as it is usually found, also contains the usual function keys in accordance with the international standard ISO/IEC 9995-2, although this is not explicitly required by the US American national standard.
US keyboards are used not only in the United States, but also in many other English-speaking jurisdictions (except the UK and Ireland) such as Canada, Australia, the Caribbean nations, Hong Kong, Malaysia, India, Pakistan, Bangladesh, Singapore, New Zealand, and South Africa. Local spelling in these regions sometimes conforms more closely to British English usage, creating the undesirable side effect of also setting the language to US English rather than the local orthography. This conflict would be fixed in Windows 8 and later versions when Microsoft separated the keyboard and language settings. US keyboards also see use in Indonesia and the Philippines, the former of which uses the same 26-letter alphabet as English.
The US keyboard layout has a second Alt key instead of the AltGr key and does not use any dead keys; this makes it inefficient for all but a handful of languages. On the other hand, the US keyboard layout (or the similar UK layout) is occasionally used by programmers in countries where the keys for []{} are located in less convenient positions on the locally customary layout.
On some keyboards the enter key is bigger than traditionally and takes up also a part of the line above, more or less the area of the traditional location of the backslash key (\). In these cases the backslash is located in alternative places. It can be situated one line above the default location, on the right of the equals sign key (=). Sometimes it is placed one line below its traditional situation, on the right of the apostrophe key (') (in these cases the enter key is narrower than usual on the line of its default location). It may also be two lines below its default situation on the right of a narrower than traditionally right shift key. A variant of this layout is used in Arabic-speaking countries.
This variant has the | \ key to the left of Z, ~ ` key where the | \ key is in the usual layout, and the > < key where the ~ ` key is in the usual layout.
Czech
The typewriter came to the Czech-speaking area in the late 19th century, when it was part of Austria-Hungary where German was the dominant language of administration. Therefore, Czech typewriters have the QWERTZ layout.
However, with the introduction of imported computers, especially since the 1990s, the QWERTY keyboard layout is frequently used for computer keyboards. The Czech QWERTY layout differs from QWERTZ in that the characters (e.g. @$& and others) missing from the Czech keyboard are accessible with AltGr on the same keys where they are located on an American keyboard. In Czech QWERTZ keyboards the positions of these characters accessed through AltGr differs.
Danish
Both the Danish and Norwegian keyboards include dedicated keys for the letters Å/å, Æ/æ and Ø/ø, but the placement is a little different, as the and keys are swapped on the Norwegian layout. (The Finnish–Swedish keyboard is also largely similar to the Norwegian layout, but the and are replaced with and . On some systems, the Danish keyboard may allow typing Ö/ö and Ä/ä by holding the or key while striking and , respectively.) Computers with Windows are commonly sold with ÖØÆ and ÄÆØ printed on the two keys, allowing same computer hardware to be sold in Denmark, Finland, Norway and Sweden, with different operating system settings.
Dutch (Netherlands)
Though it is seldom used (most Dutch keyboards use US International layout), the Dutch layout uses QWERTY and adds the € sign, the diaeresis (), the German (), the pilcrow (), the (US) cent sign (), the Greek letter µ (for the micro- sign), the braces ( and the guillemet quotation marks (), as well as having different locations for some other symbols. An older version contained a single-stroke key for the Dutch digraph ij, which is usually typed by the combination of and . In the 1990s, there was a version with the now-obsolete florin sign () for PCs.
See also below.
Estonian
The keyboard layout used in Estonia is virtually the same as the Swedish layout. The main difference is that the and keys (to the right of ) are replaced with and respectively (the latter letter being the most distinguishing feature of the Estonian alphabet). Some special symbols and dead keys are also moved around.
Faroese
The same as the Danish layout with added (Eth), since the Faroe Islands are a self-governed part of the Kingdom of Denmark.
French (Canada)
The Canadian French (CFR) keyboard layout is commonly used in Canada by French-speaking Canadians. It is the most common layout for laptops and stand-alone keyboards aimed at the Francophone market. Unlike the AZERTY layout used in France and Belgium, it is a QWERTY layout and as such is also relatively commonly used by English speakers in the US and Canada (accustomed to using US standard QWERTY keyboards) for easy access to the accented letters found in some French loanwords. It can be used to type all accented French characters, as well as some from other languages, and serves all English functions as well. It is popular mainly because of its close similarity to the basic US keyboard commonly used by English-speaking Canadians and Americans, historical use of US-made typewriters by French-Canadians. The right Alt key is reconfigured as an AltGr key that gives easy access to a further range of characters (marked in blue and red on the keyboard image. Blue indicates an alternative character that will display as typed. Red indicates a dead key: the diacritic will be applied to the next vowel typed.) The traditional Canadian French keyboard from IBM must use an ISO keyboard. The French guillemets located on the extra key are needed to type proper French, they are not optional. A dvorak version (traditional Canadian French layout) is also supported by Microsoft Windows.
In this keyboard, the key names are translated to French:
is or (short for Fixer/Verrouiller Majuscule, meaning Lock Uppercase).
is .
is .
The "hybrid" keyboard layout, often referred incorrectly as "canadian multilingual" or "bilingual" is a mix between the US English and the Canadian French layout over an ISO keyboard. This layout has been developed by manufacturers as a cost saving strategy first for their low end laptops. They tend to be extended to the mid-range laptops in the recent years and sold wrongly as a "French" keyboard. Today, this layout seems to be criticized by both anglophones and francophones. The anglophones accustomed to the ANSI keyboard complain about the small ISO shift on left and francophones can find these legends hard to read and messy. In this keyboard, the key names are translated in both French and English. This keyboard can be netherless useful for programming.
In 1988, the Quebec government has developed a new keyboard layout, using proper keys for ,,,,, standardized by the CSA Group and adopted also by the federal government. This layout is known as Canadian French (Legacy) today on Windows and is considered to be the ancestor to the actual Canadian Multilingual Standard. The CMS on Windows and Linux is based on the CAN/CSA Z243.200-92 standard (launched in 1992 by the CSA Group, revised in 2021). Apple use a layout based mostly on the standardized CSA keyboard from 1992 too, called Canadian French ― CSA. The CMS is one of the few layouts allowing to type the ligature œ/Œ, common in French. The integral version use pictograms based on the ISO 9995-7 standard. Unlike the traditional Canadian French keyboard developed by IBM, the CSA Keyboard is also standardized on both ISO and ANSI keyboard. The French guillemets on the CSA keyboard are located on the level 3 with the and keys. The Ù on the extra key can be replaced by a combinaison of + (dead key left from ) then or +. The ISO version still netherless needed by the Quebec government, following their higher standard named SGQRI-001. The Quebec CSA keyboard is also named Canadian French ACNOR (CFA) or Canadian International Bilingual.
Greek
The stress accents, indicated in red, are produced by pressing that key (or shifted key) followed by an appropriate vowel.
Use of the "AltGr" key may produce the characters shown in blue.
German
Germany, Austria, Switzerland, Liechtenstein, and Luxembourg use QWERTZ layouts, where the letter Z is to the right of T.
Icelandic
The Icelandic keyboard layout is different from the standard QWERTY keyboard because the Icelandic alphabet has some special letters, most of which it shares with the other Nordic countries:
Þ/þ, Ð/ð, Æ/æ, and Ö/ö. (Æ/æ also occurs in Norwegian, Danish and Faroese, Ð/ð in Faroese, and Ö/ö in Swedish, Finnish and Estonian. In Norwegian Ö/ö could be substituted for Ø/Ø which is the same sound/letter and is widely understood).
The letters Á/á, Ý/ý, Ú/ú, Í/í, Ó/ó and É/é are produced by first pressing the dead key and then the corresponding letter. The Nordic letters Å/å and Ä/ä can be produced by first pressing , located below the key, and (for ¨) which also works for the non-Nordic ÿ, Ü/ü, Ï/ï, and Ë/ë. These letters are not used natively in Icelandic, but may have been implemented for ease of communication in other Nordic languages. Additional diacritics may be found behind the key: for ˋ (grave accent) and for ˆ (circumflex).
Irish
Windows includes an Irish layout which supports acute accents with for the Irish language and grave accents with the dead key for Scottish Gaelic. The other Insular Celtic languages have their own layout. The UK or UK-Extended layout is also frequently used.
Italian
Braces (right above square brackets and shown in purple) are given with both AltGr and Shift pressed.
The tilde (~) and backquote (`) characters are not present on the Italian keyboard layout (with Linux, they are available by pressing +, and +; Windows might not recognise these keybindings).
When using Microsoft Windows, the standard Italian keyboard layout does not allow one to write 100% correct Italian language, since it lacks capital accented vowels, and in particular the È key. The common workaround is writing E' (E followed by an apostrophe) instead, or relying on the auto-correction feature of several word processors when available. It is possible to obtain the È symbol in MS Windows by typing + . Mac users, however, can write the correct accented character by pressing + + or, in the usual Mac way, by pressing the correct key for the accent (in this case + ) and subsequently pressing the wanted letter (in this case + ). Linux users can also write it by pressing the key with enabled.
There is an alternate layout, which differs only in disposition of characters accessible through , and includes the tilde and the curly brackets. It is commonly used in IBM keyboards.
Italian typewriters often have the QZERTY layout instead.
The Italian-speaking part of Switzerland uses the QWERTZ keyboard.
Latvian
Although rarely used, a keyboard layout specifically designed for the Latvian language called ŪGJRMV exists. The Latvian QWERTY keyboard layout is most commonly used; its layout is the same as the United States one, but with a dead key, which allows entering special characters (āčēģīķļņōŗšūž). The most common dead key is the apostrophe ('), which is followed by Alt+Gr (Windows default for Latvian layout). Some prefer using the tick (`).
Lithuanian
Where in standard QWERTY the number row is located, you find in Lithuanian QWERTY: Ą, Č, Ę, Ė, Į, Š, Ų, Ū, Ž, instead of their counterparts 1, 2, 3, 4, 5, 6, 7, 8, =. If you still want to use the numbers of the mentioned 'number row', you can create them in combination with the -key. Aside from these changes the keyboard is standard QWERTY. Besides QWERTY, the ĄŽERTY layout without the adjustment of the number row is used.
Maltese
The Maltese language uses Unicode (UTF-8) to display the Maltese diacritics: ċ Ċ; ġ Ġ; ħ Ħ; ż Ż (together with à À; è È; ì Ì; ò Ò; ù Ù). There are two standard keyboard layouts for Maltese, according to "MSA 100:2002 Maltese Keyboard Standard"; one of 47 keys and one of 48 keys. The 48-key layout is the most popular.
Norwegian
The Norwegian languages use the same letters as Danish, but the Norwegian keyboard differs from the Danish layout regarding the placement of the , and (backslash) keys. On the Danish keyboard, the and are swapped. The Swedish keyboard is also similar to the Norwegian layout, but and are replaced with and . On some systems, the Norwegian keyboard may allow typing Ö/ö and Ä/ä by holding the or key while striking and , respectively.
There is also an alternative keyboard layout called Norwegian with Sámi, which allows for easier input of the characters required to write various Sámi languages. All the Sámi characters are accessed through the key.
On Macintosh computers, the Norwegian and Norwegian extended keyboard layouts have a slightly different placement for some of the symbols obtained with the help of the or keys. Notably, the $ sign is accessed with and ¢ with . Furthermore, the frequently used @ is placed between and .
Polish
Most typewriters use a QWERTZ keyboard with Polish letters (with diacritical marks) accessed directly (officially approved as "Typist's keyboard", , Polish Standard PN-87), which is mainly ignored in Poland as impractical (custom-made keyboards, e.g., those in the public sector as well as some Apple computers, present an exception to this paradigm); the "Polish programmer's" () layout has become the de facto standard, used on virtually all computers sold on the Polish market.
Most computer keyboards in Poland are laid out according to the standard US visual and functional layout. Polish diacritics are accessed by using the AltGr key with a corresponding similar letter from the base Latin alphabet. Normal capitalization rules apply with respect to Shift and Caps Lock keys. For example, to enter "Ź", one can type Shift+AltGr+X with Caps Lock off, or turn on Caps Lock and type AltGr+X.
Both ANSI and ISO mechanical layouts are common sights, and even some non-standard mechanical layouts are in use. ANSI is often preferred, as the additional key provides no additional function, at least in Microsoft Windows where it duplicates the backslash key, while taking space from the Shift key. Many keyboards do not label AltGr as such, leaving the Alt marking as in the US layout – the right Alt key nevertheless functions as AltGr in this layout, causing possible confusion when keyboard shortcuts with the Alt key are required (these usually work only with the left Alt) and causing the key to be commonly referred to as right Alt (). However, keyboards with AltGr marking are available and it is also officially used by Microsoft when depicting the layout.
Also, on MS Windows, the tilde character "~" (Shift+`) acts as a dead key to type Polish letters (with diacritical marks) thus, to obtain an "Ł", one may press Shift+` followed by L. The tilde character is obtained with (Shift+`) then space.
In Linux-based systems, the euro symbol is typically mapped to Alt+5 instead of Alt+U, the tilde acts as a normal key, and several accented letters from other European languages are accessible through combinations with left Alt. Polish letters are also accessible by using the compose key.
Software keyboards on touchscreen devices usually make the Polish diacritics available as one of the alternatives which show up after long-pressing the corresponding Latin letter. However, modern predictive text and autocorrection algorithms largely mitigate the need to type them directly on such devices.
There is also another expanded Polish keyboard layout since 2021, based on the layout from Polish 80s computers Mazovia and wide expanded into all Latin diacritical signs, Greek signs, mathematical signs, IPA signs, typographical signs, symbols and sign "zł" meaning Polish currency, available in two versions, QWERTZ and QWERTY.
Portuguese
Brazil
The Brazilian computer keyboard layout is specified in the ABNT NBR 10346 variant 2 (alphanumeric portion) and 10347 (numeric portion) standards.
Essentially, the Brazilian keyboard contains dead keys for five variants of diacritics in use in the language; the letter Ç, the only application of the cedilha in Portuguese, has its own key. In some keyboard layouts the + combination produces the ₢ character (Unicode 0x20A2), symbol for the old currency cruzeiro, a symbol that is not used in practice (the common abbreviation in the eighties and nineties used to be Cr$). The cent sign ¢, is accessible via +, but is not commonly used for the centavo, subunit of previous currencies as well as the current real, which itself is represented by R$. The Euro sign € is not standardized in this layout. The masculine and feminine ordinals ª and º are accessible via combinations. The section sign § (Unicode U+00A7), in Portuguese called parágrafo, is nowadays practically only used to denote sections of laws.
Variant 2 of the Brazilian keyboard, the only which gained general acceptance (MS Windows treats both variants as the same layout), has a unique mechanical layout, combining some features of the ISO 9995-3 and the JIS keyboards in order to fit 12 keys between the left and right Shift (compared to the American standard of 10 and the international of 11). Its modern, IBM PS/2-based variations, are thus known as 107-keys keyboards, and the original PS/2 variation was 104-key. Variant 1, never widely adopted, was based on the ISO 9995-2 keyboards. To make this layout usable with keyboards with only 11 keys in the last row, the rightmost key (/?°) has its functions replicated across the +, +, and + combinations.
Portugal
Essentially, the Portuguese keyboard contains dead keys for five variants of diacritics; the letter Ç, the only application of the cedilha in Portuguese, has its own key, but there is also a dedicated key for the ordinal indicators and a dedicated key for quotation marks. The + combination for producing the euro sign € (Unicode 0x20AC) has become standard. On some QWERTY keyboards the key labels are translated, but the majority are labelled in English.
During the 20th century, a different keyboard layout, HCESAR, was in widespread use in Portugal.
Romanian
The current Romanian National Standard SR 13392:2004 establishes two layouts for Romanian keyboards: a "primary" one and a "secondary" one.
The "primary" layout is intended for traditional users who have learned how to type with older, Microsoft-style implementations of the Romanian keyboard. The "secondary" layout is mainly used by programmers as it does not contradict the physical arrangement of keys on a US-style keyboard. The "secondary" arrangement is used as the default Romanian layout by Linux distributions, as defined in the "X Keyboard Configuration Database".
There are four Romanian-specific characters that are incorrectly implemented in versions of Microsoft Windows before Vista:
Ș (U+0218, S with comma), incorrectly implemented as Ş (U+015E, S with cedilla)
ș (U+0219, s with comma), incorrectly implemented as ş (U+015F, s with cedilla)
Ț (U+021A, T with comma), incorrectly implemented as Ţ (U+0162, T with cedilla)
ț (U+021B, t with comma), incorrectly implemented as ţ (U+0163, t with cedilla)
The cedilla-versions of the characters do not exist in the Romanian language (they came to be used due to a historic bug). The UCS now says that encoding this was a mistake because it messed up Romanian data and the letters with cedilla and the letters with comma are the same letter with a different style.
Since Romanian hardware keyboards are not widely available, Cristian Secară has created a driver that allows Romanian characters to be generated with a US-style keyboard in all versions of Windows prior to Vista through the use of the AltGr key modifier.
Windows Vista and newer versions include the correct diacritical signs in the default Romanian Keyboard layout.
This layout has the Z and Y keys mapped like in English layouts and also includes characters like the 'at' (@) and dollar ($) signs, among others. The older cedilla-version layout is still included albeit as the 'Legacy' layout.
Slovak
In Slovakia, similarly to the Czech Republic, both QWERTZ and QWERTY keyboard layouts are used. QWERTZ is the default keyboard layout for Slovak in Microsoft Windows.
Spanish
Spain
The Spanish keyboard layout is used to write in Spanish and in other languages of Spain such as Catalan, Basque, Galician, Aragonese, Asturian and Occitan. It includes Ñ for Spanish, Asturian and Galician, the acute accent, the diaeresis, the inverted question and exclamation marks (¿, ¡), the superscripted o and a (º, ª) for writing abbreviated ordinal numbers in masculine and feminine in Spanish and Galician, and finally, some characters required only for typing Catalan and Occitan, namely Ç, the grave accent and the interpunct ( / , used in l·l; located at Shift-3). It can also be used to write other international characters, such as those using a circumflex accent (used in French and Portuguese among others), which are available as dead keys. However, it lacks two characters used in Asturian: Ḥ and Ḷ (historically, general support for these two has been poor – they are not present in the ISO 8859-1 character encoding standard, or any other ISO/IEC 8859 standard). Several alternative distributions, based on this one or created from scratch, have been created to address this issue (see the Other original layouts and layout design software section for more information).
On most keyboards, € is marked as Alt Gr + E and not Alt Gr + 5 as shown in the image. However, in some keyboards, € is found marked twice.
Spanish keyboards are usually labelled in Spanish instead of English, its abbreviations being:
On some keyboards, the c-cedilla key (Ç) is located one or two lines above, rather than on the right of, the acute accent key (´). In some cases it is placed on the right of the plus sign key (+), while in other keyboards it is situated on the right of the inverted exclamation mark key (¡).
Latin America, officially known as Spanish Latinamerican sort
The Latin American Spanish keyboard layout is used throughout Mexico, Central and South America. Before its design, Latin American vendors had been selling the Spanish (Spain) layout as default; this is still being the case, with both keyboard layouts being sold simultaneously all over the region.
Its most obvious difference from the Spanish (Spain) layout is the lack of a Ç key. While it has the tilde (~), it is not a dead key on Windows (available on Linux as an option to be enabled). It also has the circunflex (^) and the grave accent (`) available as tertiary position characters on and while in the Spanish Spain layout the grave has its own key and the diaeresis can be typed using as a secondary position character. This is not a problem when writing in Spanish but it generates issues when trying to type in other languages such as French or Portuguese, due to the inhability to produce the Ç or the unfavourable position of the other dead keys. This is specially true either for countries with large commercial ties to Brazil (Argentina, Paraguay and Uruguay) or for language learners and translators. Apart from that, the € sign is nonexistent on this layout. It has to be typed from the numeric pad using an altcode or copied and pasted from other websites.
The Latin American layout, although similar to the Spanish Spain layout, has some peculiarities: the is placed next to the , while in the Spanish Spain layout it is located next to the . Meanwhile, the @ sign (done by pressing in the Spain layout) is instead produced by pressing . These two features generate a lot of confusion on many users as many machines use a different keyboard layout that the one set as default on the system: one may encounter a computer with the Spanish Spain layout set up as default but also having the Latin American keyboard physically, or the other way around. Thus, it is very common for people to hit the wrong dead key or be unable to produce a character as shown on the layout because these two keyboards are available side by side to the public, so users generally struggle from the transition of i.e. using the Latin American distribution at home while employing the Spanish Spain layout at work or school or viceversa.
In this layout, key names are translated: "Caps Lock" is rendered as "Bloq Mayús", "Enter" appears as either "Intro" or "Entrar" depending on the vendor, "Page up" and "page down" appear as "re pág" and "av pag", respectively; "shift" is translated as "mayús", and "backspace" is "retroceso".
Swedish
The central characteristics of the Swedish keyboard are the three additional letters Å/å, Ä/ä, and Ö/ö. The same visual layout is also in use in Finland and Estonia, as the letters Ä/ä and Ö/ö are shared with the Swedish language, and even Å/å is needed by Swedish-speaking Finns. However, the Finnish multilingual keyboard adds new letters and punctuation to the functional layout.
The Norwegian keyboard largely resembles the Swedish layout, but the and are replaced with and . The Danish keyboard is also similar, but it has the and swapped. On some systems, the Swedish or Finnish keyboard may allow typing Ø/ø and Æ/æ by holding the or key while striking and , respectively.
The Swedish with Sámi keyboard allows typing not only and , but even the letters required to write various Sámi languages. This keyboard has the same function for all the keys engraved on the regular Swedish keyboard, and the additional letters are available through the key.
On Macintosh computers, the Swedish and Swedish Pro keyboards differ somewhat from the image shown above, especially as regards the characters available using the or keys. (on the upper row) produces the sign, and produces the sign. The digit keys produce with and with .
On Linux systems, the Swedish keyboard may also give access to additional characters as follows:
first row: and
second row: and
third row: and
fourth row: and
Several of these characters function as dead keys.
Turkish
As of 2022, the majority of Turkish keyboards are based on QWERTY (the so-called Q-keyboard layout), although there is also the older F-keyboard layout specifically designed for the language.
Vietnamese
The Vietnamese keyboard layout is an extended Latin QWERTY layout. The letters Ă, Â, Ê, and Ô are found on what would be the number keys – on the US English keyboard, with – producing the tonal marks (grave accent, hook, tilde, acute accent and dot below, in that order), producing Đ, producing the đồng sign (₫) when not shifted, and brackets () producing Ư and Ơ.
Multilingual variants
Multilingual keyboard layouts, unlike the default layouts supplied for one language and market, try to make it possible for the user to type in any of several languages using the same number of keys. Mostly this is done by adding a further virtual layer in addition to the -key by means of (or 'right ' reused as such), which contains a further repertoire of symbols and diacritics used by the desired languages.
This section also tries to arrange the layouts in ascending order by the number of possible languages and not chronologically according to the Latin alphabet as usual.
Canadian CSA Z243.200:92
The CSA keyboard layout (also named Canadian Multilingual Standard – CMS) is used by some Canadians, mostly in Quebec and New-Brunswick. Though the caret (^) is missing, it is easily inserted by typing the circumflex accent followed by a space. This layout use three levels and two groups, up to 5 characters per key. Alt-Gr key is used to type a character on the level 3 and the Group 2 has a dedicated key instead of the Right-Ctrl .
United Kingdom (Extended) Layout
Windows
From Windows XP SP2 onwards, Microsoft has included a variant of the British QWERTY keyboard (the "United Kingdom Extended" keyboard layout) that can additionally generate several diacritical marks. This supports input on a standard physical UK keyboard for many languages without changing positions of frequently used keys, which is useful when working with text in Welsh, Scottish Gaelic and Irish — languages native to parts of the UK (Wales, parts of Scotland and Northern Ireland respectively).
In this layout, the grave accent key () becomes, as it also does in the US International layout, a dead key modifying the character generated by the next key pressed. The apostrophe, double-quote, tilde and circumflex (caret) keys are not changed, becoming dead keys only when 'shifted' with . Additional precomposed characters are also obtained by shifting the 'normal' key using the key. The extended keyboard is software installed from the Windows control panel, and the extended characters are not normally engraved on keyboards.
The UK Extended keyboard uses mostly the AltGr key to add diacritics to the letters a, e, i, n, o, u, w and y (the last two being used in Welsh) as appropriate for each character, as well as to their capitals. Pressing the key and then a character that does not take the specific diacritic produces the behaviour of a standard keyboard. The key presses followed by spacebar generate a stand-alone mark.:
grave accents (e.g. à, è, etc.) needed for Scots Gaelic are generated by pressing the grave accent (or 'backtick') key , which is a dead key, then the letter. Thus produces à.
acute accents (e.g. á) needed for Irish are generated by pressing the key together with the letter (or acting as a dead key combination followed by the letter). Thus produces á; produces Á. (Some programs use the combination of and a letter for other functions, in which case the method must be used to generate acute accents).
the circumflex diacritic needed for Welsh may be added by , acting as a dead key combination, followed by the letter. Thus then produces â, then produces the letter ŵ.
Some other languages commonly studied in the UK and Ireland are also supported to some extent:
diaeresis or umlaut (e.g. ä, ë, ö, etc.) is generated by a dead key combination , then the letter. Thus produces ä.
tilde (e.g. ã, ñ, õ, etc., as used in Spanish and Portuguese) is generated by dead key combination , then the letter. Thus produces ã.
cedilla (e.g. ç) under c is generated by , and the capital letter (Ç) is produced by
The and letter method used for acutes and cedillas does not work for applications which assign shortcut menu functions to these key combinations.
These combinations are intended to be mnemonic and designed to be easy to remember: the circumflex accent (e.g. â) is similar to the free-standing circumflex (caret) (^), printed above the key; the diaeresis/umlaut (e.g. ö) is visually similar to the double-quote (") above on the UK keyboard; the tilde (~) is printed on the same key as the .
The UK Extended layout is almost entirely transparent to users familiar with the UK layout. A machine with the extended layout behaves exactly as with the standard UK, except for the rarely used grave accent key. This makes this layout suitable for a machine for shared or public use by a user population in which some use the extended functions.
Despite being created for multilingual users, UK-Extended in Windows does have some gaps — there are many languages that it cannot cope with, including Romanian and Turkish, and all languages with different character sets, such as Greek and Russian. It also does not cater for thorn (þ, Þ) in Old English, the ß in German, the œ in French, nor for the å, æ, ø, ð, þ in Nordic languages.
ChromeOS
The UK Extended layout in ChromeOS provides all the same combinations as with Windows, but adds many more symbols and dead keys via AltGr.
Notes: Dotted circle (◌) is used here to indicate a dead key. The key is the only one that acts as a free-standing dead key and thus does not respond as shown on the key-cap. All others are invoked by AltGr.
(°) is a degree sign; (º) is a masculine ordinal indicator
Dead keys
produces grave accents (e.g., ) ( produces a standalone grave sign).
(release) produces diaeresis accents (e.g., )
(release) produces circumflex accents (e.g., )
(release) produces (mainly) comma diacritic or cedilla below the letter e.g.,
(release) produces a hook (diacritic) on vowels (e.g., )
AltGr+[ same as AltGr+2
AltGr+] same as AltGr+#
(release) produces overrings (e.g., )
(release) produces macrons (e.g., )
(release) produces mainly horn (diacritic)s (e.g., )
(release) produces an adjacent horn (e.g., )
(release) produces acute accents (e.g., )
(release) produces double acute accents on some letters (e.g., ) that exist in Unicode as pre-composed characters
(release) produces acute accents (e.g., )
(release) produces caron (haček) diacritics (e.g., )
(release) produces tilde diacritics (e.g., )
(release) produces inverted breve diacritics (e.g., )
(release) produces mainly underdots (e.g., )
(release) produces mainly overdots (e.g., )
Finally, any arbitrary Unicode glyph can be produced given its hexadecimal code point: , release, then the hex value, then or . For example (release) produces the Ethiopic syllable SEE, ሴ.
US-International
Windows and Linux
An alternative layout uses the physical US keyboard to type diacritics in some operating systems (including Windows). This is the US-International layout setting, which uses the right key as an key to support many additional characters directly as an additional shift key. (Since many smaller keyboards do not have a right- key, Windows also allows + to be used as a substitute for .) This layout also uses keys , , , and as dead keys to generate characters with diacritics by pressing the appropriate key, then the letter on the keyboard. The international keyboard is a software setting installed from the Windows control panel or similar; the additional functions (shown in blue) may or may not be engraved on the keyboard, but are always functional. It can be used to type most major languages from Western Europe: Afrikaans, Danish, Dutch, English, Faroese, German, Icelandic, Irish, Italian, Norwegian, Portuguese, Scottish Gaelic, Spanish, and Swedish. On Windows, it is not sufficient for French because it lacks the grapheme "œ/Œ" (as does every keyboard layout provided by Windows except the Canadian multilingual standard keyboard). Some less common western and central European languages (such as Welsh, Maltese, Czech, Finnish, Estonian and Hungarian), are not fully supported by the US-International keyboard layout because of their use of additional diacritics or precomposed characters.
A diacritic key is activated by pressing and releasing it, then pressing the letter that requires the diacritic. After the two strokes, the single character with diacritics is generated. Note that only certain letters, such as vowels and "n", can have diacritics in this way.
To generate an accented character with one of the diacritics , , , and , press the relevant accent key then the character to be accented. Characters with diacritics can be typed with the following combinations:
+ vowel → vowel with acute accent, e.g., → é
+ vowel → vowel with grave accent, e.g., → è
+ vowel → vowel with diaeresis (or umlaut), e.g., → ë
+ vowel → vowel with circumflex accent, e.g., → ê
+ , or → letter with tilde, e.g. → ñ, → õ
+ → ç (Windows) or ć (X11)
+ → ç (X11)
The US-International layout is not entirely transparent to users familiar with the conventional US layout; when using a machine with the international layout setting active, the commonly used single- and double-quote keys and the less commonly used grave accent, tilde, and circumflex (caret) keys are dead keys and thus behave unconventionally. This could be disconcerting on a machine for shared or public use.
There are also alternative US-International mappings, whereby modifier keys such as shift and alt are used, and the keys for the characters with diacritics are in different places from their unmodified counterparts. For example, the right-Alt key may be remapped as an AltGr modifier key or as a compose key and the dead key function deactivated, so that they (the ASCII quotation marks and circumflex symbol) can be typed normally with a single keystroke.
US-International in the Netherlands
The standard keyboard layout in the Netherlands is US-International, as it provides easy access to diacritics on common UK- or US-like keyboards. The Dutch layout is historical, and keyboards with this layout are rarely used. Many US keyboards sold do not have the extra US-International characters or engraved on the keys, although € () always is; nevertheless, the keys work as expected even if not marked. Many computer-literate Dutch people have retained the old habit of using + number codes to type accented characters; others routinely type without diacritics, then use a spelling checker to produce the correct forms.
Apple International English Keyboard
There are three kinds of Apple Keyboards for English: the United States, the United Kingdom and International English. The International English version features the same changes as the United Kingdom version, only without substituting for the symbol on , and as well lacking visual indication for the symbol on (although this shortcut is present with all Apple QWERTY layouts).
Differences from the US layout are:
The key is located on the left of the key, and the key is located on the right of the key.
The key is added on the left of the key.
The left key is shortened and the key has the shape of inverted L.
Finnish multilingual
The visual layout used in Finland is basically the same as the Swedish layout. This is practical, as Finnish and Swedish share the special characters Ä/ä and Ö/ö, and while the Swedish Å/å is unnecessary for writing Finnish, it is needed by Swedish-speaking Finns and to write Swedish family names which are common. However, it lacks the letters Š/š and Ž/ž which are used in some Finnish loanwords like šaahi 'shah' and džonkki 'junk'.
As of 2008, there is a new standard for the Finnish multilingual keyboard layout, developed as part of a localization project by CSC. All the engravings of the traditional Finnish–Swedish visual layout have been retained, so there is no need to change the hardware, but the functionality has been extended considerably, as additional characters (e.g., Æ/æ, Ə/ə, Ʒ/ʒ) are available through the key, as well as dead keys, which allow typing a wide variety of letters with diacritics (e.g., Ç/ç, Ǥ/ǥ, Ǯ/ǯ).
Based on the Latin letter repertory included in the Multilingual European Subset No. 2 (MES-2) of the Unicode standard, the layout has three main objectives. First, it provides for easy entering of text in both Finnish and Swedish, the two official languages of Finland, using the familiar keyboard layout but adding some advanced punctuation options, such as dashes, typographical quotation marks, and the non-breaking space (NBSP).
Second, it is designed to offer an indirect but intuitive way to enter the special letters and diacritics needed by the other three Nordic national languages (Danish, Norwegian and Icelandic) as well as the regional and minority languages (Northern Sámi, Southern Sámi, Lule Sámi, Inari Sámi, Skolt Sámi, Romani language as spoken in Finland, Faroese, Kalaallisut also known as Greenlandic, and German).
As a third objective, it allows for relatively easy entering of particularly names (of persons, places or products) in a variety of European languages using a more or less extended Latin alphabet, such as the official languages of the European Union (excluding Bulgarian and Greek). Some letters, like Ł/ł needed for Slavic languages, are accessed by a special "overstrike" key combination acting like a dead key.
However, the Romanian letters Ș/ș and Ț/ț (S/s and T/t with comma below) are not supported; the presumption is that Ş/ş and Ţ/ţ (with cedilla) suffice as surrogates.
EurKEY
EurKEY, a multilingual keyboard layout which is intended for Europeans, programmers and translators uses true QWERTY (US layout) as base just adding a third and fourth layer available through the key and +. These additional layers allows the users to type the symbolism of many European languages, special characters, the Greek alphabet (via dead keys), and many common mathematical symbols.
Unlike most of the other QWERTY layouts which are standards for a country or region, EurKEY is not a standard of the European Union, yet that is why a petition of EurKEY as European standard was started.
To address the ergonomics issue of QWERTY, EurKEY Colemak-DH was also developed a Colmak-DH version with the EurKEY design principals.
See also
Dvorak Simplified Keyboard, designed for Brazilian Portuguese
References
Informational notes
Citations
Latin-script keyboard layouts
Computing-related lists | List of QWERTY keyboard language variants | [
"Technology"
] | 9,979 | [
"Computing-related lists"
] |
69,086,733 | https://en.wikipedia.org/wiki/Institute%20of%20Seismological%20Research | Institute of Seismological Research (ISR) is a earthquake engineering and research center in Gandhinagar, India. In the aftermath of 2001 Gujarat earthquake, the institute was established by the Department of Science and Technology of Government of Gujarat in 2003.
History
In 2003, Dr. J. G. Negi formulated the framework for Institute of Seismological Research (ISR) and established the centre with the funding from Asian Development Bank. He resigned in 2004 due to differences arising between him and the state government. Later, Prof. Naveenchandra N. Srivastava was deputed by Gujarat government to lead the institute. Formal research activities were commenced in 2006.
ISR is the nodal agency in the western state of Gujarat to deploy and maintain a sub-network of 22 broadband seismograph stations and 40 strong-motion accelerographs. The sub-network is the part of the larger network called Indian National Strong-Motion Instrumentation Network, operated by Department of Earthquake Engineering, Indian Institute of Technology Roorkee.
See also
National Centre for Seismology
References
Gandhinagar
Earthquake engineering
Engineering research institutes
Seismological observatories, organisations and projects
2003 establishments in Gujarat | Institute of Seismological Research | [
"Engineering"
] | 242 | [
"Earthquake engineering",
"Civil engineering",
"Structural engineering",
"Engineering research institutes"
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69,086,804 | https://en.wikipedia.org/wiki/Strepsilin | Strepsilin is a chemical found in lichens. It produces an emerald green colour in the C test. It is a dibenzofuran dimer, with hydroxy, oxy and methyl side groups. It is named after Cladonia strepsilis. Strepsilin was discovered by Wilhelm Zopf in 1903. The structure of strepsilin was determined by Shoji Shibata.
Properties
Strepsilin is degraded in alkali to 1-methyl-3,7-dihydroxydibenzofuran.
Strepsilin melts at 324 °C.
Occurrence
Strepsilin is found in some Cladonia species. It is also found in Siphula and Stereocaulon azoreum.
References
Dibenzofurans
Furanones
Isobenzofurans
Hydroxyarenes
Lichen products
Heterocyclic compounds with 4 rings
Diols | Strepsilin | [
"Chemistry"
] | 196 | [
"Natural products",
"Lichen products"
] |
69,086,923 | https://en.wikipedia.org/wiki/Taurob%20Inspector | Taurob Inspector is an ATEX certified mobile robot, developed and manufactured by the Austrian company Taurob GmbH. The Inspector was developed from the Taurob Tracker as part of the OGRIP (Offshore Ground Robotics Industrial Pilot) project.
History
Project inception
With Taurob's victory in the ARGOS challenge, the commercially available Taurob Tracker in addition to the ARGOS robot were evaluated for operational use within an Oil & Gas environment. From this evaluation the foundation specification for the Taurob Inspector was created with the first prototypes being developed in early 2018.
First deployments
Taurob inspects are currently being operated on a 12 month deployment on Total Energies' Shetland Gas Plant.
World first offshore deployment
The first ever offshore deployment of an ATEX certified robot in 2020 on Total Energies' K5 gas field 110km off the coast of the Netherlands.
Production centre
In 2021 Taurob opened a subsidiary for the serial manufacture of robots - "Taurob Services S.A.S" with partner Dietsmann Smart Labs, a 100% subsidiary of Dietsmann NV. The subsidiary is based in Salies-du-Salat, France and is housed within Dietsmann's 24,000m² engineering and construction site. The inspector is the first robot to be produced by this venture, with the first robots leaving the production line in Q3 2021.
Technical specification
References
External links
Official Website (English)
Science and technology in Austria
Robots | Taurob Inspector | [
"Physics",
"Technology"
] | 298 | [
"Physical systems",
"Machines",
"Robots"
] |
69,087,488 | https://en.wikipedia.org/wiki/Ford%20GT90%20engine | The engine used in the Ford GT90 concept sports car is a 90-degree, quad-turbocharged, V12 engine; which itself is based on the Ford Modular V8 engine. It was Ford's first V12 since their Lincoln division's Lincoln-Zephyr V12 engine in 1948.
A 6.0-liter V12 engine was used in the Ford Indigo concept, but that engine was based on the Ford Duratec V6 engine, which has no relation to the V12 used in the GT90, and is also less powerful.
Overview
The GT90's 48-valve V12 is constructed on an aluminium block and head, displaces 5.9-litres (5,927 cc), and produces an estimated and of torque. It has a redline of 6,300 rpm. It is equipped with a forced induction system that uses four Garrett T2 turbochargers. The engine architecture was based on the 90-degree Ford Modular engine family, based on the same architecture and bore as the 4.6-litre V8 engine, but with four more cylinders added, two more in each cylinder bank, and a shorter stroke. This yielded a 90-degree V12, with a bore and a stroke with the cylinders arranged in two banks in a single casting.
The V12 engine, unique to the GT90, was developed by using a Lincoln Town Car as a test mule, in which they put the prototype engine in order to refine it.
Applications
Ford GT90
References
Engines by model
Ford engines
V12 engines | Ford GT90 engine | [
"Technology"
] | 319 | [
"Engines",
"Engines by model"
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69,087,630 | https://en.wikipedia.org/wiki/Porsche%20V8%20engine | Porsche has made a number of V8 gasoline engines over the last 40 years; ever since their first V8 engine debuted in the Porsche 928, in 1977.
Background
Porsche's V8 engine is currently in its fourth consecutive generation. July 8, 2016, marked the 40-year anniversary since their first engine rolled off the production line, in the 928. Under the hood was an engine that had never been used before; an eight-cylinder engine with a 90° V-angle, and water-cooling.
1977: First Generation
Porsche began a fresh chapter in engine building with the V-engine: The eight-cylinder engine was made up of essentially all lightweight alloys. As is characteristic with Porsche, it started a new era of engine construction. This was the first time in Europe that an engine was leaving the assembly line whose cylinder linings were engraved from cast aluminum. The 4.5-liter engine had a noticeably low compression ratio of 8.5:1. This meant it would be able to use normal 91-octane gasoline without any problems, which was extremely crucial to Porsche. However, this also restricted power rating, which was still at the more economical end of the range of possibilities. Their eight-cylinder engine made 176 kW (240 hp) at a moderate 5,500 rpm, which was sufficient for a top speed of 230 km/h. The engine’s nominal torque was 350 Nm at 3,600 rpm.
Progressively, Porsche engineers leveraged the potential within the eight-cylinder engine. The 928 S debuted at the 1979 IAA car show. Its engine had bores that were two millimeters larger, which meant an engine displacement of 4.7 liters. Its compression ratio increased to 10.0:1, which required the use of super gasoline. Nonetheless, the powerplant sparkled with a large power boost to 221 kW (300 hp). This allowed the 928 S to break the 250 km/h speed barrier. Later, another increase of the compression ratio and a switch over to electronic fuel injection made another improvement in power to 228 kW (310 hp).
1986: Catalytic Converters and four-valves per cylinder
Porsche engineers presented their next trump in 1986. Over the course of introducing catalytic converter technology, including in Europe, the eight-cylinder engine received its most substantial redesign. The new CAT version had completely redesigned cylinder heads with four valves per combustion chamber and two camshafts per cylinder bank. Increasing the bore to 100 mm increased engine size to about five liters. The eight-cylinder engine with emissions control began with 212 kW (288 hp). Its power limit was set by its low compression ratio, because initially, only standard unleaded gasoline was available in Europe. This barrier fell in 1987 with the introduction of the 928 S4, whose five-liter engine was created for super gasoline, now producing 235 kW (320 hp). After two years, a GT variant was built, which created 243 kW (330 hp), thanks to sharper valve timing control. Manufacturing of the 928 model line ended in 1995, and this also denoted the end of the first era of eight-cylinder V-engines from Porsche.
2002: Second Generation
Seven years later, after production ended for the first generation engine, a third Porsche model line with a redesigned eight-cylinder engine caused quite a response. The sports car manufacturer had started on the new Cayenne SUV. The new engine line, with its entirely new design, constituted two engines. The 4.5-liter naturally-aspirated engine in the Cayenne S already produced 250 kW (340 hp). The new top-of-the-line eight-cylinder was an engine in its own class, with twin-turbocharging, and 331 kW (450 hp) of power from the same base engine. It catapulted the Cayenne Turbo into the highest class of the quickest SUVs of its time.
Three years after the turbocharged eight-cylinder engine made its debut, Porsche went to work to develop it into the engine of the Cayenne Turbo S. 383 kilowatts or 521 hp at 5,500 rpm – this made the new SUV the second most powerful production Porsche car ever built; behind the Carrera GT sports car.
2007: Gasoline Direct Injection
In 2007, Porsche introduced an updated and reworked Cayenne model line-up, whose engines were switched over to gasoline direct injection. To increase power, bores that were three millimeters larger raised engine displacement to 4.8 liters. The Cayenne Turbo also received new turbochargers with larger radial turbines. Afterward, the eight-cylinder engine in the Cayenne S had an output of 283 kW (385 hp). The turbo engine now made 368 kW (500 hp) of power. The start of direct fuel injection was a key part in decreasing fuel consumption figures of the Cayenne models in the New European Driving Cycle (NEDC) by an average of eight percent.
2009: Panamera
In 2009, Porsche presented the Panamera as its fourth model line, and with the Gran Turismo, two more development stages of the eight-cylinder engines. The adjusted exhaust system and optimized engine control of the naturally-aspirated engine produced 294 kW (400 hp) of boosted power and a nominal torque of 500 Nm. In the Panamera Turbo, the 4.8-liter V8 twin-turbo engine provided 368 kW (500 hp) and a maximum torque of 700 Nm. The extensive use of lightweight alloys and design improvements also decreased engine mass by several kilograms. Less than 12 months later, these engines were introduced into the Cayenne models as well.
Porsche produced even higher-powered versions for the exceptionally sports models of the Panamera and Cayenne. The eight-cylinder naturally-aspirated engine elevated the power of the Panamera GTS to 316 kW (430 hp), and in the Cayenne GTS to 309 kW (420 hp). The turbocharged engine in the Cayenne Turbo raised engine output to 382 kW (520 hp), in the Panamera Turbo S to 405 kW (550 hp), and in the Cayenne Turbo S in several stages up to 419 kW (570 hp).
2013: Third Generation
When the third, completely re-developed V-8 from Porsche went into production in 2013, it wasn’t the engine itself that was the primary focus of attention, rather it was its counterpart: the electric drive. The 918 Spyder was the first super sports car to implement a hybrid drive system.
Its primary source of power was a detuned racing engine; similar to the Carrera GT's engine. At 132 hp/liter displacement, it had the world’s highest specific power of a street-legal naturally-aspirated engine, and at the same time, it was the lightest production naturally-aspirated V-8 engine, weighing only 135 kilograms. Rotating inside the eight-cylinder engine with its normal 90-degree cylinder bank angle, was a flat-plane crankshaft with 180-degree offset crank throws for the connecting rods.
Direct fuel injection
The MR6 engine was designed completely in-house by Porsche engineers with help from Penske Racing. The 3.4-litre 90-degree V8 racing engine was designed from scratch; and drove the rear wheels through a six-speed electro-pneumatic sequential gearbox. Since its introduction in 2005 the engine, which initially produced has been developed and modified to meet the changing regulations of both the ALMS and the ACO. For 2008 the engine developed using direct fuel injection and in 2009-spec with air restrictor limitations.
The 4.6-liter engine was derived directly from the engine of the successful RS Spyder. It outputted 447 kW (608 hp) at 8,700 rpm. Porsche engineers created direct fuel injection with centrally located solenoid injectors – an especially efficient and low-emission combustion process. These injectors send fuel into the combustion chambers at pressures up to 200 bar through seven holes each. Extensive lightweight design measures meant such features as titanium connecting rods and thin-walled low-pressure castings of the crankcase and the cylinder heads.
The eight-cylinder V-engine emotionalized the 918 Spyder by its performance abilities and by its sound. In addition to the ignition sequence, this is attributable first and foremost to what is known as the “top pipes”: the tailpipes stop at the upper part of the rear end right above the engine. No other production vehicle used this solution. The top pipes’ greatest technical advantage is optimal heat rejection, since hot gases are exhausted via the shortest possible path, and exhaust gas back pressure remains low.
This type of HSI engine design, where HSI means “hot side inside,” the 918 engine created a solid foundation for the new eight-cylinder engine of the Panamera. It contains the spirit of forty years of V-8 engines from Porsche.
2023: Porsche 963 LMDh
For the Porsche 963 LMDh the V8 engine was derived from the Porsche 918 Spyder sharing about 80 of its components. At 4.6 liter and a power output of 500 kW (680 PS) including the hybrid system. The engine weighs about 180 kg. Within the 90 degree hot V twin vanderlee Turbo systems are mounted.
Applications
Road cars
Porsche 928
Porsche Cayenne
Porsche Panamera
Porsche 918
Race Cars
Porsche RS Spyder
Porsche 963
References
Engines by model
Gasoline engines by model
Porsche
V8 engines
Porsche in motorsport | Porsche V8 engine | [
"Technology"
] | 1,970 | [
"Engines",
"Engines by model"
] |
69,087,855 | https://en.wikipedia.org/wiki/Lorentz%20oscillator%20model | The Lorentz oscillator model describes the optical response of bound charges. The model is named after the Dutch physicist Hendrik Antoon Lorentz. It is a classical, phenomenological model for materials with characteristic resonance frequencies (or other characteristic energy scales) for optical absorption, e.g. ionic and molecular vibrations, interband transitions (semiconductors), phonons, and collective excitations.
Derivation of electron motion
The model is derived by modeling an electron orbiting a massive, stationary nucleus as a spring-mass-damper system. The electron is modeled to be connected to the nucleus via a hypothetical spring and its motion is damped by via a hypothetical damper. The damping force ensures that the oscillator's response is finite at its resonance frequency. For a time-harmonic driving force which originates from the electric field, Newton's second law can be applied to the electron to obtain the motion of the electron and expressions for the dipole moment, polarization, susceptibility, and dielectric function.
Equation of motion for electron oscillator:
where
is the displacement of charge from the rest position,
is time,
is the relaxation time/scattering time,
is a constant factor characteristic of the spring,
is the effective mass of the electron,
is the resonance frequency of the oscillator,
is the elementary charge,
is the electric field.
For time-harmonic fields:
The stationary solution of this equation of motion is:
The fact that the above solution is complex means there is a time delay (phase shift) between the driving electric field and the response of the electron's motion.
Dipole moment
The displacement, , induces a dipole moment, , given by
is the polarizability of single oscillator, given by
Three distinct scattering regimes can be interpreted corresponding to the dominant denominator term in the dipole moment:
Polarization
The polarization is the dipole moment per unit volume. For macroscopic material properties N is the density of charges (electrons) per unit volume. Considering that each electron is acting with the same dipole moment we have the polarization as below
Electric displacement
The electric displacement is related to the polarization density by
Dielectric function
The complex dielectric function is given the following (in Gaussian units):
where and is the so-called plasma frequency.
In practice, the model is commonly modified to account for multiple absorption mechanisms present in a medium. The modified version is given by
where
and
is the value of the dielectric function at infinite frequency, which can be used as an adjustable parameter to account for high frequency absorption mechanisms,
and is related to the strength of the th absorption mechanism,
.
Separating the real and imaginary components,
Complex conductivity
The complex optical conductivity in general is related to the complex dielectric function
Substituting the formula of in the equation above we obtain
Separating the real and imaginary components,
See also
Cauchy equation
Sellmeier equation
Forouhi–Bloomer model
Tauc–Lorentz model
Brendel–Bormann oscillator model
References
Condensed matter physics
Electric and magnetic fields in matter
Optics | Lorentz oscillator model | [
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69,088,046 | https://en.wikipedia.org/wiki/Probabilistic%20numerics | Probabilistic numerics is an active field of study at the intersection of applied mathematics, statistics, and machine learning centering on the concept of uncertainty in computation. In probabilistic numerics, tasks in numerical analysis such as finding numerical solutions for integration, linear algebra, optimization and simulation and differential equations are seen as problems of statistical, probabilistic, or Bayesian inference.
Introduction
A numerical method is an algorithm that approximates the solution to a mathematical problem (examples below include the solution to a linear system of equations, the value of an integral, the solution of a differential equation, the minimum of a multivariate function). In a probabilistic numerical algorithm, this process of approximation is thought of as a problem of estimation, inference or learning and realised in the framework of probabilistic inference (often, but not always, Bayesian inference).
Formally, this means casting the setup of the computational problem in terms of a prior distribution, formulating the relationship between numbers computed by the computer (e.g. matrix-vector multiplications in linear algebra, gradients in optimization, values of the integrand or the vector field defining a differential equation) and the quantity in question (the solution of the linear problem, the minimum, the integral, the solution curve) in a likelihood function, and returning a posterior distribution as the output. In most cases, numerical algorithms also take internal adaptive decisions about which numbers to compute, which form an active learning problem.
Many of the most popular classic numerical algorithms can be re-interpreted in the probabilistic framework. This includes the method of conjugate gradients, Nordsieck methods, Gaussian quadrature rules, and quasi-Newton methods. In all these cases, the classic method is based on a regularized least-squares estimate that can be associated with the posterior mean arising from a Gaussian prior and likelihood. In such cases, the variance of the Gaussian posterior is then associated with a worst-case estimate for the squared error.
Probabilistic numerical methods promise several conceptual advantages over classic, point-estimate based approximation techniques:
They return structured error estimates (in particular, the ability to return joint posterior samples, i.e. multiple realistic hypotheses for the true unknown solution of the problem)
Hierarchical Bayesian inference can be used to set and control internal hyperparameters in such methods in a generic fashion, rather than having to re-invent novel methods for each parameter
Since they use and allow for an explicit likelihood describing the relationship between computed numbers and target quantity, probabilistic numerical methods can use the results of even highly imprecise, biased and stochastic computations. Conversely, probabilistic numerical methods can also provide a likelihood in computations often considered "likelihood-free" elsewhere
Because all probabilistic numerical methods use essentially the same data type – probability measures – to quantify uncertainty over both inputs and outputs they can be chained together to propagate uncertainty across large-scale, composite computations
Sources from multiple sources of information (e.g. algebraic, mechanistic knowledge about the form of a differential equation, and observations of the trajectory of the system collected in the physical world) can be combined naturally and inside the inner loop of the algorithm, removing otherwise necessary nested loops in computation, e.g. in inverse problems.
These advantages are essentially the equivalent of similar functional advantages that Bayesian methods enjoy over point-estimates in machine learning, applied or transferred to the computational domain.
Numerical tasks
Integration
Probabilistic numerical methods have been developed for the problem of numerical integration, with the most popular method called Bayesian quadrature.
In numerical integration, function evaluations at a number of points are used to estimate the integral of a function against some measure . Bayesian quadrature consists of specifying a prior distribution over and conditioning this prior on to obtain a posterior distribution over , then computing the implied posterior distribution on . The most common choice of prior is a Gaussian process as this allows us to obtain a closed-form posterior distribution on the integral which is a univariate Gaussian distribution. Bayesian quadrature is particularly useful when the function is expensive to evaluate and the dimension of the data is small to moderate.
Optimization
Probabilistic numerics have also been studied for mathematical optimization, which consist of finding the minimum or maximum of some objective function given (possibly noisy or indirect) evaluations of that function at a set of points.
Perhaps the most notable effort in this direction is Bayesian optimization, a general approach to optimization grounded in Bayesian inference. Bayesian optimization algorithms operate by maintaining a probabilistic belief about throughout the optimization procedure; this often takes the form of a Gaussian process prior conditioned on observations. This belief then guides the algorithm in obtaining observations that are likely to advance the optimization process. Bayesian optimization policies are usually realized by transforming the objective function posterior into an inexpensive, differentiable acquisition function that is maximized to select each successive observation location. One prominent approach is to model optimization via Bayesian sequential experimental design, seeking to obtain a sequence of observations yielding the most optimization progress as evaluated by an appropriate utility function. A welcome side effect from this approach is that uncertainty in the objective function, as measured by the underlying probabilistic belief, can guide an optimization policy in addressing the classic exploration vs. exploitation tradeoff.
Local optimization
Probabilistic numerical methods have been developed in the context of stochastic optimization for deep learning, in particular to address main issues such as
learning rate tuning and line searches,
batch-size selection, early stopping,
pruning, and first- and second-order search directions.
In this setting, the optimization objective is often an empirical risk of the form defined by a dataset , and a loss that quantifies how well a predictive model parameterized by performs on predicting the target from its corresponding input .
Epistemic uncertainty arises when the dataset size is large and cannot be processed at once meaning that local quantities (given some ) such as the loss function itself or its gradient cannot be computed in reasonable time.
Hence, generally mini-batching is used to construct estimators of these quantities on a random subset of the data. Probabilistic numerical methods model this uncertainty explicitly and allow for automated decisions and parameter tuning.
Linear algebra
Probabilistic numerical methods for linear algebra
have primarily focused on solving systems of linear equations of the form and the computation of determinants .
A large class of methods are iterative in nature and collect information about the linear system to be solved via repeated matrix-vector multiplication with the system matrix with different vectors .
Such methods can be roughly split into a solution- and a matrix-based perspective, depending on whether belief is expressed over the solution of the linear system or the (pseudo-)inverse of the matrix .
The belief update uses that the inferred object is linked to matrix multiplications or via and .
Methods typically assume a Gaussian distribution, due to its closedness under linear observations of the problem. While conceptually different, these two views are computationally equivalent and inherently connected via the right-hand-side through .
Probabilistic numerical linear algebra routines have been successfully applied to scale Gaussian processes to large datasets. In particular, they enable exact propagation of the approximation error to a combined Gaussian process posterior, which quantifies the uncertainty arising from both the finite number of data observed and the finite amount of computation expended.
Ordinary differential equations
Probabilistic numerical methods for ordinary differential equations , have been developed for initial and boundary value problems. Many different probabilistic numerical methods designed for ordinary differential equations have been proposed, and these can broadly be grouped into the two following categories:
Randomisation-based methods are defined through random perturbations of standard deterministic numerical methods for ordinary differential equations. For example, this has been achieved by adding Gaussian perturbations on the solution of one-step integrators or by perturbing randomly their time-step. This defines a probability measure on the solution of the differential equation that can be sampled.
Gaussian process regression methods are based on posing the problem of solving the differential equation at hand as a Gaussian process regression problem, interpreting evaluations of the right-hand side as data on the derivative. These techniques resemble to Bayesian cubature, but employ different and often non-linear observation models. In its infancy, this class of methods was based on naive Gaussian process regression. This was later improved (in terms of efficient computation) in favor of GaussMarkov priors modeled by the stochastic differential equation , where is a -dimensional vector modeling the first derivatives of , and where is a -dimensional Brownian motion. Inference can thus be implemented efficiently with Kalman filtering based methods.
The boundary between these two categories is not sharp, indeed a Gaussian process regression approach based on randomised data was developed as well. These methods have been applied to problems in computational Riemannian geometry, inverse problems, latent force models, and to differential equations with a geometric structure such as symplecticity.
Partial differential equations
A number of probabilistic numerical methods have also been proposed for partial differential equations. As with ordinary differential equations, the approaches can broadly be divided into those based on randomisation, generally of some underlying finite-element mesh and those based on Gaussian process regression.
Probabilistic numerical PDE solvers based on Gaussian process regression recover classical methods on linear PDEs for certain priors, in particular methods of mean weighted residuals, which include Galerkin methods, finite element methods, as well as spectral methods.
History and related fields
The interplay between numerical analysis and probability is touched upon by a number of other areas of mathematics, including average-case analysis of numerical methods, information-based complexity, game theory, and statistical decision theory. Precursors to what is now being called "probabilistic numerics" can be found as early as the late 19th and early 20th century.
The origins of probabilistic numerics can be traced to a discussion of probabilistic approaches to polynomial interpolation by Henri Poincaré in his Calcul des Probabilités.
In modern terminology, Poincaré considered a Gaussian prior distribution on a function , expressed as a formal power series with random coefficients, and asked for "probable values" of given this prior and observations for .
A later seminal contribution to the interplay of numerical analysis and probability was provided by Albert Suldin in the context of univariate quadrature. The statistical problem considered by Suldin was the approximation of the definite integral of a function , under a Brownian motion prior on , given access to pointwise evaluation of at nodes . Suldin showed that, for given quadrature nodes, the quadrature rule with minimal mean squared error is the trapezoidal rule; furthermore, this minimal error is proportional to the sum of cubes of the inter-node spacings. As a result, one can see the trapezoidal rule with equally-spaced nodes as statistically optimal in some sense — an early example of the average-case analysis of a numerical method.
Suldin's point of view was later extended by Mike Larkin.
Note that Suldin's Brownian motion prior on the integrand is a Gaussian measure and that the operations of integration and of point wise evaluation of are both linear maps.
Thus, the definite integral is a real-valued Gaussian random variable.
In particular, after conditioning on the observed pointwise values of , it follows a normal distribution with mean equal to the trapezoidal rule and variance equal to .
This viewpoint is very close to that of Bayesian quadrature, seeing the output of a quadrature method not just as a point estimate but as a probability distribution in its own right.
As noted by Houman Owhadi and collaborators, interplays between numerical approximation and statistical inference can also be traced back to Palasti and Renyi, Sard, Kimeldorf and Wahba (on the correspondence between Bayesian estimation and spline smoothing/interpolation) and Larkin (on the correspondence between Gaussian process regression and numerical approximation). Although the approach of modelling a perfectly known function as a sample from a random process may seem counterintuitive, a natural framework for understanding it can be found in information-based complexity (IBC), the branch of computational complexity founded on the observation that numerical implementation requires computation with partial information and limited resources. In IBC, the performance of an algorithm operating on incomplete information can be analyzed in the worst-case or the average-case (randomized) setting with respect to the missing information. Moreover, as Packel observed, the average case setting could be interpreted as a mixed strategy in an adversarial game obtained by lifting a (worst-case) minmax problem to a minmax problem over mixed (randomized) strategies. This observation leads to a natural connection between numerical approximation and Wald's decision theory, evidently influenced by von Neumann's theory of games. To describe this connection consider the optimal recovery setting of Micchelli and Rivlin in which one tries to approximate an unknown function from a finite number of linear measurements on that function. Interpreting this optimal recovery problem as a zero-sum game where Player I selects the unknown function and Player II selects its approximation, and using relative errors in a quadratic norm to define losses, Gaussian priors emerge as optimal mixed strategies for such games, and the covariance operator of the optimal Gaussian prior is determined by the quadratic norm used to define the relative error of the recovery.
Software
ProbNum: Probabilistic Numerics in Python.
ProbNumDiffEq.jl: Probabilistic numerical ODE solvers based on filtering implemented in Julia.
Emukit: Adaptable Python toolbox for decision-making under uncertainty.
BackPACK: Built on top of PyTorch. It efficiently computes quantities other than the gradient.
See also
Average-case analysis
Information-based complexity
Uncertainty quantification
References
Applied statistics
Machine learning
Applied mathematics | Probabilistic numerics | [
"Mathematics",
"Engineering"
] | 2,931 | [
"Artificial intelligence engineering",
"Applied mathematics",
"Applied statistics",
"Machine learning"
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69,088,541 | https://en.wikipedia.org/wiki/Mussel%20toxic%20peptide | Mussel toxic peptide (MTP) is a marine biotoxin that can be found in mussels of the species Mytilus edulis (blue mussel) that are contaminated by mycotoxins produced by fungi of the genus Trichoderma. MTP is a voltage-gated sodium channel blocker, which has a mild effect on voltage-gated potassium channels.
Discovery and distribution
MTP was extracted from mussels harvested from Bizerte lagoon, located in the north of Tunisia. It was first discovered during investigation of the cause of a yearly repetitive food poisoning occurring after consumption of mussels from Bizerte lagoon during the autumn-winter season. During this season, changes in temperature and precipitation, which contains phosphates and nitrogen, contribute to conditions that are favourable for the growth of microorganisms that contaminate the siphon of the mussels. As with other marine biotoxins, it is difficult to track MTP’s origin but its occurrence has been increasing over the last decade due to changes in the local environment. This toxin found in mussels appears to contain two fractions, namely C17-sphinganine analog mycotoxin (C17-SAMT) and MTP. C17-SAMT has been found earlier in spoiled food and belongs to a family of toxins produced by fungi (sphinganine-analog mycotoxins). While the C17-SAMT fraction has been studied before., MTP was only investigated recently.
Chemistry
Homology and family
MTP belongs to a wider group of marine biotoxins. Based on the clinical symptoms that they induce, marine biotoxins are distinguished in two groups: diarrhetic shellfish poisoning toxins and marine neurotoxic biotoxins. The grouping of marine biotoxins is also delineated based on their mechanism of action, where MTP is included into the channel-blocking neurotoxin family. As cases were not (at least not systematically) reported until the last decade, MTP might be a newly introduced toxin, coming from a species that was recently brought into the Bizerte lagoon.
Structure
Unlike most other marine neurotoxins, MTP is proteinaceous and has a molecular mass of 6.4kDa, which is large compared to the masses of other marine biotoxins. While its toxicity has been investigated, the exact structure of MTP remains unclear.
Target and mode of action
MTP blocks voltage-gated sodium channels, but has an almost negligible effect on potassium channels. In mouse neuroblastoma, the IC50 value was 4.5 μM for sodium and 102.1 μM for potassium channels, showing a much stronger affinity for sodium channels. MTP acts as a pore blocker on sodium channels.
Toxicity
Injection of MTP in mice caused symptoms of toxicity such as restlessness, breathing difficulties, paralysis of hind limbs and death in less than five minutes. Since a widespread chain of cases in humans has not been reported, its symptomatology has not yet been described.
References
Ion channel toxins
Proteins
Neurotoxins | Mussel toxic peptide | [
"Chemistry"
] | 657 | [
"Biomolecules by chemical classification",
"Molecular biology",
"Proteins",
"Neurochemistry",
"Neurotoxins"
] |
69,088,613 | https://en.wikipedia.org/wiki/Hinged%20arch%20bridge | A hinged arch bridge is one with hinges incorporated into its structure to allow movement. In structural engineering, a hinge is essentially a "cut in the structure" that can withstand compressive forces. In a steel arch the hinge allows free rotation, somewhat resembling a common hinge. The most common hinged arch bridge varieties are the two-hinged bridge with hinges at the springing points and the three-hinged bridge with an additional hinge at the crown of the arch; though single-hinged versions exist with a hinge only at the crown of the arch. Hinges at the springing point prevent bending moments from being transferred to the bridge abutments. A triple-hinged bridge is statically determinate, while the other versions are not.
Description
A fixed arch bridge, that is one without hinges, exerts a bending moment at the abutments and stresses caused by change of temperature or shrinkage of concrete have to be taken up by the arch. A two-hinged arch has a hinge at the base of each arch (the springing point), while a three-hinged arch has a third hinge at the crown of the arch. The advantage of the fixed arches is in their lower construction and maintenance costs.
In a two-hinged arch bridge no bending moments are transferred to the abutments, due to the presence of the hinge. A change in the relative position of the abutments may cause a change in the thrust load exerted by the arch on the abutments. The addition of a third hinge at the crown, which allows rotation of the arch members, means that the thrust and shear forces exerted on the abutments are not affected by small movements in either abutment. Three-hinged arch bridges are, therefore, used when there is the possibility of unequal settlement of the abutments. Single-hinged arch bridges, with a hinge only at the crown, were also built though in relatively small numbers compared to the other types.
A three hinged bridge is isostatic, that is it is statically determinate; a two-hinged bridge is statically indeterminate in one degree of freedom, while a fixed arch bridge is indeterminate in three degrees of freedom. The statically determinate three-hinged arches were popular until the Second World War. Post-war, the advances in calculation methods allowed broad use of statically indeterminate schemes. In the end of the 20th century three-hinged arches made a comeback associated with the uses of engineered wood ("glulam") in bridge construction: the glulam construction have to be pre-fabricated, using three-hinged design naturally divides the arch into two halves that are easier to transport.
While in steel arches hinges typically allow free rotation of connected parts, in reinforced concrete bridges typical implementation of a hinge involves thinning of the concrete structure while adding more reinforcement locally.
History
Early arch bridges were fixed arches. The two-hinged bridge was developed by the engineers Couche and Salle in 1858 for a wrought iron bridge carrying the Paris-Creil railway line across the Canal Saint-Denis. They had attempted to introduce a third hinge at the crown but were unsuccessful because the thickness of the arch was insufficient. The first three-hinged bridge was the Unterspree Bridge in Berlin (Johann Wilhelm Schwedler, 1863), built two years after the pioneering theoretical work by . Hradecky Bridge (1866) is probably the oldest three-hinged bridge still used.
Hinged bridges were popular with railway companies, who often had the need to construct large bridges. The Arch Bridge at Bellows Falls in New England, built in 1905, is a particularly large example of a three-hinged arch bridge. At in length it was the longest in America when built. The 1888 Hennepin Avenue Bridge in Minneapolis was unusual in that it was both a two- and three-hinged bridge. The bridge was split longitudinally with the two halves being built by different companies. The north arch ribs are three-hinged, while the south arch ribs are two-hinged. Three-hinged arch bridges remain popular in modern civil engineering.
References
Sources
Bridge design
Arch bridges | Hinged arch bridge | [
"Engineering"
] | 873 | [
"Structural engineering",
"Bridge design",
"Architecture"
] |
69,088,731 | https://en.wikipedia.org/wiki/Protoxin-I | Protoxin-I, also known as ProTx-I, or Beta/omega-theraphotoxin-Tp1a, is a 35-amino-acid peptide neurotoxin extracted from the venom of the tarantula Thrixopelma pruriens. Protoxin-I belongs to the inhibitory cystine knot (ICK) family of peptide toxins, which have been known to potently inhibit voltage-gated ion channels. Protoxin-I selectively blocks low voltage threshold T-type calcium channels, voltage gated sodium channels and the nociceptor cation channel TRPA1. Due to its unique ability to bind to TRPA1, Protoxin-I has been implicated as a valuable pharmacological reagent with potential applications in clinical contexts with regards to pain and inflammation
Origin
Protoxin-I is a toxin extracted from the venom of the tarantula spider Thrixopelma pruriens, also known as the Peruvian green velvet spider. It is used by the spider to immobilise and catch prey. The primary structure of the mature toxin peptide is homologous to that of Beta/omega-theraphotoxin-Bp1a from the tarantula spider Bumba pulcherrimaklaasi, suggesting a common toxin within the subfamily Theraphosinae.
Structure and active site
Protoxin-I is a peptide possessing a 35 amino acid sequence of Glu-Cys-Arg-Tyr-Trp-Leu-Gly-Gly-Cys-Ser-Ala-Gly-Gln-Thr-Cys-Cys-Lys-His-Leu-Val-Cys-Ser-Arg-Arg-His-Gly-Trp-Cys-Val-Trp-Asp-Gly-Thr-Phe-Ser (see Table 1 for one-letter sequence) with 3 disulphide bonds between Cys2-Cys16, Cys9-Cys21 and Cys15-Cys28. Nuclear Magnetic Resonance Spectroscopy of Protoxin-I revealed two beta strands in the protein structure. Gating-modifier toxins isolated from spider venom all share a conserved molecular structure consisting of a hydrophobic patch, populated by hydrophobic residues, and surrounded by a ring of positively- and negatively charged residues that promote the binding of the peptide to the lipid membrane.
By systematically exchanging single amino acids by an alanine, features responsible for Protoxin-I toxicity can be revealed. As such, the replacements R3A, W5A, K17E, L19A, S22A, R23A, W27A, V29A, W30A, D31A, G31A, F34A reduce the toxin's ability to inhibit sodium channels NaV1.2. Similarly, the replacements L6A, L19A, W27A, V29A, W30A, D31A also reduce its inhibitory effects on NaV1.7 sodium channels. Lastly, the replacements Q13A, L19A, S22A, W30A, F34A, S35A reveal the active sites for Protoxin-I binding to TRPA1 receptors. These loss-of-function replacements primarily represent residues in the hydrophobic patch and positively- and negatively charged rings, further supporting the idea that these regions play an important role in ion channel binding.
Toxicodynamics
Like other gating-modifier spider toxins, Protoxin-I preferentially binds to anionic lipid-containing membranes where it exhibits complex allosteric interactions with ion channel voltage sensor domains. After binding to the lipid membrane, Protoxin-I adopts a shallow position on the anionic membrane with the help of tryptophan residues within the hydrophobic patch, where the positively- and negatively charged rings on the toxin are then able to bind to conserved sequences of hydrophobic and anionic residues on voltage gated ion channels.
Voltage-gated sodium channels
Similar to other gating-modifier toxins of the ICK family, Protoxin-I works by shifting the voltage dependence of activation of voltage-gated sodium channels to more positive potentials. Protoxin-I differs from other ICK toxins as Protoxin-I exhibits little selectivity between sodium channels, and is thus able to potently inhibit TTX-resistant sodium currents in sensory neurons through interaction with the Nav1.8 channel. Protoxin-I has been found to potently bind to NaV1.2, NaV1.6, NaV1.7 and NaV1.8. The pore-forming α subunit of voltage-gated sodium channels consists of 4 homologous domains, each having their own voltage sensor domain. Research has shown that Protoxin-I interacts with the voltage sensor domains of domain II and domain IV, thereby functionally inhibiting the channel. Protoxin-I promiscuity in binding to voltage-gated sodium channels is believed to be because of the high amount of positively charged residues on the peptide surface, which bind to conserved amino acid sequences on the surface of the voltage-sensor domain on sodium channels. This notion is further back by the fact that Protoxin-I binds less potently to NaV1.4 and NaV1.5, which exhibit relatively fewer anionic residues on the voltage sensor domain.
Voltage-Gated T-type calcium channels
Protoxin-I has also been found to shift the voltage dependence of activation of the T-type calcium channels. In particular, Protoxin-I is able to differentiate CaV3.1 channels from other human T-type calcium channels, exhibiting a 160-fold increase in potency over that of CaV3.2, and a 10-fold increase in potency over that of CaV3.3. Protoxin-I shifts the voltage dependence of activation of T-type calcium channels to more positive potentials, without changing its voltage dependence of inactivation. Through the use of chimeric channel proteins, the S3-S4 linker on domain IV of the CaV3.1 channel protein has been identified in having greater sensitivity towards Protoxin-I, suggesting that this domain exhibits specific residues that are susceptible to Protoxin-I binding.
Transient receptor potential ankyrin 1 (TRPA1)
Protoxin was identified to be the first high-affinity peptide TRPA1 antagonist. TRPA1 is a primary nociceptor channel expressed on the plasma membrane of many human and animal cells. NaV1.2 and TRPA1 were found to have partially homologous binding sites by which Protoxin-I binds to these ion channels. These binding surfaces are, similar to that of sodium channels, located on the extracellular loops of the S1-S4 gating domain of the TRPA1 channel.
Therapeutic uses
In vivo testing in mice revealed that intrathecal injection of Protoxin-I reduces the response to formalin in acute pain and inflammation without signs of neurotoxicity.
Modifications to Protoxin-I can induce altered specificity in binding, producing peptides that only bind to either the TRPA1 or NaV1.2 gating mechanism. This may provide a deeper insight into the biophysiological function and mechanisms underlying TRPA1, with potential clinical applications in pain and inflammation treatment. TRPA1 represents the final common pathway for many pronociceptive induced pathophysiological pain, therefore, pain therapy using TRPA1 antagonists can be expected to have applicable pharmacological use
References
Ion channel toxins
Neurotoxins
Spider toxins | Protoxin-I | [
"Chemistry"
] | 1,598 | [
"Neurochemistry",
"Neurotoxins"
] |
69,088,742 | https://en.wikipedia.org/wiki/Semi-trailer%20aerodynamic%20device | Semi-trailer aerodynamic devices are devices affixed to semi-trailers, for the purpose of reducing aerodynamic drag caused by air turbulence. The two major types of device in use are trailer skirts (or side skirts), affixed to the underside of trailers, and trailer tails (or boat tails, or rear fairings), affixed to the rear. Several such devices have been recognized by the U.S. Environmental Protection Agency's SmartWay Transport Partnership, making them eligible for funding under the Diesel Emissions Reduction Act.
Trailer skirts
Construction
Trailer skirts comprise a pair of panels affixed to the lower side edges of a trailer, running most of the length of the trailer and filling the gap between the forward and rear axles. Trailer skirts are typically constructed of aluminum, plastic, or fiberglass, with plastic the most resistant to damage from side or bottom impacts. Skirts may have a modular design, allowing installation on a variety of trailer lengths. Skirts generally weigh between . Installation typically requires three to five .
Cost
, a set of trailer skirts cost between C$1500 and C$3000 (US$1300 to $2700). Standard trailer skirts have an estimated payback period of ten to eighteen months, while "advanced" skirts (those that improve fuel efficiency by over 7%) are estimated to pay for themselves in seven to fourteen months.
Performance
A 2012 investigation by SAE International of nine trailer skirt designs found that three provided fuel savings greater than 5%, and four provided savings between 4% and 5%, compared with an unmodified trailer. Skirts with reduced ground clearance offer greater fuel savings; in one instance, reducing ground clearance from to resulted in an improvement in fuel savings from 4% to 7%. One 2008 Delft University of Technology study found fuel savings of up to 15% for the particular design studied. Sean Graham, president of a major supplier of trailer skirts, estimates that in typical use, drivers see fuel savings of 5% to 6%.
Trailers with skirts fitted have also demonstrated reduced tire spray, and drivers have reported improved stability in crosswinds.
Adoption
As of 2018, over 60% of new trailers produced in Australia are equipped with skirts, whereas the figure is over 50% for the North American market.
A 2014 study by the North American Council for Freight Efficiency on adoption of fuel efficient technologies and practices found trailer skirts to be the most widely adopted technology of those studied, having been adopted by seven of the ten major shipping fleets in the study.
Since the wide adoption of trailer skirts, incidents of them becoming detached and colliding with other vehicles have increased. On October 18, 2018, a trailer skirt came off of a tractor trailer traveling East in Knoxville, Tennessee and hit a westbound car, killing its driver.
Trailer tails
Trailer tails, boat tails, or rear fairings comprise a set of panels, usually collapsible, which fold out from the rear of the trailer, creating a tapered shape that reduces drag from the low-pressure wake created behind the trailer. Trailer tails alone have demonstrated a fuel savings of 1%–5%, and in concert with trailer skirts, 9% improvement has been demonstrated.
TrailerTail is a registered trademark of STEMCO.
SuperTruck project
At least one model of trailer tail, trade named TrailerTail, is part of Navistar's SuperTruck project, which will use $37 million of US Department of Energy grants to build next generation trucks and tractor trailers.
See also
Teardrop trailer (truck), an aerodynamically shaped trailer in use in the UK
References
Vehicle parts
Automotive technologies
Shipping and the environment
Transportation engineering
Transport economics
Energy conservation | Semi-trailer aerodynamic device | [
"Technology",
"Engineering"
] | 733 | [
"Industrial engineering",
"Transportation engineering",
"Civil engineering",
"Vehicle parts",
"Components"
] |
69,089,298 | https://en.wikipedia.org/wiki/List%20of%20fungi%20of%20South%20Africa%20%E2%80%93%20E | This is an alphabetical list of fungal taxa as recorded from South Africa. Currently accepted names have been appended.
Ec
Genus: Echidnodella Theiss. & Syd. 1918
Echidnodella hypolepidis Doidge 1920accepted as Echidnodes hypolepidis (Doidge) Doidge, (1942)
Echidnodella natalensis (Doidge) Arx, (1962), recorded as Echidnodes natalensis (Doidge) Doidge 1942
Genus: Echidnodes Theiss. & Syd. 1918
Echidnodes acokantherae (Doidge) Doidge 1942, accepted as Lembosina acokantherae (Doidge) Arx [as 'acocantherae'],(1962)
Echidnodes africana (Doidge) Doidge 1942
Echidnodes curtisiae Doidge 1948
Echidnodes durbana (Van der Byl) Hansf. 1946 accepted as Lembosina durbana (Van der Byl) Arx, (1962)
Echidnodes hypolepidis (Doidge) Doidge 1942
Echidnodes natalensis (Doidge) Doidge 1942 accepted as Echidnodella natalensis (Doidge) Arx, (1962)
Echidnodes rhoina Doidge 1920 accepted as Lembosina rhoina (Doidge) Arx, (1962)
Echidnodes transvaalensis Doidge 1948
Genus: Ectotrichophyton Castell. & Chalm. 1919 accepted as Trichophyton Malmsten, (1848)
Ectotrichophyton mentagrophytes (C.P. Robin) Castell. & Chalm. 1919 accepted as Trichophyton mentagrophytes (C.P. Robin) Sabour., (1895)
El
Genus: Elmerococcum Theiss. & Syd. 1915, accepted as Botryosphaeria Ces. & De Not., (1863)
Elmerococcum peglerae (Pole-Evans) Doidge 1921
Genus: Elsinoë Racib. 1900
Elsinoë ampelina Shear 1929
Elsinoë fawcetti Bitanc. & Jenkins 1936
Elsinoë poinsettiae Jenkins (sic) possibly (Jenkins & Ruehle) Rossman & W.C. Allen 2016
Elsinoë pyri (Woron.) Jenkins 1932
Elsinoë violae Jenkins (sic) probably (Massey & Jenkins) X.L. Fan & Crous 2017
Em
Genus: Empusa Cohn 1855
Empusa conglomerata (Sorokīn) Thaxt. 1888 accepted as Entomophaga conglomerata (Sorokīn) S. Keller, [1987]
Empusa fresenii Nowak. 1886 accepted as Neozygites fresenii (Nowak.) Remaud. & S. Keller, (1980)
Empusa grylli (Fresen.) Nowak. 1888 accepted as Entomophaga grylli (Fresen.) A. Batko, (1964)
Empusa lecanii Zimm. 1901 accepted as Neozygites lecanii (Zimm.) Ben Ze'ev & R.G. Kenneth, (1987)
Empusa muscae Cohn 1855 accepted as Entomophthora muscae (Cohn) Fresen., (1856)
Empusa sp.
En
Genus: Endocarpiscum Nyl. 1864 (Lichens)
Endocarpiscum guepini (Delise) Nyl. 1864
Genus: Endocarpon Hedw. 1789
Endocarpon crenatum Taylor 1847 accepted as Psora crenata (Taylor) Reinke, (1895)
Endocarpon hepaticum Ach. 1809
Endocarpon peltatum Taylor 1847
Endocarpon pusillum Hedw. 1789
Endocarpon speireum Taylor 1847
Endocarpon vitellinum Spreng. 1820
Endocarpon thunbergii (Ach.) Ach. 1803 accepted as Dermatiscum thunbergii (Ach.) Nyl., (1867)
Genus: Endodermophyton Castell. 1910 accepted as Trichophyton Malmsten, (1848)
Endodermophyton africanum Doidge (sic) possibly C.W. Dodge 1935
Endodermophyton sp.
Genus: Endodothella Theiss. & Syd. 1915 accepted as Phyllachora Nitschke ex Fuckel, (1870)
Endodothella deightonii Syd. 1938 accepted as Stigmochora deightonii (Syd.) Arx, (1962)
Endodothella natalensis Doidge 1921 accepted as Stigmochora natalensis (Doidge) Arx, (1962)
Endodothella strelitziae (Cooke) Theiss. & Syd. 1915 accepted as Phyllachora strelitziae (Cooke) Sacc., (1883)
Order: Endomycetales Gäum. & C.W. Dodge 1928
Family: Endomycetaceae J. Schröt. 1893
Genus: Endophyllum Lév. 1826
Endophyllum macowanii Pole-Evans 1909 [as macowani]
Genus: Endopyrenium Flot. 1855 accepted as Catapyrenium Flot., (1850)
Endopyrenium peltatum (Taylor) Müll. Arg. 1888
Genus: Englerula Henn. 1904
Englerula macarangae Henn. 1904
Englerula popowiae Stevens.*
Genus: Englerulaster Höhn. 1910 accepted as Asterina Lév., (1845)
Englerulaster gymnosporiae (Henn.) Theiss. 1918 accepted as Englera gymnosporiae (Henn.) F. Stevens, (1939)
Englerulaster macowanianus (Thüm.) G. Arnaud 1918 accepted as Parenglerula macowaniana (Thüm.) Höhn., (1910)
Englerulaster orbicularis (Berk. & M.A. Curtis) Höhn. 1910 accepted as Cryptomeliola orbicularis (Berk. & M.A. Curtis) S. Hughes & Piroz., (1997)
Englerulaster popowiae Doidge 1920 accepted as Englera popowiae (Doidge) F. Stevens, (1939)
Genus: Enterographa Fée 1825 (Lichens)
Enterographa capensis A. Massal. 1861, accepted as Chiodecton colensoi (A. Massal.) Müll. Arg., (1894)
Enterographa galactina (Zahlbr.) Redinger 1938
Enterographa vanderbylii (Zahlbr.) Redinger 1938
Enterographa venosa (Pers.) A. Massal. 1860 accepted as Enterographa crassa (DC.) Fée, [1824]
Genus: Enterostigma Müll. Arg. 1885 accepted as Thelotrema Ach., (1803)
Enterostigma compunctum (Ach.) Müll. Arg. 1885 accepted as Leucodecton compunctum (Ach.) A. Massal., [1859-1860]
Genus: Entoloma P. Kumm. 1871
Entoloma erophilum (Fr.) P. Karst. 1879, accepted as Entoloma plebejum (Kalchbr.) Noordel., (1985)
Entoloma lividum Quél. 1872 accepted as Entoloma sinuatum (Bull.) P. Kumm., (1871)
Entoloma microcarpum (Berk. & Broome) Sacc. 1887 accepted as Termitomyces microcarpus (Berk. & Broome) R. Heim, (1942)
Entoloma sagittiforme (Kalchbr. & Cooke) Sacc. [as 'sagittaeforme'] 1887, accepted as Termitomyces sagittiformis (Kalchbr. & Cooke) D.A. Reid [as 'sagittaeformis'], (1975)
Genus Entomophaga A. Batko 1964,
Entomophaga conglomerata (Sorokīn) S. Keller, [1987] recorded as Empusa conglomerata (Sorokīn) Thaxt. 1888
Entomophaga grylli (Fresen.) A. Batko, (1964) recorded as Empusa grylli (Fresen.) Nowak. 1888
Genus: Entomophthora Fresen. 1856
Entomophthora aphidis H. Hoffm. 1858, accepted as Zoophthora aphidis (H. Hoffm.) A. Batko, (1964)
Entomophthora apiculata (Thaxt.) M.A. Gust. 1965 accepted as Batkoa apiculata (Thaxt.) Humber, (1989)
Entomophthora coronata (Costantin) Kevorkian 1937 accspted as Conidiobolus coronatus (Costantin) A. Batko, (1964) [1962]
Entomophthora grylli Fresen. 1856
Entomophthora megasperma (Cohn) Sacc. 1888 accepted as Tarichium megaspermum Cohn, (1875)
Entomophthora muscae (Cohn) Fresen., (1856) recorded as Empusa muscae Cohn 1855
Entomophthora sphaerosperma Fresen. 1856
Entomophthora sp.
Order: Entomophthorales G. Winter 1880
Family: Entomophthoraceae A.B. Frank 1874
Genus: EntomosporiumcLév. 1857 accepted as Diplocarpon F.A. Wolf, (1912)
Entomosporium maculatum Lév. 1856 accepted as Diplocarpon mespili (Sorauer) B. Sutton, (1980)
Genus: Entopeltis Höhn. 1910 accepted as Vizella Sacc., (1883)
Entopeltis interrupta (G. Winter) Höhn. 1910, accepted as Vizella interrupta (G. Winter) S. Hughes, (1953)
Genus: Entyloma de Bary 1874
Entyloma australe Speg. 1880
Entyloma bidentis Henn. 1895
Entyloma calendulae (Oudem.) de Bary 1874
Entyloma dahliae Syd. & P. Syd. 1912
Entyloma fuscum J. Schröt. 1877
Entyloma oleandrae Henn. 1895
Entyloma physalidis (Kalchbr. & Cooke) G. Winter 1883 accepted as Entyloma australe Speg., (1880)
Entyloma zinniae Syd. 1935
Ep
Family: Ephebaceae Th. Fr. 1861
Genus: Ephebe Fr. 1825
Ephebe lanata (L.) Vain. 1888
Ephebe pubescens (L.) Fr. 1826, accepted as Pseudephebe pubescens (L.) M. Choisy, (1930)
Genus: Ephelis Fr. 1849
Ephelis viridans (Kalchbr. & Cooke) Sacc. 1884
Genus: Epichloë (Fr.) Tul. & C. Tul. 1865
Epichloë cinerea Berk. & Broome 1873
Epichloë eragrostis (sic) Pole Evans probably Epichloe eragrostidis Pole-Evans, (1917)
Epichloë zahlbruckneriana Henn. 1900
Genus: Epicoccum Link 1816
Epicoccum chrysanthemi du Plessis 1933
Epicoccum granulatum Penz. 1882
Epicoccum humicola (R.E. Buchanan) Sacc. 1931
Epicoccum neglectum Desm. 1842
Epicoccum nigrum Link 1816
Epicoccum purpurascens Ehrenb. ex Schltdl. 1824 accepted as Epicoccum nigrum (1816)
Epicoccum sp.
Genus: Epidermophyton Sabour. 1907
Epidermophyton floccosum (Harz) Langeron & Miloch. 1930
Epidermophyton interdigitale (Priestley) L. MacCarthy 1925 accepted as Trichophyton mentagrophytes (C.P. Robin) Sabour., (1895)
Epidermophyton purpureum (H. Bang) C.W. Dodge 1935 accepted as Trichophyton purpureum H. Bang, (1910)
Epidermophyton rubrum Castell. 1910 accepted as Trichophyton rubrum (Castell.) Sabour., (1911)
Genus: Epistigme Syd. 1924
Epistigme nidulans Syd. 1924
Genus: Epochnium Link 1809 accepted as Monilinia Honey, (1928)
Epochnium phyllogenum Kalchbr. & Cooke 1880
Er
Family: Eremascaceae Engl. & E. Gilg 1924
Eremascaceae imperfectae C.W. Dodge 1935
Genus: Erikssonia Penz. & Sacc. 1898
Erikssonia carissae Doidge 1948
Genus: Eriomycopsis Speg. 1910
Eriomycopsis asterinae Hansf. 1942 accepted as Atractilina asterinae (Hansf.) Deighton & Piroz., (1972)
Eriomycopsis bomplandi Speg. 1910
Eriomycopsis flagellata Hansf. 1942
Eriomycopsis meliolae Hansf. 1942
Eriomycopsis minima Hansf. 1942 accepted as Rhytidenglerula minima (Hansf.) Arx, (1962)
Eriomycopsis ugandae Hansf. 1942
Genus: Erostella (Sacc.) Sacc. 1906 accepted as Phaeoacremonium W. Gams, Crous & M.J. Wingf., (1996)
Erostella quaternarioides Sacc.*
Family: Erysiphaceae Tul. & C. Tul. 1861
Genus: Erysiphe R. Hedw. ex DC. 1805
Erysiphe aquilegiae DC. 1815
Erysiphe brachystegiae Doidge 1948
Erysiphe cichoracearum DC. 1805
Erysiphe communis Link. (sic) possibly (Wallr.) Schltdl. 1824 accepted as Erysiphe cruciferarum Opiz ex L. Junell, (1967)
Erysiphe cruciferarum Opiz ex L. Junell, (1967) recorded as Erysiphe communis Link. (sic) possibly (Wallr.) Schltdl. 1824
Erysiphe graminis DC. 1815 accepted as Blumeria graminis (DC.) Speer, (1975)
Erysiphe heraclei DC., (1815) recorded as Erysiphe umbelliferarum (Lév.) de Bary 1870,
Erysiphe jatrophae Doidge 1948,
Erysiphe martii Lév. 1851 accepted as Erysiphe trifolii Grev., (1824)
Erysiphe nitida (Wallr.) Rabenh. 1844
Erysiphe pisi DC. 1805
Erysiphe polygoni DC. 1805
Erysiphe trifolii Grev., (1824) recorded as Erysiphe martii Lév. 1851
Erysiphe umbelliferarum (Lév.) de Bary 1870, accepted as Erysiphe heraclei DC., (1815)
Eu
Subclass: Eubasidii*
Genus: EubelonisClem., (1909) accepted as Calycina Nees ex Gray, (1821)
Eubelonis ocoteae Van der Byl 1926
Genus: Eucantharomyces Thaxt. 1895
Eucantharomyces africanus Thaxt. 1900
Genus: Eudarluca Speg. 1908
Eudarluca australis Speg. 1908
Genus: Eudimeriolum Speg. 1912
Eudimeriolum gymnosporiae Hansf. 1946, accepted as Episphaerella gymnosporiae (Hansf.) Arx, (1962)
Genus: Eumitra*
Eumitra implicita Stirt.*
Genus: Eupelte Syd. 1924
Eupelte amicta Syd. 1924
Family: Eurotiaceae Clem. & Shear 1931
Genus: Eurotium Link 1809
Eurotium herbariorum (Weber ex F.H. Wigg.) Link ex Nees 1816, accepted as Aspergillus glaucus (L.) Link, (1809)
Genus: Euryachora Fuckel 1870
Euryachora maculiformis E.E. Nel 1942
Genus: Eutypella (Nitschke) Sacc. 1875
Eutypella acacia Doidge 1941
Eutypella citricola Syd. & P. Syd. 1909
Eutypella doidgeae Syd. 1939
Eutypella lycii Doidge 1941 accepted as Eutypella capensis Rappaz, (1987)
Eutypella macowani Doidge 1941
Eutypella stellulata (Fr.) Sacc. 1882
Ev
Genus: Evernia Ach. 1809 (Lichens)
Evernia chrysophthalma Flotow.*
Evernia flavicans (Sw.) Fr. 1831 accepted as Teloschistes flavicans (Sw.) Norman, (1852)
Evernia flavicans var. dealbata Flot. 1843
Ex
Genus: Exidia Fr. 1822
Exidia auricula-judae (Bull.) Fr. 1822 accepted as Auricularia auricula-judae (Bull.) Quél., (1886)
Exidia caespitosa Lloyd 1915
Exidia duthiei Lloyd 1915
Exidia purpurea-cinerea MacOwan & Kalchbr. (sic)possibly Exidia purpureocinerea MacOwan 1882
Genus: Exoascus Fuckel 1860
Exoascus deformans (Berk.) Fuckel 1870 accepted as Taphrina deformans (Berk.) Tul., (1866)
Family: Exobasidiaceae J. Schröt. 1888
Genus: Exobasidium Woronin 1867
Exobasidium giseckiae Allesch. 1895
Exobasidium hesperidum Maire 1917, [as hesperidium] accepted as Muribasidiospora hesperidum (Maire) Kamat & Rajendren, (1968)
Exobasidium vaccinii (Fuckel) Woronin 1867
Exobasidium vitis (Viala & G. Boyer) Prill. & Delacr. 1894 accepted as Aureobasidium pullulans (de Bary & Löwenthal) G. Arnaud, (1918)
Genus: Exosporium Link 1809
Exosporium celastri Kalchbr. 1880 accepted as Stigmina celastri (Kalchbr.) M.B. Ellis, (1959)
Exosporium palmivorum Sacc. 1898, accepted as Scolecostigmina palmivora (Sacc.) Kamal, (2010)
See also
List of bacteria of South Africa
List of Oomycetes of South Africa
List of slime moulds of South Africa
List of fungi of South Africa
List of fungi of South Africa – A
List of fungi of South Africa – B
List of fungi of South Africa – C
List of fungi of South Africa – D
List of fungi of South Africa – E
List of fungi of South Africa – F
List of fungi of South Africa – G
List of fungi of South Africa – H
List of fungi of South Africa – I
List of fungi of South Africa – J
List of fungi of South Africa – K
List of fungi of South Africa – L
List of fungi of South Africa – M
List of fungi of South Africa – N
List of fungi of South Africa – O
List of fungi of South Africa – P
List of fungi of South Africa – Q
List of fungi of South Africa – R
List of fungi of South Africa – S
List of fungi of South Africa – T
List of fungi of South Africa – U
List of fungi of South Africa – V
List of fungi of South Africa – W
List of fungi of South Africa – X
List of fungi of South Africa – Y
List of fungi of South Africa – Z
References
Sources
Further reading
South African biodiversity lists
South Africa | List of fungi of South Africa – E | [
"Biology"
] | 4,470 | [
"Fungi",
"Lists of fungi"
] |
69,090,227 | https://en.wikipedia.org/wiki/PhotoStage | PhotoStage Slideshow Producer is a video slideshow creator using photos, videos, and music. It can also be used as an organizational and basic editing tool.
Software
A slideshow can be made by importing the desired photos. The software includes a timeline thumbnail with duration and transition types for each photo. Text tool can be used to add one or two lines of text to the slides.
Whilst using the software, one can add their own recorded narration or soundtrack by accessing the NCH Sound Effect Library. The slideshow file is exportable in fifteen formats.
Reception
The software has been reviewed by Top Ten Reviews, Softonic, and others.
References
Further reading
Presentation software | PhotoStage | [
"Technology"
] | 138 | [
"Computing stubs",
"Software stubs"
] |
69,090,263 | https://en.wikipedia.org/wiki/Smartify | Smartify is a mobile app which can scan artworks and return information about them.
History
Smartify was founded by four friends in 2015. The app was launched at the Royal Academy of Arts in October 2017.
During the COVID-19 pandemic, the app made content available allowing users to browse items in museums digitally.
Operation
The app is available on iOS, Android, and as a web app. Smartify describes itself as "a Shazam for the art world". When an artwork is scanned, Smartify compares it to the artwork in its database. If the artwork is recognised, its name and a description are returned to the user.
The app has been identified as an accessibility aid for visually impaired people who may struggle to see an artwork or text surrounding it, as one can zoom in on a picture of an artwork and read or listen to a description of it.
Jonathan Jones, writing for The Guardian, called the idea that in order to appreciate a work of art one needs to be "spoonfed amazing facts about it ", "erroneous and slightly pathetic".
References
Information retrieval systems
Android (operating system) software
IOS software
Universal Windows Platform apps
2017 software | Smartify | [
"Technology"
] | 239 | [
"Information technology",
"Information retrieval systems"
] |
69,091,137 | https://en.wikipedia.org/wiki/SN%202020jfo | SN 2020jfo was a type II supernova in the Messier 61 galaxy, first observed on 6 May 2020 with an apparent magnitude of 16.01. It was one of the first supernovae for which independent, multi-instrument data was collected before, during, and after the explosion. Large astronomical surveys like Transiting Exoplanet Survey Satellite (TESS) and Pan-STARRS have played a role in data collection before and after these events.
References
Supernova remnants
Supernovae
Astronomical objects discovered in 2020
Virgo (constellation) | SN 2020jfo | [
"Chemistry",
"Astronomy"
] | 113 | [
"Supernovae",
"Astronomical events",
"Virgo (constellation)",
"Constellations",
"Explosions"
] |
69,092,297 | https://en.wikipedia.org/wiki/Ketimine%20Mannich%20reaction | The ketimine Mannich reaction is an asymmetric synthetic technique using differences in starting material to push a Mannich reaction to create an enantiomeric product with steric and electronic effects, through the creation of a ketimine group. Typically, this is done with a reaction with proline or another nitrogen-containing heterocycle, which control chirality with that of the catalyst. This has been theorized to be caused by the restriction of undesired (E)-isomer by preventing the ketone from accessing non-reactive tautomers. Generally, a Mannich reaction is the combination of an amine, a ketone with a β-acidic proton and aldehyde to create a condensed product in a β-addition to the ketone. This occurs through an attack on the ketone with a suitable catalytic-amine unto its electron-starved carbon, from which an imine is created. This then undergoes electrophilic addition with a compound containing an acidic proton (which is an enol). It is theoretically possible for either of the carbonyl-containing molecules to create diastereomers, but with the addition of catalysts which restrict addition as of the enamine creation, it is possible to extract a single product with limited purification steps and in some cases as reported by List et al.; practical one-pot syntheses are possible. The process of selecting a carbonyl-group gives the reaction a direct versus indirect distinction, wherein the latter case represents pre-formed products restricting the reaction's pathway and the other does not. Ketimines selects a reaction group, and circumvent a requirement for indirect pathways.
Theory
It is well-known that Lewis acids and bases can influence carbonyl activity by either protonation of the oxygen or de-protonation of a beta-site to influence electrophilicity at the carbon. In the former case, there is a stabilization effect and priming for a potential leaving group by providing an equilibrium between a formal positive charge and an alcohol group. In either case, the carbon sees enhanced reactivity as the bonds are strained to equalize charge by seeking a nucleophile to which the building charge will equalize into in the subsequent reaction. Potentiation in such reactions is therefore generally driven by how well a material can produce and stabilize a charge gradient through resonance or inductive effects in substituents. The surfaces of acids can catalyze these effects by stabilizing the distortion of the carbonyl's electron cloud, leading to sensitivity in the reaction to acid-base conditions, with acidic conditions typically favoring reaction by enhancing carbonyl leavability.
Mannich reactions are named after their pioneer, Carl Mannich. After the discovery of Mannich reaction in 1912, he found that combination of a ketone, aldehyde and amine consistently produced an addition of the aldehyde unto the site originally containing an acidic β-proton in the ketone. He theorized the mechanism to be one of mixed-aldol; featuring the dehydration of an alcohol and Michael-Addition of the complex. The reaction suffered from a lack of specificity, and this problem persisted until 1997, in which an asymmetrical method was discovered independently by several researchers. Kobayashi et al. used Brønsted-acid to demonstrate that the organic reaction could occur in an aqueous medium, and also found an enantiomeric excess of nearly 55%. It was hypothesized that one of the reactants must be using the acid surface to change its electronic structure since otherwise the mixture would be immiscible, though the study used chiral Lewis acid as catalyst. Prior, Hajos et al. demonstrated a method by which L-proline could be used in an aldol-cyclization.
Subsequent studies have focused on improving the catalyst or materials through substituent effects, from which controls using sterics or restriction of charge sites are expected to improve catalytic yields. Alternatives to the catalyst are not readily explored due to the ubiquity of L-proline, its low cost, and its high selectivity; cementing its proliferation as a catalytic standard. L-proline restricted reactions through its five-membered ring which favours the addition of another reactant in a fixed direction. List et al. theorize in their study that this restriction is primarily in the carboxylic-acid group next to the enamine attachment, which can stabilize the imine product. List also expands upon the role of the imine by listing its ratio with the aldehyde to be 1 using 1H-NMR methods, indicating that the Michael Addition is rate-determining and not the proline-complexation or, obviously, aldehyde activation. This is further confirmed in a Hammett study on para-substituted aromatic aldehydes, in which List confirmed positive correlation between withdrawing effect and increasing imine reactivity, a sign that Michael addition had to be happening with the former aldehyde as an electrophile.
Substituent studies
Substituent studies have focused on increasing or decreasing steric or electronic influences on material to favor product. In 2012, the first non-aromatic ketiminoester was produced with the capability of reduction into either syn- or anti- lactones with NaBH4 reduction. Kano et al. demonstrated a 20:1 excess of desired product, electrophilic enhancement of the ketone by different flanking esters.
Endocyclic ketimines without electron-withdrawing substituents
BINOL phosphoric acid-catalyzed Mannich reaction (2019)
Reddy and coworkers proposed the method to produce endocyclic N-acyl ketimines from a stable precursor, 3-aryl-3-hydroxyisoindolin-1-ones in 2019. The reaction yields a high stereoselectivity under high temperature as the adjacent quaternary and stereogenic centers creating chirality. Meanwhile, if 3-hydroxy-3-pentylisoindoline-1-one is used, 95% enamide would be generated instead of Mannich product under the same mechanism.
Proline-catalyzed direct asymmetric Mannich reaction of 3-substituted-2H-1,4-benzoxazines (2013)
In 2013, Wang and coworkers studied using 3,4-dihydro-2H-1,4-benzoxazines to produce N-heterocyclic products. This reaction was the first catalytic asymmetric Mannich reaction of 3,4-dihydro-2H-1,4-benzoxazines. The aromatic ring strain in 3,4-dihydro-2H-1,4-benzoxazines helps increase reactivity of the C=N double bond and gives the considerable yield with no electron withdrawing substituents. Similar mechanism also occurred in the reaction catalyzed by wheat germ lipase in 2016 provided by Guan, He and coworkers.
Copper-catalyzed asymmetric Mannich reaction of 2H-azirines with β-keto amides (2018)
In 2018, Lin, Feng, and coworkers developed the first copper-catalyzed catalytic enantioselective Mannich reaction using 2H-azirines and β-ketoamides. The racemic 2H-azirines was first applied and one enantiomer of the 2H-azirine would react with chiral Cu-enolated complex to help overcome its three neighbouring stereogenic centers and gave proper products.
Copper(I)-catalyzed asymmetric decarboxylative Mannich reaction of 2H-azirines (2019)
In 2019, Yin and coworkers used 2H-azirines as an electrophile and a base at the same time to deprotonate cyanoacetic acid and thus a further decarboxylation could proceed. Proton transfer strategy was also discussed since the protonated 2H-azirine obtains high electrophilicity while nonprotonated ones does not even react with exact same environment. Various substituents on both nucleophile and electrophile gave high enantiomer-enriched yields of azirines.
Zn-ProPhenol catalyzed asymmetric Mannich reaction of 2H-azirines with alkynyl cycloalkyl ketones (2020)
In 2020, Trost and coworker proposed a Mannich reaction of 2H-aziridines with alkylnyl cycloalkyl ketones under a bimetallic Zn-ProPhenol complex as the catalyst. The bimetallic Zn-ProPhenol complex employed in the reaction to activate both nucleophile and electrophile since the compound obtains a Bronsted basic site and a Lewis acidic group at chiral center at the same time. The hydrogen bonding between N from aziridine and H from carbonyl group might also contribute chirality centred at nitrogen atom. In this case, N-H bond acetylation product was also generated from the reaction.
Chiral phosphoric acid-catalyzed Mukaiyama–Mannich reaction of endocyclic N-acyl ketimines (2020)
In 2020, Zhang, Ma, and coworkers used 3-hydroxyisoindolin-1-ones to produce endocyclic N-acyl ketimines by chiral phosphoric acid-catalyzed Mukaiyama–Mannich reaction. Difluorinated silyl enol ethers are involved to produce enantioenriched fluoroalkyl-functionalized isoindolones first. Through the reaction under different conditions, two features were discovered. Firstly, hexafluoroisopropyl alcohol could enhance the reactivity and enantioselectivity. Secondly, reaction is better catalyzed by catalyst with trifluoromethyl group chiral barriers.
Isatin-derived ketimines
Isatin-derived ketimine commonly undergoes catalytic asymmetric Mannich reaction to generate 3-substituted-3-aminooxindoles. The structure could be found in various natural or biological molecules, and such reaction could lead to enantio-enriched products. Moreover, the isatin-derived ketimines are comparatively reactive as an electrophile and thus was commonly used in various methods or reactions.
Morimoto, Ohshima, and coworkers applied decarboxylative Mannich reaction on N-unprotected isatin-derived ketimines in 2018. The researchers applied an enantio-enriched chiral oxindoles on the 3-positions with primary amines. In this case, substrates with less substituted groups are more likely to undergo Mannich reactions with higher yield. Also, this routine allows a great range of ketoacids to react with ketimines before decarboxylation and generate Mannich products.
Wolf and coworkers further developed a copper-catalyzed stereo-divergent Mannich reaction in 2020. Isatin-derived ketimines first react with α-fluoro-α-arylnitrile and result in a chiral cuprous keteniminate complex. Then, BTMG would act as a nucleophile and the stereoselectivity would be determined by the chosen of chiral ligands. From experiment, Segphos–copper complex generated anti diastereomers while Taniaphos complex results in syn diastereomers.
Feng and coworkers used chiral N,N' -dioxide/Zn(II) complexes to catalyze silyl enol ethers and ketimines in 2019. The reaction started with an α-alkenyl addition of silyl enol ethers. Dioxide (compound 21 and 22 in scheme 20) was proved to the best reaction condition for a wide range of isatin-derived ketimines to generate great yield of products with high stereoselectivity. Pyrazolinone-derived ketimines are also found to be suitable substates. The mechanism demonstrates that Mukaiyama–Mannich addition intermediates produced β-amino silyl enol ethers as product.
Acyclic ketimines with electron-withdrawing groups and/or alkynes
Esters, perfluorinated alkyl, or alkyne groups are good electrophiles, that can be used to form ketimine enolate with different nucleophiles. However, subtle differences in ketimine structures can significantly affect stereoselectivities and yields. Nevertheless, many medicinally and synthetically significant chiral structure can be created by creative design on modified ketimines.
In 2016, a novel direct asymmetric Mannich reaction of ketiminoesters with thionolactones were proposed by Terada et al. by using bis(guanidino)iminophosphorane as a chiral organosuperbase catalyst. (scheme 21) Comparing to thionolactones as an appropriate nucleophile, lactone is not acidic enough to be enolized by base catalyst, which makes lactone unable to act as a nucleophile. For electrophiles, having proper substituents on benzoyl protecting group can improve yields and diastereoselectivity. For instance, comparing to trifluromethyl group on ketiminoester, methoxy substituents gives much lower yield and selectivity.
In 2016, direct asymmetric catalytic Mannich reaction of an alpha, beta-unsaturated gamma-butyrolactam with ketiminoesters was proposed by Kumagai el al. using soft Lewis acid/hard Brønsted base cooperative catalysis. (scheme 22) As a result, alpha-addition products were synthesized from alpha,beta-unsaturated gamma-butyrolactams onto ketimines through asymmetric catalysis, which is a novel catalytic asymmetric reaction. The corresponding phosphinoyl protected ketiminoester did not react without the cooperative catalysis by the soft Lewis acid / hard Bronsted base, which means the interaction between copper catalyst (as soft Lewis acid) and thiophosphinoyl protecting group of ketimines (as soft Lewis base) is significant for this successful Mannich reaction.
In 2017, a direct enantioselective Mannich reaction with an N-unprotected trifluoromethyl ketiminoester was proposed by Morimoto et al. (scheme 23) The unprotected N-H ketimines alleviate problems caused by E/Z isomerism in the asymmetric catalytic reactions, although they generally have lower stability. Morimoto et al. showed that the unprotected N-H ketimines are able to react with malonates, esters, oxindoles, and cyclic beta-keto-nitiles under different temperatures to give products whose diastereoselectivities can be controlled under asymmetric catalysis.
In 2018, Zn-ProPhenol was used to catalyze asymmetric Mannich reaction of butenolides with perfluoroalkyl alkynyl ketimines, which is proposed by Trost et al. (scheme 24) Several features about this reaction were reported:
1. Ketimines are more electrophilic, resulted by fluorinated groups
2. Alkyne group has less steric effect, and its high s character makes ketimines more electrophilic
3. Steric difference between alkynyl and perfluoroalkyl groups would give ketimines in a single diastereomeric form, which is critical for high stereoselectivities.
The reaction is broad in scope, which allows further contribution in medicinal field and synthetic chemistry.
Chiral amines like amino acid derivatives can catalyze many enantioselective transformations, although enantiomers of amino acids are hard to access sometimes. In 2019, Lan et al. proposed a strategy to apply their chiral amine catalyst with minimal modification to the Mannich reaction of alkynyl ketiminoesters. (scheme 25) Their application shows that catalyst 26 and MeCN can be replaced by 28 and dichloroethane for many alkynyl trifluoromethyl-, pyrazolinone-derived-, and isatin-derived ketimines to give the same stereoselectivities and yields.
It is hard to control E/Z selectivity for ketimines having two structurally similar substituents, which makes such kind of ketimines merely used in asymmetric catalysis field comparing to ketimines that have single diastereomeric form. In 2021, Kano et al. proposed method to use alkynyl ketimines as synthetic equivalents of dialkyl ketimines, and dialkyl ketimes are a typical example of isomeric ketimine mixtures. The alkynyl groups can be reduced by hydrogenation back to corresponding alkyl groups. Moreover, a single diastereomeric alkynyl alkyl N-protected ketimines can be obtained by using steric difference between alkyl and alkynyl group, which makes them be stereoselectively controlled by chiral catalyst to give asymmetric Mannich product. Additionally, small steric hindrance and high s character of alkynyl group result in its high nucleophilicity, making alkynyl-substituted ketimines more reactive than alkyl counterparts. Even though additional step of hydrogenation is needed, the advantages provided by alkynyl group are still impressive. To solve the problem that a single diastereomeric form of N-Boc alkyl alkynyl ketimines are difficult to access, Kano et al. proposed a synthesis to form these ketimines (reaction 1 and 2), followed by operating chiral amine-catalyzed Mannich reactions (reaction 3). (scheme 26) The chiral amine catalyzed the asymmetric Mannich reaction of aldehyde and (Z)-alkyl alkynyl ketimines. The method they used is stereodivergent, in which the phenylcyclopropane amine 29 gives syn products, and the proline catalyst gives anti product. After the hydrogenation step, they successfully obtained chiral amines substituted with two similar alkyl groups, which is hard to obtained in a single enantiomeric compound.
Applications
Ketimine Mannich catalysis has been identified as a synthetic tool for primary alcohols. A useful path to dihydroquinazolinone, a precursor to drugs with anti-viral and cardiovascular benefits, was also found by Liu et Al. using N-Heterocyclic carbene-catalyzation [4+2] annulation of β-methyl enals.
References
Organic reactions | Ketimine Mannich reaction | [
"Chemistry"
] | 4,038 | [
"Organic reactions"
] |
69,092,857 | https://en.wikipedia.org/wiki/Plasmonic%20catalysis | In chemistry, plasmonic catalysis is a type of catalysis that uses plasmons to increase the rate of a chemical reaction. A plasmonic catalyst is made up of a metal nanoparticle surface (usually gold, silver, or a combination of the two) which generates localized surface plasmon resonances (LSPRs) when excited by light. These plasmon oscillations create an electron-rich region near the surface of the nanoparticle, which can be used to excite the electrons of nearby molecules.
Similar to photocatalysts, plasmonic catalysts can transfer their excitation energy to reactant molecules through resonance energy transfer (RET). Unlike photocatalysts, plasmonic catalysts can also excite reactant molecules by the release of hot carrier electrons which have a high enough energy to completely dissociate from the metal surface. The energy of these hot carrier electrons can be altered by changing the wavelength of light striking the surface and the size of the nanoparticles present, which allows the hot electrons to take on the excitation state needed to catalyze multiple different reactions.
Although the field of plasmonic catalysis is still in its infancy, there are clear advantages to utilizing a plasmon-active surface over traditional photocatalysts. Their ability to utilize energy from near-infrared, visible, and ultraviolet light gives plasmon surfaces higher light-capturing efficiency than photocatalysts, which can only utilize ultraviolet light, and the larger possible energy range of the electromagnetic field and emitted electrons make the resulting catalytic effects both broadly applicable and highly tunable.
Mechanism
Broadly speaking, plasmonic catalysis increases the reaction rate through two major pathways. The first of these is through the generation of an electromagnetic field during plasmon oscillations. This field lowers the activation energy of the reaction through excitation of the reactants electrons by resonance energy transfer. It can also provide localized transition state stabilization, further increasing the rate of reaction.
The second pathway is through the generation of hot carrier electron/phonon pairs. When a plasmon is generated, some electrons may have the energy to break completely free of the nanoparticle's electron shells. These highly excited electrons can then excite reactant electrons in the highest occupied molecular orbital or fill the lowest unoccupied molecular orbital, raising the energy of the molecule and allowing for a lower energy transition state. In most cases, these hot electrons do not find a reactant molecule to excite and instead fill the phonon and return to a ground state energy. The excess energy from the process is released as thermal energy, creating a localized temperature increase which can also increase the rate of reaction.
Examples
The photocatalytic electrolysis of water has been shown to be up to 66 times more efficient when using a gold nanoparticle surface.
The rate of demethylation of methylene blue by a Titanium dioxide photocatalyst has been increased sevenfold in the presence of silver nanoparticles.
The plasmonically catalyzed oxidation of several common gases- including carbon monoxide, ammonia, and oxygen- can occur at far lower temperatures than are normally required due to the strong catalytic effects of plasmonic surfaces when excited by visible light.
Recently hybrid plasmonic nanomaterials started being explored for organic synthesis or the production of solar fuels.
References
Nanotechnology
Catalysis | Plasmonic catalysis | [
"Chemistry",
"Materials_science",
"Engineering"
] | 722 | [
"Catalysis",
"Nanotechnology",
"Chemical kinetics",
"Materials science"
] |
69,093,394 | https://en.wikipedia.org/wiki/Ford%20Indy%20V8%20engine | The Ford Indy V8 engine is a V-8 engine, initially specially designed by Ford for Indy car racing, from 1963 onwards, winning the Indy 500 four times as Ford, plus once as Foyt in 1977.
As naturally-aspirated DOHC version, it won the 1965 Indianapolis 500 as well as in 1966 and 1967. When a turbocharged Offenhauser took the win in 1968, Ford also reduced capacity and added a turbocharger, winning the 1969 Indianapolis 500. Ford ended the works campaign after 1971, handing over the design to AJ Foyt who continued until 1978, winning the Indy 500 in 1977.
Concurrently, in England, Ford had since 1965 sponsored the successful Cosworth DFV Formula One engine, a more compact DOHC V8, designed for 3.0 litre. For the 1976 USAC Championship Car season, Ford returned to Indy car racing with the turbocharged 2.65 litre Ford-sponsored Cosworth DFX engine.
1963 engine
IndyCars with Ford engines first competed in 1935 using a production-based Ford flathead V8 engine in the Miller-Ford racer.
With the Offenhauser 4cyl 4.4 litre engine mounted in front-engine roadsters dominating Indy 500 races since the 1930s, and with a British Invasion of successful nimble rear-mid-engine Formula One single seater coming to the US, like two time F1 World Champion Jack Brabham to the 1961 Indianapolis 500, it was time for a change. Mickey Thompson entered three rear-engine cars in the 1962 Indianapolis 500, but with a Buick V8 that lacked power. Driver Dan Gurney then arranged that European chassis makers Team Lotus, who would win their first F1 World Championship in 1963, would build the Lotus 29 for the 1963 Indianapolis 500, with Ford supplying a suitable engine. With the intakes as usual in the V, the 4195 cc (255ci) pushrod Ford V8 with Weber carburettors produced 376 bhp (280 kW) through a Colotti T.37 gearbox. Eventually, Jim Clark finished second, and Dan Gurney finished seventh. Clark went on to win the 1963 Tony Bettenhausen 200, proving the design was competitive.
1964-1967 DOHC engine
To gain power for 1964, double overhead camshafts (DOHC) were installed in the Lotus 34, in reverse manner, with the exhausts in the V, intake trumpets at the sides. This four-cam 4195 cc (255ci) DOHC Ford V8 with Hilborn fuel injection produced 425 bhp (317 kW), through a ZF 2DS20 gearbox. Clark qualified on pole for the 1964 Indianapolis 500, but when the Dunlop tyres caused Clark to crash, Gurney was retired. The team switched to Firestone rubber.
In 1965 A.J. Foyt won three USAC races in a Lotus 34 on his way to second in that years championship, while Parnelli Jones finished second at 1965 Indianapolis 500 behind Jim Clark's improved Lotus 38. It was the first win for a rear-mid engined car, the first for Ford, and the first for a foreigner in many decades.
The Ford DOHC engines were available for other teams. Graham Hill won the 1966 Indianapolis 500 with a Lola 90 chassis, and A. J. Foyt in 1967 in a Coyote 67 chassis.
1968-1971 Turbo
By 1968, Offenhauser was using turbo engines which had more power, winning the 1968 Indianapolis 500.
Thus, a smaller but Garrett turbocharged Ford engine was introduced in 1968, and gave Mario Andretti the win in his Brawner Hawk chassis at the 1969 Indianapolis 500. This engine was used throughout the 1969 and 1970 seasons, until 1971 (their last season), after which Ford pulled-out and withdrew from the series for 1972.
1969 Lotus 64 turbo engine
Because the previous Lotus 56 AWD had a gas turbine engine, which was banned, Lotus had to use a new engine for the 1969 Indianapolis 500. The Lotus 64 project was funded by Ford who supplied a V8 turbo engine, and by STP. The 4 wheel drive was retained, thus the biggest difference was the new engine; a 2.65-liter turbocharged Ford engine, making more than 700 horsepower. As the drivetrain overheated and Mario Andretti crashed the STP car in practise, also the cars of Graham Hill and Jochen Rindt were retired before the Race.
1966 F1 Ford 406 engine
The Ford 406 was a Formula One engine, and was essentially a downsized variant of the Ford Indy V8 DOHC engine, commissioned by Bruce McLaren who had been involved since 1964 with the Ford GT40 program, winning the 1966 Le Mans 24h.
Made by third parties prior to the introduction of the highly successful Ford-sponsored Cosworth DFV engine in 1967, it was used in the McLaren M2B Formula One car for three races in the 1966 Formula One season.
An oil leaked ended the first race in Monaco, and the team switched to other engines. In the last two heats in North America, the Ford V8 was again used, with one finish for points.
1973-1978 Foyt engine
Ford Motor Company pulled its factory support out of Indy/Championship car racing after the 1972 USAC season. A. J. Foyt obtained the rights to Ford's turbocharged DOHC V-8 Indy engine, and it was subsequently rebadged and rebranded as the Foyt V-8 engine.
The Foyt team further developed the powerplant, and ran the Foyt V-8 engine from 1973 to 1978. A handful of other teams bought and ran Foyt V-8 engines during that timeframe as well. A. J. Foyt himself won the 1977 Indianapolis 500 in his Coyote chassis and the Foyt-badged engine.
Applications
Brawner Hawk
Coyote 67
Coyote 68
Coyote/Kuzma
Coyote 70
Coyote 71
Lola T80
Lola T90/T92
Lola T150/T153
Lola T270/T272
Lotus 29
Lotus 34
Lotus 38
Lotus 42
Lotus 64
McNamara T-500
McNamara T-501
References
Engines by model
Ford engines
IndyCar Series
V8 engines
Gasoline engines by model | Ford Indy V8 engine | [
"Technology"
] | 1,257 | [
"Engines",
"Engines by model"
] |
69,094,346 | https://en.wikipedia.org/wiki/Firazorexton | Firazorexton (; development code TAK-994) is an experimental orexin 2 (OX2) receptor agonist first described in a 2019 patent filed by Takeda Pharmaceutical Company.
Firazorexton was studied by Takeda for the treatment of narcolepsy. It is a small-molecule and orally active compound and acts as a highly selective agonist of the orexin receptor 2 (OX2) with >700-fold selectivity over the orexin receptor 1 (OX1). Firazorexton is related to danavorexton (TAK-925). The compound reached phase 2 clinical trials for narcolepsy. However, clinical development was discontinued in October 2021 for safety reasons.
See also
Orexin receptor § Agonists
List of investigational sleep drugs § Orexin receptor agonists
References
Abandoned drugs
Biphenyls
Fluoroarenes
Orexin receptor agonists
Pyrrolidines
Sulfonamides
Tertiary alcohols
Wakefulness-promoting agents | Firazorexton | [
"Chemistry"
] | 207 | [
"Drug safety",
"Abandoned drugs"
] |
69,094,489 | https://en.wikipedia.org/wiki/Fakhr%20al-Din%20al-Akhlati | Fakhr al-Din al-Akhlati (Kurdish: Fexredînê Exlatî, Fakhr al-Din al-Kurdi al-Akhlati; ; flourished ), was a Kurdish and Islamic astronomer from Anatolia, who worked at the Maragha observatory. He was one of the first elites that the Persian polymath Nasir al-Din al-Tusi recruited to work in there. Al-Akhlati's life was in a period contemporaneous with the fall of Baghdad at the hands of the Mongols in 1258.
References
Sources
Further reading
Astronomers of the medieval Islamic world
Kurdish astronomers
13th-century Kurdish people | Fakhr al-Din al-Akhlati | [
"Astronomy"
] | 138 | [
"Astronomers",
"Astronomer stubs",
"Kurdish astronomers",
"Astronomy stubs"
] |
69,094,557 | https://en.wikipedia.org/wiki/Tassili%20Mushroom%20Figure | The popularly called Tassili mushroom figures are Neolithic petroglyphs and cave paintings discovered in Tassili n'Ajjer, Algeria, which contain features resembling mushrooms. Hypothesized to date back to 7000–5000 BC, they are considered by some researchers to be figures that have shamanic connotations and one of the strongest pieces of evidence for ethnomycological data. It is possibly the oldest example of rock art used to claim the ritual use of fungi in prehistory, with Tassili being the first site that likely may contain representations of the genus Psilocybe (the second example is at the Spanish archaeological site of Selva Pascuala). However, interpretations of Tassili's drawings are disputed and it is unknown whether they actually represent mushrooms or specific natural or cultural elements.
Discovery
The discovery of prehistoric rock art at the Tassili n'Ajjer archaeological site occurred throughout the 1910s, 1930s, and into the 1960s. The popularizer of these figures in particular was Henri Lhote (in publications of 1968, 1973), who associated them with specialized shamanic ceremonies, on the hypothesis that their caves served as sacred sanctuaries. But they had already been discovered by local Tuaregs and French Lieutenant Charles Brenans, who documented some of the paintings between 1933 and 1938. Lhote was a member of Brenans' team and gathered his notes. Afterwards, Lhote returned to the site on new expeditions, between 1956 and 1962; Jean-Dominique Lajoux was a photographer for Lhote's Sahara expeditions. Lhote's descriptive approach has been criticized for reducing them to a religious interpretation and for popularizing terms such as "Martians" or "Great Gods" among archaeologists to refer to the round-headed figures at Tassili.
The mushroom-like silhouette type has been variously interpreted by researchers as an arrowhead, oar (according to ethnographer Fabrizio Mori, 1975), a vegetable (probably a flower, according to Henri Lhote), or an undefined enigmatic symbol. In one of the panels, several masked anthropomorphic figures appear to be dancing and holding mushrooms. A publication by the US Forest Service acknowledged that "The oldest known petroglyph depicting the use of psychoactive mushrooms comes from the rock shelters at Tassili n'Ajjer" and that "It is postulated that the mushrooms depicted on the “mushroom shaman” are Psilocybe mushrooms.". Other drawings with mushroom-shaped features appear on petroglyphs in the region.
The ethnobotanist Giorgio Samorini characterized them as probably the oldest physical evidence of entheomycological practices (the use of psychedelic mushrooms), reflecting altered states of consciousness and dance rituals, according to the posture of certain figures. Mycologist Gastón Guzmán considers that the mushrooms in the picture are of the PsiIocybe mairei species, but they also resemble other African mushrooms from the region, such as P. cubensis, P. aquamarina and P. natalensis.
However, there are recent studies by scholars of rock art who question the shamanistic paradigm and the supposed interpretations that certain characteristics of the images would illustrate pre-existing anthropological categories, which assumes a universal application for different cultures. Ethnomycologist Brian Akers (PhD) says it's not certain whether the Tassili figures are the oldest to represent mushrooms, nor as to dating and scientific peer review, nor as to style, which is far from naturalistic and can be abstract. He claims that Tassili's arts have become iconic 1990s psychedelia in popular culture and have been the subject of fringe theories such as the "Ancient Psychonaut Theory" and the Ancient Astronaut Theory.
See also
Mushrooms in art
References
Prehistoric art
Rock art in Africa
Archaeology of Algeria
Entheogens
Fungi and humans | Tassili Mushroom Figure | [
"Biology"
] | 801 | [
"Fungi and humans",
"Fungi",
"Humans and other species"
] |
62,446,290 | https://en.wikipedia.org/wiki/Guignardia%20festiva | Guignardia festiva is a plant pathogen that has been recorded on Sumbaviopsis albicans.
References
Fungal plant pathogens and diseases
Botryosphaeriales
Fungi described in 1912
Taxa named by Hans Sydow
Taxa named by Paul Sydow
Fungus species | Guignardia festiva | [
"Biology"
] | 58 | [
"Fungi",
"Fungus species"
] |
62,448,004 | https://en.wikipedia.org/wiki/Disappearing%20polymorph | In materials science, a disappearing polymorph is a form of a crystal structure that is suddenly unable to be produced, instead transforming into a different crystal structure with the same chemical composition (a polymorph) during nucleation. Sometimes the resulting transformation is extremely hard or impractical to reverse, because the new polymorph may be more stable. It is hypothesized that contact with a single microscopic seed crystal of the new polymorph can be enough to start a chain reaction causing the transformation of a much larger mass of material. Widespread contamination with such microscopic seed crystals may lead to the impression that the original polymorph has "disappeared". In a few cases such as progesterone and paroxetine hydrochloride, the disappearance is global, and it is suspected that it is because earth's atmosphere is permeated with tiny seed crystals. It is believed that seeds as small as a few million molecules (about grams) is sufficient for converting one morph to another, making unwanted disappearance of morphs particularly difficult to prevent.
This is of concern to the pharmaceutical industry, where disappearing polymorphs can ruin the effectiveness of their products and make it impossible to manufacture the original product if there is any contamination. There have been cases in which a laboratory that attempted to reproduce crystals of a particular structure instead grew not the original but a new crystal structure. The drug paroxetine was subject to a lawsuit that hinged on such a pair of polymorphs, and multiple life-saving drugs, such as ritonavir, have been recalled due to unexpected polymorphism. Although it may seem like a so-called disappearing polymorph has disappeared for good, it is believed that it is always possible in principle to reconstruct the original polymorph, though doing so may be impractically difficult. Disappearing polymorphs are generally metastable forms that are replaced by more stable forms.
It is hypothesized that "unintentional seeding" may also be responsible for the phenomenon in which it often becomes easier to crystallize synthetic compounds over time.
Thermodynamics
Disappearing polymorphs occur when there are two morphs of a substance, and one morph has lower Gibbs free energy, but is kinetically slower to form. Thus, when the crystal is first formed, the kinetically faster morph occurs first. Eventually, by accident or catalysis, the other morph occurs, which can then serve as seed crystal. More abstractly stated, disappearing polymorphs are morphs that are kinetically stable but not thermodynamically stable.
Pharmaceutical and legal impact
In the United States, the first company to develop a drug ("pioneer") must demonstrate the drug is safe and effective by extensive and expensive trials. After that, there would be a period of exclusive rights to sell the drug, after which other companies ("generics") can market the same drug as a generic chemical under the Abbreviated New Drug Application. The pioneer companies often attempt to evergreen the patent drug by many methods. Since the appearance of generics can decrease the revenue rate of patented drugs by as much as 80%, this is very profitable.
When disappearing polymorphs are involved, it is sometimes true that the pioneer company first discovered and patented polymorph A, then polymorph B, but polymorph A inevitably converts to polymorph B when seeded with microscopic amounts of B. This then means that later companies, even if they follow all the steps specified by the pioneering patent, end up with a polymorph B. Since with disappearing polymorphism, it is practically impossible for anyone to produce the original drug without it turning into the new one, producers are effectively barred from selling generics until the patent for the new polymorph has run out. Alternatively, they may try to argue that a new polymorph needs to undergo the same trials as new drugs, potentially delaying release of a generic for years.
Case studies
Paroxetine hydrochloride
Paroxetine hydrochloride was developed in the 1970s by scientists at Ferrosan and patented as US4007196A in 1976. Ferrosan licensed this patent to the Beecham Group, which later merged into GSK (GlaxoSmithKline at the time).
The Paroxetine developed at that time was paroxetine anhydrate, which is a chalky powder that was hygroscopic. This made it difficult to handle. In late 1984, while scaling up the production of Paroxetine, a new crystal form (hemihydrate) suddenly appeared at two Beecham sites in the UK within a few weeks of each other. In the presence of water or humidity, mere contact with hemihydrate converts anhydrate into hemihydrate.
Alan Curzons, working for GSK, wrote down the "Paroxetine Polymorphism" memorandum on May 29, 1985, a memorandum vital to later litigations.
When the patent for paroxetine anhydrate (the "original" polymorph) ran out, other companies wanted to make generic antidepressants using the chemical. The only problem was that by the time other companies began manufacturing, Earth's atmosphere was already seeded with microscopic quantities of paroxetine hemihydrate from GSK's manufacturing plants, which meant that anyone trying to manufacture the original polymorph would find it transformed into the still-patented version, which GSK refused to give manufacturing rights for. Thus, GSK sued the Canadian generic pharmaceutical company Apotex (SmithKline Beecham Corp. v Apotex Corp) for patent infringement by producing quantities of the newer paroxetine polymorph in their generic pills, asking for their products to be blocked from entering the market.
GSK claimed that the anhydrate "inevitably" converts to hemihydrate due to the presence of seeds. Apotex rejected the seeding theory as "junk science", and "alchemy". Both the District Court and the Federal Circuit Court accepted the seeding theory of GSK, but nevertheless both judged in favor of Apotex. The District Court judged that Apotex was not responsible for unintentional presence of seeding in facility. The Federal Circuit Court invalidated the newer patent concerning the hemihydrates, on the argument of prior public use from the clinical trials.
Later research showed that the "anhydrate" was in fact a nonstoichiometric hydrate that rapidly dehydrates and rehydrates. The hemihydrate form is more stable due to a higher number of hydrogen bonds.
Paroxetine mesylate
In order to avoid patents on paroxetine hydrochloride, some companies developed alternative salts of paroxetine. In the mid-1990s SmithKline Beecham (now a part of GSK) and Synthon independently developed paroxetine mesylate. They obtained two separate patents.
Subsequently, all attempts to produce Synthon's version of paroxetine mesylate ended up with Beecham's version. There were two possibilities: either Synthon's version is a disappearing polymorph, or Synthon's patent application contained erroneous data. Many litigations later, there was no legal consensus on which possibility was correct.
Ritonavir
Released to the public in 1996, ritonavir is an antiretroviral medication used to help treat HIV/AIDS. It has been listed on the World Health Organization's List of Essential Medicines. The original medication was manufactured in the form of semisolid gel capsules, based on the only known crystal form of the drug ("Form I"). In 1998, however, a second crystal form ("Form II") was unexpectedly discovered. It had significantly lower solubility and was not medically effective.
Form II was of sufficiently lower energy that it became impossible to produce Form I in any laboratory where Form II was introduced, even indirectly. Scientists who had been exposed to Form II in the past seemingly contaminated entire manufacturing plants by their presence, probably because they carried over microscopic seed crystals of the new polymorph. The drug was temporarily recalled from the market. Tens of thousands of AIDS patients went without medication for their condition until ritonavir was reformulated, approved, and re-released to the market in 1999. It is estimated that Abbott, the company which produced ritonavir under the brand name Norvir, lost over $250 million USD as a result of the incident.
It was a serious public relations problem for Abbott, so the company held interviews and press conferences, at which senior Abbot officials answered questions. The transcripts are archived at .
A later study found 3 additional morphs: a metastable polymorph, a trihydrate, and a formamide solvate.
Rotigotine
Rotigotine (sold under the brand name Neupro among others) is a dopamine agonist indicated for the treatment of Parkinson's disease (PD) and restless legs syndrome (RLS). In 2007, the Neupro patch was approved by the Food and Drug Administration (FDA) as the first transdermal patch treatment of Parkinson's disease in the United States. The drug had been established in 1980, and no prior polymorphism had been observed. In 2008, a more stable polymorph unexpectedly emerged, which was described as resembling "snow-like crystals". The new polymorph did not display any observable reduction in efficacy, but nonetheless, Schwarz Pharma recalled all Neupro patches in the United States and some in Europe. Those with remaining patches in Europe were told to refrigerate their stock, since refrigeration seemed to reduce crystallization rates. The patch was reformulated in 2012, as per FDA recommendations, and was reintroduced in the United States without requiring refrigeration.
Progesterone
Progesterone is a naturally occurring steroid hormone and is used in hormone therapy and birth control pills, among other applications. There are two known forms of naturally-occurring progesterone (or nat‐progesterone), and other synthetic polymorphs of the hormone have also been created and studied.
Early scientists reported being able to crystallize both forms of nat‐progesterone, and they could convert form 2 into form 1 (which is more thermodynamically stable and melts at a different temperature). When later scientists tried to crystallize form 2 from pure materials, they could not. Attempts to replicate older instructions (and variations on those instructions) for crystallization of form 2 invariably produced form 1 instead, sometimes even leading to crystals of exceptional purity but still of form 1. Researchers have tentatively suggested that form 2 became gradually harder to produce around 1975, based on a review of production difficulties documented or alluded to in existing literature.
Form 2 was eventually successfully synthesized by using pregnenolone, a structurally similar compound, as an additive in the crystallization process. The additive seemed to reverse the order of stability of the polymorphs. Multiple theories were proposed for why earlier research was able to produce form 2 from "pure" ingredients, ranging from the possibility that the early researchers were unintentionally working with impure materials to the possibility that seed crystals of form 1 had become more common in the atmosphere of laboratories since the 1970s.
Beta-melibiose
Pfanstiehl Chemical Company in Waukegan, Illinois, was known for isolating and purifying natural substances, including melibiose. The final step of purifying melibiose was to crystallize it. However, one day, all new melibiose crystals appeared in a different morph. The old morph was called beta-melibiose and the new morph, alpha-melibiose. The chemists theorized that tiny traces of the alpha morph in the air or on the lab equipment could be causing this change, but they never found out where the contamination was coming from. Ultimately, the company gave up. However, they suggested that if the process were attempted in a different location, where there was absolutely no trace of alpha morph, it might still be possible to successfully crystallize the beta morph.
As of 1995, this issue might still exist. According to a survey of catalogs from various chemical companies including Merck, Fluka, BDH, Aldrich, and Sigma, only the alpha-melibiose was available.
Beta-melibiose is in fact an epimer of alpha-melibiose. However, since when in solution, alpha- and beta-melibiose rapidly convert to each other, this may still be productively considered a case of crystal polymorphism.
Xylitol
Xylitol, a type of sugar alcohol, was first synthesized from beech wood chips in September 1890 in the form of syrups, but no one reported its crystal forms for 50 years. It has two different crystal morphs. One is a metastable, moisture-absorbing form that melts at 61 °C, and the other is a more stable form that melts at 94 °C. Notably, its metastable morph was prepared before the stable form, conforming to Ostwald's rule.
When a sample of xylitol in the metastable form is brought into a lab where the stable form had previously been made, the sample would change into the stable form after a few days in the open air. The structure of only the stable crystal was determined by X-ray diffraction in a 1969 publication. The researchers failed to obtain the metastable form from a solution in alcohol, either at room temperature or near freezing; they invariably grew only the stable form. This seems to be because once the stable form has been made in a lab, its "seeds" or nuclei can disperse in air, influencing new crystals to grow the same way.
Cephadroxil
Cefadroxil is an antibiotic. Bristol-Myers Squibb (BMS) patented the "Bouzard form" under US Patent No. 4,504,657 ('657) in 1985. The patenting took 6 years due to disputes about polymorphs. An earlier patent (US Patent No. 3,781,282) covered a different form, the "Micetich form". Attempts to replicate the Micetich form according to Example 19 in the '282 patent consistently yielded the Bouzard form, leading to challenges that the '657 patent was already inherent in the '282 patent, thus invalidated by prior art. BMS argued that the prevalence of the Bouzard form in manufacturing facilities led to unintentional seeding. Experimental tests of the seeding theory were ambiguous, but eventually the patent was granted.
Later, Zenith Laboratories marketed a cefadroxil hemihydrate. BMS sued for "gastrointestinal infringement", claiming it converted to the patented Bouzard form in the stomach. The case hinged on the interpretation of X-ray diffraction data, with BMS arguing it demonstrated the presence of the Bouzard form in patients who ingested Zenith's product. However, the court sided with Zenith.
Ranitidine
Ranitidine, a medicine for peptic ulcers sold under the name of Zantac, was developed by Allen & Hanburys (then a part of Glaxo Group Research, now GSK), and patented in 1978 (US4128658A, Example 32). Originally, its crystals were all in Form 1, but the batch prepared on April 15, 1980 exhibited a new infrared spectrogram peak at 1045 , demonstrating that a new crystal had appeared, designated Form 2. Subsequent batches produced more and more Form 2 despite using the same procedure, until Form 1 completely disappeared. The group patented Form 2 in 1985 (US4521431A ) and 1987 (US4672133A).
Though it is very difficult to crystalize Form 1 in the presence of seeds of Form 2, once Form 1 crystals are obtained, they can coexist indefinitely with Form 2 crystals when mixed together.
As the 1978 patent was nearing its 1995 expiration, many generics companies attempted to develop generics using the procedure described in 1978 patent, but they all ended up with Form 2. Some generics companies (such as Novopharm) claimed that Glaxo never produced Form 1, and thus the 1978 patent inherently anticipated Form 2, thus invalidating the 1985 and 1987 patents (since double patenting is invalid). If the argument holds, then Form 2 could be marketed as generics in 1995 at the expiration of the 1978 patent. Since an additional seven years of exclusive marketing is highly profitable, Glaxo fought back.
In order to win the first Glaxo, Inc. v. Novopharm, Ltd case, Glaxo argued successfully that Form 1 could be produced according to the 1978 patent procedure in a carefully quarantined environment, and that Novopharm had been producing Form 2 due to disappearing polymorphs. The organic chemist Jack Baldwin, acting as a witness to Glaxo, had two of his postdoctoral researchers, for three times, produce Form 1 according to the 1978 patent procedure. Consequently, the court ruled that Form 2 is covered by the 1985 patent.
Subsequent to losing the case, Novopharm attempted to bring Form 1 to market, so Glaxo sued them again in the second Glaxo, Inc. v. Novopharm, Ltd case. Glaxo argued that Novopharm could not market generics containing even trace amounts of Form 2. In particular, that means any generic Zantac containing an infrared spectrogram peak at 1045 infringes their 1985 patent. However, during the prosecution of the first case, Glaxo had already accepted that the 1985 patent covered only products containing chemicals with a specific, 29-peak infrared (IR) spectrum. This was intended to avoid double patenting—Glaxo had to emphasize the unique aspects of Form 2 to distinguish it from the invention described in the 1978 patent. Since Glaxo could not establish the presence of the 29-peak IR spectrogram in Novopharm's product, the court ruled in favor of Novopharm.
In fiction
In the 1963 novel Cat's Cradle, by Kurt Vonnegut, the narrator learns about Ice-nine, an alternative structure of water that is solid at room temperature and acts as a seed crystal upon contact with ordinary liquid water, causing that liquid water to instantly freeze and transform into more Ice-nine. Later in the book, a character frozen in Ice-nine falls into the sea. Instantly, all the water in the world's seas, rivers, and groundwater transforms into solid Ice-nine, leading to a climactic doomsday scenario.
Ice-nine has been described as a fictional parallel—a seed crystal triggering a chain reaction akin to the disappearing polymorph phenomenon.
In an indirect homage to Cat's Cradle, Ice-nine and its doomsday scenario is also mentioned in the 2009 video game 999: Nine Hours, Nine Persons, Nine Doors. A character additionally describes a rumor that glycerin was not observed to crystallize until 1920, when a batch spontaneously crystallized independently of a seed crystal. From that incident forward, all glycerin globally was observed to crystallize when cooled to under 64 degrees Fahrenheit, regardless of whether it had come into contact with a seed crystal or not.
See also
Dynamical system
Memetics
Metastability
Ostwald's Rule of Stages
Prion
Schild's Ladder
Self-replicating machine
Self-replication
Strangelet#Potential propagation
Notes
References
Polymorphism (materials science)
Fiction about chemists | Disappearing polymorph | [
"Materials_science",
"Engineering"
] | 4,164 | [
"Polymorphism (materials science)",
"Materials science"
] |
62,448,778 | https://en.wikipedia.org/wiki/H2356-309 | H2356-309 is a blazar (a type of active galactic nucleus) located behind the Sculptor Wall.
Discovery
Using the Chandra X-ray Observatory and the XMM-Newton, scientists have detected a warm-hot intergalactic medium (WHIM) between galaxies in the Sculptor Wall. Scientists observed the absorption of a background light source in the warm-hot intergalactic medium. This background source is the blazar H2356-309.
Application
Characteristics of this absorption in the Sculptor Wall by the oxygen atoms in particular are similar to the absorption of the oxygen atoms in warm-hot intergalactic medium, giving scientists more assurance they can find other sources that compare to warm-hot intergalactic medium. There are also similarities in the predicted temperature and density of the warm-hot intergalactic medium compared to the Sculptor Wall.
References
Blazars
Quasars
Sculptor (constellation) | H2356-309 | [
"Astronomy"
] | 186 | [
"Constellations",
"Sculptor (constellation)"
] |
62,449,173 | https://en.wikipedia.org/wiki/Eric%20Steig | Eric Steig is a Canadian-American scientist specializing in polar climate, glaciology, isotope geochemistry, and ice core science.
Steig is the Ben Rabinowitz Professor of Earth and Space Sciences at the University of Washington. He is also adjunct professor in the Department of Atmospheric Sciences.
Steig served as Chair of the University of Washington's Department of Earth and Space Sciences from 2020 to 2024 and Director of the Quaternary Research Center from 2008 to 2014.
He has published more than 175 peer-reviewed scientific papers on topics including ice-core analysis, polar climate variability, and ice-sheet history. He is best known for his work on climate change in Antarctica and its influence on the stability of the Antarctic ice sheet, and for research in the British Columbia Coast Range mountains. He is also known for development of novel methods in laser spectroscopy, including the analysis of the rare oxygen-17 isotope in water.
He was Senior Editor of the journal Quaternary Research from 2004 to 2008, and a member of the Board of Reviewing Editors for Science (journal) from 2013 to 2018.
Steig was one of the founding contributors to RealClimate, the first prominent blog about climate science written by scientists, which was founded "to provide responses to and context for press coverage of climate
research". He was elected a Fellow of the American Association
for the Advancement of Science in 2019, in part for this "early innovation in science communication". He has also been recognized as a National Academy of Sciences Kavli
Fellow.
In 2023, he was elected a Fellow of the American Geophysical Union "for numerous fundamental contributions in ice core, paleoclimate, and climate dynamics research". He was awarded a Guggenheim Fellowship in 2024.
References
External links
Faculty page
American glaciologists
Living people
Fellows of the American Geophysical Union
Fellows of the American Association for the Advancement of Science
University of Washington faculty
University of Washington alumni
American geochemists
Canadian geochemists
Canadian glaciologists
University of Colorado faculty
Academics of the University of Edinburgh
Hampshire College alumni
University of Pennsylvania faculty
Year of birth missing (living people) | Eric Steig | [
"Chemistry"
] | 432 | [
"Geochemists",
"Canadian geochemists",
"American geochemists"
] |
62,450,390 | https://en.wikipedia.org/wiki/Stable%20matching%20polytope | In mathematics, economics, and computer science, the stable matching polytope or stable marriage polytope is a convex polytope derived from the solutions to an instance of the stable matching problem.
Description
The stable matching polytope is the convex hull of the indicator vectors of the stable matchings of the given problem. It has a dimension for each pair of elements that can be matched, and a vertex for each stable matching. For each vertex, the Cartesian coordinates are one for pairs that are matched in the corresponding matching, and zero for pairs that are not matched.
The stable matching polytope has a polynomial number of facets. These include the conventional inequalities describing matchings without the requirement of stability (each coordinate must be between 0 and 1, and for each element to be matched the sum of coordinates for the pairs involving that element must be exactly one), together with inequalities constraining the resulting matching to be stable (for each potential matched pair elements, the sum of coordinates for matches that are at least as good for one of the two elements must be at least one). The points satisfying all of these constraints can be thought of as the fractional solutions of a linear programming relaxation of the stable matching problem.
Integrality
It is a theorem of that the polytope described by the facet constraints listed above has only the vertices described above. In particular it is an integral polytope. This can be seen as an analogue of the theorem of Garrett Birkhoff that an analogous polytope, the Birkhoff polytope describing the set of all fractional matchings between two sets, is integral.
An equivalent way of stating the same theorem is that every fractional matching can be expressed as a convex combination of integral matchings. prove this by constructing a probability distribution on integral matchings whose expected value can be set equal to any given fractional matching. To do so, they perform the following steps:
Consider for each element on one side of the stable matching problem (the doctors, say, in a problem matching doctors to hospitals) the fractional values assigned to pairings with the elements on the other side (the hospitals), and sort these values in decreasing order by that doctor's preferences.
Partition the unit interval into subintervals, of lengths equal to these fractional values, in the sorted order. Choosing a random number in the unit interval will give a random match for the selected doctor, with probability equal to the fractional weight of that match.
Symmetrically, consider for each element on the other side of the stable matching (the hospitals), sort the fractional values for pairings involving that element in increasing order by preference, and construct a partition of the unit interval whose subintervals have these fractional values in the sorted order.
It can be proven that, for each matched pair, the subintervals associated with that pair are the same in both the partition for the doctor and the partition for the hospital in that pair. Therefore, choosing a single random number in the unit interval, and using that choice to simultaneously select a hospital for each doctor and a doctor for each hospital, gives a matching. Moreover, this matching can be shown to be stable.
The resulting randomly chosen stable matching chooses any particular matched pair with probability equal to the fractional coordinate value of that pair.
Therefore, the probability distribution over stable matchings constructed in this way provides a representation of the given fractional matching as a convex combination of integral stable matchings.
Lattice of fractional matchings
The family of all stable matchings forms a distributive lattice, the lattice of stable matchings, in which the join of two matchings gives all doctors their preference among their assigned hospitals in the two matchings, and the meet gives all hospitals their preference.
The same is true of the family of all fractional stable matchings, the points of the stable matching polytope.
In the stable matching polytope, one can define one matching to dominate another if, for every doctor and hospital, the total fractional value assigned to matches for that doctor that are at least as good (for the doctor) as that hospital are at least as large in the first matching as in the second.
This defines a partial order on the fractional matchings. This partial order has a unique largest element, the integer stable matching found by a version of the Gale–Shapley algorithm in which the doctors propose matches and the hospitals respond to the proposals. It also has a unique smallest element, the integer stable matching found by a version of the Gale–Shapley algorithm in which the hospitals make the proposals.
Consistently with this partial order, one can define the meet of two fractional matchings to be a fractional matching that is as low as possible in the partial order while dominating the two matchings. For each doctor and hospital, it assigns to that potential matched pair a weight that makes the total weight of that pair and all better pairs for the same doctor equal to the larger of the corresponding totals from the two given matchings. The join is defined symmetrically.
Applications
By applying linear programming to the stable matching polytope, one can find the minimum or maximum weight stable matching. Alternative methods for the same problem include applying the closure problem to a partially ordered set derived from the lattice of stable matchings, or applying linear programming to the order polytope of this partial order.
Relation to order polytope
The property of the stable matching polytope, of defining a continuous distributive lattice is analogous to the defining property of a distributive polytope, a polytope in which coordinatewise maximization and minimization form the meet and join operations of a lattice. However, the meet and join operations for the stable matching polytope are defined in a different way than coordinatewise maximization and minimization. Instead, the order polytope of the underlying partial order of the lattice of stable matchings provides a distributive polytope associated with the set of stable matchings, but one for which it is more difficult to read off the fractional value associated with each matched pair. In fact, the stable matching polytope and the order polytope of the underlying partial order are very closely related to each other: each is an affine transformation of the other.
References
Stable matching
Polyhedral combinatorics | Stable matching polytope | [
"Mathematics"
] | 1,309 | [
"Polyhedral combinatorics",
"Combinatorics"
] |
62,450,890 | https://en.wikipedia.org/wiki/NGC%205728 | NGC 5728 is an active barred spiral galaxy located 146 million light years away in the southern constellation of Libra. It was discovered on May 7, 1787 by William Herschel. The designation comes from the New General Catalogue of J. L. E. Dreyer, published in 1888. It has an apparent visual magnitude of 13.40 and spans an angle of . The galaxy shows a red shift of 0.00935 and has a heliocentric radial velocity of 2,803 km/s. It has an estimated mass of 72 billion times the mass of the Sun and stretches around across.
The morphological classification of this galaxy is SAB(r)a?, which indicates a weakly barred spiral galaxy (SAB) with a ring-like structure (r) and possible tightly wound arms (a?). The Spitzer galactic survey lists a morphology code of (R1)SB(l,bl,nr,nb)0/a, meaning a barred spiral having a closer outer ring and an inner pseudo-ring/lens, plus a nuclear ring and bar/bar-lens. Vera Rubin described it as having a "distinct elliptical structure intermediate between a spheroid and a disk". Asymmetrical gas distribution in the galaxy suggests it has undergone a minor merger event that did not produce tidal tails.
In addition to the main bar, there is what appears to be a counter-rotating nuclear bar in the inner , which is at an angle of 60° from the main bar. There is evidence of star formation, but that has nearly ceased in the nuclear region due to the molecular gas being all but exhausted. The nuclear bar, if it exists, now consists of stars with little surrounding gas.
This is a Seyfert galaxy of type 2, indicating it has an obscured active galactic nucleus (AGN) powered by a supermassive black hole at the center. The estimated mass of this object is and it is accreting mass at the rate of . Energy released by the AGN is visible in the form of ionized cones that extend outward from the nucleus to a distance of more than , and lie across the line of sight from the Earth. X-ray and radio jets have been detected. The nucleus is being fed by spiraling filaments and dust lanes from the surrounding galaxy. The AGN itself is hidden behind a bar of dust approximately 64 pc in length. The outflow from the core is encountering the galactic ring at a distance of and is significantly enhancing star formation in that region compared to other parts of the ring.
The type Ia supernova SN 2009Y was reported in February 2009, before it reached maximum. It was magnitude 16.0 at discovery and located north and east of the center of NGC 5728.
References
External links
Libra (constellation)
Barred spiral galaxies
Seyfert galaxies
5728 | NGC 5728 | [
"Astronomy"
] | 585 | [
"Libra (constellation)",
"Constellations"
] |
62,451,797 | https://en.wikipedia.org/wiki/Meitei%20architecture | Meitei architecture, sometimes also referred to as Manipuri architecture, is the architecture produced by the Meitei speaking people, whose culture flourished in the Kangleipak kingdom and its neighbouring kingdoms from the middle of the fifteenth century BC.
The Meitei architecture is best known for its temples (Laishang, Kiyong, Thellon), found scattered in the Kangleipak (present day Manipur). Other architectural forms that are still in existence are the grand gates (Hojang), Traditional houses (Yumjao), Public houses (Sanglen), Official buildings (Loishang), etc.
Styles
Meitei-style temples and other buildings are easily distinguished by the Holy Chirong (horns) at the top of the roof. Some significant examples include Hiyangthang Lairembi Temple and Sanamahi Kiyong Temple.
There are also animal figures such as bulls and buffaloes carved on the walls.
Gallery
See also
Hiyangthang Lairembi Temple
Lainingthou Sanamahi Kiyong
Pakhangba Temple, Kangla
References
Meitei architecture
Indian architectural history
Indian architectural styles
History of Manipur
Meitei culture | Meitei architecture | [
"Engineering"
] | 245 | [
"Meitei architecture",
"Architecture"
] |
62,453,533 | https://en.wikipedia.org/wiki/East-west%20traffic | In computer networking, east-west traffic is network traffic among devices within a specific data center. The other direction of traffic flow is north-south traffic, data flowing from or to a system physically residing outside the data center.
Traffic
As a result of virtualization, private cloud, converged, and hyper-converged infrastructure adoption, east-west traffic volumes have increased.
Today many virtual functions including virtual firewalls, load balancers and other software-defined networking (SDN) perform various functions and services that previously ran on physical hardware.
As these components relay data to each other, they increase traffic on the network, which can increase latency and cause network congestion.
As disaggregated compute and storage becomes popular, east-west traffic volumes will increase.
Traditionally, many data centers today deploy their systems using a fat-tree or CLOS topology. In this network topology, servers and appliances that host applications are deployed within the racks. There is a top of the rack (ToR) switch (a leaf switch) that connects the systems within the rack as well as to other spine switches. The spine switches connect ToRs as well as provide connectivity to other spine switches through another layer of switch.
Applications communicate with other applications running on other systems for typical services, such as accessing an asset stored in another device, gathering results from a micro-service task(s) executed on other systems, or simply getting a status update from management software.
See also
Virtual private network
References
Data processing
Computer data
Electronics | East-west traffic | [
"Technology"
] | 307 | [
"Computer data",
"Data"
] |
62,453,535 | https://en.wikipedia.org/wiki/Caveasphaera | Caveasphaera is a multicellular organism found in 609-million-year-old rocks laid down during the Ediacaran period in the Guizhou Province of South China. The organism is not easily defined as an animal or non-animal. The organism is notable due to the study of related embryonic fossils (measuring about a half-millimeter in diameter) which display different stages of its development: from early single-cell stages to later multicellular stages. Such fossil studies present the earliest evidence of an essential step in animal evolution – the ability to develop distinct tissue layers and organs. According to researchers, fossil studies of Caveasphaera have suggested that animal-like embryonic development arose much earlier than the oldest clearly defined animal fossils and may be consistent with studies suggesting that animal evolution may have begun about 750 million years ago. Nonetheless, Caveasphaera fossils may look similar to starfish and coral embryos. Still, researchers have concluded, "Parental investment in the embryonic development of Caveasphaera and co-occurring Tianzhushania and Spiralicellula, as well as delayed onset of later development, may reflect an adaptation to the heterogeneous nature of the early Ediacaran nearshore marine environments in which early animals evolved."
References
Enigmatic eukaryote taxa
Tree of life (biology) | Caveasphaera | [
"Biology"
] | 273 | [
"Tree of life (biology)"
] |
62,454,450 | https://en.wikipedia.org/wiki/HD%20111395 | HD 111395 is a single, variable star in the northern constellation of Coma Berenices. It has the variable star designation LW Com, short for LW Comae Berenices; HD 111395 is the Henry Draper Catalogue designation. The star has a yellow hue and is just bright enough to be barely visible to the naked eye with an apparent visual magnitude that fluctuates around 6.29. Based upon parallax measurements, it is located at a distance of 55.8 light years from the Sun. The star is drifting closer with a radial velocity of −8.9 km/s. It is a member of the Eta Chamaeleontis stellar kinematic group.
This object is a G-type main-sequence star with a stellar classification of G7V. It is a BY Draconis variable that varies in brightness by about 0.10 magnitude over a period of 15.8 days, which is interpreted as the rotation period of the star. (Messina et al. (2003) suspect the actual rotation period may be half that: 7.9 days.) It has an active chromosphere and is a source for X-ray emission.
The star is around a billion years old with a projected rotational velocity of 3.8 km/s. It has slightly above solar metallicity − the term astronomers use for the relative abundance of elements other than hydrogen and helium. The mass of the star is 8% greater than the Sun, but it has 93% of the Sun's radius. It is radiating 80% of the luminosity of the Sun from its photosphere at an effective temperature of 5649 K. An infrared excess indicates a cold debris disk is orbiting the star at a distance of with a mean temperature of 60 K. The disk has an estimated mass of .
References
G-type main-sequence stars
BY Draconis variables
Circumstellar disks
Coma Berenices
4864
Durchmusterung objects
Gliese and GJ objects
111395
62523
Comae Berenices, LW | HD 111395 | [
"Astronomy"
] | 425 | [
"Coma Berenices",
"Constellations"
] |
62,455,026 | https://en.wikipedia.org/wiki/Canadian%20Centre%20for%20Alternatives%20to%20Animal%20Methods | The Canadian Centre for Alternatives to Animal Methods (CCAAM) was a research centre founded in 2017 and based at the University of Windsor, in Canada. Its goal was "to develop, validate, and promote laboratory methods and techniques that don't use animal test subjects". It was the first centre in Canada dedicated to non-animal testing and the promotion of human-relevant alternatives. The CCAAM ceased operations on May 31, 2024 due to budget cuts at the University of Windsor.
Mission and projects
The CCAAM's mission was based on three pillars:
scientific research relying exclusively on human-based biomaterials and human biology-based methodologies, including human cells, stem cells, tissues from cadavers, biopsies, and explanted organs from surgeries;
academic training for scientists, ethicists, regulators, and policy makers, including development of a one-year masters programme;
regulatory initiatives for changing chemical safety methods in Canada, with academic, industry, government, and public partnerships.
One of its main focuses of research is diabetes, using “human stem cells to create diabetes in a dish”. The CCAAM is opposed to animal testing based on ethical and scientific reasons. The director, biochemist Dr. Charu Chandrasekera who specializes in heart disease and diabetes, states that “Ninety-five per cent of drugs tested to be safe and effective in animal models fail in human clinical trials”.
Funding
In 2018, it received a $1 million donation from the Eric S. Margolis Family Foundation, considered “the largest research donation in University of Windsor history”, part of which will be used to create a research and training facility.
See also
Alternatives to animal testing
Center for Alternatives to Animal Testing
Pain and suffering in laboratory animals
Animal testing regulations
References
Animal testing techniques
Laboratory techniques
Human subject research
University of Windsor | Canadian Centre for Alternatives to Animal Methods | [
"Chemistry"
] | 380 | [
"Animal testing",
"Animal testing techniques",
"nan"
] |
62,455,443 | https://en.wikipedia.org/wiki/Roth%27s%20theorem%20on%20arithmetic%20progressions | Roth's theorem on arithmetic progressions is a result in additive combinatorics concerning the existence of arithmetic progressions in subsets of the natural numbers. It was first proven by Klaus Roth in 1953. Roth's theorem is a special case of Szemerédi's theorem for the case .
Statement
A subset A of the natural numbers is said to have positive upper density if
.
Roth's theorem on arithmetic progressions (infinite version): A subset of the natural numbers with positive upper density contains a arithmetic progression.
An alternate, more qualitative, formulation of the theorem is concerned with the maximum size of a Salem–Spencer set which is a subset of . Let be the size of the largest subset of which contains no arithmetic progression.
Roth's theorem on arithmetic progressions (finitary version): .
Improving upper and lower bounds on is still an open research problem.
History
The first result in this direction was Van der Waerden's theorem in 1927, which states that for sufficiently large N, coloring the integers with colors will result in a term arithmetic progression.
Later on in 1936 Erdős and Turán conjectured a much stronger result that any subset of the integers with positive density contains arbitrarily long arithmetic progressions. In 1942, Raphaël Salem and Donald C. Spencer provided a construction of a 3-AP-free set (i.e. a set with no arithmetic progressions) of size , disproving an additional conjecture of Erdős and Turán that for some .
In 1953, Roth partially resolved the initial conjecture by proving they must contain an arithmetic progression of length 3 using Fourier analytic methods. Eventually, in 1975, Szemerédi proved Szemerédi's theorem using combinatorial techniques, resolving the original conjecture in full.
Proof techniques
The original proof given by Roth used Fourier analytic methods. Later on another proof was given using Szemerédi's regularity lemma.
Proof sketch via Fourier analysis
In 1953, Roth used Fourier analysis to prove an upper bound of . Below is a sketch of this proof.
Define the Fourier transform of a function to be the function satisfying
,
where .
Let be a 3-AP-free subset of . The proof proceeds in 3 steps.
Show that a admits a large Fourier coefficient.
Deduce that there exists a sub-progression of such that has a density increment when restricted to this subprogression.
Iterate Step 2 to obtain an upper bound on .
Step 1
For functions, define
Counting Lemma Let satisfy . Define . Then .
The counting lemma tells us that if the Fourier Transforms of and are "close", then the number of arithmetic progressions between the two should also be "close." Let be the density of . Define the functions (i.e the indicator function of ), and . Step 1 can then be deduced by applying the Counting Lemma to and , which tells us that there exists some such that
.
Step 2
Given the from step 1, we first show that it's possible to split up into relatively large subprogressions such that the character is roughly constant on each subprogression.
Lemma 1: Let . Assume that for a universal constant . Then it is possible to partition into arithmetic progressions with length such that for all .
Next, we apply Lemma 1 to obtain a partition into subprogressions. We then use the fact that produced a large coefficient in step 1 to show that one of these subprogressions must have a density increment:
Lemma 2: Let be a 3-AP-free subset of , with and . Then, there exists a sub progression such that and .
Step 3
We now iterate step 2. Let be the density of after the th iteration. We have that and First, see that doubles (i.e. reach such that ) after at most steps. We double again (i.e reach ) after at most steps. Since , this process must terminate after at most steps.
Let be the size of our current progression after iterations. By Lemma 2, we can always continue the process whenever and thus when the process terminates we have that Also, note that when we pass to a subprogression, the size of our set decreases by a cube root. Therefore
Therefore so as desired.
Unfortunately, this technique does not generalize directly to larger arithmetic progressions to prove Szemerédi's theorem. An extension of this proof eluded mathematicians for decades until 1998, when Timothy Gowers developed the field of higher-order Fourier analysis specifically to generalize the above proof to prove Szemerédi's theorem.
Proof sketch via graph regularity
Below is an outline of a proof using the Szemerédi regularity lemma.
Let be a graph and . We call an -regular pair if for all with , one has .
A partition of is an -regular partition if
.
Then the Szemerédi regularity lemma says that for every , there exists a constant such that every graph has an -regular partition into at most parts.
We can also prove that triangles between -regular sets of vertices must come along with many other triangles. This is known as the triangle counting lemma.
Triangle Counting Lemma: Let be a graph and be subsets of the vertices of such that are all -regular pairs for some . Let denote the edge densities respectively. If , then the number of triples such that form a triangle in is at least
.
Using the triangle counting lemma and the Szemerédi regularity lemma, we can prove the triangle removal lemma, a special case of the graph removal lemma.
Triangle Removal Lemma: For all , there exists such that any graph on vertices with less than or equal to triangles can be made triangle-free by removing at most edges.
This has an interesting corollary pertaining to graphs on vertices where every edge of lies in a unique triangle. In specific, all of these graphs must have edges.
Take a set with no arithmetic progressions. Now, construct a tripartite graph whose parts are all copies of . Connect a vertex to a vertex if . Similarly, connect with if . Finally, connect with if .
This construction is set up so that if form a triangle, then we get elements that all belong to . These numbers form an arithmetic progression in the listed order. The assumption on then tells us this progression must be trivial: the elements listed above are all equal. But this condition is equivalent to the assertion that is an arithmetic progression in . Consequently, every edge of lies in exactly one triangle. The desired conclusion follows.
Extensions and generalizations
Szemerédi's theorem resolved the original conjecture and generalized Roth's theorem to arithmetic progressions of arbitrary length. Since then it has been extended in multiple fashions to create new and interesting results.
Furstenberg and Katznelson used ergodic theory to prove a multidimensional version and Leibman and Bergelson extended it to polynomial progressions as well. Most recently, Green and Tao proved the Green–Tao theorem which says that the prime numbers contain arbitrarily long arithmetic progressions. Since the prime numbers are a subset of density 0, they introduced a "relative" Szemerédi theorem which applies to subsets with density 0 that satisfy certain pseudorandomness conditions. Later on Conlon, Fox, and Zhao strengthened this theorem by weakening the necessary pseudorandomness condition. In 2020, Bloom and Sisask proved that any set such that diverges must contain arithmetic progressions of length 3; this is the first non-trivial case of another conjecture of Erdős postulating that any such set must in fact contain arbitrarily long arithmetic progressions.
Improving bounds
There has also been work done on improving the bound in Roth's theorem. The bound from the original proof of Roth's theorem showed that
for some constant . Over the years this bound has been continually lowered by Szemerédi, Heath-Brown, Bourgain, and Sanders. The current (July 2020) best bound is due to Bloom and Sisask who have showed the existence of an absolute constant c>0 such that
In February 2023 a preprint (later published) by Kelley and Meka gave a new bound of:
.
Four days later, Bloom and Sisask published a preprint giving an exposition of the result (later published), simplifying the argument and yielding some additional applications. Several months later, Bloom and Sisask obtained a further improvement to , and stated (without proof) that their techniques can be used to show .
There has also been work done on the other end, constructing the largest set with no arithmetic progressions. The best construction has barely been improved since 1946 when Behrend improved on the initial construction by Salem and Spencer and proved
.
Due to no improvements in over 70 years, it is conjectured that Behrend's set is asymptotically very close in size to the largest possible set with no progressions. If correct, the Kelley-Meka bound will prove this conjecture.
Roth's theorem in finite fields
As a variation, we can consider the analogous problem over finite fields. Consider the finite field , and let be the size of the largest subset of which contains no arithmetic progression. This problem is actually equivalent to the cap set problem, which asks for the largest subset of such that no 3 points lie on a line. The cap set problem can be seen as a generalization of the card game Set.
In 1982, Brown and Buhler were the first to show that In 1995, Roy Mesuhlam used a similar technique to the Fourier-analytic proof of Roth's theorem to show that This bound was improved to in 2012 by Bateman and Katz.
In 2016, Ernie Croot, Vsevolod Lev, Péter Pál Pach, Jordan Ellenberg and Dion Gijswijt developed a new technique based on the polynomial method to prove that .
The best known lower bound is , discovered in December 2023 by Google DeepMind researchers using a large language model (LLM).
Roth's theorem with popular differences
Another generalization of Roth's theorem shows that for positive density subsets, there not only exists a arithmetic progression, but that there exist many 3-APs all with the same common difference.
Roth's theorem with popular differences: For all , there exists some such that for every and with there exists some such that
If is chosen randomly from then we would expect there to be progressions for each value of . The popular differences theorem thus states that for each with positive density, there is some such that the number of 3-APs with common difference is close to what we would expect.
This theorem was first proven by Green in 2005, who gave a bound of where is the tower function. In 2019, Fox and Pham recently improved the bound to
A corresponding statement is also true in for both 3-APs and 4-APs. However, the claim has been shown to be false for 5-APs.
References
External links
Edmonds, Chelsea; Koutsoukou-Argyraki, Angeliki; Paulson, Lawrence C. Roth's Theorem on Arithmetic Progressions (Formal proof development in Isabelle/HOL, Archive of Formal Proofs)
Theorems in number theory | Roth's theorem on arithmetic progressions | [
"Mathematics"
] | 2,316 | [
"Mathematical theorems",
"Mathematical problems",
"Number theory",
"Theorems in number theory"
] |
62,456,017 | https://en.wikipedia.org/wiki/Heyde%20theorem | In the mathematical theory of probability, the Heyde theorem is the characterization theorem concerning the normal distribution (the Gaussian distribution) by the symmetry of one linear form given another. This theorem was proved by C. C. Heyde.
Formulation
Let be independent random variables. Let be nonzero constants such that for all . If the conditional distribution of the linear form given is symmetric then all random variables have normal distributions (Gaussian distributions).
References
C. C. Heyde, “Characterization of the normal law by the symmetry of a certain conditional distribution,” Sankhya, Ser. A,32, No. 1, 115–118 (1970).
A. M. Kagan, Yu. V. Linnik, and C. R. Rao, Characterization Problems in Mathematical Statistics, Wiley, New York (1973).
Probability theorems | Heyde theorem | [
"Mathematics"
] | 176 | [
"Theorems in probability theory",
"Mathematical theorems",
"Mathematical problems"
] |
62,456,128 | https://en.wikipedia.org/wiki/Junctional%20adhesion%20molecule | A junctional adhesion molecule (JAM) is a protein that is a member of the immunoglobulin superfamily, and is expressed in a variety of different tissues, such as leukocytes, platelets, and epithelial and endothelial cells. They have been shown to regulate signal complex assembly on both their cytoplasmic and extracellular domains through interaction with scaffolding that contains a PDZ domain and adjacent cell's receptors, respectively. JAMs adhere to adjacent cells through interactions with integrins LFA-1 and Mac-1, which are contained in leukocyte β2 and α4β1, which is contained in β1. JAMs have many influences on leukocyte-endothelial cell interactions, which are primarily moderated by the integrins discussed above. They interact in their cytoplasmic domain with scaffold proteins that contain a PDZ domain, which are common protein interaction modules that target short amino acid sequences at the C-terminus of proteins, to form tight junctions in both epithelial and endothelial cells as polarity is gained in the cell.
Structure
JAMs are usually around 40 kDa in size. Based on crystallographic studies conducted with recombinant extracellular mouse JAMs (rsJAM) and human JAMs (hJAM), it has been shown that JAM consists of immunoglobulin-like V-set domain followed by a second immunoglobulin domain that are linked together by a short linker sequence. The linker makes extensive hydrogen bonds to both domains, and the side chain of one of the main linker residues, Leu128, is commonly embedded in a hydrophobic cleft between each immunoglobulin-like domain. Two JAM molecules contain N-terminal domains that react in a highly complementary fashion due to prolific ionic and hydrophobic interactions. These two molecules form U-shaped dimers and salt bridges are then formed by a R(V,I,L)E motif. This motif has been proven to be important in dimer formation and is common among different types of JAMs. It commonly consists of Arg58-Val59-Glu60 located on the N-terminus and can dissociate into monomers based on the conditions of the solution it is exposed to. This motif has been shown to be present in many common variants of JAMs, including rsJAM, hJAM, JAM-1, JAM-2, and JAM-3.
Types
Three major JAM molecules interact with various molecules and receptors within the body:
JAM-1
JAM-1 was the first of the junctional adhesion molecules to be discovered, and is located in the tight junctions of both epithelial and endothelial cells. JAM-1interacts with cells in a homophilic manner in order to preserve the structure of the junction while moderating its permeability. It can also interact with receptors as a heterophilic structure by acting as a ligand for LFA-1 and facilitating leukocyte transmigration. JAM-1 also plays a significant role in many different cellular functions, including being both a reovirus receptor and a platelet receptor.
JAM-2
Like JAM-1, JAM-2 also is a member of the immunoglobulin superfamily. JAM-2 localization is moderated by serine phosphorylation at tight junctions as the molecule adheres to other tight junction proteins like PAR-3 and ZO-1. JAM-2 has been shown to interact with these proteins, primarily through the PDZ1 domain, and also through the PDZ3 domain. JAM-2 has also shown to act as a ligand for many immune cells, and plays a role in lymphocyte attraction to specific organs.
JAM-3
JAM-3 functions similarly to JAM-2 as it is localized around the tight junctions of epithelial and endothelial cells, but has been shown to be unable to adhere to leukocytes in the manner that other JAMs can. Mutations of JAM-3 introns have been shown to lead to brain hemorrhages and development of cataracts. Like JAM-2, JAM-3 has been shown associate with tight junction proteins like PAR-3 and ZO-1. JAM-3 has also been shown to interact with PARD3 (partitioning defective 3 homolog).
Function
JAMs serve many different functions within the cell:
Cell motility
JAMs play a critical role in the regulation of cell movement in multiple different cell types, such as epithelial, endothelial, leukocyte, and germ cells. JAM-1 regulates motility in epithelial cells by moderating expression of β1 integrin protein downstream of Rap1. JAM-1 has been shown to be able to cause cell adhesion, spreading and movement along β1 ligands, like collagen IV and fibronectin. JAM-1 also acts to moderate migration of vitronectin in endothelial cells. Vitronectin is a ligand for integrins αvβ3 and αvβ5, which exhibit selective cooperativity with bFGF and VEGF in the activation of the MAPK pathway. JAM-1 and JAM-3 allow leukocytes to migrate into connective tissue by freeing polymorphonuclear leukocytes from entrapment in endothelial cells and basement membranes. In the absence of JAM-1, these leukocytes cannot moderate β1 integrin endocytosis, and cannot be effectively expressed on the surface of the cell (which is essential for motility).
Cell polarity
JAM-1 and JAM-3 have significant roles in regulating cell polarity through their interactions with cell polarity proteins. JAM-1, JAM-2, and JAM-3 all interact with PAR-3 to influence cell polarity. PAR-3 is a significant factor in a cell's polarity-regulating complex, and regulates polarity in different cell types in many different organisms. All components of the PAR complex are required for tight junction formation between cells, but premature adherens junctions can form without PAR complex components being present. However, these junctions cannot efficiently develop into mature epithelial cell junctions. JAM-3 has also shown to affect cell polarity in spermatids by regulating the localization of cytosolic polarity.
Cell Proliferation
In order to preserve homeostasis of adult tissue, aged cells must be replaced with new cells at varying frequency, depending on the organ. Some organs that require high rates of cellular turnover are the small intestine and the colon. JAM-1 has been shown to regulate the proliferation of cells in the colon. In JAM-1 deficient mice, it has been found that the amount of proliferating cells in the colon greatly increased due to the increased proliferation of TA cells. JAM-1 acts to suppress cell proliferation, which is performed by restricting Akt activity. Recent studies have also pointed to JAM-1 preserving structural integrity of tissues more so than regulating cell number.
Role in physiological processes
JAMs play a significant role in many diverse physiological processes within the human body, including:
Tight junction formation
Tight junctions serve to provide most of the function for the barrier that is present on epithelial cell surfaces. Tight junctions feature the localization of both JAM-1 and JAM-3, and JAM-3 is localized exclusively at tight junctions. The role of JAM-1 in tight junction biology is to function through mediation partly due to the localization of the Par-αPKC complex at adherens junctions during junction creation. Once the tight junction is formed, many JAM-1 proteins are present, many of which are now phosphorylated at Ser285. JAM-1 also regulates the activity of many different claudins within different epithelial cells.
Angiogenesis
Angiogenesis is the generation of blood vessels from old blood vessels. Studies have shown that proteins found in tight junctions serve as intermediaries that moderate angiogenic signaling pathways. JAM-1 induces proliferation of endothelial cells, which begins the process of angiogenesis. An analysis of JAM-1 showed a correlation between JAM-1 activity and FGF2-induced angiogenesis in both cancerous proliferation or vascular repair.
Male fertility
JAM-3 has been shown to be a primary regulator of the development of spermatids as well as the rest of the male reproductive system. Within the Sertoli cells of the male reproductive system, JAM-3 interacts with JAM-2 to influence the polarity of both round and elongated spermatids. JAM-1 and JAM-2 are also present in and contribute to the polarity of the blood-testis barrier. Studies have also shown that inactivation of JAM-3 has been shown to significantly impede fertility by blocking male germ cell development and proliferation.
References
Proteins
Immunoglobulin superfamily | Junctional adhesion molecule | [
"Chemistry"
] | 1,858 | [
"Biomolecules by chemical classification",
"Proteins",
"Molecular biology"
] |
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